Technical paper abstracts Eguipment List , Software List Annual Report

BACK 1 2 3 4 5 6 7 8 9 10 NEXT NO. Title Presented at & Date Author Project Team / Research Division Abstract 12095 Microbial and chemical characterizations of oil field water through the artificial souring experiment Journal of Chemical Engineering of Japan 43(9),792-797 (2010) 2010/9/20 Takuya Handa · LIM Choon Ping · Kazuhiko Miyanaga · Yasunori Tanj (Tokyo Institute of Technology), Yasuyoshi Tomoe (JOGMEC) Petroleum Engineering Research Division The water samples collected from two non water-flooded oil fields contained a variety of organic acids, sulfate-reducing bacteria (SRB) and little sulfate. Acetate and propionate were the major component of organic acids. Through the 6 weeks of artificial souring experiment, maximum 3 mM of sulfide was produced when oil field water was mixed with seawater at 25 ℃. Propionate was completely consumed in soured conditions. This indicated the propionate-consuming SRB occurred souring in this experiment. Significant cell growth was confirmed at 25 ℃ with no relation to souring. The dominant SRB species were shifted from Desulfomicrobium thermophilum to Desulfobacter vibrioformis and uncultured Desulfobacter. 12094 Increased bioclogging and corrosion risk by sulfate addition during iodine recovery at a natural gas production plant Applied Microbiology and Biotechnology 89(3),825-834(2011) 2010/10/5 LIM Choon Ping · Zhao Dan · Kazuhiko Miyanaga · Yasunori Tanj (Tokyo Institute of Technology), Tomoko Watanabe · Yasuyoshi Tomoe (JOGMEC) Petroleum Engineering Research Division Iodine recovery at a natural gas production plant in Japan involved the addition of sulfuric acid for pH adjustment, resulting in an additional ca. 200 mg/L of sulfate in the waste brine after iodine recovery. Bioclogging occurred at the waste brine injection well, causing a decrease in well injectivity. To examine the factors that contribute to bioclogging, an on-site experiment was conducted by amending 10 liters of brine with different conditions 12090 X-ray CT-based hydrogeological core analysis with CFR-PEEK core holder Japan Geoscience Union Meeting 2011 2011/5/25 Noriaki Watanabe · Noriyoshi Tsuchiya (Tohoku University), Yutaka Ohsaki, Tetsuya Tamagawa (JAPEX), Yoshihiro Tsuchiya · Hiroshi Okabe (JOGMEC), Hisao Ito (JAMSTEC) EOR Research Division Clarifying hydraulic properties in the Earth's crust is required to understand crustal fluid migration, heat and material transport by the fluid, and accompanying water-rock interactions. For this purpose, we have studied a X-ray CT-based numerical method to analyze fracture flows within core samples at in-situ stress conditions. However, a recent study revealed that commercially available core holders could not be used, because noise in CT value was not negligible due to relatively high X-ray attenuation. In this paper, we show a new core holder, and some numerical results of fracture flow analyses for a granite sample under confining pressure. We have developed a core holder whose main body is made of a carbon fiber-reinforced PEEK (CFR PEEK), because of the low density of 1.44 g/cc and the high tensile strength of 236 MPa. The main boy of the current core holder was designed for 2-inch core samples, and had the wall thickness of 12 mm. A pressure test demonstrated the core holder could be used at up to 30 MPa. A medical X-ray CT scan for a granite sample having a saw-cut fracture demonstrated the detection limit of fracture aperture was smaller than 30 mm even with the core holder. Based on a medical X-ray CT scan at 3-10 MPa with the core holder, it was possible to analyze single-phase flow within a granite sample having a tension fracture. The results demonstrated that fracture aperture and resulting permeability distributions within the sample could be measured, and that hydraulic properties of the sample could be evaluated using the permeability distribution, by using the X-ray CT-based numerical analysis, without any experiments. 12089 Heat Transfer Analysis of Re-Gasification of Packed Bed of Hydrates 7th International Conference on Gas Hydrates (ICGH7 · 2011) 2011/7/20 Susumu Tanaka (Hiroshima University), Yousuke Nakai (Daihatsu Motor Co., Ltd.), Kiyoshi Shimada · Osamu Takano · Go Oishi (Akishima Laboratories (Mitsui Zosen) Inc.) Development and Production Division New storage and transportation system of natural gas using the gas hydrate has been researched and developed. At the present work, the new re-gasification system, in which warm water penetrates through a bed of gas hydrate pellets for the recovery of gas from stored hydrate, is investigated to achieve more compact and more efficient re-gasification system. A testing was executed by means of a bench plant, in order to grasp the influence of flow rate of water on the heat transfer of the bed of hydrate pellets with dissociating phenomena. In addition, the dissociation characteristics were investigated numerically. This paper presents outline of the bench plant re-gasification test of methane hydrate pellets as preliminary study, some experimental data and numerical data at middle pressure of 0.5MPa and high pressure of 5.0MPa. 12088 Mechanical interpretation of fault distribution within and around the methane hydrate concentrated zone, eastern Nankai Trough, Japan ICGH2011 (7th International Conference on Gas Hydrates) 2011/7/18-19 Machiko Tamaki · Satoshi Noguchi · Mineko Furukawa (JOGMEC) Methane Hydrate Research & Development Division Mechanism of structural development within and around the methane hydrate concentrated zone, Alpha, in the eastern Nankai Trough is described based on 3-D seismic survey. A surface structure delineates the normal faults well-developed at the termination of the major active thrust fault, Kodaiba fault. In order to discuss the relationship between the normal faults and Kodaiba fault, the static stress changes caused by the movement of the Kodaiba fault are estimated numerically using dislocation modelling. The results demonstrate that the normal faults can be secondary faults as a result of dip-slip movement of the Kodaiba fault. However, structural analysis using 3-D seismic data implies plunging conical drag fold, suggesting lateral displacement of the Kodaiba fault. The coulomb failure is not hypothesized to be prompt in the study area when the Kodaiba fault is considered as a right lateral strike-slip fault. The results of dislocation modeling assuming lateral motion of fault exhibit the compressional fields in the study area. In a fold produced under layer parallel compression, extensional strain is distributed at the outer arc of the hinge. Then, the normal faults are possibly formed by extensional strain during or after the folding. This is also supported from the fact that the normal faults are close to parallel to the fold axis. Structural mechanism presented by this study suggests that Alpha is distributed at a unique structure characterized by the structural high and normal faulting associated with a gentle folding. 12087 Experimental Study on The Possible Factors that Affect The Saturation of Gas Hydrate in Natural Sediments 7th International Conference on Gas Hydrates (ICGH7 · 2011) * Poster session 2011/7/18-19 Toshiyasu Ukita · Satoshi Noguchi · Tadaaki Shimada (JOGMEC), Hailong Lu · Igor Moudrakovski · John Ripmeester · Chris Ratcliffe (National Research Council Canada) Methane Hydrate Research & Development Division Natural gas hydrate exists in sediment, a complex system with various constituents, and its saturation is subject to the influence of sediment. Through a series of experimental investigations, particle size is identified as the most important factor that controls the saturation of gas hydrate in sediment. Studies also revealed that sorting of sediment and mineral composition also play certain roles in affecting hydrate saturation in sediments. The investigation about the proton relaxations of water in sediment found that the sediment control on hydrate saturation is realized through its influence in water states in sediment, some water in sediments not available for hydrate formation. 12080 Joint AVO inversion for time-lapse elastic reservoir properties: Hangingstone heavy oilfield, Alberta SEG Summer Research Workshop 2011 2011/6/27 Ayato Kato (JOGMEC), Robert R. Stewart (University of Houston) Geology and Geophysics Division We developed a time-lapse AVO inversion method, based on Bayesian method, in which all available seismic data can be used to obtain elastic properties (VP, VS, and ρ) and the changes between baseline and repeat surveys. The inverted elastic properties and the changes are consistent with the seismic data and prior information. Furthermore, the method is applicable to incomplete time-lapse multicomponent data sets. Tests on synthetic data show promising results. After mis-alignment correction, the method is applied to the Hangingstone oilfield. From the inversion result with rock physics model, distribution of heated temperature caused by steam injection is successfully obtained. 12068 Research on the next generation dynamic positioning system of offshore platform in Japan The IFAC Conference on Control Applications in Marine Systems - CAMS 2010 2010/9/15-17 Kunio Yamamoto(The University of Kitakyushu), Katsuya Maeda, Takayuki Asanuma(JOGMEC) Petroleum Engineering Research Division This paper describes dynamic positioning system developed for 20 years through research and development by Japan Oil, Gas and Metals National Corporation. It summaries a basic concept of design, simulator, tank test, and real applications. Also, the next generation system of Japan and its basic research is mentioned in the paper. 12009 Possible migration front of gas-related fluid inferred from 3D seismic in the eastern Nankai Trough Journal of the Japanese Association for Petroleum Technology Vol. 76, No. 1(Jan., 2011) 2011/1 Hirotoku Otsuka(AORI, The University of Tokyo), Sumito Morita, Manabu Tanahashi(National Institute of Advanced Industrial Science and Technology), Sadao Nagakubo(JOGMEC), Juichiro Ashi(AORI, The University of Tokyo) Methane Hydrate Research Project Team High resolution 3D seismic survey “Tokai-oki to Kumano-nada” was conducted for methane hydrate exploration in the eastern Nankai Trough by METI in 2002. Our study focuses on zigzag-shaped specific reflectors on BSR margins on the 3D data. We call the reflectors “Foldback Reflectors (FBRs)” in this study. From the edge of BSR, the 1st FBR generally extends down to lower formation below the BSR crossing sedimentary horizons. The following FBRs extend down from the edge of the upper FBR forming accordion-like shape. The 1st FBR indicates normal polarity, and the following FBRs change their polarities alternately. FBRs are mostly developed in the well-stratified formation but not in the area of frequent fractures and the area of major lateral lithological change. Dip direction of each FBR is probably controlled by that of crossing formation. FBR generally corresponds to lateral seismic facies boundary and the acoustic velocity model between BSR distribution area and outside of the BSR area. The formation beneath the BSR shows dimmed facies characterized by relatively low amplitude and lack of high frequency components with relatively low velocity in contrast to outside of the BSR area with normal facies. The lowest FBR does not cross major unconformities, which often exhibit negative polarity suggesting fluid bearing strata. In addition, high amplitude layers are sometimes recognized at foldbacks convex to the outside of the BSR area. These high amplitude layers probably having higher permeability are interpreted as conduits of gas-related fluid from the BSR area to the outside of the BSR area. The whole shapes of FBRs are possibly related to layer-parallel migration in the strata which have wide range of permeability. From these observations, FBR can be regarded as an important proxy indicating migration front of gas-related fluid. We appreciate MH21, METI and JOGMEC for permission to use the data. 12058 Possible migration front of gas-related fluid inferred from 3D seismic in the eastern Nankai Trough (American Geophysical Union) 2010 AGU Fall Meeting 2010/12/13 Hirotoku Otsuka(AORI, The University of Tokyo) , Sumito Morita, Manabu Tanahashi(National Institute of Advanced Industrial Science and Technology), Juichiro Ashi(AORI, The University of Tokyo), Sadao Nagakubo(JOGMEC) Methane Hydrate Research Project Team High resolution 3D seismic survey, “Tokai-oki to Kumano-nada”, was conducted for methane hydrate exploration in the eastern Nankai Trough by METI in 2002. Our study focuses on a series of accordion-shaped reflectors with horizontal axis of fold back. They are connected to the edge of BSRs and alternate their polarities at every fold back hinge. We call the reflectors “Foldback Reflectors (FBRs)” in this study. Sedimentary horizons are successive across these series of reflectors with no fault displacement as a general rule. FBR generally corresponds to lateral seismic facies boundary between BSR distribution area and outside of the BSR area. The formation beneath the BSR shows dimmed facies characterized by relatively low amplitude and lack of high frequency components in contrast to outside of the BSR area with normal facies. Seismic velocity analysis suggests that FBRs correspond to velocity boundaries, where the dimmed faceis below the BSR coinsides with relatively low velocity. The polarities of FBRs are also consistent with such velocity changes. Such dimmed facies with low velocity and low amplitude anomaly suggests effects of gas components in the pore water. In this area, FBRs are mostly developed in the well-stratified formation but not in the area of frequent fractures and the area of major lateral lithological change. The observed FBRs are clustered in northern slope of the uplifted outer ridge, whereas few FBRs are developed in the southern slope of the outer ridge with frequent compressive and strike-slip deformations related to major fault systems including the Kodaiba faults and the Tokai faults. The estimated strike directions of each FBRs are probably controlled by the dip direction of crossing formation. Another important character of FBRs is that it never crosses major unconformities into lower strata. In addition, high amplitude layers are sometimes recognized at hinges of foldbacks convex to the outside of the BSR area. These high amplitude layers probably having higher permeability are interpreted as conduits of gas-related fluid from the BSR distribution side to the outside of the BSR area. From these facts, FBR can be regarded as an important proxy indicating fluid distribution and possible migration front of gas-related fluid. This study used data provided by JOGMEC and MH21 Research Consortium for Methane Hydrate Resources in Japan. 12051 3-D internal architecture of methane hydrate bearing turbidite channels in the eastern Nankai Trough, Japan International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Satoshi Noguchi, Kunio Akihisa, Toshiko Furukawa, Nobutaka Oikawa, Toshiaki Kobayashi, Tadaaki Shimada, Tatsuo Saeki (JOGMEC), Takao Inamori(JGI, Inc.) , Takayuki Sugano(Schlumberger) Methane Hydrate Research Project Team The reservoir architecture of methane hydrate (MH) bearing turbidite channels in the eastern Nankai Trough, offshore Japan is discussed using a combination of 3-D seismic and well log data. The MH bearing turbidite channels consist of complex patterns of strong seismic reflectors, which exhibit a 3-D internal architecture of the channel complex extending to northeast–southwest direction. According to a seismic sequence stratigraphic analysis, the channel complex can be roughly classified into three depositional sequences. Each depositional sequence results in the different depositional system, which primarily controls the reservoir architecture of the turbidite channels. In the southwestern part of the channel complex around β2 well, the thickness of the turbidite channels is much greater than that of the northeastern part of the channel complex around β1 well. However, the depositional sequence of the northeastern part indicates a sand-dominated turbidite layers ensuring that the reservoir potential is high despite the relatively smaller thickness of the turbidite channels. For constructing a geological frame model, we examined further details of reservoir characteristics of the geological frame of the channels around β1 well. The bottom frame of several channels is oriented along north-to-south and north-northeast-to-south-southwest directions, which coincide with the distributary patterns of the higher amplitude values in amplitude map. The several magnitudes of these amplitude patterns within the turbidite channels reveal complex stacking patterns of several orders of the flow units. An anomalously high interval velocity between BSR (bottom simulating reflector) and the top of the MH bearing sediments is identified in the northeastern part of the channels. The turbidite sediments in the northeastern side of channels are derived from the north-northeast direction, which is different from the sediments supply systems of the rest of the channels. The different sediments supply system of northeastern side of channels is related to the abundance of coarse sediments, which may lead to the different reservoir architecture of the turbidite channels. 12050 Reservoir response observation by geophysical logging and monitoring program International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Satoshi Noguchi, Tetsuya Fujii, Tokujiro Takayama(JOGMEC) , Kasumi Fujii(Schlumberger) Methane Hydrate Research Project Team Physical property changes of methane hydrates bearing formations throughout a production are quantitatively evaluated using a time-lapse analysis (before/after the production test) of a cased-hole log data. Three kinds of the cased-hole measurements enable us to interpret the dissociation behavior of the methane hydrates throughout the production. Reservoir Saturation Tool (RST) data show that RST sigma (Cl) after the production test drastically increases an entire part of a perforated interval (1093-1105 m). This suggests that high concentration of KC brine (5 %KCl) and/or formation water was replaced due to the dissociation of hydrates in the formation. APS porosity obtained by Accelerator Porosity Sonde (APS) also increases up to 20 % after the production test indicating that the hydrates are selectively dissociated. Time-lapse analysis using Sonic Scanner, which has deeper depth of investigation (DOI) than that of the RST, indicates that a compressional wave velocity after the production test was not detected from middle to deeper section of the perforated interval. This probably corresponds to the existence of gas which was produced by the decomposition of the methane hydrates. The middle to deeper section of the perforated interval shows higher initial permeability due to the moderate hydrate saturation rate (around 60-70%). Hence, the dissociation of hydrates dominantly occurs in the deeper section of the perforated interval which coincides with the numerical simulation results. On the contrast, a shear-wave velocity before/after the production test was detected in the entire part of the perforated interval. In particular, at middle to deeper section of the perforated interval, the velocity significantly decreases that corresponds to the decrease of the hydrate saturation rate from 70 % to 20 % according to a relationship between the hydrate saturation rate and the velocity data. Despite of a large amount of the dissociation of the hydrates, formation framework of sands (sand bonding) is still remained at the deeper DOI (54.1 cm from the formation). 12049 Numerical simulation of dissociation of methane hydrate in response to pressure decrease in sediment by periodic uplifting events International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Shusaku Goto, Osamu Matsubayashi(National Institute of Advanced Industrial Science and Technology), Sadao Nagakubo(JOGEMC) Methane Hydrate Research Project Team In marine sedimentary environment, dissociation of methane hydrate (MH) in sediment occurs when temperature of the sediment increases from MH stability to gas-water. Dissociation of MH also occurs when pressure in sediment decreases from MH stability to gas-water. Characteristics of dissociation of MH in marine sedimentary environment by increase of bottom-water have been investigated in several studies. In the present study, we present a one-dimensional numerical model of dissociation of pore-space MH in sandy sediment in response to depressurization by periodic uplifting events. In this model, the pressure in sediment is assumed as hydrostatic. The upper boundary (seafloor) is set to a constant temperature. At the lower boundary, a constant heat flow is assumed. This model treats the effect of latent heat on dissociation of MH in the calculation. We apply this model to investigate characteristics of dissociation of MH and the effects of the dissociation of MH on the sub-bottom thermal regime in response to depressurization by periodic uplift events that occur every 100 years. For the numerical computation, different values of initial water depth, saturation of MH, displacement of uplift and thickness of pore-space MH layer in sediment are assigned to investigate how these parameters contribute to the dissociation of MH. When pressure of a layer decreases from MH stability to gas-water by uplift, temperature of the sediment decreases to the temperature of hydrate stability boundary at that depth by the endothermic dissociation of MH. After that, dissociation of MH progresses at the base of gas hydrate stability (BGHS) at the depth until the next occurrence of uplift. The endothermic dissociation of MH at BGHS acts as self-cooling of the sediment and consequently works to slow dissociation of MH. Dissociation of MH becomes faster for the model of shallower initial water depth, larger displacement, or low MH saturation. On the other hand, thickness of pore-space MH layer only controls completion time of dissociation of MH. This study is supported by MH21, Research consortium for methane hydrate resource in Japan. 12048 Mallik 2L-38 – Applications of Elemental Capture Spectroscopy International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Doug Murray(Schlumberger), Satoshi Noguchi, Tetsuya Fujii, Koji Yamamoto(JOGMEC), Scott R. Dallimore(Geological Survey of Canada, Natural Resources Canada) Methane Hydrate Research Project Team An important parameter for reservoir characterization and simulation is formation permeability. A reasonable understanding of this property, both original in-situ permeability and for the condition of no hydrate, are key to the development of future gas hydrate production. The paper highlights the use and benefits of nuclear elemental spectroscopy to compute key gas hydrate reservoir parameters. 12047 Mallik 2L-38 - Hydrate Saturation from Resistivity Anisotropy International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Doug Murray(Schlumberger), Satoshi Noguchi, Tetsuya Fujii, Koji Yamamoto(JOGMEC), Scott R. Dallimore(Geological Survey of Canada, Natural Resources Canada) Methane Hydrate Research Project Team Conductive shale laminations have a profound effect on conventional resistivity logs, causing them to read significantly lower than the high resistivity sand layers and leads to pessimistic estimates of water saturation. It is shown that in thinly laminated reservoirs, with necessary resistivity anisotropy measurements and workflows, correct resistivity based estimates of water saturation can be computed that match those computed from density-magnetic resonance porosity deficit. 12046 Development of a Mechanical and Thermal Earth Model for the 2007/2008 Mallik Gas Hydrates Production Tests International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Richard Birchwood , Osman Hamid , Rishi Singh , Shiela Noeth (Schlumberger), Koji Yamamoto (JOGMEC) Methane Hydrate Research Project Team The formation specific heat capacity and thermal conductivity were predicted using effective medium methods. The latter compared favorably with an independent estimate of the thermal conductivity deduced from the measured geothermal gradient. Coal beds were seen to act as insulators with high heat capacities and could play an important role in altering heat transfer during gas hydrate production. Thermal properties were calculated for a wide variety of hypothetical states that could occur during gas hydrate production. It was found that the generation of methane gas or ice in the pore space could strongly affect thermal properties. Such effects are important for the design of the production scheme because they influence the efficiency of heat transport and the occurrence of formation damage by ice formation and gas hydrate re-association. 12045 The Workflow for Evaluation of Fault Re-Activation during Methane Hydrate Production Test in Nankai Trough International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Koji Yamamoto (JOGMEC), Kaibin Qiu, Yingru Chen, Richard Birchwood, Wu Chuan(Schlumberger) Methane Hydrate Research Project Team Through integration of data from multi-disciplines, the workflow provides a solid approach to evaluate the potential for fault re-activation that might occur in the production test in the Nankai Trough. The evaluation will also help to develop recommendations on optimizing production to minimize the potential risk of fault reactivation and to improve operational safety. 12044 Marine production test plan in the Eastrn Nankai Trough International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Koji Yamamoto (JOGMEC) Methane Hydrate Research Project Team The concept of the first test is similar to the drill stem test (DST) in exploration wells for oil and gas, but the flow duration is longer and complex downhole devices will be run below the seafloor. The plan consists of the drilling of one production well (vertical well) with a few monitoring wells by a deepwater drilling vessel. Intensive site survey including environmental surveys of the area will be done in the fiscal 2010. The most of the drilling operation is planned in FY2011 with coring and logging programs, and downhole monitoring devices will be installed in the wells. The completion of the production well and flow test is planned one year after the FY2011 drilling. The sand control devices and downhole production devices will be set in the hole, and one to several weeks of flow test by depressurization will be conducted. Monitoring works for gas hydrate dissociation through monitoring wells and seismic surveys, and environmental impact monitoring will associate the gas production operation. 12043 Geomechanics and well completion studies for the 2007/2008 Mallik methane hydrate production test International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Koji Yamamoto (JOGMEC) Methane Hydrate Research Project Team To depressurize the formation, electrical submersible pump (ESP) was adopted. The major concerns of the design were controllability of drawdown due to the uncertainty of the liquid production rate, flow assurance through the prevention of methane hydrate re-association and freeze of water, and tolerance against the solid production. Also environmental regulation influenced the design of the system. We made different designs of test strength in 2007 and 2008 due to match with environmental requests. To prevent the gas hydrate re-association, hydrate inhibitor injection (2007) and downhole induction heater (2008) were used. Data and sample gathering is another important element of the design for this scientific program. Pressure and temperature are measured in the bottom hole with several surface monitoring and sampling. 12042 Objectives and operation overview of the 2007/2008 Mallik Gas Hydrates Production Tests International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Koji Yamamoto (JOGMEC), Scott R. Dallimore(Geological Survey of Canada, Natural Resources Canada) Methane Hydrate Research Project Team In the 2007, the production well was drilled and completed, and the short term production was attempted. Around 4MPa drawdown from original 11MPa to 7MPa was achieved and 830Nm3 of gas was produced during twelve and half-hour term, but the severe sand production prevented further operation. One year later and after the installation of sand control devices, six straight day pumping operation lead to the maximum 7MPa drawdown and 13,000Nm3. The pressure and temperature data obtained in the bottom hole and carbon isotope data proved that the origin of the gas is gas hydrate. Environmental protection is one of most critical factors on the well and completion design. Also the obtaining scientific data is another high priority point of the operation. 12041 Development of Models for Methane Leakage and Discharge of Treated Production Water International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Syunji Sukizaki, Tomomi Eriguchi(日MBRIJ Co., Ltd.), Yasuo Ishihara(Japan NUS Co., Ltd.), Kizaburo Nakata(Tokai University), P.D. Yapa (Clarkson University), Atsuhiro Hirata(ENAA), Nao Arata (JOGMEC) Methane Hydrate Research Project Team . Considering the fact that Japan's Methane Hydrate R&D Program is an attempt placed at the foremost position of the world in exploiting methane hydrate as a new natural gas resource for Japan and that the object sea area is an area of great depth exceeding 1,000m, we are well aware that there are a lot of unknown challenges to be clarified hereafter, in developing this study. Moreover, since top priority is given to assessment of environmental impact and public acceptability, in the implementation of a large-scale national project (including R&D) in recent years, we understand that the research activities of the Environmental Impact Assessment Group have an important mission to achieve in that respect. Before developing a methane hydrate resource, it is important in the environmental impact assessment process to predict and evaluate the potential effect of leaked methane to the marine environment. For this reason, we have started to examine the methodology available to predict and assess this impact. We examined numerical models that are considered effective at predicting and evaluating the behaviors of methane in the aquatic environment (Fig.1). In order to further develop these models, the model parameter and observation data were required to the model refine and validation of the model results. Data on the methane flux and the environmental factors involved in the phase changes of methane (dissolved oxygen, hydrogen sulfide, and water temperature) at the benthic boundary layer are essential. Therefore, we prepared equipment to measure the in situ methane flux in the marine environment. As for the development of simulation model which predict the environmental impacts of the discharge of treated production water during methane hydrate dissociation, based on the existing literature and the surveyed results, the prototype physical model were established to assess the diffusion process of the water which released from the seabed or water column. By using this physical model, researchers can execute trial simulations considering seafloor topography and analyze the onsite marine environment properties. We managed the information obtained from these surveys and studies by constructing a database with storage to server. This study has been conducted a part of the research undertaken by Research Consortium for Methane Hydrate Resources in Japan (MH21). 12040 The effect of particle-size distribution on methane hydrate formation in sediments International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Toshiyasu Ukita (JOGMEC), Hailong Lu(National Research Council of Canada), Satoshi Noguchi, Tadaaki Shimada Methane Hydrate Research Project Team Natural gas hydrate occurs in sediments, subject to the influence of the properties of sediments. Studies on natural gas hydrate have found that hydrate saturation in sediments are closely related to sediment type: comparatively enriched in sands but poorly accumulated in fine sediments. However, the knowledge about sediment control on hydrate saturation in sediments is still limited and the mechanism is not yet understood. This research investigated the possible factors involved in sediment control on hydrate saturation using an experimental approach. 12039 Geophysical Study and Well Location Selection in the Mackenzie Delta International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Tatsuo Saeki (JOGMEC), Gilles Bellefleur(Geological Survey of Canada) Methane Hydrate Research Project Team It is difficult to detect explicit seismic evidences showing methane hydrate occurrences in permafrost areas from seismic data, such as “Bottom Simulating Reflectors (BSRs)” in offshore seismic data, except flat seismic reflectors reported as “land BSRs” occurring at bases of methane hydrate stability zones have been. On the other hand, from the view point of resource exploration, experiences in the eastern Nankai Trough taught that 3D seismic data could provide additional useful information relating methane hydrate bearing layers including reservoir character, methane hydrate concentration and some others. Onshore 3D seismic data acquired in and around the Mallik field was utilized to comprehend geological and geophysical conditions prior to the production test in 2007-2008. As a regional interpretation, the time slice in the Kugmalit formation (Oligocene) visualized that the Mallik field was located at the local highest in one of fault blocks along the axis of the anticline divided by cross faults. It suggested that migration of methane gas to the Mallik field might occur due to structural control. Detailed interpretation of 5 key horizons ( seismic reflectors correlated to methane hydrate bearing zones identified in existing wells: L-38, 2L-38, 3L-38, 4L-38 and 5L-38 ) was carried out in the limited area around wells ( 1.2km x 1.8km ). In each horizon, characteristic high amplitude anomaly trends suggesting distributions of fluvial or deltaic sands saturated with methane hydrates were recognized and it was revealed that existing wells had been located along the trends. The trends were considered to be a significant guide to discuss about the location of candidate for the production test, and the existing well was re-used as the test site finally. Acknowledgement: This study was carried out in the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) with the cooperation of National Resources Canada (NRCan). The authors express their gratitude to the METI, MH21 Research Consortium, JOGMEC and NRCan for the permission to publish the results of this study. 12038 Delineation of Methane Hydrate Concentrated Zones in the eastern Nankai Trough International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Tatsuo Saeki (JOGMEC) Methane Hydrate Research Project Team In order to comprehend distribution of methane hydrates expected to be future energy resources, “Research Consortium for Methane Hydrate Resources in Japan” (MH21) had carried out geological and geophysical investigations in the eastern Nankai Trough since 2001 under the support of the Ministry of Economy, Trade and Industry (METI). Results of multi-well drillings and 2D/3D reflection seismic surveys ( METI 2D seismic survey “Tokai-oki to Kumano-nada” [2001-2002], METI 3D seismic survey “Tokai-oki to Kumano-nada” [2002], and METI Exploratory Test Wells Tokai-oki to Kumano-nada” [2004] ) revealed that methane hydrate concentrated zones comprised of turbidite sand bodies as reservoirs, existed separately in portions of methane hydrate distributed areas suggested by Bottom Simulating Reflectors (BSRs).The methane hydrate concentrated zone is a complex of methane hydrate concentrated sediments, and they are expected as possible resource field such as prospects or leads in conventional oil and gas explorations. The workflow for delineation of methane hydrate concentrated zones using reflection 3D seismic data was established and the following 4 indicators are considered to be essential: (1) BSRs, (2) turbidite sequence (above BSRs), (3) strong seismic reflectors and (4) relatively higher interval velocity. (1) suggests methane hydrate occurrence and (2) can be utilized to delineate good reservoir for methane hydrate concentration, therefore the integration of (1) and (2) can indicate candidates for methane hydrate concentrated zones. (3) and (4) are indicators as seismic properties to evaluate methane hydrates concentrations. More than 10 possible methane hydrate concentrated zones in the eastern Nankai Trough were delineated by utilizing the above workflow. The total amount of methane gas in place in delineated methane hydrate concentrated zones in the area was estimated to be 20tcf using the probabilistic approach. Currently reservoir characterizations are ongoing in the candidate areas for the offshore production test. Acknowledgement: This study was carried out in the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium). The authors express their gratitude to the METI, MH21 Research Consortium and JOGMEC for the permission to publish the results of this study. 12037 Completion Design and Technical Issues – 1st Methane Hydrate Offshore Production Test in the Nankai Trough- International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Maki Matsuzawa, Koji Yamamoto, Norihito Inada, Yoshihiro Teao(JOGMEC), Masahiro Nakamura, Keiichi Kishi(Japan Drilling Co., Ltd.) Methane Hydrate Research Project Team As a part of the phase two program of MH21 research project, the first production test of an offshore methane hydrate (MH) in Japan will be performed in the Japanese fiscal year of 2012. The main objective of the first test is to evaluate the productivity of deepwater well for MH dissociated methane gas by deducting in-situ formation pressure from a MH concentrated zone. The duration of the first test is set to be one to a few weeks to collect necessary data to achieve the objective. The conceptual design of the well completion for the test is similar to the drill stem test of conventional oil and gas wells. The design work bases on the experience of the second land production test performed in the Mallik field in Canada in 2007-2008. The principle of the bottom hole pressure reduction is to drop the fluid level of the well and keep it stable by an electric submersible pump that is same way of the depressurization operation of the second land production test. In the plan, a dynamic positioning controlled drilling unit will be employed. By this reason, as well as motion of the vessel the emergency riser disconnection operation should be taken into account in the completion design for the cases of the test operation termination during gas production test caused by a weather and/or sea current conditions, and the positioning system failures. The target bottom hole pressure for the test is set to be 3MPa in which significantly high drawdown against the formation pressure is applied. The pressure and temperature of produced gas and water during the test will be lower than those of conventional natural gas production. The re-hydration of produced fluids in the well during the test and the volume of produced water cause concerns of the flow assurance and influence test conditions such as the maximum flow rate, the test duration limit, the depressurization ratio, and the sand face completion method. Also environmental impacts should be considered in the design of the test program and devices. The ability of production devices constrains the conditions, too. The downhole testing assembly for the test will consist of a subsea test tree, a retrievable packer, an electric submersible pump, a down hole heater, temperature / pressure sensors, and so on. Safe, reliable, and efficient operations of the test are high priority conditions of the design of the assembly 12036 DNA markers associated with methane leakage from the deep sea floor in the eastern Nankai Trough International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Kouki Yoshida, Noriko Okita(Taisei Co., Ltd.), Hiroyuki Fuse(Shibaura Institute of Technology), Tatsuhiro Fukuba, Teruo Fujii (The University of Tokyo), Syunji Sukizaki(MBRIJ), Atsuhiro Hirata(ENAA), Nao Arata(JOGMEC) Methane Hydrate Research Project Team We studied the DNA markers of uncultured microorganisms in order to develop one of the environmental indicators on methane leakage in deep sea floor. Methane oxidizing bacteria called methanotrophs consume methane as their sole energy and carbon source and are distributed at methane producing sites. Methanotrophs are ubiquitous in soil, fresh water and the open ocean but have not been well characterized in deep-sea hydrocarbon seeps and gas hydrates, where methane is unusually abundant. Our goal in this study was to compare the composition of bacterial and archaeal communities associated with methane seep sediments with those of bacterial and archaeal communities in other marine sediments in the eastern Nankai Trough of Japan in order to identify specific DNA markers for methane leakage in the deep sea. Samples (sediments) were collected from one methane seep location, one mud volcano location and 13 background surface sediment marine locations. Using a PCR-based cloning approach, community DNA was isolated from each location to establish clone libraries for the 16S ribosomal gene and the particulate methane monooxigenase gene (pmoA). Molecular phylogenetic surveys were conducted on each clone sequence to analyze the microbial communities responsible for anaerobic oxidation or aerobic oxidation of methane. The molecular phylogenetic analyses revealed significant diversity of microorganisms associated with different types of environments in the eastern Nankai Trough. In addition, several sequences of the 16S ribosomal gene from anaerobic methanotrophs (ANME) and the pmoA gene from aerobic methanotrophs were detected in surface sediments associated with a methane seep site, although few methanotrophic clones were detected in sediments from other background marine locations. Recently, it has been shown that aerobic methanotrophs coexist with anaerobic bacteria and archaea in close proximity at methane seeps of the Kurosihma Knoll of Japan (Inagaki et al. 2004). Nunoura et al (2006) have shown that group-specific methyl coenzyme M reductase genes (mcrA) from methanotrophic archaea, which is another DNA marker, were detected in anoxic methane seep sediments at the accretionary prism of the Nankai Trough. Phylogenetic analysis of the pmoA gene revealed that the community structures of methanotrophs in gas hydrate environments differed from those in the normal marine sediments in the Gulf of Mexico (Yan et al. 2007). These microbiological studies and our results suggest that specific DNA markers of uncultured methanotrophs may be suitable for the environmental indicator on methane leakage in deep marine sediments. This research was conducted under the auspices of "Research Consortium for Methane Hydrate Resources in Japan"(also known as MH21, URL:http://www.mh21japan.gr.jp). 12035 Environmental Monitoring Systems for Offshore Methane Hydrate Production Tests International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Sadao Nagakubo(JOGMEC), Yuji Awashima(IHI-MU), Tatsuya Yokoyama(OYO Corporation), Koji Yamamoto, Hideo Kobayashi(National Institute of Advanced Industrial Science and Technology() Methane Hydrate Research Project Team To evaluate the severity of MH-specific environmental risk factors for future MH development, it is necessary to monitor the actual data of potential environmental risks of offshore methane hydrate production tests planned in FY2012 and FY2014 in the eastern Nankai Trough. This monitoring should be conducted continuously during and after offshore production tests to understand the events such as methane leakage from the seafloor and seafloor deformation such as subsidence. For appropriate monitoring, new monitoring systems are required. At present, MH21 Research Consortium is developing the following two monitoring systems for the first offshore production test conducted in FY2012: 1) Methane leakage monitoring system that focuses on the increase of dissolved methane concentration in bottom water, 2) Seafloor deformation monitoring system that can detect the seafloor subsidence. 1. Methane leakage monitoring system Because the MH-bearing layer exists at a relatively shallower zone beneath the seafloor, leakage of methane gas from the seafloor around the production well is a concern. The methane leakage monitoring system is used to detect increases of dissolved methane concentration, which is usually accompanied by a release of methane bubbles. This monitoring system is equipped with Improved-METS Sensors. 2. Seafloor deformation monitoring system Taking the duration of first offshore production tests (1 week – 1 month), predicted displacement of subsidence, and the installation and recovery procedures into account, MH21 Research Consortium developed a conceptual design of the seafloor deformation monitoring system. This monitoring system is equipped with two sensors: a tilt-meter and a pressure-sensor. MH21 Research Consortium has already finished the conceptual designs of both monitoring systems. We are conducting detailed design work of these two systems, manufacturing the prototypes, and planning to implement the validation tests in a marine environment with the aim of using them in the first offshore production test. Based on these data acquired by the first offshore production test, we will improve the monitoring systems for the second offshore production test scheduled in FY2014. 12034 Construction of the 3D Reservoir Models for the Eastern Nankai Trough Methane Hydrate Reservoirs International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Akihiko Sato, Hisanao Ouchi, Masanori Kurihara(Japan Oil Engineering Co., Ltd.), Tatsuo Saeki, Koji Yamamoto, Satoshi Noguchi(JOGMEC), Hideo Narita, Jiro Nagao, Kiyofumi Suzuki(National Institute of Advanced Industrial Science and Technology), Yoshihiro Masuda(The University of Tokyo) Methane Hydrate Research Project Team The Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) is planning to conduct production tests targeting methane hydrate (MH) reservoirs located in the Eastern Nankai Trough. Towards the successful implementation of the production tests, MH21 Research Consortium has been evaluating MH reservoirs located in the Eastern Nankai Trough from the viewpoints of geology, geophysics, petrophysics and reservoir/production engineering. Integrating the results of these studies, we have been attempting to construct 3D reservoir models, which have been used to predict the performances of production tests through numerical simulation. This paper presents how we constructed the 3D MH reservoir models integrating the results of the log interpretation, 3D seismic interpretation data core analysis. Eastern Nankai Trough MH reservoirs are composed of alternating beds of sand layers and mud layers in turbidite sediments. First, the frames of the geological models including the faults for the vicinity of the exploratory wells (-1 and -1), were defined rigorously mainly reflecting the 3D seismic interpretation results. The insides of the frames were then divided into multiple grid layers replicating alternating sand and mud layers. The distribution of the properties of each grid layer such as lithology, porosity, permeability and MH saturation were estimated by geostatistical techniques using well log interpretation results as a hard data and seismic attributes (e.g., amplitude and acoustic velocity) as soft data. Finally, the geological models thus constructed were converted to the reservoir models (Figure 1) by incorporating overburden and underburden layers and by specifying initial pressure and temperature. 12033 Environmental risk Assessment of methane hydrate development International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Itsuka Yabe(JOGMEC), Hideo Kobayashi( National Institute of Advanced Industrial Science and Technology), Nao Arata, Sadao Nagakubo, Koji Yamamoto(JOGMEC) Methane Hydrate Research Project Team Environmental Impact Assessment Team of Research consortium for Methane Hydrate Resources in Japan (MH21) has been studying to establish the method for environmental impact assessment (EIA) concerning future MH development by conducting own EIAs at two offshore production tests planned during Phase 2 (2009-2015FY) of Japan’s Methane Hydrate R&D Program. We assume the following events as environmental risk factors concerning MH development, and are currently conducting various researches: (1) methane leakage from the seafloor around the production well, (2) discharge of treated production water into the ocean, (3) seafloor subsidence and (4) submarine landslides (Yamamoto and Nagakubo, 2009). There are still uncertainties about each severity of environmental risk factors and impacts. To evaluate these severities, we are planning to conduct marine surveys and environmental monitoring before/after two offshore production tests. Additionally we are developing and improving numerical models to predict the severities of expected environmental risk factors and impacts (Arata et al., 2009). In order to identify the environmental impacts concerning MH development, we are constructing the conceptual model (as flow charts) which shows the relations between the expected environmental risk factors and the impacts. We are currently constructing the conceptual model for the first offshore production test. However, the temporal and spatial scale of commercial production is different from the offshore production tests. Therefore, we are planning to improve the current conceptual model for future commercial production through monitoring of the two offshore production tests. It is important to set the endpoints for EIA study of future MH development. To clarify the endpoints, we are conducting the interviews to the specialists and expected stakeholders on future MH development in various fields (oil and gas exploration, geology, oceanography, fishery science, marine ecosystem, etc.). We will introduce the current conceptual model and the results of interviews at our presentation. 12032 Environmental Characterization of the Eastern Nankai Trough and Environmental Impact Assessment Studies with MH Development International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Sadao Nagakubo, Nao Arata, Itsuka Yabe, Koji Yamamoto(JOGMEC), Hideo Kobayashi( National Institute of Advanced Industrial Science and Technology) Methane Hydrate Research Project Team The main target in the EIA studies in Phase 2 (FY2009-2015) of Japan's Methane Hydrate R&D Program is to identify the environmental risks with methane hydrate (MH) development and verify these likelihood and consequence through two offshore production tests. Based on the data acquired by the tests, we will propose essential countermeasures against possible environmental concerns with commercial MH production. For preliminary quantitative evaluation of MH specific environmental risks on the tests, it is necessary to understand the natural characteristics and variation of water quality, surface sediment characteristics and composition of marine biota on the eastern Nankai trough (a model field of the Program). Accordingly, MH21 conducted baseline marine surveys in the whole area of the eastern Nankai Trough in Phase 1 and is planning to conduct detailed environmental marine surveys in and around the test fields before and after the tests periodically. Taking these data into account, MH21 has been constructing the numerical models to predict the behavior of leaked methane gas and discharged production water derived from MH dissociation which is treated in advance. In addition, MH21 has developed a simulator to predict the extent of seafloor displacement accompanied with MH production based on the geomechanical test data and so on. What is more, MH21 has been designing monitoring systems to detect methane gas leakage and seafloor displacement around test wells and is planning to monitor these events through the tests. Regarding submarine landslides, we have implemented risk assessment on slope stability around the model field. Based on these analyses, we will select the safe test points where submarine slides would not occur. In our presentation, we will introduce main environmental characteristics of model fields and main research items described in Table 1. 12031 Environmental Impact Assessment Study on Japan's Methane Hydrate R&D Program International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/17 Sadao Nagakubo, Nao Arata, Itsuka Yabe, Koji Yamamoto(JOGMEC), Hideo Kobayashi( National Institute of Advanced Industrial Science and Technology) Methane Hydrate Research Project Team One of the research objectives described in the Japan’s Methane Hydrate R&D Program is “Establishment of an exploitation system complying with environment”. Environmental impact assessment (EIA) on future MH development. Sometimes it might be said that the MH development is dangerous. However the safety and environmental risks on the MH development should be interpreted objectively in consideration of; (1) occurrence condition of target MH-bearing layer, (2) production method, and (3) designs of production system. MH21 Research Consortium drew the following scenario from the results of the Phase 1 of the program; “We could develop the pore-filling type MH in sandy layers by depressurization method using about the same as conventional oil and natural gas development systems. We have verified in a scientific manner about environmental risks when the MH development would be conducted in this scenario. In consequence, at present, we are speculating that the safety and environmental risks of the MH development in the eastern Nankai trough are not thought to be serious from conventional oil and gas production. However we should identify environmental risks peculiar to the MH developments. We assume the following events may be environmental risk factors, and are advancing various researches at present; (1) Methane leakage from the seafloor around the production well, (2) Discharge of treated production water into the ocean, (3) Seafloor subsidence and (4) Submarine landslides However it is uncertain whether these events would occur by the MH development, and also whether the significance would be serious as environmental risk factors. For the comprehensive EIA on the MH development, MH21 Research Consortium started the following research; (1) identification of environmental risks, (2) evaluation of significance of environmental risks, and (3) investigation on mitigation and avoidance plan. In Phase 2 (Figure 1), we will implement the EIA through the two offshore production tests to acquire the environmental data for commercial production.nt is one of the great concerns. 12030 Prediction of Performances of Methane Hydrate Production Tests in the Eastern Nankai Trough International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Masanori Kurihara, Kunihiro Funatsu, Hisanao Ouchi(Japan Oil Engineering Co., Ltd.), Tatsuo Saeki, Koji Yamamoto, Satoshi Noguchi(JOGMEC), Hideo Narita, Jiro Nagao(National Institute of Advanced Industrial Science and Technology), Yoshihiro Masuda(The University of Tokyo) Methane Hydrate Research Project Team The Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) is planning to conduct production tests targeting methane hydrate (MH) reservoirs located in the Eastern Nankai Trough. In the course of the design of the first production test, MH21 Research Consortium has constructed the 3D reservoir models for two candidate areas; the vicinities of α-1 and β-1 wells that were drilled in the 2004 exploratory drilling campaign. These models were constructed integrating the results of seismic interpretation, well log interpretation and core analysis. First of all, ten candidate locations were selected for the production test well, five (α-pt1 through α-pt5) from the α-1 area and five (β-pt1 through β-pt5) from the β-1 area, in view of the producibility of MH suggested by the 3D reservoir model (Figure 1a). The 2D radial models were constructed extracting the reservoir properties from the 3D reservoir model, in order to roughly investigate the difference in the production performance by location. The 30 day test performances were predicted assuming the application of the depressurization method with the bottomhole flowing pressure of 3 MPa as a base case. In addition, several case simulations were conducted to investigate the effects of bottomhole pressure, completion interval and absolute permeability of sand layers on the test behaviors. As depicted in Figure 1b, α-pt1 and α-pt3 showed the better gas producibility in the α-1 area, while β-pt1 and β-pt3 were forecasted to achieve the better production rate in the β-1 area. Four 3D sector models were then constructed representing the small areas including these four locations (Figure 1a). Using these models, the test performances were predicted more rigorously taking account of the effect of the faults, formation dip and lateral heterogeneity. Finally the optimal location of a test well was recommended comprehensively analyzing the results of the above simulation studies. 12029 Analysis of Mallik Methane Hydrate Production Test Results through History Matching Simulation International Symposium on Methane Hydrate Resources - From Mallik to the Nankai Trough - 2010/11/16 Masanori Kurihara, Kunihiro Funatsu, Hisanao Ouchi(Japan Oil Engineering Co., Ltd.) , Tatsuo Saeki, Koji Yamamoto, Tetsuya Fujii(JOGMEC), Hideo Narita, Jiro Nagao(National Institute of Advanced Industrial Science and Technology), Yoshihiro Masuda(The University of Tokyo), Scott R. Dallimore, JF Wright(Geological Survey of Canada, Natural Resources Canada) Methane Hydrate Research Project Team The methane hydrate (MH) production tests were conducted using the depressurization method in the JOGMEC/NRCan/Aurora Mallik production program in April 2007 and in April 2008. In addition to attaining the first and the only successful methane gas production to the surface from a MH reservoir in the world, various data such as wellhead/bottomhole pressure, temperature, gas/water flow rates and the temperature along the casing measured by Distributed Temperature Sensing (DTS) systems were acquired during these tests. The flow rates of gas and water from the reservoir sand face were estimated by the comprehensive analysis of these data. The test results were then analyzed using MH21-HYDRES, a numerical simulator coded especially for gas hydrate reservoirs. Various numerical models were constructed replicating the reservoir/wellbore to rigorously reproduce the fluid flows both in the reservoir and in the wellbore. The reservoir model was tuned through history matching so as to reproduce the flow rates of gas and water estimated in the above, not only by simply adjusting reservoir parameters, but by introducing the concept of the improvement/reduction of near-wellbore permeability reflecting the creation/plugging of high permeability zones associated with the sand production (Figure 1). Furthermore, the wellbore models clarified the movement of the produced water in the production string. These series of history matching simulation studies clarified the mechanisms of MH dissociation and production during the tests. 12028 Possible migration front of gas-related fluid inferred from 3D seismic in the eastern Nankai Trough Trench Connection: International Symposium on the Deepest Environment on Earth 2010/11/10 Otsuka Hironori, Juichiro Ashi(AORI, The University of Tokyo), Umito Morita, Manabu Tanahashi(National Institute of Advanced Industrial Science and Technology), Sadao Nagakubo(JOGMEC) Methane Hydrate Research Project Team High resolution 3D seismic survey, “Tokai-oki to Kumano-nada”, was conducted for methane hydrate exploration in the eastern Nankai Trough by METI in 2002. Our study focuses on a series of accordion-shaped reflectors with horizontal axis of fold back. They are connected to the edge of BSRs and alternate their polarities at every fold back hinge. We call the reflectors “Foldback Reflectors (FBRs)” in this study. Sedimentary horizons are successive across these series of reflectors with no fault displacement as a general rule. FBR generally corresponds to lateral seismic facies boundary between BSR distribution area and outside of the BSR area. The formation beneath the BSR shows dimmed facies characterized by relatively low amplitude and lack of high frequency components in contrast to outside of the BSR area with normal facies. Seismic velocity analysis suggests that FBRs correspond to velocity boundaries, where the dimmed faceis below the BSR coinsides with relatively low velocity. The polarities of FBRs are also consistent with such velocity changes. Such dimmed facies with low velocity and low amplitude anomaly suggests effects of gas components in the pore water. In this area, FBRs are mostly developed in the well-stratified formation but not in the area of frequent fractures and the area of major lateral lithological change. The observed FBRs are clustered in northern slope of the uplifted outer ridge, whereas few FBRs are developed in the southern slope of the outer ridge with frequent compressive and strike-slip deformations related to major fault systems including the Kodaiba faults and the Tokai faults. The estimated strike directions of each FBRs are probably controlled by the dip direction of crossing formation. Another important character of FBRs is that it never crosses major unconformities into lower strata. In addition, high amplitude layers are sometimes recognized at hinges of foldbacks convex to the outside of the BSR area. These high amplitude layers probably having higher permeability are interpreted as conduits of gas-related fluid from the BSR distribution side to the outside of the BSR area. From these facts, FBR can be regarded as an important proxy indicating fluid distribution and possible migration front of gas-related fluid. This study used data provided by METI, JOGMEC and MH21 Research Consortium for Methane Hydrate Resources in Japan. 12027 Geophysical Characterization of Gas Hydrates Society of Geophysicist (SEG) 「Geophysics」 2010/10/1 Ray Boswell((United States Department of Energy) , Tatsuo Saeki(JOGMEC) Methane Hydrate Research Project Team Recent years have witnessed an array of international field expeditions designed to investigate the nature of Arctic and marine gas-hydrate geologic systems and the potential for gas-hydrate accumulations to be tapped as a future supply of natural gas. At the same time, numerical models designed to assess gas-hydrate reservoir response to production-related or natural perturbations have continued to mature. With regard to resource potential, it now appears that the most promising reservoirs will be those accumulations that are housed at high saturations in sandand sandstone-dominated lithologies at or near the base of gas-hydrate stability. Essential to assessing and realizing this potential will be technologies to effectively survey deepwater shallow sediments to remotely detect and characterize gas-hydrate occurrence. The refined focus of attention on sand and sandstone reservoirs has significant implications for this effort. We now have the opportunity to move gas-hydrate exploration beyond the primary reliance Recent years have witnessed an array of international field expeditions designed to investigate the nature of Arctic and marine gas-hydrate geologic systems and the potential for gas-hydrate accumulations to be tapped as a future supply of natural gas. At the same time, numerical models designed to assess gas-hydrate reservoir response to production-related or natural perturbations have continued to mature. With regard to resource potential, it now appears that the most promising reservoirs will be those accumulations that are housed at high saturations in sandand sandstone-dominated lithologies at or near the base of gas-hydrate stability. Essential to assessing and realizing this potential will be technologies to effectively survey deepwater shallow sediments to remotely detect and characterize gas-hydrate occurrence. The refined focus of attention on sand and sandstone reservoirs has significant implications for this effort. We now have the opportunity to move gas-hydrate exploration beyond the primary reliance on geochemical and geophysical indicators taken from the margins of the gas-hydrate stability zone. Future gas-hydrate exploration will instead incorporate that information into a fuller approach centered on the improved imaging and characterization of discrete prospects. This potential for delineation of specific targets is particularly true for those accumulations that are of sufficient gas-hydrate saturation and thickness to be attractive exploration prospects. Further mitigation of the uncertainties inherent in exploration will be provided through geologic, geophysical, and geochemical data that support the presence of the various elements of the gas-hydrate petroleum system, such as gas and water charge, suitable migration pathways, and porous and permeable reservoir facies. In addition, these emerging geophysical technologies and approaches will contribute critical insight to the assessment of the role of gas hydrates in dynamic natural processes such as carbon cycling and global climate change by more accurately capturing the natural variability in gas-hydrate distribution and concentration, the geologic nature of the enclosing media, and other factors that affect gas-hydrate stability and gas and water mobility. 12014 The continuous velocity analysis in the BSR area for methane hydrate in the offshore area between the southern of central Hokkaido and the Shimokita Peninsula Japan Geoscience Union Meeting 2010 2010/5/24 Takao Inamori, Eiichi Asakawa(JGI, Inc.), Masao Hayashi, Tadaaki Shimada, Tatsuo Saeki(JOGMEC) Methane Hydrate Research Project Team In the eastern offshore area of the Shimokita Peninsula, the Bottom Simulating Reflector (hereafter BSR) was found in the seismic data for the site survey of the drilling training of “Chikyu” conducted by JAMSTEC in 2002. In the drilling training of “Chikyu” by JAMSTEC in 2006, the methane hydrate was found in the core near the sea floor. It is presumed the occurrence of the methane hydrate or methane in this area. On the other hand, the distribution of BSR in the offshore area between the southern of central Hokkaido and the Shimokita Peninsula were interpreted from the former seismic survey data by Hayashi et al. (2010). The amplitude of BSR in this area is not so stronger than that of BSR in the Nankai Trough area. It is presumed that the velocity contrast that generates BSR is small. It is presumed that the saturation of MH is small. We were conducted the continuous velocity analysis of the seismic survey of “Douou Nanpou – Sanriku-oki” which was conducted in this area by METI in fiscal year 2008. This continuous velocity analysis (the velocity analysis interval: every 25m) was executed below the two seconds two-way-time deep from the sea floor. As a result, the reversal of the P wave velocity was found, and the occurrence of the methane hydrate was presumed in this area where the BSRs were found. In addition, the reversal of the P wave velocity was found in the not found BSR area of the primary interpretation. The existence of BSR was faintly intermittently confirmed by the detail BSR interpretation. The P wave velocity evaluation by the continuous velocity analysis was confirmed the effectiveness to detect the BSR which was generated by the contrast of P wave velocity by with or without methane hydrate especially in the weak-amplitude-BSR area. This study is a part of the research results of MH21 project conducted by JOGMEC. We would like to thank METI for permission to use seismic data. We also would like to express special thanks to MH21 consortium for assistance of our study. 12013 The Overview of the Study Plan on Environmental Impact Assessment in phase-2 of The Research Consortium for Methane Hydrate Resources in Japan (MH21) Japan Geoscience Union Meeting 2010 2010/5/24 Sadao Nagakubo, Nao Arata, Koji Yamamoto (JOGMEC), Hideo Kobayashi(National Institute of Advanced Industrial Science and Technology) Methane Hydrate Research Project Team The Japan's Methane Hydrate R&D Program initiated in 2001 has moved in the Phase-2 (FY 2009-2015), and being conducted with members of the Research Consortium for Methane Hydrate Resources in Japan (MH21). In the Phase-2, two times of field gas production tests from methane hydrate sediments will be planed at eastern Nankai-Trough offshore Japan, and environmental impact assessment (EIA) on these tests as well as on future methane hydrate (MH) developments is one of the great concern. For comprehensive EIA on the MH development, we have started following research; (1) Identification of environmental risks, (2) Evaluation on significance of environmental risks, (3) Investigation on avoidance plan or mitigation plan. In a series of this process, we will implement EIA on the two offshore production tests to acquire the environmental data for commercial production. Here we present the research overview related to (1) and (2).(1) Identification of environmental risks. By the results of the Phase 1, we have clarified appropriate type of MH deposits, the production method, and the development system. Depend on these results and restriction such as (a) compliance of domestic law, (b) economical efficiency, (c) consistency with the EIA procedure of production system, the following four risks have been extracted at the moment as the specific environmental risks for MH development; (a) Methane leakage from seafloor, (b) Seafloor deformation, (c) Submarine landslide, (d) Disposed water from MH dissociation. We also have estimated that environmental risks on commercial development of MH concentrated zones at eastern Nankai- Trough are not significant, if pressure reduction method should be taken for gas production method from MH, test sites should be chosen carefully and formation property alternation should be well known (2) Evaluation on significance of identified environmental risks To evaluate properly the significance of these environmental risks, it is necessary to predict and evaluate the environmental impacts before the field test and to monitor the behavior of environmental impact factors through the test. Using the data given by monitoring tools and detailed marine environmental surveys, we will verify our estimation described above that the environmental risks would not significant. The main research items in the Phase-2 are described below. (a)Exposure tests of marine organisms in dissolved methane and methane gas (b)Investigation on the possible methane gas migration paths by 3D seismic surveys (c)Investigation on the possibility of submarine landslide occurrence based on the strength change of MH existing stratum and overburden during the MH dissociation, as well as geological property of MH concentrated zone. (d)Simulation by numerical model to predict the behavior of disposed water derived from dissociation of the MH reservoirs. (e)Investigation on the monitoring procedure of environmental risks for marine ecosystems, methane gas leakage and seafloor deformation. Monitoring items, points, periods and sensor selections should also be carefully considered. 12012 The effect of particle-size distribution on methane hydarte formation in sediments Japan Geoscience Union Meeting 2010 2010/5/24 Toshiyasu Ukita, Satoshi Noguchi, Tadaaki Shimada(JOGMEC), Hailong Lu(National research Council of Canada) Methane Hydrate Research Project Team Except for those occurring at sea floor, natural gas hydrates exist in sediments no matter on continental slope or in permafrost. As a result the formation of gas hydrate is subject to the influence of sediments. Although natural sediments are complex in composition, the clarification of sediments is generally based on their particle size distribution. The address to how sediments control the saturation of hydrate in sediments is crucial for hydrate exploration and resource evaluation. As a continuation of our previous studies about sediment control on hydrate formation, further investigations have been carried out for elucidating the mechanism of gas hydrate in natural sediments. In addition to the work on the relationship between hydrate saturation and sediment type, the current research investigated the sorting effect on hydrate saturation. Sorting value is used for describing the particle size distribution of a sediment, and it has been reported that gas hydrate were preferentially enriched in well-sorted sediments. However how the sorting effect plays on hydrate saturation has not been well understood yet. This research is aimed at elucidating this effect by an experimental approach. For deciphering the fundamental mechanisms that control the hydrate saturation in sediments, the proton relaxation times of water in sediments were studied with NMR (Nuclear Magnetic Resonance Spectroscopy). 12011 Lipids distributions in methane hydrate bearing sediments of the Nankai Trough by comprehensive two dimensional gas chromatographic analysis Japan Geoscience Union Meeting 2010 2010/5/24 Miki Amo, Ryuko Izawa, Tadaaki Shimada (Japan Oil, Gas and Methane Hydrate Research Project Team Lipids analyses were done using comprehensive two dimensional gas chromatography (GC x GC) to clarify the bacterial communities and activities with drilled sediment cores of methane hydrate (MH) zone in the Nankai Trough. GC x GC has two capillary columns with different stationary phases. The separation power of the first column is converted into the second column, such that compounds not resolved by the first column. In this study, we attempted to separate and identify biomarkers in the sediment cores by GC x GC-MS. We also compared lipids distributions of surface sediment with those of hydrate bearing zone at three locations, Tokai-oki, Daini-Atsumi knoll and Kumano-nada. The sediment samples were collected from Tokai-oki, Daini-Atsumi knoll and Kumano-nada with METI exploratory well in 2004. The lipids were extracted by methanol/dichloromethane, and then extract was saponified with 0.5 mol KOH/methanol. The neutral fraction was converted to trimethylsilyl esters (TMS) by BSTFA. The TMS-derivatives were analyzed using a ZOEX KT2006 comprehensive GC x GC-qMS equipped with fused silica column BPX-5 and BPX-50. The neutral lipids fractions of all samples mainly consist of n-alkanes, acyclic isoprenoids, n-alcohols, sterols and hopanols. Although the neutral lipids compositions in MH bearing zone were comparatively similar between at Tokai-oki and Daini-Atsumi knoll, those at Kumano-nada was different from those at others. 2,6,10,15,19-pentamethylicosane (PMI) were separated from any other peaks in all samples. The presence of PMI in recent and in ancient sediments has been used as a marker of methanogenic activity probably representing highly reducing conditions. Relative intensity of PMI in MH bearing zone was significantly lower at Kumano-nada than at other two locations. Several hopanols, which indicated bacterial activity, such as 17,21-bishomohopanol, 17,21-homohopanol and anhydrobacteriohopanetetrol were detected in all sediment samples. Similar distributions of hopanols were shown in samples at Tokai-oki and Daini-Atsumi knoll. Many different hopanols were detected in samples at Kumano-nada. These might reflect the differences of bacterial activity and depositional environment of each location. 12010 The distribution of BSR related to methane hydrate, offshore Japan Japan Geoscience Union Meeting 2010 2010/5/24 Masao Hayashi, Tatsuo Saeki, Satoshi Noguchi(JOGMEC), Takao Inamori(JGI, Inc.) Methane Hydrate Research Project Team A comprehensive research into methane hydrate (MH) in the eastern Nankai Trough has started since 2001 through implementation of 3D seismic survey and drilling of many exploratory wells. These activities have brought important knowledge especially on the seismic attributes related to the concentration of MH as well as the observation of unreported subtle BSR in the area. Based on this new understanding, the research consortium “MH21” organized by METI has decided that the BSR map published in 2000 by a group comprised of JNOC (at present, JOGMEC) and 10 private sectors should be revised during the Phase-1 of this national MH research program. The resources assessment group supported by JOGMEC has completed the investigation of BSR for the archived marine seismic data acquired by the Government since 1971, in the light of advanced knowledge about the appearance of it on the seismic sections. Detailed velocity analysis with extensive high density has indicated that BSRs in the Sea of Okhotsk and in the Sea of Japan may represent so called Gas Hydrate Stability Zone (GHSZ), though they appear at very shallow depth as 200msec below the sea floor, comparing to the deeper depth as 500msec to 700msec in the Pacific side. It is proposed that the difference of terrestrial heat flow caused by the geotectonic setting of Japanese Islands may bring the remarkable disparity in GHSZ, which will be important for the future exploration of MH in Japan. The current study has revealed that the areal extent of BSR in offshore Japan is 122,000km2, revising the figure 44,000km2 reported in 2000, and has categorized the interpreted BSR into 4 according to the magnitude of delineated characteristics. 12008 Possible Occurrences of Gas Hydrates in Permafrost at the Mallik Site of Mackenzie Delta in Northwest Territories, Canada Japan Geoscience Union Meeting 2010 2010/5/24 Sadao Nagakubo, Tokujiro Takayama(JOGMEC) Methane Hydrate Research Project Team In 2002, an onshore gas hydrate production test by hot water circulation method was conducted at the Mallik site of Mackenzie Delta in Northwest Territories, Canada. The production test tried to extract methane gas from gas hydrate-bearing layers and became the first success in the world (Yamamoto, 2009).Three wells that were called 3L-38, 4L-38, and 5L-38 were drilled for the production test, and DTS (Distributed Temperature Sensor)s were installed along casing pipes to measure the vertical temperature before/during/after the production test. The measurement was continued for almost one and a half year after the production test. It is estimated by DTS and logging data that permafrost layers are distributed up to approx. 600m depth below ground. Mud logging data of all three wells while the drillings show high hydrocarbon (mainly methane) concentrations (methane sources) in mud at the following depth below ground; (1)100-130m interval, (2)600-700m interval (expected depth because of hole washout) and (3)900-1,100m interval. It has been recognized that methane source at 900-1,100m interval corresponded with gas hydrate-bearing layers by logging and coring data, and the lower part of gas hydrate-bearing layers became target zones of the production test. In case of the methane source at 100-130m interval, it is unlikely that the methane in mud is derived from dissolved methane in the formation water because the amount of methane is large. The C1/(C2+C3) in mud is over 100 as well as the methane source at 900-1,100m interval. The top of gas hydrate stability zone calculated by gas hydrate equilibrium is estimated to be at 190m depth. Therefore the methane source is speculated as a gas pocket, however, DTS data during/after the production test shows lowering of temperature at 100-130m interval. This could cause dissociation of gas hydrates (e.g. Chuvilin et al., 1998). Such a lot of examples of metastable gas hydrate at shallower depth were reported in the permafrost area in Russia, and there is an indication of metastable gas hydrates at other borehole of the Mallik site (Dallimore and Collett, 1995).The methane source at 600-700m interval is also unlikely to derive from dissolved methane. The depth estimation of mud logging data is calculated by the mud volume in open-hole and casing pipes, however, it is impossible to calculate the correct depth at this interval because of terrible hole washout. It is estimated that the correct depth should be shallower than 600-700m depth. DTS data during/after the production test shows a lowering of temperature at 570-600m interval. Therefore the existence of gas hydrate is expected at the interval. It is easy to identify the existence of gas hydrates by electrical logging because gas hydrate is a high-resistivity material, however, ice is also a high-resistivity material. Thus we cannot distinguish the hydrates and the ices. Gas hydrates may co-exist with ices in permafrost at 570-600m interval. The C1/(C2+C3) in mud is lower than 100 at this interval. If gas hydrates exist in shallow zones of permafrost which is out of gas hydrate stability zone, the gas hydrates might influence the climatic variation. Furthermore the climatic variation might influence the generation mechanism of the metastable gas hydrates. This study has been conducted as a part of studies of the Research Consortium for Methane Hydrate Resources in Japan. 12007 Numerical simulation of methane hydrate dissociation in response to pressure decrease by periodic uplift Japan Geoscience Union Meeting 2010 2010/5/24 Syusaku Goto, Osamu Matsubayashi(National Institute of Advanced Industrial Science and Technology), Sadao Nagakubo(JOGEMC) Methane Hydrate Research Project Team Several theoretical studies have investigated characteristics of dissociation of MH in marine sedimentary environment by increase of bottom-water. In the present study, we present a numerical model of dissociation of pore-space MH in sandy sediment in response to periodic events of rapid pressure decrease. This model is based on one-dimensional heat conduction equation of uniform physical properties and takes into account the latent heat of formation and dissociation of MH. The pressure in sediment is assumed as hydrostatic. The upper boundary as seafloor is set to a constant temperature. A constant heat flow is supplied in the lower boundary. This model also assumes for the sediment with pore-space MH that when pressure changes from MH stability to gas+water, temperature of the sediment decreases to the temperature of hydrate stability boundary at the decreased pressure by endothermic dissociation of MH. We apply the numerical model to investigate characteristics of dissociation of MH and the effects of the dissociation of MH on the subbottom thermal regime in response to pressure decrease by periodic uplift that occurs every 100 years. For the numerical computation, different values of initial water depth, saturation of MH, displacement of uplift and thickness of pore-space MH layer in sediment are assigned to investigate how these parameters contribute to the dissociation of MH in response to the periodic uplift. Dissociation of MH progresses as follows: In the sediment where the phase change occurs from hydrate to gas+water by uplifting of the formation, endothermic dissociation of MH makes temperature of the sediment decrease to the temperature of hydrate stability boundary at that depth. This endothermic dissociation of MH produces small negative thermal disturbance in the thermal structure at the depth. Then temperature in sediment changes to heal the thermal disturbance. During this process, dissociation of MH progresses at the base of gas hydrate stability (BGHS) at the depth until the next occurrence of uplift. The endothermic dissociation of MH at BGHS decreases temperature of sediment around there. This acts as self-cooling of the sediment and results in slow dissociation of MH. Dissociation of MH becomes faster for the model of shallower initial water depth, larger displacement, or low MH saturation. On the other hand, thickness of pore-space MH sediment layer only controls completion time of dissociation of MH. This study is supported by MH21, Research consortium for methane hydrate resource in Japan. 12006 3-D internal architecture of methane hydrate bearing turbidite channels in the eastern Nankai Trough, Japan 7th International Workshop on Methane Hydrate Research & Development 2010/5/10 Satoshi Noguchi, Naoyuki Shimoda, Osamu Takano, Nobutaka Oikawa, Tatsuo Saeki, Tetsuya Fujii(JOGMEC), Takao Inamori(JGI, Inc.) Methane Hydrate Research Project Team 【Abstract】The reservoir architecture of methane hydrate (MH) bearing turbidite channels in the eastern Nankai Trough, offshore Japan is discussed using a combination of 3-D seismic and well log data. The MH bearing turbidite channels consist of complex patterns of strong seismic reflectors, which exhibit a 3-D internal architecture of the channel complex extending to northeast–southwest direction. According to a seismic sequence stratigraphic analysis, the channel complex can be roughly classified into three depositional sequences. Each depositional sequence results in the different depositional system, which primarily controls the reservoir architecture of the turbidite channels. In the southwestern part of the channel complex around β2 well, the thickness of the turbidite channels is much greater than that of the northeastern part of the channel complex around β1 well. However, the depositional sequence of the northeastern part represents a sand-dominated turbidite system ensuring that the reservoir potential is high despite the relatively smaller thickness of the turbidite channels. For constructing a geological frame model, we examined further details of reservoir characteristics of the geological frame of the channels around β1 well. The bottom frame of several channels is oriented along north-to-south and north-northeast-to-south-southwest directions, which coincide with the distributary patterns of the higher amplitude values in amplitude map. The several magnitudes of these amplitude patterns within the turbidite channels reveal complex stacking patterns of several orders of the flow units. An anomalously high interval velocity between BSR (bottom simulating reflector) and the top of the MH bearing sediments is identified in the northeastern part of the channels. The turbidite sediments in the northeastern side of channels are derived from the north-northeast direction, which is different from the sediments supply systems of the rest of the channels. The different sediments supply system of northeastern side of channels is related to the abundance of coarse sediments, which may lead to the different reservoir architecture of the turbidite channels. This study has been conducted as a part of the research undertaken by the Research Consortium for Methane Hydrate Resources in Japan (MH21)./Keywords: methane hydrate, turbidite, channel, sequence stratigraphy, reservoir characterization 12005 Exploration Activities of Methane Hydrate resources in the eastern Nankai Trough 7th International Workshop on Methane Hydrate Research & Development 2010/5/10 Tatsuo Saeki, Tadaaki Shimada, Satoshi Noguchi (JOGMEC) Methane Hydrate Research Project Team Aiming commercialization of methane hydrate production, the “Research Consortium for Methane Hydrate Resources in Japan” (MH21) has carried out geological and geophysical surveys in the eastern Nankai Trough since 2001 as a Japanese nation project under the support of METI (Ministry of Economy, Trade and Industry). Data and knowledge provided through 2D/3D reflection seismic surveys and the multi-wells drilling campaign (METI 2D seismic survey “Tokai-oki to Kumano-nada” [2001-2002], METI 3D seismic survey “Tokai-oki to Kumano-nada” [2002], and METI Exploratory Test Wells Tokai-oki to Kumano-nada” [2004]) had revealed that methane hydrate concentrated zones, of which reservoir are turbidite sand bodies, exist locally in methane hydrate distribution areas suggested by Bottom Simulating Reflectors (BSRs).In other words, methane hydrate concentrated zones are groups of relatively higher saturated methane hydrate bearing bodies distributed continuously over the large space, and they are distributed partially in methane hydrate bearing zones, therefore, in the view of resource explorations, methane hydrate concentrated zones can be more attractive than other methane hydrate bearing zones. It is expected that methane hydrate concentrated zones can be targets for future offshore productions. Interpretation workflow for delineation of methane hydrate concentrated zones using reflection seismic data consists of identifications regarding following 4 indicators: (1) BSRs, (2) turbidite sequence (above BSRs), (3) strong seismic reflectors and (4) relatively higher interval velocity. First and second indicators can be utilized to delineate candidates of methane hydrate concentrated zones because they suggest methane hydrate occurrences and possible good reservoirs. Moreover, third and forth indicators may mean seismic characters relating to methane hydrates saturations and existences of methane hydrate saturated layers. Methane hydrate concentrated zones proven by multi-wells drilling satisfied above 4 indicators. More than 10 methane hydrate concentrated zones were delineated successfully in the eastern Nankai Trough by utilizing the above workflow and their amounts of methane gas in place were estimated through the probabilistic approach. Current research phase has been shifted to interpretation and analysis work of internal detailed structures and quantitative geophysical properties of methane hydrate concentrated zones in order to plan future offshore production tests. This study has been conducted as a part of the research undertaken by the Research Consortium for Methane Hydrate Resources in Japan (MH21). 12004 THE MONITORING OF THE GAS HYDRATE PRODUCTION TEST IN THE MACKENZIE DELTA 7th International Workshop on Methane Hydrate Research & Development 2010/5/10-12 Takao Inamori(JGI, Inc.), Koji Yamamoto, Tatsuo Saeki(JOGMEC), Gilles Bellefleur(GSC) Methane Hydrate Research Project Team The Research Consortium for Methane Hydrate Resources in Japan (hereafter MH21) and Natural Resources Canada (hereafter NRCan) in Canada jointly conducted the onshore gas hydrate production test at Mackenzie delta, Northwest Territories, Canada in the early April of 2007. Our production test aimed at the production of gas hydrate by depressurizing in the gas hydrate-bearing layer. During the twelve and half hours of the pump operation, at least 830 Sm3 of gas was produced from gas hydrate-bearing formation. Sonic data were acquired at the open-hole after drilling, the cased-hole before the production test, and the cased-hole after the production test by the Sonic Scanner which developed by Schlumberger. This sonic tool is able to acquire the data in the cased hole. The Sonic Scanner data were almost good and detect the P-slowness and S-slowness in all cases except the perforation test interval. S-wave velocity decreased to compare the difference between the before the production test and after from 1092 to 1104 m, because the gas hydrate dissociated at this interval. And P-wave was not detected at the same interval. It will be concluded the decrease of P-wave velocity caused by small amount of the methane free-gas by the dissociation of gas hydrate. The P-wave could not occur because of the drop of P-wave velocity at this zone with lower velocity than sonic wave velocity of water. It will be concluded the gas hydrate-bearing type is matrix-support from the relationships between P-wave velocity, S-wave velocity, P and S wave velocity ratio and the gas hydrate saturation in the Mackenzie delta. Using the relationship between S-wave velocity and gas hydrate saturation, it would be inferred the gas hydrate saturation decreased from over 60% to below 30% around the borehole. This study has been conducted as a part of the research undertaken by the Research Consortium for Methane Hydrate Resources in Japan (MH21). 12003 ROCK PHYSICS MODEL OF METHANE HYDRATE BEARING SEDIMENTS IN THE NANKAI TROUGH AND THE MACKENZIE DELTA 7th International Workshop on Methane Hydrate Research & Development 2010/5/10-12 Takao Inamori(JGI, Inc.), Tatsuo Saeki(JOGMEC) Methane Hydrate Research Project Team It is well known the methane hydrate exists below the sea floor over 500m or the polar region under the frozen ground in the Earth. We made the cross-plot of the methane hydrate and Vp, Vs, or Vp/Vs from the well log data at the eastern Nankai Trough in Japan and the Mackenzie Delta in Canada. We found that as the methane hydrate saturation (Smh) increases, Vp and Vs increase, and Vp/Vs decreases from these plots. We discussed the rock physics model of methane hydrate bearing sediments. We calculated Vp, Vs, and Vp/Vs as the function of Smh, based on four imaginary rock physics model of methane hydrate bearing sediments which Helgerud (2001) proposed. From the comparison between the real well sonic data and the calculated results from four models, we inferred that the rock physics model of methane hydrate bearing sediments was matrix-supporting model at both the eastern Nankai Trough and the Mackenzie Delta areas. However, there were some error and difference with the Vp, Vs and Vp/Vs from the matrix-supporting model and real well sonic data between the eastern Nankai Trough and the Mackenzie Delta. We estimated the effect of Vp, Vs, and Vp/Vs for the change of clay content of matrix-supporting model. As the clay content decreases, the Vp and Vs increase, and Vp/Vs decreases. The clay content from well core data corresponds with the calculated Vp, Vs, and Vp/Vs as the function of the Smh and the clay content from the matrix supporting model. In the eastern Nankai Trough, it was inferred that clay content estimated from the logging or core data of wells was approximately 50 to 60 %. Our cross-plots are showed that the Vp, Vs and Vp/Vs values correspond to values of 50 to 60 % clay content on matrix-support model. In Mackenzie Delta in Canada, it was inferred that clay content from the logging and core data of wells was approximately 10 %. Our cross-plots are showed that the Vp, Vs and Vp/Vs values correspond to values of 10 % clay content on matrix-support model. In case of the estimation of Smh from Vp, Vs, and Vp/Vs, we need to consider the geology, especially sand/clay ratio of the methane hydrate bearing sediments. This study has been conducted as a part of the research undertaken by the Research Consortium for Methane Hydrate Resources in Japan (MH21). 12002 Overview of the Research Program on Environmental Impact Assessment for the Marine Production Test in Offshore Japan 7th International Workshop on Methane Hydrate Research & Development 2010/5/10-12 Sadao Nagakubo, Yoshihiro Nakatsuka, Nao Arata, Koji Yamamoto(JOGMEC) , Hideo Kobayashi( National Institute of Advanced Industrial Science and Technology) Methane Hydrate Research Project Team The Research Consortium for Methane Hydrate Resources in Japan (MH21) was established to realize the Japanese Methane Hydrate R&D Program initiated in FY2001. This program has moved into Phase-2 (FY2009-2015), planning to conduct two marine production tests in around offshore Japan. Environmental Impact is one of the great concerns for these offshore production tests and for the commercial production of methane hydrate (MH) in the future. In the first phase of this program (FY2001-2008), Environmental Impact Assessment (EIA) group was organized, aiming to establish an environmentally friendly production system concerned with environmental preservation. Numerical models and monitoring sensors were developed concerning the possibilities of environmental risks such as methane leakage and seafloor deformation in this first phase. Also marine baseline surveys in Eastern Nankai Trough were conducted as one of the model field of this program. In the Phase-2 of this program, main target is to identify the environmental risks and to verify the significance of these identified environmental risks. Also investigation for avoidance plan or mitigation plan is considered. In this series of process, we will implement the EIA on the two offshore production tests to acquire the environmental data for commercial production. In this presentation, we highlight the overview related to identification and verification of the significance of environmental risks. For the identification of environmental risks, appropriate occurrence type of MH deposits, the production method, and the development system was clarified due to the result of Phase-1. By considering the following principles such as; (a) Compliance of Japanese domestic law, (b) Economical efficiency, (c) Consistency with the EIA procedure and production system, four risks has been extracted from the clarified result as specific environmental risks at this moment. Extracted risks are the following; (1) Methane leakage, (2) Seafloor deformation, (3) Submarine landslide, (4) Disposed water from the MH dissociation. Also from the results, we could estimate that environmental risks on commercial development of MH concentrated zone are not significant. BACK 1 2 3 4 5 6 7 8 9 10 NEXT

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