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Communication interventions have broadened from dialogical meaning-making, assessment approaches, to remote-controlled interactive objects. Yet, interpretation of the mostly pre-or protosymbolic, distinctive, and idiosyncratic movements of children with intellectual disabilities (IDs) or profound intellectual and multiple disabilities (PIMD) using computer-based assistive technology (AT), machine learning (ML), and environment data (ED: location, weather indices and time) remain insufficiently unexplored. We introduce a novel behavior inference computer-based communication-aid AT system structured on machine learning (ML) framework to interpret the movements of children with PIMD/IDs using ED. To establish a stable system, our study aimed to train, cross-validate (10-fold), test and compare the classification accuracy performance of ML classifiers (eXtreme gradient boosting [XGB], support vector machine [SVM], random forest [RF], and neural network [NN]) on classifying the 676 movements to 2, 3, or 7 behavior outcome classes using our proposed dataset recalibration (adding ED to movement datasets) with or without Boruta feature selection (53 child characteristics and movements, and ED-related features). Natural-child-caregiver-dyadic interactions observed in 105 single-dyad video-recorded (30-hour) sessions targeted caregiver-interpreted facial, body, and limb movements of 20 8-to 16-year-old children with PIMD/IDs and simultaneously app-and-sensor-collected ED. Classification accuracy variances and the influences of and the interaction among recalibrated dataset, feature selection, classifiers, and classes on the pooled classification accuracy rates were evaluated using three-way ANOVA. Results revealed that Boruta and NN-trained dataset in class 2 and the non-Boruta SVM-trained dataset in class 3 had >76% accuracy rates. Statistically significant effects indicating high classification rates (>60%) were found among movement datasets: with ED, non-Boruta, class 3, SVM, RF, and NN. Similar trends (>69%) were found in class 2, NN, Boruta-trained movement dataset with ED, and SVM and RF, and non-Boruta-trained movement dataset with ED in class 3. These results support our hypotheses that adding environment data to movement datasets, selecting important features using Boruta, using NN, SVM and RF classifiers, and classifying movements to 2 and 3 behavior outcomes can provide >73.3% accuracy rates, a promising performance for a stable ML-based behavior inference communication-aid AT system for children with PIMD/IDs.

BACKGROUND Children with profound intellectual and multiple disabilities (PIMD) or severe motor and intellectual disabilities (SMID) only communicate through movements, vocalizations, body postures, muscle tensions, or facial expressions on a pre- or protosymbolic level. Yet, to the best of our knowledge, there are few systems developed to specifically aid in categorizing and interpreting behaviors of children with PIMD or SMID to facilitate independent communication and mobility. Further, environmental data such as weather variables were found to have associations with human affects and behaviors among typically developing children; however, studies involving children with neurological functioning impairments that affect communication or those who have physical and/or motor disabilities are unexpectedly scarce. OBJECTIVE This paper describes the design and development of the ChildSIDE app, which collects and transmits data associated with children’s behaviors, and linked location and environment information collected from data sources (GPS, iBeacon device, ALPS Sensor, and OpenWeatherMap application programming interface [API]) to the database. The aims of this study were to measure and compare the server/API performance of the app in detecting and transmitting environment data from the data sources to the database, and to categorize the movements associated with each behavior data as the basis for future development and analyses. METHODS This study utilized a cross-sectional observational design by performing multiple single-subject face-to-face and video-recorded sessions among purposively sampled child-caregiver dyads (children diagnosed with PIMD/SMID, or severe or profound intellectual disability and their primary caregivers) from September 2019 to February 2020. To measure the server/API performance of the app in detecting and transmitting data from data sources to the database, frequency distribution and percentages of 31 location and environment data parameters were computed and compared. To categorize which body parts or movements were involved in each behavior, the interrater agreement κ statistic was used. RESULTS The study comprised 150 sessions involving 20 child-caregiver dyads. The app collected 371 individual behavior data, 327 of which had associated location and environment data from data collection sources. The analyses revealed that ChildSIDE had a server/API performance >93% in detecting and transmitting outdoor location (GPS) and environment data (ALPS sensors, OpenWeatherMap API), whereas the performance with iBeacon data was lower (82.3%). Behaviors were manifested mainly through hand (22.8%) and body movements (27.7%), and vocalizations (21.6%). CONCLUSIONS The ChildSIDE app is an effective tool in collecting the behavior data of children with PIMD/SMID. The app showed high server/API performance in detecting outdoor location and environment data from sensors and an online API to the database with a performance rate above 93%. The results of the analysis and categorization of behaviors suggest a need for a system that uses motion capture and trajectory analyses for developing machine- or deep-learning algorithms to predict the needs of children with PIMD/SMID in the future.

Background Children with profound intellectual and multiple disabilities (PIMD) or severe motor and intellectual disabilities (SMID) only communicate through movements, vocalizations, body postures, muscle tensions, or facial expressions on a pre- or protosymbolic level. Yet, to the best of our knowledge, there are few systems developed to specifically aid in categorizing and interpreting behaviors of children with PIMD or SMID to facilitate independent communication and mobility. Further, environmental data such as weather variables were found to have associations with human affects and behaviors among typically developing children; however, studies involving children with neurological functioning impairments that affect communication or those who have physical and/or motor disabilities are unexpectedly scarce. Objective This paper describes the design and development of the ChildSIDE app, which collects and transmits data associated with children’s behaviors, and linked location and environment information collected from data sources (GPS, iBeacon device, ALPS Sensor, and OpenWeatherMap application programming interface [API]) to the database. The aims of this study were to measure and compare the server/API performance of the app in detecting and transmitting environment data from the data sources to the database, and to categorize the movements associated with each behavior data as the basis for future development and analyses. Methods This study utilized a cross-sectional observational design by performing multiple single-subject face-to-face and video-recorded sessions among purposively sampled child-caregiver dyads (children diagnosed with PIMD/SMID, or severe or profound intellectual disability and their primary caregivers) from September 2019 to February 2020. To measure the server/API performance of the app in detecting and transmitting data from data sources to the database, frequency distribution and percentages of 31 location and environment data parameters were computed and compared. To categorize which body parts or movements were involved in each behavior, the interrater agreement κ statistic was used. Results The study comprised 150 sessions involving 20 child-caregiver dyads. The app collected 371 individual behavior data, 327 of which had associated location and environment data from data collection sources. The analyses revealed that ChildSIDE had a server/API performance >93% in detecting and transmitting outdoor location (GPS) and environment data (ALPS sensors, OpenWeatherMap API), whereas the performance with iBeacon data was lower (82.3%). Behaviors were manifested mainly through hand (22.8%) and body movements (27.7%), and vocalizations (21.6%). Conclusions The ChildSIDE app is an effective tool in collecting the behavior data of children with PIMD/SMID. The app showed high server/API performance in detecting outdoor location and environment data from sensors and an online API to the database with a performance rate above 93%. The results of the analysis and categorization of behaviors suggest a need for a system that uses motion capture and trajectory analyses for developing machine- or deep-learning algorithms to predict the needs of children with PIMD/SMID in the future.

Integrated three-dimensional (3-D) paleomorphologic and sedimentary modeling was used to predict the basin architecture and depositional pattern of Pleistocene forearc basin turbidites in a gas hydrate field along the northeast Nankai Trough, off central Japan. Structural unfolding and stratigraphic decompaction of the targeted stratigraphic unit resulted in successful modeling of the paleobathymetry at the time of deposition. This paleobathymetry was characterized by a simple U-shaped paleominibasin. Subsequent turbidity current modeling on the reconstructed paleobathymetric surface demonstrated morphologically controlled turbidity current behavior and selective turbidite sand distribution within the minibasin, which strongly suggests the development of a confined turbidite system. Among three candidate inflow patterns, a northeasterly inflow pattern was determined as most likely. In this scenario, flow reflection and deflection caused ponding and a concentration of sandy turbidite accumulation in the basin center, which facilitated filling of the minibasin. Such a sedimentary character is undetected by seismic data in the studied gas hydrate reservoir formation because of hydrate-cementation–induced seismic anomalies. Our model suggests that 3-D horizon surfaces mapped from 3-D seismic data along with well-log data can be used to predict paleobasin characteristics and depositional processes in deep-water turbidite systems even if seismic profiles cannot be determined because of the presence of gas hydrates.

The reservoir architecture of methane hydrate (MH) bearing turbidite channels in the eastern Nankai Trough, offshore Japan is evaluated using a combination of 3-D seismic and well data. On the 3-D seismic section, the MH-bearing turbidite channels correspond to complex patterns of strong seismic reflectors, which show the 3-D internal architecture of the channel complex. A seismic-sequence stratigraphic analysis reveals that the channel complex can be roughly classified into three different stages of depositional sequence (upper, middle, and lower). Each depositional sequence results in a different depositional system that primarily controls the reservoir architecture of the turbidite channels. To construct a 3-D facies model, the stacking patterns of the turbidite channels are interpreted, and the reservoir heterogeneities of MH-bearing sediments are discussed. The identified channels at the upper sequence around the β1 well exhibit low-sinuosity channels consisting of various channel widths that range from tens to several hundreds of meters. Paleo-current flow directions of the turbidite channels are typically oriented along the north-northeast-to-south-southwest direction. High-amplitude patterns were identified above the channels along the north-to-south and north-northeast-to-south-southeast directions. These roughly coincide with the paleo-current flow of the turbidite channels. An interval velocity using high-density velocity analysis shows that velocity anomalies (>2000 m/s) are found on the northeastern side of the turbidite channels. The depositional stage of the northeastern side of the turbidite channels exhibits slightly older sediment stages than the depositional stages of the remaining channels. Hence, the velocity anomalies of the northeastern side of the channels are related to the different stages of sediment supply, and this may lead to the different reservoir architectures of the turbidite channels.

MH 21 Research Consortium in Japan is planning to implement a gas production test targeting a methane hydrate (MH) reservoir located in MH concentrated zone in the Eastern Nankai Trough (ENT). Two areas surrounding the exploration wells drilled in different MH concentrated zones in ENT were selected as candidates of the production test area because of the availability of well log analysis and seismic interpretation results. The evaluation studies for these areas have been conducted from the various points of view to implement the test successfully. As one of these studies we constructed the 3D reservoir models for the areas consulting the well log analysis and the seismic interpretation results, and predicted the production test performances through numerical simulation. This paper shows how we constructed the 3D models and what results we obtained thorough numerical simulation.First, the frames of the 3D reservoir models for the vicinity of the candidate wells were constructed by consulting seismic interpretation results. The flames were then divided into multiple layers to reproduce the alternating beds structure of sand and mud reflecting the well log interpretation results. The distributions of reservoir properties of each grid layer were estimated by geostatistical techniques using well log interpretation results as hard data and seismic attributes as soft data. Finally the reservoir models were completed by specifying initial pressure and temperature.The well production test performances were predicted through numerical simulation assuming the application of depressurization method. In addition, case studies were conducted to investigate the effect of various scale heterogeneities on the production test performances. The followings were reveled through these studies :(1) Average gas production rate during 30 day test would be over 50,000 m3/d.(2) Large scale heterogeneities such as faults and reservoir dip would affect production test performances significantly.

In the methane hydrate research project by METI/MH21 consortium, some unconventional data analysis techniques are developed and various types of geophysical surveys have been carried out to estimate the distribution and characteristics of methane hydrate. In this paper, we describe the continuous velocity analysis technique, 2D multi-component seismic survey and 2D deep-towed seismic survey which could give promising results not only for methane hydrates but for conventional oil and gas exploration.The continuous velocity analysis is applied to PSTM gather of 2D/3D seismic data in order to estimate the detailed velocity structure around methane hydrate bearing layer. Especially the high velocity anomaly above BSR is recognized as one of the indication which implies existence of methane hydrate concentrated zone. This velocity analysis technique has been applied for monitoring the oil-sand production with SAGD and it gave the successful results.A 2D multi-component seismic survey was carried out using the RSCS in 2006. It is an ocean bottom cable system employing a series of 3-component geophones connected with submarine optical cable. The resulting PP reflection PSTM sections with the vertical component showed excellent agreement with the 3D survey migrated volume. The PS-converted wave sections with inline horizontal component showed amplitude anomalies around BSR. This fact indicates S-wave velocity anomaly and gives information to estimate the rock physics model.A 2D deep-towed seismic survey was carried out in 1996. Both the source and the hydrophone cable are towed close to the seabed to obtain higher resolution section and velocity profiles compared with 3D marine seismic in the very shallow part. But, we can not recognize BSR clearly on the section because of its insufficient source energy. The high resolution section of the survey has great potential for finding active faults or hydrothermal deposits.

The Japanese Government has acquired regional reconnaissance seismic data in territorial waters since 1969 to evaluate the country's hydrocarbon potential. Total length of seismic lines is about 100,000 km and many surveys cover relatively deep water areas where gas hydrate stability zone (GHSZ) is expected to exist. BSRs related to methane hydrates in the offshore areas surrounding Japan were studied jointly by the group comprised of JNOC (at present, JOGMEC) and 10 private sectors based on these archived seismic data, and the areal extent of BSRs was reported to be 44,000 km2 in 2000.The country's research into methane hydrates has been accelerated since 2001 by establishment of the research consortium (MH21) under administrative guidance of METI. To investigate into methane hydrate, extensive 3D seismic surveys were conducted in the eastern Nankai Trough and many LWD wells were drilled there. Through the exploration campaign, certain new knowledge on seismic attributes related to the concentration of methane hydrates was obtained. In the light of this advanced knowledge about the appearance of BSRs, MH21 has decided that the archived seismic data should be investigated for the comprehensive understanding of methane hydrates as the potential future energy resources. Old seismic data processed suitably for loading in a “work station” was interpreted in the sophisticated system, though the volume of them was very limited.A method of high density velocity analysis was applied to the seismic data which recorded clear BSR appearing at abnormally shallow depth as 200msec below the sea floor in the Sea of Japan and in the Sea of Okhotsk, comparing to 500 to 700 msec in the Pacific side. This may represent that the geotectonic setting of the Japanese Islands controls GHSZ and this understanding seems to be important for the future exploration of MH.Present study has revealed that the areal extent of BSRs in offshore Japan is 122,000 km2.

It is well known that the methane hydrate exists below the sea floor over 500 m 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 increases, Vp and Vs increase, and Vp/Vs decreases from these plots. We discussed the rock physics model of methane hydrate bearing layers. We calculated Vp, Vs, and Vp/Vs as the function of the methane hydrate saturation, based on four imaginary rock physics model of methane hydrate bearing layers. From the comparison between the real well sonic data and the calculated data from four models, we inferred that the rock physics model of methane hydrate bearing layers 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 methane hydrate saturation and the clay content from the matrix supporting model. In case of the estimation of methane hydrate saturation from Vp, Vs, and Vp/Vs, we need to consider the geology, especially sand/clay ratio of the methane hydrate bearing layers.

An integrated sedimentological workflow was applied to the methane-hydrate exploration project in the eastern Nankai Trough area, central Japan, as a useful tool to investigate the distributions and actual volume of methane hydrates. Since previous research revealed that most of the methane hydrates in the eastern Nankai Trough area occur in matrix pores of submarine-fan turbidite sandstones, the facies distribution of turbidite sandstones may be one of the important keys to evaluate the occurrence of methane hydrates. Accordingly, this study conducted a) core facies analysis, b) log facies analysis mainly using FMI, c) depositional sequence division, d) seismic facies analysis on the 2D/3D seismic sections, and e) seismic geomorphological analysis on the 3D seismic survey data to map submarine-fan turbidite facies distributions for 17 depositional sequence horizons in the targeted Pleistocene interval. The obtained facies maps reveal that submarine-fan depositional styles changed throughout Pleistocene from a braided channel type, through small radial fan, trough-fill fan, and muddy sheet fan types, to a channel-levee system type. As the next step, the facies maps of each depositional sequence were overlaid with bottom simulating reflector (BSR) distributions as a proxy of methane hydrates. The overlaid maps indicate that the BSRs occur on feeder channels, distributary channels, and proximal lobes of submarine fans, suggesting that methane hydrates selectively occur in coarser grained portions of a submarine fan. The facies maps were also used for calculation of average net-to-gross ratio of the methane hydrate occurrence zones, as the maps provide information on the spatial distributions of seismic facies class, which has individual value of net-to-gross ratio. Finally, this study analyzed reservoir-scale geologic bodies, such as depositional lobes and braided channels of a submarine fan, using 3D seismic survey data, and constructed a detailed geologic model for simulations of methane-hydrate generation and production.

Summary The Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) has been evaluating methane-hydrate (MH) reservoirs located in the eastern Nankai trough from the viewpoints of geology, geophysics, petrophysics, and reservoir/ production engineering. As one of these studies, we have been predicting gas/water production performances from these MH reservoirs showing diverse characteristics. This paper presents the results of our examinations on the applicability of a variety of MH dissociation/production methods to these MH reservoirs and on the feasibility of future development in terms of gas production and economics. Eastern Nankai trough MH reservoirs, which are composed of alternating beds of sand, silt, and clay in turbidite sediments, have various conditions of clay distribution and of initial pressure, temperature, permeability, and MH saturation. Some of these reservoirs contain MH of high saturation at a certain interval (MH concentrated reservoir), while in the others, MH is deposited sparsely (MH-nonconcentrated reservoir). Detailed numerical reservoir models were constructed for both MH-concentrated and -nonconcentrated reservoirs, consulting the well-log and seismic-interpretation results. MH-dissociation/-production performances were then predicted through numerical simulation, assuming the application of various MH-dissociation methods (such as depressurization, well-bore heating, hot-water huff'n'puff, and hot waterflooding. The simulation studies clarified the difference in the gas production between MH-concentrated and -nonconcentrated reservoirs. These studies also revealed that the permeability not only of sand layers but also of clay layers has a significant effect on the gas productivity from MH-concentrated reservoirs. Furthermore, it was suggested that the hot-water injection was effective when it was applied as a secondary-recovery method after depressurization. Simple economic analyses on the basis of these simulation results exhibited the promise that some MH reservoirs in the Eastern Nankai trough could be developed economically if the well spacing and MH-dissociation/-production methods were designed appropriately.

The Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium), which was organized to attain the exploration and exploitation of methane hydrate (MH) resources, has been evaluating MH reservoirs located in the Eastern Nankai Trough from the viewpoints of geology, geophysics, petrophysics and reservoir/production engineering. As one of these studies, we have been predicting gas/water production performances from these MH reservoirs showing diverse characteristics. This paper presents the results of our examinations on the producibility of gas from MH reservoirs located in the Eastern Nankai Trough by a variety of MH dissociation/production methods and on the feasibility of the future development of MH in terms of gas production and economics.Eastern Nankai Trough MH reservoirs, which are composed of alternating beds of sand, silt and clay in turbidite sediments, have various conditions of clay distribution as well as of initial pressure, temperature, permeability and MH saturation. Some of these reservoirs contain MH of high saturation at a certain interval (MH concentrated reservoirs), while in the others MH is deposited sparsely (MH non-concentrated reservoirs). First, the numerical near well model for one of the typical MH reservoirs was constructed mimicking this alteration of sand, silt and clay layers by simplified grid layer system, which was used for the simulation to clarify the mechanisms of MH dissociation and production by the application of the depressurization method.The detailed numerical reservoir models were then constructed for the vicinity of the wells located both in MH concentrated and in non-concentrated reservoirs, consulting the well log and core interpretation results. MH dissociation/production performances were predicted through numerical simulation assuming the application of various MH dissociation methods such as depressurization, wellbore heating, hot water huff'n'puff and hot water flooding. The simulation studies revealed the difference in the gas production between MH concentrated and non-concentrated reservoirs. These studies also suggested that the methane recovery from MH concentrated reservoirs by depressurization methods ranged from 30 to 60% and that the energy efficiency by thermal methods was very small despite high methane recovery. Furthermore, simple economic analyses on the basis of these simulation results exhibited the promise that some MH reservoirs in the Eastern Nankai Trough could be economically developed if the well spacing and MH dissociation/production methods were appropriately designed.

It is important to understand the relations between the formation of methane hydrate in shallow sediments and seafloor manifestations accompanied by methane discharges to delineate the following issues concerning the exploitation of methane hydrate: (1) establishing methane hydrate exploration method through geological and geochemical surveys of the seafloor; (2) understanding methane hydrate system; (3) clarifying relations between methane hydrate-bearing formations and global warming; and, (4) understanding production problems during methane hydrate development. As a preliminary study to solve the above-mentioned issues, we attempted to clarify the relations between methane hydrate-bearing formations and various seafloor manifestations accompanied by methane releases from the seafloor, such as pockmarks and carbonate precipitations, using 3D seismic data in the three survey areas of the eastern Nankai Trough. Bathymetric and seafloor amplitude maps constructed from high-resolution 3D data provided extensive information on the seafloor. We also constructed BSR depth anomaly maps to interpret geothermal gradient and structure of the P-wave velocity in shallow formations because methane hydrate is sensitive to temperature change. It is likely that methane hydrate-bearing formations and seafloor manifestations have a strong relationship with geological migration conduits of methane-bearing fluid in the eastern Nankai Trough, e.g., permeable sandy sediments, and large and shallow faults. New geological and geochemical surveys of the seafloor are required to clarify the relationship.

Abstract The world's first offshore gas production test from methane hydrate deposits was conducted in March 2013, at the test site located on the margin of Daini Atsumi Knoll, off the coasts of Atsumi and Shima peninsulas, in the easten Nankai Trough, of Japan. Approximately 120, 000 cubic meters of methane gas was produced in 6 days using the depressurization technique. The test was a significant advance in Japan's national program to construct the technical base for future commertial methane hydrate resource development. A series of researches for more than 10 years, including two times of onshore production tests in Mallik field and explorations in eastern Nankai Trough, were required to reach the test. This report reviews Japan's research history for methane hydrates.

Abstract OBC (Ocean Bottom Cable) is a common tool used in the exploration of oil and natural gas fields. But its application to deep sea areas still has to be studied. In this paper we introduce the development of a new 4-conponents monitoring system called ‘DSS’ (Deep-sea Seismic System) using multi-component seismic sensors aim to delineate the methane hydrate dissociation zone for the offshore methane hydrate production trial scheduled in FY2012. Back in the year 2006 we developed RSCS (Real-time Seismic Cable System) which was composed of three component gimbaled geophones. The reflection seismic survey trials conducted in the Nankai Trough sea area confirmed the the high quality records that can be obtained with the system. Following the same design concept, we improved the RSCS receiver by reducing its size to 2/3, adopting accelerometers and a hydrophone. The new system was named as ‘DSS’. The receiver case has a protective metallic exterior and the cable is protected with steel-screened armoring, allowing for deployments up to 2,000m water depths and burial using ROV for sub-seabed deployment. This system realizes a unique survey style in which the receivers are left on the seabed between pre-test baseline survey and post-test repeated survey, this interval might be up to 6 months long. The fixed location of the receiver is very important for time-elapsed monitoring surveys. The newly developed DSS, comprising 36 receivers, was deployed and buried on the seabed off the Atsumi Penisnula in August 2012 to conduct a pre-test baseline survey at 1,000m water depths. The pre-test baseline survey was successfully completed and the obtained data was of very high quality. The post-test repeated surveys are planned forApril and August, 2013. Introduction MH21 (Research Consortium for Methane Hydrate Resources in Japan) is planning to carry out the offshore methane hydrate production trial during the FY2012. In this production trial, it is very important to know and understand how the methane hydrate dissociation progresses. The dissociation process progress and changes can be captured only by long-term reflection seismic monitoring which is conducted in intervals as a pre-test survey and a post-test survey, before and after the production trial. The RSCS, developed as a dedicated reflection seismic survey system, was available and its capabilities have been confirmed when we successfully obtained clear BSR (Bottom Simulating Reflector) records during survey trials conducted off Shima cost in 2006. But RSCS receiver size and weight make it very difficult to achieve the requirements for methane hydrate dissociation process monitoring, which requires a receiver interval of 25m at water depths of 1,000m. The estimated cable load was very high and its precise deployment to deep water was too difficult due to the hydrodynamics of the receiver stream. Based on the RSCS design concept, we have developed " DSS" with a more compact and lighter receiver. We have successfully carried out experimental performance trials off-shore in November 2011, and carried out pre-test survey in August 2012. This paper describes about DSS development and the result of pre-test survey.

Abstract We have discussed reservoir architecture of methane hydrate (MH) bearing turbidite channels in the eastern Nankai Trough using 3-D seismic data and well log data. MH bearing turbidite channels exhibit complex patterns of strong reflection comprising patchy-like shape of positive and negative seismic reflectors. The groups of these reflectors obtained by picking represent the internal architecture of the channel complex that can be roughly classified into three depositional sequences. According to a seismic sequence stratigraphic analysis, each depositional sequence results in the different depositional system implying that the reservoir architecture of the turbidite channels varies corresponding to the sedimentary conditions as well as the topographic changes in the study area. Compared with well log data, the thickness of the turbidite channel at ß2 well in the southwestern part of the study area is much greater than that of ß1 well in the northeastern part. However, the depositional sequences of the northeastern part represent sand-dominated turbidite sediments 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 turbidite channels around ß1 well. The identified bottom frame of the several channels is oriented along north-to-south and north-northeast-to-south-southwest directions, which coincide with the directions of paleo-current flows determined by the seismic sequence stratigraphic analysis. An interval velocity between BSR (bottom simulating reflector) and the top of the MH bearing sediments is obtained from a high-density velocity analysis. The distributions of the higher interval velocity are identified above the bottom frame of channels in the northeastern part of the study area. The turbidite sediments in the northeastern side of channels are derived from the north-northeast direction of paleo-current flows, which is different from the sediment supply system compared with those of the northern side to southwestern side of the channels. Thus, the higher velocity anomalies in the northeastern side of the channels may be related to the different coarse sediments supply system which may lead to the different reservoir architecture of the turbidite channels. Introduction The eastern Nankai Trough, extending to southwest-northeast offshore central part of Japan, has been considered to be an attractive target for the potential resource of methane hydrates (MH) from the resource assessment issue as well as the candidate of the exploitation and the production test fields of MH1, 2, 3. In this area, it is widely observed the bottom simulating reflectors (BSR) that are interpreted to represent lower boundary of MH bearing sediments4, 5, 6, 7, 8, 9. Previous studies in the " Nankai Trough?? exploratory test well acquired in 1999 report that MH is developed in the pore space of the unconsolidated turbidite sands in deep submarine-fan sediments10, 11, 12, 13. Based on this exploration result, a 2-D seismic survey in 2001 (2,802 km), 3-D seismic surveys in 2002 (a total area of three survey fields: 1,960 km2), and a multiple well drilling campaign in 2004 were intensively conducted for the purpose of MH research by Japanese Government (Ministry of Economy, Trade and Industry; METI).

Abstract 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 and the 3D seismic data analyses. This paper also discusses how the heterogeneities of reservoirs with a different scale such as a fault, dip and change in permeability and a well location affect the test performances referring to the results of the numerical simulation. 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 for the vicinity of the candidate test wells including the faults 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 by incorporating overburden and underburden layers and by specifying initial pressure and temperature. Well production test performances were then predicted through numerical simulation assuming the application of the depressurization method. In addition to the base case run, case studies were conducted to examine the effects of reservoir heterogeneities and of well locations, which revealed that the large scale heterogeneities such as sealing capability and conductivity of faults and formation dip affected the short term production test performances rather than small scale heterogeneities like a small change in permeability. Furthermore, these studies showed the benefit of numerical simulation for the design of a field well test.

Focal mechanisms around Ontake Volcano, central Japan, were investigated by using the data set obtained by a seismic observation project of the 1986 Joint Seismological Research in Western Nagano Prefecture (JSR'86). The data set included P-wave first motions of aftershocks of the 1984 Western Nagano Prefecture Earthquake (M=6.8) mainly. A total of 556 events was selected for the focal mechanism analysis. The P-wave data from the surrounding university routine networks were also utilized additionally. Four hundred two events were successfully analyzed. Based on the types of focal mechanisms and on the spatial distribution of the events, we classify these events into the following 4 groups: (1) events of strike-slip fault type with a common nodal plane parallel to the ENE-WSW striking nodal plane in the fracture zone of the 1984 main shock; (2) events of reverse fault type in the area of the preexisting earthquake swarm to the northeast of the main shock, in a possible relation with an earthquake swarm activated by the main shock; (3) events of reverse fault type that occurred near the largest aftershock (M=6.2), but are not the continued aftershock sequence of the largest aftershock; (4) events of strike-slip fault type at depths to the easternmost part where no activity had been observed before the operation of JSR'86. The plural types of focal mechanisms obtained and the spatial distribution of foci suggest a complex seismo-tectonic structure that consists of at least 2 kinds of fracturings around Ontake Volcano.

A dense temporary seismograph network was set up in the aftershock area of the 1984 Western Nagano Prefecture Earthquake of M 6.8 by the group for the 1986 Joint Seismological Research in Western Nagano Prefecture. Seismograms of about 1,500 events were obtained during the observation period of 52 days from September 1 to October 22, 1986, and 530 events in and around the aftershock area were located precisely. Extent of the aftershock area is about 20 km in the east-west and about 7 km in the north-south.

The detailed three-dimensional P and S wave velocity structure in the focal region of the 1984 Western Nagano Prefecture Earthquake occurring close to an active volcano, Mt. Ontake, central Japan, is derived from a tomographic inversion of travel time data obtained by the 1986 Joint Seismological Research in Western Nagano Prefecture. The data set includes 7, 693 P-wave and 6, 070 S-wave arrival times observed at 49 stations from 212 local earthquakes and 2 explosions. The velocities in the shallow portion of upper crust are determined at each grid point with its spacing of 1-2 km and good resolutions are obtained from the Earth's surface to a depth of 4 km. There exist strong lateral heterogeneities especially from the surface to a depth of 1 km. The seismic velocity map obtained in the height of 1 km above sea level well corresponds to the maps of surface geology and Bouguer gravity anomaly. This correspondence, however, is not so clear in the deeper layers. And, the greater the depth, the less heterogeneous the velocity structure. The velocity distribution on the fault seems to correspond to the distribution of dislocation and rupture front estimated from an analysis of strong motion and geodetic data: the low velocity region has the large amount of dislocation and the retarded rupture front.

Abstract MH21 Research Consortium of Japan has been evaluating methane hydrate (MH) reservoirs located in the Eastern Nankai Trough from the viewpoints of geology, geophysics, petrophysics and reservoir/production engineering. As one of these studies, we have been predicting gas/water production performances from these MH reservoirs showing diverse characteristics. This paper presents the results of our examinations on the applicability of a variety of MH dissociation/production methods to these MH reservoirs and on the feasibility of the future development in terms of gas production and economics. Eastern Nankai Trough MH reservoirs, which are composed of alternating beds of sand, silt and clay in turbidite sediments, have various conditions of clay distribution as well as of initial pressure, temperature, permeability and MH saturation. Some of these reservoirs contain MH of high saturation at a certain interval (MH concentrated reservoir), while in the others MH is deposited sparsely (MH non-concentrated reservoir). Detailed numerical reservoir models were constructed for both MH concentrated and non-concentrated reservoirs, consulting the well log and seismic interpretation results. MH dissociation/production performances were then predicted through numerical simulation assuming the application of various MH dissociation methods such as depressurization, wellbore heating, hot water huff & puff and hot water flooding. The simulation studies clarified the difference in the gas production between MH concentrated and non-concentrated reservoirs. These studies also revealed that the permeability not only of sand layers but also of clay layers significantly affected the gas productivity from MH concentrated reservoirs. Furthermore, it was suggested that the hot water injection was effective when it was applied as a secondary recovery method after depressurization. Simple economic analysis based on these simulation results exhibited the promise that some MH reservoirs in the Eastern Nankai Trough could be economically developed if the well spacing and MH dissociation/production methods were appropriately designed. Introduction Background. The Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium), which was organized to accomplish the exploration and exploitation of methane hydrate (MH) in the Nankai Trough of offshore Japan, has been implementing a variety of research projects toward the assessment of MH resources, establishment of MH production methods and examination of impacts of MH development on the environment. As part of such research projects, we have been developing the state-of-the-art numerical simulator (MH21-HYDRES) for rigorously predicting MH dissociation and production behaviors both at core and field scales. Using this numerical simulator, we have been implementing numerical simulation studies predicting MH reservoir performances in order to examine the effectiveness of a variety of production methods in terms of the gas producability from MH reservoirs with diverse characteristics (Kurihara et al., 2005a). These studies, however, have been conducted targeting imaginary reservoirs as well as those roughly mimicking Eastern Nankai Trough reservoirs by simplifying reservoir properties.

Abstract Aiming commercialization of methane hydrate development, the Research Consortium for Methane Hydrate Resources in Japan (MH21) has been executing geological and geophysical surveys around the eastern Nankai Trough since 2001 as a national project. Interpretation and analysis studies based on 2D/3D reflection seismic surveys, multi-wells drilling campaign and other geological surveys revealed existences of methane hydrate concentrated zones, of which reservoirs were composed of turbidite sand layers. In the view of resource explorations, methane hydrate concentrated zones are more attractive than other methane hydrate bearing zones because they can reserve much amount of methane hydrate locally. We developed an optimal interpretation workflow for delineation of methane hydrate concentrated zones. The workflow includes evaluation and integration of following four indicators:BSR,Turbidite sequnece,Strong seismic reflector andrelatively higher interval velocity. It enabled in the eastern Nankai Trough to extract more than 10 methane hydrate concentrated zones and evaluate their rock volume successfully.

Abstract Resource assessment of methane hydrate (MH) in the eastern Nankai Trough was conducted through probabilistic approach using 2D/3D seismic data and drilling survey data from METI exploratory test wells " Tokai-oki to Kumano-nada??. We have extracted more than 10 prospective " MH concentrated zones?? characterized by high resistivity in well log, strong seismic reflectors, seismic high velocity, and turbidite deposit delineated by sedimentary facies analysis. The amount of methane gas contained in MH bearing layers was calculated using volumetric method for each zone. Each parameter, such as gross rock volume (GRV), net-to-gross ratio (N/G), MH pore saturation (Sh), porosity, cage occupancy, and volume ratio was given as probabilistic distribution for Monte Carlo simulation, considering the uncertainly of these evaluations. The GRV for each hydrate bearing zones was calculated from both strong seismic amplitude anomaly and velocity anomaly. Time-to-depth conversion was conducted using interval velocity derived from Seismic Vision While Drilling (SVWD). Risk factor was applied for the estimation of the GRV in 2D seismic area considering the uncertainty of seismic interpretation. The N/G was determined based on the relationship between LWD resistivity and grain size in zones with existing wells. Seismic facies map created by sequence stratigraphic approach was also used for the determination of the N/G in zone without well controls. Porosity was estimated using density log, together with calibration by core analysis. The Sh was estimated by the combination of density log and NMR log, together with the calibration by observed gas volume from onboard MH dissociation tests using Pressure Temperature Core Sampler (PTCS). The Sh in zone without well control was estimated using relationship between seismic P-wave interval velocity and Sh from NMR log at well location. Total amount of methane gas in place contained in MH within survey area in the eastern Nankai Trough was estimated to be 40 tcf as Pmean value. Total gas in place for MH concentrated zone was estimated to be 20 tcf (Half of total amount) as Pmean value. Sensitivity analysis indicated that the N/G and Sh have higher sensitivity than other parameters, and they are important for further detail analysis. Introduction Seismic data from the Nankai Trough, offshore central Japan, indicates widespread distribution of bottom simulating reflectors (BSR) 1 that are interpreted to represent lower boundary of methane hydrate (MH) bearing zones. MH in the Nankai Trough is a potential natural gas resource, however, the volume, distribution, and occurrence of MH in this area is poorly understood. In 1999, MH-bearing sand-rich intervals in turbidite fan deposits were recognized from the eastern Nankai Trough based on results of MITI (Ministry of International Trade and Industry) " Nankai Trough?? wells2, 3. Based on this exploration result, the Japanese government inaugurated a 16-year MH exploration program in 2001. As a part of this program, the Ministry of Economy, Trade and Industry (METI), Japan, drilled the " Tokai-oki to Kumano-nada?? exploratory test wells from January to May 2004, in order to obtain data for understanding the occurrence of MH and estimating resource potential4, 5. In this campaign we carried out logging-while-drilling (LWD) at 16 sites, coring at four sites, wireline logging at two sites, and long-term monitoring of formation temperature at single site5,6,7 (Figure 1). Using following data set, we conducted MH resource assessment in the survey area in 2005 and 2006. Figure 2 shows the flow chart of the resource assessment.

[1] To investigate characteristics of a seismogenic out-ofsequence thrust (OOST) imaged as a strong reflection on seismic profiles in the Nankai accretionary prism, we determined acoustic properties of discrete samples from an fossil Nobeoka OOST outcrop under confining pressures, and compared the acoustic properties with those of an active OOST in the Nankai accretionary prism. We observed anisotropy of velocity and attenuation in the hanging wall of Nobeoka OOST attributed to foliation of pelitic-phyllite. In contrast, the footwall is composed of brittlely deformed, chaotic shales and fine sandstones, and velocities in the footwall are lower than those in the hanging wall. Amplitude variation with offset (AVO) modeling utilizing contrasts in P- and S-wave velocities and densities between the hanging wall and footwall of the Nobeoka OOST indicates that fractures filled with overpressured fluid likely account for angle-dependent reflection amplitudes of the active OOST in the Nankai Trough. Citation: Tsuji, T., G. Kimura, S. Okamoto, F. Kono, H. Mochinaga, T. Saeki, and H. Tokuyama (2006), Modern and ancient seismogenic out-ofsequence thrusts in the Nankai accretionary prism: Comparison of laboratory-derived physical properties and seismic reflection data, Geophys. Res. Lett., 33, L18309, doi:10.1029/ 2006GL027025.