Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance our understanding of methane hydrates in nature. COL assembled a Methane Hydrate Project Science Team with members from academia, industry, and government. This Science Team worked with COL and DOE to develop and host the Methane Hydrate Community Workshop, which surveyed a substantial cross section of the methane hydrate research community for input on the most important research developments in our understanding of methane hydrates in nature and their potential role as an energy resource, a geohazard, and/or as an agent of global climate change. Our understanding of how methane hydrates occur in nature is still growing and evolving, and it is known with certainty that field, laboratory, and modeling studies have contributed greatly to our understanding of hydrates in nature and will continue to be a critical source of the information needed to advance our understanding of methane hydrates.

As gas hydrate energy assessment matures worldwide, emphasis has evolved away from confirmation of the mere presence of gas hydrate to the more complex issue of prospecting for those specific accumulations that are viable resource targets. Gas hydrate exploration now integrates the unique pressure and temperature preconditions for gas hydrate occurrence with those concepts and practices that are the basis for conventional oil and gas exploration. We have aimed to assimilate the lessons learned to date in global gas hydrate exploration to outline a generalized prospecting approach as follows: (1) use existing well and geophysical data to delineate the gas hydrate stability zone (GHSZ), (2) identify and evaluate potential direct indications of hydrate occurrence through evaluation of interval of elevated acoustic velocity and/or seismic events of prospective amplitude and polarity, (3) mitigate geologic risk via regional seismic and stratigraphic facies analysis as well as seismic mapping of amplitude distribution along prospective horizons, and (4) mitigate further prospect risk through assessment of the evidence of gas presence and migration into the GHSZ. Although a wide range of occurrence types might ultimately become viable energy supply options, this approach, which has been tested in only a small number of locations worldwide, has directed prospect evaluation toward those sand-hosted, high-saturation occurrences that were presently considered to have the greatest future commercial potential.

Mass-transport complexes (MTCs) are significant deposits in deepwater settings. The term MTC is a seismic stratigraphic term and can only be applied to features at a scale that can only be completely imaged on volumetrically large seismic surveys. MTCs vary in size and shape, from filling one intraslope basin to several 1000's of square km in unconfined settings. MTCs can vary in thickness from 5 m to 100's of m. Their upper surface is usually irregular, and it commonly eroded by overlying channel and related deposits. Basal surfaces vary from planar, to erosional, to stair step. Internal facies consists of (a) rotated and translated blocks, (b) thrusted blocks, and (c) chaotic facies. Where MTCs have been cored, they consist primarily of clay-rich sediments. In the future, we hope that non-proprietary information on MTCs can be shared in a public forum to improve the geoscience and geotechnical community's understanding of these features. Introduction, Mass-transport complexes (hereafter MTCs) constitute large volumes of sediments in deepwater settings. During the past decade, the extensive interpretation of 3-D seismic data by many petroleum companies has indicated that these deposits are quite common along most deepwater margins. In some basins, individual sequences in the upper Pleistocene may consist of more than 50 percent slides/deformed sediments- for example, deepwater Brunei, 50%, (McGilvery and Cook, 2003); offshore Nile- average of 50%, in some areas up to 90% (Newton et al., 2004); and offshore Trinidad- 50%. MTCs are rarely primary exploration targets in siliciclastic settings. However, these deposits important to study because (1) they constitute important aspects of deepwater sediment fill, (2) they can be important regional seals, and, most critically, (3) understanding their distribution in the shallow subsurface is important both for drilling hazard assessment and field development planning (Shipp et al., 2004). Specifically, the transportation and deformation of MTCs causes the expulsion of water (Piper et al., 1997). As a consequence, these features are commonly overcompacted in the shallow subsurface, so that drilling through these features can significant decrease in drilling time. With rig costs in deepwater averaging $0.25 to 0.4 million/day, shorter drilling times are imperative; accomplishing this requires the detailed study of these features. In addition, understanding the distribution of the upper 10's of m of sediments in the slope is important for deployment of subsea infrastructure. Original Definitions Weimer (1989, 1990) originally defined the term mass transport complex " as sediments that occur at the base of sequences and are overlain and/or onlapped by channel and levee sediments. They commonly overlie an erosional base upfan becoming mounded downfan, are externally mounded in shape, and pinch out laterally"seismic facies (are) hummocky and mounded reflections with poor to fair continuity and variable amplitude" (Figure 1). In its original usage, MTC had a sequence stratigraphic connotation and was used to distinguish it from the generic term "slide." Jackson (1997) defined slides as "a mass movement or descent from failure of earth...or rock under shear stress along one or several surfaces"the moving mass may or may not be greatly deformed, and movement may be rotational or planar."

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The Na Kika Basin in the eastern Gulf of Mexico experienced debris-flow events in geologically recent times (Late Pleistocene to Recent). To assess the potential risk of such debris-flows to the pipelines and structures associated with the Na Kika field development we performed a semi-quantitative risk assessment of the potential impact of debris-flows to the proposed pipeline network. The numerical model BING was used in conjunction with available sediment core information, seismic, and bathymetric data to model a number of sediment failure scenarios. Calibration of the model was done using data from two existing debris flow deposits. After calibration the model was used to simulate specific scenarios, using bathymetric profiles extending from potential source failure areas to proposed pipeline locations. We found that flows with sufficient volumes to impact the proposed engineering structures are generally inconsistent with observed geologic conditions in the area. Introduction This study was motivated by the proposed development of the oil and gas reservoirs located in the greater Na Kika Basin. Figure 1 shows the study area location in the eastern Gulf of Mexico. Seafloor attributes illustrate the complex topography associated with salt domes surrounding the basin (Figure 2). A previous studies of the seafloor in the greater Na Kika Basin identified two subsurface debris flow deposits (GEMS report, 1998). Deep-tow data acquired recently as part of pipeline route evaluation showed a debris flow deposit located on the seafloor in block MC 470 (Figure 3). These observations suggest the Na Kika Basin may be susceptible to future debris flow events that may pose risk to engineered structures in the area, such as pipelines, flexible tubing and anchors. Results of simulations using the numerical model BING (Imran et al., 2001) are used to better understand the risks associated with potential debris flow events in the Na Kika Basin. The inputs parameters for the model are estimated from available field data. These input conditions include information about sediment rheology, flow-path bathymetry (Figure 4), and size of failure. The simulations were performed in two phases. In Phase I we perform a calibration of BING using available seismic and core data from two debris flow deposits located in the Na Kika Basin. In Phase II, we use the calibrated model and fieldderived input parameters to simulate several "attack" scenarios, i.e., forward simulations to determine the conditions at which a pipeline or seafloor structure would be impacted in case a debris-flow occurred. For a given flow-path we explore a range of failure positions and failure volumes and gauge risk to the proposed engineering structures in the area. The present study does not include an assessment of slope stability, or probability of a seafloor failure occurring at a particular location. Instead, our approach is to evaluate what happens to the failed sediment after failure. The results are evaluated vis-Ã -vis the local geological conditions. The volume of failed sediment, the rheological properties of the failed mass, and to a lesser extent the geometry of the failure, influence the runout distance of the flow. In the simulations, we iteratively vary these parameters until a best match is found between the model and field data for both runout distance and thickness, given the rheological conditions and initiation point assigned as input.