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Kenner, LA, United States

Barnard A.,University of Houston | Sager W.W.,University of Houston | Snow J.E.,University of Houston | Max M.D.,Hydrate Energy International
Marine and Petroleum Geology | Year: 2015

We have identified and analyzed the affect of newly identified gas plumes in the water column from the Barbados Accretionary Complex. Multibeam echo soundings from cruise AT21-02 acquired using a Kongsberg EM122 system were used to define a region with several ~600-900m tall gas plumes in the water column directly above cratered hummocky regions of the sea floor having relatively high backscatter at a water depth of ~1500m. The natural gas hydrate stability zone reaches a minimum depth of ~600m in the water column, similar to that of the tallest imaged bubble plumes, which implies hydrate shells on the gas bubbles. Tilting of the plume shows current shear in the water column, with a current direction from the northwest to southeast at 128°, a direction similar to the transport direction of North Atlantic Deep Water in this region. The source of hydrocarbons, determined from existing geochemical data, suggests the gas source was subjacent marine Cretaceous source rocks. North-south trending faults, craters and mud volcanoes associated with the gas plumes point to the presence of a deep plumbing system and indicate that gas is a driver of mud volcanism in this region. The widespread occurrence of seafloor morphology related to venting indicates that subsea emissions from the Barbados Accretionary Complex are substantial. © 2015 Elsevier Ltd. Source

Max M.D.,2457 39th Place NW | Johnson A.H.,Hydrate Energy International
Petroleum Geoscience | Year: 2014

Natural gas hydrate (NGH) is a solid crystalline material composed of water and natural gas (primarily methane) that is stable under conditions of moderately high pressure and moderately low temperature found in permafrost and continental margin sediments. A NGH petroleum system is different in a number of important ways from conventional petroleum systems related to large concentrations of gas and petroleum. The critical elements of the NGH petroleum system are: (1) a gas hydrate stability zone (GHSZ) in which pressure and temperature lie within the field of hydrate stability, creating a thermodynamic trap of suitable thickness for NGH concentrations to form; (2) recent and modern gas flux into the GHSZ along migration pathways; and (3) suitable sediment host sands within the GHSZ. These elements have to be active now and in the recent geological past. Exploration in continental margin sediments includes basin analysis to identify source and host sediment likelihood and disposition, potential reservoir localization using existing seismic analysis tools for locating turbidite sands and estimating NGH saturation, and deposit characterization using drilling and logging. Drilling has validated firstorder seismic analysis techniques for identifying and quantifying NGH using rock physics mechanical models. © 2014 EAGE/The Geological Society of London. Source

Max M.D.,Hydrate Energy International | Johnson A.H.,Hydrate Energy International
Petroleum Geoscience | Year: 2012

Many of the original muddy marine sediments that have compacted to become gas shale could have been in a depositional environment suitable for the formation of natural gas hydrate (NGH), which concentrates gas by a factor of 164 (at STP). Dispersed biogenic NGH in fine-grained continental slope sediments today occurs in sections as thick as 250 m and contains enormous amounts of methane. Concentrated NGH can completely fill porosity in more permeable sediments. Formation of NGH in the early diagenetic history of shale gas sediments may have been the first step in the gas concentration process. NGH that formed in ancient gas shale sediments could have persisted and held the natural gas in place during lithification so long as hydrate remained stable. It is possible that the concentrated gas was held in place until the packing of the clay minerals effectively reduced permeability to a point that the gas released from naturally converting hydrate could not migrate easily. Because NGH creates open porosity upon conversion, a very large part of this gas could have been trapped in the shales before dissociation of the NGH to its component water and gas was completed. An implication for shale gas exploration is that high gas concentrations may not be confined to organic-rich shales but may also be found in any shales that once contained substantial gas hydrates. These include grey shales with lower organic content and more siliceous shales, which respond well to fracking. © 2012 EAGE/Geological Society of London. Source

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