Pore-scale water-gas distribution and gas permeability of natural gas hydrate reservoirs in the South China Sea  

作　　者：Yuxuan Xia Derek Elsworth Jianchao Cai Cheng Lu Chao Ma 

机构地区：[1]National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum,Beijing 102249,China [2]Department of Energy and Mineral Engineering,G3 Center and Energy Institute,The Pennsylvania State University,University Park 16802,PA,United States [3]Guangzhou Marine Geological Survey,China Geological Survey,Guangzhou 510075,China [4]Center of Oil&Natural Gas Resource Exploration,China Geological Survey,Beijing 100083,China

出　　处：《Geoscience Frontiers》2024年第4期315-329,共15页地学前缘（英文版）

基　　金：grateful to the National Natural Science Foundation of China(Nos.42302143,42172159,U2244223);China Postdoctoral Science Foundation(No.2023M743870);China Geological Survey Project(No.DD20211350);the Science Foundation of China University of Petroleum,Beijing(No.2462023XKBH002);DE gratefully acknowledges support from the G.Albert Shoemaker endowment.

摘　　要：Challenges in water drainage within natural gas hydrate reservoirs in the Shenhu area of the South China Sea,characterized by high clay content and strong hydrophilicity,significantly hinder natural gas recovery.Examining the effects of gas pressure and liquid/gas saturation on gas permeability reveals essential insights for increasing gas production potential.We report gas displacement experiments on clayey-silt sediment samples,alongside X-ray computed tomography imaging,that reveal critical findings:a notable increase in flow rate and permeability as displacement pressure nears compaction pressure,highlighting the role of pressure management in enhancing recovery;water displacement from varying pore sizes under different pressures,highlighting the influence of pore size on fluid dynamics,and structural changes,including microfracture formation and a significant fracture that enlarges total pore space by about 15%,which collectively suggest methods to improve gas flow and recovery.Moreover,our analysis identifies average throat length,fractal dimension,and succolarity as principal controls on gas permeability,indicating the substantial impact of microstructural properties on extraction efficiency.These outcomes offer valuable strategies for optimizing natural gas hydrate reservoir development in the South China Sea,emphasizing the need for meticulous pressure and saturation control and in applying a deep understanding of microstructural dynamics.

关 键 词：Natural gas hydrate Clayey-silt sediments Gas saturation Gas permeability Microstructure 

分 类 号：P618.13[天文地球—矿床学]