含天然气水合物泥质粉砂沉积物电阻率变化规律  

Electrical resistivity change laws of natural gas hydrate bearing clayey-silty sediments

作　　者：骆汀汀 张宸毅 陈雨露 孙翔 杨维好[1] 宋永臣[3] 朱一铭 LUO Tingting;ZHANG Chenyi;CHEN Yulu;SUN Xiang;YANG Weihao;SONG Yongchen;ZHU Yiming(State Key Laboratory of Intelligent Construction and Healthy Operation&Maintenance of Deep Underground Engineering//China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;Institute of Rock and Soil Mechanics//Chinese Academy of Sciences,Wuhan,Hubei 430071,China;Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education//Dalian University of Technology,Dalian,Liaoning 116024,China;School of Energy and Power Engineering//Nanjing University of Science and Technology,Nanjing,Jiangsu 210094,China)

机构地区：[1]深地工程智能建造与健康运维全国重点实验室·中国矿业大学 [2]中国科学院武汉岩土力学研究所 [3]海洋能源利用与节能教育部重点实验室·大连理工大学 [4]南京理工大学能源与动力工程学院

出　　处：《天然气工业》2024年第7期186-198,共13页Natural Gas Industry

基　　金：国家自然科学基金项目“南海天然气水合物水平井分层开采过程中地层变形规律研究”(编号:42106210);“降压开采条件下南海典型水合物储层蠕变行为的多尺度表征与本构模型研究”(编号:42206225)。

摘　　要：现有研究结果表明,研究含天然气水合物(以下简称水合物)泥质粉砂沉积物电阻率特性对于安全、高效开发水合物藏具有重要意义,但目前关于细粒沉积物中颗粒排挤型水合物影响的研究较少,尤其是对沉积物固结收缩、受力变形和剪切破坏过程中储层电阻率的变化规律认识尚不充分。为此,采用3种制样方法制备了含不同饱和度水合物泥质粉砂沉积物,探究了沉积物在降温、水合物生成、N2气体驱替、水饱和、三轴固结和剪切破坏各阶段中电阻率的变化规律,并对固结和剪切阶段中电阻率的各因素敏感性进行了分析。研究结果表明:①水合物生成会急剧增大沉积物电阻率至1 kΩ·m以上,含20%和40%饱和度水合物沉积物电阻率差值超过350Ω·m,而水饱和过程则促使电阻率减小至40Ω·m以下;②有效围压由1.0 MPa增大到1.5 MPa时,饱和气状态下含20%饱和度水合物沉积物电阻率最大可降低253Ω·m,而饱和水状态下降幅约为2Ω·m;③沉积物导电能力受孔隙介质相态变化影响显著,主要机制为水合物生成堵塞导电通道,水饱和强化电流传导,而水合物胶结能力下降和孔隙气残余则会弱化电流传导。结论认为,孔隙介质和外部压力是影响泥质粉砂沉积物电阻率变化的两大重要因素,后续研究中应加强这些因素进行耦合分析,以期为海洋水合物开采过程中储层扰动风险预测提供理论支持。The existing research results indicate that the studies on the electrical resistivity properties of natural gas hydrate(hereinafter referred to as hydrate)bearing clayey-silty sediments are of great significance for the safe and efficient development of hydrate reservoirs.At present,however,the influences of particle squeeze type hydrates in fine grained sediments are less researched,and particularly the change laws of reservoir resistivity in the processes of sediment consolidation shrinkage,force deformation and shear failure have not been understood sufficiently.In this paper,hydrate bearing clayey-silty sediments with different hydrate saturations are prepared using three sample preparation methods,the change laws of sediment resistivity in the stages of cooling,hydrate formation,N2 gas displacement,water saturation,triaxial consolidation,and shear failure are investigated,and the sensitivity of different electrical resistivity factors in consolidation and shear stages are analyzed.And the following research results are obtained.First,the formation of hydrate can lead to the sharp increase of the sediment resistivity to above 1 kΩ·m,and the difference in the electrical resistivity of hydrate-bearing sediments with 20%and 40%hydrate saturation exceeds 350Ω·m,while the process of water saturation promotes the electrical resistivity to decrease below 40Ω·m.Second,when the effective confining pressure increses from 1.0 MPa to 1.5 MPa,the maximum electrical resistivity of the hydrate-bearing sediments with 20%hydrate saturation can decrease by 253Ω·m under the gassaturated state,and approximately 2Ω·m under the water-saturated state.Third,sediment conductivity is significantly affected by the phase state change of porous media,whose primary mechanisms include hydrate blocking conductive pathways and water saturation enhancing current conduction,while decreased hydrate cementation capacity and residual pore gas weakening current conduction.In conclusion,porous medium and external pressure are two major fa

关 键 词：天然气水合物 泥质粉砂沉积物 电阻率 孔隙介质 水合物饱和度 有效围压 水合物分解与再生成 

分 类 号：TE122.2[石油与天然气工程—油气勘探]