高压环境下流体非饱和渗流对含水合物沉积物的影响  

Influences of unsaturated fluids on hydrate-bearing sediments under high-pressure seepage environment

作　　者：关进安[1] 梁德青[1] 吴能友[1] 万丽华[1] 李栋梁[1] 苏正[1] 

机构地区：[1]中国科学院广州能源研究所中国科学院可再生能源与天然气水合物重点实验室,广州510640

出　　处：《岩土力学》2013年第3期639-644,652,共7页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.50904056);NSFC-广东省联合基金(No.U0933004);中国科学院重点部署项目(No.KGZD-EW-301);国家海洋地质专项(No.GHZ2012006003)

摘　　要：沉积物与流体流动的性质是影响水合物形成和聚集的两个重要因素,为研究水合物在沉积地层中的赋存机制必须探明高压环境下含水合物沉积物在非饱和渗流条件下的相互影响关系。以逸度差为水合物反应驱动力,反应动力学常数为Arrhenius类型,建立了包括非饱和流体流动-沉积物特征-水合物形成动力学耦合的二维模型,从理论上研究了多孔介质内流体与沉积物参数如含水率、去饱和系数、水力分布和水合物饱和度等在孔隙内的相互影响规律。结果表明,在设定的条件下,随着反应的进行孔隙水压力随时间逐渐大,在相同条件下水合物饱和度与温度增加导致孔隙水压力变大,其中水合物饱和度的影响较小,而沉积物基质吸力、去饱和系数与本征动力学常数则与孔隙水压力成反向变化,其中本征动力学常数的影响较大。Sediments and fluids characteristics are the two important factors affected the formation and accumulation of methane hydrate in deposits. In order to study methane hydrate occurrence in sediments, the influences of unsaturated fluids on hydrate-bearing sedimentary strata under high-pressure seepage environment must be discussed. The difference of fugacity has been adopted to be the driving force in this reaction. The hydrate intrinsic kinetic constant has been written in an Arrhenius-type equation. A two-dimensional （horizontal, vertical） model coupling the aspects of unsaturated flow fluids-sedimentary characteristics-hydrate formation kinetics has been established. The evolution of porous hydraulic parameters such as water content, to-saturation coefficient, pore water pressure and hydrate saturation have been discussed. Under the conditions setting in the simulation, the results show that the pore water pressure becomes larger with time during the reaction proceeding. Under the same conditions, the increase of strata temperature and hydrate saturation will increase the pore water pressure. The hydrate saturation causes less influence; while the sediments matric suction, to-saturation coefficient and hydrate intrinsic kinetic constant will vary inversely with the pore water pressure; and the to-saturation coefficient has more strong effects.

关 键 词：含水合物沉积物 形成动力学 水合物含量 孔隙水压力 水力参数 

分 类 号：TE122.2[石油与天然气工程—油气勘探]