天然气水合物三维成藏物模实验系统的构建与检验  

A large-scale three-dimensional device for simulating natural gas hydrates accumulation and distribution process in sediments

作　　者：粟科华[1,2] 孙长宇[2] 李楠[2] 钟小禹 陈光进[2] 

机构地区：[1]中国石化石油勘探开发研究院 [2]中国石油大学(北京)重质油国家重点实验室

出　　处：《天然气工业》2013年第12期173-178,共6页Natural Gas Industry

基　　金：中国博士后科学基金"亚/跨音速天然气水合物形成演化机理"(编号:2013M530849);国家自然科学基金杰出青年基金"天然气水合物"(编号:20925623);国家自然科学基金"复杂多孔介质体系水合物热力学生成条件/生成量及预测模型研究"(编号:21076225)

摘　　要：现有的天然气水合物(以下简称水合物)成藏模拟装置侧重于合成少量均相水合物或含水合物沉积层,受制于装置体积,而某些影响因素如地温梯度等难以在室内实验中再现。为此,提出了建立水合物成藏大型三维物模实验系统来解决相关问题的技术思路。首先通过调研分析,确定了系统的设计指标:最大工作压力为32MPa,模拟地温梯度介于3～6K/100m,可再现自然界扩散、渗漏、原位3种水合物成藏机理。据此建立了物模实验系统:①系统主体高压反应釜容积为196L,内置30个PT100温度传感器、30个电阻率探测电极、16对声偶极子,构成覆盖整个沉积层的传感器点阵;②系统可在海底和陆地水合物成藏典型温压条件下模拟多种天然气供气方式,考察水合物的动态生成行为,以及成藏后新鲜海水循环下的水合物动态演化行为。试运行结果表明:该系统满足设计指标中提出的各项要求,实验流程可确保安全、稳定、长期运行;传感器经过标定后,可以准确测定各个物理量。最后,通过测定实验介质的多项物性参数值,进一步验证了该系统的可行性和可靠性。The current device for simulating the formation of a natural gas hydrate reservoir only focuses on composing a small amount of homogeneous hydrates or hydrate-bearing sediments; so restricted by the device volume, such influencing factors as geothermal gradient are too difficult to present in the simulation process. In view of this, a novel large-scale three-dimensional natural gas hydrate physical simulation device, with a capacity of 196 L and the maximum operation pressure of 32 MPa, was designed and developed to study the hydrate accumula- tion and the methane recovery from hydrate-bearing sediments in a natural environment. Acoustic, electrical, and thermal properties at differ- ent positions can be collected in real time to analyze the evolution of hydrate-bearing porous media during the accumulation of hydrate or the production of natural gas.The formation system of this device contained a high-pressure vessel, the inner space of which was divided into three parts by two porous stainless steel plates and the porous medium to simulate the hydrate stability zone in natural environment and sensors were placed in the space between the two plates. For the sensors system of this device, 30 resistance temperature detectors, 30 electrical re- sistance electrodes, and 16 acoustic dipoles were inserted into the porous medium to detect the variation of physical properties due to hydrate formation or dissociation. A heating coil was mounted on the bottom lid of the reactor and hot water circulates in the heating coil driven by a pump to simulate the actual geothermal gradient （3 - 6 K/100m） in sediments, reappearing the formation mechanisms of the in-situ hydrates, hydrate transport by diffusion or seepage in sediments. Initial experiments showed that this device can be used to produce large a- mounts of hydrate-bearing sediments under a wide range of experimental conditions.

关 键 词：天然气水合物 成藏 三维物模实验系统 地温梯度 电阻率 声速 孔隙介质 高压反应釜 

分 类 号：P744.4[天文地球—海洋科学]