深层页岩纳米孔隙中气水微观动用机理  

Microscopic mobilization mechanism of gas and water in deep shale nanopores

作　　者：黄亮[1,2] 杨琴[1,2] 吴建发 杨学锋 冯鑫霓 张鉴 赵圣贤 黄山 周文 HUANG Liang;YANG Qin;WU Jianfa;YANG Xuefeng;FENG Xinni;ZHANG Jian;ZHAO Shengxian;HUANG Shan;ZHOU Wen(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation//Chengdu University of Technology,Chengdu,Sichuan 610059,China;College of Energy,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Shale Gas Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China)

机构地区：[1]油气藏地质及开发工程全国重点实验室•成都理工大学 [2]成都理工大学能源学院 [3]中国石油西南油气田公司页岩气研究院

出　　处：《天然气工业》2024年第1期139-148,共10页Natural Gas Industry

基　　金：国家自然科学基金资助项目“川南龙马溪组页岩干酪根中气水赋存特征与孔隙变形机理”(编号:52204031);四川省自然科学基金资助项目“深层页岩变形孔隙中水—CH_(4)—CO_(2)微观赋存及动用规律”(编号:2023NSFSC0947)。

摘　　要：深层页岩气已成为我国天然气产量增长最现实的领域之一。已有研究结果证实深层页岩纳米孔隙发育,但页岩储层在高温高压含水条件下气水的动用复杂程度加剧。传统页岩岩心尺度的解吸和驱替实验成本高、周期长,难以解析纳米孔隙中气水在深层储层条件下的微观动用机理。为此,基于分子模拟方法,在考虑气水质量扩散传递的基础上,提出了1套页岩气水动用模拟方法,并模拟了深层页岩双重介质复合纳米孔隙中的甲烷和水分在2种不同模式下的动用机理,并量化了甲烷吸附气、溶解气和自由气,揭示了孔隙水和甲烷不同赋存状态的微观动用机理。研究结果表明:①页岩中伊利石对甲烷的亲和性强于干酪根,伊利石亲水性远大于干酪根;②2种动用模式下,伊利石中赋存的水分基本不发生动用,干酪根表面水分团簇可发生动用;③双重介质复合纳米孔隙中,甲烷的自由气动用率最大,溶解气和吸附气动用率较低,是后期页岩气储量挖潜的重要潜在资源。结论认为,深层页岩纳米孔隙中气水的微观动用理论研究对深层页岩气可采储量评估、产能评价和提高采收率等方面具有重要理论意义。Deep shale gas has become one of the most practical fields for natural gas production increase in China.Existing research results have proved that deep shale possesses abundant nanopores,but high temperature,high pressure and water bearing aggravate the complexity of gas and water mobilization in shale reservoirs.The traditional desorption and displacement experiment of shale core scale is costly and time-consuming,and can hardly reveal the microscopic mobilization mechanism of gas and water in nanopores under the conditions of deep reservoirs.Based on the molecular simulation method,this paper proposes a shale gas-water mobilization simulation method considering gas and water mass diffusion and transfer.Then,the mobilization mechanisms of methane and water in the dual-medium nanopores of deep shale under two different modes are simulated.Finally,the adsorbed,dissolved,and free methane are quantified,and the microscopic mobilization mechanisms of pore water and methane in different occurrence states are revealed.And the following research results are obtained.First,illite in shale has a greater affinity for methane than kerogen,and illite is much more hydrophilic than kerogen.Second,under the two mobilization modes,water in the illite is basically immovable while the water clusters on the kerogen surfaces are movable.Third,in the dual-medium nanopores,free methane has the highest mobilization rate,while dissolved methane and adsorbed methane have a lower mobilization rate,so they are the important potential resources for shale gas reserves increase in the late stage.In conclusion,the theoretical research on the microscopic mobilization of gas and water in deep shale nanopores is of great theoretical significance to the recoverable reserves estimation,production capacity evaluation and recovery factor improvement of deep shale gas reservoirs.

关 键 词：深层 页岩气 纳米孔隙 解吸 水分 赋存状态 可动性 

分 类 号：TE37[石油与天然气工程—油气田开发工程]