中国中西部砂岩天然气大规模聚集机制与成藏效应  

Large-scale gas accumulation mechanisms and reservoir-forming geological effects in sandstones of Central and Western China

作　　者：李伟[1] 王雪柯 张本健 陈竹新[1] 裴森奇 于志超[1] LI Wei;WANG Xueke;ZHANG Benjian;CHEN Zhuxin;PEI Senqi;YU Zhichao(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;China Northwest Sichuan Gas Mine of Southwest Oil and Gas Field Company,PetroChina,Sichuan 621700,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油西南油气田公司川西北气矿,四川江油621700

出　　处：《石油勘探与开发》2020年第4期668-678,共11页Petroleum Exploration and Development

基　　金：国家科技重大专项“前陆冲断带及复杂构造区油气成藏、分布规律与有利区评价”(2016ZX05003-002);中国石油天然气股份有限公司科研项目“四川盆地天然气资源潜力分析及新区新领域勘探目标评价”(2016E-0601)。

摘　　要：中国中西部大型含油气盆地中天然气大规模富集区具有多种特殊的聚集机制与不同的成藏效应。以天然气成藏地质理论与方法为基础,开展了典型含油气盆地区域地质与构造背景、地层埋藏演化、气藏基本特征、流体地质与地球化学等方面的研究。结果认为,喜马拉雅期以来隆升剥蚀所产生的构造抽吸、泥岩吸水、水溶气脱溶、流体封存等地质作用都能形成大规模的天然气聚集,并能形成不同的天然气成藏地质效应。如:大面积的构造抽吸作用与流体封存作用有利于区域性超高压流体的赋存及大规模超高压气田的形成;低砂地比地层中产生的泥岩吸水作用有利于区域性低压、无水气藏等大气区的发育;大面积厚层砂岩中水溶气的脱溶作用不仅能形成大规模的天然气聚集,而且地层水侧向运移产生的水溶气脱溶,会产生区域性有规律的天然气同位素分馏效应,即天然气水溶气运移距离越远,所聚集形成的天然气甲烷碳同位素组成越重。Large-scale gas accumulation areas in large oil-gas basins in central and Western China have multiple special accumulation mechanisms and different accumulation effects.Based on the geological theory and method of natural gas reservoir formation,this study examined the regional geological and structural background,formation burial evolution,basic characteristics of gas reservoirs,and fluid geology and geochemistry of typical petroliferous basins.The results show that the geological processes such as structural suction effect,mudstone water absorption effect,water-soluble gas degasification and fluid sequestration caused by uplift and denudation since Himalayan stage all can form large-scale gas accumulation and different geological effects of gas accumulation.For example,the large-scale structural pumping effect and fluid sequestration effect are conducive to the occurrence of regional ultra-high pressure fluid and the formation of large-scale ultra-high pressure gas field;mudstone water absorption effect in the formation with low thickness ratio of sandstone to formation is conducive to the development of regional low-pressure and water free gas reservoir;the exsolution effect of water-soluble gas in largescale thick sandstone can not only form large-scale natural gas accumulation;moreover,the degasification of water-soluble gas produced by the lateral migration of formation water will produce regional and regular isotopic fractionation effect of natural gas,that is,the farther the migration distance of water-soluble gas is,the heavier the carbon isotopic composition of methane formed by the accumulation.

关 键 词：中国中西部盆地 天然气大规模聚集机制 构造抽吸作用 泥岩吸水作用 水溶气脱溶作用 流体封存作用 天然气成藏 

分 类 号：TE122[石油与天然气工程—油气勘探]