浅海断陷盆地天然气运聚成藏史研究:以渤海海域北部JZ20-A气田为例

Research on history of gas migration and accumulation of fault basin in shallow sea:Examples in JZ20-A Gas Field of northern offshore of Bohai Bay Basin

基于天然气的来源、运移通道、充注过程、充注期次和成藏史各要素的配置关系综合分析,结合天然气分析测试、地化分析和流体包裹体测试资料对JZ20-A气藏动态成藏过程进行研究。研究结果表明:JZ20-A气田天然气主要来源于辽中凹陷沙四—孔店段烃源岩,构造高部位是油气汇聚优势区域,该气藏天然气垂向运移距离约为3200m;长期持续活动的断层和不整合面构成的输导体系,将生成油气呈阶梯式运移至储层有利部位聚集成藏;研究区油气成藏期时间主要为12Ma至今,为一期持续充注。

Based on the comprehensive analysis of history of gas migration and accumulation including the origin, migration pathway,charging process,charging history of natural gas and the matching relations of the main factors for hydrocarbon accumulation,combined with natural gas analysis and testing and the test data of the geochemical,analysis of fluid inclusions,the JZ20-A gas reservoir dynamic accumulation process was studied.The results show that the natural gas of JZ20-A gas field mainly comes from the source rocks of the 4th member of Shahejie formation and Kongdian formation in Liaozhong Sag,structural high parts are the advantageous region of oil and gas aggregation,and the vertical migration distance of gas is about 3 200 m.The conduit system consisting of long-term sustainable active faults and unconformity leads oil and gas migrate into favorable parts in the manner of ladder stairs to accumulate.The hydrocarbon accumulation period in the study area is from 12 Ma to present,and belongs to a one-stage continuous filling.