统计地层实测压力数据,研究渤海湾盆地车镇凹陷始新统地层流体异常压力分布特征.结果表明：始新统沙河街组三段和沙四段地层流体发育异常高压,超压压力因数在1.20~1.78之间;平面上超压主要发育在凹陷中央部位;纵向上现今地层深度2 100m以上基本为常压,深度2 100m以下出现明显压力异常,主要分布于沙三段和沙四段地层.单井泥岩测井曲线特征显示,烃源岩生烃演化模拟和包裹体PVT模拟恢复最小,在超压层段声波时差偏离正常趋势线,表现为较高的声波时差值,密度测井曲线符合正常的压实规律;在两期油气充注时期,烃源岩热演化生成大量烃类流体,并以第二期生排烃活动为主,与地层流体超压阶段符合;第一期包裹体在常压环境捕获,第二期包裹体主要在超压环境捕获.始新统沙三段和沙四段地层流体超压主要由生烃作用引起.
Through statistically measured formation pressure data in chezhen sag of Bohai bay basin,we made a research into the characteristics of abnormal formation pressure.The results show that abnormal high pressure develops in the 3rd and 4th member of Shahejie formation.The coefficient of pressure ranges from 1.20 to 1.78.Overpressure is mainly distributed in the center of the sub-sag area.The depth of top seal appears under 2 100 m,mainly distributes in the 3rd and 4th member of Shahejie formation.By logging curve characteristics of mudstone,hydrocarbon source rock evolution simulation,inclusion homogenization temperature measurement and PVT simulations restore the minimum captured pressure show that:Appears some regularity in overpressure zone,acoustic time significantly deviates from the normal compaction trend,with high acoustic time value,the density conforms to the normal compaction regularity.In the two stages of oil and gas filling period,hydrocarbon source rock generate a large amount of hydrocarbon fluid,with the second stage is the mainly hydrocarbon generation and expulsion period,conform to the formation fluid overpressure stage.The first stage of the inclusions are captured in normal pressure environment,the second stage of the inclusions are captured mainly under overpressure environment.Comprehensive analysis of the 3rd and 4th member of Shahejie formation fluid overpressure is mainly caused by hydrocarbon generation.
Journal of Northeast Petroleum University
well logging curve
Bohai bay basin