东濮凹陷北部流体作用与油气运聚

Fluid action and hydrocarbon migration and accumulation in the northern part of Dongpu Sag

东濮凹陷北部断裂破碎,盐岩发育,油气运聚过程及油、气、水分布关系复杂。文中通过分析东濮凹陷北部古近系现今流体在平面和剖面上的分布特征,结合研究区地质背景及分析测试资料,研究了东濮凹陷北部古近系流体作用与油气富集、分布、成藏之间的关系。东濮凹陷北部地层水矿化度高值区主要分布在中央隆起带的文留地区,沙河街组各层段高矿化度地层水分布范围基本吻合,表明该地区断裂发育,地层垂向连通性具有一定的继承性。地层水矿化度高值区与油气富集区在平面分布上具有高度的一致性。总体上,东濮凹陷北部地层水以原生沉积水为主,是强烈水岩作用的结果,受大气降水影响作用相对较弱,地层封闭条件较好。东濮凹陷北部沙三段除西部斜坡带及卫城-文明寨地区为弱低压—常压外,其余地区普遍发育高压。超高压主要分布在文留东部及中部,超高压分布区也是油气最为富集的区域。文留地区油气以垂向运移为主、侧向运移为辅,油气大量运移充注及盐岩良好的封盖性,对文留地区高压的保存起着极其重要的作用。

Broken faults and widely developed salts are featured in the northern part of Dongpu Sag.And hydrocarbon migration and accumulation processes and the contacts between water,oil and gas is complex.Based on analysis of the current horizontal and vertical distribution characteristics of the Paleogene formation water,and combing with the geological background of the study area and the analysis and test data,the relationship between the fluid action and the accumulation and distribution of hydrocarbon in northern Dongpu Sag are deeply studied.The high concentration salinity of formation water in the northern part of Dongpu Sag is mainly distributed in the central uplift zone of Wenliu area,and the distribution range of high salinity of formation water in each member of the Shahejie formation is basically consistent,indicating that faults are developed in this area and the vertical connectivity of strata is good.The high salinity area of formation water has good consistency in plane distribution with the oil and gas accumulation area.In general,the formation water of the Shahejie formation is dominated by syngenetic sedimentary formation water,which is the result of strong water-rock reaction.The effect of atmospheric water is relatively weak and the formation sealing condition is good.Except the western slope belt and the Weicheng-Wenmingzhai area have weak low pressure and normal pressure,high pressure is generally developed in the Es_(3) formation of the northern part of Dongpu Sag.The ultrahigh pressure is mainly distributed in eastern and central Wenliu area.Ultrahigh pressure area is also most abundant area for oil and gas.In Wenliu area,the fluid mainly migrated vertically,supplemented by lateral migration.Large vertical migration of hydrocarbon and good sealing of salt rocks play an extremely important role in the preservation of high pressure in Wenliu area.