海拉尔盆地贝尔凹陷的油气运聚分析

海拉尔盆地贝尔凹陷是一个以白垩系沉积为主的陆相断陷区。采用条件分析法,对贝尔凹陷的油气运聚条件及其成藏的基本模式进行了系统研究,认为,贝尔凹陷在剖面上有3套成藏组合,其中中部成藏组合最佳;在平面上可分为5个运聚系统,其中以位于凹陷西北部的3个系统为最佳。该凹陷不同构造部位的运聚条件相差较大,生烃洼陷深部位的油气运移以砂岩储集层和断裂为主要输导通道,构造高部位的油气运移以断裂为主,而两者之间的油气输导则以不整合面和断裂为主。在油气运聚和成藏模式分析的基础上,认为贝尔凹陷油气运聚的有利条件主要包括生油凹陷有充足的油源、生油区内有继承性发育的圈闭构造以及各运聚要素间存在良好的时空配置关系3个方面。

OIL MIGRATION AND ACCUMULATION IN THE BEIER DEPRESSION,THE HAILAER BASIN

The Beier depression, which is located in the Hailaer basin, is a Cretaceous faulted depression with terrestrial sediments. Because the studies on oil migration and accumulation of the depression are relatively weak, this paper analyzes the migration conditions and accumulation models of the depression by using system idea. There are 3 accumulation systems from vertical sections in the Beier depression, among which the best one is the middle.While the depression is divided into 5 migration and accumulation systems on horizontal plane, among which the best ones are located in the northwest part of the depression. Since the migration conditions of the depression vary distinguishingly, the accumulation conditions and effects transform promptly in different structural unites. The oil in the deeper part of the Beier depression takes the sandstones and faults as the dominant pathways, while the oil in the upper part of the depression chooses mainly the faults as their pathways. Accordingly, the oil between the generation kitchens and traps of the depression selects the faults and discordances as the pathways.Based on migration and accumulation analysis, the paper deems that the favorable areas for oil to accumulate within the Beier depression are determined mainly by 3 conditions as followings:sufficient oil supplying,inherited traps and space time matches of the migration and accumulation factors.