鄂尔多斯盆地黑山墩地区断裂特征及与油气的关系

FAULT CHARACTERISTICS OF HEISHANDUN AREA OF THE ERDOS BASIN AND ITS CONTROL OF OIL AND GAS

鄂尔多斯盆地黑山墩地区存在上下2套构造系统,上下构造的分界线在T8反射层附近,其中上构造层是地区勘探目标层。上构造系统断裂依据其规模可以分为三级;一级、二级断裂主要为近南北向展布的逆断层,断至油源层以下;三级断裂主要为层间调谐正断层。断裂和局部构造主形成期为燕山早期,烃类排出期为燕山晚期,因此沟通油源并控制局部构造形成的一级、二级断裂对油气成藏起着积极的作用。结合钻后评估分析认为:鄂尔多斯盆地黑山墩地区成藏主控因素是构造,断层控制的断背斜是油气聚集的最有利场所;一、二级断裂在油气的初次分配中起着主要作用,三级层间断层在油气的再分配中起着重要作用。依据该认识,部署了nd17井,实钻获得15套油斑级以上油层。

There are two overlying structural systems in Heishandun working area of the Erdos Basin. They borders at around reflector T8 as show on seismic data. Among which the upper system is the target. It can be divided into three level fractures in terms of scale. The primary and second order fractures are mainly reverse faults extended down to the source rocks in south to north direction. The third order fractures are mostly intrabed normal faults. Faults and local structures were formed predominantly at early Yanshanian, and hydrocarbon expulsed at late Yanshanian. The primary and second order fractures, which connect oil sources and control local structures, play an active role in the accumulation of hydrocarbon. In combination with postdrill assessment, it is concluded that local structures are the controlling factor to the formation of hydrocarbon reservoir, and faulted anticlines are the favourable places for hydrocarbon accumulation. The primary and second order fractures play the main role in the initial allocation of hydrocarbon, whereas the third order intrabed fractures play an important role in the reallocation of hydrocarbon.