冀东南堡凹陷关键成藏时刻主要断裂封闭性分析

Analysis of the closeness of the main faults in Nanpu Sag in southeastern Hebei at key hydrocarbon accumulation moments

近年来对含油气系统的研究表明,控制油气成藏的因素很多,其中断层的封闭性与油气成藏具有密切的关系.本文在对控制断裂封闭性因素进行分析的基础上,认为断面正压力和泥岩涂抹系数是定量评价断裂封闭性的两个主要参数,并对断面正压力的计算方法进行了改进,综合考虑了水平最小主应力的作用效果.运用这种方法对南堡凹陷的主要断裂在两个关键成藏时刻的封闭性进行了讨论,表明断层的封闭性与埋深和区域应力等综合因素具有密切关系;主要断裂垂向上总体下部开启、上部封闭,且Nm期封闭性较强;侧向上基本上保持封闭,且Ed期封闭性较强;指出断裂构造复杂地区以浅部勘探为主,断裂相对简单地区以深部勘探为主,且集中在Ng组和Ed2以下层位.

The recent researches on hydrocarbon accumulation show that there are many factors affecting hydrocarbon accumulation, and among them, the closeness of faults has close relation with hydrocarbon accumulation. It is held that the normal force of fault surface and the daubing coefficient of mudstone are two main parameters for quantitatively evaluating the closeness of faults based on the analysis of all the factors controlling the closeness of faults. And the method for calculating the normal force of fault surface is modified on the basis of comprehensively considering the effect of horizontal minimum major stress. In addition, the closeness of the main faults at two key hydrocarbon accumulation moments of the sag is discussed. And it is show that the closeness of the main faults has close relation with the comprehensive factors including their buried depths, regional stress, etc. The main faults are open down and close up in vertical direction, and the closeness is better in Nm period. They are basically close laterally, and the closeness is better in Nd period. It is pointed out that shallow exploration should be given first place in complicated fault structure area and deep exploration should be given first place in simple fault structure area, and the exploration should mainly focus on Ng and Ed2.