断层输导作用与油气充注作用关系分析

The analysis of differences between fault conduiting and charging for hydrocarbon

断层是控制油气藏形成的重要因素之一,断层的开启及闭合影响到油气运移与聚集的效率。但油气在断层中的运移与在砂层中的充注存在差异性这一问题长期被忽视。一般认为,只要发育断层,其断开的渗透层就会被油气充注,极少关注地层水和石油的压缩特性对充注的影响。本文提出,地下单断层活动时,深部油气在超压作用下以涌流方式难以快速充注进入中浅层被切割的砂体,因此,单砂体至少要存在一条断层作为泄水出口,石油才能通过其余断层充注进入砂体,即单砂体要发育两条及两条以上断层,石油才能注入砂体。在断层静止期,油气通过渗流方式沿特定深度范围断面垂向运移,对油气垂向运移距离影响较小。本文运用4个大型盆地的典型油气藏与断层分布关系讨论了本文观点。该观点对油气成藏规律研究及成藏目标评价有较重要参考意义。

The fault＇s opening and closing have an influence on the efficiency of hydrocarbon migration and accumulation so it is one of the main factors to control reservoir formation.There is a long neglected question that the hydrocarbon migration and charge in fault is different.It is generally acknowledged that as long as the permeable layer is broken by faults,the layer can be charged by over pressure hydrocarbon.The influence of formation water and hydrocarbon compression property to the charging is rarely witnessed.The paper presented that when single fault activating,under the overpressure,it is hard for deep hydrocarbon to charge the shallow reservoir bed in a form of flashy flow.To a single sand body,a fault acting as the spillway should exist so that the hydrocarbon can successfully charge the sand body through other faults.Therefore,there must be two or more faults,the sand body can be charged.At fault resting stage,hydrocarbon migrates up through the fault surface by the way of seepage that has little influence on the vertical distance the hydrocarbon can reach.This paper discussed the viewpoint by using the relation between typical reservoirs and fault distrubution in four largescale basins.This view is meaningful to the study of hydrocarbon distribution and the evaluation of hydrocarbon accumulation target.