车镇凹陷西部沙二段油气成藏条件及勘探方向分析

Analysis of oil-accumulation condition and exploration direction of the second member of Shahejie Formation in the western Chezhen Sag

以构造和沉积为背景,从烃源岩、储层、盖层、油气运移通道等方面出发,对车镇凹陷西部沙二段的成藏条件和勘探方向进行了分析。结果表明,沙二段具有较好的油气成藏条件,其油气主要来源于沙三中下亚段的烃源岩;储层在全区广泛分布,其中Es2"4"旋回是有效储层发育层段;发育有多种类型的盖层,盖层的封闭条件较好,有利于油气的保存;三种运移通道,即断层、不整合面和砂体,在油气成藏过程中起着举足轻重的作用。沙二段已发现构造-岩性、构造两种类型的油藏,也可能存在地层超覆油藏。尽管目前沙二段的勘探研究工作存在很大困难,但仍具有较大的勘探潜力,曹家庄断阶带和南坡超覆带是寻找构造-岩性油藏和地层超覆油藏的有利区带,也是下一步的主要勘探方向。

Based on the tectonic and sedimentary characteristics,oil-accumulation condition and exploration direction of the second member of Shahejie Formation in the western Chezhen Sag are analyzed by means of the study on hydrocarbon source rocks, reservoirs, caprocks and hydrocarbon migration pathways. The results show that the second member of Shahejie Formation has a good condition for forming hydrocarbon reservoirs:The oil and gas mainly come from the hydrocarbon source rocks in the middle-lower submember of Es3; The reservoirs were developed in the study area and the fourth cycle is very important one; There are many kinds of caprocks with good sealing capacity which are in favor of protecting hydrocarbons; There are three types of hydrocarbon migration pathways, such as faults, unconformity surfaces, sand bodies, which are very important to the processof forming oil and gas reservoirs. Up to now, the tectoniclithologic reservoirs and tectonic reservoirs have been foundin the second member of Shahejie Formation, stratigraphic o-verlapped reservoirs may be in existence. Though it is difficult to make research on the second member of Shahejie Formation, it still has a good exploration potential, for example, the Cao Jiahzhuang fault step zone and overlapped zoneon the southern slope are more favorable areas for next ex-ploration in search of tectonic- lithologic reservoirs and stratigraphic overlapped reservoirs.