下扬子句容地区海相上组合油气地质条件评价

Evaluation on oil and gas geological conditions of upper marine formation assemblage in Jurong area of lower Yangtze area

下扬子句容地区的构造形成演化可以分为海相盆地稳定隆降、逆冲推覆、拉张断陷3个阶段。受盆地形成演化的控制,句容地区海相上组合烃源岩主要为盆地构造稳定阶段沉积的二叠系泥岩及下三叠统青龙群泥岩、碳酸盐岩;储层主要为侏罗系象山组、二叠系龙潭组砂岩储集层和三叠系青龙群碳酸盐岩储集层;区域性盖层为白垩系浦口组泥岩。虽然该区海相地层遭受了多期次不同方式、不同程度的改造作用,对油气成藏条件产生了很大影响和破坏,但研究认为在后期改造相对薄弱地区如该区后缘凹陷,仍具有良好的勘探前景,评价出索墅镇—黄梅桥—陈武地区和句容—行香地区2个有利区块。

The tectonic formation and evolution in the Jurong area of lower Yangtze area could be divided into three stages of stable uplift and deposition,the extrusion and nappe,the extension and rift for marine basins. Controlled by evolution of the basins,the main source rocks were Permian mudstones and the lower Triassic limestone and mudstones deposited in stable sedimentary stage; the primary reservoirs were Jurassic Xianshan Formation and Permian Longtan Formation sandstones and Triassic Qinglong Group limestone; the regional seal was Cretaceous Pukou mudstone. Although the marine formations in the area suffered many times tectonic modification of different ways and degrees,which had a great impact on hydrocarbon accumulation,the research showed that the districts with weak tectonic modification still had a good exploration prospect,such as post marginal depression. Therefore,two favorable oil-bearing blocks were evaluated in the study area,they were Sushu Town-Huangmeiqiao-Chenwu block and Jurong-Xinxiang block.