鄂西渝东区油气保存条件分析

HYDROCARBON PRESERVATION CONDITIONS IN WEST HUBEI AND EAST CHONGQING

通过对鄂西渝东区盖层展布及封盖性能、主要断层封闭性和钻井地层水化学环境等的分析认为,该区保存条件存在差异性。石柱复向斜主体因盖层完整、特别是下三叠统嘉陵江组膏盐岩盖层连片分布且断裂构造不发育而保存条件最好;方斗山、齐岳山潜伏构造保存条件较好,但位于西侧的方斗山潜伏构造要好于齐岳山潜伏构造;复背斜主体因区域大断层的开启及区域盖层的剥蚀而保存条件较差;利川复向斜南部盖层较完整,保存条件较好,而北部较差。

Analyses of distribution and preservation characters of sealing rocks, sealing ability of main faults and chemical environment of formation water in wells have indicated that, there are differences of hydrocarbon preservation conditions among different regions in West Hubei and East Chongqing. Due to occurrence of complete sealing sequence, especially wide distribution of gypsum seal of the Lower Triassic Jialingjiang Formation and poor development of fault structures, the Shizhu synclinorium is most favorable for hydrocarbon preservation. The Fangdoushan and Qiyueshan buried structures are both favorable for preservation, with the former better than the latter. Main part of synclinorium shows poor preservation conditions as the result of regional large fault opening and regional seal erosion. In the south of Lichuan synclinorium, seals are relatively complete and preservation conditions are good; while in the north, it is poor.