桑植-石门复向斜油气有利区带预测

The forecast for the favorable reserve zones of oil and gas in Sangzhi-Shimen synclinore

桑植-石门复向斜具有很好的油气显示,但是总体勘探程度较低。为明确研究区的下一步勘探重点,本文综合野外地面地质调查、野外岩石样品生储盖能力的分析和MT资料综合解释等几方面结果对研究区的石油地质特征、构造与油气的关系和具体构造圈闭情况进行了较为详细的研究。研究结果表明研究区主要发育下震旦统陡山沱组、寒武系黔东统牛蹄塘组、晚奥陶世五峰组-早志留世龙马溪组等3套烃源岩,上震旦统灯影组、寒武系黔东统清虚洞组和武陵统孔王溪组等三套较好的储集层,寒武系黔东统和下志留统等两套区域盖层;加里东-印支期为岩性油藏形成阶段,晚印支-早燕山期为气藏形成阶段,晚燕山-喜山期以气藏调整、改造、再分配甚至破坏作用为主。最终发现四望山背斜、天子山背斜等2个局部构造为桑植石门复背斜下一步的重点勘探目标。

The exploration degree is still relatively low although there are abundant oil and gas signs shows in Sangzhi-Shimen synclinore. In order to determine the key exploration targets in the future, that a detailed study of petroleum geological characteristics, the relationship between structure and petroleum, and the structural traps of the research area are carried on by the methods of the field geological survey, sample analysis of source-reservoir-cap assemblage, and integrated interpretation of MT data in this paper. The result reveals that three sets of hydrocarbon source rock series, i.e., the Doushantuo Formation of Lower Sinian, the Niutitang Formation of Qiandong Series of Cambrian, the Wufeng Formation of Late Ordovician and Longmaxi Formation of Early Silurian;three sets of reservoir rock series, i.e., the Dengying Formation of Upper Sinian, the Qingxidong Formation and Kongwangxi Formation of Cambrian; and two sets of regional cap rock series of Qiandong Series of Cambrian and Lower Silurian, are developed in the research area. The lithologic reservoirs were formed during the stage of Caledonian and Indosinian, while the gas reservoirs were formed during Late Indosinian and Early Yanshanian. The reservoirs were reworked, redistributed and destructed during Late Yanshanian and Himalayan period. It is concluded that the Siwangshan anticline and the Tianzishan anticline can be served as the favorable targets for the further exploration in Sangzhi-Shimen synclinore.