金湖凹陷墩塘-小关地区戴一段岩性油藏成藏规律

Lithologic reservoir-forming rules of first Member of Dainan Formation in Duntang-Xiaoguan area, Jinhu Sag

随着油气勘探开发的不断深入,岩性油藏成为近年来金湖凹陷滚动勘探的重点目标。文中针对金湖凹陷龙岗次凹地区戴一段(E2d1)岩性油藏成藏规律及主控因素,开展了沉积相、储层特征、成藏规律及重点油藏解剖等相关研究。通过岩心观察、化验资料分析等研究,认为龙岗次凹地区E2d1主要发育扇三角洲相、湖相滨浅湖亚相及三角洲相。根据砂体厚度变化、储层地震预测等成果,认为墩2断块E2d12岩性油藏为砂岩上倾尖灭油藏,并提出研究区岩性油藏主要发育于E2d1中下部,成藏条件苛刻。E2d1中下部部分地区发育以泥岩为主、夹薄层砂岩的滨浅湖亚相和沟通阜宁组油源的断层,是岩性油藏成藏的主要控制因素。

With the exploration and development of oil and gas, the research of the lithologic reservoir has become an important part of rolling exploration in Jinhu Sag in recent years. In this paper, the sedimentary facies, reservoir characteristics, reservoir-forming rules and the anatomy of the key reservoirs are researched to analyze the lithologic reservoir-forming rules and factors of the first Member of Dainan Formation in Duntang-Xiaoguan area, Jinhu Sag. On the basis of core observation and analysis of test data, it is considered that fan-delta facies, shore-shallow lake subfacies and delta facies are mainly developed in the first Member of Dainan Formation. Utilized the characteristics of sand thickness and the results of seismic reservoir prediction, the reservoir type of the Dun 2 Fault Block E2d12 is considered to be lithology upward dip pinch out reservoir, the lithologic reservoirs are mainly developed in the middle and lower part of the first Member of Dainan Formation, and the reservoir forming conditions is complicated. There are two main control factors of the lithologic reservoir-forming in the work area, the first one is the mudstone-dominated strata with thin sandstone beds which have been formed in shore-shallow lake subfacies in the middle and lower parts of the first Member of Dainan Formation, and the second is the faults that communicate oil sources in Funing Formation.