琼东南盆地深水区陵南低凸起古潜山油气成藏条件

    ACCUMULATION CONDITIONS OF BURIED-HILL HYDROCARBON RESERVOIRS ON THE LINGNAN LOW UPLIFT IN THE DEEP WATER AREAS OF QIONGDONGNAN BASIN

    • 摘要: 基于琼东南盆地深水区砂岩储层整体欠发育这一地质背景,综合评价了陵南低凸起古潜山领域油气成藏地质条件,并对该区的成藏模式与特征进行了预测和讨论。研究表明,陵南低凸起古潜山由邻近的乐东-陵水富生烃凹陷供烃,被成熟烃源岩包围,具有中生界花岗岩潜山储层与新近系厚层海相泥岩构成的储盖组合,发育大型沟源断裂及与之配置较好的大型继承性构造脊等构成畅通的运聚系统,具有源储压差大、近源直接充注的优势。相较已获勘探成功的松南低凸起古潜山油气藏,其成藏条件更为优越,成藏模式与越南白虎大型古潜山油田和渤海渤中19-6大型古潜山凝析气田具有一定的可类比性。陵南低凸起的石油地质条件切合琼东南盆地深水区“富泥贫砂”的地质背景,可形成大规模、连片性古潜山油气藏,是琼东南盆地中央峡谷水道领域之外又一有利的深水油气勘探新领域。

       

      Abstract: Buried hill reservoirs are quite common in the deep water areas of Qiongdongnan Basin, where sandstone reservoirs are rare. This paper is specially devoted to the forming conditions and geological models of buried-hill hydrocarbon reservoirs on the Lingnan Low Uplift. By careful correlation of the oil and gas exploration results and existing problems of the Songnan Low Uplift buried-hills in Northeast China, geological conditions for buried-hill oil and gas accumulations in the Qiongdongnan basin are comprehensively evaluated by means of the reservoir forming model and its characteristics. The study shows that the buried-hill on the Lingnan Low Uplift is surrounded by matured source rocks. Hydrocarbon is supplied by the Ledong-Lingshui hydrocarbon-rich sag next to it. There is a coupled reservoir cap assemblage composed of Mesozoic granite buried-hill reservoir and Neogene thick cover of marine mudstone. There also occurs a smooth migration and accumulation system composed of large source-connected faults and large inherited structural ridges. Large pressure difference occurs between the source and storage that ensure the reservoir directly to be charged by near source oil and gas. Compared with the buried-hill reservoir on the Songnan Low Uplift, which has been successfully explored, the reservoir forming conditions are excellent in the study area. It could be compared with the large Baihu buried-hill oilfield in Vietnam and the Bozhong 19-6 buried-hill condensate gas field in the Bohai Sea. The petroleum geological conditions of the Lingnan Low Uplift, which is "rich in mud and poor in sand", may be favorable for the formation of large-scale and contiguous buried-hill oil and gas reservoirs in the deep water areas in addition to the Central Canyon of the Qiongdongnan Basin.

       

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