1.China Oil&Gas Survey;2.China Geological Survey & Oil and Gas Survey;3.Research Institute of Petroleum Exploration & Development;4.Hubei Geological Survey
The project of China Geological Survey (No.DD20190088)
研究目的：中上扬子地区在新元古代南华纪中期发育大塘坡组海相黑色含锰碳质页岩，长期以来作为锰矿层被广泛关注，但其油气地质特征研究较少。本文从油气地质角度，对大塘坡组岩相古地理及其对油气成藏的指示作用进行阐述，以对南方地区油气调查进行指导。 研究方法：通过野外地质调查和资料收集，采用单井分析、连井对比、岩相古地理图编制等方法，结合烃源岩特征分析、储层分析等实验测试手段，对大塘坡组沉积特征和油气地质条件进行了梳理，并对其烃源岩特征和潜在油气组合进行了分析。 研究结果：大塘坡组形成于间冰期，沉积过程受拉张裂陷过程控制，可划分出2大类沉积相、7类沉积亚相及若干微相，整个沉积期构成一个完整的海侵—高位—海退沉积旋回；大塘坡组最具有油气资源潜力的相带为局限陆棚亚相和潟湖亚相，主要分布在大塘坡组一段，有机地球化学指标特征好，为优质烃源岩。 结论：大塘坡组一段具有良好的生烃潜力和页岩气发育潜力，松桃、花垣、秀山、湘潭、鹤峰等地区具有页岩气发育有利条件，为潜在页岩气发育区。以大塘坡组为烃源岩发育多种成藏组合，渝黔湘交界的秀山、松桃、花垣地区，源储配置条件较好，为潜在常规油气发育区。
Objective: Marine black manganese-bearing carbonaceous shale of Datangpo Formation was generally developed in the mid-Neoproterozoic Nanhua period in the Middle-Upper Yangtze Region，South China, which has been widely concerned as a manganese deposit for a long time, but with little attention to its petroleum geological characteristics. This paper expounds the lithofacies paleogeography of the Datangpo Formation and its indication of oil and gas accumulation, so as to guide the oil and gas investigation in the Suthern China. Methods: Through field investigation and data collection on the Datangpo Formation, the oil and gas geological conditions, the source rock characteristics and hydrocarbon accumulation assemblage, especially lithofacies and paleogeography, were systematically analyzed by methods of single well analysis, continuous well comparison, lithofacies paleogeographic map compilation, etc., combined with source rock characteristic analysis, reservoir analysis and other experimental testing methods. Results: The Datangpo Formation was formed during the interglacial period, and the depositional process was controlled by the extensional rifting process. Its sedimentary facies can be divided into two types, seven subtypes and several microfacies. The entire depositional period constitutes a complete transgressive-Highstand-Regressive sedimentary cycle; the most potential facies belts for oil and gas resources in the Datangpo Formation are limited shelf subfacies and lagoon subfacies, mainly distributed in the first member, with good organic geochemical index characteristics, and are high-quality source rocks. Conclusions: The first member of the Datangpo Formation has good hydrocarbon generation and shale gas development potential. Songtao, Huayuan, Xiushan, Xiangtan, Hefeng and other areas at the junction of Hunan, Chongqing and Guizhou Province have favorable conditions for shale gas development and are potential shale gas development areas. With the Datangpo Formation as the source rock, a variety of potential reservoir-forming assemblages can be formed. The Xiushan, Songtao and Huayuan areas at the junction of Chongqing, Guizhou and Hunan Province have good source-reservoir configuration conditions and are potential conventional oil and gas development areas.