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综合应用地质、地震、地球化学及井筒岩电等资料,运用成藏动力学等手段,对文昌A凹陷恩平组异常高压的分布、成因及其与油气成藏的关系进行了系统研究。结果表明:凹陷中心恩平组普遍发育异常高压,超压形成的主要原因是早渐新世泥岩快速沉降形成的欠压实作用及后期的生烃作用;恩平组高压幕式排烃、运移形成珠海组、珠江组2套有利的成藏组合,其中珠海组二、三段是处于正常压力带—压力过渡带的低孔低渗成藏组合,珠江组是处于正常压力带的成油组合,这2套成藏组合具有不同的运移特征及成藏期次,形成了“凹中深层聚气、斜坡聚油气及隆起聚油”的油气分布格局。根据上述新认识提出了2种成藏模式,即陡坡带垂向运聚模式和缓坡带垂向+侧向运聚模式,认为凹陷北部缓坡带和珠三南断裂下降盘是下步勘探的重要方向。
By comprehensively applying the data of geology, earthquake, geochemistry and wellbore rockwell electricity, the distribution and genesis of anomalous high pressure in Enping Formation of Wenchang A depression and its relationship with hydrocarbon accumulation are systematically studied by means of reservoir dynamics and so on. The results show that the Enping Formation in the depression center is generally under abnormally high pressure, and the over-pressure is mainly due to the under-compaction caused by the rapid subsidence of the Early Oligocene mudstone and the hydrocarbon generation in the later stage. The second and third stages of the Zhuhai Formation are low-porosity and low-permeability reservoir assemblages in the normal pressure belt-pressure transition zone. The Zhujiang Formation is an oil-forming unit in the normal pressure zone The combination of these two sets of reservoirs has different migration characteristics and stages of hydrocarbon accumulation, resulting in the distribution pattern of oil and gas in the “concave deep gas, ramp poly oil and uplift oil”. Based on the above new understanding, two kinds of accumulation models are proposed, that is, the vertical migration and accumulation mode of steep slope belt and the vertical + lateral migration and accumulation mode of gentle slope belt. It is considered that the gentle slope zone in the north depression and the descending slope of the Zhuangnanan fault are important for the next exploration direction.