深层复杂储集体优质储层形成机理与油气成藏--以济阳坳陷东营凹陷古近系为例

摘要

The genetic mechanism and hydrocarbon accumulation of quality reservoirs in the deep complex Paleogene re-servoir rocks of Dongying Sag are studied by core observation,thin section analysis,petrophysical testing,isotope testing and well testing.The studies show that the secondary porosity resulted from alternative dissolution of acid-alkaline fluids improved the local physical properties of deep reservoirs to some extent and is the key to the formation of the deep quality reservoirs.The reservoirs in different deep sequences have different genetic mechanisms,reflecting the differences in ori-ginal components,fluid environment,source-reservoir combination and other conditions.The quality reservoirs of red beds in fulvial-alluvial fans of the initial rifting sequences were formed in alkaline environment and contacted laterally with source rocks,featuring in not only the dissolution of large amount of feldspar and carbonate,but also the intensive dissolu-tion of quartz.The quality coarse clastic reservoirs of steep slope fan delta and underwater fan in the expanded rifting se-quences are in interfingered contact with source rocks,and connected with deep alkaline fluids through basin-controlling faults,featuring in the erosion of large amount of feldspar and carbonate but just a small amount of partial quartz.The quality reservoirs of beach bar sands and turbidite in the expanded rifting sequences mostly occur in the source rocks,fea-turing in the erosion of feldspar and carbonate.The fault terrace zones on ramp are on the major migration pathway,thus the quality red reservoirs juxtaposing with the source rocks are favorable for hydrocarbon accumulation.The quality coarse clastic reservoirs in middle-fan that are screened by root-fan of steep slope are favorable for hydrocarbon accumulation. The quality beach bar sands and turbidite reservoirs that are in source rocks with high pressure are favorable for hydrocar-bon accumulation.%综合运用岩心观察、薄片分析、岩石物性测试、同位素测试以及试油、试采结果分析等方法，对济阳坳陷东营凹陷古近系深层复杂储集体优质储层形成机理与油气成藏过程进行了研究。研究表明，酸－碱流体交替溶蚀作用形成的次生孔隙在一定程度上改善了深层局部储层物性，是深层优质储层形成的关键。深层不同层序沉积物原始组分、流体环境、源－储配置等条件的不同，使优质储层的形成机理存在差异。初始裂陷层序河流－冲积扇红层优质储层发育于碱性环境，且与烃源岩侧向接触，不仅发生大量的长石和碳酸盐岩溶蚀，石英也发生强烈的溶蚀。扩展裂陷层序陡坡扇三角洲、水下扇砂砾岩优质储层与烃源岩呈指状接触，且通过控盆断层与深部碱性流体沟通，主要表现为长石和碳酸盐岩溶蚀，石英只是局部少量溶蚀。扩展裂陷层序滩坝砂和浊积岩优质储层大部分分布于烃源岩中，主要表现为长石和碳酸盐岩的溶蚀。缓坡断阶带处于流体优势运移通道，与烃源岩对接的红层优质储集有利于成藏。陡坡带扇根遮挡的扇中砂砾岩优质储层有利于油气成藏。处于生烃增压烃源岩中，发生成岩耗水的滩坝砂和浊积岩优质储层有利于成藏。