摘要:
歧南断阶带侏罗系储层内部结构复杂,具有强储层非均质性,储层发育特征及影响因素一直制约着该区勘探。通过对岩石类型、储层物性特征、储集空间类型及孔隙结构的分析证实,研究区侏罗系为一套富含火山碎屑物质的近源沉积,发育多套煤层;储层物性以中孔低渗为主,发育低渗背景下的优质储层,孔隙结构分析表明不同孔隙结构储层在孔隙度方面相差不大,渗透率相差较大;储集空间以溶蚀形成的次生孔为主,多为长石及火山物质溶蚀;有利的沉积因素,多期次多类型的溶蚀作用是本区形成优质储层的主要因素,研究区煤系地层的存在有效地增加了有机酸浓度,在促进溶蚀作用进行的同时,减少了碳酸盐矿物的胶结;此外储层中大量发育的火山碎屑物质在酸性流体下易于溶蚀,增强了储集物性,但其也降低了岩石抗压能力,对储层物性的影响具有双面性。
Abstract:
The Jurassic reservoir in the Qinan fault step belt is heterogeneous due to complex internal textures. It is one of the major problems faced in oil exploration. Based on the study of rock types, reservoir physical properties, reservoir space types and pore structures, it is concluded that the Jurassic of the area is a kind of proximal sediments rich in pyroclastic materials intercalating coal seams. The reservoir is characterized by medium porosity and low permeability. High quality reservoirs are sometimes found in the low permeability sequence. Pore structure analysis shows that permeability may change greatly though the porosity remains similar. Secondary pores caused by multi-cyclic dissolution of feldspar and volcanic materials dominate sometimes. The quality of reservoirs depends upon the dissolution by acidic fluids. The coal strata are believed the source of organic acids, which promoted the dissolution and the reduction of carbonate minerals. The pyroclastic materials have double affect on the reservoir, on the one hand, they are apt to be corroded and dissolved to increase the reservoir porosity and block the process of quartz overgrowth, on the other hand, it may reduces the compaction of sediments which are favorable for reservoir properties.
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