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鄂尔多斯盆地东南部延长天然气探区下二叠统山西组山2段成岩作用复杂,主要结合普通薄片、铸体薄片、扫描电镜等资料对山2段成岩作用进行系统研究,确定研究区储层经历了压实作用、胶结作用、交代作用和溶解作用等多种成岩作用。根据山2段填隙物的胶结类型、颗粒的接触性质、物性数据和成岩作用特征,在研究区划分出5种成岩相:Ⅰ类,弱压实—黏土薄膜—石英弱加大胶结溶蚀相;Ⅱ类,中压实—硅质胶结溶蚀相;Ⅲ类,中压实—黏土杂基充填微孔相;Ⅳ类,强压实—硅质胶结致密相;Ⅴ类,强压实黏土充填致密相。另外结合试气资料,确定Ⅰ类、Ⅱ类、Ⅲ类这3类成岩相为储集层发育的优势成岩相带。最后根据储层岩石学特征、物性特征、沉积相以及成岩相分析优质储层发育特征,以期为有利成藏区带预测提供依据。
The diagenesis of the Lower Member of the Member 2 of the Lower Permian Shanxi Formation in the Lower Permian natural gas exploration area in the southeastern Ordos Basin is complicated. The diagenesis of the Member 2 is systematically studied with the help of ordinary thin slices, cast thin slices and scanning electron microscopy. A variety of diagenesis, such as compaction, cementation, metasomatism and dissolution. According to the cementation type, the contact properties, physical property data and diagenetic characteristics of the sandstone in the second member, five diagenetic facies are classified in the study area: Class Ⅰ, weakly compacted - clay film - quartz weakly increase the cementation dissolution phase Class II, intermediate-compacted-siliceous cemented-dissolution facies; Class III, medium-compacted-clay miscellaneous-filled microporous facies; Group IV, strongly compacted-siliceous cemented facies; Dense phase In addition, combined with the test data, three types of diagenetic facies, such as Ⅰ, Ⅱ and Ⅲ, are identified as the dominant diagenetic facies belts developed in the reservoir. Finally, according to reservoir petrology, petrophysical characteristics, sedimentary facies and diagenetic facies, the developmental characteristics of high-quality reservoirs are analyzed in order to provide evidences for the prediction of favorable reservoiring zones.