鄂尔多斯盆地姬塬西部三叠系延长组长8油层组成岩作用与致密化过程

发布时间：2018-02-26 19:27

本文关键词： 储集层致密化过程致密化成因成岩作用三叠系延长组长油层组姬塬西部鄂尔多斯盆地　出处：《古地理学报》2017年05期 　论文类型：期刊论文

【摘要】：利用岩心、铸体薄片、扫描电镜、碳氧同位素及流体包裹体等资料,对鄂尔多斯盆地姬塬西部三叠系延长组长8油层组致密储集层特征进行了研究,重点分析了储集层成岩作用特征和储集层致密化成因机制及过程。研究区长8油层组砂岩主要为岩屑长石砂岩和长石岩屑砂岩,经历了压实—压溶、胶结、交代、溶蚀及构造破裂等成岩作用,整体处于中成岩A期晚期。典型成岩序列依次为机械压实、绿泥石黏土膜、早期(泥晶)方解石胶结、石英次生加大、长石、岩屑溶蚀、自生高岭石胶结、自生石英胶结、中期(含)铁方解石胶结。综合研究认为:(1)近物源伴随湖平面快速上升的沉积环境提供了储集层致密化的物质基础,不同沉积微相储集层物性差别较大,分流河道最好,分流间湾最差;(2)长8油层组原始孔隙度为41.35%,压实作用损孔率为50.67%,造成储集层孔隙度急剧降低,胶结作用损孔率为37.48%,导致孔隙度进一步减小,溶蚀作用仅增加了3.26%的孔隙度,难以有效改善储集层质量;(3)上述沉积与成岩因素共同导致储集层致密,致密化过程可分为压实孔隙骤减阶段、早期胶结减孔阶段、溶蚀作用增孔阶段和晚期胶结致密阶段共4个阶段;(4)油气大量充注期储集层孔隙度远低于10%,长8油层组先致密后成藏。
[Abstract]:Based on the data of core, thin section of cast body, scanning electron microscope, carbon and oxygen isotopes and fluid inclusions, the characteristics of dense reservoirs in the Chang 8 formation of the Triassic Yanchang formation in western Jiyuan, Ordos Basin were studied. The characteristics of reservoir diagenesis and the mechanism and process of reservoir densification are emphatically analyzed. The sandstone of Chang 8 oil formation in the study area is mainly lithic feldspathic sandstone and feldspathic sandstone, which has experienced compact-pressure solution, cementation and metasomatism. The diagenesis, such as dissolution and structural fracture, is in the late stage A of middle diagenesis. The typical diagenetic sequence is mechanical compaction, chlorite clay film, early (mud-crystal) calcite cementation, secondary increase of quartz, dissolution of feldspar and lithic debris. Authigenic kaolinite cementation, authigenic quartz cementation, intermediate (including) iron calcite cementation. It is considered that the sedimentary environment of near provenance accompanied by rapid rise of lake level provides material basis for reservoir densification. The physical properties of different sedimentary microfacies reservoirs differ greatly, the distributary channel is the best, the original porosity of Chang 8 reservoir formation is 41.35 and the compaction porosity is 50.67, which results in a sharp decrease of reservoir porosity. The loss of porosity due to cementation is 37.48%, which leads to further decrease of porosity, while dissolution only increases porosity by 3.26%, so it is difficult to improve reservoir quality effectively. The densification process can be divided into compaction pore reduction stage and early cementation reducing pore stage. The porosity of reservoir during the massive oil and gas filling period is much lower than that of 10 layers, and Chang 8 reservoir group is densified first and then formed reservoir.
【作者单位】：中国石油大学(北京)油气资源与探测国家重点实验室;中国石油大学(北京)盆地与油藏研究中心;甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室;
【基金】：国家自然科学基金项目(编号:41372143) 教育部高等学校博士学科点专项科研基金项目(编号:20130007110002) 中国科学院“西部之光”项目(编号:1007RJYA013)联合资助~~
【分类号】：P618.13

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