差异成岩作用对致密砂岩储集性能的影响——以鄂尔多斯盆地吴起-顺宁地区延长组长8_(1)亚段为例  

Impact of differential diagenesis on the reservoir quality of tight sandstone:An example from Chang 8_(1)submember,Wuqi-Shunning area,Ordos Basin

作　　者：岳怀海 冯明友[1] 刘小洪[1] 肖文联[2] 石坚 李月娥 曹娟 YUE Huaihai;FENG Mingyou;LIU Xiaohong;XIAO Wenlian;SHI Jian;LI Yue’e;CAO Juan(School of Geosciences and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;School of Petroleum Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi’an,Shaanxi 710018,China)

机构地区：[1]西南石油大学地球科学与技术学院,四川成都610500 [2]西南石油大学石油与天然气工程学院,四川成都610500 [3]中国石油长庆油田公司勘探开发研究院,陕西西安710018

出　　处：《天然气勘探与开发》2025年第2期26-38,共13页Natural Gas Exploration and Development

基　　金：国家科技重大专项(编号:2017ZX05001001)。

摘　　要：鄂尔多斯盆地三叠系上统延长组长8油层组是该盆地致密油的勘探目的层之一,相继发现了姬塬、西峰、马岭地区等特大油田,展示出巨大的油气勘探潜力。为了深入研究沉积、成岩作用等控制下的该盆地致密砂岩有效储层分布规律,基于岩心观察、铸体薄片鉴定、扫描电镜及物性分析等实验测试结果,以吴起—顺宁地区延长组长8_(1)亚段储集层为研究对象,开展岩石学特征、成岩作用及物性特征等综合研究,明确了成岩相带分布,进而预测了有利储层发育区。研究结果表明:①研究区长8_(1)亚段储集岩岩石类型主要为细—中粒长石砂岩及岩屑长石砂岩,储集空间以粒间孔和长石溶孔为主,为特低孔隙度、超低渗透率储层;②主要建设性成岩作用为溶蚀作用,破坏性成岩作用为压实及胶结作用,吴起地区溶蚀作用强度略高于顺宁地区,而压实—胶结作用强度则明显低于顺宁地区;③综合成岩矿物、成岩作用类型及成岩作用强度等因素,在研究区共划分出5类成岩相——碳酸盐+伊利石胶结致密相、压实压溶致密相、自生黏土+碳酸盐胶结相、绿泥石薄膜胶结+溶蚀相、石英加大胶结+溶蚀相,其中后两者为最有利于储层发育的成岩相。结论认为,研究区吴起中部及顺宁中部为最有利的成岩相及储层发育区。Being an important exploration target of tight oil in Ordos Basin,the eighth member of the Upper Triassic Yanchang Formation(Chang 8 Member)has been discovered from several super-giant oilfields in Jiyuan,Xifeng,Maling areas,suggesting great exploration potential.Therefore,the first submember of Chang 8 Member(Chang 8_(1)submember)in Wuqi–Shunning area was taken as an example to discuss the distribution of effective tight sandstone reservoirs affected by both sedimentation and diagenesis in this basin.For Chang 8_(1)reservoirs,the petrology,diagenesis and physical properties were studied through core observation,cast thin-section observation,scanning electron microscopy(SEM)and physical property analysis.In addition,the distribution of diagenetic facies belts was figured out,and some favorable zones were predicted for reservoir extension.Results show that(i)characterized by extremely low porosity and permeability,these Chang 8_(1)reservoirs with intergranular pores and feldspar dissolved pores as the dominant reservoir space are dominated by fine-to medium-grained feldspathic sandstone and lithic feldspathic sandstone;(ii)dissolution is deemed as the main constructive diagenesis while both compaction and cementation as destructive one.This dissolution in Wuqi has slightly higher intensity than that in Shunning,whereas the compaction and cementation intensity in Wuqi evidently lower than that in Shunning;and(iii)five diagenetic facies can be divided in the study area in line with diagenetic minerals and diagenesis type and intensity,including carbonate+illite cemented tight facies,compaction-pressolution tight facies,authigenic clay+carbonate cemented facies,chlorite thin-film cementation+dissolution facies,and quartz-enlarged cementation+dissolution facies,among which the latter two are most favorable for reservoir extension.In conclusion,the central Wuqi–Shunning area is in favor of diagenetic facies and reservoir extension.

关 键 词：鄂尔多斯盆地 三叠系上统延长组 致密砂岩 储集层 成岩作用 溶蚀作用 

分 类 号：P618.13[天文地球—矿床学]