摘要
川东北元坝地区多口井在上三叠统须家河组三段(须三段)钙屑砂岩储层中获中—高产工业气流,表明该段具有良好的勘探开发潜力,然而对须三段储层发育控制因素尚缺乏清晰的认识,制约了勘探开发部署。综合利用岩心观察、薄片鉴定、物性分析等结果,对该区须三段储层特征及成岩作用进行了研究,分析了沉积、成岩对储层发育的控制作用。结果表明,元坝地区须三段北西—南东向地层厚度变化大,呈明显的"西北厚、东南薄"的进积特征,属于进积式辫状河三角洲沉积。储层以钙屑砂岩为主,主要储集空间为溶孔、微溶孔等,物性为特低孔-特低渗、非均质性强。压实-压溶、胶结充填、溶蚀、重结晶、破裂等成岩作用在须三段储层成岩演化过程中较发育。就孔隙发育而言,建设性成岩作用主要为埋藏溶蚀和破裂作用等,压实和方解石胶结是重要的破坏性成岩作用。元坝地区须三段辫状河三角洲平原与前缘相对富煤的沉积环境及其中的煤系烃源岩,在生排烃演化过程中,其控制了(水下)分流河道钙屑砂岩储层埋藏溶蚀成岩作用的发育。综上所述,(水下)分流河道沉积微相是须三段钙屑砂岩孔隙发育的基础,埋藏溶蚀、破裂作用等成岩作用有利于储层孔隙的形成和改善。因此,(水下)分流河道中薄煤层或煤层夹层相对发育区,以及断裂、裂缝相对发育区为川东北元坝地区须三段储层发育有利区。
Medium and high production commercial gas flow was found from several wells of the third member of Upper Triassic Xujiahe Formation in Yuanba area of northeastern Sichuan Basin,which shows better exploration and development potential here.The controlling factors of reservoir development of the third member of Xujiahe Formation are not clearly understood,which restricts the exploration and development deployment.The data of core observation,thin section identification and physical property analysis were used to study the reservoir characteristics and diagenesis of Xu 3 member,and the control of sedimentation and diagenesis on reservoir development was analyzed.The results show that the strata of Xu 3 member are relatively instable in thickness with the characteristics of thick in northwest and thin in southeast,and belong to progradational braided river delta deposits.Reservoir rocks,which mainly belong to calcarenaceous sandstones with the characteristics of dissolved pores,microscopic dissolved pores,have the characteristics of super-low porosity and super-low permeability with strong heterogeneity.Reservoir diagenesis mainly includes compaction,cementation,dissolution,recrystallization and fracturing.For pore development,constructive diagenesis mainly includes burial dissolution and fracturing,and compaction and calcite cementation belong to important destructive diagenesis.In Yuanba area,calcarenaceous sandstones deposited in the braided river delta plain-front are the most favorable sedimentary microfacies.For reservoir development,the burial dissolution diagenesis could be controlled by the relatively coal-rich sedimentary environment of braided river delta plain-front to a certain extent.In conclusion,the sedimentary microfacies of underwater distributary channel and plain distributary channel in braided river delta front and plain is the foundation of pore development of calcareous sandstone of Xu 3 member.Diagenesis such as burial dissolution and fracturing is conducive to the formation and improvement of reservoir pores.Therefore,the relatively developed areas of thin coal seam or coal seam interlayer in distributary channel and the relatively developed area of faults and fractures may be favorable for reservoir development district.
作者
郑荣臣
李宏涛
史云清
肖开华
ZHENG Rongchen;LI Hongtao;SHI Yunqing;XIAO Kaihua(Research Institute of Exploration and Production,Sinopec,Beijing 100083,China;Key Laboratory for Marine Oil and Gas Exploitation,Sinopec,Beijing 100083,China)
出处
《岩性油气藏》
CSCD
北大核心
2021年第3期13-26,共14页
Lithologic Reservoirs
基金
国家科技重大专项“大型油气田及煤层气开发”(编号:2016ZX05002-006)
中国石化科技部项目“杭锦旗十里加汗复杂气藏定量表征及开发对策”(编号:P19019-1)
“东胜气田精细表征及有效开发技术”(编号:P20065-2)联合资助。
关键词
钙屑砂岩
沉积相
储层
成岩作用
须三段
川东北元坝地区
calcarenaceous sandstones
sedimentary facies
reservoir
diagenesis
the third member of Xujiahe Formation
Yuanba area in northeastern Sichuan Basin