鄂尔多斯盆地中央古隆起东侧非岩溶白云岩储层成因  

Genesis of non-karst dolomite reservoirs in the eastern central paleo-uplift in the Ordos Basin

作　　者：陈洪德[1,2] 胡思涵[1,2] 陈安清[1,2] 赵俊兴[1,2] 苏中堂[1,2] 

机构地区：[1]"油气藏地质及开发工程"国家重点实验室.成都理工大学 [2]成都理工大学沉积地质研究院

出　　处：《天然气工业》2013年第10期18-24,共7页Natural Gas Industry

基　　金：国家自然科学基金"中国南方中上扬子区叠合盆地沉积充填过程与物质分布规律"(编号:40739901)

摘　　要：近年来,鄂尔多斯盆地奥陶系马家沟组顶部除岩溶碳酸盐岩储层外,非岩溶白云岩储层也取得了天然气勘探突破。根据岩心观察、显微薄片鉴定、物性分析和测井录井等资料,研究了鄂尔多斯盆地中央古隆起东侧奥陶系马家沟组马五5―马五6亚段的沉积微相,分析了非岩溶白云岩储层特征及主控因素。结果表明:储集岩类型以砂砾屑白云岩和晶粒白云岩为主;储集空间类型主要为残余粒间孔、晶间孔和溶蚀孔,属非均质性较强的低孔隙度低渗透率储层;沉积环境为局限台地,包括潮缘滩、云坪、灰云质潟湖、灰质潟湖和膏质潟湖微相;储层分布明显受古隆起附近潮缘滩微相和选择性埋藏白云石化作用的控制;重结晶作用、胶结作用、压实压溶作用和充填作用等多种破坏性成岩作用导致了储层致密化;裂缝的存在改善了致密白云岩储层的物性,并且沟通了保存下来的孤立残余粒间孔和岩溶溶蚀孔。总之,潮缘滩微相中的埋藏白云石化、顺层岩溶作用和裂缝改造作用是储层发育的关键因素,有利于相对优质白云岩储层的形成。In addition to the successful exploration of carbonate karst reservoirs on the top of the Ordovician Majiagou Fm in the Ordos Basin, breakthroughs of gas exploration have also been made in nonkarst dolomite reservoirs. Core observation, thin section authentication, physical property analysis and logging data were integrated to study the sedimentary microfacies of Ma55 Ma56 （the 5th and 6th intervals of the fifth member of the Ordovician Majiagou Fm） on the east side of the paleouplift of the Ordos Basin, and to analyze the features and major control factors of the nonkarst dolomite reservoirs. The following findings were achieved. a. The reservoir rocks are dominated by dolarenitedolorudites and crystalline dolomites. b. The types of reservoir space are mainly of residual intergranular pores, intercrystalline pores and dissolution pores, indicating low porosity and low permeability reservoirs with strong heterogeneity. c. Their depositional settings are restricted platform which can be further divided into several sedimentary microfacies such as tidalfront beach, dolomitedominated tidal flat, dolomitedominated lagoon, limestonedominated lagoon and gypsumdominated lagoon, etc. d. The distribution of reservoirs is significantly controlled by the tidalfront beach microfacies near the paleouplift and selective burial dolomitization. e. Various destructive diagenesis such as recrystallization, cementation, compaction and pressure solution as well as filling led to the tightening of reservoirs. f. The development of fractures improves the physical properties of the dolomite reservoirs and connects the preserved isolated residual intergranular pores and dissolution pores. In summary, the burial dolomitization, alongbedding karstification and fracture modification in the tidalfront beach microfacies are the key factors controlling reservoir development, and are favorable for the development of relatively high quality dolomite reservoirs.

关 键 词：鄂尔多斯盆地 奥陶纪 白云岩 潮缘滩 沉积微相 致密储层 成岩作用 岩溶作用 裂缝改造 

分 类 号：P618.13[天文地球—矿床学]