鄂尔多斯盆地中东部奥陶系马五41a储层特征及成因  

Reservoir characteristics and genesis of O1m54-1a in the central and eastern Ordos Basin

作　　者：于洲 周进高[1,2] 丁振纯 魏柳斌[3] 魏源 吴兴宁[1,2] 吴东旭[1,2] 王少依 李维岭[1,2] YU Zhou;ZHOU Jin-gao;DING Zhen-chun;WEI Liu-bin;WEI Yuan;WU Xin-ning;WU Dong-xu;WANG Shao-yi;LI Wei-ling(PetroChina Hangzhou Research Institute of Geology,Hangzhou 310023,China;Key Laboratory of Carbonate Reservoirs,CNPC,Hangzhou 310023,China;Exploration and Development Research Institute,PerroChina Changqing Oilfield Company,Xi’an 710018,China)

机构地区：[1]中国石油杭州地质研究院,浙江杭州310023 [2]中国石油天然气集团公司碳酸盐岩储层重点实验室,浙江杭州310023 [3]中国石油长庆油田分公司勘探开发研究院,陕西西安710018

出　　处：《天然气地球科学》2020年第5期686-697,共12页Natural Gas Geoscience

基　　金：中国石油科技重大项目“古老碳酸盐岩油气成藏分布规律与关键技术”(编号:2019B-0405、2019B-0406);中国石油科技重大项目“深层油气储集层形成机理与分布规律”(编号:2018A-0103);中国石油科技重大专项“长庆油田5000万吨持续高效稳产关键技术研究与应用”(编号:2016E-0512、2016E-0514)联合资助.

摘　　要：马五41a小层是鄂尔多斯盆地奥陶系天然气勘探新层系,有望成为继马五1+2风化壳气藏后又一个储量产量规模增长区。为此,依据钻井岩心、微观薄片、阴极发光、物性数据和地球化学特征等资料,研究鄂尔多斯盆地中东部奥陶系马五41a储层特征及成因。结果表明:①马五41a储层岩性为含硬石膏细粉晶白云岩,储集空间主要为硬石膏结核溶模孔,含少量硬石膏晶体铸模孔和微裂缝,平均孔隙度为5.54%,平均渗透率为1.53×10-3μm2;②储层孔隙经历了硬石膏沉淀,大气淡水溶蚀作用,中晶方解石、石英、中-粗晶白云石和巨晶方解石充填作用和破裂作用;③古地貌控制的差异溶蚀作用与差异充填作用控制了储层的平面分布。综合分析认为,榆林-靖边-延安以西的沉积古地貌高部位与岩溶斜坡叠合区域和红墩界-青阳岔地区储层溶蚀作用强,充填程度低,是优质储层的分布区,为下一步勘探部署提供了理论依据。O1m54-1a is a new formation of Ordovician natural gas exploration in Ordos Basin,which is expected to be another area with large-scale increase of reserves and production after O1m51+2 weathering crust gas reservoir.Based on drilling core,thin section,cathodoluminescence,physical property data,and geochemical characteris⁃tics,genesis and distribution of the reservoirs of the O1m54-1a in the central and eastern parts of the Ordos Basin are studied.The results showed:(1)The lithology of the reservoir of the O1m54-1a is dolomudstone with nodular anhydrite.The storage space is mainly the dissolution of anhydrite moldic pores,containing a small amount of anhydrite crystal moldic pores and micro-cracks,and the average porosity is 5.54%;the average permeability is 1.53×10−3μm2.(2)The reservoir pore experienced anhydrite precipitation,and atmospheric fresh water disso⁃lution,and mesocrystalline calcite filling,and quartz filling,and medium coarse crystal dolomite filling,and megacryst calcite,and rupture;(3)Differential dissolution and filling controlled by paleogeomorphology control the plane distribution of reservoir.The comprehensive analysis shows that the congruent area between high part of sedimentary paleogeomorphology and karst slope locating at the west of Yulin-Jingbian-Yan'an and the Hong⁃dunjie-Qingyangcha area has strong dissolution and low filling degree,which is the distribution area of high-qual⁃ity reservoir,providing theoretical basis for the next exploration and deployment.

关 键 词：鄂尔多斯盆地 马五41a小层 古地貌 溶蚀作用 充填作用 

分 类 号：TE122.2[石油与天然气工程—油气勘探]