风化壳古岩溶垂向分带与储集层评价预测——以鄂尔多斯盆地中部气田区马家沟组马五_5—马五_1亚段为例  

Vertical zonation of weathered crust ancient karst and the reservoir evaluation and prediction——A case study of M_5~5-M_5~1sub-members of Majiagou Formation in gas fields, central Ordos Basin, NW China

作　　者：何江[1,2] 方少仙[1] 侯方浩[1] 阎荣辉[3] 赵忠军[3] 姚坚[3] 唐秀军[3] 吴国荣[3] 

机构地区：[1]西南石油大学资源与环境学院 [2]成都理工大学地球科学学院 [3]中国石油长庆油田公司

出　　处：《石油勘探与开发》2013年第5期534-542,共9页Petroleum Exploration and Development

基　　金：国家油气重大专项'岩性地层油气藏成藏规律;关键技术及目标评价'(2011ZX05001)

摘　　要：以鄂尔多斯盆地中部气田区中奥陶统马家沟组马五5—马五1亚段为例,通过大量岩心及薄片观察,以地质背景和古岩溶岩石学特征为主线,解剖风化壳古岩溶垂向分带特征,并进行储集层评价预测。通过详细的井下地质调查、典型岩溶剖面写实、系统取样和室内测试等研究发现,研究区马家沟组顶部古风化壳主要发育岩溶建造岩和岩溶改造岩,由地表到地下可分为地表岩溶带、垂直渗流带、水平潜流带和深部缓流带。各带中岩溶强度对于储集层储渗能力影响极大,水平潜流带强溶蚀亚带岩溶强度过高,母岩被大面积破坏形成岩溶溶洞,其中充填了基本无孔隙的岩溶建造岩;深部缓流带岩溶强度过低,以沉淀和充填作用为主;而水平潜流带中等溶蚀亚带、垂直渗流带岩溶强度适中,有效的溶蚀既形成了储渗空间,又不至于崩塌破坏,最有利于储集层发育。The M55-M51 sub-members of the Middle Ordovician Majiagou Formation in gas fields of central Ordos Basin were taken as a case to analyze the vertical zonation characteristics of weathered crust ancient karst and to evaluate and predict reservoirs through plenty of core and thin section observation, with geological background and petrological characteristics as main clue. According to detailed underground geological survey, description of typical karst section, systematic sampling, and laboratory test, there mainly developed karst formation rock and transformation rock in ancient weathered crust in the top of the Majiagou Formation, which were divided into surface karst zone, vertical vadose zone, horizontal underflow zone and deep slow flow zone from surface to subsurface. Karst intensity in each zone has great effect on the storage and flow capacity of reservoir. In the strong karstification snbzone of the horizontal underfiow zone with over strong karst, the parent rock was extensively damaged and formed karst caves filled with karst formation rock rarely with pores. In the deep slow flow zone with over weak karstification, there are sedimentary and filling activities. The medium karstification subzone of the horizontal underflow zone and the vertical seepage zone had a moderate karstification, which not only created storage and flow space but also prevented collapse, and were most beneficial to reservoir development.

关 键 词：风化壳古岩溶 垂向分带 储集层评价预测 鄂尔多斯盆地 马家沟组 

分 类 号：TE122.1[石油与天然气工程—油气勘探]