塔里木盆地轮古西地区奥陶系古潜山岩溶作用机理与发育模式

Mechanism and development model of karsts in Ordovician buried hills in western Lungu area,Tarim Basin

轮古西地区奥陶系碳酸盐岩岩溶储集空间主要为溶蚀孔、洞、缝,岩溶储层类型可分为裂缝型、孔洞型、裂缝—孔洞型、洞穴型4种,具有极强的非均质性;不同地貌单元岩溶缝洞系统具有明显的垂向分带特征,应用薄片分析法对不同类型岩溶作用机理进行研究,在此基础上分析轮古西地区奥陶系碳酸盐岩岩溶储层发育模式。认为:东部轮古7井区区域位置最高,为轮南潜山区域补给区;轮古西地区岩溶台地为该区补给区,大气降水以下渗、径流为主,溶蚀孔洞及溶蚀裂缝发育,泥质、方解石充填;岩溶坡地为地下水径流区,地下水以水平径流为主,岩溶暗河管道系统发育,岩溶角砾岩、泥质充填;岩溶盆地为排泄区,其排泄基准面决定了岩溶发育规模。

In the western Lungu area in the Tarim Basin,dissolution pores,holes and fractures served as reservoir space in the Ordovician carbonate rocks. The karst reservoirs had a strong heterogeneity,and were classified into four types,including fracture,hole,fracture-hole,and cave. In different landscape units,the karsted fracture and hole system was vertically zoned. The mechanism of karst was studied with sheet analysis,and a developmentmodel of the karst reservoir in the Ordovician western Lungu carbonate rocks was established. The Lungu7 block in the east was the highest in the study area,and recharged the buried hills in Lunnan. The karst platform in the western Lungu area recharged the western Lungu area. Meteoric water infiltrated,forming dissolution pores and fractures,which were filled by clays and calcites. On the karst slope,groundwater migrated horizontally,and a karst river / pipeline system developed,filled by karst breccias and clays. The karst basin drainage area determined the scale of karst development.