塔中北斜坡奥陶系鹰山组碳酸盐岩古岩溶发育,油气资源丰富,具有广阔的勘探开发前景。本次利用岩石化学分析、岩芯钻井、地震测井及成像测井资料,对岩溶储层发育规律及岩溶缝洞发育模式进行研究。认为:鹰一段和鹰二段发育质纯厚层灰岩地层,属强岩溶层组,溶蚀孔,溶蚀裂缝及溶洞均发育,后期古岩溶作用是该区油气聚集的主要场所。垂向岩溶缝洞系统主要发育在鹰山组顶面以下0-50 m及80-180 m范围。同时,溶洞在该区发育,洞穴型岩溶是该区优质岩溶储层,钻井过程常伴有放空、水漏失现象。结合古地貌特征,建立了ZG18-ZG22井区古岩溶缝洞系统发育模式,为岩溶储层预测及勘探开发井位部署提供地质依据。
The study area is situated in the northern slopes of Tazhong paleo-uplift, Tarim basin, where pal-eokarstic features are massively developed in the carbonate rocks of Yingshan Formation of the Ordovician, with abundant oil and gas resources and a broad prospect for the exploration and development of the natural resources. The development of karst reservoir and the patterns of solution cavities and fissures were studied, based on the data derived from rock chemical analysis, core drilling, and down-hole seismic and imagining logs. The results show that thick-layered pure limestone of the top two members of Yingshan Formation be- longs to strong karst suite, where corrosion hole, karst fissure and cave are developed. Post tectonic karstification has made the region become the main place for oil-gas accumulation. The results also show that vertical karst caves and solution fissures mainly occur in the depth ranges of 0 - 50 m and 80-180 m below the Yingshan Formation, of which the karst caves substantially constitute the oil gas reservoir in this area. This was confirmed by the venting and leaking phenomena during the well drilling. In combination with the char- acteristics of paleo-geomorphology, we established the development patterns of paleokarstic cave system in the area between wells ZG18 and ZG22,in order to provide a concrete geological basis for karst reservoir prediction and well exploration.