塔里木盆地深层、超深层白云岩优质储集层测井预测*

塔里木盆地寒武系白云岩是深层、超深层油气勘探的重要接替层系,但该套白云岩具有时代古老、埋藏深、成岩和构造演化复杂的特征,亟需在揭示储集层成因基础上建立不同成因白云岩储集层配套测井评价方法。由此通过岩心、薄片观察,结合常规和成像测井首先从储集层孔隙成因角度出发,识别出“岩溶改造型”和“沉积相控型”两大类白云岩。岩溶改造型白云岩储集层质量受岩溶相带控制,纵向可划分出表层岩溶带、垂直渗流带、水平潜流带和深部缓流带4个岩溶相带。沉积相控型白云岩储集层物性则受沉积相带控制,颗粒滩等高能沉积相决定了储集层质量。通过岩心刻度常规和成像测井分别建立岩溶相带以及沉积微相的测井识别模式与准则,实现了单井岩溶相带和沉积微相的测井识别与划分。最后在岩溶相带和沉积微相约束下实现单井白云岩储集层综合评价以及有利发育区带预测。岩溶改造型白云岩储集层,其垂直渗流带与水平潜流带分别以高角度裂缝和水平溶蚀孔洞为主要特征,可形成有利储集体发育的缝洞系统。沉积相控型白云岩,其中的颗粒滩和云坪高能相带原始孔隙发育,且也有利于进一步溶蚀,因此物性较好。研究成果可为深层、超深层白云岩有利储集层分布预测提供理论指导和技术支撑。

Prediction of high quality deep and ultra-deep dolostones reservoirs in Tarim Basin by well logs

The Cambrian dolostone is one of the most important exploration targets of deep and ultra-deep strata in Tarim Basin. However,it has characteristics of ancient geological age,deep burial,and complex tectonic and diagenetic evolution. Therefore,it is of great significance to understand the genetic mechanism,and establish a matched well logs evaluation method for various kinds of dolostone. Based on the comprehensive observation of core,thin section,conventional and imaging logs,two types of dolostone i.e. ,“karst transformation type”and “sedimentary facies dominated”are recognized in the Tarim Basin. The karst transformation dolostone reservoir are controlled by karst facies belt and can be divided into four zones in the vertical direction,namely the surface karst zone,vertical vadose zone,horizontal hyporheic zone and deep slow flow zone. The reservoir quality of depositional facies controlled dolostone is evidently controlled by high energy depositional facies such as the grain bank. The recognition patterns of karst dissolution belt and sedimentary microfacies by conventional and imaging logs data and marked by core sample are established and applied in the comprehensive interpretation of dolostone reservoir in the single well and prediction of favorable development area. The high angle fractures and horizontal dissolution vugs in the vertical vadose zone,horizontal hyporheic zone are favorable for the formation of high quality karst transformation type dolostone with fracture-cave system. The high energy depositional facies(shoal and reef facies,and tidal flat)are favorable for the formation of primary pores and secondary pores in the sedimentary facies dominated dolostone,and therefore become the high quality reservoirs. The results will provide theoretical guidance and technical support for the prediction of the spatial distribution of favorable deep and ultra-deep dolostone reservoir.