塔中北斜坡柯坪塔格组沉积相分析

Analysis on Sedimentary Facies of Kepingtage Formation of Silurian in the northern slope of Tazhong Area

志留系柯坪塔格组是塔中北斜坡油气勘探重点层位之一。对其沉积相类型及沉积特征的认识长期以来一直存在分歧。结合前人研究成果,据钻井、测井及岩心资料对柯坪塔格组沉积相进行详细研究。结果表明,塔中北坡主要发育潮坪、滨岸-陆棚沉积体系,局部发育辫状河三角洲沉积,主要发育滨岸砂体、陆棚砂体、潮道、砂坪和三角洲水下分流河道等有利储集砂体。在对沉积相深入分析的基础上,建立了柯坪塔格组沉积模式,滨岸砂体储集性优于潮坪相砂体。

There is a lot of debate among different scholars on the type and characteristic of sedimentary facies in reservoir of Kepingtage Formation of Silurian which is an important oil-producing district in the northern slope of Tazhong Area. Based on drilling, well logs and core data the sedimentary facies are studied in detail with previous study. The con- gclusions show that Kepingtage Formation deposited tidal flat, shoreline-neritic sedimentary system, and braided-river delta. The types of sandbody are shore sand, shelf sand, tidal channel, sand fiat, underwater distributary channel. Based on the deliberate analysis of sedimentary facies, the authors set up the sedimentary model. The physical property of the shore sandstones is better than that of the sandstone of tidal fiat. The sedimentary system is the geologic foundation for forming the lithologic trap. The establishmentof the sedimentary facies type and sedimentary model provide the basis for further reservoir prediction in the area.