塔里木盆地北部“层控”与“断控”型油藏特征——以塔河油田奥陶系油藏为例

Geological characteristics of ‘strata-bound’ and ‘fault-controlled’ reservoirs in the northern Tarim Basin:taking the Ordovician reservoirs in the Tahe Oil Field as an example

基于高精度三维地震资料,尤其是大量的实钻井资料和生产动态数据,对塔里木盆地北部地区海相碳酸盐岩油藏特征进行了系统的对比研究。塔北地区碳酸盐岩缝洞型油藏可划分为以风化壳控制为主的喀斯特油藏和以溶蚀走滑断裂带控制的断溶体油藏2大类。前者发育在塔北中—上奥陶统地层剥蚀区,即古潜山风化壳,可进一步细划为"岩溶残丘型油藏"、"岩溶古河道型油藏"2个亚类,油藏宏观上具有"垂向叠合连片、呈准层状分布"的特征,表现为储集空间变化大、孔洞缝共存、油藏单元相对连片、油水关系复杂等特点。后者则位于南部中—上奥陶统地层覆盖区,主要受控于不同级别溶蚀走滑断裂带控制的断溶体油藏,具有"沿断裂带分段成藏、纵向穿层、空间断续分布"的特点。该类油藏是自然界存在的新类型,有其独特的油藏特征,是我国深层碳酸盐岩油气勘探开发的新类型、新目标。

The marine facies carbonate reservoirs in the northern Tarim Basin were studied using high-resolution3 D seismic data,as well as a large amount of actual drilling data and dynamic production data. The carbonate fractured-and-vuggy reservoirs in the study area were distinguished into two types： strata-bound karst reservoir and fault-controlled karstic-fault reservoir. The former was developed in the buried hill of the paleokarst system in the northern Tarim Basin,which can be further divided into two subtypes： residual hill type and paleo-channel type. Reservoirs are characterized by ＂vertically superimposed and quasi-stratified distribution＂on the macroscopic scale,and feature large changes in reservoir space,coexistence of caves,pores and fractures,relatively contiguous reservoir units,and complex oil-water relationships. The karstic-fault reservoir mainly developed in the covered area of Middle-Upper Ordovician,which is controlled by different ordered strike slip faults and related dissolutions. The karstic-fault reservoir is a special type of oil and gas reservoir existing in nature. It has unique hydrocarbon accumulation characteristics,such as different sections of accumulation along fault belt,across different strata vertically and discontinued distribution and so on. The karstic-fault reservoir is a new trap type and a new target in deep carbonate oil and gas exploration and development.