塔里木盆地塔中低凸起中古43井区碳酸盐岩油气属性分布特征及成藏模式

Oil and Gas Attribute Distribution and Hydrocarbon Accumulation Model of Carbonate Rocks at Well ZG-43 Area in Tazhong Lower Arch,Tarim Basin

塔中地区中古44和中古10两条走滑断裂切割了塔中低凸起中古43井区,它们对油气输导具有控制意义。油气从中—下寒武统沿两条走滑断裂向上运移后,在下奥陶统鹰山组内向两侧输导,呈"T"字形的油气充注方式。从断裂向两侧,V/Ni值呈减小趋势,原油密度、黏度、含硫量和含蜡量等物性参数,距离断裂由近到远,均表现为逐渐变大的趋势,这些都证明油气是由走滑断裂向两侧运移的。水、油、气井的目的层海拔分别为-4 700 m以下、约-4 600～-4 500 m和-4 500 m以上;出油气层位在海拔-4500 m以上的井,平均气油比较高,在海拔-4 500 m以下的井,平均气油比较低。研究井区油气开发的连通半径平均约600 m,小于油气成藏的连通半径。在开发和成藏两种时间尺度下隔挡层的物性上限有着显著差别。

Two strike-slip faults,Fault ZG-44 and Fault ZG-10,which cut Well ZG-43 Area in Tazhong Lower Arch are significant to control of hydrocarbon draining.Hydrocarbon migrates upward along these two strike-slip faults from Middle-Lower Cambrian rocks and transport as a T-shaped filling way by both sides within Lower Ordovician Yingshan carbonate reservoir.As from the faults away to their lateral sides,the V/Ni ratios show a decreasing trend and the physical properties of hydrocarbon such as the crude oil density,viscosity,sulfur content and wax content show a progressively increasing trend with increasing the distance to the faults,which can proves migration of the hydrocarbon from the strike-slip faults to their both lateral sides.According to the data from water,oil and gas wells,the altitudes of water,oil and gas beds are below-4700m,-4500^-4600m and above-4500m respectively.The average gas/oil ratio is relatively high（4136m3/m3） in the wells of oil and gas horizon altitude above-4500m,and the ratio is relatively low（794m3/m3） in the wells of oil and gas horizon altitude below-4500m.Therefore,the oil,gas and water are in normal differentiation on the whole.The average connectivity radius of oil and gas exploitation to other wells is about 600m in Well ZG-43 area.As it is less than the radius,significant differences may exist in the upper limit of the barrier layer′s physical properties in time scales of both hydrocarbon accumulation and exploitation.