基于扩散双电层理论的低对比度油层判别新方法

New Method for Discrimination of Low Contrast Reservoir Based on Diffusion Double Layer Theory

对于渤海油田大量低幅度油藏背景下的中、高孔隙度渗透率低对比度油层,依靠现有自然电位等曲线建立的储层流体识别方法对判断界面附近的油、水层仍存在较大不确定性。从黏土矿物与周围溶液的扩散双电层理论着手,利用黏土水束缚水饱和度与基于电法测井计算得到的可动水饱和度进行叠合,当基于电法测井计算含水饱和度大于扩散双电层计算的黏土水饱和度时,表明地层存在可动水;反之为油层。该方法经实际资料应用证实能够较好判别界面附近的储层流体性质,可为其他类似储层流体识别提供技术支持。

In recent years,with the developing of exploration and development in the Bohai oil field,more and more attention has been placed into the low contrast reservoir.However,the existing method of reservoir fluid identification based on the spontaneous potential and other logging responses has uncertainty in identifying the fluid types near the interface.Therefore,this paper proposed a new method to identify fluids based on the research on the clay minerals and the theory of diffusion double electric layer in solution around it.The principle of this method is to compare the difference between the clay bound water saturation which calculated from diffusion double electric layer theory and the movable water saturation which calculated from the resistivity.When movable water saturation is greater than the clay bound water saturation,it indicates moving water in the formation,otherwise,is oil.This method has been confirmed by practical data that can be used to identify fluid types near the interface and can provide technical support for other similar reservoir to identify fluid types.