泥质地层中饱和度指数的确定

Determination of saturation exponent in shaly formation

Archie公式是测井计算储层含水饱和度的重要依据之一,但它只适应用于较纯的砂岩储层。在泥质地层中,电阻率指数的对数与含水饱和度的对数之间是非线性关系,即饱和度指数随电阻率指数的变化而变化,而且不同孔隙结构、泥质条件下其变化不同。根据毛管理论、统计学原理、积分原理和体积模型法,推导出泥质地层饱和度指数与泥质含量、孔隙结构参数及电阻率指数的关系,并确定出泥质地层不同条件下的饱和度指数,才能使利用Archie公式计算的储层含水饱和度具有较高的准确性。

Archie formula is important for calculating water saturation of the reservoir, but it is only applicable to pure sandstone reservoirs. In the shaly formation,it is nonlinear relationship between the logarithm of the resistivity index and the logarithm of water saturation. The saturation exponent changes with resistivity index, with different changes under different pore structure and shale conditions. According to capillary tube theory ,statistical theory ,integration principle and volume model method, the relationship among saturation exponent, shale content, the parameters of pore structure and the resistivity index in shaly formation is derived, and the saturation exponent of shaly formation under different condition is determined.