利用等效电路模型研究泥质砂岩复电阻率频散特性

On the Frequency Dispersion Characteristics of Complex Resistivity in Shaly Sandstone Based on Equivalent Circuit Model

基于泥质砂岩孔隙中离子浓差极化和双电层形变效应,考虑到谐变电流场在泥质砂岩孔隙中引起的离子流和电流的波动特性,依据串联毛细管模型建立了描述泥质砂岩复电阻率的等效电路模型;给出了时间域激发极化电位、时间特性与复电阻率的等效电路模型每个电子元件参数之间的相互换算关系,将等效电路模型电子元件参数与泥质砂岩储渗参数和饱和溶液浓度、阳离子交换量联系起来,定量计算了储层岩石储渗参数和饱和溶液浓度、阳离子交换量等因素对含水泥质砂岩复电阻率频散特性的影响。

For a long time, it is difficult to explain and describe mathematically the microscopic mechanism of complex resistivity in shaly sandstone. Based on ion concentration difference polarization and the deformation effect of electrical double-layer in shaly sandstone and the fluctuantion of ion current and electric current in shaly sandstone caused by harmonic variable current field, we created an equivalent circuit model to describe complex resistivity of shaly sand according to the series of capillary model, and provided the conversion relations between induced polarization potential, time characteristic and electronic component parameter of equivalent circuit model. The influence of concentration of saturated solution, cation exchange capacity and the microscopic parameter of pore structure on the dispersion character of complex resistivity of water bearing shaly sands is quantitatively computed.