Influencing Factors on Resistivity Anisotropy Measurement of Bedded Shale Plug Samples
Resistivity plays a critical role in the saturation evaluation of various oil and gas reservoirs.However,the resistivity of bedded shale exhibits strong anisotropy.To investigate the influence of various factors on the anisotropic resistivity measurement of bedded shale plug samples using the dual-electrode method,numerical simulations were conducted.The resistivity ratio between samples with different bedding angles and that with a 0° bedding angle was defined as the anisotropy coefficient.The simulation results indicate that the anisotropy coefficient is positively correlated with the cosine value of the bedding angle.When the bedding plane is inclined to the long axis of the sample,the anisotropy coefficient increased with larger differences in thickness or conductivity between clay and matrix laminae.Sample length affected the contact relationship between the bedding plane and the top and bottom faces of the sample.When the bedding plane passed through the top and bottom faces of the sample,more current is focused on the high-conductivity laminae,thereby weakening the contribution of high-resistivity laminae to the sample's resistivity.A mathematical model was proposed to describe the relationship between the anisotropy coefficient and the measurement angle,which could be applied to the anisotropy correction of resistivity measurements in bedded shale and other bedded formations,facilitating the quantitative evaluation of unconventional oil and gas resources.The research findings have significant reference values for directing resistivity anisotropy experiments on bedded formations and the correction of resistivity logging data.
万方数据
维普
