Method and application of accurate determination of nano-pore adsorption thickness in shale oil reservoir

Abstract At present, there is no method to accurately characterize the liquid film thickness of shale nanopores with different mineral compositions. This article describes the wetting modification of a 500nm homogeneous quartz model, measures the liquid film thickness under different pressure gradients, and establishes experimental expressions. Based on the experimental results, a prediction method for the thickness of the nanopore boundary layer and a theoretical model for the thickness of the adsorption layer were determined and applied to the Da'anzhai shale in the Sichuan Basin. The results indicate that the established experimental method can determine the thickness of the adsorption layer within the shale nanopore system; The adsorption characteristics of Da'anzhai shale suggest that the adsorption layer of Da'anzhai shale is relatively thick with high clay content, low feldspar and calcite content; The movable lower limit(critical pore throat size for fluid flow) of five different lithofacies combinations in Da'anzhai is determined to be between 37-76nm.And it is of great significance for improving the accuracy of shale oil/gas geological reserves (GIP) and recoverable reserves (EUR) prediction.