Micro-CT Analysis of Fractures and Permeability Changes in Low-Permeability Rocks After True Triaxial Loading

Abstract

This article presents the results of complex studies of changes in the internal structure and evolution of filtration properties of rocks in the Astrakhan gas-condensate field after physical modeling the implementation of the method of directional unloading of the reservoir. The experiments were carried out on the Triaxial Independent Load Test System of the Institute for Problems in Mechanics of the Russian Academy of Sciences. Scan of one of the samples on a high resolution computed tomography scanner CT-MINI was performed. A digital model of the internal structure of the rock was obtained. Different methods of estimating the finite permeability of a sample using numerical simulation of filtration flows in a rock structure obtained from CT scanning are reviewed and compared. Filtration flow velocity fields and sample permeability values were calculated. It is shown that the use of different approaches to permeability modeling based on scan results can lead to significantly different results. Research results allows to conclude that the method of directional unloading of reservoir can be successfully applied to the rocks of Astrakhan gas condensate field, allowing to significantly improve the filtration properties of rocks in the vicinity of a well.