Investigation of filtration and fracture processes in reservoir rocks of underground gas storage facilities using digital analysis of computed tomography data

In this paper, we investigated changes in the filtration properties and internal structure of underground gas storage (UGS) reservoir rocks caused by the impact of an irregular stress field during the implementation of the bottomhole zone permeability increase method - the directional unloading method. The research was conducted with the use of a ProCon X-Ray CT-MINI high-resolution scanner of the Institute for Problems in Mechanics RAS. Multiscale scans of UGS samples with a developed system of macrocracks formed after geomechanical modeling of the process of implementation of the directional unloading method were carried out. 3D structures of the rock interior were obtained, on the basis of which the numerical simulation of the pore and fracture filtration processes was carried out, the granulometric analysis of the matrix and fracture products was performed, and the changes in filtration properties were assessed. The results of the research confirm the effectiveness of the directional unloading method for the conditions of the studied field, allow for the selection of downhole equipment to solve the problems of sand production, and are also intended to extend the existing approaches to the nondestructive analysis of core material of UGS formations and can be used to create and refine the operational model of the UGS.