Establishment of a Workflow to Assess Pore Collapse Mechanics During a Series of Loading and Unloading Using Micro-CT Scan and Rock Mechanics Testing

Abstract

Characterization of the reservoir rock elastic and plastic behavior is essential to set a series of guidelines for reservoir management, especially during gas storage cyclicity. The reservoir rock is subjected to loading during injection and unloading during depletion. These procedures lead to increases and decreases in the magnitude of the effective stresses in the poroelastic media. The guidelines for the reservoir development should be set to operate the field within the elastic limit of the formation to ensure the undamaged permeability of continuous fluid flow in and out of the reservoir. Based on these factors, there is a need to accurately measure the dynamic permeability and porosity by characterizing the pore space and pore throat collapse for the current and future injection and depletion operations. This invention will achieve this measurement through a series of alternating measures between a three-dimensional (3D) X-ray computed tomography (CT) imaging and triaxial testing. These accurate and actual measurements mainly come from core plugs testing. The process starts (T1) by scanning the core plugs with high-resolution imaging technology to map pore space and pore throat. The samples will be subjected to the first step of loading and unloading during Thick Wall Cylinder (TWC) test using different axial and confining pressure. The samples will be imaged and then mapped in the pore space and pore throat at a time (T2), and these processes will continue for ten cycles of loading and unloading. The results will be interpreted and extrapolated to match the number of injection and depletion scenarios. The fluid flow will be numerically simulated at the pore scale using direct flow modeling within the pore space with the Navier-Stokes-Brinkman equation to evaluate changes in permeability and porosity. Using these novel integrated processes presented by this invention, injection and depletion guidelines will be set for future operations; this methodology also can be used for oil recovery to ensure safe operations within an elastic limit to avoid permeability damage that will lead to safe, effective, and economical operational scenarios.