INVERSE MODELING OF SPONTANEOUS IMBIBITION

Abstract

Reservoirs that contain natural fracture systems, often developed through water injection, comprise a significant portion of the global oil supply. The injected fluid tends to flow preferentially through the fracture network, thereby bypassing the matrix system. Spontaneous imbibition is a crucial recovery technique that relies on capillary pressure-dominated fluid movement. Co-current or counter-current modes can be employed for this technique, depending on boundary conditions. In order to predict and model these phenomena, analytical solutions that incorporate the diffusivity coefficient, which combines relative permeability and capillary pressure curves, are used to describe co-current and counter-current imbibition mechanisms. Perturbation analysis is one method for solving these analytical equations. In-situ water saturation profiles, measured experimentally using CT scanning tests, can be utilized to validate both co-current and counter-current models. The current study uses oil-water and air-water experiments to verify these models. Furthermore, parametric studies were carried out to enhance our understanding of the factors influencing matrix-fracture transfer in porous media. Comparative analysis has been done to identify the main differences and similarities between the two modes of spontaneous imbibition. The input parameters of co-current and counter-current flows are identified and compared with each other using the inverse modeling approach. The understanding of the spontaneous imbibition process can give more details about the fracture-matrix interactions. Analytical models can determine capillary pressure and relative permeability curves for fractured formations and give additional information for experimental studies and analysis of NFRs.