Characterization of two-phase flow in porous media using global mobility

Abstract

Abstract Proper characterization of multi-phase flow in porous media is of significant importance in selecting and optimizing the performance of a given oil reservoir. The main factors influencing the characterization of multi-phase flow in porous media include: microscopic pore structure, movable fluid saturation, nonlinear seepage characteristics and clay minerals composition, and etc. However, it is very difficult to quantitatively study the multi-phase flow process in porous media, because there is no clear relationship between the oil production rate and the physical parameters of oil reservoir, particularly in low permeability reservoirs. Furthermore, on-going research activities has led to the discovery that it has been a challenge to tell why two oil reservoirs with the same degree of permeability (i.e. low permeability) have far different production performances. In an attempt to comprehend this challenge, a concept of global mobility by Li and Horne (2005, 2006) derived from the Li-Horne model was proved to be a new approach for evaluating the seepage capacity in imbibition system, because it can unify oil and water phase mobility into one model and take many static and dynamic physical parameters into accounts. In this paper, the global mobility concept is applied and verified to characterize the mobility of a multi-phase flow and evaluate the production performance from core to field scale. Comparisons between the global mobility concept and other characterization methods were conducted based on various flooding experiments and field data tests from rock/oil/water systems and rock/oil/polymer systems with different porosities and permeabilities. The results showed that there is a linear relationship between the global mobility and the production performance which is better than the other methods, and the application range of the global mobility was extended. In addition, a convenient and empirical approach was proposed to obtain the global mobility with relative permeability data. Its feasibility has been preliminarily proved through five case studies, and the demonstration is that the global mobility could be an effective parameter to characterize a two-phase flow in porous media and evaluate the production performance for field application.