A Multicomponent Isothermal System for Efficient Reservoir Simulation

Abstract

Abstract A new model has been developed specifically to study very large, heterogeneous oil and gas reservoirs. By using unique approaches to the simulation of fluid properties and dual porosity/permeability systems, the model is able to accurately simulate complex reservoir flow performance that was previously difficult or not feasible to model. Descriptions of the fluid flow characteristics of the model are included in the Appendix. Potential applications to several real field simulation problems are discussed to show the advantages of the model as compared to more traditional approaches. Additionally, several actual simulations of hypothetical reservoirs are shown and the results are compared with both standard single porosity and dual porosity black oil models currently available. The enhanced representation of the physical system compared to classical black oil models is achieved in a way which is efficient in the use of both the memory and processor resources of the computer, whilst the modular nature of the simulator, coupled with advanced programming and documentation standards, will facilitate its further development and maintenance. Introduction Much of the oil and gas being produced today comes from extremely complex reservoirs. These reservoirs are generally characterized by being very large and highly heterogeneous. Many exhibit significant spatial variations in fluid properties. Most are also fractured to some extent. The basic black oil reservoir simulation models will not rigourously account for the problems encountered in studying these complex reservoirs. Compositional simulators will accurately model fluid property changes but, due to their complexity, are poorly suited to the study of very large fields or secondary porosity or permeability systems. Those compositional fracture simulators developed in the past are rarely applicable to more than single cell studies of mass transfer between fluids in a fracture and am elemental volume of matrix rock. All fracture simulators seem in the literature tend to be too simplistic in approach to be generally applicable to the study of the many types of secondary porosity/permeability systems known to exist. Additionally, most of the models developed are not suited for use in full field model studies that might require many thousands of grid cells.