Three - Dimensional Three - Phase Numerical Simulation Of Natural Fractured Reservoir

Naturally fractured reservoirs, which contain nearly half of the world oil reserves and are of great economic and strategic value, are found throughout the world. Both description and development of this kind of reservoirs is one of the most challenging problems in reservoir engineering. With the large-scale development of naturally fractured reservoir, it is very important to study the numerical simulation method of such reservoirs theoretically and technically.Based on the review of related literatures, a general mathematical model for naturally.fractured reservoir is established, and a fully implicit three dimensional and three phase numerical model for NFR is created using finite difference method. Finally a simulator is developed using FORTRAN95language. The two most commonly used approaches for NFR simulation, dual porosity/single permeability and dual porosity/dual permeability, are provided in this simulator. The new simulator is verified and tested against the commercial simulator, CMG. Besides, the simulation results of gravity differentiation and solution gas drive process also show that the simulator’s calculation result is reliable. Finally, the impacts of capillary force and injection-production ratio are studied by the examples computation. It is found that the small change of capillary may results in significant variation of production performance. So, it is very important to get the accurate value of capillary force before simulating NFR. Besides, a reasonable injection-production ratio is critical when developing NFR by water flooding, as the study shows that the injected water can channeling along the fracture easily, which results in early watered-out producers and declining yield.