Investigation of Waterflooding Performance of Multilayered Reservoir by Pore Scale Network Modelling and Combined Coreflooding

Abstract The heterogeneous property of multilayered reservoir play very important role in the waterflooding performance. At present, it is difficult in characterization of cross-flow and fingering in reservoir scale injection processes and simulating it in laboratory. Although some methods like traditional research methods, experimental physics modeling and numerical simulation of different scales, can obtain some macroscopic insights, they were not suitable to study phenomenon of cross-flow and fingering in multilayered models from micro-mechanism perspective. As a computer stochastic-simulating technology in reservoir physics, pore scale network model has been used in many fields, such as single-phase flow simulation, multi-phase flow simulation, and chemical flooding simulation, etc. A special network model which is suitable for simulation of multilayered models is introduced in this article. In order to describe heterogeneity between layers, framework of the special network model is combining of different small frameworks that represent radii distribution of pores and throats of different layers. Quasi-static flow rule is applied in this paper, which is more comprehensive than static flow rule and faster in simulation computation than dynamic flow rule. Notice that a new dimensionless variable, which is a combination of viscous forces, capillary forces and gravity forces, is introduced in this model to control cross-flow and fingering. Two multilayered physics modeling experiment are conducted in this work. Through CT scanning method, invading front could be identified clearly at different flooding stages. Invading front shapes were almost the same when comparisons with network modeling results. It indicates that the proposed dimensionless variable described microscopic mechanism of cross-flow and fingering phenomenon well.