A novel fluid-solid coupling model for the oil-water flow in the natural fractured reservoirs

The mutual coupling effect between the fluid flow and the in situ stress fields cannot be ignored during the development of natural fractured reservoirs (NFRs), such as in the waterflooding process. In this study, a discrete fracture model is proposed to simulate the rock deformation and two-phase flow behaviors of oil and water in the NFR. The numerical solution of the model is achieved via the finite-element method and control-volume finite-element method. The numerical simulator is verified using commercial software, and a perfect agreement is obtained. Finally, sensitivity analysis is conducted on the key parameters in the model, such as fracture parameters, matrix permeability, and injection intensity. Results show that the fluid-solid coupling effect gradually weakens with production time. The degree of the fluid-solid coupling on cumulative oil production becomes smaller as the permeability of the matrix increases. Fracture connectivity controls the velocity and direction of the water flood front. Water injection intensity directly affects the natural fracture opening deformation and well productivity. The research and the numerical results obtained in this paper can provide theoretical guidance for the optimal design of water flooding operations in NFR.

Automated summary

A discrete fracture model was proposed in this study to simulate rock deformation and two-phase flow behaviors in NFR, with sensitivity analysis conducted on key parameters. Results showed that the fluid-solid coupling effect weakened with production time, decreased with increased matrix permeability, fracture connectivity controlled the water flood front, and water injection intensity affected natural fracture opening deformation and well productivity.