A new approach for modeling three-dimensional fractured reservoirs with embedded complex fracture networks

Abstract

In the last decades, the study of fluid flow through discontinuities such as fractures has received significant attention from the petroleum industry owing to the discovery of highly productive naturally fractured reservoirs. Several approaches based on an explicit or implicit representation of fractures have been adopted for modeling fluid migration in fractured rocks. The explicit approach is the most accurate for such a purpose; however, it is computationally expensive. Alternatively, the implicit representation is very attractive because fracture properties, such as stiffness and permeability can be introduced in the model through dual continuum models. Therefore, the modeling of fluid flow through fractured porous media has been performed through conceptual models, while the modelling of more realistic scenarios is still an open question. This paper proposes a new embedded fracture approach for fluid flow in highly fractured porous media. This approach includes the fracture contribution into the continuum element using a condensation technique based on the multi-constrain method. The main advantage of this approach is the guarantee of compatibility between fracture and porous matrix within a standard finite element mesh. Several fractured rock reservoir cells are analyzed to demonstrate the robustness of the proposed approach and its applicability to highly fractured rocks with random fracture orientation. The pore pressure field obtained with the proposed embedded approach is very close to the predictions provided by the explicit approach with zero-thickness interface elements. Despite the simplicity of the method, the results are promising.