Matrix acidization in fractured porous media with the continuum fracture model and thermal Darcy-Brinkman-Forchheimer framework

Abstract

The numerical simulation of matrix acidization in fractured porous media is continuous work in the reservoir simulation community. However, existing works mainly depend on two kinds of models to describe fractured porous media: the discrete fracture-matrix (DFM) model and the continuum fracture (CF) model. In addition, most of the works use Darcy's equation to describe the flows. The DFM model can accurately describe the fracture and the flow in the fracture at the cost of the complexity of the simulation framework. On the other hand, the CF model treats the fracture and the matrix uniformly, which reduces the complexity of the simulation framework, but the accuracy of the results is not as good as that of the DFM model. In summary, the challenge of this area is that the accuracy of the results cannot be guaranteed by a sufficiently simple model. The Darcy-Brinkman-Forchheimer (DBF) framework was originally developed to handle an issue in matrix acidization simulation, i.e., the flows in the high-porosity zones cannot be well described by Darcy's law. Considering the similarity of the fracture and the high-porosity zones, it is anticipated that the proposed DBF framework can also describe the flows in the fracture well., i.e., the accuracy of the results guaranteed by the DFM model can also be guaranteed by the DBF framework. Compared with the DFM model, the DBF framework is much simpler. Moreover, the DBF framework can be naturally integrated with the CF model. Thus, this work leverages the CF model and the DBF framework to simulate matrix acidization in fractured porous media, by which accurate results can be achieved with a simple simulation framework. The simulation results in this work are compared with those of Khoei's work, by which the reasonability of this work is demonstrated. After that, the thermal DBF framework, which is an expansion of the DBF framework, is leveraged to investigate matrix acidization in fractured porous media under different thermal conditions, and many helpful conclusions that benefit realistic operations are drawn. For example, the fracture orientation can have different effects on matrix acidization under different temperature conditions.