Introduction

The Heavy Oil Recovery Simulation Project was made by Monsieur Mansour KHELIFA an ENSEEIHT student  from Fluid Mechanics department.  During the project, the student was supervised by Monsieur Pierre Horgue a researcher from the IMFT (Institut de Mécanique des Fluides de Toulouse).

 

The aim of this project is the development of a multiphase model in order to simulate the oil recovery process. The oil present in the underground comes from a leakage on an industrial site. The presented model is developed using the OpenFOAM platform.

 

From scientific point of view, this kind of problem is complex, mainly due to the presence of multiphase flow in the domain.

 

First of all we will study the problem in simple cases (one phase flow). After the completion of this work, we will deal with more complex situations (such as two-phase flow...).

 

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During all the project, the geometry considered will be like the geometry presented above : a square in which is introduced a tube corresponding to the producer well.

 

 

 

 

 

 

 

 

Strategy and organization of the project

 

We decided to develop the two phase flow solver by starting with the development and the study of one phase flow solver.

First of all we  will integrated  in the one phase flow solver the permeability as a tensor and the gravity field.

To test this solver we will do several simulation  and by varying one parameter and fixing all the other parameters.

After  accomplishing the work on the one phase flow solver we will develop a two phase solver using a numerical method called IMPES (Implicit Pressure Explicit Saturation).

 

Moreover we will study how to reduce or delay the instabilities created by the method IMPES.

The code will be tested in several simulation without capillary pressure and for fluids of different viscosity and different rate flow of pumping.

 

Finally we will add the capillary pressure and test very simple correlations of capillary pressure.

 

OpenFoam presentation

OpenFoam is a CFD open source code programmed in C++ language. It is mainly aimed to resolve partial derivative equations using finite volume method. OpenFoam is made up by toolboxes that are “easy” to program.
OpenFoam can use his integrated meshing software (blockMesh, snappyHexMesh
) or use meshing converter (Ansys, Salomé, ideas, CFX, Star-CD, Gambit, Gmsh...).

Domain representation

The geometry chosen for the development of the method is a two-dimensional box in which there is one or several wells.

 

The wellbore influence is simply taken into account by adding a source term in the mass conservation equations. In order to have a flexibility in the positions of the wells, a constant, associated which this source term, is defined in the whole domain and must be equal to one where a wellbore is present or zero otherwise.

 

The source term must be negative as in the well the oil is extracted. We took a very simple model of well in order to implement the first simulations. For all the simulations in this project the source term will be equal to the local flow rate.

 

On the Top of the domain we defined a condition of constant pressure (Pref equal to the atmospheric pressure for example).On the rest of domain boundaries we have walls. Then we put a condition of zero velocity on those parts. When we take into account the gravity, the boundary condition on the pressure gradient on the bottom of the domain will be calculated as a function of the gravity field.

                      

Permeability perturbation due to the well introduction

We know that the introduction of a pipe modifies the flow characteristics and change the local permeability. We can define an heterogeneous permeability. However in our case and as a first approach we will focus only on the permeability in the porous media. We will consider that the well introduction will not affect the permeability.