A New General Flow Model for Well Test Analysis for Fluids Used in Enhanced Oil Recovery Projects

Abstract

Abstract Fluids used in Enhanced Oil Recovery (EOR) projects, such as polymers, micellars solutions and surfactants are classified as non-Newtonian fluids, due to their viscosity behavior. The measuring and analysis of pressure data during injection of non-Newtonian fluids and during fall-off periods has become popular. However, the lack of appropriate tools for its interpretation might yield incorrect results when characterizing parameters are computed, such as flowing geometry around wellbore, formation permeability, skin factor at wellbore, injected fluid consistency index, etc. This paper presents a new general flow model for non-Newtonian fluids governed by a partial differential equation. Analytical solutions for such model are also presented. The model and its solutions are suitable to identify three of the most common flow geometries (linear, radial and spherical flow), when a displacement agent is flowing within the porous media in EOR projects. Due to its behavior, this model is appropriate when extra heavy oil is flowing in the reservoir. A better understanding and representation of the fluid flowing into the reservoir can improve the monitoring and execution of EOR projects and reservoir exploitation schemes. Linear, Radial and Spherical diffusivity equations for Newtonian fluids are particular cases of the new model. For different flow geometries, graphs of the pressure and its derivative behavior against time are presented. A method for determining fluid consistency index and flow geometry is presented. A synthetic example that describes the application of the new model is also shown.