Well Injection Tests Of Non-Newtonian Fluids
Authors: Moffitt Paul D. , Menzie Donald E. 
Published: December 2007

In this study, the flow behavior of polymer solutions and micellar solutions in the reservoir was analyzed using the steady state radial flow test (Hall plot). Injectivity data from three tertiary recovery field tests was used to obtain the Hall plots. These field tests are micellar-polymer floods and include the Bradford Field test in Pennsylvania, the North Burbank Unit test in Oklahoma, and the El Dorado Field test in Kansas. The Hall plots for the micellar-polymer floods were then compared to the Hall plot for water. This was to determine the effect of non-Newtonian rheological behavior on the flow of the of the micellar and polymer solutions in the formation.

Since the slope of the Hall plot is proportional to the reciprocal of the mobility, the proportional to the reciprocal of the mobility, the Hall plot is a function not only of the viscosity of the injected fluid, but also depends on the effective permeability to the injected fluid. Therefore, the Hall plot was used to determine if near-wellbore plugging had occurred, if the fluid had behaved as a non-Newtonian fluid, if the effective permeability to the injected fluid had increased due to increased miscibility, or if the permeability had been reduced due to the flow of the polymer solution.

Introduction

Micellar solution flooding followed by polymer flooding for mobility control is presently being evaluated as a tertiary recovery process. Both micellar solution flooding and polymer flooding have been extensively studied in the laboratory, but these processes are complex and their behavior under field conditions may differ from that observed in the laboratory. This is due to the fact that both processes are affected by parameters that cannot be controlled under field conditions.

The objective of micellar solution-polymer flooding is 100 percent displacement efficiency, with high areal and vertical sweep efficiencies. A slug of micellar solution is injected first to displace the reservoir oil. Then a mobility buffer consisting of polymer dissolved in water is injected to protect the micellar solution slug from water invasion. Finally, drive water is injected to propel the micellar solution slug and mobility buffer through the reservoir.

The objective of this study was to investigate the injection well behavior of micellar solutions and polymer solutions. This was done using the Hall plot to compare the reservoir flow behavior of water with the flow behavior of polymer solutions and micellar solutions. The flow behavior of water, a Newtonian fluid, varies from that of polymer solution, a non-Newtonian fluid, due to the difference in their rheological behavior and to the permeability reduction effect of the polymer solution. The flow behavior of micellar solution differs from that of water depending upon its rheological behavior and the effectiveness of the micellar solution in increasing the effective permeability of the porous media to the injected fluids.

THE HALL PLOT

The steady state radial flow plot (Hall plot) was used in this study to analyze the injection well behavior of micellar solutions and polymer solutions. In the Hall plot, the summation of the surface or bottom-hole pressure times time is plotted versus the cumulative fluid injected on coordinate paper. The summation of the effective pressure drop, paper. The summation of the effective pressure drop, Sigma(Pwh × delta t), is analogous to a driving force, and the cumulative fluid injected, Wi, is analogous to a flux. Consequently, the slope of the Hall plot represents a resistivity, the resistance of the fluid to flow through the formation per unit volume of fluid injected. The derivation n of this well test analysis method is given by Hall.