Oil Displacement Experiments in Heterogeneous Cores: Analysis of Recovery Mechanisms

Abstract

ABSTRACT In a previous paper, we reported on an extensive series of single phase stable displacement experiments in a heterogeneous core system consisting of a cylinder of sandstone with a central core removed and filled with high permeability unconsolidated material; this is referred to as a cored core [1]. These experiments were designed to show some of the main viscous cross flow mechanisms which occur in processes such as polymer flooding in stratified systems. In this work, we extend these results in the cored core system by reporting on a series of oil displacement experiments. The objective of this work is to establish how the recovery mechanisms observed in the single phase experiments in the dual permeability core are modified when there is two phase flow with changing mobility in the aqueous phase. Qualitatively, the viscous cross flow recovery mechanisms seen in the single phase experiments, are also observed here although they are modified to some extent by two phase (relative permeability) effects. As in our previous work, numerical simulation is used in order to interpret and model the main experimental observations. Good agreement is obtained between experiment and theory in that observed cumulative oil curves, watercuts, layer flow rates and tracer profiles are well reproduced by the calculations. The simulation results lead to a clear interpretation of the two phase displacement experiments in terms of effects associated with relative permeabilities and the presence of the glycerol viscosifier.