Transport of polymer particles in a oil-water flow in porous media: enhancing oil recovery

TL;DR

This paper develops a core-scale model for polymer particle transport in oil-water flow within porous media, explaining enhanced oil recovery through microscopic diversion and clogging effects observed experimentally.

Contribution

It introduces a novel two-phase flow model incorporating polymer transport and dynamic permeability changes to explain enhanced oil recovery mechanisms.

Findings

Qualitative agreement with experimental results

Microscopic diversion causes flow redistribution

Permeability alteration impacts oil mobilization

Abstract

We study a heuristic, core-scale model for the transport of polymer particles in a two phase (oil and water) porous medium. We are motivated by recent experimental observations which report increased oil recovery when polymers are injected after the initial waterflood. The recovery mechanism is believed to be microscopic diversion of the flow, where injected particles can accumulate in narrow pore throats and clog it, in a process known as a log-jamming effect. The blockage of the narrow pore channels lead to a microscopic diversion of the water flow, causing a redistribution of the local pressure, which again can lead to the mobilization of trapped oil, enhancing its recovery. Our objective herein is to develop a core-scale model that is consistent with the observed production profiles. We show that previously obtained experimental results can be qualitatively explained by a simple two-phase flow model with an additional transport equation for the polymer particles. A key aspect of the formulation is that the microscopic heterogeneity of the rock and a dynamic altering of the permeability must be taken into account in the rate equations.