The paper presents new experimental results from laboratory studies on the use of gas-blocking foams for controlling gas influx into production wells. Foam performance is measured using the well-qualified gas-blockage test procedure at the conditions of four reservoirs where pilot testing of foams is currently planned or on-going. New foam formulations are described where polymer is incorporated into the foaming-agent formulation. For one reservoir, cross-linking chemicals have also been included, allowing comparison of conventional foams stabilised only by surfactant, polymer-fortified foams, and gelled foams.
The results show that strongly improved gas-blockage performance may be obtained by addition of polymer to the foaming-agent solution. In the most favorable cases, foams of essentially no gas-blocking ability can be transformed to very efficient gas-blocking agents by adding polymer. However, in some (repeated) experiments, polymer addition did not result in a better gas-blocking foam, and concentration effects are observed so that adding too much polymer can give sharply reduced foam efficiency. Gel foams also are not necessarily superior to polymer foams as gas-blocking agents.
It is concluded that polymer-enhanced foams are of great potential value for gas influx control, but that more knowledge of surfactant/polymer interaction in the thin film network that constitutes the foam is required in order to predict the effects of adding polymer to gas-blocking foam formulations.