The continued use of gas injection to improve oil recovery and the prospects for its increased use throughout the world provide impetus to improve sweep efficiency of injected gas. Work is being carried out to improve understanding and the economics of mobility control agents. This paper describes the use of foam to decrease the mobility of gas in coreflooding apparatus at reservoir conditions. Foam behavior and adsorption, two of the mechanisms required to model surfactant requirements, are studied in this project. This study uses a commercial surfactant, nitrogen gas, and reservoir conditions of 10.34 MPa (1500 psi) and 40°C (104°F), and Indiana limestone. Variables are surfactant concentration, flow rate and foam quality.
At a constant gas flow rate, gas mobility slightly decreases with increasing foam quality when below the critical foam quality (fg*) and increases with increasing foam quality above fg*. Increased surfactant concentration leads to the decrease of gas mobility. Comparing coinjected surfactant and gas (CSG) with coinjected water and gas (CWG) shows that the mobility of CSG is an order of magnitude lower than that of CWG. Also, it took more time for CSG to reach steady state compared to CWG, even with a surfactant pad conditioning the core before surfactant and gas were coinjected.