Experimental Study of CO2- and Methane- Foam Using Carbonate Core Material at Reservoir Conditions

Abstract

Abstract Foam has been applied to improve sweep during gas injection or for gas shut-off, and also for cleaning of contaminated underground formations. In this paper, foam properties have been evaluated for applications in carbonate material. The emphasis has been to investigate CO2 foam, and therefore, methane and CO2 based foam has been compared. Several foam experiments have been performed at high temperature and high pressure, respectively 100 °C and 277 bars in Limestone outcrop and carbonate reservoir cores. The foams ability to block or reduce mobility of unwanted gas and water is also target of the investigation. The surfactant, C14/16 Alpha Olefin Sulfonate (AOS), ability to generate foam was influenced by the salinity of the injection water. Moderate to strong foam was generated both for CO2 and CH4 foams in limestone core material using 0.5 wt% surfactant concentration at seawater salinity. Mobility reduction factors at end of experiments for the different core floodings were in the range of ~ 13 to 43. The generated foams showed good ability to reduce gas and water production at low pressure gradients. In high saline formation water foam formation failed in limestone outcrop core material. For the carbonate reservoir core material, foam generation was influenced by the injection method. The preferred injection would be co-injection of gas and surfactant solution, but this method failed to generate foam. However, when pregenerated foam was injected, CO2 foam was observed at the outlet end of the reservoir core.