Successful Foam EOR Pilot in a Mature Volatile Oil Reservoir Under Miscible Gas Injection

A successful field trial of foams as gas injection conformance enhancer has been deployed in the Cusiana field in Colombia, South America. This work describes the Front End Loading (FEL) process done to get to the field trial, the field operation itself, and the results obtained so far. The Foam treatment was deployed in the Mirador formation of the Cusiana field, a low porosity quartzarenite with a recovery factor over 50%.The reservoir fluid is a volatile oil developed under an extensive gas reinjection process. The foam treatment was engineered to improve both the gas injection conformance at the wellbore and also the gas sweep efficiency deep into the reservoir. An extensive FEL including chemical product screening, foam stability at reservoir conditions, coreflood experiments, reservoir modelling, and a careful selection of well candidates was executed for this pilot. The treatment was done in a gas injector well in the northern part of the field, where high RF has already been obtained with high levels of gas recycling. The operation was performed using the SAG method. The foaming surfactant was pumped selectively in front of the dominant injection layer and then the well was put back on injection. The results showed a clear and sustained change in GI conformance reducing the injectivity of the treated layer by 60%. Increase in oil rate along with decreases in GOR was also observed in the nearby oil producers two months after the treatment. Results herein presented confirm the viability of foams as an EOR method for the Cusiana field and at least two other fields located in the same basin and exploited under similar conditions.