FOR BRODD COMMUNICATION Publication: Deepwater Operations By: Gunn Iren Kleppe
WORKING TITLE: IOR & EOR (full story includes Q&A, fact sheet, etc.) NCS continues to be a world leader in oil recovery. While the global average is about 36 %, the NCS average is now 47 %. Nevertheless, operators on NCS are not satisfied and are aiming even higher. – A recovery factor of 47 % at the end of field life, still means 53 % oil left in the field, says Erik Skjetne, OG21 Leader for Exploration and Increased Recovery (TTA2). At present, there is about 46 % immobile and 54 % mobile oil left in Norwegian fields in production. Mobile oil can be recovered mainly by drilling more wells in each reservoir. Immobile oil, however, cannot be recovered using standard water and gas injection. – It is a different game, he argues. Need for innovation The 90s saw an increase in the recovery factor, and most fields have larger reserves than initially estimated. — On average 68%, he adds. However, the recovery factor has since flattened and new technologies are needed to spur another increase. NCS has been a driver in advanced geo- and reservoir modelling worldwide. New developments include a tighter and faster integration of advanced geo-modelling, 4D seismic reservoir monitoring and dynamic reservoir simulation, where history matching is used to predict future production. Good models are crucial to optimize well location in complex or depleted reservoirs. Still potential – Water injection has given rise to enormous value creation, Skjetne points out. Ekofisk, for example, initially had a 17 % recovery factor without water injection. Today the goal is 50 % and higher. – We know that new technology works. However, many methods that we know work very well onshore, have yet to be implemented offshore, he explains. Enhanced Oil Recovery (EOR) goes beyond standard gas and water injection, typically involving chemicals added to water or gas based methods like CO2 injection. – If the price of oil remains high, there is still a great potential for further improvement. We need new—and more efficient and environmentally friendly—chemicals as well as improved reservoir simulation to reduce uncertainty and justify the high cost of new recovery methods, he concludes.