Study and Optimization of the First Horizontal Well Steamflooding Pilot for Offshore Oilfield

Abstract

Abstract The steam and flue gas co-injection technology is proposed and applied to NN Oilfield whose oil viscosity ranges from 413 to 741mPa.s for field pilot since 2008. With increase of the stimulation cycles, the gas channeling problem had bad influence on the production performance, and the production rate declined rapidly. To further improve the oil recovery, research is carried out for optimization of the replacement production method. First, the reasons for gas breakthrough are analyzed. Potential methods are all analyzed and compared by reservoir simulation and physical experiments. By considering the equipment capacity, platform limitations and economics, the optimized production method is determined. For the NN Oilfield developed with horizontal wells, the steamflooding is a good way of further exploitation after steam and flue gas co-injection. The key injection and production parameters are all optimized with the results of steam injection rate 300 m3/d, production-injection ratio 1.4, and downhole steam quality 0.4-0.6. To further improve the field performance, the nitrogen foam could be injected to mitigate the steam breakthrough. Simulation study shows that it is significantly effective for the improvement of oil production rate. Detailed project design has been completed and illustrated in detail. Steam flooding would be an effective replacement technology after huff and puff for further enhancing oil recovery of offshore heavy oilfields.