Profile Control and Displacement Technique with N2 Foam in High-Temperature and High-Salinity Reservoirs of the Tahe Oilfield

To reduce water cut and enhance the oil production of high-temperature and high-salinity (HTHS) reservoirs with edge or bottom water in the Tahe Oilfield, the applicability of profile control and displacement technique with N2 foam was discussed. Through evaluation, HTHS-resistant foaming agents suitable for the HTHS reservoirs in the Tahe Oilfield were selected. Through core displacement tests in the laboratory, the impacts of timing, volume and mode of foam injection on the performance of the proposed technique were investigated. Results show that foaming agent GD-2 demonstrated satisfactory performance under 130℃ and a salinity of 210,000 mg/L with a half-life of 850 seconds after aging for 10 days. In addition, the highest increase in recovery could be achieved by foam flooding with a water cut of 80%-90% in water flooding. The highest increase in recovery was also observed by foam flooding with a volume of injected foam at 0.5 PV. Intermittent injection exhibited better performances than continuous injection and alternative injection of gas and liquid. Field application in TK202H cluster wells demonstrated that all three producers had a higher output and water cut reduction after profile control and displacement with N2 foam. In conclusion, the proposed profile control and displacement technique with N2 foam can effectively reduce water cut and enhance oil production in HTHS reservoirs with edge/bottom water in the Tahe Oilfield.