Study on technology of profile control and oil displacement with gelled foam for high temperature and high salinity reservoir of Tahe Oilfield

In view of enhanced oil recovery of high temperature, high salinity and significantly heterogeneous reservoir in Tahe Oilfield, research on technology of profile control and oil displacement with gelled foam for high temperature and high salinity reservoir was carried out in this paper. Through Ross-Miles and GSC strength code method, the heat-resistance and salt-tolerance foaming agent and gelled foam stabilizing system was optimized, and the composition and formula of gelled foam profile control and oil displacement system with adjustable strength is determined: 0.4%-0.5% HTSP polymer+0.09%-0.16% RELMNE crosslinker+0.2%-0.3% HTS-1 foaming agent. The synthetic value of foam is over two times that of common foam. The adaptability of gelled foam system to different strata and its capacity to enhance oil recovery are evaluated through physical simulation experiment. The results show that gelled foam has great selective adaptability to stratum, for permeability ranging from 0.6μm2 to 3μm2, the residual resistance factor increases with increase of formation permeability, leading to obvious profile control effect. Compared with common foam, simple gas flooding and water flooding, the gelled foam system could activate low permeability reservoir effectively and enhance oil recovery up to 26.93%. Incremental oil recovery obtained through gelled foam is 2.3 times that of common foam, 6.2 times that of gas flooding and 14.7% higher than that of common water flooding. Gelled foam has a wide application prospect, which provides a new method for further enhanced oil recovery in Tahe high temperature and high salinity reservoirs.