In view of the characteristics of high porosity and high permeability in heavy oil reservoirs,together with the high⁃intensity injection⁃production conditions,challenges such as thermal fluid channeling,sudden increase in water cut,and deteriorating development performance have become increasingly prominent in the middle and late stages of steam flooding.Therefore,new technologies are urgently needed to further enhance development efficiency.The variation laws of thermal fluid temperature field and saturation field were investigated via numerical simulation and laboratory simulation experiments,on the basis of which the thermochemical⁃gas alternating flooding technology was studied.The results show that in the middle and late stages of the conversion from cyclic steam stimulation to steam flooding in thin heavy oil reservoirs,thermal communication occurs in some wells within the well group;the expansion radius of the temperature field reaches 100~140 m,and the water cut rises to 74%. According to the analysis of the heating chamber expansion law,the area ratio of the heated zone to the unheated zone in the reservoir is close to 1∶1,and the remaining oil in the unheated zone is abundant but not effectively produced.By optimizing the composite system composed of high⁃temperature reinforced foam and high⁃temperature⁃resistant low⁃viscosity consolidated gel, the plugging efficiency can exceed 97.0%,realizing fluid diversion and enabling the recovery of enriched remaining oil.A process is proposed that utilizes the residual heat in the formation supplemented by hot water,combined with alternate injection of flue gas and other gases.Numerical simulation results indicate that the oil recovery factor can be improved by approximately 2.00%.