Flexibility Research of Hot-Water Flooding followed Steam Injection in Heavy Oil Reservoirs

Abstract

Abstract With the accelerating of exploitation, a great number of heavy oil reservoirs or blocks have reached the intermediary and later stage of steam injection development. It is faced with changing the thermal development mode. Aimed at the residual oil of thermal production, this paper studies the alternative development mode after steam injection. Using the physical simulation method, we study the development effect of converting into Hot-water flooding under different temperature and different moment, and investigate the oil displacement efficiency of Water-Alternating-Steam Process (WASP). Then the result of Nitrogen hot-water foam flooding is discussed. Furthermore, it also argues the optimal reservoir rhythm which is suitable to converting into Hot-water flooding, and optimizes the confinement of reservoir thickness and heterogeneity by the method of numerical simulation. The obtained results indicate that Hot-water flooding with 120 °C will obtain a great recovery performance. The best converting moment of Hot-water flooding is when the heavy crude oil recovery was about 22%. In comparison with the Hot-water flooding, the capacity to enhance the sweep efficiency of WASP is more remarkable. Nitrogen hot-water foam flooding could reduce the water cut by 20% above, and enhance the oil recovery by 25% above. Due to the action of gravitational differentiation, a Reverse rhythm reservoir convert into Hot-water flooding will acquire a good result. That reservoir where the thickness is less than 5m, and the permeability coefficient of variation is less than 0.4 could yield a higher oil recovery. These results could play an important guiding significance to switch the thermal development mode. In addition, they can also be used as a tool for the successful design of Hot-water flooding after steam injection to enhance crude oil recovery in heavy oil reservoirs.