Experimental research on dynamic imbibition of fractured heavy oil reservoir under different temperatures

Fractured reservoirs contain a large fraction of the world supply of oil and imbibition is one of the dominant recovery mechanisms. For fractured reservoirs containing heavy oils or tars, oil viscosity is high and it is hard to get a good development effect at reservoir temperature. However, if thermal methods are adopted, the oil viscosity will decrease sharply as temperature goes on and the oil recovery will increase on the contrary due to capillary imbibition. In this paper, fracture is created by wrapping the core with a steel wire mesh. Before flooding, cores are let to stand at the experimental temperature to eliminate the effect of thermal expansion on oil recovery. Considering that oil volume recovered is very small, a high precision electronic balance is used to weigh the oil and then calculate the oil volume. Different factors including contact area, matrix permeability, oil viscosity, water injection rate, temperature of the injected fluid and wettability of the core are all investigated. Results of this work should be helpful for the better understanding of the capillary imbibition in the development of fractured heavy oil reservoir. © 2013 The Author(s).