Improving matrix recovery using chemicals and thermal methods in fractured heavy-oil reservoirs

To increase the effectiveness of heavy-oil recovery from matrix by capillary imbibition, surfactant and polymer solutions or hot water can be used as an aqueous phase. The effect of them on the matrix fracture transfer performance was investigated in this article. The observations and analysis of the laboratory scale experimentation on these three methods were reported. Experiments were conducted on water-wet (Berea sandstone) and oil-wet samples (Indiana limestone) using engine oil and heavy crude oil. Different boundary conditions were created so that both co and counter-current type matrix-fracture transfers took place. Performances were compared in terms of ultimate recovery, recovery rate and the cost of the process. It was observed that all three aqueous phases yielded higher and faster recovery compared to waterflooding with some exceptions. This difference was more prominent for counter-current capillary imbibition. The exceptional cases were scrutinized and the possible reasons were discussed. Based on these observations, suggestions were made for the most suitable aqueous phase yielding the best performance for different rock wettabilities and oil-types.