Non-thermal heavy oil recovery methods are important, because many heavy oilreservoirs are unsuited for thermal methods. Emulsion flooding is one of themore promising non-thermal methods. In this experimental research, the effectof injection rate was examined for a Lloydminster crude and for a Morichalcrude oil. Two different emulsions were used, one being oil-in-water and theother one water-inoil-type.
Displacement tests were carried out at the reservoir temperature in eachcase. In all tests, the core initially contained irreducible water. Emulsionslugs, 3 and 12% pore volume, were driven by brine.
It was found that oil recovery was sensitive to injection rate, insofar asthe recovery varied from 67% to 57% in the case of the Morichal crude, and 59%to 51% in the case of the Lloydmlnster crude, depending on the rate. The floodrate would determine the extent of mobility ratio variation, which in turn, depends on the drop size, the type and rheology of the emulsion. Themechanistic features of the process are discussed.
Considering the large resources of moderately heavy oils that cannot beexploited by thermal methods, it is important that viable non-thermal recoverymethods be developed. At present, at least 10 billion m3 of oils inthe 100–2000 mPa.s viscosity range occur in reservoirs in Canada, which are toothin, too deep, or marginal for other reasons, and thus unsuitable for theapplication of thermal methods, particularly steam injection. The non-thermalmethods tested In the laboratory and in the field include chemical floods, ofwhich alkaline flooding has received considerable attention. Based uponprevious work, emulsion floods may be more effective than alkaline floods. Theemulsions formed in situ in the latter case must contend with the rock.alkalireactions and the concomitant loss.
