RECOVERY OF BITUMEN OR HEAVY OIL IN SITU BY INJECTION OF HOT WATER OR LOW QUALITY STEAM PLUS CAUSTIC AND CARBON DIOXIDE

摘要

ABSTRACTLaboratory coreflood experiments were conducted onAthabasca oil sands using hot water and caustic or carbondioxide. Production temperatures were maintained at150°C or lower and at an injection pressure of 3.55 MPa(500 psi). The objective of the experiments was todetermine the conditions under which oil-in-water (O ?)emulsion could be produced in-situ. In addition, thestudy was to investigate the potential benefit of addingcarbon dioxide to hot water to improve bitumen recovery.The results prove that when the pH of producedfluids is between 10.5 and 11.5, the O/W emulsionpredominates. The emulsion is stable and has a viscositymuch lower than that of the oil itself, due to thecontinuous water phase, and should beneficial in therecovery of heavy oil and bitumen. When the producedfluids have a pH less than 10.5, the water-in-oil (W/O)emulsion predominates. The laboratory data indicate thateven this type of emulsion behaves as an O/W in the corebut it is unstable and when produced the droplets quicklycoalesce and immediately form the observed W/O emulsion.The addition of carbon dioxide to hot water at lowtemperatures proved to be effective in improving bitumenrecovery over that from hot water alone. This isbelieved to be due to the effect of carbon dioxideabsorption in reducing bitumen viscosity which resultedin improved bitumen mobilization. Another beneficialeffect is the increase in pressure gradient due to thepresence of free carbon dioxide, beyond the solubilitylimit, in the injected stream. The hot water-CO2 runsproduces mostly W/O emulsion. The best recovery wasachieved when the produced fluids temperature was around130°C.