Experimental studies on 'foamy oil' phenomena

This research was directed towards an experimental investigation of foamy oil phenomena, which holds considerable promise for the recovery of heavy oil from solution gas drive reservoirs exhibiting foamy oil characteristics. A recombined Lloydminster heavy oil and CO2 was used in all the experiments. The heavy oil viscosity at ambient conditions was 14000 mPa.s. The runs were carried out at room temperature of 22°C, +/- 0.5°C. A 0.5% (by volume) defoamer was added to several experiments to help liberate gas bubbles from the dispersed gas phase to free gas and to elucidate the effect of the pressure depletion rate on the anomalous production of foamy oil.;A series of constant composition expansion, CCE, experiments was conducted using a visual PVT cell. The CCE runs were performed with two different pressure depletion rates of 41 and 800 kPa/hr at room temperature. Furthermore, they were performed under different conditions of mixing/no mixing, with and without the addition of defoamer, and in present of glass beads.;The viscosity was measured at two pressure depletion rates of 41 and 800 kPa/hr at room temperature and with and without the addition of defoamer. Three viscometers were used to measure the viscosity of foamy oil. Cambridge viscometer results showed an increase in foamy oil apparent viscosity with the decrease in pressure depletion rate. For the same pressure depletion rate, the addition of defoamer increased the foamy oil apparent viscosity. Capillary viscometer results were all within 5% from each other. Haake viscometer data were not reliable due to the development of free gas phase within the chamber.;A series of depletion visualization experiments were carried out using a high-pressure (6895kPa, 1000 psi) micromodel. The micromodel runs were performed with and without the presence of porous media and the addition of defoamer. Ottawa sand and Cryolite were used to pack the micromodel.;Visualization of the foamy oil depletion process revealed that several nucleation stages exist in a depletion process at the pore scale level. In all the micromodel runs, nucleation started at the furthest point from the outlet. Sand pack experiments with and without the addition of defoamer were performed at slow pressure depletion rates using two different sand packs.