The investigation into thermo recovery of heavy and extra-heavy oil through the use of different injection strategies and additives in order to improve the effectiveness of hot water or steam recovery processes has been of ongoing interest. This paper investigates correlations between the essential characteristics of a thermorecovery process and the quality of produced oil emulsions using analysis of produced oil emulsions collected from 1arge numbers of laboratory simulated steamdrive and hot water processes in addition to one field situation.
Variations in the relative amounts of oil present in both water and oil emulsions that were collected at different points in time during 60 different laboratory simulations, were systematically investigated and compared to similar field-produced samples.
This study indicates that the amounts of water-in-oil emulsions play a dominant role in determining the total amounts of oil produced. However, the water emulsion quantities observed in the collected and analyzed samples, can be significantly for hot water recovery processes taking place under low pressure drop, bypass dominated conditions. Novel laboratory methods were developed and tested so as to cover a large spectrum of emulsion qualities obtained from both field pilots and laboratory simulations.
Qualitative observations of the emulsions indicate that some essential modifications are suffered by the produced fluids during flow and cooling process, causing separation in surface and downhole equipment.
Production fluids from the in situ, thermal recovery of heavy oil from oil sand reservoirs present a unique problem in fluid handling for the operators of such projects. The ability to predict the nature of these fluids in terms of their oil content and the distribution of oil in the various phases is a prerequisite for a better design of the surface acilities.
The Athabasca deposit contains approximately 102 × 109 m3 of bitumen at an average depth at 400 m with average pay zones of 23 m. Because of its high viscosity (5 MPa.s at reservoir conditions) and low gas saturation, it cannot be produced using conventional means. The recovery methods currently being, investigated involve the injection of high pressure steam. At the Alberta Research Council, this process has been simulated by the use of physical models.
The primary objective of the majority of these experiments has been to gain an understanding of the processes involved in the recovery of heavy oil from unconsolidated oil sand reservoirs not amenable to surface mining techniques and find suitable methods for improving the economics of in situ recovery.
Observations made on produced fluids represent a valuable tool in the characterization of the recovery process. The existence and development of a hot fluid communication or bypass zone is characteristic in both single well steam stimulation (huff and puff) and steam or hot water continuous drive processes.One of the direct consequences of the gradual development of a flow, and recovery zone is, the formation of emulsions. The concentration of oil in produced fluids gradually increases until a maximum is reached (Figures la, 1b).