An experiment involving a steam drive process with aqueous surfactant (foaming agent) solution and nitrogen gas has been performed in a large-scale 90 cm physical simulator (51.8 cm ID by 91.4 cm long) at reservoir conditions to test the effectiveness of foam on the recovery of bitumen from Athabasca oil sands in Alberta, Canada. This paper describes the numerical simulation of this experiment. The objective was to demonstrate the capability of the numerical model to capture the significant mechanisms of the steam-surfactant-nitrogen drive process conducted in the 90 cm physical simulator.
The numerical simulation was successful in history matching the experiment. The in situ formation of foam and the diversion of injected steam into the oil rich zones by foam were idenrified by the numerical simulation. After approximately 35 pore volumes of steam had been injected, oil recovery was 51% of the initial oil in place.
The effectiveness of foam was studied by means of sensitivity tests using the numerical model. The study showed that enhancement of oil recovery could be achieved by adding surfactants and non-condensible gas to the injected steam. An analysis based on the simulation results indicated that a larger surfactant slug than that actually used in the experiment, would provide better oil recovery.
The steam drive process is used worldwide in recovering heavy oil and bitumen from underground reservoirs. The problems most often encountered in this process are steam channelling and gravity override. The process of adding aqueous surfactant (foaming agent) solution to the injected steam with or without non-condensible gas to form foam in situ is a promising technique which can provide a solution to these problems. Since foam is used as a selective blocking agent, which can optimize reservoir conformance, enhancement in oil recovery due to diversion of injected steam from the steam swept (depleted) zone into the oil rich zone is anticipated.
An experiment involving a steam drive process with aqueous surfactant solution and nitrogen gas was performed in a large-scale 90 crn physical simulator ar reservoir conditions to test me effectiveness of foam on the recovery of bitumen from Athabasca oil sands in Alberta. Canada. This paper describes the numerical simulation of this experiment. The objective was to demonstrate the capability of me numerical model to capture the significant mechanisms of the steam-surfactant- nitrogen drive process conducted in the 90 cm physical simulator.
Detailed descriptions of the experiment have been given by Ridley et al. The experimenml apparatus consisted of three components:
injection facility;
physical simulator, and
production facility.
A schematic diagram of the 90cm physical simulator, which was a high pressure cylindrically shaped cell (5l.8 cm ID by 91.4 cm long), is shown in Figure 1.
In the preparation of the cell, the cell was first positioned vertically on a special platform. 5 kg of clay was packed into the cell to form a thin clay layer which separated the test bed from the base of the cell.
