Abstract
In-situ combustion is the most energy efficient of the thermal recovery methods. In light oil reservoirs, too little fuel may be deposited thus making combustion impossible while in heavy oil reservoirs too much fuel may be deposited thus ruining the economics of the process. A research program has been initiated to try to solve these problems. Water soluble metallic additives were tested to attempt to modify the fuel deposition reactions.
In a previous paper1, results were reported from kinetics experiments run on Huntington Beach, California and Hamaca, Venezuela crude oils in the presence of aqueous solutions of metallic salts. While the presence of copper, nickel and cadmium had little or no effect; iron, tin, zinc and aluminium increased fuel laydown for Huntington Beach oil. The results were similar for the heavier Hamaca oil.
This paper describes thirteen combustion tube runs using four different crudes. In addition to the above two crude oils, a 12° API and a 34° API Californian oil were tested. The metallic additives iron, tin and zinc improved the combustion efficiency in all cases. Fluctuations in the produced gases were observed in all control runs but disappeared with the iron and tin additives. The front velocities were increased by the metallic additives. Changes were also observed in H/C ratio of the fuel, heat of combustion, air requirements and density of the crude produced. The amount of fuel deposited varied between the oils. For Huntington Beach oil, the amount of fuel increased in the order: zinc, control, tin and iron while for the Hamaca crude the order was: control, iron and tin. The most interesting result occured with the light California oil. The control run showed that we were unable to propagate a combustion front while with iron additive a good combustion was achieved.
To date we have not been able to find a suitable additive to reduce fuel deposition. Iron and tin salts seem suitable agents to increase fuel when that is needed.
