Formation resistive heating, commonly known as EM (Electro-Magnetic) heating, has been considered as a potential thermal recovery method in the viscous oil reservoirs for almost three decades. In situ viscosity reduction by the heat generated in the formation helps in the recovery process. The formation acts as a resistor in the current flow path. Numerous patents and reports have been published on this. Application in deep reservoir and negligible heat loss in the overburden, are the two most important features of this thermal recovery process. There are examples of few pilots in Canada, Brazil and elsewhere. This also has been proposed as an option to accelerate SAGD start up.

This paper presents the limitation of EM heating in the formation and its applicability in few viscous oil reservoirs. It appears that in the EM heating process, heat penetration is significantly lower than that of a steam based process. Simulation of electrical heating in the simulator is tricky. The amount of estimated heat input is very sensitive to grid refinement. In reality, there is a potential for generating hot spots at the electrodes which was reported to be one of the reasons for failures in the field applications.

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