Electromagnetic Heating Methods for Heavy Oil Reservoirs

Abstract The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that low injectivity reservoirs and small thickness of the oil-bearing zone limit the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. We present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (microwave frequency). We show the applicability of electromagnetic heating in two example reservoirs. The first reservoir has thin sand zones separated by impermeable shale layers and viscous oil (9541 cp at initial reservoir conditions). We model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir has low permeability and oil viscosity of 33 cp at initial reservoir conditions. In this case we use a high frequency microwave antenna located 30 ft from the producing well as the heat source. Simulation results presented in this paper suggest that electromagnetic heating may be a good stimulation technique for heavy oil reservoirs with low injectivity or with thin payzones. We identify the parameters which are critical for electromagnetic heating. We also discuss past field applications of electromagnetic heating as well as technical challenges and limitations.