A New Technique for Heavy Oil Recovery Based on Electromagnetic Heating: Pilot Scale Experimental Validation

Abstract

Due to the depletion and the increasingly high cost of conventional light oil resources, in the future unconventional oils are due to become one of the major hydrocarbon source. In order to extract crude oil from these resources, a sufficiently low viscosity must be achieved, for instance through temperature increase. Electromagnetic irradiation can be a suitable method for in situ heating of reservoirs: major problems connected with this technique are the extremely high temperatures that can be reached at the well and the strong dependence on local variations of reservoir material properties. These problems can be solved to a large extent by inserting around the well, in proximity of the radiating element, a tight shell made of low-loss dielectric materials. The experimental work described in this paper aims to study the phenomena connected with the electromagnetic heating of an oil sand reservoir up to 150 °C, in order to assess the effectiveness of the novel tight shell conceptual design. Over 2000 kg of oil sand were inserted in a steel box and irradiated at 2.45 GHz frequency. The radiating element is a dipolar antenna inserted in the center of the oil sand volume. The temperature in the oil sand was recorded throughout the test in several points, in order to estimate temperature profiles along the distance from the antenna.
Results confirm that electromagnetic irradiation is capable of heating both wet and dry oil sands, since the temperature in the sample rises well above connate water boiling temperature. Water vaporization significantly impacts on temperature profiles and contributes to limit the temperature near the well. An even larger positive effect on energy distribution and heating homogeneity is assured by the low-loss shell realized around the antenna, that is extremely efficient in lowering the temperature in this critical zone.