Heavy Oil Recovery via Combination of Radio-Frequency Heating With Solvent Injection

Abstract

Being the most popular technological framework for the heavy oil and bitumen production, the reservoir heating is mainly performed via steam injection. Progressively it becomes evident, however, that there exist other methods offering an efficient production for various initial reservoir conditions and oil properties. The electromagnetic (EM) heating assisted oil recovery is one of them capable to be an alternative to conventional approaches where they become inacceptable.Physically speaking the radio-frequency (RF) heat generation results from so-called microwave effect i.e. rotation with friction of polar molecules in the EM field. The intrinsic advantages of the RF-heating (RFH) based technology, which in particular avoids the problems associated to water supply and water treatment, can be strengthened by solvent injection. After certain period of preheating this may lead directly to improved oil recovery due to additional oil viscosity drop as a result of oil-solvent mixture process. Along with this the solvent injection may reduce the operational in-situ temperature and thus, to increase the energy efficiency (i.e. the amount of energy required per unit of oil production). This will open a way to the successful technology application in shallow and/or thin reservoir. Mention also that the combination of heat and solvent supply has recently been field-tested.Recently the large-scale EM heating models have been developed for numerical simulation of realistic RFH applications, which provided the technical basis for critical analysis of the oil recovery processes. The numerical methodology based on loose coupling between dedicated reservoir and electromagnetic simulators, has been applied to study the combination (and competition) of two principal physical mechanisms of oil viscosity reduction associated with heat and solvent mass transfer. Taking advantage of the field-scale modelling the evaluation of operational conditions providing the oil production efficiency has been done. It was shown that RFH and its modification can be efficient for the various reservoir conditions. Noticeably different solutions for well configurations can be envisaged in the technology under consideration.The simulations have included the pure RFH cases at variable total EM power and the RFH combination with solvent injection at different operational and well. The initial reservoir conditions and properties corresponded to typical Athabasca reservoir. Main results comprising the methodological aspects of the recent 3D code development, the conclusions on pure RFH advantages and drawbacks and the demonstration of enhanced oil recovery efficiency at solvent injection within the RFH framework, are presented in detail. The role of particular mass transfer mechanisms and their contribution to improved process efficiency in heterogeneous matrix are quantified and discussed.The solvent injection combination with electromagnetic (radio-freqency) heating may become a promising issue in many practical applications.