Investigation of Electromagnetic Heating Methods for Heavy Oil Reservoirs

SAHNI, AKSHAY, Consultant

Much of the remaining hydrocarbon resources are in the form for very heavy oil or tar. The low mobility of the oil makes it production difficult, unless some external source of heat is applied to it. 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. Field performance and simulation studies have shown that for very deep reservoirs, small thickness of the oil-bearing zone, higher reservoir pressures and reservoir heterogeneity significantly impact the performance of steam injection.This paper addresses some of the fundamental heat transfer issues, which limit the applicability of steam in these situations and discusses alternative methods of transferring heat to oil reservoirs, based on electromagnetic energy. Some examples discussed and modeled are high frequency microwave heating and low frequency resistive heating. We start by looking at simple analytical radial flow models of electromagnetic heating for homogeneous reservoirs. Then we model more complex cases using finite difference simulations of multi-phase fluid flow, heat transfer and phase behavior. Results show that in some cases, electromagnetic heating is a favorable alternative to steam injection, in terms of both oil recovery performance and economics.

Much of the remaining hydrocarbon resources are in the form for very heavy oil or tar. The low mobility of the oil makes it production difficult, unless some external source of heat is applied to it. 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. Field performance and simulation studies have shown that for very deep reservoirs, small thickness of the oil-bearing zone, higher reservoir pressures and reservoir heterogeneity significantly impact the performance of steam injection.This paper addresses some of the fundamental heat transfer issues, which limit the applicability of steam in these situations and discusses alternative methods of transferring heat to oil reservoirs, based on electromagnetic energy. Some examples discussed and modeled are high frequency microwave heating and low frequency resistive heating. We start by looking at simple analytical radial flow models of electromagnetic heating for homogeneous reservoirs. Then we model more complex cases using finite difference simulations of multi-phase fluid flow, heat transfer and phase behavior. Results show that in some cases, electromagnetic heating is a favorable alternative to steam injection, in terms of both oil recovery performance and economics.

AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California