Abstract

SAGD is an energy-intensive process with large amount of greenhouse gas (GHG) emissions and required water treatment. One option to reduce emissions and water is to use electromagnetic (EM) heating in either the induction (medium frequency) or radio frequency (RF) ranges. Since the early 1970s, research into the use of RF energy to effectively heat heavy oil reservoirs has led to incremental technology advancements. Since 2009, the Effective Solvent Extraction Incorporating Electromagnetic Heating (ESEIEH™, pronounced "easy") consortium suggested a process named similarly that dielectric heating of oil sand is combined with the injection of a solvent such as propane or butane to reduce bitumen viscosity. In January 2012, the mine face test was declared a success and confirmed the ability to generate, propagate, and distribute electromagnetic heat in an oil sand formation. Phase II of ESEIEH™ exploring scaled pilot tests with horizontal antenna in Suncor’s Dover facility is under developing. To distribute electromagnetic heating into the reservoir creation of desiccated zone and its controlled growth is a key. Since the reservoir is an electrically lossy environment, the growth of desiccated zone as a lossless medium helps the electromagnetic fields to propagate deeper into the formation and associated heating is also further developed within the reservoir. The water will continue to vaporize and move away from the "flashed or desiccated zone" at a rate which diminishes with time. Eventually it reaches the equilibrium condition that it cannot grow with given delivered RF power from the radiating antenna. In this study, the desiccated zone extension at its equilibrium is calculated on the basis of this concept to prevent the zone from collapsing. In this process, water should vaporize and leaks into reservoir to create the flow rate normal to the desiccated zone surface that pushes the water back and grow the zone. Another highlight on this study is to provide the solution for RF-heating avoiding the Lambert’s law or plane-wave assumption. Lambert’s law is (only) accurate and valid in guided-microwave structures or when the EM radiating source is far from the receiving load (relative to the wavelength), such as in optical regime or in telecommunication applications. Although, for heating applications, the maximum energy dissipation of RF waves takes place in the near-field region and not in the far-field region, hence, Lambert’s law does not give a correct solution in these cases. As a result of this study minimum required power is a function of reservoir mobility or in-situ water relative permeability. If efficiency of antenna is not high enough and reservoir mobility is greater than 10-3 then the RF power transmission system could not deliver enough energy to grow the desiccated zone.

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