The Mechanisms of Electrical Heating for the Recovery of Bitumen From Oil Sands

摘要

Electrical heating of the Alberta oil sands for the recovery of bitumen has been studied since the early 1970''s. The technology has evolved as an additional technology to SAGD and surface mining. This paper describes the heat and mass transfer mechanisms associated with a specific application of electrical heating, the Electro-Thermal Dynamic Stripping Process (ET-DSP™), for the production of bitumen from the oil sands. Given that heat is created in the oil sand as a current flows through the connate water and that initially all the fluids are immobile, the end result is a pressure and temperature distribution that is characteristic of an electrical heating process. To effectively recover the heated bitumen from the oil sand requires an understanding of the heat and mass transfer mechanisms associated with the pressure and temperature distribution, as well as gravity forces. The electrical heating process changes as the oil sand increases in temperature and the bitumen is produced. This results in a dynamic process whereby the heat, mass and electromagnetic fields are strongly coupled and in a transient state throughout the entire recovery process. The dominant mechanisms of the electrical heating recovery process are presented in terms of fundamental equations and solved numerically. A 3D quasi-harmonic finite element electromagnetic model is coupled to the mass and energy equations and solved in time. A recovery strategy based on an understanding of the recovery mechanisms is presented in terms of electrode spacing, duration of heating, energy supply and favourable operating requirements.