Experimental Study on Oil Recovery from Oil Sands by dimethyl ether via the Displacement–Dissolution–Permeation Method

In response to high steam usage, significant greenhouse gas emissions, and secondary pollution risks associated with solvents in steam-assisted gravity drainage (SAGD) and solvent-assisted SAGD techniques for oil sands extraction, a new technology using liquid dimethyl ether (DME) for displacement–dissolution–permeation extraction (DME–DDP) has been proposed. Using a self-designed DME–DDP experimental apparatus, oil extraction experiments were conducted on consolidated oil sands samples to simulate the oil sand formations in the Athabasca region in Canada. The experimental results indicated that oil washing efficiency reached 84% under the optimal pressure gradient, with recoveries of >90% for saturates and aromatics, >60% for resins, and >50% for asphaltenes. The DME–DDP oil extraction process includes two stages, displacement and dissolution–permeation, each contributing to approximately 50% of the total oil recovery. The pressure gradient is the primary factor influencing oil washing efficiency, with higher recovery necessitating slower permeation or extended contact time between DME and crude oil in the formation. DME is a colorless, nontoxic, and nongreenhouse gas that can be recycled. These characteristics underscore the environmental sustainability and cost-effectiveness of the proposed method.