| Popis: |
Canada has declining reserves of conventional oil, but vast reserves of heavy oil and bitumen. Over 90% of the world's heavy oil and bitumen trapped in sandstones and carbonates are deposited in Canada and Venezuela. Up to 80% of estimated reserves could be recovered by in-situ thermal operation. The current in-situ thermal technologies such as cyclic steam stimulation (CSS), steam flooding and steam-assisted gravity drainage (SAGD) are energy intensive and use large quantities of fresh water. Increasing pressure of environmental concerns and the threat of a carbon tax will make it imperative to find new oil extraction technologies that are less energy intensive and that use less water. Combining technologies in the form of hybrid steam-solvent processes offer the potential of higher oil rates and recoveries, but at less energy and water consumption than processes such as SAGD. At the Alberta Research Council, new hybrid steam-solvent processes have been undergoing development in recent years. The Expanding Solvent-SAGD (ES-SAGD)(1–2), is aimed at improving and extending SAGD performance by solvent addition to steam. The improvements include higher and faster drainage rates, lower energy and water requirements and reduced green house gas (GHG) emissions. The Thermal Solvent Hydrid process focuses on combining solvent with a small amount of steam in a VAPEX (vapour extraction) process(3–4). This process offers the potential of higher rates than cold solvent VAPEX at less energy consumption than SAGD. Hybrid steam-solvent processes, when fully developed, will extract oil at lower cost than SAGD and will also open currently marginal resources for exploitation, increasing oil reserves. This paper presents and discusses the principal concepts and key parameters for the new hybrid steam-solvent processes and compares expected performance to SAGD. |
