HOTS (heavy oil and tar sands) oils and bitumens are becoming significant in world and Canadian production, yet current employed recovery technologies (CSS, SAGD, mining) are inefficient in terms of recovery, energy and water intensity, and cost to the environment. Reservoir and reservoir fluid heterogeneities are ubiquitous in HOTS reservoirs and impactreservoir processes that depend on uniform oil mobility to work effectively e.g. SAGD or that are limited to reservoirs that can withstand high pressure processes e.g. CSS. Concerns about greenhouse gas emissions and water usage, combined with societal pressure to implement more sustainable energy recovery procedures require the development of much more effective recovery processes. An understanding of the geological and fluid heterogeneity typically found across heavy oil and bitumen provinces will assist in the transition from current processes (SAGD, CSS) to Reduced Emission to Atmosphere Recovery (REAR) processes, to Zero Emission To Atmosphere Recovery (ZETAR) processes. We discuss REAR processes initially based on optimizing current recovery processes to complex oil mobility distributions (geotailoring) by improving reservoir and fluid description processes and linking this to improved engineering solutions by refining well placement and operating conditions. The next step in recovery process evolution involves processes designed upfront to be geotolerant of complex and discontinuous geological facies but not requiring high pressure steam and reservoir fracturing strategies. Finally we review progress towards achieving efficient energy recovery from HOTS and possible routes ZETAR processes. These include the acceleration of microbial processes in reservoir to recover energy as methane, or ashydrogen as an intermediate product of biodegradation, which may be feasible under special conditions, and the capture or recycling of carbon using biological processes.
Heavy oil and tar sand (HOTS) oils and bitumens are becoming larger portions of world and Canadian production, yet technologies employed are, despite great advances, inefficient in recovery terms (e.g. CHOPS or waterfloods), expensive in energy, water and environmental costs (SAGD, CSS, mining), ineffective in the bulk of reservoirs that have restricted vertical permeability (VAPEX, SAGD), or are limited to reservoirs that can withstand high pressures (CSS). Hydrogen requirements for upgrading impose additional environmental and economic premiums. Concerns related to greenhouse gas emission and water usage, combined with societal pressure to implement more sustainable energy recovery procedures all require the quick development of much more effective recovery processes. However, sustained high oil prices and profitable existing technologies plus restricted R&D capacity in the energy sector may encourage the business status quo. There is thus a need for quickly deployable, more sustainable transition recovery methods that can quickly effect large reductions in the environmental footprint while maintaining perceived short term economic needs. The transition from current processes e.g. SAGD and CSS via Reduced Emission to Atmosphere Recovery (REAR) processes, to Zero Emission To Atmosphere Recovery (ZETAR) processes will combine advances in fuelingystems, carbon capture, in-situ heat and gas generation, in-situ and surface upgrading and the business/regulatory environment, as well as recovery process design itself.
