Heavy Oil Late Life Energy Recovery—Maximizing the Value of Mature Thermal Assets

Abstract

The Heavy Oil Late Life Energy Recovery (HOLLER) project is the application of geothermal technology in steam assisted gravity drainage (SAGD) wells that are near end of life. While conventional geothermal technology is encumbered by the high cost of drilling deep wells to reach formations with the temperatures required for economic power generation, in situ bitumen producers have access to existing SAGD wells within mature reservoirs that are at shallow depths and high temperatures. The thermal energy from just one SAGD well can produce enough electricity to power thousands of homes for a year and major oilsands producers collectively have thousands of such wells. Our goal is to harness this thermal energy using the existing well inventory to create a closed geothermal system using process effluent water (PEW) such as boiler blowdown or tailings pond water as the heat recovery medium. This strategy has the potential to improve SAGD economics through incremental bitumen recovery, the generation of low-carbon base load electricity, and driving down SAGD greenhouse gas (GHG) emissions by recovering some of the spent energy. This strategy also provides an option to dispose process water and/or tailings water to accelerate the reclamation of tailings ponds. Suncor’s In Situ Technology team applied a stage-gated technology development process to progress HOLLER from Technology Readiness Level (TRL) 0—Idea to TRL 7—Field test. We applied the diverge-converge approach to 30 ideas that were distilled into four recommended commercial solutions. Our de-risking activities include numerical reservoir simulation, chemical process simulation, post-SAGD core and water analysis, laboratory studies for compatibility of various PEW sources with reservoir fluids and rock, core flooding, corrosion studies, facility design, economics, risk and uncertainty analysis, patenting, and testing in the field. As a result of the technology development work, we have developed a three-phase strategy to maximize the value of depleted in situ reservoirs: water disposal, energy recovery and permanent closure. This strategy offers synergies between mining and in situ operations, reduction in GHG emissions and environmental liabilities all while generating a net profit for the enterprise. If applied industry-wide, HOLLER technology has the potential of reducing not only the intensity, but also the absolute GHG emissions, while offering unique opportunities for collaboration between the in situ producers and mining operations. HOLLER is unique in its potential to retroactively reduce the GHG intensity of bitumen already recovered by thermal methods. It offers low emissions incremental bitumen production, nearly emissions-free power generation, increased efficiency of existing facilities through the direct use of recovered heat – while reducing mine tailings liabilities. HOLLER enhances the oilsands industry’s sustainability efforts.