The development of techno-economic and life cycle greenhouse gas models for the assessment of toe-to-heel air injection oil sands extraction technology

Abstract

• Toe-to-Heel Air Injection (THAI) is an emerging technology for oil sands extraction. • We developed techno-economic and greenhouse gas emission models for a THAI process . • Energy consumed for producing power ranges from 76.5 to 143.7 MJ/b. • GHG emission ranges from 64.3 to 174.3 kgCO 2 e/b. • Depending on regulations, the supply cost of dilbit ranges from C$35.2/b to C$54.7/b. Toe-to-Heel Air Injection (THAI) is a novel technology that uses in situ combustion concepts to mobilize oil sands from the reservoir to the processing facility. It eliminates the use of steam, a highly energy-intensive process, but produces gases that contain hydrocarbons, carbon dioxide, etc., which may affect its sustainability. While the THAI developer anticipated higher economic returns than the steam-based techniques, no study has been conducted to confirm the economic viability of THAI technology, particularly with the inclusion of carbon capture (CC) or carbon taxes. In this study, we developed detailed process models of the THAI technology to evaluate its energy, greenhouse gas (GHG) emissions, and economic performances. The effects of carbon tax policy and incorporating a CC were investigated. The results show that energy consumed for producing electrical power ranges from 76.5 to 143.7 MJ/b, and it is mostly driven by the injected air flow rate and discharged pressure. Aside from oil sands combustion in the reservoir, electricity is the main energy source. GHG emission ranges from 64.3 to 174.3 kgCO 2 e/b. The emission is mostly driven by air injection and produced gas flow rate. The supply cost of THAI’s dilbit (a blend of diluent with bitumen emulsion) ranges from C$35.2/b to C$45.1/b, but when taking into account carbon tax and CC, it ranges from C$38.2/b–C$48.9/b to C$42.2/b−C$54.7/b, respectively. Capital cost and carbon tax strongly influence the uncertainty in supply cost. The results also show that the THAI-based dilbit supply costs are economically viable when compared to current and short-term projected crude oil prices. The results of this study hold value for decision-making on policies and investments regarding THAI-based bitumen extraction technology.