Unlocking Sustainable Solutions: Exploring Terpene-Based Green Solvents for Enhanced Heavy Oil Recovery

Abstract

The increasing global demand for heavy oil and bitumen underscores the need for innovative extraction techniques that address the challenges of high viscosity and low mobility. Traditional steam injection methods have been effective, but they are criticized for excessive water usage and significant carbon dioxide emissions. In response, this study investigates the use of terpenes�specifically limonene, citronella, turpentine, and beta-pinene�as sustainable and environmentally friendly solvents, comparing their performance with that of toluene, a commonly used but toxic solvent. This research involved 11 core flooding experiments using three different heavy oil samples (O1, O2, and O3) to assess the solvency and recovery efficiency of terpenes. Each experiment aimed to evaluate how terpenes influence oil recovery under varying conditions of steam and carbon dioxide injection and varying oil viscosities. Produced oil and water samples were collected at 20 min intervals and analyzed for emulsion stability and oil quality using TGA/DSC, while displacement efficiency was assessed through spent rock analysis. Results demonstrated that limonene, beta-pinene, and turpentine achieved oil recovery efficiencies comparable to toluene, approximately 75%, confirming their effectiveness as organic solvents. All terpenes acted as demulsifiers, enhancing the quality of the oil during production. Additionally, the study found that while steam-solvent injection negatively impacted oil recovery, carbon dioxide proved to be an effective secondary agent for enhancing oil production in lowerviscosity oils without compromising oil quality. The study concludes that terpenes hold promise as safe, effective, and sustainable solvents for heavy oil recovery. Their nontoxic nature, ease of handling, and effective performance position them as viable alternatives to conventional, harmful solvents like toluene. Furthermore, the use of carbon dioxide as a secondary injection medium offers a method to improve efficiency and reduce environmental impact, reinforcing the potential of terpene-based solvents in environmentally conscious heavy oil recovery practices. This research contributes valuable insights into the adoption of green solvents for advancing sustainable extraction methods.