Reducing heavy oil carbon footprint and enhancing production through CO2 injection

The world's dependence on heavy oil production is on the rise as the existing conventional oil reservoirs mature and their production decline. Compared to conventional oil, heavy oil is much more viscous and hence its production is much more difficult. Various thermal methods and particularly steam injection are applied in the field to heat up the oil and to help with its flow and production. However, the thermal recovery methods are very energy intensive with significant negative environmental impact including the production of large quantities of CO2. Alternative non-thermal recovery methods are therefore needed to allow heavy oil production by more environmentally acceptable methods. Injection of CO2 in heavy oil reservoirs increases oil recovery while eliminating negative impacts of thermal methods.In this paper we present the results of a series of micromodel and coreflood experiments carried out to investigate the performance of CO2 injection in an extra-heavy crude oil as a method for enhancing heavy oil recovery and at the same time storing CO2. We reveal the pore-scale interactions of CO2–heavy oil–water and quantify the volume of CO2 which can be stored in these reservoirs.The results demonstrate that CO2 injection can provide an effective and environmentally friendly alternative method for heavy oil recovery. CO2 injection can be used independently or in conjunction with thermal recovery methods to reduce their carbon footprint by injecting the CO2 generated during steam generation in the reservoirs rather than releasing it in the atmosphere.

Research highlights▶ The final heavy oil recovery by CO2/water injection was more than twice as much as plain waterflood. ▶ Secondary CO2 injection recovered more oil compared to tertiary CO2 injection. ▶ However, the same amount of CO2 storage was achieved in secondary and tertiary CO2 injection.