Performance Evaluation of an Enhanced Cyclic Solvent Process (ECSP) for Thin Heavy Oil Reservoirs

Canada’s energy future depends on heavy oil resources, which are mainly located in Western Canada, i.e., Saskatchewan and Alberta, and account for almost half of the total world heavy oil reserves. At present, only 8-9% of the original oil in place (OOIP) can be recovered in such heavy oil reservoirs with the current available technology because the oil is very viscous and contained in thin formations. It has been found that cyclic steam stimulation and steam-assisted gravity drainage (SAGD) and vapour extraction (VAPEX) often do not work for recovering heavy oil in such thin reservoirs. The enhanced cyclic solvent process (ECSP) experimentally shows its potential to increase heavy oil recovery in such thin formations by using methane (CH4) and propane (C3H8) as two separate slugs in a cyclic manner. So far, no comprehensive numerical simulation has been conducted to evaluate the performance of the ECSP in the laboratory- and field-scale. Pressure-volume-temperature (PVT) tests have been performed for the solvent(s)-heavy oil systems. Then, the PVT properties are simulated by using the CMG WinProp module. For the CH4-C3H8-heavy oil mixture, the swelling factor of heavy oil maintains at a relatively high value for each test temperature, while the measured saturation pressures are also found to have high values. The tuned Peng-Robinson equation of state (PR EOS) (1978) model can be used to reproduce the saturation pressures and swelling factors with an average relative error of 3.68% and 3.76%, respectively, while the modified viscosity model is able to predict the viscosity of solvent(s)-heavy oil systems with an average relative error of 10.74%. Numerical techniques are developed to history match the ECSP profile in the laboratory scale, while efforts have been made to examine the effects of molecular diffusion, dispersion, and foamy oil behaviour on the ultimate oil recovery. Finally, the operational parameters are optimized by using the orthogonal design method. There exists a good agreement between the experimental and numerical results for each individual ECSP test. As for the diffusion coefficient, a minor impact on the oil recovery is observed while the dispersion coefficient imposes a strong impact. The reaction frequency factor (RFF) for gas exsolution from bubble to gas phase almost shows no influence on the simulated oil recovery. In comparison, the RFFs for gas dissolution and exsolution from oil phase to bubble affect the oil recovery to a larger extent. The injection pressure of CH4 and minimum production pressure are found to be the most sensitive parameters. The field-scale simulation is conducted to evaluate the ECSP performance in the Pelican oilfield. Subsequently, the orthogonal design method is applied to optimize the operational parameters. Finally, these optimized operational parameters are selected to predict the production performance. There exists a good agreement between the simulated production profiles and the observed field data. The minimum well bottomhole pressure is found to be the most sensitive parameter while the injection time of CH4 and C3H8 as well as soaking time are also subject to relatively large sensitivities. As for the ECSP performance, the cumulative oil production increases quickly with time once the ECSP is initiated, and then its increasing rate slows down slightly after two years of production. After ECSP treatment, the oil saturation decreases due to good oil production near the wellbore and the exsolution of solution gas from heavy oil.

Name thesis:degree_name

Master of Applied Science (MASc)

Level thesis:degree_level

Master's

Discipline thesis:degree_discipline

Engineering - Petroleum Systems

Grantor dc:publisher

Faculty of Graduate Studies and Research, University of Regina

Year dc:date.issued

2013

Author dc:creator

• Yang, Ping

Advisor dc:contributor.advisor

• Yang, Daoyong (Tony)

Committee members dc:contributor.committeemember

• Torabi, Farshid
• Luo, Peng

Language dc:language.iso

en

DOI

https://doi.org/10.82465/4296

OAI identifier oai:identifier

oai:uregina.scholaris.ca:10294/5401