CO2-based heavy oil recovery processes for post-CHOPS reservoirs

Amin Sharifi Haddad, Ian Gates (Corresponding Author)

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33 Citations (Scopus)
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Cold Heavy Oil Production with Sand (CHOPS) is currently the process of choice for recovery from unconsolidated solution-gas rich heavy oil reservoirs. Compared to waterflood and thermal recovery processes, primary processes such as CHOPS have relatively low energy and emission intensities; in other words, they can be considered as relatively ‘clean’ fossil fuel energy recovery processes. However, with recovery factors between 5 and 15% at the end of its economic life, there is a search for follow-up processes that yield additional oil from these reservoirs with continued low energy and emission intensities. One option is CO2-based enhanced oil recovery (EOR) processes – CO2 can lower oil viscosity and if some fraction of the injected CO2 is sequestered in the reservoir, then the process can be considered a CO2 storage process in addition to an oil follow-up recovery process. Here, we evaluate the energy return and CO2 sequestered in cyclic CO2 and cyclic CO2-hot water injection processes in a post-CHOPS heavy oil field. The results reveal that overall recovery factors can be raised through appropriate design of the CO2 follow-up process. Cyclic CO2 injection achieves an incremental 2.4% recovery factor (over 4 years of operation) with high energy return ratio whereas CO2-hot water processes achieve higher recovery factors with lower energy return ratios. In these processes, the amount of CO2 that remains sequestered in the reservoir is small, typically less than 5%. Thus, these EOR processes are not strong candidates for CO2 sequestration.
Original languageEnglish
Pages (from-to)238-246
Number of pages9
JournalJournal of CO2 Utilization
Early online date15 Apr 2017
Publication statusPublished - May 2017

Bibliographical note

Authors would like to thank the financial support of the Petroleum Technology Research Centre Saskatchewan (PTRC) for this project, and Computer Modeling Group Ltd. for the use of their thermal reservoir simulation software CMG STARSTM. We would also like to thank Jacky Wang for his help and comments on the modeling part of this study.


  • heavy oil
  • cold production of heavy oil with sand
  • post-CHOPS
  • CO2 injection
  • follow-up recovery processes


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