Advancing Thermal and Carbon Dioxide Recovery Methods beyond their Conventional Limits: Downhole Innovation

Abstract

Steam or CO 2 injection methods account for most of the oil recovered worldwide with Enhanced Oil Recovery (EOR) methods. Currently heavy oil production is less than 7% of the world's oil production; this percentage is not expected to increase dramatically without significant changes in reservoir management. Steam and CO 2 have been used successfully since early 1960s --steam in viscous heavy oils and CO 2 mostly in pressurized light oil fields but also in some heavy oil fields. What limits a wider application is depth and high pressure for steam and CO 2 availability for the relatively large inventory of light oil fields that exist worldwide. Although there is some overlap in fields that could benefit from either application, there are not many recorded attempts to implement both methods simultaneously. Air injection, although it was tried first as an EOR method, has not been widely implemented as in-situ combustion is difficult to control in shallow reservoirs and especially without water coinjection.The paper describes the benefits that result from operation of a downhole steam generation (DHSG) which combines thermal and nitrogen or CO 2 EOR. In addition, by controlling the ratios of steam, excess CO 2 and excess O 2 (where applicable) it is possible to use in-situ oxidation in a controlled manner and accelerate production of oil. Moreover, the CO 2 that is generated by in situ can be used elsewhere. The paper includes discussion of conceptual reservoir simulation and economic studies that demonstrate the applicability of DHSG in deeper warm-climate conventional heavy oil fields, as well as challenging arctic environments.Advances from the aerospace industry that enabled this DHSG system, the surface processing design, and well placement strategies are also discussed in this article. They provide an overview of the entire recovery system and present an opportunity to develop both virgin resources and oil fields that were prolific in primary and secondary operations and are rightfully candidates for EOR.

Advancements, Challenges, and Perspectives of Flue Gas Injection in Subsurface Formations: A Comprehensive Review

“…20 Furthermore, produced flue gas can move faster than steam as it does not need to preheat the reservoir to provide the circumstances for gas dissolution in heavy oil. 20 So, flue gas can deliver a massive amount of energy during the injection process at lower temperatures, which was comprehensively discussed by Capper et al 21 Monte-Mor et al 22 developed a set of experiments to evaluate the effectiveness of produced flue gas by down hole steam generators coupled with the dynamic steam injection to recover heavy oil (16.14°API) from sand pack, representing the sandstone reservoirs. They observed that flue gas and steam coinjection can reduce the steam volume (10% less steam) more than steam-only injection to produce the same amount of crude oil.…”

Evaluación de la influencia de los gases de combustión en procesos de inyección continua de vapor utilizando generadores de vapor en fondo

“…La combinación de vapor y gases de combustión modifica el perfil de inyección, ya que a medida que se disuelve y difunde el CO 2 en el crudo, el vapor tendrá un mayor radio de calentamiento. [3,11,12] Si el CO 2 no alcanza la PMM se comportará de forma inmiscible, al igual que el N 2 , que tiene presiones mínimas de miscibilidad elevadas (superiores a los 5.000psi [13]), En condiciones inmiscibles existe recuperación de aceite por hinchazón y vaporización limitada del gas; no obstante, el mecanismo predominante es de desplazamiento por empuje.…”

Enhanced Oil Recovery Techniques for Indian Reservoirs

“…Four common recovery methods involving thermal injection are: in situ combustion (ISC); cyclic steam stimulation (huff and puff/ CSS); steam-assisted gravity drainage (SAGD) and high pressure air injection (HPAI). Figure 11 shows schematically the ISC, which employs the injection of air to ignite the small fraction of oil, generates heat internally, and produces the combustion gases to enhance the oil recovery especially for heavy oil sandstone reservoirs (Yazdani and Maini 2005;Alvarado and Manrique 2010;Capper et al 2011;Knorr and Imran, 2011). Figure 12 shows schematically the CSS.…”