Use of vacuum-insulated tubing (VIT) in thermal (typically steam injection) wellbores dates back to at least the 1980s but, due to high cost and limited availability, its use until recently had been limited. While it has the potential to significantly reduce heat losses to overburden, thereby improving well operating economics, the correct application of VIT can be more of an art rather than science given the factors that impact its performance. These include understanding how VIT is manufactured and what design elements influence good long-term performance, what quality assurance is used during manufacture and on the finished product, how to confirm actual k-factor (insulation) values on delivered product in lieu of advertised values, and how to verify true performance once the VIT is installed in a well. Recent new global sources of VIT have provided additional product choices for operators, as well as more competitive pricing, allowing VIT to be more broadly considered in projects where downhole heat losses must be actively managed to achieve the recovery performance desired. Calculation of heat loss reduction can be done with several different programs, but careful attention must be paid to the way the computer model is built to ensure results reflect actual, expected, field conditions.

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.