Sign Up for FREE Daily Energy News
Hazloc Heaters
Copper Tip Energy Services
WEC - Western Engineered Containment
WEC - Western Engineered Containment
Copper Tip Energy
Hazloc Heaters

Technical Product Report: Comprehensive Assessment of Toe-To-Heel Air Injection (THAI) Process

Guidelines for Development of Future Generations of In-Situ Combustion Processes




THAI is a novel in-situ combustion (ISC) process in which the horizontal section of the horizontal producer is located close to the bottom of pay section and it has its toe close to a vertical air injection well.  Once initiated, the ISC front is propagated from toe-to-heel of the horizontal section of the production well.

USA patent: 5,626, 191/May 6, 1997; expired in 2015
Canadian patent 2,176, 639/August 2, 2000; expired in 2016

As seen in the bird’s-eye view (Picture 1 and picture 2), the process can be applied in two geometrical configurations: direct line drive and staggered line drive.  As seen in the cross-section view (Picture 3), the ISC front is leaning forward and propagates from the toe to the heel of horizontal producer. Upgrading of the oil is preserved because the oil displaced by ISC front travels only a short-distance through a relatively high temperature region called Mobile Oil Zone (MOZ).  Hydrogen is produced possibly due to coke gasification and water-gas shift reactions.

Technical Product Report - Comprehensive Assessment of Toe-To-Heel Air Injection (THAI) Process

THAI is the first Enhanced Oil Recovery (EOR) process, which produces oil that is upgraded underground, i.e. within the reservoir, whilst simultaneously the upgraded oil is displaced by the ISC front towards the production well.  Moreover, THAI is the first EOR process that produces hydrogen in the effluent gas.  In reality, THAI constitutes a small field, partial upgrader – in practice, the only one existent in situ upgrader in the Upstream Industry.  By using a suitable catalyst-containing-gravel pack, wrapped around the horizontal section of the producer, a second upgrading occurs when oil enters the borehole; in this way, a second novel process, called catalytic THAI or CAPRI (CAtalytic Upgrading RRocess In-situ), is created as an ‘add-on’ process to THAI (Picture 4).

Technical Product Report - Comprehensive Assessment of Toe-To-Heel Air Injection (THAI) Process 2

Note: In the CAPRI process, horizontal producer constitutes a “sui generis” radial flow catalytic reactor

An important feature of the THAI process is its self-healing feature as far as the complete oxygen consumption is concerned. This is related to the existence of a local blockage (coke-plug) at the intersection of the ISC front with the horizontal section of the horizontal producer and to the controlled gas-liquid gravity segregation (gravity over-ridding of the ISC front).

STATUS OF FIELD TESTING OF THE THAI PROCESS: In the last 14 years, seven THAI field tests have been carried out in China, India and Canada. The earliest two pilots were conducted in Canada: Whitesands pilot in Athabasca started in 2006 and Kerrobert pilot in Saskatchewan started in 2009.  The potential of THAI process for underground upgrading and hydrogen production was fully demonstrated by the field pilots. For more details see the website:


The main lessons from these field tests, as well as the status of advancement in the laboratory testing and the simulation – conducted within the last 25 years – are presented and discussed in this comprehensive report; further improvements to the process are proposed. Also, guidelines for development of future generations of in-situ combustion processes are analyzed.

ASSISTANCE FOR THAI APPLICATION: The consideration is made to provide the THAI Report as an in-kind donation to the companies interested in further development of the THAI process or of the CAPRI process.

Technical assistance can be provided in the following areas:

  • Semi-commercial field THAI application
  • Field testing of CAPRI process
  • Underground oil upgrading using in-situ combustion, especially via THAI/CAPRI processes
  • Hydrogen production during THAI process within the frame of hydrogen-clean energy policy.

Share This:

More News Articles

New SHOWCASE Directory Companies


Challenger Geomatics
Caliper Inspection
CDN Controls
Gemini Fabrication
DyCat Solutions
Environmental Mats
Canline Pipeline Solutions