Thermal Assisted Gravity Drainage
Athabasca is pioneering the application of Thermal Assisted Gravity Drainage Technology (“TAGD”), an innovative process for the in situ recovery of Alberta’s subsurface bitumen deposits. The Company views TAGD as a potential production technology to tap the Company’s extensive bitumen resources contained in the porous carbonate reservoirs of the Leduc and Grosmont formations. Athabasca anticipates receiving regulatory approvals, in 2013, for the TAGD Pilot/Demonstration Project at Dover West.
TAGD uses an array of downhole electrical resistance heaters contained in coiled tubing which is installed in horizontal wells, heating the reservoir via thermal conduction. TAGD operates at lower temperatures than SAGD, leading to increased energy efficiencies and lower operational costs.
Because TAGD doesn’t require the use of water during the bitumen recovery process – there’s no need for costly steam generation and water treatment facilities – initial capital expenditures are significantly lower than those of comparably sized SAGD projects.
Data obtained during Athabasca’s 2012 and 2013 production tests at Dover West have enabled Athabasca to model the carbonate reservoir, simulating the performance of a TAGD commercial project in the Leduc carbonates. During Q1 2013, Athabasca conducted a third production phase of the TAGD technology at Dover West.
TAGD field tests in the Leduc carbonates – ancient coral reefs which are characterized today by excellent reservoir quality – indicate that effective reservoir permeability is considerably higher than previously anticipated. Data gathered during the three TAGD field production phases suggests that commercial-scale development requires heating of the horizontal wells to approximately 300 °C which, in turn, warms the surrounding carbonate reservoir to approximately 150 °C. Reservoir modeling simulations suggest single well production rates on the order of 1,000 to 2,000 bbl/d, depending upon reservoir thickness.