Other members of the consortium are oil sands producer Suncor Energy Inc. and Hatch Ltd.

In making the award, SDTC noted that Canada has some 170 billion barrels of recoverable crude oil stored in the oil sands. Of these remaining established reserves in Alberta, 80% are too deep to be mined and are currently recovered using in situ processes such as SAGD which is water- and energy- intensive.

N-Solv injects heated solvent (such as propane) vapor at moderate pressures into the gravity drainage chamber. The vapor flows from the injection well to the colder perimeter of the chamber where it condenses, delivering heat and fresh solvent directly to the bitumen extraction interface.

In solvent extraction, the production rate is limited by the rate that the solvent diffuses into the bitumen; the penetration rate of solvent into bitumen is determined by the bitumen viscosity. With Athabasca bitumen, a 25-30ºC temperature rise typically reduces the bitumen viscosity by a factor of 100. Thus, says N-Solv, a substantial acceleration in the bitumen extraction rate is achieved with a very modest increase in temperature. This is the key principle of N-Solv.

The use of solvent also preferentially extracts the valuable components in the bitumen while the problematic high molecular weight coke-forming species (asphaltenes) are left behind. The condensed solvent and oil then drain by gravity to the bottom of the chamber and are recovered via the production well.

Photomicrograph of an experimental sandpack. The fully extracted sand is upper, with residual asphaltenes dispersed throughout. Source: N-Solv. Click to enlarge.

The in situ solvent deasphalting is very selective and leaves the asphaltenes evenly dispersed throughout the extracted portion of the chamber. Post extraction core analyses show that the residue contains 60 to 70% asphaltenes. By leaving the majority of the asphaltenes behind the produced oil contains less sulphur, heavy metals (zinc, vanadium, iron) and carbon residue. This partially upgrades the oil to 13-16°API from a value of approximately 8°API for the raw bitumen. The produced oil is also less viscous, thus it requires less diluent for pipeline transportation to the refinery.

The (negative) impact of non-condensable gases on the extraction rates is critical, notes N-Solv. Non-condensable gases are released from the bitumen and accumulate in the reservoir if no special measures are taken. Increasing concentrations of non-condensable gases slow down the production rates. This effect can be severe and must be mitigated, the company says. The right circulation of solvent in the N-Solv process provides sufficient capacity to minimize and stabilize the concentration of non-condensables inside the reservoir. Through this built-in principle the process is able to sustain high production rates throughout, the company claims.

As the final step to prove the performance of the pure solvent under actual reservoir conditions, N-Solv will drill and complete a 300-meter producer and injector well pair and complete final engineering and construction of a supporting 500 barrel per day surface facility near Fort MacKay, Alberta.

Resources

• Developing an In-Situ Process for the Oil Sands

• N-Solv: The Profits of Energy Efficiency vs. the High Cost of Carbon Capture (2008)