Among the most important features of the Clearwater Project is the low steam pressure at which both phases are designed to operate. The maximum operating pressure is expected to be approximately 1,000 kilopascals (kPa) or approximately 145 pounds per square inch (psi). This is approximately half the operating pressure used at other SAGD operations, which are typically 1,700-2,200 kPa.
Virtually all underground or in situ bitumen recovery projects require the addition of heat to enable the viscous bitumen to flow to the producing well. Steam is a proven and effective way to mobilize the bitumen. Higher steam pressure enables higher operating temperature, which is normally thought of as an advantage as it increases bitumen flow and therefore per-well productivity. Higher pressure, however, increases the risks of breaching the cap rock overlying the reservoir.
AOS has a strong commitment to safe operations. Bitumen drains effectively beginning at 140° C, and steam at 1,000 kPa has a temperature of approximately 180° C. Bitumen drainage at the Clearwater Project will be enhanced by co-injection of solvent, which will “thin” the bitumen and will complement the low-pressure production model.
AOS also sees technical advantages to low-pressure SAGD. Reduced pressure enables reducing the SOR, a major goal of nearly all SAGD projects. There is research suggesting that lower steam temperature with co-injection, while lengthening the recovery process due to lower per-well productivity, ultimately recovers a higher proportion of the reservoir’s original bitumen in place (OBIP).
The proposed maximum operating pressure at the Clearwater Project is being reviewed by the ERCB as part of AOS’s Clearwater Project application and, along with all of the other technical parameters, is subject to ERCB approval.