Abstract
SAGD (Steam Assisted Gravity Drainage) thermal production of heavy oil in the area surrounding Lloydminster involves the injection of steam and subsequent pressurization of the reservoir. As fluid enters the horizontal producer, the pressure drop results in the deposition of calcium carbonate scale. Scale deposition eventually begins to have a detrimental effect on fluid inflow into the wellbore. In addition to the calcium carbonate scale, the high ashphaltene content of the oil results in a hydrocarbon coating being deposited on the scale. Many options exist to remove the scale/ashphaltene deposit and return the well to prior oil production rates. This paper will review the mechanism believed to cause scale deposition, available chemical and mechanical methods to remove the scale and Husky’s recent successes from treatment of SAGD wells in a sandstone reservoir in the Lloydminster heavy oil area.
