Achieving Sustainable, Optimal SAGD Operations

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Technology Update To meet the global demand for energy, the petroleum industry has been gradually increasing its development and exploitation of unconventional heavy-oil reserves. The production of heavy oil (broadly defined as having a gravity of less than 20°API) can be profitable, but operators usually generate lower profit margins than in light-oil production because of higher extraction cost, the need for diluents, upgrading cost, and the lower market price for heavier crude oils. Consequently, heavy-oil producers have to manage their assets in a sustainable manner by using the best technology available to minimize their total cost of operation and ensure a timely return on investment. The vast majority of the world’s heavy-oil reserves are found in Canada, Venezuela, and Russia. Canada has the largest heavy-oil reserves, approximately 175 billion recoverable bbl trapped in the form of oil sands. Extraction of heavy crude from the sands requires unconventional and unique methods (Farouq Ali 2003). The two preferred production methods are open-pit mining and in-situ processes, with steam-assisted gravity drainage (SAGD) being a commonly used in-situ method. Open-pit mining can be used to extract approximately 20% of the recoverable crude from oil sands, while in-situ methods such as SAGD can be used to produce the remaining 80%. In Canada, that would represent approximately 140 billion bbl. Open-pit mining is a mature technology with a large environmental footprint, and this method can only exploit resources near the surface. On the other hand, SAGD has a much smaller footprint, even as it unlocks reserves well beyond the reach of mining operations. Thus, in areas such as the Athabasca and Cold Lake regions of Alberta, SAGD operations have been emerging and rapidly expanding. Fig. 1 is an artistic representation of an SAGD facility, including some common injection points for oilfield chemicals. In SAGD, the two most common types of chemical treatments are related to emulsion separation and water clarification for reuse of water in steam generation.