Senlac, the Forgotten SAGD Project

Abstract

Summary The Senlac steam-assisted-gravity-drainage (SAGD) project in Saskatchewan, Canada, does not have the same name recognition as its much bigger brothers in the Alberta Oil Sands, but it certainly deserves to be known better. Senlac was the first industrial SAGD project in Canada, back in 1997, and since then, it has been the site for other technological innovations such as the use of solvent in addition with steam to increase recovery and reduce the steam/oil ratio (SOR), as well as the testing of wedge wells—wells drilled between SAGD well pairs to benefit from the heat remaining in the reservoir. The reservoir in Senlac is the Dina-Cummings of the Lower Cretaceous, and is much smaller than the McMurray formation, the site of most large-scale oil-sands projects, but the oil is only 5,000 cp; thus, it is mobile at reservoir temperature. This is a significant difference that allows well pairs to achieve excellent production and recovery even though reservoir thickness is only 8 to 16 m, well below the standard cutoff for SAGD. The presence of bottomwater under parts of the field is an added challenge to the operations. The paper will present the field characteristics and production performances as well as the main technological developments such as the solvent-added process (SAP) and the use of wedge wells. The paper will present a complete case study of an SAGD project in a heavy-oil reservoir where oil is mobile. Most SAGD projects so far have been conducted in bitumen, but the paper will show the potential for this technology in thinner and smaller reservoirs.