Canada's oil sands deposits in northern Alberta contain more than 1.35 trillion barrels (~215 billion m3) of bitumen. Such a large resource base, even allowing for (relatively) low recovery factors, still constitutes the world's second largest oil reserves (behind only Saudi Arabia's). In-situ recovery technologies for these deposits, in view of the extremely viscous bitumen typically existing in them, commonly require thermal heating and/or solvent dilution to mobilize the bitumen and enable it to be produced. Steam-Assisted Gravity Drainage (SAGD) and Ccyclic-Steam Stimulation (CSS) are currently two technologies accounting for the bulk of in-situ bitumen production in Canada.
This paper briefly reviews key developments of the SAGD process. It next analyzes the production performance of a long-running Clearwater-FM SAGD well pair, followed by the presentation of history-match simulation results for this SAGD well pair. Discussion of the results is given from the viewpoint of Level-I (matching rates, volumes, fluid ratios) and Level-II (matching steam chamber behaviour) history match. These results demonstrate clearly the challenges of history-match simulation for the SAGD process, as well as the utility (or lack of) of Level-I and Level-II matches. Discussion and conclusions are also offered of the potential pitfalls associated with interpretation of history-match simulation results for the SAGD process, and subsequent implications for SAGD reservoir management.