Numerical History Match of the Burnt Lake SAGD Process

The Burnt Lake Oil Sand Lease is located approximately 300 km northeast of Edmonton. The lease is estimated to contain 330x10(6) m(3) of bitumen in place in the Clearwater oil sands formation. Cold production was tested in the lease to recover 11 degrees API-12 degrees API crude bitumen between 1990-1993. Three pairs of SAGD operations began in April 1997 after 3 months of circulation. Many interesting characteristics were identified in the injection and production history. During the first year of operation, pressure and oil production rates decreased when steam injection rates were reduced. After the second year of operation, oil production rates responded inversely to steam injection rates. Oil rates were reduced when steam rates were increased, and oil rates increased when steam rates were reduced. Declines in oil rates were relatively slow over the entire operation period. When the steam injection was stopped for approximately 5 months after 5 years of operation, the operation pressure and oil production rates were gradually reduced during this period. Many other unexpected trends were also observed. All these features were consistently seen in all three pairs. This paper presents these behaviours in detail. A simulation study of 9 years of performance of Pair I was conducted to understand these characteristics. The history match demonstrated that oil production was achieved by two different mechanisms: one was expansion of the steam chamber and the other was drainage of oil from the layer above the steam chamber. Many unexpected performances were the result of the combination of these two recovery mechanisms.