The newly discovered West Stoddart Field represents one of the largest Doig oil reservoirs in all of northeastern British Columbia, comprising at least four pools containing 50 million bbls of oil (7.95e6m3) and 8 Bd of gas (0.23e9m3). From the time that Remington Energy rig released the 16-32-87-21W6 discovery well on January 17, 1996 to October 1, 1997, Remington had drilled and completed 23 wells (6 vertical and 17 horizontal) into the Doig reservoir. The two dominant reservoir lithofacies encountered consist of: (1) moldic, vugular coquina and (2) very fine to medium grained, poorly consolidated, calcareous, massive to planar tabular bedded sandstone; representing a series of accreting shoal/bar complexes. The thickest net clean vertical sandicoquina sequence drilled vertically by Remington to date is 41 metres. Core analysis and petrophysical log evaluation support permeability and porosity maximums up to 3200 millidarcies and 17% respectively while calculated water saturations range between 6-7% and residual core oil saturations support an oil wet reservoir model.
Following the 16-32-87-21W6 discovery, 2D seismic was employed to follow up the initial discovery with the drilling of several additional wells which resulted in the 1-31-87-21W6 discovery and successful wells at 1-5-88-21W6 and 3-6-88-21W6. Upon the completion of the initial drilling program on the 2D seismic grid, the then understood geological model of the producing horizon suggested that the development drilling program would best be served with a 3D seismic survey. A 21 sq. mile 3D seismic survey was acquired in June of 1996 and employed to evaluate reservoir configuration and direct horizontal well trajectories. Calibration of seismic modeling and interpretation techniques to each new vertical well into the field permitted the development of a predictive model of gross sand thickness to be derived from the 3D seismic data. The result of this analysis is a development drilling success rate in excess of 80% as of October 1, 1997.
Oil and gas analysis from the West Stoddart Field indicate an oil API of 51 degrees and an H2S content of 6-11%. At a reservoir pressure of 18,000 kPa the Doig reservoir is at bubble point. Ga's cap expansion combined with gravity segregation provides the reservoir drive mechanism. Due to the absence of bottom water, horizontal wells positioned at or near the base of the reservoir minimize the drawdown while optimizing the reservoir energy from gas cap expansion and gravity drainage.
As of January 15, 1997 the West Stoddart facility was at full capacity, producing 2,700 bbls of oil and NGLs per day and 5mmd per day of gas from the first three horizontal and two vertical wells. As of October 1, 1997 the current facilities have been expanded to 10,000 bbls of oil and NGLs per day and 40 mmd per day of gas.
About the Author(s)
Doug Pruden is a University of Calgary graduate in geophysics (1980) with 17 years experience as a seismic interpreter and explorationist. He has worked for Chevron Canada, Canterra Energy, BowValley Energy and is currently chief geophysicist at Remington Energy. He has served as a 2nd vice president of the CSEG and been involved in several CSEG conventions as both a presenter and session moderator. He was co-author of the 1991 CSEG best paper award entitled "Structural Architecture and Evolution of the Dawson Creek Graben Complex; Alberta and British Columbia."
Peter Guyan is a University of British Columbia graduate in geology (1985) with 12 years industry experience. Peter has worked for Dome Petroleum/Amoco Canada, Petrorep Resources and is currently senior geologist at Remington Energy.