ABSTRACT

Oil production from the Manor pool in southeast Saskatchewan is strictly from horizontal wells which penetrate the basal sandstones (P2 sands) of the lower member of the Watrous Formation. Manor differs from most horizontally developed pools in that commercial production from vertical wells was never sustained.

The Lower Watrous at Manor correlates with the lower member of the Amaranth Formation of Manitoba and the Saude Member of the Upper Spearfish in North Dakota. At Manor, basal sandstone reservoir units composed of interbedded sandstone and muddy siltstone are interpreted to have been deposited during a pause in the Lower Watrous transgression as subtidal bars or shoals in a marginal marine environment. They accumulated within a broad depression on the eroded Mississippian surface.

Average net pay within the basal sandy zone (P2) at Manor is 15 ft (4.5 m) with porosity and permeability averaging 19% and 10 md respectively. The relative success of horizontal wells versus vertical wells reflects the greater ability of the horizontal well to exploit the heterogeneity of the interbedded sandstone/siItstone reservoir because intersection with reservoir quality sands is increased.

The first horizontal well at Manor was drilled in March, 1992, at 1-18-7-1 W2M. Within two years, pool production rose to a rate of 6250 barrels (994 m3) of oil per day form 38 horizontal wells. Cumulative pool production reached 3 million barrels of oil only 2.5 years after production began. Due to a scarcity of existing vertical well control at Manor, extensive use was made of seismic, vertical stratigraphic tests, horizontal well-logging and petrographic data in developing the pool.