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Orion Schrader Bluff satellite at Prudhoe to be developed in three phases
Kristen Nelson Petroleum News editor-in-chief
The state of Alaska has approved formation of the Schrader Bluff formation Orion participating area in the northwest corner of the Prudhoe Bay unit and approved an initial plan of development through May 31, 2005. In a Feb. 2 decision, the Alaska Division of Oil and Gas approved inclusion of portions of 14 leases and approximately 18,842 acres of the viscous Schrader Bluff formation in the participating area.
The Schrader Bluff accumulation was discovered in the Orion area in 1968, and since then more than 90 wells have penetrated the formation; most were completed in deeper formations. In November two wells, V-201 and V-202, were producing at a combined rate of 2,500 barrels per day.
Prudhoe Bay field operator BP Exploration (Alaska), the Orion operator, used data from the two producing wells, as well as a 3-D seismic survey, to delineate the extent of the Schrader Bluff within the Orion area. BP applied to form the participating area in October on behalf of itself and Chevron USA, ConocoPhillips Alaska, ExxonMobil Alaska Production and Forest Oil.
The state said the Schrader Bluff hydrocarbon accumulation in the Orion participating area is believed to extend to the boundary of the Milne Point unit Schrader Bluff participating area.
The Orion accumulation includes Schrader Bluff N and O sands at depths of 4,000 to 5,000 feet, and will be developed from existing Prudhoe Bay drill sites L, V, Z and W, and a possible new pad, I.
BP told the Alaska Oil and Gas Conservation Commission in its pool rules application that it estimates 1.07 billion to 1.785 billion barrels of oil in place, with waterflood recovery expected to be 20-25 percent of the oil in place, and peak production 30,000-50,000 barrels per day. Development in three phases Development at Orion will begin near the crest of the structure and move toward the outer margins.
“Phase I development targets the areas with good seismic quality and well control,” the state said, with drilling a combination of development and appraisal wells, “designed to provide early production and injection well performance information, while evaluating the fluid and rock quality in previously untested areas of the reservoir.” At V Pad, the V-201 and V-202 wells are on production and V-105 is on water injection for pressure support.
Phase I will include more V Pad wells and at least one L Pad well, a tri-lateral producer. A well may also be drilled in the W-Pad area in 2004 to test the southern area of the field.
Phase II will include completion of drilling from existing gravel pads, with 10 to 20 producers and 20 to 40 injectors on L, V and Z pads. There may be two additional producers and four to eight injectors on W Pad.
Phase III development will target the northwest portion of the field, an area that cannot be reached from L Pad, and would require construction of I Pad, which would have 10-20 producers and 20-40 injectors in the most northerly area of the reservoir.
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