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Pioneer requests Oooguruk changes Corps approved single trench to offshore drill site; company says three trenches allows for differences in pipe, utilities By Kristen Nelson Petroleum News
Pioneer Natural Resources Alaska has modified how it proposes to lay pipe and utility cables for its offshore North Slope Oooguruk discovery.
In a July application to the U.S. Army Corps of Engineers, Pioneer asked to modify the flow-line trench from the Oooguruk drill site, a man-made gravel island 5.7 miles offshore in East Harrison Bay. The Corps had approved a single trench in February. The current application is for three adjacent trenches: the primary trench would contain the flow-line bundle and a fiber-optic cable; the second trench would contain a power cable and a fiber-optic cable; and the third trench would carry two power cables.
Pioneer also proposes to modify the permitted flow-line route between the onshore flow-line transition at the coastline and the onshore tie-in pad, and install 32-40 thermo-siphons at the offshore to onshore flow-line transition.
The company said in a July 2006 project update prepared for regulators that gravel placement for the Oooguruk drill site island and the tie-in pad was completed in May. Planned summer activities include construction of the wharf/dock at the Oooguruk drill site, installation of well conductors at the offshore drilling island, installation of production modules and the camp, as well as gravel conditioning and installation of slope protection on the island.
Pioneer said in February that it had approved and was beginning development at Oooguruk. Pioneer is the operator and holds a 70 percent working interest; Eni Petroleum has a 30 percent working interest. The company said it expects to drill some 40 horizontal wells to develop 50 million to 90 million barrels of estimated gross oil resources. Pioneer: Oooguruk on schedule for first oil in 2008 The Department of Natural Resources said Aug. 3 that comments on the review for consistency with the Alaska Coastal Management Program are due Sept. 1; a final determination is expected to be issued by Sept. 21.
The department said pile driving for the pig launcher module is expected to take place in September and October, construction of a five-acre staging pad adjacent to the onshore production tie-in pad in September; installation of communications towers at the tie-in pad and the Oooguruk drill site in September and October; installation of the Oooguruk drill site camp in September; installation of the flow-line construction camp in November; installation of the eight-inch water injection flow-line tie-in to KRU DS-3A in January, construction of the pig launcher pad and road expansion in January; and installation of flowlines and cables in January.
In its second quarter results, issued Aug. 3, Pioneer said Oooguruk is on schedule for first oil production in 2008. Construction of the gravel drill site is complete, the company said, and 2006 work scheduled includes contouring and armoring the drill site, fabricating equipment and modifying the drilling rig for installation in 2007. Pioneer: five-acre staging pad needed The company said in a July 2006 project update prepared for regulators that gravel placement for the Oooguruk drill site and the tie-in pad was completed in May. Planned summer activities include construction of the wharf/dock at the Oooguruk drill site, installation of well conductors at the offshore drilling island, installation of production modules and the camp, as well as gravel conditioning and installation of slope protection on the island.
Pioneer said 2005-06 winter season construction activities “demonstrated a great need for storage and staging pads,” with the 2006-07 winter flow-line construction activities requiring “an intensive effort to install the modules, approximately 10 miles of flowlines and power and fiber-optic cables.”
A five-acre gravel staging pad is proposed adjacent to the west side of the on-shore tie-in pad to serve as a storage/staging area and an area for the temporary camp during Oooguruk construction. The pad would have approximately 250,000 square feet of usable space and would be used to mobilize a temporary 400-person camp to be used for housing construction personnel. The pad would house utilities, including propane tanks, power generation, fire water protection skids, a potable water system and blackwater storage tanks. The pad would also be used to store drilling support equipment, pipeline tubulars and vertical support members. Equipment would be stored at the pad in summer in preparation for winter activities.
Pioneer said keeping its facilities consolidated would minimize interference with existing Kuparuk River unit operations.
The staging pad would be used for the life of the project, an estimated 25 years, to consolidate equipment and materials storage.
Pioneer said it considered other options, including use of existing pads, but those were rejected because they would require greater travel distances from Pioneer operations and more frequent travel through the Kuparuk River unit. Offshore trenching for flowline Pioneer said it constructed two test trenches during March 2006 to refine engineering installation requirements for the sub-sea flowlines, one near shore and the other offshore near the drill site.
The flow-line bundle will be installed in the 2006-07 winter season using ice structures to support construction equipment, the company told regulators. Sea ice will be thickened by seawater flooding and spreading ice chips until the ice is grounded.
A slot will be cut in the ice and ice blocks removed. Flowlines will be welded and inspected and field joints coated and bundled with spacers and straps along the edge of the flow-line alignment. The trench will be excavated and the individual flowlines lowered into the trench. Power and communications cables will be installed in two parallel slots. The trenches will be backfilled and the lines hydrostatically tested before final tie-ins.
The five sub-sea cables include two fiber optic and three power distribution cables.
Pioneer said operational and design constraints required the change from the originally permitted design, which would have placed all cables in the same trench as the flowline.
Power and fiber optic cables have “restrictive handling characteristics at low temperatures” and design specifications can be met by keeping them warm and installing them quickly into trenches separate from the flowline. Pioneer also said there should be a reduction in the surface disturbance of the seabed in the flow-line trench by doing a faster installation without the bulky power cables. The company said it will install flowline immediately after a section of trench is dug, minimizing the time the trench is open.
The other advantage, Pioneer said, is that cable lay and flow-line operations can begin at opposite ends, creating a safer operating environment. The company said the one fiber-optic cable to be installed with the flowline bundle is relatively small and easy to handle.
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