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CPAI plans summer dredging at Oliktok Work lowers seafloor to ease intake of water to treatment plant; water from plant aids re-injection efforts at Kuparuk, Alpine Eric Lidji Petroleum News
ConocoPhillips plans to remove a chunk of sea floor in the Beaufort Sea this summer to aid the treatment of water used for oil production at two Alaska North Slope fields.
The natural rise in sediment on the seafloor north of Oliktok Point threatens to clog the Kuparuk Seawater Treatment Plant used to process seawater for re-injection into oil fields in the Kuparuk River the Colville River units.
When ARCO built the treatment plant, the seafloor north of Oliktok Point sat eight to nine feet below sea level. The seawater intakes at the treatment plant sat several feet above the seafloor, allowing enough room for things like twigs, gravel and other underwater matter to fall to the bottom and not clog up the system.
In the years since initial construction, natural currents have pushed additional sediment in front of the treatment plant, raising the seafloor. Now, the seafloor in front of the treatment plant sits about six to eight feet below sea level, crowding the underwater currents and funneling unwanted material to the facility, restricting seawater intake.
ConocoPhillips attempted to correct this problem over the years by building weirs and screens, but said these can only be used in the summer.
“Natural seabed sedimentation processes has now progressed to the point that maintenance dredging of the area is necessary for continued safe operation of the facility,” the company wrote in its operations plan for the project.
Moving 7,000 cy of sediment Starting around mid-June or July this year, ConocoPhillips will remove around 7,000 cubic yards of sediment and seafloor from a 300-foot wide and 500-foot long area in front of the facility. The goal is to get the seafloor back down to nine feet below sea level.
The company will place the material along a concrete embankment along the west side of the facility, which sits on a spit protruding from the tip of Oliktok Point.
To move the material, ConocoPhillips will use a suction dredge mounted to the front of a boat, and may also have to use a barge to excavate the detritus gathered in front of the facility. The company does not believe it can do the work from the shore.
ConocoPhillips hopes to wrap up the project by September, but the company might have to spread the dredging over two summers if it can’t complete the work within the thin window of time when the Beaufort Sea is free of ice.
The Kuparuk Seawater Treatment Plant sucks in water from the Beaufort Sea, treats and filters it and sends it through supply pipelines to injection wells at Kuparuk and Alpine. The filtered water is pumped into existing reservoirs to maintain pressure and improve oil recovery at the fields.
The project is currently sitting with the state Division of Ocean and Coastal Management, which will accept comments on the plan through June 23.
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