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NYC 9/11 Public Portal Document

Water Supply Operations & Maintenance DESALINATION SUBSEA INTERVENTION TOOL SAVES GETS NEW RESPECT BY REPLACING COSTLY SOLVENT LINE ONCE CONSIDERED A COSTLYWHUE ELE- phant, seawater desalination is getting a vote of confidence Jfrom water officials in Southern California. Two major agen­ cies this month are taking strides toward bringing plants on line by mid-decade. Umbilical reel The Metropolitan Water District of Southern California, a cooperative serv­ ing 17 million people in six counties, 3 announced Dec. 4 that it is seeking pro­ posals to produce up to 50,000 acre-ft of desalinated ocean water per year—effec­ tively 45 million gallons per day—at one or more plants. Public-private parmer- ships must include at least one of Los \ Angeles-based MWD’s 26 member agen­ cies. MWD says it will subsidize up to $250 per acre-ft of potable water. The agency Subsea \ Subsea now supplies about 4 million acre-ft an­ \ Intervention umbilical nually, paying $431 per acre-ft for the half Intervention tool of the total imported from northern Cal­ Remotely ifornia and the Colorado River. operated vehicle 1 On Dec. 6, the San Diego County Wa­ ter Authority approved a feasibility study Y by PB Water, a unit of New York City-based Flowline Parsons Brinckerhoff Inc., for a 50-mgd desalination plant in Carlsbad. This facil­ end manifold ity would be the largest of its kind in the western hemisphere, says Walter Wmrow, Flowline to facility— Engineering Services, Inc. ' executive vice president in the San Die­ go office of Poseidon Resources Corp., ONE-SHOT WONDER Tool Is good for one or two Interventions In emergencies. the project’s developer. Winrow declines to speculate on the cost, but this year BY MODIFYING A TOOL TO ASSURE PRO- flowline. Insulation and others, are de­ Poseidon awarded a $75-million turnkey I duction flow from deepwater subsea oil signed into a production system, he says. contract to Ogden Water Systems Inc., 1 1 and gas wells, a major Guff of Mexico He describes the flow-assurance tool as Fairfield, N.J., for a 25-mgd desalination producer has saved money on design of “a prudent insurance policy,” somewhat plant in Tampa Bay, Fla. (ENR10/16/00 1 i a system entering production this month, like having a fire extinguisher available. p.46). Standardizing wellhead design to use the The lO-ft-taU, 8,000-lb tool normally Lower costs linked to the refinement ! new tool will allow the savings to be re- will be stowed on a service vessel and low- of reverse-osmosis technology are making peated on future wells. ered to the sea floor and connected to seawater desalination more attractive, The subsea intervention tool was the flowline manifold when needed. Ac- water officials say. Although costs once designed by Paragon Engineering Ser- tuated by a remotely operated vehicle, it hovered near $2,000 per acre-ft, “Talk out vices Inc., Houston, for Shell Explora- wiU allow process fluids and chemicals to there is along the lines of the $1,000 tion & Production Co., New Orleans, to be fed through the umbilical to restore range and lower,” says Anatole Falagan, remediate flowline blockages at Shell’s the line’s flow. The tool then will be dis- assistant manager of MWD’s water re­ Serrano and Oregano fields. Blockages connected and retrieved to the vessel. source management group and manager can form under certain temperature and Salter declines to give the cost of the of the desalination REP program. Water pressure conditions. An earlier version tool but calls it an insignificant part of costs for the Carlsbad plant are estimated 1 was installed on Shell’s Mensa produc- the combined capital cost of more than at $794 per acre-ft, says Ken Weinberg,

i tion system in the mid-1990s. But where the Mensa system’s tool remediated only hydrate blockages, the SerranoOregano $250 million for both fields. Having it available allows the system to be designed without a separate 2-in. line or umbilical SDCiWA’s director of water resources. spCWA staff plan to make a recom­ mendation on the Carlsbad proposal in tool also can remediate asphaltene and from the production platform eight miles January. Initial letters of intent to respond paraffin block^es. away that would be required for solvent to MWD’s request for proposals are due A flowline blockage can defer pro- injection to dissolve asphaltene deposi- by Feb. 14 and the agency will make a duction for several months, says Sean lions. Because Shell has standardized well- decision in June, says Falagan. Teams Salter, Shell’s Serrano-Oregano project head design to accommodate the tool, would be required to start construction execution team leader. Primary defenses all future subsea wells will have the same within two years of being awarded the con­ I against blockages, including the type of capability. □ tract, he says. □

December 17, 2001/ENR 17

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