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Working interest owners submit Point Thomson development plan ExxonMobil says Thomson sands gas cycling will be basis of development, Brookian oil rim development may follow, but not economic now Kristen Nelson PNA Editor-in-Chief
After years of studying Point Thomson development, major owners at the eastern North Slope field bordering the coastal plain of the Arctic National Wildlife Refuge have determined that Point Thomson has the potential for economic development and have initiated the permitting process.
“Preliminary economic analyses indicate the potential for commercial development and the owners have decided to initiate the permitting process,” unit operator ExxonMobil Production Co. said in a draft of the 18th plan of development (October 2001 through September 2002). ExxonMobil told the state that field owners will spend $35 million over the next two years in the permit process and doing preliminary engineering. One goal of work in the next year, ExxonMobil said, is to continue with economic evaluation and move the project toward sanction — development approval from the owner companies.
The gas cycling project will develop the natural gas hydrocarbon condensate in the Point Thomson sands. There are also Brookian-age oil accumulations at Point Thomson, but ExxonMobil told the state that it is questionable if the Brookian-age oil is economic at this time and the current project scope doesn’t include the Brookian. Offshore development options rejected All facilities for the Point Thomson development — except a barge dock — would be land based.
ExxonMobil said in the environmental report that three field development options were identified: drilling pads on existing offshore barrier islands; drilling pads on offshore man-made gravel islands in Lions Lagoon; and drilling pads onshore.
All of the options sited the facility pad onshore.
The offshore barrier islands were rejected because the islands are not optimally located to reduce average well length, ExxonMobil said. A drilling pad on Flaxman Island would have required at least one additional western onshore or offshore well pad to develop the reservoir. And based on reservoir geography, shoreline locations were better positioned than Flaxman Island to tap the eastern end of the reservoir — and gravel islands were better positioned than Alaska and Challenge islands to tap the western end.
The prospective environmental impacts of drilling from barrier islands were also greater due to waterfowl nesting and polar bear habitat.
The man-made gravel island option was rejected because subsea pipelines would have to bring three-phase steam fluid to shore and the high temperature would increase the complexity of pipeline design and maintenance. The lagoon is also, ExxonMobil said, a foraging and molting habitat for waterfowl nesting on Flaxman Island and there is bear denning which could potentially be disturbed by construction in the lagoon.
The target reservoir is assessable from onshore drilling pads with extended reach drilling, ExxonMobil said. ERD wells to 20,000 feet will help minimize the number of drilling pads and will also reduce the number of marine docks as no island docks will be required. Wells to 13,000 TVD Wells will be drilled to a vertical depth of approximately 13,000 feet and ERD drilling will reach targets extending out to 20,000 feet. Production and injection wells will be large bore with 7 inch nominal diameter tubing. Two rigs will be used for drilling. ExxonMobil said they would likely be mobilized to Point Thomson by barge, although they could also come over a seasonal ice road from Endicott.
The east well pad would be in 9N-24E, UM; the central well pad, facilities and dock in 9N-23E, UM, and the west well pad in 10N-22E, UM. ExxonMobil said there was also the potential of an additional production well pad in the far west, approximately 3-6 miles farther to the west than the west well pad.
The east and west well pads would each be about six acres in size. The east well pad would have seven producing wells and space for two future wells; the west well pad for have six producing wells and space for two future wells.
The central well pad, including a portion of a 50-foot dock road, would be 15 acres and would have eight injection wells and one disposal well, with room for two future wells.
The central production facilities pad, including portions of the 50-foot dock road, would be 21 acres. There would also be a gravel storage pad and maintenance stockpile.
The potential additional far west pad would be approximately five acres and accommodate four to six wells. Sea ice road from Endicott A 42 mile sea ice road along the shore from Endicott would be built using seawater and a fresh water cap. It would be needed for two construction seasons and on occasion thereafter depending on logistics and special projects. The sea ice road would be used to transport heavy equipment, materials and supplies during drilling and construction phases.
Land ice roads would be built during the first two constructions seasons, in the first winter a 3-mile land ice road would be built to a fresh water source. In the second winter land ice roads would be built along the pipeline right of way.
Permanent gravel all weather roads will connect the well pads, airstrip, gravel mine and fresh water supply to the central processing facility pad.
The dock will be used for delivery of drilling rigs and major sea lifted facility modules, and for large quantities of bulk materials during construction, drilling and operations. ExxonMobil noted that the 750 feet by 100 foot dock is also important for spill response capability. Elevated gathering lines There will be elevated gathering lines constructed of corrosion resistant alloy to carry the pressurized three-phase stream to the central processing facility where gas, produced water and hydrocarbon condensate will be separated. A 22-mile elevated carbon steel pipeline will transport the stabilized hydrocarbon condensate — which is, ExxonMobil said, non-corrosive — to connect with the Badami pipeline.
Gas turbine driven injection compressors at the central processing facility will re-inject lean gas into wells at the central well pad.
The project also has “the potential to accommodate limited production of heavy oil from the Point Thomson oil rim,” ExxonMobil told the state.
There is also the potential for gas sales.
“Depending on the sales pipeline route and sales gas specifications, additional Point Thomson facilities would be required to accommodate gas sales including gas dehydration, gas pipelines, and/or gas treating/conditioning facilities.”
But ExxonMobil said it is questionable if Brookian-age oil is economic at this time. And the current project scope doesn’t include Brookian. 75,000 BPD Production could be as high as 75,000 barrels per day “for the three-train case” ExxonMobil said, and production could last for as long as 30 years.
The Point Thomson sands reservoir targeted in this development is onshore and offshore Lions Lagoon about 20 miles east of Badami.
The high-pressure gas reservoir at Point Thomson was discovered in 1973 and is estimated to contain more than 8 trillion cubic feet of gas and more than 200 million stock tank barrels of recoverable concentrate.
ExxonMobil said that condensate is the hydrocarbon liquid that condenses from the 3-phase stream as the stream is expanded from the high-pressure, high-temperature reservoir conditions to the lower pressure, cooler conditions in the surface gathering and processing facilities.”
Clean, pure condensate is a clear liquid, but ExxonMobil said that Point Thomson condensate is expected to be cloudy to light brown liquid as it will contain small amounts of sediment and water (less than 0.35 percent combined) and small amounts of other liquid hydrocarbon constituents.
The central processing facility will gather and process the three-phase steam from the drilling pads on the east and west sides of the field and gas, water and hydrocarbon condensate will be separated. Lean gas will be re-injected into the formation at the central well pad near the central processing facility. Produced water will be reinjected into a disposal well.
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