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Badami restart: Savant plans to bring six wells on line in
BP-operated North Slope unit
The off-again, on-again story of BP’s troubled Badami oil field, the most easterly of the developed fields on Alaska’s North Slope, continues with a planned field restart in September. For the past two years independent oil company Savant Alaska and Arctic Slope Regional Corp. have been partnering with BP to bring new life into the field, with Savant drilling a new horizontal sidetrack well that may entice oil to flow more readily from the field’s challenging reservoir, and also drilling an exploration well into another, deeper oil pool within the Badami unit.
Six wells In the field restart, Savant anticipates bringing six wells into production, including the new horizontal well and the exploration well, Savant executive Greg Vigil told Petroleum News Aug. 24. Combined production from all six wells is projected at more than 4,000 barrels per day, Vigil said.
Savant drilled the exploration well, B1-38, in February of this year in the Red Wolf prospect and found oil in two horizons, with one of the horizons being in the Kekiktuk formation, the formation that contains the oil reservoir for the Endicott field, some miles to the west. But the oil production starting from the well in September will be from the late Cretaceous Killian sands, a discovery in a secondary exploration target at a higher level than the Kekiktuk, Vigil said.
Paperwork filed with the Regulatory Commission of Alaska for the restart of the Badami pipeline that carries Badami oil to the northern end of the trans-Alaska pipeline indicates that BP will start filling the line with oil from the Endicott field at around Sept. 1, with a view to restarting the Badami field on Sept. 5. But BP spokesman Steve Rinehart told Petroleum News Aug. 23 that it may be mid-September before field production finally gets underway.
“Savant’s success is good news,” Rinehart said. “We are pleased that this is leading to the restart of the Badami processing facility. We are aiming for mid-September, as we continue to inspect facilities and bring the plant online.”
The mid-September timeframe takes account of minor glitches in the startup program, including some weather induced work delays and problems with a stuck pig in the Badami pipeline, Rinehart said.
Field crews are working their way through a list of field startup items and the main power turbine for the field facilities is now up and running, Rinehart said — in June BP notified RCA that it planned to ship natural gas by pipeline from Endicott to Badami, to power the Badami facilities until gas production from Badami becomes available.
Disjointed reservoir The on and off story of Badami reflects the mixed results of oil development in the sand reservoirs of the Brookian sequence, the youngest and shallowest of the petroleum-bearing rock sequences of the North Slope. The Brookian reservoirs are typified by rocks called turbidites — interlayered sands and impervious shales formed by the flow of mixtures of sediment and water down the sloping sides of deep marine basins.
At Badami, the turbidite sands fill ancient channels aggregated in distinct lobes, charged with oil but isolated from one another in such a way that oil cannot flow freely through the entire field reservoir. Initially, oil tends to flow at a good rate into an individual production well as individual sand channels are drained, but production then drops off as barriers between the channels and lobes inhibit the drained sand from recharging, a problem compounded by the somewhat viscous character of some Badami oil.
Disappointment BP originally placed the 120-million-barrel field on line in August 1998 amid euphoria about bringing a new Brookian oil play into commercial production. But that euphoria sank about as fast as the subsequent decline in oil flow through the Badami pipeline.
Initial production, anticipated at 30,000 barrels per day, actually came in closer to 18,000 barrels per day and dropped to less than 3,000 barrels per day by early 1999. Faced with unsustainable pipeline flow rates in winter conditions, BP subsequently shut the field in between February and May 1999.
And after restarting the field BP used gas injection to try to force more oil up the production wells and unsuccessfully tried the drilling of lateral wells from the original well bores to further boost production.
Field suspension By March 2003, with oil trickling down the Badami pipeline at the rate of 1,400 barrels per day, BP was considering options for selling the field. And in August of that year, as production continued to fall, the company finally suspended field operations, placing the field facilities in warm shutdown for two years.
The field duly came back on line in 2005, but production continued at rates not much above those before the 2003 shut in. And in 2006 BP said that it was now considering the use of horizontal wells to improve production rates by increasing the reservoir volume exposed to each well bore.
But in September 2007 BP shut the field in again, to allow the reservoir to recharge.
New partnership In 2008 Savant and ASRC formed a deal with BP in which Savant would drill the new development well and exploration well that are now scheduled to come on line. The development well is presumably testing the potential for horizontal drilling to finally unlock economic levels of sustained production in the field.
“We are optimistic that this will be the beginning of a long-term production period for the Badami unit,” Vigil said, in reflecting on the September 2010 restart of the field.
—Alan Bailey
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