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Borough project brings Barrow gas boost Barrow gas fields upgrade results in five new horizontal wells, new piping and a new control system for more reliable gas delivery By Alan Bailey Petroleum News
Most Alaska rural communities are suffering the pain of unsustainably high fuel costs. But for several decades the city of Barrow, at the extreme northwestern tip of the state, has enjoyed a plentiful supply of natural gas from nearby gas fields. Three fields — the East Barrow, South Barrow and Walakpa fields — currently supply gas to the city.
In the past winter the North Slope Borough conducted a major project to boost gas production by replacing aging infrastructure and drilling new wells in two of the fields, the East Barrow and Walakpa fields. The project involved a major sealift of equipment to Barrow, including the shipping of the Kuukpik No. 5 drilling rig from the Cook Inlet.
With the bulk of the work involved in the project complete, on July 25 Dudley Platt, oil and gas liaison for the North Slope Borough, described to Petroleum News how the project had progressed.
Success in primary purpose Platt said that full testing of the results of the project cannot be carried out until the coming winter, when relatively large volumes of gas can be flowed from wells for local consumption without any need for gas flaring. However, it is already clear that the project has succeeded in meeting its primary purposes to improve gas deliverability and bring additional gas reserves on line, as gas demand in Barrow gradually increases, he said. And with the production from new wells having the combined capacity to considerably exceed peak delivery needs in the winter, there is now sufficient excess production capacity to enable adequate production to continue in the event of any unanticipated future well problems.
“We can essentially meet the coldest day demand for Barrow with two of the Walakpa wells,” Platt said. Platt added that previously the shutting in of just a couple of wells in the three fields triggered the need for expensive backup diesel power generation.
“We’ve cured that problem,” he said.
One key to project success was the inclusion in the project team of a number of seasoned Alaska oil and gas professionals, Platt said. ASRC Energy Services, Tikiqaq-Conam, UMIAQ, Halliburton and Peak Oilfield Services worked on the project. Petrotechnical Resources Alaska was the lead consulting firm, designing the new wells and representing the borough during the drilling operations. Kuukpik Drilling provided the rig and crew.
Five horizontal wells The borough envisioned the drilling of up to six wells, all of them horizontal wells that would thread through the gas field reservoir sands, with two of the wells in the East Barrow field and four in the Walakpa field. In the event, the team succeeded in completing five wells: both planned wells, the Savik 1 and Savik 2 wells, at East Barrow, and three wells, the Walakpa 11, 12, and 13 wells, in the Walakpa field.
The horizontal components of the Savik wells attained lateral lengths of 1,219 to 1,415 feet at vertical depths of 2,037 to 2,065 feet, while the lateral lengths of the Walakpa wells were 1,286 feet to 2,033 feet at vertical depths of 2,358 feet to 2,387 feet.
Also as part of the gas field refurbishment, the team upgraded aging gas pipelines and installed modern wellhead housing. A major reason for upgrading the pipeline from the East Barrow field was to enable an increase in gas pressure in that line, thus enabling higher gas delivery rates from East Barrow when maintenance is taking place at Walakpa.
And an upgrade to the computer and communications system that controls and monitors field production now allows wells to be opened up or closed remotely, in addition to collecting information such as gas pressures and temperatures, Platt said.
Started in September With the East Barrow field being accessible by road from Barrow, drilling started there in early September, the plan being to build an ice road to the Walakpa field, some miles to the south of Barrow, once winter conditions permitted.
And the first well at East Barrow, the Savik 1, proved something of a learning experience, with large quantities of clay from a zone above the field reservoir gumming up the drilling equipment at times during the drilling operation. The clay, with a consistency and weight akin to the modeling clay used in school classrooms, had to be collected in bags and tested for appropriate disposal, Platt explained.
However, although the Savik 1 well was finished a bit later than planned, the drilling team succeeded in drilling the second well more quickly, Platt said. Ice-road construction to Walakpa took place within an acceptable time frame.
And overall the project succeeded, despite having to contend with some fairly atrocious weather conditions — heavy rain and accompanying mud in September and October were followed by severe cold as the winter closed in.
“The temperatures … for a third to a half of the entire drilling project were at 50 degrees below zero,” Platt said.
Old wells plugged In addition to drilling new wells, the team plugged and abandoned eight old wells, drilled many years ago by the U.S. Navy. A ninth “legacy” well that is accessible by road remains to be plugged, Platt said.
And the North Slope Borough is obtaining the use of a coiled tubing unit to clear a blockage from a suspected downhole gas hydrate plug in the Savik 2 well. The drilling of that well was successful and the well encountered anticipated reservoir gas pressures, but a mechanical constriction within the well has thus far prevented gas production from it, Platt said.
The borough is also going to plug and abandon the East Barrow 15 well, the well that was used for the disposal of drilling waste during the course of the project, he said.
The borough takes particular pride in the achievement of successfully drilling five horizontal wells in challenging conditions, with no significant health or safety issues, in a project that has cost to date a bit less than $100 million, Platt said.
“We’ve just proved that a little local government can go out and do oil and gas development on highly sensitive Native lands, with subsistence issues out there,” Platt said. “And we proved we could do it using the same care and standards that we expect out of any oil and gas company.”
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