Drivers on Kenai’s Bridge Access Road during the past few weeks might have noticed a crane rising above the trees opposite the intersection with Beaver Loop Road.
The crane, sitting on the gravel pad of the Cook Inlet Natural Gas Storage Alaska facility was lowering coiled tubing into one of the pad’s five gas wells to remove a sand buildup blocking it — the first such problem since CINGSA’s 2012 opening, according to CINGSA communications manager Lindsay Hobson.
A dehydration unit — which removes liquid compounds that come from the ground mixed with methane, the combustable ingredient of natural gas — also failed recently, Hobson wrote.
In response to these problems, CINGSA might add backup dehydration units and drill new wells. The five it currently uses date from the facility’s construction.
Though CINGSA’s wellheads are at the Beaver Loop-Bridge Access intersection, the bulk of the gas storage facility is roughly 6,690 feet underground in a sandstone slab — known as the the Cannery Loop Sterling C pool — beneath the Kenai River flats. Marathon Oil previously extracted naturally-occurring gas from the formation’s sandstone pores, but after declining production from Cook Inlet’s gas fields threatened shortages — potentially leading to power and heating outages — in the late 2000s, the field was put to a new use: holding gas pumped in during the summer when heating demand is low, and distributing that gas in the winter when the demand is higher.
CINGSA’s 11 billion cubic feet of storage capacity have since become important for heating and powering south central Alaska through the winter. Hobson wrote that January 2017 was a record month for the facility’s gas withdrawals. CINGSA supplied about 30 percent of the gas moved around the Cook Inlet region that month, and on one particular day — Jan. 19, 2017 — it supplied 44 percent of the demand for regional gas utility ENSTAR, Hobson wrote.
ENSTAR and CINGSA are both owned by the Michigan-based Semco Energy and share some staff, including Hobson. In addition to ENSTAR, CINGSA’s storage clients are the power utilities Homer Electric Association, Chugach Electric Association and Anchorage’s Municipal Light and Power, which fuel most of their electrical generation with natural gas.
Though the possibility that sand will plug up a gas well is “a constant risk to any storage facility,” Hobson wrote, this is the first time it’s happened to CINGSA.
“When a part of the facility goes down the potential impact can be far-reaching,” Hobson wrote. “… Even though (the blocked well clean-out) was considered a ‘maintenance event,’ had this happened during an extreme cold weather event, the utilities may have faced a gas shortage out of CINGSA.”
Hobson wrote that CINGSA employees began to notice declining output from the pad’s Well Number 3 in March, and that it eventually led to “a 20 percent drop in CINGSA’s capacity.” Fortunately spring is a “shoulder season” for CINGSA, Hobson wrote — utilities are decreasing their withdrawals as winter demand declines, and gas producers don’t yet need to inject the excess supply they may have in the summer.
“The timing was fortunate in that this occurred when customer needs were in transition,” Hobson wrote. “Had this occurred in January or June, service to CINGSA customers would most likely have been affected.”
The Alaska Oil and Gas Conservation Commission approved the work on March 30, and CINGSA’s contractor, Schlumberger, finished it Monday. It consisted of running a coiled tube to the bottom of the well “then washing it down with foam and nitrogen,” wrote CINGSA vice president John Lau to the Alaska Oil and Gas Conservation Commission. The recovered fluid was stored in a tank, and gas produced during the work was vented or flared.
Reach Ben Boettger at email@example.com.