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CINGSA reflects on first year of use New Kenai Peninsula gas storage facility provided an essential service for Southcentral utilities in bolstering winter gas supplies Alan Bailey Petroleum News
In a plan of development, filed with the Alaska Department of Natural Resources in January, Cook Inlet Natural Gas Storage Inc., operator of the new natural gas storage facility on Alaska’s Kenai Peninsula, reflected on its experiences during 2013, the facility’s first full year of operation. The facility, generally referred to as CINGSA, provides gas storage facilities for several Southcentral Alaska gas and power utilities and performs an essential role in ensuring that excess gas produced in the summer from the Cook Inlet basin can be stored for use in the winter, when utility gas demand peaks. Without the facility, the utilities would have run short of gas during periods of cold weather during the current winter and the winter of 2012-13.
The facility stores gas in a depleted reservoir in the Cannery Loop gas field to the south of the city of Kenai. Five gas wells at the facility can both inject gas into the reservoir for storage and produce gas from the reservoir at times when gas is needed. The facility has a maximum capacity of 18 billion cubic feet of gas, with 11 billion cubic feet potentially available for withdrawal and with the remaining 7 billion cubic feet used as base gas, to maintain the pressure in the underground reservoir.
Started April 2012 CINGSA first began injecting gas into the reservoir in April 2012, in preparation for making gas available from the facility during the following winter. Gas withdrawals started on Nov. 9, 2012, although the facility did not acquire its full quota of base gas until March 31, 2013, the development plan says. In January 2013 the facility had 11.5 billion cubic feet of gas in storage. Over the course of 2013 CINGSA injected 6.3 billion cubic feet of gas into the reservoir. The company withdrew 3.1 billion cubic feet for its customers over that same time period, leaving 14.3 billion cubic feet in storage at the end of the year, the development plan says.
The development plan says that, following some early disappointment with gas injection rates, CINGSA re-perforated all of the facility’s wells. The remedial work substantially improved the well performance, although the performance does remain below design capability, the development plan says.
Pressure testing CINGSA performs a scheduled shutdown twice a year to conduct pressure tests in the reservoir, and to analyze the mass balance of gas in the facility, to verify that the reservoir is not leaking. During a test of this type, conducted between Oct. 28 and Nov. 4, 2013, pressure readings indicated that, with the reservoir filled with gas ready for the winter, the reservoir pressure may have exceeded the maximum of 1,700 pounds per square inch approved by the Alaska Oil and Gas Conservation Commission.
CINGSA has been corresponding with the AOGCC on how to resolve the pressure issue and prevent a recurrence. The development plan comments on the difficulties of determining the reservoir pressure, given the time that it takes for gas to permeate the reservoir and hence the time lag between gas injection and the stabilization of the gas pressure across the reservoir. Although the downhole pressure in the well used to take the pressure measurements suggested a reservoir pressure 30 pounds per square inches above the permitted limit, the pressure across the reservoir may have settled at a pressure below the limit after sufficient time elapsed for pressure stabilization, the plan says.
However, CINGSA plans to apply to AOGCC to allow the reservoir to operate at a higher maximum pressure, but at a pressure less than the 2,200 pounds per square inch in the reservoir when the Cannery Loop gas field was first discovered, the development plan says. The plan says that CINGSA does not currently have any firm plans to expand the capacity of its facility.
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