PNA by Alan Bailey (NGP Photo). As Cook Inlet natural gasAlan Bailey, Petroleum News, Cook Inlet Gas Supply, Southcentral Alaska Natural Gas Supply, ENSTAR, Union Oil supplies tighten, with Southcentral Alaska utility Enstar Natural Gas Co. no longer having all of its needed gas supplies available under firm contracts, the commercial arrangements for the purchase and delivery of gas have become significantly more complex than in the heady days of excess gas availability.