Farmington Hills, Mich.-based Semco owns Enstar Natural Gas Co. and Alaska Pipeline Co. owns and operates the high-pressure gas pipelines that transport gas from Alaska's Cook Inlet gas fields to Enstar's distribution system and to various commercial customers of Enstar. Enstar serves 112,000 customers in Southcentral Alaska, including Anchorage.

Semco said Alaska Pipeline has no employees and Enstar is its only customer; the sale is structured to have no effect on Enstar customers or employees.

Enstar will purchase all of Alaska Pipeline Co.'s gas transmission capacity for at least 10 years and will operate the company's pipelines for a minimum of five years. There are no plans to change rates, services offered, pipeline operations, customer service, gas supply or staffing as a result of the sale, Semco said.

The sale is subject to various regulatory approvals, including that of the Regulatory Commission of Alaska.

Marcus Jackson, Semco Energy's chairman, president and chief executive officer, said in a statement that proceeds of the sale will be used to "pay down debt in order to improve the financial position and thus the long-term value of the company."

Atlas Pipeline Partners owns and operates natural gas pipeline gathering systems through its operating partnership and its operating subsidiaries. The Moon Township, Pa.-based Atlas was formed to acquire natural gas pipeline gathering systems. Its primary asset is 1,380 miles of intrastate gathering systems in western Ohio, western New York and western Pennsylvania.