ONEOK Inc., the parent company of Kansas Gas Service, announced Thursday it would buy back up to 7.5 million shares of company stock during the next two years.

The Tulsa, Okla-based ONEOK also announced a series of management changes, effective Feb. 1.

Sam Combs, president of Oklahoma Natural Gas Co., becomes president of ONEOK Distribution Cos., with responsibility for the operations of Kansas Gas Service, Oklahoma Natural Gas and Texas Gas Service.

Phyllis Worley, president of Kansas Gas Service, takes Combs’ place as president of Oklahoma Natural Gas. Brad Dixon, a Kansas Gas Service vice president, is moving into Worley’s role as president of Kansas Gas Service.

David Kyle, ONEOK’s chairman of the board, president and chief executive officer, announced the changes after markets closed Thursday.

Shares of Tulsa, Okla.-based ONEOK closed Thursday at $27.94, down 4 cents on the New York Stock Exchange.

“As ONEOK continues to grow, it is important that we make organizational changes to better manage and lead the company into the future,” Kyle said. “I am as excited about that future as I have ever been.”

ONEOK is an energy company involved in oil and gas production, natural gas processing, gathering, storage and transmission in the mid-continent region of the United States.

The company is the largest natural gas distributor in Kansas and Oklahoma, and the third-largest in Texas, serving almost 2 million customers.