Natural gas producer and distributor Williams Cos. on Thursday said it has agreed to sell its 74.9 percent interest in its Four Corners gas-gathering business to minority owner Williams Partners LP for $1.22 billion.

The partnership originally acquired a 25.1 percent stake in Williams Four Corners LLC from Williams for $360 million in June 2006. Williams spun off Williams Partners in 2005 but retains a majority stake.

The Four Corners business is located in the San Juan Basin of New Mexico and Colorado and includes about 3,500 miles of gathering lines and five natural gas processing plants. The system has capacity to collect 2 billion cubic feet of gas per day.

Williams Partners expects the deal to immediately boost cash flow. The company expects to finance its purchase evenly split between debt and equity.

The transaction is expected to close by the end of the fourth quarter, subject to closing conditions.

Williams Four Corners LLC earned $113.5 million in 2005.