Anadarko Petroleum received clearance from federal regulators on Tuesday to take over Western Gas Resources Inc.

The Houston-based firm is one of the world's largest independent exploration and production oil companies. It acquired both Western Gas Resources and Kerr-McGee for a combined value of $23.3 billion. The Kerr-McGee acquisitions was approved by the federal anti-trust regulators last week.

In a press statement, Anadarko expected the transaction for both companies to '˜close as soon as practically possible' subject to shareholders approval.

The acquisition of both these companies would enable Anadarko to be one of the industry leaders in the North American gas fields that contains low risk of government intervention. This transaction would enable the firm to control 2.6 million net acres of gas fields and achieve cost synergy between the merged entity through sharing resources and skills. The firm's North American operation would be strengthened by this purchase, but the firm had to assume a debt of $22 billion to fund the acquisition.

"Two years ago, we unveiled a strategy that included a solid North American foundation of onshore resource plays', Anadarko Chairman, President and CEO Jim Hacket said. "Kerr-McGee and Western Gas Resources...enable us to create a more focused operating strategy with a larger and lower-risk asset base.'

The firm acquired the two companies to obtain technological skills and expand nationally. In Kerr-McGee's case it was because of its deepwater holdings and skill sets that would elevate Anadarko into the top echelon of deepwater operators. In addition to the skills, the two companies would enable the firm to expand into Colorado, Utah and Wyoming.