Private-equity juggernaut Kohlberg Kravis Roberts & Co. LP, leading a consortium of financial partners including Natural Gas Partners, Crestview Partners and Itochu Corp., is set to acquire 40-year-old, privately held Tulsa, Okla.-based Samson Investment Co. for $7.2 billion.

The investor group will acquire all of Samson’s assets, excluding onshore Gulf Coast and offshore deepwater Gulf of Mexico assets, which will be retained by the Schusterman family, which owns Samson.

Samson, founded in 1971 by Charles Schusterman, is one of the largest private E&Ps in the U.S. It owns interests in more than 10,000 wells and operates some 4,000 wells across 18 states. It holds positions in the Bakken, Powder River, Green River, Granite Wash, Cana Woodford, Cotton Valley, Haynesville and Bossier plays, and has 1,200 employees with offices in Houston, Denver and Midland, Texas. Annual capex exceeds $1 billion.

Samson chief executive Stacy Schusterman, daughter of the founder, says the company specifically sought a partner that would value both the company’s assets and its people. The buyer group will keep company headquarters in Tulsa. Current Samson chief operating officer David Adams will become chief executive officer, and the company will be renamed Samson Resources.

KKR has also hired Claire Scobee Farley and David Rockecharlie as managing directors of oil and gas investments. Farley and Rockecharlie, both formerly with Jefferies, formed RPM Energy LLC to match energy investors with investments, backed by KKR.

Bank of America Merrill Lynch, Barclays Capital Inc., BMO Capital Markets, Citigroup Global Capital Markets Inc., Credit Suisse, RBC Capital Markets, Tudor, Pickering, Holt & Co. LLC, and Wells Fargo Securities LLC are financial advisors to KKR, NGP and Crestview. Mizuho and Evercore Partners are financial advisor to Itochu Corp. Jefferies & Co. Inc. is financial advisor to Samson. Simpson Thacher & Bartlett LLP is legal counsel to the investor group, and Dallas-based Jones Day is legal counsel to Samson.

The deal was expected to close by year-end 2011. (For more on the Sam-son acquisition, see “Private Equity’s Big Reach” in this issue.)