FTSE 250-listed Riverstone Energy has, in partnership with Liberty Resources II, completed the acquisition of oil and gas assets in North Dakota's Williston Basin.The $446m purchase was funded through equity investments from funds managed by energy private equity firm Riverstone Holdings, Liberty II management and other investors, as well as third-party debt. Riverstone Energy, which is one of the managed funds, contributed $66.4m, including its $13.3m share of the deposit funded on January 30th. The acquisition comprised around 53,000 net acres and over 4,000 barrels of oil equivalent per day day of production from the Bakken and Three Forks formations, which Liberty will continue to target as it furthers the development of the acquired properties. The transaction is the first acquisition by Liberty since its formation in November last year. Its Chairman and Chief Executive, Chris Wright, said: "Over the past two years, Liberty's unique completions approach has consistently demonstrated the highest average production rates of any operator in the Bakken formation. "This acquisition provides us with exposure to highly attractive areas of the basin where we have not previously operated and where we hope to achieve similar operational success as that achieved during our team's prior venture."NR