The assets being acquired represent the largest operated asset base on the Gulf of Mexico Shelf and include more than 500 blocks and 1.9 million net acres.
The deal came a month after Riverstone closed its latest power and energy fund above its $7.5bn hard cap.
At the end of 2012, the assets were estimated to hold 239 million barrels of oil equivalent and are currently producing more than 95,000 barrels of oil equivalent per day.
Fieldwood and Apache have also agreed to participate in deep exploration opportunities on the acquired assets.
Riverstone said the deal presented “a unique opportunity to acquire a successful business of scale with a strong partner we know well and the proven professionals who have built this business over many years.”
Riverstone partner Pierre Lapeyre said, “We have had a long-standing and strong relationship with Apache’s executive management and have been great admirers of their entire organization and their Gulf of Mexico operations for many years.
“The Gulf has been a core area of focus of ours since our early funds, and we couldn’t be more pleased to have the opportunity to partner with the combined Fieldwood and Apache Gulf teams in this rare and exciting new opportunity.”
Earlier this month Riverstone partnered with midstream logistics company Bridger to invest up to $300m in the company’s growth strategy.
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