Apache said the $3.75 billion deal with Fieldwood Energy LLC involves more than 500 blocks in 1.9 million net acres in the gulf.
Fieldwood said current daily production from the acquired reserve area is more than 95,000 barrels of oil equivalent. Chief Executive Officer Matt McCarroll said his company was "very enthusiastic" about carrying Apache's legacy forward.
Apache Chairman G. Steve Farris said the divestment gives the company a chance to balance its portfolio.
"Since 2010 we have increased our focus in North America on capturing and developing a deep inventory of onshore assets, where we have been generating exceptional production growth at attractive rates of return," he said in a statement Thursday.
Apache last year ran into a major oil discovery while drilling in the deep waters off the southern U.S. coast in the Green Canyon reserve area.
"Apache has had a great run on the Gulf of Mexico Shelf over the last 30 years, and the Shelf region and staff have played a vital role in making Apache the company it is today," Farris said.