Miller is selling its Tennessee assets in the Appalachian Basin's Mississippi Lime and Chattanooga Shale plays through PLS Inc.
Shale plays and foreign investors are essential to spurring growth.
WPX said it expects the JV to generate returns comparably to the company’s oily projects.
Analysts said the company picked up solid territory with the $252 million acquisition.
Tug Hill currently operates in Kansas with 800,000 leased acres targeting the Mississippian Lime Formation.
BP led the pack, with the sale drawing nearly $110 million in high bids.
First-half 2014 sees nearly a dozen billion-dollar deals and natural gas assets gaining favor.
Several independent E&Ps are finding other ways to expand their territories in pricey plays.
Sluggish deal activity in 2013 is showing signs of turning around.
Much of private equity's success can be attributed to its uncanny ability to buy when no one else has capital, according to one analyst.
The sale continues Cameron's trend of streamlining its industrial and strategic focus, analyst says.
The deal increased Ultra’s Pinedale holdings to 68,600 net acres and operatorship to 82%.