A four-year, $400 million joint venture (JV) between EOG Resources Inc. (NYSE: EOG) and The Carlyle Group LP (NASDAQ: CG) will develop oil and gas wells in Ellis County, Okla.

After unspecified performance hurdles are achieved in the program, Carlyle’s working interests will largely revert to EOG, the private-equity firm said. The wells are likely to target the Marmaton Formation.

The size of the JV makes it unlikely to materially affect EOG’s plans in the Permian, Eagle Ford and Bakken—areas where it most of its capex, budgeted at up to $4.1 billion.

Since December, the company has filed several permits in Ellis including some in early May for horizontal wells that target the Marmaton Formation.

Tudor, Pickering, Holt & Co. (TPH) said four rigs are running in Ellis between FourPoint Energy and Jones Energy (NYSE: JONE).

“Though the Cleveland has historically been the primary target in this region, the JV will be focused on the Marmaton, a horizon with limited well control,” TPH said. “Given EOG’s operational track record, we would expect to see a step change in proppant loading/stage spacing with a focus on targeted laterals to enhance capital efficiency.”

TPH said it does not provide any credit for the asset and expects it to be “at the bottom of the totem pole for near/medium term capital allocation.”

Upcoming well results from the JV could give a meaningful bounce to neighboring Apache Corp.’s (NYSE: APA) assets, “given their sizable footprint in the region.” TPH considers the asset a potential candidate for divestment.

In 2011, EOG reported that it held a 34,000-net acre position in the formation and had drilled and completed a series of wells. No other mentions of the acreage’s performance were available on EOG’s website. Since 2012, about one-tenth of active wells in the county have gone idle, dropping to 970 in 2015 from 1,093 in 2012.

Vinson & Elkins advised The Carlyle Group LP in its definitive agreement to fund the development of EOG’s oil and gas assets in Ellis County. As part of the JV, Carlyle Energy Mezzanine Opportunities Fund II L.P. will fund up to $400 million for the development program over four years.

Darren Barbee can be reached at dbarbee@hartenergy.com.