Coterra Energy is now experimenting on when to land wells in the Harkey Mills sandstone where it has the extra formation in the Delaware Basin.

The experiment will be part of a 54-well, 12-section drilling spacing unit (DSU).

The Harkey sits between the second and third Bone Spring benches, which are above the Wolfcamp.

The project, which Coterra calls Windham Row, will consist of 51 wells landed in Upper Wolfcamp and three in Harkey. In the area, the Wolfcamp is at some 9,000 ft.

Windham Row well design
Coterra Energy plans to land 51 Wolfcamp wells and three Harkey wells initially in the Windham Row project that involves a 12-section block. (Source: Coterra Energy)

Tom Jorden, Coterra chairman, president and CEO, told investors in May that his and the team’s observation in the Delaware is generally that there isn’t an EUR boost from a DSU “whether we exploit these reservoirs one layer at a time or not.”

But it might help pare the cost of infrastructure if the company is able to add wells over time. “Doing them in stages allows us to … not have to build facilities for absolute peak production—because these wells do decline,” he said.

With tank batteries built for peak production, for example, “you find that very early in their life they’re underutilized.”

Yet, Coterra saw in an experiment through the past couple of years that with “co-developing the Harkey and the Wolfcamp at the same time—versus waiting 12 to 24 months and coming back with the Harkey—we did see what we think is an incremental boost in recovery.

“We’re not concluding that, but we prudently added in the [Windham] Row a few Harkey wells.”

Windham Row project location
Coterra Energy’s Windham Row project is in northeastern Culberson County. (Source: Coterra Energy)

Blake Sirgo, Coterra senior vice president of operations, said 34 of the Windham Row wells are already drilled and were being completed in early May. Some of the wells will begin to go into production this month.

“We’ve just seen some results lately that say the performance of the Harkey is better when we co-develop [it] with the Upper Wolfcamp versus overfill [it later] and we’re interested in learning more about that,” he told investors.

Coterra reported on the Harkey in the spring of 2023. “We love the Harkey,” Jorden told investors at the time. “In a lot of our position, it competes very nicely with Wolfcamp.”

A Coterra test in 2023 consisted of a co-development of nine Wolfcamp and four Harkey wells. Coterra reported in May that the DSU was “performing in line with expectations.”

Randy Nickerson, Caza Petroleum’s COO, told Hart Energy in 2019 that the Harkey in the northern Delaware Basin, such as in Eddy County, New Mexico, “is a little more highly oil saturated than the other [zones]. I think you’re going to see that’s going to be a new bench out there.”

The 51 Wolfcamp wells and three Harkey wells will be made first. Coterra plans to return to the project with one more Harkey well some 12 months after the 54-well project is online.

The project is Coterra’s largest to date.