Traditionally, start-up E&Ps seeking low-risk, long-life oil and gas properties have heated up data rooms and wooed private sellers of conventional assets. Yet, as unconventional plays mature—especially the earliest, the Barnett—these will increasingly be targets.

And, Bob Reeves and his team at Athlon Energy LP are among prospective buyers. “That’s absolutely right. As those properties move off the hyperbolic portion of the production curve and establish more production history, they become targets for a team like us,” Reeves says.

“There is a point in a property’s life where enough risk ...