The Niobrara enters as the newest star in the rush to horizontal development of shales in North America with activity centered on the Denver Basin in northeastern Colorado and spreading throughout Colorado and Wyoming.

The shale covers much of the Rocky Mountain province, but operators have directed little attention to its potential for production with horizontal wells and modern fracture treatments until lately.

Still, it is a proven producer when the economics are right. In the 1980s, operators had trouble finding positive economics from the Niobrara Chalk in the Denver ...