The promise of the Permian is shrinking. : Producers in the nation’s oil-rich shale basins are dialing back growth plans in the face of a growing panoply of problems that’s killing returns, and keeping skeptical investors away. The constraints are manifold: pipeline limits, reduced flow from wells drilled too close together, low natural gas prices and high land costs. But the most consequential is that shale-well production falls off at such a high rate -- as much as 70% in the first year -- that you need to keep spending cash on new wells just to maintain output.