Great read on the Permian field in the US....https://oilprice.com/Energy/Crude-Oil/Fifty-Shades-Of-Shale-Oil.html
Interesting take on the Permian basin and expectation of a decline starting in 2020....the last few paragraphs are quite telling...
Considering that the majority of U.S. tight oil production growth is generated by a single field, the Permian, changes in the growth outlook of this basin have major implications as to the evolution of global oil prices over the short, medium and long term. Its important to keep in mind that the Permian oil field, despite its large scope, is bound to flatten, peak and decline at some point. While forecasters differ as to the exact year when the Permian oil production will flatten, the majority agree that a slowdown in Permian oil production growth will take place in the early 2020s.