Weren't a lot of wells simply capped back in the 1980s?
Not really. They were simply shutin when oil prices plummeted below $10/B. Economics could not support producing marginal wells that could not recoup their operating expenses. Majors at the time were beginning to question the wisdom of operating in such a mature area and began planning departing a lot of their acreage which accelerated during the 90s.
This caused the rise of a number of independents who seized the Permain acreage and exploited it as the 'Big Boys' left for other pastures, mostly in Offshore basins around the world.
The Permian became staples for companies like Occidental, Anadarko and Apache, among others.
Now the majors are returning to concentrate upon the basin they had left years ago.