The Barnett shale in Texas is primarily a gas play and is as relatively large in that respect as the Bakken is in oil production. Additionally, since this is relatively new technology oil companies are looking at known formations they have passed on previously because they didn’t have the technology to exploit it. I believe the article states the Bakken was well known for decades but couldn’t be exploited. That’s true in many places.
The effort involved makes Barnett Shale wells very expensive wells.
The issue I see with the Bakken is that unless you are in sweet spot [lots of communicated fracturing or maybe clean sandy streaks], the oil just isn’t going to flow to the well bore anywhere near as readily as would natural gas.