(CNBC) A further slump in oil prices may dampen shale drilling's profitable run, according to a report from Goldman Sachs.
In the past four weeks, global oil prices plunged eight percent. And a barrel in the U.S. is below $90, the first time in two years. On Thursday, shares of companies centered in North Dakota's Bakken Shale dropped more than 5 percent.
If prices drop any further, the Wall Street Journal reports, drilling activity would slow down drastically.
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