Cheap oil prices aren't the only risk to Warren Buffett and Berkshire Hathaway's $825 million acquisition of Weatherford's oilfield chemicals and drilling fluids businesses. The global water shortage also poses a risk to the deal. Fracking a typical well uses two to eight million gallons of water, according to the New York State Department of Environmental Conservation. That's leading fracking companies to look for new, water-free methods of extracting oil and gas from rocks. If fracking evolves into a technique that doesn't use water, Weatherford may find itself struggling to stay relevant. Analysts at Oppenheimer don't seem concerned about Weatherford yet. Since the deal was announced, Oppenheimer initiated coverage of the company with an outperform rating and $19 price target.