(Bloomberg Businessweek) -- Twenty years ago, before the U.S. oil industry became a global energy power that strikes fear into Saudi Arabia, brothers Dan and Farris Wilks started Frac Tech Services LLC in tiny Cisco, Texas. The company provided equipment for hydraulic fracturing, aka fracking, the breaking up of tight sedimentary rock by blasting water, sand, and assorted chemicals through horizontal bores at fantastically high press...