The Davis family has owned ranchland on the high-desert prairie of El Paso County in Colorado for the past century. Family lore recalls a prophecy of wealth from the Depression years. A geologist came through the desolate region, nestled on the Front Range of the Rocky Mountains, and told the family there might be oil (CL-FT102.74-0.48-0.47%) under their land. In the seven decades since the 1930s, there hasn’t been a single successful oil well on the Davis land – or anywhere else in all of El Paso County, a mostly rural region located south of Denver.

Now, however, subsurface fracturing – or fracking – technology so widely used in natural gas drilling is beginning to unlock oil reserves long considered impossible to tap successfully, like the suddenly prolific Bakken play in North Dakota