The West Texas drilling frenzy that sparked one of the the biggest oil boom in U.S. history could fizzle out in just four years if crude prices stay too low to spur innovations needed to overcome the region's geological constraints. For months, oil has gushed from newly drilled wells and pumpjacks e-rected across the plains of the Permian Basin, a prolific shale play that has drawn billions of dollars of investment from major energy companies and speculators, and become the epicenter of the oil industry's recovery.