By now everyone knows the shale revolution was made possible by the combination of horizontal drilling and hydraulic fracturing. But although fracking has captured the popular imagination, and is often used as a synonym for the whole phenomenon, horizontal drilling was actually the more recent and important breakthrough. Mastery of horizontal drilling around 1990, originally for oil rather than gas exploration, was the decisive innovation that lit the long fuse for the shale revolution that erupted 15 years later. “Horizontal drilling is the real marvel of engineering and scientific innovation,” David Blackmon wrote in Forbes magazine last year (“Horizontal drilling: a technological marvel ignored”, January 2013). “While impressive in its own right, the main innovations in fracking have been beefing up the generating horsepower to accommodate horizontal wells rather than vertical ones, and refining of the fluids used to conserve water and […]