**2. History of hydrofracking technique**

What is called hydrofracking in the popular vernacular is actually two technologies. It is a combination of horizontal drilling and high-volume hydraulic fracturing. The first is horizontal drilling, in which the well drills horizontally through the oil- or gas-bearing rock layer. The second is high-volume hydraulic fracturing in which highly pressurized water is used to fracture the oil- or gas-bearing rock formation and sand transported with the high-pressure water props the fractures open.

Neither is an entirely new technology. Directional drilling was used to drill for offshore oil in southern California in the 1920s. Drillers would drill vertically from an onshore location and then cause the drill bit to angle west to tap formations below the ocean [1]. From that time the technology has steadily advanced until the present day where drillers have excellent control of the depth and angle of the turn from vertical, the ultimate depth of the horizontal portion, and the 3D orientation of the drilling.
