Directional drilling provided a step-change in the oil and gas industry, allowing those companies to adopt what is known as “horizontal drilling,” as opposed to vertical drilling. Since the advent of the petroleum industry, wells were drilled straight down, but that meant that the well itself could only reach a small portion of the typically flat, pancake-like reservoir deep underground. Directional drilling turns the drillbit in a targeted manner so that a well that starts vertically will make a 90 degree turn and then run horizontally, sometimes for several kilometres, greatly increasing contact with the producing formation. The horizontal drilling revolution, which took hold in the 1990s, has become so commonplace that nearly all wells drilled today are directionally drilled horizontal wells.