Updated: Jul 10, 2019
In 1934, H. John Eastman & Roman W. Hines of Long Beach, California, became pioneers in directional drilling when they and George Failing of Enid, Oklahoma, saved the Conroe, Texas, oil field. Failing had recently patented a portable drilling truck. He had started his company in 1931 when he mated a drilling rig to a truck and a power take-off assembly. The innovation allowed rapid drilling of a series of slanted wells. This capacity to quickly drill multiple relief wells and relieve the enormous gas pressure was critical to extinguishing the Conroe fire.
Three components are measured at any given point in a wellbore in order to determine its position: the depth of the point along the course of the borehole (measured depth), the inclination at the point, and the magnetic azimuth at the point. These three components combined are referred to as a "survey". A series of consecutive surveys are needed to track the progress and location of a wellbore. This survey process was invented in the 1920s by the Sherry Corporation.
The next major advance was in the 1970s, when downhole drilling motors (aka mud motors, driven by the hydraulic power of drilling mud circulated down the drill string) became common. These allowed the drill bit to continue rotating at the cutting face at the bottom of the hole, while most of the drill pipe was held stationary. A piece of bent pipe between the stationary drill pipe and the top of the motor allowed the direction of the wellbore to be changed without needing to pull all the drill pipe out and place another whipstock.
Combined, these new technologies made directional drilling possible and would be very beneficial to the oil and gas industry. Some of the benefits include:
-Increasing the exposed section length through the reservoir by drilling through the reservoir at an angle -Drilling into the reservoir where vertical access is difficult or not possible. -Drilling along the underside of a reservoir-constraining fault allows multiple productive sands to be completed at the highest stratigraphic points. -Drilling a "relief well" to relieve the pressure of a well ultimately preventing blow-outs.