Directional drilling

Measuring the azimuth (direction with respect to the geographic grid in which the wellbore was running from the vertical), however, was more difficult.

Counter-experience had also given early directional drillers ("DD's") principles of BHA design and drilling practice that would help bring a crooked hole nearer the vertical.

[citation needed] In 1934, H. John Eastman and 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.

This capacity to quickly drill multiple relief wells and relieve the enormous gas pressure was critical to extinguishing the Conroe fire.

[2] In a May, 1934, Popular Science Monthly article, it was stated that "Only a handful of men in the world have the strange power to make a bit, rotating a mile below ground at the end of a steel drill pipe, snake its way in a curve or around a dog-leg angle, to reach a desired objective."

[citation needed] Combined, these survey tools and BHA designs made directional drilling possible, but it was perceived as arcane.

RSS technology has made access and directional control possible in previously inaccessible or uncontrollable formations.

Such pictures, or surveys, are plotted and maintained as an engineering and legal record describing the path of the well bore.

The current record holders manage wells over 10 km (6.2 mi) away from the surface location at a true vertical depth (TVD) of only 1,600–2,600 m (5,200–8,500 ft).

What remains is a difference in operating costs: for wells with an inclination of less than 40 degrees, tools to carry out adjustments or repair work can be lowered by gravity on cable into the hole.

[5] The United Nations redrew the border after the 1991 Gulf war, which ended the seven-month Iraqi occupation of Kuwait.

[6] In the mid-twentieth century, a slant-drilling scandal occurred in the huge East Texas Oil Field.

[9] Specialized tools determine the wellbore's deviation from vertical (inclination) and its directional orientation (azimuth).

A horizontal directional drill in operation
A structure map generated by contour map software for an 8,500-foot-deep (2,600 m) gas and oil reservoir in the Erath field, Vermilion Parish , Erath, Louisiana . The left-to-right gap, near the top of the contour map indicates a fault line . This fault line is between the blue/green contour lines and the purple/red/yellow contour lines. The thin red circular contour line in the middle of the map indicates the top of the oil reservoir. Because gas floats above oil, the thin red contour line marks the gas/oil contact zone. Directional drilling would be used to target the gas and oil reservoir .
Government Accountability Office depiction of horizontal drilling being used to cross tracts of land with differing owners