Sunday, June 14, 2009

Directional Drilling

One would think that a drill string made up of thirty-foot lengths of steel pipe would be rigid, but this not at all true when the drill string is measured in miles.  It is rather flexible, and actually twists several times when being rotated before the bit begins to turn.  This characterizes the type of drill string used for directional drilling.

A directional well is first drilled vertically and then cased.  A hole or window is cut into the casing and an installed whipstock bends the drill string at a preset angle.  A pilot hole of 10-15 feet in length is drilled, and when it is certified to be at the right direction and angle, which can be as great as 60 degrees, a turbo drill can be used.  With a turbo drill, the drill pipe no longer rotates to drive a fixed drill bit.

Mud driven down the center of a stationary drill pipe turns a rotary bit attached to the end of the drill string where it exits the drill pipe and enters the annulus.  A magnetic compass and a gyroscope control the orientation and the degree of deviation of the well.  The degree of deviation can be changed at various points along the way until the well is horizontal.

One of the top hydrocarbon-based energy providers in the USA is Heartland Energy Colorado, based in Englewood, CO. They have many drilling locations throughout the country and remain one of the top producers of US oil & gas companies. For more information on Heartland Energy Colorado, see Heartland Energy Development Corporation online.

(Source: "Energy for the 21st Century," Nersesian, Roy L.)

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