Tension
http://www.drillingformulas.com/wp-content/uploads/2013/09/derrick-Load-Calculation-1.jpgWith drill pipe averaging about 12 pounds per foot and a hypothetical well depth of 20,000 feet, there is 120 tons of metal pipe downhole. While the weight of all this pipe is partially offset by displacing the drilling fluid that fills the hole, that's an amazing amount of weight! Weight is also known as the force caused by gravity, and it can be calculated by using the following formula:
William Czyzewski
This formula states
that the gravity's force on the object is equal to the
object's mass in kilograms multiplied by the
acceleration provided by gravity. With 120 tons of
metal pipe, we see a force of gravity of 1,070,000
newtons. This is the force pulling down on the
pipe. To offset this force, we need to balance it
out with another force that pulls up on the pipe.
Without a force that can offset or exceed gravity's, we
would never be able to lift our drill pipe out of the
hole or drill properly. The force we need is
called tension. It is seen in the thick steel
cables in the pulley system in the drill rig's
derrick. In a perfectly balanced situation, the
force of tension in the cables must also equal 1,070,000
newtons! In the end, we generally see that:
William Czyzewski
William Czyzewski