Question

During drilling of a deep oil well, the drill pipe got rigidly stuck. It was necessary to determine the depth at which the jamming occurred. The engineer ordered the pipe subjected to a large upwards tensile force, i.e., she pulled on it. As a result, the top of the pipe came up due to elastic stretch by 550 mm. At the same time, measurements showed that the pipe elongated by 0.35 mm in a 200 mm gauge length. Determine the depth at which the pipe was stuck. Assume the cross-section of the pipe is constant with depth

Answer 1

Here is my solution for the above problem.
Rate of strain = 0.35/200 = 1.75x10e-3

Since no external force is applied rate of strain will be same for entire length.

Let's assume depth of clay as L

then,
extension/Total length of pipe = rate of strain

500 mm / L = 1.75x10e-3

Hence L = 285.7 m.

Depth of clay = Length of pipe + height of derrick.