METHOD AND DEVICE FOR DETERMINING THE EXISTENCE AND LOCATION OF STRESS-INDUCING FORCES ON A ROD

摘要

The present invention relates to methods for determining the existence and location of parasitic stress-inducing forces on a substantially cylindrical rod portion 1 defined along a first axis 2 and when this rod is made of a magnetostrictive material. The method according to the invention is essentially characterized in that it consists in magnetizing the wall of the rod portion in a pseudo-helix 10 centred on the first axis 2, in applying a forced stress between the two ends 3, 4 of the rod portion 1, in measuring, along the rod portion, the magnitude of the magnetic field created by the rod portion 1 after it has been subjected to the forced stress, these measurements being taken in a direction substantially parallel to the first axis 2, and from these measurements, in deducing the existence and location of the parasitic stress-inducing forces on the rod portion 1. The invention also relates to a device for implementing this method. Advantageous application to the determining of the location of a sticking point Pc of a hollow drill rod string which has become stuck in an oil well.