A method for measuring three-dimensional displacement of a mass comprises the steps of providing a measuring object placed on the end surface of the mass, for reflecting at least a fraction of three-dimensional displacement of the mass, arranging a displacement measuring equipment for free displacement relative to the mass and in opposition to the measuring object, and measuring three-dimensional relative displacement of the mass by detecting relative displacement of sad displacement indicative means relative to the displacement measuring equipment by the latter. The method is implemented by a three-dimensional displacement measuring system comprises a measuring object placed on the end surface of the mass, for reflecting at least a fraction of three-dimensional displacement of the mass, a displacement measuring equipment arranged for free displacement relative to the mass and in opposition to the measuring object, for measuring three-dimensional relative displacement of the mass by detecting relative displacement of sad displacement indicative means relative to the displacement measuring equipment by the latter. The method and system is suitable for measuring displacement of a rock across a crack.

A method for measuring three-dimensional displacement of a mass comprises the steps of providing a measuring object placed on the end surface of the mass, for reflecting at least a fraction of three-dimensional displacement of the mass, arranging a displacement measuring equipment for free displacement relative to the mass and in opposition to the measuring object, and measuring three-dimensional relative displacement of the mass by detecting relative displacement of sad displacement indicative means relative to the displacement measuring equipment by the latter. The method is implemented by a three-dimensional displacement measuring system comprises a measuring object placed on the end surface of the mass, for reflecting at least a fraction of three-dimensional displacement of the mass, a displacement measuring equipment arranged for free displacement relative to the mass and in opposition to the measuring object, for measuring three-dimensional relative displacement of the mass by detecting relative displacement of sad displacement indicative means relative to the displacement measuring equipment by the latter. The method and system is suitable for measuring displacement of a rock across a crack.

The invention relates to the determination of the torque T_s acting at the surface in a drillstring while drilling a borehole, the drillstring being rotated by rotating driving elements which include an electrical motor with an output shaft. The method comprises the steps of: measuring the angular acceleration γ of said shaft; measuring the torque T_m of said motor; determining the gear ratio G; determining the moment of inertia Mt of said rotating driving elements; and determining the torque T_s from the values of γ, T_m, G and Mt.

In the representative embodiments of the present invention described herein, new and improved methods and apparatus are disclosed for measuring various forces acting on an intermediate body between the lower end of a drill string (11) and the earth-boring apparatus (14) coupled thereto whereby the magnitudes and angular directions of bending moments and side forces acting on the earth-boring apparatus (14) can be readily determined so that predictions can be made of the future course of excavation of the apparatus.

Method for displacing a logging tool through a on-gravity descent portion of a well such as a highly deviated portion (11), comprising the steps of providing a logging tool (16) at the lower end of a drill pipe (15) as an exposed extension to said drill pipe, displacing the tool thus exposed through said portion of the well by connecting additional sections of drill pipe and lowering the drill pipe, and, during this displacing step, continuously generating and sending uphole a signal indicative of the compressive load undergone by the tool.

In a method of determining the length change of a string oftubing (12) in a vertical or deviated well caused by fluid flow through the tubing during production or stimulation of the well, the pressure of the fluid is measured where the fluid enters the tubing and, for successive sections of the tubing, the actual force applied to the tubing is determined from the fluid pressure acting upon the cross-sectional area of the tubing. The inclination and weight of each section of the tubing is measured and from the measured inclination the weight of each section is resolved into the axial component applied to the next successive segment. For each of the successive sections, the buckling force is determined from the actual force and the axial component of the weight and then the buckling force is compared to a threshold to determine if there is buckling of the tubing. The length change of the tubing (12) between the initial condition and the condition of fluid flow in the tubing caused by the pressure and temperature of the fluid and caused by any buckling is then determined and an output is produced indicating the change in length of the tubing.