Load-measuring apparatus for use in downhole drilling tool suspended in the wellbore, comprises drill collar for magnifying deformation resulting from the received forces, and sensor for measuring deformation of the drill collar

摘要

A load-measuring apparatus comprises a drill collar for magnifying deformation resulting from the received forces, and a sensor mounted in the drill collar. The sensor measures the deformation of the drill collar, thus the forces on the drilling tool are determined. Independent claims are also included for: (A) a method of determining a load acting on a downhole tool, comprising determining an electrical property of a sensor disposed in the downhole tool when the load is applied to the downhole tool, and determining a magnitude of the load based on a difference between the electrical property of the sensor when the drill collar is in a loaded condition and the electrical property of the sensor when the drill collar is in a relaxed condition, where the electrical property of the sensor is changed because the load causes a change in one selected from a relative position of a first and a second element of the sensor and an area between the first and second element; and (B) a downhole sensor for measuring a load on a downhole drilling tool suspended in a wellbore via a drill string, comprising first and second sensor elements, which are coupled to the downhole tool such that one selected from a relative position of the first and second element and an area between the two elements is changed when the drilling tool is subjected to the load.