Apparatus for measuring weight, torque and side force on a drill bit

摘要

Apparatus is presented for measuring weight, torque and side force (bending) on a drill bit for oil and gas well drilling. Strain gages are located in radial holes in the wall of a drill collar sub for measuring each of the three parameters of weight, torque and bending. The holes are sealed by inner and outer plugs and a ring and bolt structure retains the plugs in place. For torque and bending measurements, the strain gages are arranged with symmetry of position beteween diametrically opposed holes. The strain gages are positioned in a novel array which departs from symmetry of position to minimized errors in the weight measurement caused by pressure changes in the drilling fluid.