Apparatus for determining the dynamic forces on a drill string during drilling operations

Abstract

The Apparatus acting as a counterforce presented for measuring, indicating and recording the weight of the drill string, the torque applied to the drill string and the bending force at the top drive during drilling operations where a plurality of strain gauges for measuring the force of tension, torque and bending with indexing are suitably mounted on the counterforce to optimize the accuracy and limit the cross sensitivity between the forces. The counterforce is installed at the top of the drill string contained within the top drive assembly. Polynomial regression analysis provides the coefficients for digital signal conversion to engineering units. The strain gauges are connected to a circuit board that facilitates external communication for calibration purposes and the sending and receiving of data. The counterforce requires no physical adjustment after manufacture. The circuits contained within the counterforce are battery driven. The apparatus is certified for use in hazardous atmospheres.

1 . The present invention relates to the measurement of the dynamic forces on a drill string during the drilling of a wellbore by application of an apparatus that is mounted at the top of the drill string with means for computing weight, torque, bending, indexing and velocity of rotation of a rotating drill string, comprising a counterforce, transducer means mounted directly on the surface of the said counterforce, circuit means associated with said transducer means, the circuit means associated with the transducers means generates digital signals representative of the axial, torsional and bending forces applied to the said counterforce, the velocity of rotation with an index marker, the said circuit means to be responsive to external communication, means for storing digital correction representations, circuit means responsive to external commands for control, circuit means for storing unique addresses, circuit means for transmitting said digital representations, the transducer and circuit means sealed in an enclosure with means for external communication with said circuit means. 
   
   
       2 . An apparatus as claimed in  claim 1  which forms part of the bottom shaft assembly of a top drive, the said counterforce manufactured from a high strength material with suitable end connections compliant with drilling codes of practice and a machined area to house the transducer and circuit means with associated batteries, the whole protected by a machined cover. 
   
   
       3 . An apparatus as claimed in  claim 1  where the said transducer means consist of a plurality of strain gauges arranged such to minimise transmigration of signals between said transducers. 
   
   
       4 . An apparatus as claimed in  claim 1  where the said circuit means includes a telemetry device as the communicating means. 
   
   
       5 . An apparatus as claimed in  claim 1  where mud control valves both manual and remotely operated be included in the body of the apparatus. 
   
   
       6 . An apparatus in accordance with the above claims including computing means and transmitting means; the computing means computing weight of a drill string, torque of a drill string and bending force; the transmitting means transmitting the computed data of weight, torque and bending via radio telemetry and a receptor with radio telemetry means for receiving said data processor means for display of said data computer means for receiving and storing the said data from the electronic load cell and torque transducer. 
   
   
       7 . A transducer in accordance with the above claims measuring tensile and compressive forces, wherein an output signal representative to drill string weight be available for control means. 
   
   
       8 . A transducer in accordance with the above claims measuring torsional stress in shear wherein an output signal representative to the torque applied to the drill string be available for control means. 
   
   
       9 . A transducer in accordance with the above claims measuring bending wherein an output signal representative to the radial bending force on the drill string torque be available for control means. 
   
   
       10 . An index pulse radially linked to the position of the tension, torque and bending signals 
   
   
       11 . Transducers in accordance with  claims 7 ,  8 ,  9  and  10 , wherein an output signal be available in an intranet protocol for remote monitoring and or control. 
   
   
       12 . An enclosure, housing the transducer and circuit means with means for external communication with said circuit means, be certified for use in hazardous atmospheres.