Drilling tubular weight compensating system

Abstract

A positioning and compensation system for a tubular element to be connected to a drill string includes a gripping arm assembly with a gripping device which holds the tubular element in a position for connection to the drill string, and a load supporting and compensating arrangement which supports at least a portion of a load of the tubular element. The load supporting and compensating arrangement includes a cylinder unit having a piston, a winch, a sheave which is connected to the gripping arm assembly, and a wire. The wire is arranged to run around the sheave with a first end being connected to the piston and a second end being connected to the winch. The winch and the cylinder unit are each arranged in a respective elevated position compared to a position of the sheave. The cylinder unit maintains a minimum tension in the wire.

What is claimed is: 
     
       1. A positioning and compensation system for a tubular element to be connected to a drill string, the positioning and compensation system comprising:
 a gripping arm assembly comprising a gripping device which is configured to hold the tubular element in a position for connection to the drill string; and 
 a load supporting and compensating arrangement configured to support at least a portion of a load of the tubular element, the load supporting and compensating arrangement comprising:
 at least one cylinder unit comprising a piston, 
 at least one winch, 
 at least one sheave which is connected to the gripping arm assembly, and 
 at least one wire comprising a first end and a second end, the at least one wire being configured so that the first end is connected to the piston, the at least one wire runs around the at least one sheave, and the second end is connected to the at least one winch, 
 wherein, 
 the at least one winch and the at least one cylinder unit are each arranged in a respective elevated position compared to a position of the at least one sheave, and 
 the at least one cylinder unit is configured to maintain a minimum tension in the at least one wire. 
 
 
     
     
       2. The positioning and compensation system as recited in  claim 1 , wherein the load supporting and compensating arrangement is further configured to activate the at least one cylinder unit to maintain the minimum tension in the at least one wire when a measured tension of the at least one wire deviates from a pre-set tension. 
     
     
       3. The positioning and compensation system as recited in  claim 1 , wherein the piston of the at least one cylinder unit is configured so that a movement of the piston activates the at least one cylinder unit. 
     
     
       4. The positioning and compensation system as recited in  claim 3 , wherein the movement of the piston is controlled via a regulation of a fluid pressure in the at least one cylinder unit. 
     
     
       5. The positioning and compensation system as recited in  claim 1 , wherein,
 the tubular element is provided as a pipe element in a position where a contact is established between the pipe element and the drill string and, 
 a tension of the at least one wire is below a pre-set tension, 
 the piston is arranged to move into a position away from the at least one sheave so as to maintain the minimum tension in the at least one wire. 
 
     
     
       6. The positioning and compensation system as recited in  claim 1 , wherein,
 the tubular element is provided as a pipe element, and 
 the at least one wire is tensioned by the at least one winch in preparation for the at least cylinder unit carrying out a compensation stroke when connecting the pipe element to the drill string. 
 
     
     
       7. The positioning and compensation system as recited in  claim 6 , wherein the piston is configured to move into a position which is closer to the at least one sheave to carry out the compensation stroke when connecting the pipe element to the drill string. 
     
     
       8. The positioning and compensation system as recited in  claim 1 , further comprising:
 a vertical extending structure comprising an end portion, 
 wherein, 
 the at least one winch and the at least one cylinder unit are each arranged at the end portion of the vertical extending structure, and 
 the at least one sheave is arranged below the at least one winch and the at least one compensating cylinder unit. 
 
     
     
       9. A method for supporting at least a portion of a load of a tubular element to be connected to a drill string, wherein,
 a gripping arm assembly comprising a gripping device which is configured to hold the tubular element in a position for connection to the drill string, and 
 a load supporting and compensating arrangement configured to support at least a portion of a load of the tubular element, the load supporting and compensating arrangement comprising:
 at least one cylinder unit comprising a piston, 
 at least one winch, 
 at least one sheave which is connected to the gripping arm assembly, and 
 at least one wire comprising a first end and a second end, the at least one wire being configured so that the first end is connected to the piston, the at least one wire runs around the at least one sheave, and the second end is connected to the at least one winch, 
 wherein, 
 the at least one winch and the at least one cylinder unit are each arranged in a respective elevated position compared to a position of the at least one sheave, and 
 the at least one cylinder unit is configured to maintain a minimum tension in the at least one wire, 
 
 are each provided, and 
 the method comprises:
 measuring a tension of the at least one wire; 
 comparing the measured tension of the at least one wire to a preset tension value, and, if the measured tension of the at least one wire deviates from the preset tension value, 
 activating the at least one cylinder unit so as to maintain the minimum tension in the at least one wire. 
 
 
     
     
       10. The method as recited in  claim 9 , wherein the activating of the at least one cylinder unit so as to maintain the minimum tension in the at least one wire comprises moving the piston away from the at least one sheave. 
     
     
       11. The method as recited in  claim 9 , further comprising:
 positioning the tubular element to contact the drill string so as to cause a tension of the at least one wire to drop below the preset tension value, and, as a response thereto, 
 moving the piston away from the at least one sheave so as to reestablish/maintain the minimum tension in the at least one wire. 
 
     
     
       12. The method as recited in  claim 9 , further comprising:
 tensioning the at least one wire with the at least one winch so as to prepare the at least one cylinder unit to carry out a compensation stroke. 
 
     
     
       13. The method as recited in  claim 12 , further comprising:
 connecting the tubular element to the drill string; and 
 carrying out the compensation stroke by moving the piston towards the at least one sheave. 
 
     
     
       14. The method as recited in  claim 13 , wherein the at least one winch is at rest during the connecting of the tubular element to the drill string.