Multi-start thread connection for downhole tools

Abstract

An apparatus for transferring rotary power to a consumer in a wellbore includes a rotary power source positioned along a conveyance device and a drive train connected to the rotary power source. The drive train transfers torque from the rotary power source to a consumer. The drive train includes at least two torque transmitting members connected by a multi-start thread connection.

What is claim is: 
     
         1 . An apparatus for transferring rotary power to a consumer in a wellbore, comprising:
 a conveyance device configured to be disposed in the wellbore;   a rotary power source positioned along the conveyance device, the rotary power source generating a torque; and   a drive train connected to the rotary power source, the drive train transferring the torque from the rotary power source to a consumer, wherein the drive train includes at least two torque transmitting members connected by a multi-start thread connection.   
     
     
         2 . The apparatus of  claim 1 , wherein the multi-start thread connection is formed at a pin and box connection between the at least two torque transmitting members. 
     
     
         3 . The apparatus of  claim 1 , wherein a number of starts of the multi-start thread connection is selected to increase torque capacity of a connection between the at least two torque transmitting members relative to a single start thread connection. 
     
     
         4 . The apparatus of  claim 1 , wherein the rotary power source is a drilling motor. 
     
     
         5 . The apparatus of  claim 1 , wherein the consumer is a drill bit. 
     
     
         6 . The apparatus of  claim 1 , wherein at least one of the two torque transmitting members is one of: (i) a rotor, (ii) flex shaft, and (iii) a drive shaft. 
     
     
         7 . The apparatus of  claim 1 , wherein the conveyance device is a drill string. 
     
     
         8 . The apparatus of  claim 1 , wherein the multi-start screw has at least two intertwined helically wound threads. 
     
     
         9 . A method for transferring rotary power to a consumer in a wellbore, comprising:
 disposing a conveyance device in the wellbore, the conveyance having a rotary power source generating a torque; and   transferring torque from the rotary power source using a drive train, wherein the drive train includes at least two torque transmitting members connected by a multi-start thread connection.   
     
     
         10 . The method of  claim 9 , wherein the multi-start thread connection is formed at a pin and box connection between the at least two torque transmitting members. 
     
     
         11 . The method of  claim 9 , wherein a number of starts of the multi-start thread connection increases torque capacity of a connection between the at least two torque transmitting members relative to a single start thread connection. 
     
     
         12 . The method of  claim 9 , wherein the rotary power source is a drilling motor, the consumer is a drill bit, and wherein at least one of the two torque transmitting members is one of: (i) a rotor, (ii) flex shaft, and (iii) a drive shaft. 
     
     
         13 . The method of  claim 9 , wherein the multi-start screw has at least two intertwined threads. 
     
     
         14 . A system for transferring rotary power to a consumer in a wellbore, comprising:
 a drill string conveyed into the wellbore; and   a bottomhole assembly connected to the drill string, the bottomhole assembly including:   
       a drilling motor energized by a drilling fluid circulated in the wellbore, and 
       a drive train connected to the rotary power source, the drive train transferring the torque from the rotary power source to a consumer, wherein the drive train includes a multi-start thread formed at a pin and box connection between at least two torque transmitting members. 
     
     
         15 . The system of  claim 14 , the at least one of the two torque transmitting members include a rotor, a flex shaft, and a drive shaft interconnected to one another. 
     
     
         16 . The system of  claim 14 , wherein the number of starts of the multi-start thread is selected to reduce the transmitted torque to a value lower than the make-up torque. 
     
     
         17 . The system of  claim 14 , wherein the multi-start screw has at least two intertwined threads.