Continuous drilling system

Abstract

A drill string management apparatus is disclosed. The apparatus may comprise a reel that stores a length of drill string and supplies the drill string to a drilling system. The drill string may be wrapped around a circumference of a reel in a coil. The radius of the coil may be large enough that the drill string is not deformed inelastically by wrapping it around the reel. The apparatus may be designed to allow the drill string to rotate about its longitudinal axis, even as the drill string is wrapped in a coil around the reel.

What is claimed is: 
     
         1 . A method for deploying a drill string into a borehole, the method comprising:
 providing a drill string arranged to lie along a curving path outside of and adjacent to a borehole, extending a tail end portion of the drill string into the borehole, each point of the curving path having a radius of curvature greater than a threshold radius such that the drill string is elastically bent to follow the curving path; and   rotating the drill string about a longitudinal axis of the drill string while the drill string lies along the curving path.   
     
     
         2 . A method according to  claim 1 , comprising rotating the drill string about the longitudinal axis while tripping the drill string into or out of the borehole. 
     
     
         3 . A method according to  claim 1  comprising providing a drill bit coupled to the tail end of the drill string, and rotating the drill string about the longitudinal axis while allowing the drill bit to extend into the borehole. 
     
     
         4 . A method according to  claim 3  comprising flowing a drilling fluid through the drill string. 
     
     
         5 . A method according to  claim 4  wherein flowing the drilling fluid through the drill string is performed while rotating the drill string about the longitudinal axis. 
     
     
         6 . A method according to  claim 4  wherein flowing the drilling fluid through the drill string is performed while tripping the drill string into or out of the borehole. 
     
     
         7 . A method according to  claim 4  comprising monitoring a pressure of the drilling fluid in real time at a location proximate the tail end of the drill string and controlling a flow of the drilling fluid based at least in part on the monitored pressure. 
     
     
         8 . A method according to  claim 1  wherein arranging the drill string to follow the curved path comprises wrapping the drill string around a first reel to form a coil around the reel. 
     
     
         9 . A method according to  claim 8  wherein the first reel has a diameter of at least 30 meters. 
     
     
         10 . A method according to  claim 8  wherein the first reel has a diameter of at least 50 meters. 
     
     
         11 . A method according to  claim 8  wherein the first reel has a diameter in the range of about 30 to 125 meters. 
     
     
         12 . A method according to  claim 8  wherein wrapping the drill string around the first reel comprises making at least 4 wraps of the drill string around the first reel. 
     
     
         13 . A method according to  claim 8  comprising supporting a weight of a portion of the drill string that is in the borehole by an elevator of a drilling system adjacent to the first reel. 
     
     
         14 . A method according to  claim 13  wherein rotating the drill string about the longitudinal axis comprises applying a first torque to a portion of the drill string passing through the drilling system. 
     
     
         15 . A method according to  claim 14  comprising, while rotating the drill string about the longitudinal axis applying a second torque to an uphole end of the drill string on the first reel. 
     
     
         16 . A method according to  claim 13  wherein rotating the drill string about the longitudinal axis comprises applying a torque to an uphole end of the drill string. 
     
     
         17 . A method according to  claim 8  further comprising removing the tail end portion of the drill string from the borehole and rotating the first reel to wrap the tail end portion of the drill string onto the first reel and operating a tensioner on the first reel to maintain the drill string under tension. 
     
     
         18 . A method according to  claim 1  wherein the drill string has a diameter of about 4 inches (about 10 cm) or more. 
     
     
         19 . A method according to  claim 1  wherein the drill string comprises 100 or more tubulars coupled end to end. 
     
     
         20 . A method according to  claim 19  wherein the one or more tubulars are coupled end to end by shrink fit connections. 
     
     
         21 . A method according to  claim 19  wherein the one or more tubulars are coupled end to end by threaded joints. 
     
     
         22 . A method according to  claim 19  wherein the one or more tubulars are coupled end to end by welding. 
     
     
         23 . A method according to  claim 4  comprising feeding an umbilical cable into an interior of the drill string and carrying the cable into the drill string by flowing the drilling fluid. 
     
     
         24 . A method according to  claim 1  comprising aligning a support deck of the first reel with a well center of the borehole. 
     
     
         25 . A method according to  claim 1  comprising wrapping a second drill string around a second reel to form a second coil around the second reel. 
     
     
         26 . A method according to  claim 25  comprising moving the first reel away from a well center of the borehole and aligning a support deck of the second reel with the well center of the borehole. 
     
     
         27 . A method according to  claim 26  comprising extending a tail portion of the second drill string into the borehole and rotating the second drill string about a longitudinal axis of the second drill string while the second drill string forms the second coil around the second reel. 
     
     
         28 . A method according to  claim 25  comprising wrapping a casing around one or both of the first and second reels and installing the casing in the borehole. 
     
     
         29 . A method according to  claim 1  comprising:
 stopping rotation of the first reel; 
 operating a tensioner on the first reel to maintain the drill string under tension; 
 uncoupling first and second tubulars of the drill string; 
 installing a stabilizer on the first tubular; 
 re-coupling the first and second tubulars; and 
 disengaging the tensioner and restarting rotation of the first reel.