Directional casing and liner drilling with mud motor

Abstract

A directional casing drilling system includes a casing string, a mud motor operatively coupled to the casing string, a rotary steerable system operatively coupled to the mud motor, and a drill bit operatively coupled to the rotary steerable system.

1 . A directional casing drilling system, comprising: 
 a casing string;    a mud motor operatively coupled to the casing string;    a rotary steerable system operatively coupled to the mud motor; and    a drill bit operatively coupled to the rotary steerable system.    
   
   
       2 . The directional casing drilling system of  claim 1 , further comprising an underreamer disposed below the casing string and above the drill bit, and operatively coupled to the casing string.  
   
   
       3 . The directional casing drilling system of  claim 1 , further comprising a casing shoe cutter disposed at a bottom end of the casing string.  
   
   
       4 . The directional casing drilling system of  claim 1 , wherein the rotary steerable system comprises a push-the-bit system.  
   
   
       5 . The directional casing drilling system of  claim 1 , wherein the rotary steerable system comprises a point-the-bit system.  
   
   
       6 . The directional casing drilling system of  claim 1 , further comprising a measurement while drilling collar disposed above the mud motor and operatively coupled to the casing string.  
   
   
       7 . The directional casing drilling system of  claim 1 , further comprising an articulating casing latch.  
   
   
       8 . A directional casing drilling system comprising: 
 a casing string having an integral bend proximate a lower end of the casing string;    a mud motor operatively coupled to the casing string; and    a drill bit operatively coupled to the mud motor.    
   
   
       9 . The directional casing drilling system of  claim 8 , further comprising an underreamer positioned between the drill bit and the casing string and operatively coupled to the casing string.  
   
   
       10 . The directional casing drilling system of  claim 8 , wherein the mud motor is disposed inside the lower end of the casing string.  
   
   
       11 . The directional casing drilling system of  claim 8 , further comprising a measurement-while-drilling device.  
   
   
       12 . The directional drilling system of  claim 11 , wherein the measurement-while-drilling device is positioned above the mud motor and coupled to the casing string.  
   
   
       13 . The directional drilling system of  claim 8 , further comprising an offset centralizer disposed inside the casing string at the lower end of the casing string.  
   
   
       14 . A method of directional drilling, comprising: 
 rotating a casing string at a first speed that is slower than an optimum drilling speed;    operating a mud motor to rotate a drill bit at a second speed; and    changing the direction of the drill bit by operating a rotary steerable system.    
   
   
       15 . The method of  claim 14 , further comprising enlarging a pilot hole drilled by the drill bit using an underreamer coupled to the casing string.  
   
   
       16 . The method of  claim 14 , wherein a bottom end of the casing string comprises a casing shoe cutter and further comprising enlarging a pilot hole drilled by the drill bit using the casing shoe cutter.  
   
   
       17 . The method of  claim 14 , further comprising: 
 measuring a drill bit azimuth and a drill bit inclination; and    adjusting a drilling direction based on at least one of the drill bit azimuth and the drill bit inclination.    
   
   
       18 . A method of directional casing drilling, comprising: 
 positioning a casing string so that a bend in a lower section of the casing string points in a desired azimuthal direction; and    engaging a mud motor to rotate a drill bit.    
   
   
       19 . The method of  claim 18 , further comprising: 
 measuring a drill bit azimuth and a drill bit inclination; and    repositioning the casing string based on at least one of the drill bit azimuth and the drill bit inclination.    
   
   
       20 . The method of  claim 18 , further comprising: 
 measuring a drill bit azimuth and a drill bit inclination;    determining when the drill bit is pointed in a desired direction from at least one of the drill bit azimuth and the drill bit inclination; and    drilling a straight path by rotating the casing string.