Back-Reaming Rotary Steering

Abstract

A rotary steerable system (RSS) having multiple steering pads, a valve to sequentially actuate the plurality of steering pads, and a back-reaming bit formed by multiple cutting elements carried by each of the steering pads. While rotating the drill string, the RSS, and the drill bit, the valve and/or the controller are operated to sequentially actuate the steering pads to operatively urge the RSS and the drill bit away from a longitudinal axis of the wellbore, thus steering the wellbore drilling direction. Thereafter, while rotating the drill string, the RSS, and the drill bit, the valve and/or the controller are operated to simultaneously actuate each of the steering pads to operatively urge at least one of the cutting elements on each of the steering pads into contact with a sidewall of the wellbore, thus back-reaming the wellbore.

What is claimed is: 
     
         1 . A system for drilling a wellbore, comprising:
 a rotary steerable system (RSS) at least indirectly coupled between a drill string collar and a drill bit, wherein the RSS comprises:
 a housing; 
 a plurality of steering pads circumferentially spaced around the housing, wherein each of the plurality of steering pads is actuatable to radially extend away from the housing independent of the other ones of the plurality of steering pads, and wherein at least one of the plurality of steering pads comprises a back-reaming bit; 
 a valve; and 
 a controller, wherein the valve and the controller are collectively operable to:
 sequentially actuate ones of the plurality of steering pads to substantially decentralize the RSS relative to the wellbore; and 
 simultaneously actuate each of the plurality of steering pads to substantially centralize the RSS relative to the wellbore, thus urging the back-reaming bit into contact with a sidewall of the wellbore. 
 
   
     
     
         2 . The system of  claim 1  wherein each of the plurality of steering pads is actuatable to radially extend away from the housing by rotating about an axis that is substantially parallel to a longitudinal axis of the housing. 
     
     
         3 . The system of  claim 1  wherein the valve and the controller are collectively operable to simultaneously actuate each of the plurality of steering pads by disengaging the valve. 
     
     
         4 . The system of  claim 1  wherein the back-reaming bit comprises a plurality of cutting elements. 
     
     
         5 . The system of  claim 4  wherein each of the plurality of cutting elements comprises:
 a substrate coupled to the corresponding steering pad; and 
 a cutting layer coupled to the substrate. 
 
     
     
         6 . The system of  claim 4  wherein each of the plurality of steering pads comprises at least one of the plurality of cutting elements. 
     
     
         7 . The system of  claim 6  wherein simultaneously actuating each of the plurality of steering pads to substantially centralize the RSS relative to the wellbore urges at least one of the plurality of cutting elements on each of the plurality of steering pads into contact with the sidewall of the wellbore. 
     
     
         8 . The system of  claim 1  wherein each of the plurality of steering pads is actuatable to radially extend away from a retracted position toward an extended position. 
     
     
         9 . The system of  claim 8  wherein each of the plurality of steering pads is lockable in the extended position. 
     
     
         10 . The system of  claim 1  wherein the cutting elements are disposed in an uphole portion of each of the plurality of steering pads and not in a downhole portion of each of the plurality of steering pads. 
     
     
         11 . An apparatus, comprising:
 a drill string disposed within a wellbore that extends from a wellsite surface to a subterranean formation;   a drill bit; and   a rotary steerable system (RSS) coupled between the drill string and the drill bit, wherein the RSS comprises:
 a plurality of steering pads spaced circumferentially apart around a perimeter of the RSS; 
 a valve operable to sequentially actuate the plurality of steering pads; and 
 a back-reaming bit comprising a plurality of cutting elements, wherein each of the plurality of steering pads comprises at least one of the plurality of cutting elements. 
   
     
     
         12 . The apparatus of  claim 11  wherein each of the plurality of cutting elements comprises:
 a substrate coupled to a corresponding one of the plurality of steering pads; and 
 a cutting layer coupled to the substrate. 
 
     
     
         13 . The apparatus of  claim 12  wherein:
 the substrate substantially comprises tungsten carbide; and 
 the cutting layer substantially comprises polycrystalline diamond. 
 
     
     
         14 . The apparatus of  claim 11  further comprising a controller, wherein the valve and the controller are collectively operable to sequentially actuate the plurality of steering pads to operatively urge the RSS away from a longitudinal axis of the wellbore. 
     
     
         15 . The apparatus of  claim 14  wherein the valve and the controller are collectively further operable to simultaneously actuate each of the plurality of steering pads to operatively urge at least one of the plurality of cutting elements on each of the plurality of steering pads into contact with a sidewall of the wellbore. 
     
     
         16 . The apparatus of  claim 11  not comprising a reaming tool, component, or feature disposed between the drill string and the RSS. 
     
     
         17 . The apparatus of  claim 11  not comprising a reaming tool, component, or feature disposed between the drill string and the drill bit, other than the back-reaming bit formed by the plurality of cutting elements comprised by corresponding ones of the plurality of steering pads. 
     
     
         18 . A method, comprising:
 conveying apparatus within a wellbore that extends from a wellsite surface to a subterranean formation, wherein the apparatus comprises a drill string, a drill bit, and at a rotary steerable system (RSS) coupled between the drill string and the drill bit, and wherein the RSS comprises:
 a plurality of steering pads spaced circumferentially apart around a perimeter of the RSS, wherein each of the plurality of steering pads carries at least one of a plurality of cutting elements; 
 a valve operable for sequentially actuating the steering pads; and 
 a controller; 
   rotating the drill string, thereby rotating the RSS and the drill bit, while operating at least one of the valve and the controller to sequentially actuate the plurality of steering pads to operatively urge the RSS and the drill bit away from a longitudinal axis of the wellbore; and   rotating the drill string, thereby rotating the RSS and the drill bit, while operating at least one of the valve and the controller to simultaneously actuate each of the plurality of steering pads to operatively urge at least one of the plurality of the cutting elements on each of the plurality of steering pads into contact with a sidewall of the wellbore.   
     
     
         19 . The method of  claim 18  wherein:
 rotating the drill string while operating at least one of the valve and the controller to sequentially actuate the plurality of steering pads to operatively urge the RSS and the drill bit away from a longitudinal axis of the wellbore comprises:
 rotating the drill string while operating at least one of the valve and the controller to sequentially actuate the plurality of steering pads to operatively urge the RSS and the drill bit in a first azimuthal direction away from the longitudinal axis of the wellbore; and 
 
 the method further comprises:
 rotating the drill string while operating at least one of the valve and the controller to sequentially actuate the plurality of steering pads to operatively urge the RSS and the drill bit in a second azimuthal direction away from the longitudinal axis of the wellbore, wherein the first and second azimuthal directions differ by at least about twenty degrees. 
 
 
     
     
         20 . The method of  claim 19  wherein:
 rotating the drill string while operating at least one of the valve and the controller to sequentially actuate the plurality of steering pads to operatively urge the RSS and the drill bit in the first azimuthal direction away from the longitudinal axis of the wellbore creates a first wellbore section extending in a first wellbore direction; 
 rotating the drill string while operating at least one of the valve and the controller to sequentially actuate the plurality of steering pads to operatively urge the RSS and the drill bit in the second azimuthal direction away from the longitudinal axis of the wellbore creates a second wellbore section extending in a second wellbore direction; and 
 rotating the drill string while operating at least one of the valve and the controller to simultaneously actuate each of the plurality of steering pads to operatively urge at least one of the plurality of the cutting elements on each of the plurality of steering pads into contact with the sidewall of the wellbore includes back-reaming the first and second wellbore sections.