Steerable downhole drilling tool

Abstract

A drill bit has a bit body that has a cutting structure mounted on a base section. The cutting structure has a plurality of roller cones, a plurality of fixed blades, or both. The base section has a plurality of pad that are extendable from a circumference of the base section. The base section is connected to a threaded pin connectable with a lower end of a drill string.

What is claimed is: 
     
         1 . A drill bit, comprising:
 a bit body comprising a cutting structure mounted on a base section,   wherein the cutting structure comprises a plurality of roller cones, a plurality of fixed blades, or both, and   wherein the base section comprises a plurality of pad that are extendable from a circumference of the base section.   
     
     
         2 . The drill bit of  claim 1 , wherein the base section is connected to a threaded pin connectable with a lower end of a drill string. 
     
     
         3 . The drill bit of  claim 1 , wherein the drill bit has a diameter larger than 17.5″ and two pads are installed along the circumference of the base section of the drill bit. 
     
     
         4 . The drill bit of  claim 1 , wherein the drill bit has a diameter between 9.5″ and 17.5″, three pads are installed along the circumference of the base section of the drill bit. 
     
     
         5 . The drill bit of  claim 1 , wherein the drill bit has a diameter between 4.75″ and 9.5″, four or six or eight pads are installed along the circumference of the base section of the drill bit. 
     
     
         6 . The drill bit of  claim 1 , further comprising a plurality of pistons, each of the plurality of piston is connected to and able to be activated by a hydraulic system or by an electric motor. 
     
     
         7 . The drill bit of  claim 1 , wherein each of the plurality of pistons, when activated, push against and extend one of the plurality of pads out from the circumference of the base section. 
     
     
         8 . The drill bit of  claim 7 , wherein the plurality of pads are retracted from the extended state when the piston is not activated. 
     
     
         7 . The downhole drilling system of  claim 7 , wherein each of the plurality of pads has a shape of a rectangular block. 
     
     
         8 . The downhole drilling system of  claim 7 , wherein each of the plurality of pads, in an extended state, is at an angle with an axial direction of the drill bit. 
     
     
         9 . A downhole drilling system, comprising:
 a drill string having a bottom hole assembly (BHA) disposed at a lower part thereof;   a kelly drive configured to deliver the drill string into a borehole;   a top drive configured to rotate the drill string; and   a controller,   wherein the BHA comprises a drill bit of  claim 1  disposed at an end portion of the BHA, a downhole motor, and a measurement sub configured to measure subsurface formation properties and operational parameters.   
     
     
         10 . The downhole drilling system of  claim 9 , each of the plurality of pistons is connected to and able to be activated by a hydraulic system or by an electric motor. 
     
     
         11 . The downhole drilling system of  claim 10 , wherein the activation of each of the plurality of the pistons is commanded by the controller.