Hole opener and method for drilling

Abstract

The present document describes a drill-bit which achieves both the rigidity and a fast rate of penetration. The drill-bit comprises a cone shaped central portion comprising a plurality of ribs protruding from the central portion and defining a plurality of blades. The blades are curved along a direction of a longitudinal axis of the cone to facilitate insertion into a hole when rotating in a first direction, and exit from the hole when rotating in a second direction opposite the first direction. The drill-bit comprises a plurality of polycrystalline diamond cutters (PDC) on the blades provided in a first position for cutting the hard structure as the drilling-bit rotates in the first direction, and a plurality of up-drill PDC cutters provided in a second position for cleaning the hole as the drill-bit rotate in the second direction to exit the hole.

1 . A drill-bit for drilling holes in a hard structure, the drill-bit comprising:
 a cone shaped central portion defining an upper end and a lower end;   a plurality of ribs protruding from the central portion and defining a plurality of blades, the blades being curved along a direction of a longitudinal axis of the cone to facilitate insertion into a hole when rotating in a first direction, and exit from the hole when rotating in a second direction opposite the first direction;   a first set of polycrystalline diamond cutters PDC provided on the blades for cutting the hard structure as the drilling-bit rotates in the first direction.   
     
     
         2 . The drill-bit of  claim 1 , wherein the blades comprise:
 an upper portion comprising the first set of PDC cutters along an edge thereof for cutting the hard structure as the drilling-bit rotates in the first direction;   a middle portion which is substantially parallel to the longitudinal axis for stabilizing the drill-bit when rotating within the hole and for refining an inner surface of the hole; and   a lower portion defining a slope starting from the middle portion and ending at the lower end.   
     
     
         3 . The drill-bit of  claim 2 , further comprising one or more sets of back-up PDC cutters provided in parallel to or adjacent the first set of PDC cutters on one or more of the blades for improving a rigidity of the blades against the hard structure. 
     
     
         4 . The drill-bit of  claim 2 , further comprising one or more up-drill PDC cutters positioned between or adjacent the middle portion of the drill-bit and the lower portion of the drill-bit for cleaning the hole as the drill-bit rotates in the second direction to exit the hole. 
     
     
         5 . The drill-bit of  claim 1 , wherein the PDC cutters comprise a top layer of polycrystalline diamond integrally sintered onto a tungsten carbide substrate. 
     
     
         6 . The drill-bit of  claim 1 , wherein the drill-bit is hollow on at least one of the lower end and upper end and defines an inner thread for connecting to a pipe of a drilling-rig. 
     
     
         7 . The drill-bit of  claim 6 , further comprising a plurality of nozzles fluidly connected to the pipe for cleaning the blades and the PDC cutters. 
     
     
         8 . The drill-bit of  claim 7 , wherein the nozzles are provided in a plurality between adjacent blades, the nozzles being positioned to clean at least the upper portion and the middle portion of the drill-bit. 
     
     
         9 . The drill-bit of  claim 8 , wherein a set of nozzles is provided adjacent each edge of each blade to have two sets of nozzles between adjacent blades. 
     
     
         10 . A method for making a hole in a hard structure comprising:
 connecting the drill-bit of  claim 1  to the pipe of a drilling-bit;   applying pressure on the drill-bit;   rotating the drill-bit in a first direction to penetrate the hard structure.   
     
     
         11 . The method of  claim 10 , further comprising rotating the drill-bit in a second direction opposite the first direction to exit the hole. 
     
     
         12 . A drill-bit for drilling holes in a hard structure, the drill-bit comprising:
 a cone shaped central portion defining an upper end and a lower end;   a plurality of ribs protruding from the central portion and defining a plurality of blades, the blades being curved along a direction of a longitudinal axis of the cone to facilitate insertion into a hole when rotating in a first direction, and exit from the hole when rotating in a second direction opposite the first direction:   a first set of pockets provided on the blades for receiving a first set of polycrystalline diamond cutters (PDC) the pockets of the first set being positioned to allow the PDC cutters received therein to cut the hard structure as the drilling-bit rotates in the first direction to open the hole.   
     
     
         13 . The drill-bit of  claim 12 , wherein each blade comprises:
 an upper portion comprising the first set of pockets along an edge thereof;   a middle portion which is substantially parallel to the longitudinal axis for stabilizing the drill-bit when rotating within the hole and for refining an inner surface of the hole; and   a lower portion defining a slope starting from the middle portion and ending at the lower end of the drill-bit.   
     
     
         14 . The drill-bit of  claim 13 , wherein a thickness of the lower portion is substantially null at the lower end of the drill-bit. 
     
     
         15 . The drill-bit of  claim 13 , further comprising one or more up-drill PDC cutters positioned between or adjacent the middle portion and the lower portion of the drill-bit for cleaning the hole as the drill-bit rotates in the second direction to exit the hole. 
     
     
         16 . The drill-bit of  claim 12 , wherein the drill-bit is hollow on at least one of the lower end and upper end and defines an inner thread for connecting to a pipe of a drilling-rig. 
     
     
         17 . The drill-bit of  claim 16 , further comprising a plurality of nozzles fluidly connected to the pipe for cleaning the blades and the PDC cutters. 
     
     
         18 . The drill-bit of  claim 17 , wherein the nozzles are provided in a plurality between adjacent blades, the nozzles being positioned to clean at least the upper portion and the middle portion of the drill-bit. 
     
     
         19 . The drill-bit of  claim 18 , wherein a set of nozzles is provided adjacent each edge of each blade to have two sets of nozzles between adjacent blades. 
     
     
         20 . The drill bit of  claim 12 , further comprising an external layer of Tungsten Carbide for allowing the drill-bit to cut all rock formations irrespective of a varying hardness of the rock formations.