Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/64—Drill bits characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe
  • E21B10/66—Drill bits characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe the cutting element movable through the drilling pipe and laterally shiftable

Definitions

• the present invention is related to earth drilling equipment, and particularly to down hole, pneumatic, percussive hammer drilling systems.
• underreamers are used for the formation of radially enlarged areas extending about a pilot bit for insertion of a casing.
• Eccentrically mounted underreamers which include an arm which travels in an orbit for underreaming
• eccentrically mounted underreamers can be diverted off-axis if the underreamer encounters rock fragments, buried metal objects, etc.
• underreaming equipment utilizes three bit mounted plates which are outwardly displaceable, but which incorporate a total working surface which is substantially less than the perimeter of the bore. Such undersized plates are subject to excessive wear and result in slow drilling operation. Underreaming can also be achieved by use of a crown or
• the present invention is embodied in a reverse circulation system which addresses the shortcomings of the prior art .
• each underreamer arm includes a strengthening boss .
• the strengthening boss includes axial bearing surfaces which engage corresponding axial surfaces
• the bearing surfaces of the arm bosses and the bits include surfaces shaped to extend the arms as
• the pilot bit is rotated relative to the pilot bit.
• Surfaces are also provided for locking the arm in its
• the locking surfaces disengage and the arm can be retracted without vertical movement of the driver.
• the flow of exhaust air is routed through porting in the bit assembly into the central evacuation tube.
• a second flow of compressed air may also be provided to continually flush the perimeter
• the perimeter flushing air is received from compressed air introduced at the well-head to pressurize the casing.
• FIG. 1 is a partial cross-sectional view of a drilling assembly according to the present invention.
• FIG. 2 is an expanded partial cross-sectional view of the assembly shown in FIG. 1, showing the power head assembly, compressed air inlet collar, and the upper terminus of the dual wall pipe assembly.
• FIG. 3 is an expanded cross-sectional view of the assembly shown in FIG. 1, showing the casing driver in
• FIG. 4 is an expanded cross-sectional view of assembly shown in FIG. 1, showing the dual wall pipe assembly and the box and back head assembly connecting the lower terminus of the dual wall pipe assembly to the down-hole pneumatic hammer .
• FIG. 5 is a cross-sectional view of the down-hole pneumatic hammer assembly, including the bit assembly.
• FIG. 5A is a perspective view of an alternative design for the hammer barrel of the down-hole pneumatic hammer assembly.
• FIG. 6A is an exploded perspective view of a first embodiment of a bit assembly according to the present invention.
• FIG. 7A is a perspective view of the pilot bit on the embodiment of FIG. 6A.
• FIG. 7B is a bottom view of the pilot bit shown in FIG. 7A.
• FIG. 8 is a perspective view of an underreamer arm used in the embodiment shown in FIG. 6A.
• FIG. 9A is an end view of the underreamer arm shown in
• FIG. 8 is an outer side view of the underreamer arm
• FIG. 10 is a bottom view of the bit driver of the embodiment shown in FIG. 6A, showing the axial surfaces which define the recesses which receive the underreamer arms, and the axial surfaces which bear against the underreamer arms for extension and retraction.
• FIG. 11 is a bottom view of the bit driver in a second embodiment of the invention.
• FIG. 12 is a bottom view of an underreamer arm of the embodiment referred to in FIG. 11.
• FIG. 13 is a bottom view of the arms depicted in FIG. 12 mounted in their retracted position on the bit driver
• FIG. 14 is a top view of a pilot bit for use with the bit driver and underreamer arms depicted in FIG. 13.
• Fig. 15 is a bottom view of the pilot bit depicted in FIG. 14.
• FIG. 16 is the bit driver and underreamer arms shown in FIG. 13 with the underreamer arms in their extended positions.
• Fig. 17 is an enlarged partial view of the bit driver and underreamer arm shown in FIG. 13.
• FIG. 18 is a partial cutaway bottom view of the bit assembly depicted in FIGS. 11-17 showing the compressed air flow path.
• a reverse circulation drilling system shown generally at 10, includes a head assembly 11, a dual wall pipe assembly 12, and a down hole pneumatic hammer 13 within a bore casing 14.
• head assembly 11 includes a casing driver 15 for driving the bore casing 14 downwardly as the bit advances, and a power head assembly 16 of standard design for rotating the bore casing 14 it is driven downwardly.
• Casing driver 15 includes an annular hammer 17 which reciprocates vertically as compressed air is alternatively admitted to chambers above and below hammer 17.
• Hammer 17 impacts on anvil 18, which in turn impacts on casing cap 19.
• Casing cap 19 is sealed against the inner surface of bore casing 14 to permit pressurization, through port 20, of bore casing 14 between casing cap 19 and down hole hammer assembly 13.
• Power head assembly 16 is connected to anvil 18 through linkage assembly 21 to impart rotation to the dual pipe assembly and the down hole hammer. Power head assembly 16 is of a design
• central member 22 which is threaded onto the upper end of dual wall pipe assembly 14, includes a central bore in communication with the dual wall pipe assembly to extend the debris discharge
• the joint of central member 22 and the dual wall pipe 14 includes a port 23 for admitting air to the annulus 24 between the inner wall 25 and the outer wall 26 of the dual wall pipe assembly.
• Collar 27 is mounted around the joint, and includes air inlet 28, through which compressed air is admitted into the dual wall pipe assembly for driving the down hole hammer as further described below.
• An elbow 29 is rotatably mounted and sealed to the upper end of central member 22.
• Elbow 29, central member 22 and the inner wall 25 of dual wall pipe assembly 14 together form a central drilling debris discharge tube for continuously discharging drilling debris from the down hole hammer as will also be described more fully below.
• dual wall pipe assembly 12 is assembled from individual segments, each of which includes
• Each segment includes a threaded male connector 33 and a threaded female connector 35 at opposite ends.
• Male connector 14 and female connector 15 each includes air ports 36 and 37
• dual wall pipe assembly 11 is threaded in to central member 22 of power head 16.
• dual wall pipe assembly 11 is connected to the box 38, which in turn is threaded into back head 40 of down-hole hammer 13.
• Ports 42 an 44 communicate with annulus 24 of the dual wall pipe assembly to route compressed air therefrom into the down hole hammer .
• down-hole hammer 13 includes box 38 threaded onto back head 40.
• a sleeve 41 and a hammer barrel 42 are threaded into back head 40.
• a centrally located discharge tube 43 is pressed into sleeve 41.
• a wear sleeve 44 is fitted around hammer barrel 40, and press fitted over ring 45 and onto shoulder 46 of back head 40.
• Sleeve 41 and barrel 42 define an annular upper
• bit driver 52 abuts bit driver 52, and also includes a perimetrical lip 54 which engages wear sleeve 44 to center barrel 42 in the wear sleeve.
• Hammer 53 is slidingly fitted into barrel 42 for reciprocation.
• Bit driver 52 is
• the key-keyway assembly permits
• a bit assembly according to the present invention is
• FIG. 6 a bit assembly
• bit driver 52 includes bit driver 52, pilot bit 82, and arms 88a-c.
• Pilot bit 82 includes an upper shank 83 having a recessed
• Lower portion 86 includes three peripheral
• Hardened drilling buttons preferably
• pilot bit made of a carbide material, are mounted on the peripheral and bottom surfaces of the pilot bit (FIG. 7) .
• Arms 88a- c are nested atop pilot bit 82, and slide thereon in an prescribed arcuate path as will be described.
• Each of the arms includes a raised boss 89 which is received into corresponding recess 90 of bit driver 52 (FIG. 10) .
• Raised boss 89 serves several functions. First, impact forces from the hammer are transmitted downwardly to the pilot bit 82 through bit driver 52, boss 89, and arm 88. Second, boss 89 is received and retained in recess 90, where it rotates through a limited arc to extend and retract arm 88. With arm 88 in its retracted position, surface 91 is adjacent camming surface 85a. in this configuration, the overall diameter of the bit assembly is less than the inner diameter of the bore casing,
• FIG. 5A (FIG. 5A) , and discharged through the bit assembly into central evacuation tube 43, carrying with it drilling
• port 91 is provided through
• pilot bit 104 advances into the ground with the underreamer arms locked in a deployed position below and radially beyond the advancing end of the casing at C. Casing movement is facilitated by the relatively large underreamed area, and if required, by the casing driver 15. In one embodiment shown in FIGS. 1 and 3, if the drill bit assembly advances
• linkage 21 operates a valve to provide compressed air to the pneumatic hammer 17 and associated porting casing driver 15.
• the bit assembly also includes a bit driver 100, arms 102 a-c, and pilot bit 104, which are fitted together as described in the previous embodiment shown in FIG 6.
• compressed exhaust air from port 80 is routed through internal ports in the bit driver, arms and pilot bit.
• hammer exhaust air from port 80 flows into and through bit driver 100 via ports 106 a-c.
• the hammer exhaust air then flows through ports 108 a-c formed in arms 102 a-c respectively (FIG. 12) .
• the arms are shown mounted on the bit driver in their closed and retracted positions. Exhaust air from ports 108 a-c flows into ports 110 a-c in pilot bit 104 (FIGS. 14, 15), through channels 112 a-c, ports 114 a-c, and into central
• arms 102a-c respectively) are partially offset from ports
• ports 110 a-c are offset from ports 108 a-c (through the pilot bit)
• channels 112 a-c are provided in the
• pilot bit 104 also includes axial recesses 114 a-c, and
• transverse channels 116 a-c Recesses 114 a-c and
• channels 116 a-c provide a path for the discharge of

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Earth Drilling (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=25406839

Family Applications (1)

Country Status (9)

Cited By (4)

Citations (3)

Family Cites Families (1)

• 1998
  • 1998-07-17 CA CA002296470A patent/CA2296470A1/en not_active Abandoned
  • 1998-07-17 CN CNB988092085A patent/CN1263937C/zh not_active Expired - Fee Related
  • 1998-07-17 AU AU84873/98A patent/AU755442C/en not_active Ceased
  • 1998-07-17 KR KR1020007000564A patent/KR20010021997A/ko not_active Application Discontinuation
  • 1998-07-17 BR BR9815553-9A patent/BR9815553A/pt not_active Application Discontinuation
  • 1998-07-17 EP EP98935684A patent/EP0996810A1/en not_active Withdrawn
  • 1998-07-17 JP JP2000503316A patent/JP2001510256A/ja active Pending
  • 1998-07-17 WO PCT/US1998/014651 patent/WO1999004130A1/en not_active Application Discontinuation
• 2001
  • 2001-02-20 HK HK01101223A patent/HK1030253A1/xx not_active IP Right Cessation

Patent Citations (3)

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