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
  • E21B10/36—Percussion drill bits
• • 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
  • E21B4/00—Drives for drilling, used in the borehole
  • E21B4/06—Down-hole impacting means, e.g. hammers
• • 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
  • E21B7/00—Special methods or apparatus for drilling
  • E21B7/04—Directional drilling
  • E21B7/06—Deflecting the direction of boreholes
  • E21B7/067—Deflecting the direction of boreholes with means for locking sections of a pipe or of a guide for a shaft in angular relation, e.g. adjustable bent sub

Definitions

• the present invention relates to horizontal directional drilling and, in particular, to a drill bit for a directional drilling tool.
• the directional drilling equipment usually comprises a percussion drill bit operable through a drill string and includes a steering device so that the drill bit can be steered in a desired substantially horizontal direction below and along the route of roads and streets, and under river beds, roads and the like.
• a drill string incorporating a percussion hammer to apply axial impact forces to the drill bit, is utilised to drill an initial pilot hole of a smaller diameter (for example 133 mm) than the diameter of the ultimate passage desired.
• the ultimate drill passage may have a diameter of anything from 200 mm to 760 mm depending upon the size of the cables, pipes or conduits to be inserted in the drilled passageway.
• the percussion drill bit has a head portion formed with an axially extending shank.
• the head portion of the bit is similar to that of a normal percussion drill bit, but with a portion machined off one side of the bit to provide a slant face for steering purposes.
• the slant face is provided with flat- wear carbides, although these are not essential.
• Figures 1, 2, 5a and 5b show the slant- faced bit in assembly with the hammer and a locating device known as a sonde.
• the sonde is located in a locator housing in a fixed axial and angular location.
• the sonde sends out a signal which provides data at the surface which indicates depth, angle or pitch and angular position of the drill tool.
• the locator housing is threadably connected to a hammer with the slant-faced bit located at the end of the hammer.
• the connection between the locator housing and the hammer can be made using either a bent or a straight sub.
• a bent sub allows for more aggressive steering of the tool.
• the bend is typically of the order of 1 to 3 degrees.
• the bit is assembled so that the slant face is located at the six o'clock position of the sonde.
• the sonde locator In order to steer the hammer in an upward direction, the sonde locator is checked so that its angular position reads six o'clock, indicating that the slant face of the bit is at the six o'clock position.
• the assembly is rocked about this point by about 60 degrees (or two "hours") either side of the initial point as the hammer drills forward, causing the hammer to steer upwards.
• normal rotation is applied and the system drills straight.
• a percussion drill bit for directional drilling tools comprising:
• head portion of the drill bit is formed with a plurality of slant faces arranged symmetrically about the head portion.
• slant faces is used herein to indicate that the faces are angled with respect to an elongate axis of the bit.
• slant faces are arranged radially around the head portion of the bit in such a way that the positioning of the slant faces is symmetrical about at least one axis through the head portion of the bit.
• the slant faces are spaced at regular intervals around the circumference of the head portion of the bit.
• each of the slant faces comprises a substantially planar surface angled with respect to an elongate axis of the bit.
• each of the slant faces may comprise a plurality of contiguous planar surfaces, wherein each of the planar surfaces is angled with respect to the elongate axis of the bit.
• Each of the planar surfaces may be continuous or non-continuous. The angle at which the slant faces are arranged with respect to the elongate axis of the bit may be selected depending on how aggressively the bit is required to steer. The less acute the angle of the slant faces, the more aggressively the bit may be steered.
• An advantage of the present invention is that, because a plurality of slant faces are provided, the forces on the bit due to steering can be spread over the circumference of the bit by indexing the bit in the chuck. In this way, each of the slant faces may be used in turn to steer the bit, so that no one area of the bit shank is subjected to extreme bending stresses, thereby increasing the lifetime of the bit.
• the head portion of the drill bit is preferably formed with an odd number of slant faces. This allows the slant faces to be arranged around the circumference of the bit such that carbides may be provided diametrically opposite to each slant face to allow cutting of material in the steering direction, while maintaining symmetry of the bit. For example, if the tool is to be steered upwards, the bit may be positioned such that one of the slant faces is at the six o'clock position in the drill assembly, that is, at the bottom of the assembly. In order to drill upwards, it is preferable that carbides are provided at the top of the drill bit, that is, at the 12 o'clock position, to allow the drill to move upwards.
• the head portion of the drill bit is provided with three slant faces.
• the slant faces may be provided with a hard-wearing material to improve the wear resistance of the slant faces.
• the hard-wearing material is provided in the form of flat wear carbides.
• a layer of a hard-wearing material may be applied to the slant faces.
• strips of the material may be applied to the slant faces.
• the engagement means comprises a plurality of axially extending splines on the shank slideably engageable with complementary splines formed on the drive chuck.
• the number of splines is an integer multiple of the number of slant faces provided on the bit.
• Figure 1 is a side elevation of a known horizontal directional drilling tool
• Figure 2 is a side elevation of an alternate embodiment of a known horizontal directional drilling tool
• Figure 3 is a side elevation of a horizontal directional drilling tool in accordance with an embodiment of the invention
• Figure 4 is a side elevation of a horizontal directional drilling tool in accordance with an alternate embodiment of the invention.
• Figure 5a is an isometric view of the drilling tool of Figure 1;
• Figure 5b is an isometric view of the drilling tool of Figure 2;
• Figure 5c is an isometric view of the drilling tool of Figure 3;
• Figure 5d is an isometric view of the drilling tool of Figure 4.
• Figure 6 is an isometric view of the percussion drilling bit of the drilling tool of Figures 1 and 2;
• Figure 7 is an isometric view of a percussion drilling bit according to an embodiment of the invention.
• Figure 8 is an isometric view of a percussion drilling bit according to an alternate embodiment of the invention.
• Figure 9 is a plan view of the drilling bit of Figure 7.
• Figure 10 is a plan view of the drilling bit of Figure 8.
• the drill bit 1 for a directional drilling tool 10.
• the drill bit 1 comprises a head portion 2 formed with an axially extending shank 3.
• the head portion has a front cutting face 6, which is provided with a plurality of carbide buttons or inserts 7.
• Gauge row carbides 8 are provided at the periphery of the bit.
• the drill bit further comprises twelve axially extending splines 4 on the stub shank 3 slideably engageable with complementary splines formed on a drive chuck.
• the head portion 2 of the drill bit 1 is formed with three slant faces 5 arranged symmetrically about the head portion 2.
• the three slant faces 5 are equally spaced around the circumference of the head portion 2 of the bit.
• Each of the slant faces 5 is provided with a plurality of flat wear carbides 9.
• the slant faces 5 are inclined at an angle with respect to the elongate axis X-X of the bit.
• Each of the slant faces 5 comprises two contiguous planar surfaces 5 a and 5b, and each of the planar surfaces 5 a, 5b is angled with respect to the elongate axis of the bit.
• each of the planar surfaces is non-continuous, in the sense that each of the surfaces is interrupted by a channel 15 in the bit head 2.
• the slant faces 5 are arranged radially around the head portion 2 of the bit 1 at regular intervals in such a way that the positioning of the slant faces is symmetrical about axis Y-Y.
• the slant faces can be arranged around the circumference of the bit such that gauge row carbides 8 are provided diametrically opposite to each slanted face.
• FIG. 8 and 10 An alternate embodiment of the percussion drill bit of the invention is shown in Figures 8 and 10.
• a fewer number of larger carbides 8 are provided on the gauge. This allows larger slant faces 5 to be machined off the bit head 2, so that each of the slant faces has a larger surface area.
• FIGs 3, 4, 5c and 5d show the percussion drill bit 1 according to the present invention in assembly with a hammer and a locating device known as a sonde.
• a directional drilling tool 10 comprises a locator housing 11, a sub 12 and a hammer 13.
• the drill bit 1 is disposed at a forward end 14 of the hammer 13.
• the sonde is located in the locator housing 11 in a fixed axial and angular location, as described above in relation to Figures 1 and 2.
• the sonde sends out a signal which provides data at the surface which indicates depth, angle or pitch and angular position of the drill tool.
• the locator housing 11 is threadably connected to a hammer 13 with the symmetrical slant-faced bit located at the end 14 of the hammer.
• connection between the locator housing and the hammer can be made using either a bent or a straight sub 12.
• a bent sub allows for more aggressive steering of the tool. As shown in Figure 3, the bend is typically of the order of 1 to 3 degrees.
• the bit is assembled so that one of the slant faces 5 is located at the six o'clock position of the sonde.
• the sonde locator In order to steer the hammer 13 in an upward direction, the sonde locator is checked so that its angular position reads six o'clock, indicating that a slant-face is at the six o'clock position.
• the assembly is rocked by about 60 degrees (or 2 "hours") either side of this initial position as the hammer drills forward, causing the hammer to steer upwards.
• normal rotation is applied and the system drills straight.
• the bit In order to distribute the forces on the bit 1 due to steering, the bit may be indexed in the chuck. In this way, each of the slant faces 5 may be used in turn to steer the bit, so that no one area of the bit shank is subjected to extreme bending stresses, thereby increasing the lifetime of the bit.

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

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• 2012
  • 2012-04-05 IE IES20120176A patent/IES86164B2/en not_active IP Right Cessation
• 2013
  • 2013-04-03 CA CA2869019A patent/CA2869019A1/en not_active Abandoned
  • 2013-04-03 US US14/390,478 patent/US20150176334A1/en not_active Abandoned
  • 2013-04-03 EP EP13716753.2A patent/EP2855824A2/de not_active Withdrawn
  • 2013-04-03 WO PCT/EP2013/057046 patent/WO2013150078A2/en active Application Filing

Non-Patent Citations (1)

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