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
  • E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts
  • E21B10/56—Button-type inserts
  • E21B10/567—Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts
  • E21B10/5676—Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts having a cutting face with different segments, e.g. mosaic-type inserts
• • 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
  • E21B29/00—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
  • E21B29/06—Cutting windows, e.g. directional window cutters for whipstock operations

Definitions

• THIS invention relates to tool inserts and more particularly tool inserts which can be used as cutting elements in rotary drilling bits intended for subterranean rock drilling.
• diamond compacts also known as PCD
• PCD diamond compacts
• cutters in drilling operations is well known due to the high abrasion resistant properties of diamond cutters. It is also well established that diamond cutters cannot be used satisfactorily for milling or drilling through ferrous substrates such as steel. Therein lies a problem in the use of diamond cutters in certain down the hole drilling operations, particularly with regard to subterranean directional drilling, such as drilling horizontally into a rockbed from an underground location in a vertical borehole or shaft.
• a steel casing is typically positioned down the vertical borehole or shaft, creating a lining therefor in the region requiring horizontal drilling.
• a deflector which is positioned adjacent the position where horizontal drilling is to be carried out. The function of the deflector, which is generally wedge-shaped, is to cause the drill to change direction and begin milling through the steel casing to create a window to the bedrock.
• tungsten carbide cutters are typically used in the drill bit to mill through the steel casing. Once through the casing, the tungsten carbide inserts have to be replaced with abrasive resistant cutters such as diamond cutters in order to drill into the bedrock. This means that the drill bit has to be removed and replaced with an appropriate bit. As the drill strings that have to be removed are very long, this is a time consuming exercise. that results in costly downtime.
• a tool insert comprises:
• the layer of ultra-hard abrasive material having a side surface and a top surface, a portion of the periphery of the top surface of the ultra- hard abrasive material providing a primary cutting edge for the tool insert;
• a protective layer a surface of the protective layer being bonded to the top surface and/or the side surface of the ultra-hard abrasive material so as to protect the primary cutting edge thereof, a periphery of the protective layer providing a secondary cutting edge for the tool insert, the depth of the protective layer being selected so as to be sufficient to protect the primary cutting edge whilst cutting, milling or drilling a window through a first substance, such as a casing or lining of a borehole or shaft, but to expose the primary cutting edge upon encountering a second substance, such as a rockbed.
• a first substance such as a casing or lining of a borehole or shaft
• a method of drilling a horizontal or angled hole in a subterranean rock formation includes the steps of: 1) preparing the. site for horizontal or angled drilling by a) using an existing borehole or, if not available, drilling a borehole into a subterranean rock formation to an appropriate depth and b) lining the borehole, at least in the region where horizontal or angled drilling is to take place, with a casing or lining having a passage and a deflector means mounted in the passage;
• each cutting tool insert comprising a substrate, a layer of ultra-hard abrasive material bonded to the substrate, the ultra-hard abrasive material providing a primary cutting edge for the tool insert, and a protective layer for protecting the primary cutting edge and for providing a secondary cutting edge;
• the depth of the protective layer is such as to protect the primary cutting edge whilst milling through the casing or lining and to expose the primary cutting edge upon encountering the subterranean rock formation.
• the above method can also be used for the drilling of multiple directional holes from a central vertical borehole.
• Figure 1 is a schematic sectional side view of a rotary drill bit in a subterranean rock drilling operation
• Figure 2 is a sectional side view of a first embodiment of a tool insert of the invention
• Figure 3 is a plan view of the tool insert of figure 2;
• Figure 4 is a sectional side view of a second embodiment of a tool insert of the invention.
• Figure 5 is a sectional side view of a third embodiment of a tool insert of the invention.
• Figure 6 is a plan view of the tool insert of Figure 5;
• Figure 7 is a sectional side view of a fourth embodiment of a tool insert of the invention.
• Figure 8 is a plan view of the tool insert of Figure 7;
• Figure 9 is a sectional side view of a fifth embodiment of a tool insert of the invention.
• Figure 10 is a plan view of the tool insert of Figure 9. DESCRIPTION OF EMBODIMENTS
• a drill assembly 10 consists of a rotary drill string 12 and a rotary drill bit 14, of the drag bit kind in this case.
• the drill bit 14 is directed down a passage 16 within a steel tubular casing 18.
• the steel casing 18 is anchored in a borehole or shaft 20 drilled into a subterranean bedrock or rock formation 22.
• a deflector 26 which is attached to the casing 18 and which has previously been positioned adjacent the region 'X', causes the bit 14 to change direction in this manner.
• the deflector 26 is supported by an anchor 28.
• the layer of ultra-hard abrasive material will generally be a layer of PCD, although under appropriate conditions PCBN may also be used.
• the layer may also be a layer of diamond produced by chemical vapour deposition, called CVD diamond.
• the substrate of the tool insert will generally be a cemented carbide substrate. Such substrates are well known in the art and are generally cemented tungsten carbide substrates.
• the protective layer which may be an extension of the substrate or a separate layer, will also generally be of cemented tungsten carbide, although it may be of a different grade to that of the substrate. In certain instances, the' protective layer may be formed of tool steel or other appropriate material suited to milling through steel or other material used for the casing or lining.
• a cemented carbide substrate 40 has a planar base surface 42 and an upper surface 44.
• a centrally located recess 46 is formed in the upper surface 44.
• the recess 46 is surrounded by an annular region 48 and has a surface 50. Although the recess 46 is centrally located in this embodiment, it could also be positioned off centre.
• the recess 46 is filled with diamond particles. Thereafter, the diamond- filled substrate 40 is placed in a reaction capsule and the reaction capsule placed in the reaction zone of a conventional high pressure/high temperature apparatus. The capsule is exposed to conditions of high pressure and temperature suitable to produce a diamond abrasive compact (PCD) 52. Under these conditions the PCD 52 will form and bond to the cemented carbide substrate over the entire surface which defines the recess 46. A cutting edge 54, the primary cutting edge of the tool insert, is defined by the periphery of the PCD 52.
• PCD diamond abrasive compact
• the cemented carbide / PCD body is then removed from the reaction capsule using known techniques. As such the cemented carbide / PCD body forms a precursor of a tool insert of the invention.
• the annular region 48 of the substrate 40 is ground or otherwise removed so as to leave a predetermined depth, indicated by the numeral 56, of tungsten carbide material.
• This depth of material 56 is selected so as to correspond to the amount of tungsten carbide material required to mill through the wall of a steel casing or lining of a borehole, as described above.
• the depth of tungsten carbide 56 provides a protective layer for the primary cutting edge 54 of the PCD 52, and also a secondary cutting edge 58 for milling through the steel casing. Once a window has been milled through the steel casing, ideally the layer 56 should be almost expended so as to expose the cutting edge 54 for drilling into the rockbed.
• the tungsten carbide substrate 40 whilst having the desired properties for forming the PCD layer 52, may not have the desired properties for milling through a steel casing or lining.
• the annular protective layer 48 may be replaced by tungsten carbide of a different grade or by another suitable material, such as tool steel, for example.
• the annular region 48 in such a case could be formed as a ring in situ or, alternatively, could be formed as a separate ring component which , is attached to the tool insert.
• the ring 48 may be attached to the tool insert, which has been machined to accept the ring, by for example brazing, press fitting, shrink fitting or any other convenient method.
• a second embodiment of a tool insert of the invention comprises a tungsten carbide substrate 60, a PCD layer 62 having a cutting edge 64, and a tungsten carbide protective overiayer 66 having a cutting edge 68.
• the depth 70 of the protective overiayer 66 is selected so as to mill a window through the steel casing or lining of a borehole in a subterranean bedrock whilst exposing the PCD cutting edge 64 once through the steel casing.
• a third embodiment of a tool insert of the invention is illustrated in figures 5 and 6 of the accompanying drawings.
• the tool insert consists of a cemented carbide substrate 80, a PCD layer 82, having a cutting edge 84, and a tungsten carbide protective segment 86, having a cutting edge 88, bonded to the substrate 80.
• the tungsten carbide segment 86 could be an extension of the substrate 80.
• the tungsten carbide segment 86 could be formed of a tungsten carbide material of a different grade that is adapted to the particular substrate to be milled.
• the depth of the tungsten carbide segment 86 is once again selected so as to protect the cutting edge 84 whilst drilling through a steel casing, but to expose the cutting edge 84 soon after encountering the subterranean bedrock.
• a tungsten carbide substrate 90 includes a number of parallel recesses 92 in which parallel PCD segments or strips 94 are formed.
• the PCD segments 94 are protected by respective tungsten carbide segments or strips 96.
• the cutting edges 98 of respective PCD segments 94 are protected by the tungsten carbide segments 96, which .in turn have cutting edges 100.
• This arrangement allows the tool insert to be used for cutting through successive layers of steel and subterranean bedrock and can therefore be used multiple times.
• a fifth embodiment of a tool insert of the invention comprises a substrate 110 on which is formed a PCD layer 112.
• the substrate 110 and PCD layer 112 would be formed in a conventional high pressure/high temperature apparatus, whereafter the relevant portion of the substrate would be ground away to expose the primary cutting edge 1 14 of the PCD layer 112.
• the substrate 10 and PCD layer 112 are brazed into a cup 116 which is typically formed of a high speed tool steel, which cup 116 includes a cutting edge 118 for milling through the steel casing or lining of a borehole in a subterranean rockbed.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Geology (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Earth Drilling (AREA)
• Processing Of Terminals (AREA)
• Gripping On Spindles (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)
• Processing Of Stones Or Stones Resemblance Materials (AREA)
• Eye Examination Apparatus (AREA)
• Surgical Instruments (AREA)
• Sampling And Sample Adjustment (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 2003
  • 2003-09-12 WO PCT/IB2003/003892 patent/WO2004040095A1/en not_active Ceased
  • 2003-09-12 AT AT03809804T patent/ATE493559T1/de not_active IP Right Cessation
  • 2003-09-12 US US10/533,046 patent/US20060144621A1/en not_active Abandoned
  • 2003-09-12 DE DE60335568T patent/DE60335568D1/de not_active Expired - Lifetime
  • 2003-09-12 AU AU2003259458A patent/AU2003259458A1/en not_active Abandoned
  • 2003-09-12 CN CNB038256371A patent/CN100557188C/zh not_active Expired - Fee Related
  • 2003-09-12 EP EP03809804A patent/EP1565642B1/de not_active Expired - Lifetime
  • 2003-09-12 CA CA2504518A patent/CA2504518C/en not_active Expired - Fee Related
• 2005
  • 2005-05-11 ZA ZA200503785A patent/ZA200503785B/en unknown

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