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
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/10—Sealing or packing boreholes or wells in the borehole
  • E21B33/12—Packers; Plugs
  • E21B33/126—Packers; Plugs with fluid-pressure-operated elastic cup or skirt
• • 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
  • E21B10/38—Percussion drill bits characterised by conduits or nozzles for drilling fluids
• • 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
  • E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
  • E21B21/12—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor using drilling pipes with plural fluid passages, e.g. closed circulation systems
• • 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
  • E21B7/20—Driving or forcing casings or pipes into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes

Definitions

• the present invention relates to a drilling device, in particular by use of a down-the-hole hammer, and a drilling method in particular for overburden drilling.
• Drilling devices denoted “down-the-hole hammer” have a rotating percussion drilling head which is lowered into the borehole.
• Other terms used therefor are "Inhole-hammer” and “DTH-hammer” , which term will be used in the following.
• overburden drilling is intended to denote a drilling method wherein a tube providing a casing for the borehole is dragged along at least in the region of the bottom of the borehole.
• the known device further has a skirt open at its lower end in the area of the hammer, through which the compressed air enriched with the cuttings is fed to the distributor.
• the drilling device has a DTH-hammer with a percussion drill bit, a drilling tube with a waste conduit for the cuttings and at least one supply conduit for the flushing medium, and an overburden tube connected to the drill bit.
• a ring is mounted preferably rotatably around the drill pipe, on which ring at least one, preferably two to five disks are arranged as a seal.
• rubber disks separated by smaller diameter plastic disks are used, where an outer diameter of the rubber disks corresponds to, i.e. is about equal to or slightly larger than, an inner diameter of the overburden tube.
• the tile of rubber and plastic disks is preferably held together by two steel disks of a lesser diameter, which are screwed together.
• the seal assembly of the disks and a ring supporting same is preferably secured by a flange or the like.
• the invention provides a method of overburden drilling using air lifting.
• the method according to the invention comprises supplying the flushing medium, in particular peripherally to the carrying away of the cuttings, at least over a predominant part of the drilling depth, and dragging along an overburden tube adjacent the surrounding rock.
• the overburden tube does not rotate, or rotates more slowly relative to the surrounding rock than a centrally arranged drill pipe for the supply and carrying away of the flushing medium.
• the method according to the invention further comprises the sealing of the borehole bottom against the borehole opening, and in particular the dragging along of the sealing packing.
• the packing rotates relatively to the surrounding rock at most with the speed of the drill pipe, and at least with the speed of the overburden tube.
• a rotative-percussive drilling method which comprises the supplying of energy by means of an energy transfer medium to a hammer arranged in the borehole concurrently with rotating the hammer.
• a drilling device according to the invention has a reduced free cross-section around the hammer at most ten times as large as the free cross-sectional area within the waste conduit .
• Figure 1 a drilling device according to the invention in a lengthwise sectional view
• Figure 2 a drilling device according to the invention in cross-sectional view
• Figure 3 a plug as used with the invention in cross-sectional view
• Figure 4 a sketch overview of a drilling device according to the invention
• Figure 5 another drilling device according to the invention in a partial lengthwise sectional view.
• the drill rig 1 comprises a drill pipe 2 with a central waste conduit 3 and a peripherally arranged air supply conduit 4.
• a connecting piece 5 is welded, in which a DTH-drill head 6 is screwed with its central connector 7, which comprises a compressed air supply opening 8 through which the DTH-drill head 6 is supplied with compressed air for driving its percussion drill bit 9.
• the diameter of the drill bit 9 is larger than the diameter of the drill pipe 2 and is larger than the diameter of the drive part of the DTH-drill head 6.
• a supply conduit section 10 leads from the centrally arranged waste conduit 3 of the drill pipe 2 obliquely downwards to a laterally arranged inlet opening 11.
• An air duct section 13 leads from the peripheral air conduit 4 of the drill pipe 2 via a connection annulus 111 to a central area of the connector 7 of the drill head.
• the percussion drill bit 9 is driven with compressed air, which in the example is provided by a compressor station 60 located adjacent the borehole opening, to perform a hammering action while being rotated by the drill rig 1.
• the drill bit 9 includes a central pilot bit 9a and a surrounding reaming bit 9b.
• the pilot bit 9a and the reaming bit 9b are connected to one another by a releasable bayonet coupling.
• the reaming bit 9b is rotatably, and preferably coaxially, connected to an overburden tube 12 via a casing shoe 15, thereby dragging along the overburden tube 12 during drilling.
• the air flowing from the borehole bottom back to the borehole opening serves as a flushing medium and maintains a flow velocity in the central waste conduit 3 sufficient to carry away the cuttings.
• the flow velocity exceeds 30 m/s, and is preferably 70-80 m/s, in particular about 75 m/s.
• the drill bit 9 further comprises a supply duct section 41 for compressed air 42 flowing from the hammer 6 into the drill bit 9, a supply duct 43, a waste duct 44, a bypass (choke shunt) 45 and a waste discharge duct 46 for compressed air 47 flowing back towards the surface.
• a supply duct section 41 for compressed air 42 flowing from the hammer 6 into the drill bit 9 a supply duct 43, a waste duct 44, a bypass (choke shunt) 45 and a waste discharge duct 46 for compressed air 47 flowing back towards the surface.
• drill elements 50a and 50b of the pilot and reaming bit, respectively are arranged.
• the reaming bit 9b is, on the one hand, releasably reconnected to the pilot bit 9a via the securing elements 51, 52, 53, and on the other hand is rotatably connected to the casing shoe 15, so that the reaming bit 9b is able to drag along the casing shoe 15 as well as the overburden tube 12 welded thereto.
• the overburden tube 12 does not rotate, or rotates much more slowly relative to the surrounding rock than the drill bit 9, depending on the friction provided by the borehole wall and the torque applied through the drill bit 9.
• Compressors 60 having a combined throughput capacity of 30 to 80 m 3 /min, preferably 50 to 70 m 3 /min, serve as the compressed air supply for an 18 "-DTH-hammer and a drill pipe having 200 mm outer tube diameter and 125 mm inner tube diameter. With increasing drilling depth and grain size of the cuttings, accordingly larger air supply rates are used. Also, the supply rates scale with hole diameter.
• a plug 18 ( Figure 3) is set as a sealing packing which tightly fits between the overburden tube 12 and the drill pipe 2 and is carried downwards during drilling along with the drill pipe 2.
• the plug 18 in the embodiment shown comprises three resilient disks 20 supported in a spaced apart manner by two rigid disks 22 of a lesser diameter. Two to four or five rubber disks are preferred, spaced apart by a number of plastic disks one less. The pile of rubber disks and plastic disks is held on both sides by steel disks 24 of the same diameter as the plastic disks 22, and six threaded bolts 28 passing through bores 26 in the disks, and nuts.
• the stack of disks is arranged on a mounting ring 30 and fastened with bolts 32 accessible through a flange hole 31, whereby the mounting ring 30 is rotatably mounted on the drill pipe 2 and is fixed in axial direction by a fixing ring 34 welded to the drill pipe 2.
• the mounting ring 30 does not rotate with the drill pipe 2, or possibly rotates slowly, while the rubber disks 20 contact the inner wall of the overburden tube 12.
• the sealing disks of the plug 18 rotate with a speed of at least that of the overburden tube and less than that of the drill pipe 2.
• an inflatable tube ring (packer”) is arranged on the mounting ring 30.
• no overburden tube is present, and the rubber disks accordingly seal against the borehole wall .
• overburden tube 18 for example a pipe of dimensions 711 (28")x8 mm is used, into the inner diameter of which of 695 mm, the rubber disks 20 of the plug are fit.
• the rubber, steel and plastic disks of the plug 18 each have a thickness of 15 mm.
• These disks are mounted on a bronze ring 30 as shown in Figure 3, the bronze ring 30 in turn being rotatably sled onto the drill pipe 2 of outer diameter 200 mm, and secured in axial direction by a fixing ring 34.
• a drill collar 36 (see Figure 4) is arranged for damping the upward hammer action and for thereby directing hammer action downwardly.
• the drill collar 36 is, for example, formed as a part of the drill pipe 2 with an outer sleeve filled with lead.
• the plug 18 is arranged above or preferably, below the drill collar 36.
• the overburden tube is a contiguous pipe string, which is continuously appended during drilling and may be left in the borehole after drilling.
• the overburden tube is not appended beyond the plug, but is closed at its upper end by a e.g. frustoconical lid piece.
• the lid piece is formed as a sealing packing, so that the plug is dispensible.
• the lid piece rotatably seals against the drill pipe.
• a sleeve tube 14 surrounding the hammer 6 is arranged below the lateral inlet opening 41, wherein the sleeve tube is closed below the inlet opening 41, preferably at its lower end, and preferably is double-walled.
• the sleeve tube 14 extends upwardly somewhat beyond the inlet opening 41, namely up to the upper rim of the connector 5, wherein a duct 115 is formed in the sleeve tube 14 for the lateral inlet opening 11.
• the flushing medium is forced to flow through the constricted annular space (outer shaded area in Figure 2) between the sleeve tube 14 and the overburden tube 12. Due to the constricted free cross section, the flow speed at the height of the hammer 6 is increased so as to secure the blowing out of the cuttings.
• the drill bit 9 is rotated, while an energy transfer medium, e.g. a portion of the flushing medium, is supplied through the drill pipe 2 to the hammer 6 for transmitting a percussive action onto the rotating drill bit 9.
• an energy transfer medium e.g. a portion of the flushing medium
• an overburden tube 12 and a sealing packing 18 between the overburden tube 12 and the drill pipe 2 is dragged, and the cuttings are flushed away through the drill pipe 2.
• the overburden tube may be continuously supplemented at its upper end at the borehole opening, or may the closed at its top after mounting the seal. In the former case, the overburden tube may be left in the borehole after conclusion of the drilling, or may be taken out of the hole. In the latter case, there is the advantage that the frictional resistance provided by the dragged-along overburden tube remains independent of the drill depth, and therefore does not set a substantial limit thereto.
• the drilling methods of the invention have the advantage that by carrying along the plug 18 above the air distributing connector
• the flow-through cross-section for the cuttings is constricted in the area of the hammer, if necessary by means of a sleeve tube surrounding the hammer, in such a manner that the cross-section is at most 10 times as large as the inner cross-section of the waste conduit of the drill pipe (inner shaded area in Figure 2) , on the other hand preferably not less than same, in particular is at least four times as large, and particularly preferably is six to eight times as large, such that even coarse cuttings can pass through.
• the necessary constriction may also be achieved by using an oversized hammer, which is preferably choked below its nominal operation pressure (e.g. ⁇ 6.9 bar) so as not to damage the drill bit due to its nominally excessive energy output.
• the cross-sectional shape of the constricting device may be other than cylindrical, e.g. may have an undulating circumference providing a number of alternating more and less constricted portions, respectively.
• the overburden tube, the waste conduit of the drill pipe and the optional sleeve tube circular- cylindrically, in particular concentrically.
• the three lengths see Figure 2):
• the optional sleeve tube is preferably single or dual walled and may comprise a duct or a cut-out connecting the inlet opening of the distributor with the annular space surrounding the sleeve tube. Further, the sleeve tube may extend at its upper end up to the drill pipe or the distributor, and at its lower end down to the lower end of the hammer. Preferably, the lower end of the device or tube is closed, but it suffices if the closure is located below the distributor inlet.
• the drilling method is carried out in a first section, at a relatively larger hole diameter, using such a sleeve tube; and after reaching a certain depth of the borehole, a second section is drilled with a smaller hole diameter without the sleeve tube, or with a smaller diameter sleeve tube.
• a detention casing Into the upper, wider hole section, there can e.g. be installed a detention casing. In this manner, the entire drilling operation can be accomplished with largely the same components and with accordingly reduced requirements in terms of space, time and cost.

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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)

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• 2005
  • 2005-06-10 DE DE502005001190T patent/DE502005001190D1/de active Active
  • 2005-06-10 AT AT05012538T patent/ATE369481T1/de active
  • 2005-06-10 EP EP05012538A patent/EP1731708B1/de active Active
• 2006
  • 2006-06-07 CN CNA2006800204977A patent/CN101203656A/zh active Pending
  • 2006-06-07 EP EP06743121A patent/EP1907663B1/de active Active
  • 2006-06-07 CA CA002654785A patent/CA2654785A1/en not_active Abandoned
  • 2006-06-07 US US11/921,904 patent/US20090101413A1/en not_active Abandoned
  • 2006-06-07 AU AU2006256971A patent/AU2006256971A1/en not_active Abandoned
  • 2006-06-07 WO PCT/EP2006/005427 patent/WO2006131339A1/en active Application Filing
  • 2006-06-07 AP AP2007004293A patent/AP2007004293A0/xx unknown
  • 2006-06-07 ZA ZA200800106A patent/ZA200800106B/xx unknown
  • 2006-06-07 EA EA200800001A patent/EA014437B1/ru not_active IP Right Cessation

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