EP0735232B1 - Outil de coupe pour opérations de forage - Google Patents

Outil de coupe pour opérations de forage Download PDF

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Publication number
EP0735232B1
EP0735232B1 EP19950302012 EP95302012A EP0735232B1 EP 0735232 B1 EP0735232 B1 EP 0735232B1 EP 19950302012 EP19950302012 EP 19950302012 EP 95302012 A EP95302012 A EP 95302012A EP 0735232 B1 EP0735232 B1 EP 0735232B1
Authority
EP
European Patent Office
Prior art keywords
drilling
passage
drilling bit
return passage
nozzle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19950302012
Other languages
German (de)
English (en)
Other versions
EP0735232A1 (fr
Inventor
Clifford Ross Gray
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to EP19950302012 priority Critical patent/EP0735232B1/fr
Priority to DE69519625T priority patent/DE69519625D1/de
Publication of EP0735232A1 publication Critical patent/EP0735232A1/fr
Application granted granted Critical
Publication of EP0735232B1 publication Critical patent/EP0735232B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • E21B10/08—Roller bits
    • E21B10/18—Roller bits characterised by conduits or nozzles for drilling fluids

Definitions

  • This invention relates to drilling bits for use in drilling operations, such as in the oil and gas industry and, in particular, to a bit suitable for alleviating problems associated with running of the drilling bit into a well hole and pulling of the cutter bit from the hole.
  • Conventional drilling bits comprise a generally tubular drilling bit body provided at the bottom end thereof with a plurality of cutters for cutting the well formation.
  • the drilling bit is forged and provided at its bottom end with three legs having attached to their bottom portions, known as shirt tails, mounting pins for securing cone cutter elements made of a durable material.
  • These cutter elements may be conical and are provided with hard cutting teeth, made, for example, from tungsten carbide, for cutting a formation.
  • Through the centre of the drilling bit body is usually provided a bore through which drilling fluids are delivered at high velocity via three conduits to areas adjacent to the cutters to assist in cutting and cuttings removal.
  • the central bore is not itself directly open to the cutting face and, for this reason, a number of problems can arise when a drilling bit is being run into the hole, pulled from the hole or simply being used in cutting operations.
  • the drilling bit body will be in gauge with the walls of the hole and, therefore, as the drilling bit is run into the hole it acts as a piston which compresses material below the bottom end of the drilling bit body.
  • the only relief from the increasing pressures is leakage through zones where the drilling bit body has lesser diameter than the gauge of the hole. However, as these zones only have very small area for flow of cuttings and fluids, the flow is substantially restricted and little pressure relief is obtained.
  • the consequence of such increasing pressures is "surge" or the generation of stresses on the rock formations along the open hole section below the drilling bit. It is known in the oil and gas industry that these stresses or surge pressures cause major damage to weak formations and, more importantly, to productive reservoir sands.
  • the formation may be damaged by fracturing of the formation beneath the cutter bit during running into the hole. This problem is worsened by increasing running speeds and higher viscosity drilling fluids that cause higher pressure drop across the drilling bit. Clearly, damage to the formation, with consequential reductions in oil and gas recovery, is unacceptable to the industry for cost reasons.
  • swabbing a reverse problem known to the industry as "swabbing" occurs.
  • swabbing which results from fluid flow into the reduced pressure area caused by pulling of the drilling bit and drillstring from the hole can cause blowouts which are extremely hazardous.
  • swabbing may result in contamination of the drilling fluids by formation fluids necessitating costly treatment processes and/or increased drilling fluid cost.
  • Swabbing is most pronounced when the drilling bit or drilling stabilisers are encrusted or packed with formation cuttings. In these cases, it becomes increasingly more difficult to maintain an even hydrostatic pressure on both sides of the cutter bit because the already restricted fluid flow area past the outer circumference of the cutter bit is restricted even further.
  • Other factors that contribute to swabbing include variable viscosity drilling fluids and variation in hole diameter.
  • a yet further problem with conventional cutters is poor hole cleaning due to a poor efficiency of cuttings removal from the centre of the cutting area at the bottom of the hole.
  • Conventional drilling bits rely on the delivery of drilling fluid to the bottom of the hole for effective hole cleaning.
  • cleaning from the centre of the hole is much less efficient because cuttings become trapped in recesses between the cutters and the bottom end of the drilling bit body.
  • cutting accumulation in this area can create what is called in the industry bit balling, where the trapped cuttings restrict the rotation of the cutting cones. Bit balling has been a major problem in the industry. Thus the overall cleaning and cutting efficiency of the drilling bit is reduced.
  • the present invention provides a drilling bit comprising:
  • the return passage provides a route for cuttings to escape to the surface of the hole.
  • the return passage exists the body of the drilling bit at an opening which extends in a plane substantially normal to a central axis extending in the same direction as the tubular drill string.
  • the return passage may be found desirable for the return passage to communicate with at least one further passage which by-passes the full diameter portion of the body such that the aforesaid portion at least of the fluid exits from the body through a number of openings.
  • the openings to the further passages need not be located at the same level and can be orientated at a variety of different angles corresponding to the trajectory of the first or further passages which ranges between 0° and 90° to the central axis of the cutter bit body, that is the return passage exits from said body at an opening which extends in a plane having an axis extending at an angle not being perpendicular to the central axis of said body.
  • flow of cutting through the return passage is assisted by jetting drilling fluid through at least one nozzle communicating a drilling fluid supply and the return passage, and having a trajectory the same as the return passage.
  • the drilling bit body may be provided with one or more supply passages communicating a drilling fluid supply with an opening or openings of the cutter bit body located adjacent to the cutting means for supply of drilling fluids, such as cooling and cleaning fluids, thereto.
  • the first passage opening in the bottom portion of the cutter bit body is located in a recess defined by a plurality of cutting means to readily allow transfer of cuttings and fluids from the recess to the second zone of the hole.
  • At least one said nozzle is located at a point adjacent and above the uppermost point of the path of rotation of said cutting means, said nozzle having a trajectory the same as said return passage.
  • a second passage and nozzle communicates a filling fluid supply for the cutter bit with the first passage.
  • at least one said nozzle is located at a point adjacent and above the uppermost point of the path of rotation of said cutting means, said nozzle having a trajectory approximately tangential to the path of rotation of said cutting means.
  • a drilling bit 10 embodying the invention for use in drilling operations comprises a body 10 having a top portion 11 and a bottom portion 12, the bottom portion 12 being provided with cutting means (not shown) for cutting a formation to which the cutter bit is exposed.
  • the drilling bit body 10 above described could be a three cone drilling bit familiar to the drilling industry with the additional provision of the first passage 15.
  • the body 10 is connected to the rest of a drillstring run into the hole by a connecting thread portion 16 provided on the top portion 11 of the body 10.
  • other connecting means may also be used.
  • the body 10 is constructed of a suitable durable material such as steel and the cutting means is comprised, for example, of three rotatable conical cutting elements which are rotatably secured by bearings on pins 30 located on leg members 31 of the drilling bit 1, two of which are shown in Figure 1.
  • the cutting elements may be fabricated from a hard material such as steel or tungsten carbide and be provided with teeth of the same material to provide a cutting action.
  • the cutting elements are rotatable in response to the revolution of the drillstring and lubricated by oil or grease supplied through port 46, one of which is shown in each of Figures 1 to 4.
  • a recess 26 is definable by the cutter elements.
  • cuttings accumulate therein, in the absence of the first passage 15, reducing both the hole cleaning and cutting efficiency of the drilling bit 1.
  • the drilling bit 1 will be an almost solid structure acting as a piston with little pressure relief and increasing the problems of surge and swab. These problems are alleviated to an appreciable extent by provision of the first passage 15. It is also desirable, for the purposes of avoiding plugging of the passage 15 with cuttings, to coat the passage 15 with a non-stick material such as Teflon (Registered Trade Mark).
  • the trajectory of the passage 15 may also be a matter of some importance in practice.
  • the opening 24 through which cuttings and fluids exit the first passage 15 and enter the second zone 21 may be either parallel or perpendicular to a central axis 23 of the central bore 25 of the drilling bit 1.
  • first passage 15 and its opening 24 to the second zone 21 are perpendicular to the central axis 23, erosion of the hole walls may occur, where jetting of drilling fluids is conducted in accordance with the embodiment described with reference to Figure 3. This would be undesirable.
  • the trajectory of the first passage 15 is not critical to the drilling bit in its broadest aspect and it is therefore to be understood that the first passage 15 may be oriented at any angle in the range 0° to 90° to the central axis 23, i.e. not have its axis perpendicular to the central axis of the body 10.
  • the passage opening 24 is parallel to the central axis 23.
  • the first passage 15 is separated by wall 27 from the central bore 25 through which drilling fluids travel via conduit 36 and nozzle 37 to a location adjacent the cutting elements.
  • the flow of drilling fluids passes through the recess 26 and into the first passage 15 thereby enhancing cuttings removal and hole cleaning.
  • the restricted flow area of the conventional drilling bit has been increased by the flow area of the first passage 15 thereby increasing pressure relief and allowing a reduction in surge and swab pressures on running into the hole or pulling from the hole of the drilling bit and drillstring.
  • Figure 2 shows a further embodiment of the invention in which the flow area for communication between the first zone 20 and the second zone 21 of the hole is increased still further by the provision of a plurality of openings, two of which openings 24 and 24a are shown. However, any desired number of openings can be employed. Opening 24a communicates with first passage 15 through a further passage 33.
  • the further passage 33 may likewise be coated with Teflon to improve flow properties and reduce the risk of plugging with cuttings.
  • openings 24 and 24a be at the same level of the drilling bit body 10 or at the same trajectory as each other, though this may be found convenient for the purposes of manufacture and uniform flow distribution.
  • Figure 3 shows a further embodiment of the invention in which the flow of cuttings through first passage 15 is enhanced by jetting of drilling fluids upward through the first passage 15 to create a venturi effect that further assists in cuttings removal from the first zone 20.
  • the conduit 36 communicates through conduit 41 and nozzle 42 with the first passage 15 thereby ensuring flow of drilling fluids into the first passage. Control over jetting velocity can be obtained by suitable sizing of the conduit 41 and nozzle 42.
  • the trajectory of the jet is preferably angularly upward and in the embodiment shown is at 75° to the central axis 23 of the central bore 25 of the drilling bit 1. Although in the embodiment described only one such jet has been provided there could be provided a plurality of such jets to further enhance cuttings removal and hole cleaning.
  • the first passage 15 be designed to avoid erosion damage caused by impingement of high velocity drilling fluids on the walls 15a of the passage. With this end in view, hard facing of a portion of the first passage 15 may be required.
  • Figure 4 shows a still further embodiment of the invention which is identical in many respects to that of Figure 3 described above.
  • the nozzle 37 is absent with conduit 36 being blanked off by blank 47 at the position previously occupied by nozzle 37. Therefore, a jet of higher pressure through conduit 41 and nozzle 42 can be achieved. This facilitates removal of cuttings through the first passage 15 to the surface of the hole.
  • Figure 5 shows a still further embodiment in which conduit 36 extends downwardly a sufficient distance that the nozzle 42 is located to cause a jet of drilling fluid above and adjacent, preferably immediately adjacent, the uppermost point, A, of the path of rotation, B, of each cutter element (not shown).
  • the jet is directed along the trajectory of the first passage 15 to obtain the above described advantages.
  • nozzle 42 is in close proximity to a cutting face to which the drilling bit is exposed.
  • a venturi effect is obtained, creating a suction pressure at the cutting face which greatly assists hole cleaning.

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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)

Claims (8)

  1. Trépan comprenant :
    a)un corps apte à être raccordé à une colonne de forage tubulaire et pivotant autour de son axe, ledit corps présentant une portion de diamètre plein et une portion supérieure comportant au moins un segment circonférentiel qui est positionné radialement vers l'intérieur par rapport à l'axe de la portion de diamètre plein ;
    b)une pluralité de bras s'étendant vers le bas à partir du corps et définissant, entre eux et sous le corps, une zone ;
    c) des moyens de coupe montés sur chaque bras et s'étendant vers l'intérieur, dans la zone, pour couper une formation ; et
    d)un passage de retour traversant le corps vers le haut depuis ladite zone et débouchant au niveau de la portion supérieure à l'opposé du segment circonférentiel, une partie au moins de la boue délivrée depuis la colonne de forage tubulaire vers ladite zone, c'est-à-dire la face de coupe, s'écoulant depuis ladite zone à travers le passage de retour ménagé dans le corps, en dérivation avec la portion de diamètre plein du corps.
  2. Trépan selon la revendication 1, caractérisé en ce que ledit passage de retour débouche dudit corps au niveau d'un orifice qui s'étend dans un plan sensiblement normal à un axe central parallèle à ladite colonne de forage tubulaire.
  3. Trépan selon la revendication 1, caractérisé en ce que ledit passage de retour communique avec au moins un autre passage en dérivation avec la portion de diamètre plein du corps, de telle sorte que cette partie au moins du fluide ressort dudit corps par une pluralité d'orifices.
  4. Trépan selon la revendication 1, caractérisé en ce que ledit passage de retour débouche dudit corps au niveau d'un orifice qui s'étend dans un plan dont un axe forme un angle non perpendiculaire avec un axe central dudit corps
  5. Trépan selon la revendication 1, caractérisé en ce que l'écoulement de déblais à travers ledit passage de retour est assisté par l'injection de boue de forage via au moins une buse qui communique avec une source de boue de forage et le passage de retour et dont la trajectoire est identique à celle du passage de retour.
  6. Trépan selon la revendication 3, caractérisé en ce que l'écoulement de déblais à travers le ou lesdits autres passages est assisté par l'injection de boue de forage via une buse qui communique avec une source de boue de forage et ledit autre passage de retour et dont la trajectoire est identique à celle dudit autre passage.
  7. Trépan selon la revendication 5 ou 6, caractérisé en ce que la ou lesdites buses sont situées à proximité et au-dessus du sommet de la trajectoire de rotation desdits moyens de coupe, la ou lesdites buses ayant une trajectoire identique à celle dudit passage de retour.
  8. Trépan selon la revendication 5 ou 6, caractérisé en ce que ladite ou lesdites buses sont situées à proximité et au-dessus du sommet de la trajectoire de rotation desdits moyens de coupe, ladite buse ayant une trajectoire sensiblement tangentielle à la trajectoire de rotation desdits moyens de coupe.
EP19950302012 1995-03-27 1995-03-27 Outil de coupe pour opérations de forage Expired - Lifetime EP0735232B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19950302012 EP0735232B1 (fr) 1995-03-27 1995-03-27 Outil de coupe pour opérations de forage
DE69519625T DE69519625D1 (de) 1995-03-27 1995-03-27 Bohrmeissel für Bohrvorgänge

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19950302012 EP0735232B1 (fr) 1995-03-27 1995-03-27 Outil de coupe pour opérations de forage

Publications (2)

Publication Number Publication Date
EP0735232A1 EP0735232A1 (fr) 1996-10-02
EP0735232B1 true EP0735232B1 (fr) 2000-12-13

Family

ID=8221146

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19950302012 Expired - Lifetime EP0735232B1 (fr) 1995-03-27 1995-03-27 Outil de coupe pour opérations de forage

Country Status (2)

Country Link
EP (1) EP0735232B1 (fr)
DE (1) DE69519625D1 (fr)

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2692117A (en) * 1951-11-13 1954-10-19 Reed Roller Bit Co Drill bit
US3070182A (en) * 1961-09-21 1962-12-25 John F Runte Self-cleaning fluid circulating drill bit
US3923109A (en) * 1975-02-24 1975-12-02 Jr Edward B Williams Drill tool
US4022285A (en) * 1976-03-11 1977-05-10 Frank Donald D Drill bit with suction and method of dry drilling with liquid column
US4126194A (en) * 1977-07-11 1978-11-21 Smith International, Inc. Rock bit with extended pickup tube
FR2442954A1 (fr) * 1977-11-21 1980-06-27 Inst Francais Du Petrole Outil de forage perfectionne a jet d'aspiration
CA1164855A (fr) * 1980-03-24 1984-04-03 Philip A. Taylor Trepan de foration a mises de coupe sur support tournant
US4372399A (en) * 1982-03-11 1983-02-08 Development Oil Tool Systems Drill bit with wedge shaped eduction jets
US4687067A (en) * 1986-05-01 1987-08-18 Smith International, Inc. Crossflow rotary cone rock bit with extended nozzles

Also Published As

Publication number Publication date
EP0735232A1 (fr) 1996-10-02
DE69519625D1 (de) 2001-01-18

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