EP0512154B1 - Centralizer for casings and drill pipes - Google Patents

Centralizer for casings and drill pipes Download PDF

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Publication number
EP0512154B1
EP0512154B1 EP91114238A EP91114238A EP0512154B1 EP 0512154 B1 EP0512154 B1 EP 0512154B1 EP 91114238 A EP91114238 A EP 91114238A EP 91114238 A EP91114238 A EP 91114238A EP 0512154 B1 EP0512154 B1 EP 0512154B1
Authority
EP
European Patent Office
Prior art keywords
grooves
pipes
rings
centralizer
pipe
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
EP91114238A
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German (de)
French (fr)
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EP0512154A1 (en
Inventor
Bernd Reinholdt
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.)
Weatherford Lamb Inc
Original Assignee
Weatherford Oil Tool GmbH
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Filing date
Publication date
Application filed by Weatherford Oil Tool GmbH filed Critical Weatherford Oil Tool GmbH
Publication of EP0512154A1 publication Critical patent/EP0512154A1/en
Application granted granted Critical
Publication of EP0512154B1 publication Critical patent/EP0512154B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/10—Wear protectors; Centralising devices, e.g. stabilisers
    • E21B17/1014—Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well
    • E21B17/1021—Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well with articulated arms or arcuate springs
    • E21B17/1028—Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well with articulated arms or arcuate springs with arcuate springs only, e.g. baskets with outwardly bowed strips for cementing operations

Definitions

  • the invention relates to a centering device for drilling and casing pipes with a centering basket, consisting of two spaced-apart support rings surrounding the pipes to be centered and with spring clips aligned in the longitudinal direction of the pipe, the ends of which are fastened to the support rings.
  • centering baskets are used for the central guidance of pipes, which consist of several spring clips bent outwards and connected to an upper and lower support ring.
  • the centering baskets pushed onto the pipes to be centered provide considerable resistance to pulling them into a borehole or into an enveloping casing due to the outward-facing arches of the spring clips or spring bars, which can only be overcome by high pull-in forces.
  • the pull-in forces should not exceed certain limit values, while the centering forces must reach high values.
  • the centering basket is given the option of being pressed against the outer circumference of the tube by means of clearance for the support rings, so that even small gaps do not constitute an obstacle to being drawn into a borehole, but the tube grooves provided for this purpose are necessarily included a corresponding, undesirable weakening of the pipe cross section.
  • split baskets can be used for the proposed solution.
  • Another alternative according to the utility model provides for the use of stop rings which are welded to the outer circumference of the tube. However, welding on the outer circumference of the pipe is undesirable and additionally involves time-consuming work.
  • the invention has for its object to provide a centering device according to the generic term mentioned, which allows the use of undivided centering baskets, avoids larger, weakening the tube wall thickness grooves, is easy to manufacture and when pulling a tube equipped with centering baskets into a borehole, the spring clip only stressed on train.
  • the solution according to the invention is characterized in that the support rings of the centering baskets have inner circumferential grooves and the pipes to be centered in the region of the support ring grooves are provided with circumferential pipe grooves for receiving stop rings which, after the centering basket has been pushed onto the pipe, through window-like openings in the support rings Pipe circumferential grooves are slidable.
  • the support ring grooves are advantageously designed and arranged in such a way that only tensile forces can act on the spring clips when a pipe string is pulled in and the centering baskets are pressed flat.
  • the centering device according to the invention only requires circumferential grooves with small cross sections to accommodate the stop rings, so that the Weakening of the tube wall thickness is very small. The time required for production is minimal.
  • the springs of the centering baskets are only subjected to tension because the front support ring in the pushing direction comes into contact with its associated stop ring and fixes the centering basket in its position and the opposite support ring carries out compensatory movements can. This avoids upsetting and bulging of the spring clips, which would lead to greater friction and the associated higher pull-in force. Snapping into caverns of the surrounding rock is also avoided.
  • the stop rings in connection with the support rings of the centering baskets withstand extremely high stripping forces.
  • the centering basket shown in FIG. 1 consists of support rings 1 and bow-like leaf springs 2 attached to them.
  • the support rings 1 are provided with inner circumferential grooves 3, in which stop rings 4 engage.
  • the stop rings are arranged in the circumferential pipe grooves 5 of the pipe 6 indicated in broken lines.
  • Each support ring is provided with at least one window-like opening 7, through which the stop rings into the free space can be pushed between the inner groove 3 of the support rings and the circumferential groove 5 of the pipe to be centered.
  • the dimensions provided for the exemplary embodiment according to FIG. 1 are only examples and can be replaced by other dimensions.
  • the assembly process for inserting the stop rings 4 into the space between the support rings 1 and the circumferential groove 5 of a tube to be centered can be seen particularly well in FIG. 1.
  • the stop rings 4 can be seen through the windows in the manner shown, i.e. be inserted almost tangentially. Because of their flexibility, they are able to follow the groove 5 and finally take their seat, as can be seen in the lower area in FIG. 1.
  • the centering cage is then secured against excessive displacement on the pipe. At the same time, its support rings are given freedom of movement within the width of the inner circumferential grooves 3.
  • the groove widths are designed so that the spring clips can be flattened completely by the pulling forces of the pipe string.
  • the front groove side walls 3a in the drawing direction come into contact with the stop rings 4.
  • the rear or inner groove side wall 3b of the support ring rear in the insertion direction approaches the stop ring 4 while maintaining a free space, but without closing it to reach. This ensures that the centering cage gets stuck on the front of the stop rings and that the rear support ring receives enough space until the spring clips are fully extended. This means that only tensile forces can act on the centering cage. The risk of upsetting the spring clips with undesirable bulges is avoided.

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  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
  • Drilling And Boring (AREA)
  • Drilling Tools (AREA)
  • Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)

Abstract

For deep-hole drilling, a centring cage for the central guidance of pipes is proposed in which the supporting rings surrounding the pipes have inner peripheral grooves, and the pipes to be centred are provided in the area of the supporting-ring grooves with stop rings which are arranged in pipe peripheral grooves and can be pushed through window-like openings of the supporting rings into the pipe grooves after the centring cage is pushed onto the pipe. <IMAGE>

Description

Die Erfindung betrifft eine Zentriereinrichtung für Bohr- und Futterrohre mit einem Zentrierkorb , bestehend aus zwei, mit Abstand zueinander angeordneten, die zu zentrierenden Rohre umschließenden Tragringen und mit in Rohrlängsrichtung ausgerichteten Federbügeln, deren Enden an den Tragringen befestigt sind.The invention relates to a centering device for drilling and casing pipes with a centering basket, consisting of two spaced-apart support rings surrounding the pipes to be centered and with spring clips aligned in the longitudinal direction of the pipe, the ends of which are fastened to the support rings.

In der Tiefbohrtechnik sind zur zentralen Führung von Rohren Zentrierkörbe in Gebrauch, die aus mehreren auswärts gebogenen und mit einem oberen und unteren Tragring verbundenen Federbügeln bestehen. Die auf die zu zentrierenden Rohre aufgeschobenen Zentrierkörbe setzen dem Einziehen in ein Bohrloch oder in ein umhüllendes Futterrohr durch die auswärts gerichteten Bögen der Federbügel bzw. Federstäbe erhebliche Widerstände entgegen, die nur durch hohe Einzugskräfte überwunden werden können. Nach vorgegebenen Prüfkriterien sollen dabei die Einzugskräfte bestimmte Grenzwerte nicht überschreiten, die Zentrierkräfte müssen dagegen hohe Werte erreichen. Diese Forderungen sind schwer miteinander zu vereinbaren, da hohe Federkräfte in radialer Richtung Federbügel mit einem stark ausgeprägten Bogen erfordern, so daß gleichzeitig die beim Einziehen zu überwindenden Formwiderstände groß sind. Diese können auch nur dann überwunden werden, wenn zwischen dem Außenumfang des einzuziehenden Rohrstrangs und dem Bohrloch oder einem umgebenden Futterrohr ein genügend freier Ringraum zur Verfügung steht. Ist der Ringspalt jedoch nur klein und beträgt er beispielsweise nur wenige Millimeter, so war es bisher nicht möglich, Zentriervorrichtungen einzusetzen. Deshalb wurde bereits mit einer Zentriervorrichtung nach dem DE-GM 89 03 038 versucht, diese Schwierigkeiten zu beheben. Nach dem bekannten Gebrauchsmuster erhält zwar der Zentrierkorb die Möglichkeit, durch Spielraum für die Tragringe sich bis an den Aussenumfang des Rohres anpressen zu lassen, so daß auch geringe Spalträume kein Hindernis für das Einziehen in ein Bohrloch darstellen, jedoch sind die dafür vorgesehenen Rohrnuten notwendigerweise mit einer entsprechenden, unerwünschten Schwächung des Rohrquerschnitts verbunden. Außerdem können für die vorgesehene Lösung nur Zentrierkörbe in geteilter Ausführung verwendet werden. Eine weitere Alternative nach dem Gebrauchsmuster sieht die Verwendung von Anschlagringen vor, die am Außenumfang des Rohres festgeschweißt werden. Das Schweißen am Rohraußenumfang ist jedoch unerwünscht und zusätzlich mit zeitaufwendiger Arbeit verbunden.In deep drilling technology, centering baskets are used for the central guidance of pipes, which consist of several spring clips bent outwards and connected to an upper and lower support ring. The centering baskets pushed onto the pipes to be centered provide considerable resistance to pulling them into a borehole or into an enveloping casing due to the outward-facing arches of the spring clips or spring bars, which can only be overcome by high pull-in forces. According to specified test criteria, the pull-in forces should not exceed certain limit values, while the centering forces must reach high values. These requirements are difficult to reconcile with each other, since high spring forces in the radial direction require spring clips with a pronounced arc, so that at the same time the form resistances to be overcome when pulling in are large. These can only be overcome if there is sufficient free annular space between the outer circumference of the pipe string to be drawn in and the borehole or a surrounding casing. However, the annular gap is only small and if, for example, it is only a few millimeters, it was previously not possible to use centering devices. Therefore, a centering device according to DE-GM 89 03 038 has already been attempted to remedy these difficulties. According to the known utility model, the centering basket is given the option of being pressed against the outer circumference of the tube by means of clearance for the support rings, so that even small gaps do not constitute an obstacle to being drawn into a borehole, but the tube grooves provided for this purpose are necessarily included a corresponding, undesirable weakening of the pipe cross section. In addition, only split baskets can be used for the proposed solution. Another alternative according to the utility model provides for the use of stop rings which are welded to the outer circumference of the tube. However, welding on the outer circumference of the pipe is undesirable and additionally involves time-consuming work.

Der Erfindung liegt die Aufgabe zu Grunde, eine Zentiereinrichtung nach dem einleitend genannten Gattungsbegriff zu schaffen, welche die Verwendung ungeteilter Zentrierkörbe gestattet, größere, die Rohrwandstärke schwächende Nuten vermeidet, einfach herzustellen ist und beim Einziehen eines mit Zentrierkörben bestückten Rohres in ein Bohrloch die Federbügel nur auf Zug beansprucht. Die erfindungsgemäße Lösung zeichnet sich dadurch aus, daß die Tragringe der Zentrierkörbe innere Umfangsnuten aufweisen und die zu zentrierenden Rohre im Bereich der Tragringnuten mit Rohrumfangsnuten zur Aufnahme von Stoppringen versehen sind, die nach dem Aufschieben des Zentrierkorbs auf das Rohr durch fensterartige Öffnungen der Tragringe in die Rohrumfangsnuten schiebbar sind. Vorteilhafterweise sind die Tragringnuten so gestaltet und angeordnet, daß beim Einziehen eines Rohrstrangs und Flachdrücken der Zentrierkörbe nur Zugkräfte auf die Federbügel wirken können.The invention has for its object to provide a centering device according to the generic term mentioned, which allows the use of undivided centering baskets, avoids larger, weakening the tube wall thickness grooves, is easy to manufacture and when pulling a tube equipped with centering baskets into a borehole, the spring clip only stressed on train. The solution according to the invention is characterized in that the support rings of the centering baskets have inner circumferential grooves and the pipes to be centered in the region of the support ring grooves are provided with circumferential pipe grooves for receiving stop rings which, after the centering basket has been pushed onto the pipe, through window-like openings in the support rings Pipe circumferential grooves are slidable. The support ring grooves are advantageously designed and arranged in such a way that only tensile forces can act on the spring clips when a pipe string is pulled in and the centering baskets are pressed flat.

Die erfindungsgemäße Zentriereinrichtung benötigt nur Rohrumfangsnuten mit kleinen Querschnitten zur Aufnahme der Stoppringe, so daß die Schwächung der Rohrwandstärken sehr gering ist. Der Zeitaufwand für die Herstellung ist nur minimal. Beim Einschub eines mit der erfindungsgemäßen Einrichtung bestückten Rohrstrangs in eine Bohrung geringen Querschnitts werden die Federn der Zentrierkörbe nur auf Zug beansprucht, da der in Schubrichtung vordere Tragring an seinem zugeordneten Stoppring zur Anlage kommt und den Zentrierkorb in seiner Lage fixiert und der gegenüberliegende Tragring Ausgleichsbewegungen ausführen kann. Dadurch wird ein Stauchen und Ausbeulen der Federbügel vermieden, was zu größerer Reibung und damit verbundener höherer Einzugskraft führen würde. Auch das Einrasten in Kavernen des umgebenden Gesteins wird vermieden. Die Stoppringe in Verbindung mit den Tragringen der Zentrierkörbe widerstehen extrem hohen Abstreifkräften.The centering device according to the invention only requires circumferential grooves with small cross sections to accommodate the stop rings, so that the Weakening of the tube wall thickness is very small. The time required for production is minimal. When a pipe string equipped with the device according to the invention is inserted into a bore with a small cross-section, the springs of the centering baskets are only subjected to tension because the front support ring in the pushing direction comes into contact with its associated stop ring and fixes the centering basket in its position and the opposite support ring carries out compensatory movements can. This avoids upsetting and bulging of the spring clips, which would lead to greater friction and the associated higher pull-in force. Snapping into caverns of the surrounding rock is also avoided. The stop rings in connection with the support rings of the centering baskets withstand extremely high stripping forces.

In der Zeichnung ist ein Ausführungsbeispiel der Erfindung schematisch dargestellt und nachstehend erläutert.In the drawing, an embodiment of the invention is shown schematically and explained below.

Es zeigen

Fig. 1
eine schaubildliche Darstellung eines auf ein Rohr aufgeschobenen Zentrierkorbs,
Fig. 2
einen Schnitt durch einen Tragring des Zentrierkorbs in größerem Maßstab und
Fig. 3
einen vergrößerten Ausschnitt aus dem Zentrierkorb gemäß Figur 1, zum Teil im Schnitt.
Show it
Fig. 1
a diagrammatic representation of a centering basket pushed onto a tube,
Fig. 2
a section through a support ring of the centering basket on a larger scale and
Fig. 3
an enlarged section of the centering basket according to Figure 1, partly in section.

Der mit der Figur 1 dargestellte Zentrierkorb besteht aus Tragringen 1 und daran befestigten bügelartigen Blattfedern 2. Die Tragringe 1 sind mit inneren Umfangsnuten 3 versehen, in welche Stoppringe 4 greifen. Die Stoppringe sind in Rohrumfangsnuten 5 des in unterbrochener Strichführung angedeuteten Rohres 6 angeordnet. Jeder Tragring ist mit wenigstens einer fensterartigen Öffnung 7 versehen, durch welche die Stoppringe in den Freiraum zwischen der Innennut 3 der Tragringe und der Umfangsnut 5 des zu zentrierenden Rohres geschoben werden können. Die für das Ausführungsbeispiel gemäß Figur 1 vorgesehenen Maße sind nur beispielhaft und können durch andere Abmessungen ersetzt werden.The centering basket shown in FIG. 1 consists of support rings 1 and bow-like leaf springs 2 attached to them. The support rings 1 are provided with inner circumferential grooves 3, in which stop rings 4 engage. The stop rings are arranged in the circumferential pipe grooves 5 of the pipe 6 indicated in broken lines. Each support ring is provided with at least one window-like opening 7, through which the stop rings into the free space can be pushed between the inner groove 3 of the support rings and the circumferential groove 5 of the pipe to be centered. The dimensions provided for the exemplary embodiment according to FIG. 1 are only examples and can be replaced by other dimensions.

Der Montagevorgang für das Einfügen der Stoppringe 4 in den Zwischenraum zwischen den Tragringen 1 und der Umfangsnut 5 eines zu zentrierenden Rohres ist besonders gut in der Figur 1 erkennbar. Nachdem der Zentrierkorb seinen vorgeschriebenen Sitz nach dem Aufschieben auf das Rohr 6 erreicht hat, d.h. wenn die Umfangsnuten 5 des Rohres durch die Fenster 7 des Zentrierkorbs sichtbar sind, können die Stoppringe 4 durch die Fenster in der dargestellten Weise, d.h. nahezu tangential eingeschoben werden. Aufgrund ihrer Flexibilität sind sie in der Lage, der Nut 5 zu folgen und endgültig ihren Sitz einzunehmen, wie er in der Figur 1 im unteren Bereich erkennbar ist. Der Zentrierkorb ist dann gegen eine zu weite Verschiebung auf dem Rohr gesichert. Gleichzeitig erhalten seine Tragringe eine Bewegungsfreiheit innerhalb der Breite der inneren Umfangsnuten 3. Die Nutbreiten sind so ausgelegt, daß die Federbügel durch Einzugskräfte des Rohrstrangs völlig flachgedrückt werden können. Beim Einziehen eines Rohrstrangs in ein Bohrloch oder in ein Futterrohr gelangen die in Einzugsrichtung vorderen Nutseitenwände 3a zur Anlage an die Stoppringe 4. Die hintere oder innere Nutseitenwand 3b des in Einschubrichtung hinteren Tragrings nähert sich unter Einhaltung eines Freiraums dem Stoppring 4, ohne ihn jedoch zu erreichen. Dadurch ist sichergestellt, daß der Zentrierkorb an dem vorderen der Stoppringe hängenbleibt und der hintere Tragring genügend Freiraum bis zur völligen Streckung der Federbügel erhält. Dadurch können nur Zugkräfte auf den Zentrierkorb wirken. Die Gefahr von Stauchungen der Federbügel mit unerwünschten Ausbeulungen wird vermieden.The assembly process for inserting the stop rings 4 into the space between the support rings 1 and the circumferential groove 5 of a tube to be centered can be seen particularly well in FIG. 1. After the centering basket has reached its prescribed position after being pushed onto the tube 6, i.e. if the circumferential grooves 5 of the tube are visible through the windows 7 of the centering basket, the stop rings 4 can be seen through the windows in the manner shown, i.e. be inserted almost tangentially. Because of their flexibility, they are able to follow the groove 5 and finally take their seat, as can be seen in the lower area in FIG. 1. The centering cage is then secured against excessive displacement on the pipe. At the same time, its support rings are given freedom of movement within the width of the inner circumferential grooves 3. The groove widths are designed so that the spring clips can be flattened completely by the pulling forces of the pipe string. When a pipe string is drawn into a borehole or a casing, the front groove side walls 3a in the drawing direction come into contact with the stop rings 4. The rear or inner groove side wall 3b of the support ring rear in the insertion direction approaches the stop ring 4 while maintaining a free space, but without closing it to reach. This ensures that the centering cage gets stuck on the front of the stop rings and that the rear support ring receives enough space until the spring clips are fully extended. This means that only tensile forces can act on the centering cage. The risk of upsetting the spring clips with undesirable bulges is avoided.

Claims (2)

  1. A centring device for drilling and casing pipes, having a centralizer comprising two spaced-apart supporting rings enclosing the pipes to be centred, and also having spring bows which are aligned in the longitudinal direction of the pipes and whose ends are attached to the supporting rings, characterized in that the supporting rings (1) are provided with internal peripheral grooves (3), and the pipes (6) to be centred are provided in the zone of the grooves in the supporting ring with peripheral pipe grooves (5) for the reception of stop rings (4) which, when the centralizer has been slid onto the pipe, can be slid into the peripheral grooves (5) therein through window-like openings (7) in the supporting rings.
  2. A centring device according to Claim 1, characterized in that the width of the grooves in the supporting ring (3) is larger than the maximum sliding length of the centralizer in the longitudinal direction of the pipes, and the grooves in the supporting ring (3) are so arranged in relation to the radial plane of symmetry of the centralizer that only their outwardly extending lateral faces (3a) act as stop faces for the stop rings (4).
EP91114238A 1991-04-27 1991-08-24 Centralizer for casings and drill pipes Expired - Lifetime EP0512154B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4113898 1991-04-27
DE4113898A DE4113898C2 (en) 1991-04-27 1991-04-27 Centering device for drilling and casing pipes

Publications (2)

Publication Number Publication Date
EP0512154A1 EP0512154A1 (en) 1992-11-11
EP0512154B1 true EP0512154B1 (en) 1995-10-18

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Family Applications (1)

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EP91114238A Expired - Lifetime EP0512154B1 (en) 1991-04-27 1991-08-24 Centralizer for casings and drill pipes

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US (1) US5238062A (en)
EP (1) EP0512154B1 (en)
AT (1) ATE129311T1 (en)
CA (1) CA2067061A1 (en)
DE (2) DE4113898C2 (en)
NO (1) NO304999B1 (en)

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Also Published As

Publication number Publication date
EP0512154A1 (en) 1992-11-11
NO921602L (en) 1992-10-28
DE4113898A1 (en) 1992-10-29
NO921602D0 (en) 1992-04-24
CA2067061A1 (en) 1992-10-28
DE4113898C2 (en) 1994-10-27
DE59106735D1 (en) 1995-11-23
NO304999B1 (en) 1999-03-15
ATE129311T1 (en) 1995-11-15
US5238062A (en) 1993-08-24

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