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Dokumentenidentifikation EP0424452 28.04.1994
EP-Veröffentlichungsnummer 0424452
Titel STOPFEN FÜR BOHRLOCHMESSUNGEN.
Anmelder Phoenix Petroleum Services Ltd., Inverurie, Schottland/Scotland, GB
Erfinder SCHNEIDER, John, L., Skene Aberdeenshire AB3 6YF, GB;
BARCIA, Hugo, Miguel, West Hill Aberdeen AB3 6SF, GB
Vertreter derzeit kein Vertreter bestellt
DE-Aktenzeichen 68914157
Vertragsstaaten DE, FR, GB, IT, NL
Sprache des Dokument En
EP-Anmeldetag 13.07.1989
EP-Aktenzeichen 899084628
WO-Anmeldetag 13.07.1989
PCT-Aktenzeichen GB8900799
WO-Veröffentlichungsnummer 9000667
WO-Veröffentlichungsdatum 25.01.1990
EP-Offenlegungsdatum 02.05.1991
EP date of grant 23.03.1994
Veröffentlichungstag im Patentblatt 28.04.1994
IPC-Hauptklasse E21B 33/10
IPC-Nebenklasse E21B 23/00   E21B 47/06   

Beschreibung[en]

This invention relates to logging plugs for use in oil, gas and other wells.

To ascertain parameters of well operations such as pressure, temperature and flow rate one or more logging tools are run down the well on a logging or slick line cable, which will subsequently be referred to by the further alternative term wireline. As many of these parameters must be measured while the pressure in the perforation zone is different from that obtaining in the upper part of the well down which the logging tool is run, it is necessary for the wireline to be passed through a logging plug which maintains a good, but not perfect seal, with the wire, and which is itself sealable within a nipple incorporated in production tubing, by-pass tubing or the well casing.

Considerations arising from a typical employment of a conventional logging plug will now be discussed with reference to the accompanying diagrammatic drawings in which:

  • Figure 1 is a vertical section through a length of an oil well including a perforated zone, and a logging plug, electric submersible pump (ESP) and by-pass system installed therein with the pump running;
  • Figure 2 corresponds to Fig. 1 and shows pressures obtaining after the pump has been switched off;
  • Figure 3 corresponds to Figs. 1 and 2 illustrates a stage in the removal of the logging plug; and
  • Figure 4 is a detail illustrating circulation in the absence of a logging plug.

As shown in Fig. 1 a well casing 10 has a perforated zone 12 through which oil flows from a reservoir 14 as indicated by the arrows 16. From the bottom of a production string 18 is suspended a Y-crossover tool 20 from which depends an electric submersible pump 22 with the interposition of a pump sub 24 containing a non-return valve 26. From the tool 20 there also depends a length of by-pass tubing 28 formed with a nipple 30 in which a conventional logging plug 32 is sealed; slidably passing through the plug 32 but in effective sealing engagement therewith is a wireline 34 from which a logging tool 36 for measuring well parameters is suspended.

In Fig. 1 the pressure obtaining within the well casing is denoted P&sub2; and the pressure on the outlet side of the pump 22 which is higher than P&sub2;, as P&sub1;. There is thus a differential pressure P&sub1;-P&sub2;, defined as ΔP&sub1;, acting downwardly on the logging plug 32. As this differential pressure holds the plug firmly in place, it must be substantially eliminated to allow the logging plug to be removed, and the tools withdrawn. However, equalisation of pressure cannot be achieved simply by switching off the pump 22 due to the action of the non-return valve 26, as will now be explained with reference to Fig. 2.

When the pump 22 is switched off the pressure below the check valve 26 will increase until it equals the static reservoir pressure P&sub3;. P&sub3; is greater than running pump intake (flowing well bore) pressure P&sub2; but less than pump discharge pressure P&sub1; which still obtains above check valve 26. The pressure differential holding the plug 32 in place will now be P&sub1;-P&sub3;, defined as ΔP&sub2;, and the force exerted on the plug 32 will be ΔP&sub2; x (cross-sectional area of plug 32).

In current practice the pressure differential is equalised simply by relying on leakage past the wireline 34, as indicted by the arrows 38 in Fig. 3, where there is not, as previously mentioned, a perfect seal. However, it can take considerable time for such equalisation to occur, and P&sub1; to equal P&sub3;, thus allowing the logging plug 32 to be withdrawn, withdrawal being effected by abutment with the tool 36 as shown in Fig. 3.

Fig. 4 illustrates the situation if it were attempted to run a logging tool through a by-pass system without isolation. As before the intake pressure of pump 22 is designated P&sub2; and the discharge pressure P&sub1;, the pressure differential P&sub1;-P&sub2; being defined as ΔP. The existence of this differential tends to cause re-circulation of pumped fluid around the by-pass system in the direction of the arrows 40.

A logging plug may be used in other situations in which it is required to suspend a logging tool on a wireline passing through a point of pressure differential, for example in a standard well completion without an ESP being present in the well.

US-A-3 180 420 discloses a retrievable bridging plug which may be locked in a well casing simply to form a seal against flow in either direction. Removal of the plug is effected by pulling a sleeve upwards, initial movement of the sleeve relatively to a central stem uncovering ports in the stem which communicate with a blind central bore therethrough. Flow passages through the bridging plug are thus established which facilitate the withdrawal of the plug through well fluid, after it has been unlocked by continued upward pull on the sleeve.

The present invention allows for the first time the use of logging tools in wells with electric submersible pump by-pass completions, giving to the well operator additional information which was previously unavailable.

US-A-4 307 783 discloses a piece of surface equipment which allows well logging operations to be carried out in potential blow-out conditions, and is essentially a lock which allows the logging tool to be removed. The equipment of US-A-4 307 783 is designed to contain pressure from below, whereas the plug of the present invention can be released even though it is being forced downwards by the action of differential pressure. Moreover, this prior art equipment cannot be lowered into the well, as can the logging plug of the present invention, to a predetermined position in order to isolate the production tubing below the plug from the production tubing above the plug, whilst allowing logging operations to be carried out below the plug.

It is an aim of the present invention to provide a logging plug which allows the pressures obtaining above and below the plug to rapidly equalise and thus allow withdrawal of the plug and logging tools.

According to the present invention there is provided a plug for sealing a well bore or tubing string, comprising a hollow body provided with sealing means by which it may be sealed within a nipple included in the well bore or tubing string, and an equalising member arranged for sliding movement relatively to the body between a sealing portion in which a path for fluid flow from above said body across the sealing means to below said body is closed and an open position in which said flow is allowed, characterised in that the plug is a logging plug in which the hollow body and equalising member are apertured to allow a logging tool to be suspended at any desired position below the plug, the hollow body providing or receiving flow tube means to maintain a substantial seal across the plug.

Preferably the equalising member has at least one port communicating with an axial bore through which the wireline passes and which in the sealing position is closed by a sleeve forming part of the hollow body, and in the flow position communicates with one or more ports formed through the wall of the hollow body.

Preferably again, the equalising member is located at the lower end of the logging tool so that it may be displaced from the first to the second position by the upward impact of a logging hammer or of a logging tool attached to the wireline.

An embodiment of the invention will now be described, by way of example, with reference to Figure 5 of the accompanying drawings which is an axial section through an equalising logging plug according to the invention.

The equalising logging plug 50 shown in Fig. 5 surrounds the wireline 34 and comprises a hollow body 52 fitted at its lower end with seals 54 by which it may be seated in a nipple, for example the nipple 30 of Fig. 1. Ports 56 are formed in the wall of the body 52 above the packers 54.

Sealed within the upper part of the body 52 by an O-ring 58 and retained by a collar 60 is a flow tube 62 having an internal diameter such that the wireline 34 may pass freely therethrough in the presence or absence of a pressure differential without causing substantial friction or wear, but on the other hand allowing very little fluid flow around the wireline 34.

Forming the lower part of the body 52 is an insert 64 having an axial bore 65, the upper portion 65a and the reduced diameter medial portion 65b of which receive in a close sliding fit lengths of an equalising tube 66 which itself has an axial bore of a diameter such as to define with the wireline 34 passing there-through an annular passage 68. The tube 66 is sealed within the bore portion 65a by O-ring 70, and within the bore through the body 52 in which its upper part is a sliding fit by O-ring 72. Lateral communication through the wall of the tube 66 with the annular passage 68 is provided by upper ports 74 and lower ports 76. A snap ring 78 is recessed into the equalising tube 66 in a position which in the Fig. 5 condition is just below the bore portion 65b.

A logging hammer 80 may be secured to the wireline 34 above or below the plug 50 to assist in either seating the logging plug in the nipple or removing it from the nipple.

If the plug 50 is substituted, in the by-bass system operating shown in Fig. 1, for the plug 32, well fluid discharged from the pump 22 will similarly be pumped through the Y-crossover tool 20 and production string 18, but a negligible quantity will flow between the flow tube 62 and wireline 34 and through the annular passage 68 to be recirculated through the pump 22; a seal with the wireline 34 is thus established in the by-pass tubing 28 while still allowing passage of the wireline 34.

When the plug 50 is in the closed condition shown in Fig. 5 there is no communication from the ports 56 through the body 52 down across the seal 54 to the bottom of plug 50: as will be seen the O-ring 70 blocks communication through the bore 65, and the O-ring 72 through the bore in the body 52, blocking leakage into the annular passage 68 round the top of the tube 66. The plug 50 thus effectively seals across the nipple 30.

As explained in connection with Fig. 3 the plug is still subjected to a considerable downward force ( ΔP&sub2; x cross-sectional area) after the pump 22 has been switched off. It is usually operationally impossible to pull the logging plug 32 out of the nipple 30 by applying a upward force greater than this downward force, and it is therefore necessary to equalise the pressure differential from above to below the plug. Such equalisation is readily achieved with the plug 50.

It will be noted that by virtue of the annular passage 68 the pressure on the tube 66 is the same at all points. No pressure differential therefore has to be overcome in displacing the tube 66 upwards, which can easily be achieved by pulling on the wireline 34 and striking the bottom of the tube 66 with logging hammer 80 or the logging tool. The consequent upward displacement of the tube 66 to a position in which the ports 74 are in register with the ports 56 establishes fluid communication from above the seals 54, through the ports 56 and 74 and the annular passage 68, and out into the by-pass tubing 28 below the packers 54 via both the lower ports 76 and the open end of the annular passage 68. The upward displacement of the tube 66 compresses the snap ring 78 as it passes through the bore portion 65b; after the ring 78 passes the shoulder at the top of bore portion 65b it expands to maintain the tube 66 in its upper, open position.

After fluid flow through the lower part of the plug 50 along the above-described route has achieved equalisation of the pressures above and below the packers 54, the plug 50 may easily be withdrawn from the nipple 30 and the well.

Instead of the snap ring 78 a similar retaining device such as a shear pin may be used.


Anspruch[de]
  1. Stopfen zum Abdichten eines Bohrlochs oder einer Fördertour, der einen Hohlkörper (52) umfasst, der mit einem Abdichtungsmittel (54) versehen ist, durch das er in einem in dem Bohrloch oder der Fördertour eingeschlossenen Verbindungsstück abgedichtet werden kann, und ein Ausgleichsglied (66), das zur Gleitbewegung relativ zu dem Körper (52) zwischen einem Abdichtungsteil, in dem ein Weg für Flüssigkeitsströmung von über dem Körper (52) entlang des Abdichtungsmittels (54) bis unter den Körper (52) geschlossen ist, und einer offenen Stellung, in der Strömung gestattet ist, angeordnet ist, dadurch gekennzeichnet, dass der Stopfen ein Bohrlochmessungsstopfen (50) ist, in dem der Hohlkörper (52) und ein Ausgleichsglied (66) Öffnungen haben, um zu gestatten, dass ein Bohrlochmessungswerkzeug in jeder gewünschten Stellung unter dem Stopfen (50) aufgehängt werden kann, wobei der Hohlkörper (52) ein Strömungsrohrmittel (62) liefert oder empfängt, um eine wesentliche Abdichtung über dem Stopfen beizubehalten.
  2. Bohrlochmessungsstopfen (50) nach Anspruch 1, in dem das Ausgleichsglied (66) eine Axialbohrung (68) hat, die mit wenigstens einer Öffnung (74) in Verbindung steht, die in der Abdichtungsstellung durch den Hohlkörper (52) geschlossen ist, und in der Strömungsstellung mit einer oder mehreren durch die Wand des Hohlkörpers (52) gebildeten Öffnungen (56) in Verbindung steht.
  3. Bohrlochmessungsstopfen (50) nach Anspruch 2, in dem das Ausgleichsglied (66) wenigstens eine weitere Öffnung (76) hat, die mit der Axialbohrung (68) an dem von der einen Öffnung (56) entfernten Ende in Verbindung steht, und die in der Abdichtungsstellung ausserhalb des Hohlkörpers (52) liegt, und in der Strömungsstellung mit einem ringförmigen Raum (65) in Verbindung steht, der von dem Ausgleichsglied (66) und dem äusseren Ende des Hohlkörpers (52) definiert wird.
  4. Bohrlochmessungsstopfen (50) nach Anspruch 1, 2 oder 3, in dem das Ausgleichsglied (66) in dem unteren Ende des Bohrlochmessungsstopfens (50) angeordnet ist, so dass es von der Abdichtungs- zur Strömungsstellung durch nach oben gerichteten Stoss eines Bohrlochmessungshammers (80) oder eines Bohrlochmessungswerkzeugs verschoben werden kann.
  5. Bohrlochmessungsstopfen (50) nach einem der vorhergehenden Ansprüche, und der zusätzlich ein Rückhaltemittel (78) umfasst, um das Ausgleichsglied in der Strömungsstellung beizubehalten.
  6. Bohrlochmessungsstopfen (50) nach einem der vorhergehenden Ansprüche, wenn er in einem Bohrloch in Verbindung mit einem Bohrlochmessungshammer (80) angebracht ist, der über oder unter dem Stopfen (50) angeordnet ist.
Anspruch[en]
  1. A plug for sealing a well bore or tubing string, comprising a hollow body (52) provided with sealing means (54) by which it may be sealed within a nipple included in the well bore or tubing string, and an equalising member (66) arranged for sliding movement relatively to the body (52) between a sealing portion in which a path for fluid flow from above said body (52) across the sealing means (54) to below said body (52) is closed and an open position in which said flow is allowed, characterised in that the plug is a logging plug (50) in which the hollow body (52) and equalising member (66) are apertured to allow a logging tool to be suspended at any desired position below the plug (50), the hollow body (52) providing or receiving flow tube means (62) to maintain a substantial seal across the plug (50).
  2. A logging plug (50) as claimed in claim 1, in which the equalising member (66) has an axial bore (68) communicating with at least one port (74) which in the sealing position is closed by the hollow body (52), and in the flow position communicates with one or more ports (56) formed through the wall of the hollow body (52).
  3. A logging plug (50) as claimed in claim 2, in which the equalising member (66) has at least one further port (76) communicating with said axial bore (68) at the end thereof remote from said one port (56) and which in said sealing position is outside the hollow body (52) and in said flow position communicates with an annular space (65) defined by the equalising member (66) and the outer end of said hollow body (52).
  4. A logging plug (50) as claimed in claim 1, 2 or 3, in which the equalising member (66) is located at the lower end of the logging plug (50) so that it may be displaced from the sealing to the flow position by the upward impact of a logging hammer (80) or of a logging tool.
  5. A logging plug (50) as claimed in any preceding claim, and additionally comprising retaining means (78) to maintain the equalising member (66) in said flow position.
  6. A logging plug (50) as claimed in any preceding claim when positioned in a well in conjunction with a logging hammer (80) arranged above or below the plug (50).
Anspruch[fr]
  1. Bouchon pour obturer un forage de puits ou une rame de tubes, comportant un corps creux (52) ayant un moyen d'étanchéité (54) au moyen duquel l'étanchéité est assurée dans un manchon fileté prévu dans le forage du puits ou la rame de tubes, et un élément compensateur (66) disposé pour coulisser par rapport au corps creux (52) entre une zone d'étanchéification en laquelle le chemin du débit de fluide depuis ledit corps creux (52) traversant le moyen d'étanchéité (54) jusqu'au niveau inférieur audit corps creux (52) est fermé et une position ouverte permettant ledit débit, caractérisé en ce que le bouchon est un bouchon diagraphe (50) dans lequel le corps creux (52) et l'élément compensateur (66) sont percés pour permettre d'y suspendre un outil diagraphe en toute position recherchée sous le bouchon (50), le corps creux 52 prévoyant ou admettant un moyen à tube de débit (62) pour maintenir une étanchéité importante en travers du bouchon (50).
  2. Bouchon diagraphe (50) selon la revendication 1, dont l'élément compensateur (66) prévoit un alésage axial (68) communiquant avec un orifice (74) au minimum lequel en position de mode étanchéité est fermé par le corps creux (52) et en position de mode débit communique avec un ou plusieurs orifices (56) formés dans le trou du corps creux (52).
  3. Bouchon diagraphe (50) selon la revendication 2, dont l'élément compensateur (66) prévoit au minimum un alésage supplémentaire (76) communiquant avec ledit alésage axial (68) à l'autre extrémité par rapport audit orifice (56), et lequel en ledit mode étanchéité est à l'extérieur du corps creux (52) et en ledit mode débit communique avec un vide annulaire (65) défini par l'élément compensateur (66) et l'extrémité extérieure dudit corps creux (52).
  4. Bouchon diagraphe (50) selon la revendication 1, 2 ou 3, dont l'élément compensateur (66) est situé à l'extrémité inférieure du bouchon diagraphe (50) de telle façon à permettre son déplacement du mode étanchéité en mode débit par l'impact remontant d'un pilon diagraphe (80) ou d'un outil diagraphe.
  5. Bouchon diagraphe (50) selon l'une ou l'autre des revendications précédentes, comportant en outre des moyens de retenue (78) pour maintenir l'élément compensateur (66) en ledit mode débit.
  6. Bouchon diagraphe (50) selon l'une ou l'autre des revendications précédentes installé dans un forage en conjonction avec un pilon diagraphe (80) disposé au dessus ou en dessous du bouchon (50).






IPC
A Täglicher Lebensbedarf
B Arbeitsverfahren; Transportieren
C Chemie; Hüttenwesen
D Textilien; Papier
E Bauwesen; Erdbohren; Bergbau
F Maschinenbau; Beleuchtung; Heizung; Waffen; Sprengen
G Physik
H Elektrotechnik

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