EP0605071B1 - Tubing with threaded tubes and a connection sleeve - Google Patents

Description

The invention relates to a pipe string with threaded tubes and a sleeve connecting them according to the preamble of claim 1.

When extracting oil or natural gas or a mixture of both, it is common and known to arrange a turbopump or a turbocompressor at the beginning of a production pipe string if the bearing pressure is too low or to increase the flow rate in the area of the drilling base (EP 0480501). This can be driven hydraulically by means of the supplied liquid or electrically. In the case of a drive by an electric motor, the electrical energy must be supplied to the electric motor via cables. The free cross-section of the delivery pipe is initially obvious for hanging the cable, especially since the axis of the turbomachine is aligned with the axis of the delivery pipe line. Nevertheless, z. B. because of the expected abrasion for safety but also fluidic reasons, the attachment in such a way that the cable is located in the annular space between the concentrically arranged conveyor pipe and casing string. This annulus with the slim-hole bores that are increasingly being designed today anyway narrow, is extremely narrowed in the area of the connecting sleeves, so that a desirable large cable cross section and thus low power losses cannot be achieved. In addition, there is naturally a greatly increased risk of cable damage in the narrowed area of the connections in the event of contacts with or knocking against the inner wall of the casing. Because the depth of the borehole is at least a few hundred meters, usually more than 2000 m, it cannot be ruled out that the cable will get tangled during installation of the pipe string and will be heavily loaded and, in the worst case, can even tear off or the insulation will be damaged.

US-A-4,337,969 discloses a tubular string which can be suspended in a borehole, consisting of individual threaded tubes, the ends of which are alternately formed as a sleeve and as a pin element. This type of connection is called an integral connection. To determine various physical parameters, a measuring device is arranged in the area of the drilling base, which is connected to a measuring cable. The pipe string has a cable protector so that the measuring cable is not damaged when the measuring device is lowered and pulled up. This consists of two arms extending from the outer surface of the tube, which form a channel for the cable to be protected by a distance from one another. To secure the cable, U-shaped clips are inserted through two openings in the tube at certain intervals. The pin element of the respective tube is designed as a rotatable threaded ring and the non-rotatable insertion into one another is carried out by means of a nose which is guided in a groove. To tighten the threaded ring, recesses are provided in the flange area, into which a suitable tool can be inserted.

The object of the invention is to provide a generic pipe string with threaded pipes and a connecting sleeve which connects them and is designed as a separate part, with which large cable cross sections for the electrical drive of a turbopump or a turbocompressor are made possible and an impermissible load on the cable is prevented.

This object is achieved by a sleeve which has at least one groove lying in the longitudinal direction on the outer jacket. The electrical cable is pressed into this groove, fixed and then the pipe string is let down. Since it can not be expected that all the superimposed sleeves of the pipe string after screwing have the same position of the groove with respect to the position of the sleeve below or above it, it is further developed that the outer jacket is arranged three offset by 120 degrees Has grooves. This means that in the worst case the cable is rotated by a maximum of 60 degrees to the preceding sleeve, the bending angle of the cable that is less than 1 ^o can be held. This value can be reduced with the addition of additional grooves, but the effort for the production of the grooves increases and the cross-section of the sleeve is correspondingly weakened. This weakening can be done by a Compensate cross-sectional enlargement, but this is at the expense of the space required for the annular gap between the conveyor pipe and the casing pipe.

wiedergegeben werden, wobei der Ursprung des Polarkoordinatensystems im Mittelpunkt der kreisförmigen Innenkontur der Muffe liegt und Rmax den größten und Rmin den kleinsten Abstand der Außenkontur der Muffe von der Muffenachse darstellt. Daraus ergibt sich, daß jeweils gegenüberliegende Radienwerte sich zu einem konstanten Wert - entsprechend der Summe aus größtem und kleinstem Radius - addieren und daß die aufeinanderfolgenden Radien eines Kreissektors von 60^o sich vom größten bis zum kleinsten Radius ändern und im folgenden 60^o Sektor vom kleinsten zum größten Radius. Diese Radienänderung wiederholt sich bei einem vollen Umfang dreimal. Eine andere Form entspricht einer verkürzten Epizykloide mit drei Zweigen (Bronstein-Semendjajew, 4. Auflage B.G. Teubner Verlagsgesellschaft Leipzig 1961, Kapitel 11, Seiten 88 bis 92). Diese spezielle Epizykloide mit drei Zweigen wird erzeugt durch einen Punkt, der innerhalb eines Kreises liegt, der gleitungsfrei auf der Außenseite eines anderen Kreises rollt, wobei das Verhältnis des Durchmessers vom abrollenden Kreis zum feststehenden Kreis 1:3 beträgt. Damit die Bedingung erfüllt ist, daß jeder Durchmesserschnitt dieser speziellen Querschnittskontur immer den gleichen bzw. annähernd gleichen Durchmesser aufweist, müssen am Übergang eines Zweiges zum nächsten Zweig die aneinanderstoßenden Kurvenabschnitte eine gemeinsame Tangente bilden. Dies kann dadurch erreicht werden, daß der beschreibende Punkt nahe am Mittelpunkt des abrollenden Kreises liegt. Die zuvor beschriebene Querschnittskontur hat den großen Vorteil, daß bei konstantem Durchmesser für jeden Durchmesserschnitt drei Maxima gebildete werden, in denen eine Nut zur Führung des Kabels anordenbar ist. Dadurch wird weniger Platz benötigt im Vergleich zu einer gleich großen kreisrunden Querschnittskontur. Die Anordnung von drei Nuten hat den Vorteil, daß zum einen der Verdrehwinkel für das Kabel maximal 60 Grad zur nächsten Muffe beträgt und im Fall eines Drehstromantriebes gleichzeitig drei Kabel, jeweils für eine der 3 Phasen, geführt abgehängt werden können. Für übliche Kabel mit rundem Querschnitt, wird vorgeschlagen, den Übergang des Nutgrundes in die Seitenwände abzurunden, so daß der Nutgrund einen Halbkreis bildet. Für aus Platzgründen erforderliche Flachkabel kann diese Abrundung oval, elliptisch oder kreisförmig sein. Durch eine solche Abrundung kann sich das Kabel sauber am Nutgrund anschmiegen und auch im Falle von Relativbewegungen zwischen Kabel und Nutgrund wird das Kabel nicht belastet oder beschädigt. Um ein Herausspringen des Kabels aus der Nut zu verhindern, wird außerdem vorgeschlagen, den offenen Bereich durch eine Leiste abzudecken. Diese Leiste kann beispielsweise aus Kunststoff oder Leichtmetall hergestellt werden und weist an den Seiten Stege mit Kontur aus, so daß die Leiste eingeklipst werden kann. Diese Abdeckung hat auch den Vorteil, daß in dem besonders engen Spalt zwischen dem Außenmantel der Muffe und der Innenseite des Futterrohres die Außenseite des Kabels beim Herablassen des Rohrstranges nicht abgerieben oder beschädigt wird.A special cross-sectional outer contour of the sleeve is proposed for extreme conditions with regard to the available gap between the delivery pipe and the casing pipe, in particular in the area of the sleeve of, for example, 7 mm or less, such as are present in the slim-hole bores that are increasingly to be found for economic reasons. The outer contour can be mathematically defined by the circular function $$\text{γ (ϕ) =}\frac{\text{Rmax + Rmin}}{\text{2nd}}\text{+}\frac{\text{Rmax - Rmin}}{\text{2nd}}\text{(sin 3ϕ)}$$

are reproduced, wherein the origin of the polar coordinate system lies in the center of the circular inner contour of the sleeve and Rmax represents the largest and Rmin the smallest distance of the outer contour of the sleeve from the sleeve axis. From this it follows that opposite radii values add up to a constant value - corresponding to the sum of the largest and smallest radius - and that the successive radii of a circular sector of 60 ^o change from the largest to the smallest radius and in the following 60 ^o sector from the smallest to the greatest radius. This change in radius is repeated three times to the full extent. Another form corresponds to a shortened epicycloid with three branches (Bronstein-Semendjajew, 4th edition BG Teubner Verlagsgesellschaft Leipzig 1961, chapter 11, pages 88 to 92). This special three-branch epicycloid is created by a point that lies within a circle that rolls smoothly on the outside of another circle, the ratio of the diameter of the rolling circle to the fixed circle being 1: 3. So that the condition is met that each diameter section of this special cross-sectional contour is always the same or approximately the same Has diameter, the abutting curve sections must form a common tangent at the transition from one branch to the next branch. This can be achieved in that the descriptive point is close to the center of the rolling circle. The cross-sectional contour described above has the great advantage that, with a constant diameter, three maxima are formed for each diameter section, in which a groove for guiding the cable can be arranged. This means that less space is required compared to a circular cross-sectional contour of the same size. The arrangement of three grooves has the advantage that on the one hand the twist angle for the cable is a maximum of 60 degrees to the next sleeve and in the case of a three-phase drive, three cables, each for one of the 3 phases, can be suspended. For conventional cables with a round cross-section, it is proposed to round off the transition of the groove base into the side walls, so that the groove base forms a semicircle. For flat cables required for reasons of space, this rounding can be oval, elliptical or circular. Such a rounding allows the cable to nestle neatly against the base of the groove and, even in the case of relative movements between the cable and the base of the groove, the cable is not stressed or damaged. In order to prevent the cable from jumping out of the groove, it is also proposed to cover the open area with a strip. This bar can be made of plastic or light metal, for example, and has webs with a contour on the sides, so that the bar can be clipped on. This cover also has the advantage that in the particularly narrow gap between the outer jacket of the sleeve and the inside of the casing, the outside of the cable is not rubbed off or damaged when the pipe run is lowered.

The grooves can also be used for a positive transmission of the torque when screwing the connections. Thereby Radial compression in the connection area can be omitted, which can lead to permanent deformations and thus damage to the connection due to the screwing process when using conventional screwing pliers due to the small sleeve wall thicknesses of slim-hole sleeves. The screwing pliers must be equipped with the corresponding jaws and jaw guides.

Figur 1

im Schnitt einen Ausschnitt eines erfindungsgemäßen Rohrstranges

Figur 2

einen hälftigen Querschnitt entlang der Linie A-A in Fig. 3 einer besonderen Ausführungsform

Figur 3

eine Ansicht in Richtung X in Fig. 2

Figur 4

im vergrößerten Maßstab eine abgerundete Nutform

Figur 5

wie Fig. 4, jedoch eine andere Nutform

Figur 6

wie Fig. 5 jedoch mit einer Abdeckung.

The pipe string according to the invention is explained in more detail in the drawing. Show it:

Figure 1

in section a section of a pipe string according to the invention

Figure 2

a half cross-section along the line AA in Fig. 3 of a particular embodiment

Figure 3

a view in the direction X in Fig. 2nd

Figure 4

a rounded groove shape on an enlarged scale

Figure 5

4, but a different groove shape

Figure 6

5, but with a cover.

In Figure 1, a section of a pipe string according to the invention is shown in section. To support the borehole in relation to the mountains 1, a casing pipe 2 is placed, within which the production pipe string is suspended. The detail shown here shows a delivery pipe 3, which is connected by means of a sleeve 4 to the next delivery pipe (not shown here) lying above it. The turbopump 6, which is only sketchily indicated, is arranged in an adapter piece 5, which is connected at one end to the delivery pipe 3. The annular gap between conveyor pipe 3 and casing pipe 2 is sealed with a packer element 7. The suction pipe 8 of the turbopump 6 protrudes into the area of the drilling base 9, the liquid and / or gaseous medium resulting from the slight negative pressure generated by the turbopump 6 Intake pipe 8 flows. In the embodiment shown here, the turbopump 6 is driven by an electric motor that is not visible. The electrical energy is supplied via a cable 11 suspended in the annular gap 10. In the socket area 4, the cable 11 is guided in a groove 12 arranged on the outer jacket. This routing of the cable upwards is continued by the sleeves lying above in the tubing string, which are also provided with a groove. All sleeves preferably have three grooves 12, 12 ', 12'', each offset by 120 degrees. In order to obtain the largest possible overall cable cross section, three cables 11 can be routed simultaneously, ie each in one of the three grooves 12, 12 ', 12''. Especially in the case of three-phase current, the routing of one current phase in a groove 12, 12 ', 12''is advantageous because the respective cable 11 then only requires external insulation and the conductor cross section is not reduced by the additional insulation of the phases which is otherwise required. When three grooves 12, 12 ', 12''are arranged, the twist angle of the cable 11 from the sleeve 4 to the next sleeve is a maximum of 60 degrees.

A special embodiment of a sleeve 13 provided with grooves 12, 12 ′, 12 ″ is shown in a section in FIG. 2 and in a top view in FIG. 3. In the event of an extreme annular gap 10 between the delivery pipe 3 and the casing pipe 2, in particular in the area of the sleeve 4, a sleeve 13 with a cross-sectional contour 14 shown in FIG. 3 is used. This cross-sectional contour 14 corresponds geometrically to a shortened epicycloid with three branches. This contour 14 has three maxima in which the grooves 12, 12 ', 12''are arranged. In the transition area between one branch 15 and the next branch 15 ', the two abutting curve sections 16, 16' have a common tangent. This ensures that the diameter is always the same for each diameter section.

The section shown in Figure 2 along the line A-A in Fig. 3 shows that in this embodiment the sleeve thread 17 is conical and the sleeve 13 in the unthreaded section 18 has a butt shoulder 19 with a 15 degree inclination. It is easy to see that for the inventive routing of an electrical cable 11 by means of the grooves 12, 12 ', 12' 'arranged on the outer jacket, the type of execution of the thread is irrelevant. For example, the sleeve could have a cylindrical thread. The degree of bulging of the maximum depends on the diameter of the cable 11 to be guided, since after the grooves 12, 12 ', 12' 'have been made, sufficient wall material must still remain for the sleeve 13. Because of the notch effect of grooves 12, 12 ', 12' ', it is advantageous to round off the transition from groove base 20 to the side walls.

Variants of roundings are shown in FIGS. 4 and 5 on an enlarged scale. The cable 11, 11 'shown in dashed lines shows that the conformity is better compared to a rectangular groove 12.

Figure 6 also shows on an enlarged scale the cover of the open area of a groove 24. This cover consists of a strip 21 which have webs 22 with contours on the sides, so that the strip can be clipped on. This prevents the cable 11 from being abraded or damaged on the inner wall 23 of the casing 2 when the tubing string is installed.

Claims (7)

1. A pipe line with threaded pipes (3) and a bushing (4) connecting them which is designed as a separate part, which is suspended in a bore hole for conveying a liquid and/or gaseous medium, with an electrically driven pump (6) or compressor being arranged at the beginning of the pipe line in the region of the bottom of the bore hole (9) and the electric motor being supplied with electric power via a cable (11) suspended in the bore hole, wherein the respective bushings (4) of the pipe line have on the outer casing three grooves (12, 12', 12") each offset by 120° and located in the longitudinal direction, in which bores the cable (11, 11') or the cables is or are guided.
2. A pipe line according to Claim 1, characterised in that the cross-sectional contour of the outer casing corresponds to a shortened epicycloid with three branches and the groove (12, 12', 12") is arranged in the respective maximum region of the cross-sectional contour.
3. A pipe line according to Claim 1, characterised in that the cross-sectional contour of the outer casing corresponds to the circular function $$\text{r(ϕ) =}\frac{\text{Rmax + Rmin}}{\text{2}}\text{+}\frac{\text{Rmax - Rmin}}{\text{2}}\text{(sin 3 ϕ)}$$

   

   wherein

   Rmax = maximum distance from the outer contour to the bushing axis

   Rmin = minimum distance from the outer contour to the bushing axis

   ϕ = angle of revolution

   and in each case opposing radius values add up to a constant value, corresponding to the total of maximum and minimum radius, and the radius changes from maximum to minimum value repeat three times during one complete rotation and in which the groove (12, 12', 12") is located in the respective maximum region of the cross-sectional contour.
4. A pipe line according to Claim 2 or 3,
   characterised in that the diameter is of identical or approximately identical size for each diameter section.
5. A pipe line according to one of the preceding claims, characterised in that the groove base (20) merges into the side walls in rounded manner.
6. A pipe line according to Claims 1 to 5,
   characterised in that in each case a cable (11, 11') with a three-phase current phase is guided in a groove (12, 12', 12").
7. A pipe line according to Claims 1 to 5,
   characterised in that the open region of the groove (24) is covered by a clip-in strip (21).

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