US3516488A - Device for introducing tools or instruments into an underwater well from a floating installation - Google Patents

Description

June 23, 1970 P. JOUBERT ETAL 3,516,488

DEVICE FOR INTRODUCING TOOLS OR INSTRUMENTS INTO AN NDERWATER WELL FROM A FLOATING INSTALLATION Filed Dec. 26, 7 2 Sheets-Sheet l PHILIPPE T BERT and ANDRE CASTELA Wa M June 23, 1970 JOUBERT ETAL 3,516,488

DEVICE FOR INTRODUCING TOOLS 0R INSTRUMENTS INTO AN UNDERWATER WELL FROM A FLOATING INSTALLATION Filed D60. 26, 1967 2 Sheets-Sheet 2 PHILIPPE TQUBERT and AN CASTELA m F; I QM ATTORNEY S United States Patent 3,516,488 DEVICE FOR INTRODUCING TOOLS 0R INSTRU- MENTS INTO AN UNDERWATER WELL FROM A FLOATING INSTALLATION Philippe Joubert, Rungis, and Andr Castela, Mesnil-Le- Roi, France, assignors to Institut Francais du Petrole, des Carburants et Lubrifiants, Rueil-Malmaison, France Filed Dec. 26, 1967, Ser. No. 693,584 Claims priority, applicatiozrgsFrance, Dec. 28, 1%6,

Int. Cl. E21b 337035; E21c 19/00 US. Cl. 166-5 7 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a device which permits the introduction of servicing tools or measuring instiuments into an underwater well provided with a submerged well-head, from a floating installation, by suspending these tools or instruments by a flexible line connected with the floating installation.

Prior to the present invention, there did not exist any device or apparatus permitting the performances of such an operation directly from a floating installation and it was necessary for the operators to dive down to the level of the well-head in order to place the servicing apparatus into position and make it work.

For working over well-heads located at depths which are inaccessible to divers, only attempts were made with submersibles provided with manipulating arms controlled either from the interior of the submersible or from the water surface, or also remotely controlled servicing devices provided with a lock for introducing tools into the well, whereby the whole apparatus is laid onto the top of the well and must be raised each time the tool has to be changed.

A first object of the invention is to provide a device of the above-mentioned type which is easy to use and capable of operating directly from a floating installation such as a ship, without requiring the use of an upwardly directed tubular extension of the well-head, known in the art as a riser.

Moreover, the adaptation of such a tubular extension to a producing oil well having a submerged well-head, in order to introduce thereinto servicing tools or measuring instruments, comes up against problems concerning the design of the connections of the tubular element with the well-head and with the floating installation, since these connections must both have a suflicient resistance against the high pressure within the well and adapt themselves to the unavoidable movements of the floating installation.

This problem is solved, according to the invention, with ice a servicing device for a submerged oil Well provided with a well-head, for introducing into said well tools suspended by a flexible line from a mobile surface installation. This device includes a flexible pipe for guiding .the lowering of said tools, said pipe connecting the wellhead with the surface installation and being provided at its lower part with means for connecting said pipe with the top of the well-head, means for permanently keeping under tension said pipe between the well-head and the surface installation and two rigid bell-mouthed guiding devices surrounding said pipe at respective locations respectively close to the well-head and to the surface installation, said guiding devices limiting the inclination which may be taken by said flexible pipe at said locations. These guiding devices consist of a downwardly widened upper guiding device carried by the surface installation and an upwardly widened lower guiding device adapted to the top of said connecting means, the internal wall of said guiding device having in a section by an axial plane on incured profile whose slope, with respect to the guiding device axis, has a continuous variation.

; The flexible pipe of the device according to the invention can be easily stored on the floating installation, rapidly handled and easily connected with the well-head by sliding along guide cables connecting the floating installation with the well-head.

An embodiment of the invention will be hereinafter described, by way of example only, with reference to the attached drawings wherein:

FIG. 1 illustrates an overall view of the device according to the invention,

FIG. 1a diagrammatically illustrates an embodiment of the flexible pipe.

FIGS. 2 and 3 show two different embodiments of the guarding devices of this device.

In FIG. 1, the reference numeral 1 designates elements such as a servicing tool (for example a tool for scraping the tubings of a well) or a measuring instrument which is intended to be introduced into a submerged oil well.

These elements are introduced into the well through the well-head 2, from a floating installation 3 which is kept in position substantially above the well, by means of any suitable anchoring or positioning system. The elements 1 are lowered at the lower part of a handling cable 4 which is held in a point 5 on the floating installation, as by a winch, whose rotation is controllable and which may be locked, to maintain the element 1 in a substantially stationary position.

The servicing device according to the invention includes a flexible pipe 6, whose lower end is provided with a connector 7 for its connection with the top of 'the well-head. Means are provided for locking this connector on the well-head, these locking means being remotely controllable through a line 8a of the control cable or hose 8 connected with a control station 9 on the floating installation.

The control cable 8 may consist of several lines, such as lines 8a, 8b and as shown in FIG. 1A, so as to permit, in particular, the control from the station 9 of the opening or closing of the valves of the well-head 2, such as master valve 31 and top valve 32 through lines 8b and 8c of control cable 8 when the connector is connected with the latter, particularly when the element 1 is to be introduced into the well. The valve system (master 3 valves 31 and top valves 32) adapted to the well-head may be of a conventional type and have therefore not been discribed.

The different lines 8a, 8b and 8c of the control cable 8 may be embedded in the tubular core of pipe 6, as diagrammatically illustrated in FIG. 1A.

The connector 7 is surmounted by a blow out preventer 13, which may be of a known type, adapted to withstand the pressure of the fluid inside the oil well-head.

The connection of the connector 7 with the top of the well-head may be performed in a known manner, using guiding elements such as the element 10, adapted to guide this connector during the lowering thereof at the lower part of the pipe 6, by sliding along guide cables 11 and 12 connecting the well-head with the floating installation.

At the upper end of the pipe 6 may be adapted a lock which a lock of a known type may be adapted to permit elements to be introduced into the well, such as the element 1, suspended by a cable which axially traverses the lock and is slidable therethrough for the lowering of the elements.

This lock is moreover not indispensable and may be substituted for by a simple stufling box 27 located at the upper part of a tube 26 and is adapted to the upper end of the pipe 6. The cable is slidable through this stufling box which provides for hydraulic tightness and is associated with an outlet pipe 28 for the outlet of the excess of fluid under pressure in the pipe 6 after the remotely controlled closing of the well-head valves and/or of the blow out preventer 13.

Rigid elements having the shape of incurved funnels with small angles of aperture are adapted to the upper end of the pipe (element 24) and to its lower end (element 25), so maintain a sufficiently high radius of curvature of the flexible pipe to permit the introduction into the pipe (element 24) and into the well-head (element 25) of the servicing elements 1 of usual types lowered by means of the handling cable 4.

The replacement of the element 1 or the withdrawal thereof is effected after this element has been raised above the level of the connecting point 17 of the cable 16 and after the well-head valves and/or the blow out preventer 13 have been closed and the excess of pressure within the pipe 6 has been eliminated through the outlet pipe 28 and/or after closing the blow out preventer 29 which may optionally be adapted to the lower end of the tube 26.

The tube 26 or the lock located at this level will advantageously be detachable so as to make easier the operations of connecting the element 1 with the end of the cable 4 and of withdrawing this element.

A device which allows the element 1 suspended by a cable 4 to be maintained, in an absolutely stationary position within the well, irrespective to the vertical movements (due to the waves, tides, etc.) which the floating installation is subjected to, includes a frame 14 which is vertically movable along a guiding track or slide 15 and a cable flexible line 16 having a connecting point at the upper part of the pipe 6 and a holding point 18 on the floating installation.

The frame 14 carries a first return pulley 19 for the cable 16 and a second return pulley 20 for the cable 4 by which the element 1 is suspended. The return pulley 20 is movable with respect to the floating installation since this pulley is carried by the frame 14.

This frame is subjected to the action of means for permanently keeping under tension the cable 16 and the flexible pipe 6, this means being constituted in the illustrated embodiment by an hydraulic jack or ram 21 connected through the pipe 22 with a source of hydraulic fluid (not shown), such as an oleo-pneumatic accumulator.

Under these conditions, the distance between the point 17 and the well-head remains constant in spite of the displacements of the floating installation. The position on the floating installation of the holding point 18 for the cable 16 is so selected that the portion 16a of this cable is perpendicular to the plane of the water-line of the floating installation, i.e. is substantially vertical.

The cable 4 which supports the element 1 passes between the pulley 20 and the holding point 5 (winch on which the cable is reeled) on a supplementary return pulley 23 the axis of which is integral with the floating installation.

The position 01 tnls pulley 23 on the floating installation is so selected that the cable 4 between the pulleys 20 and 23 runs in a direction which is substantially perpendicular to the plane of the water-line of the floating installation.

When the rotation of the winch 5 is blocked, this arrangement keeps the element 1 at a fixed level inside the well.

Assuming that the floating installation 3 is vertically moved by the waves over a height h, in either direction, with respect to the water bottom; the frame 14 moves in the same direction by 11/2 With respect to the water bottom, since the cable 16 and the flexible pipe 6 are kept under tension between a connecting point 17, located at a constant distance from the water bottom, and a holding point 18 which is integral with the floating installation and thus displaced by h.

A displacement 11/2 results therefrom with respect to the water bottom of the return pulley 20 carried by the frame 14 and On which the cable 4 passes and the pulley 23 integral with the floating installation is simultaneously displaced by h, with respect to the water bottom.

Consequently the distance between the element 1, and the water bottom remains unchanged, since the portion 4a of the cable 4 is parallel to the direction of displacement and the length of the portion 4b of the cable 4 is invariable as long as the length of the cable 4 unreeled by the winch 5 is unchanged.

The same process of automatic adjustment of the position of the pulleys 19 and 20 permits the servicing element to be maintained at a substantially constant distance of the well-head when the floating installation is subjected to horizontal displacements of low amplitude.

These displacements cause an inclination of the flexible pipe 6 and hence a variation in the level of its end 17 which, as a result of the constant length of the cable 16, results in a displacement of the pulley 19 and of the frame 14 over a distance which is substantially equal to one half of the variation in the level of the end 17 with respect to the floating installation.

The guiding devices 24, 25 according to the invention, two embodiments of which being shown by way of nonlimitative examples by FIGS. 2 and 3, limit the radius of curvature taken by the flexible pipe 6, near the Water surface and the water bottom respectively under the action of the water currents and of the unavoidable movements of the floating installation. This radius of curvature is limited to a value which is compatible both with the bending-resistance of the pipe 6 and with the necessity to provide for a sufficient clearance between the internal wall of the pipe 6 and the extremities of each tool or instrument 1 lowered into the well, or more precisely the extremities of each rigid element of this tool or instrument (the most commonly used tools being constituted by several elements linked to each other), so as to avoid the jamming of these tools or elements inside the flexible pipe, in the vicinity of the water bottom or of the water surface.

The guiding devices used according to the invention have a bell-mouthed shape differing substantially from the conical shape which could lead to the break of the pipe at the level of the vertex of the cone, as a result of the brutal variation at this level in the slope of the retaining surface which would be provided for the flexible pipe by a conical guiding device.

According to the invention, the internal wall of each guiding device 24 and 25a has in section by an axial plane an incurved profile with a very progressive variation in the slope of this profile with respect to the guiding device axis, when the distance of this wall to said axis decreases.

In order to make quite impossible any jamming of the tools or instruments 1 at the level of the guiding devices, the radius of curvature R of the internal wall of these guiding devices will be at any point greater than the value R given by the formula:

R L2 2 d2) mm. d)

wherein D is the internal diameter of the flexible pipe 6, d the maximal diameter of the tools introduced into the well through this pipe and 2L the length of the rigid part of the tool (length between two swivel-joints in the case of a conventional tool consituted by a succession of elements (la, lb, 10 linked to each other (FIG. 2).

With the types of flexible pipes and servicing tools available at the present time, the value of R will generally be between 5 and 20 metres, these values not, however, being limitative.

For example, for an inner diameter of the flexible pipe 6 equal to 70 mm., the passage of an element having a length of 2 metres without any swivel-joint requires a minimal radius of curvature of the internal wall of the guiding devices equal to 13 metres.

It will be possible for example, for the ease of fabrication, as in the embodiment shown by FIG. 2, to use guiding devices the internal walls of which have in a section by an axial plane a profile with a constant radius of curvature R (profile of an arc of a circle).

The height h of the guiding device is limited on grounds of weight and overall dimensions.

The angle of inclination of the pipe 6 with respect to the axis of the guiding device at the level of the widened rim thereof must be limited, by a suflicient traction on the pipe, to a value at least equal to the angle oz complying with the relation R sin u=h, at being the inclination at this level of the tangent to the curve internally limiting this guiding device in a section by an axial plane.

The tractive force acting on the pipe 6 is exerted by the hydraulic jack 21 and depends in particular of the characteristics of the pipe 6, of the strength of the underwater currents and of the ratio 6/H, 6 being the maximal amplitude of the horizontal displacements of the installation with respect to the vertical of the well and H the water depth.

The 'tractive force to be exerted on the pipe 6 will generally be of the order of a few tons to some tens of tons and it will be necessary to admit angles of inclination of a few degrees for the pipe 6 in the vicinity of the water bottom and of the water surface respectively.

The angle of inclination of the pipe at the surface has a smaller value than that in the vicinity of the water bottom, as a result of the action of the weight of this pipe (or more exactly of its apparent weight in the water).

In FIG. 2, the tension applied to the pipe 6 is indicated by the reference T.

According to an advantageous embodiment of the guiding devices, shown by FIG. 3, the widened rim of the guiding device is extended by an incurved flange 30 having a radius of curvature smaller than the value R i.e. insufficient for allowing the passage of the tools within the pipe *6 if the latter is applied against this flange as a result, for example, of a casual horizontal displacement of great amplitude of the floating surface installation. The value of the radius of curvature of the wall of this flange 30 is however at least equal to the minimal radius for winding the pipe 6 (and for example equal to the radius of the winch on which this pipe is reeled on the floating surface installation) thus providing for the pipe 6 a retaining surface which prevents this pipe from breaking.

What is claimed is:

1. Device for working over a submerged well provided with a well-head, for introducing into said well tools suspended by a flexible line from a mobile surface installa tion, said device including a flexible pipe for guiding said tools during the lowering thereof, said pipe connecting said well-head with said surface installation, and being provided at its lower end with means for connecting said pipe with said well-head, means for permanently keeping under tension said pipe between said well-head and said surface installation and two guiding bell-mounted devices surrounding said flexibe pipe at locations respectively close to said well-head and to said surface installation, said devices limiting the inclinations taken by the pipe at said locations, said guiding devices comprising a downwardly widening upper guiding device carried by said surface installation, and an upwardly widening lower guiding device adapted to the top of said connecting means, the internal wall of said guiding devices having in a section by an axial plane an incurved profile the slope of which, relative to the guiding device axis, has a continuous variation.

2. Device according to claim 1, wherein the widened rim of the lower guiding device is provided with a safety flange whose wall which may come into contact with said pipe has a radius of curvature smaller than the radius of the adjacent internal wall of said guiding device at the level of the widened flange thereof, but at least equal to the minimal radius necessary for reeling said flexible pipe.

3. Device for working over a submerged well provided with a well-head, for introducing into said well tools suspended by a flexible line from a mobile surface installation, said device including a flexible pipe for guiding said tools during the lowering thereof, said pipe connecting said well-head with said surface installation, and being provided at its lower end with means for connecting said pipe with said well-head, means for permanently keeping under tension said pipe between said well-head and said surface installation and two guiding bell-mouthed devices surrounding said flexible pipe at locations respectively close to said well-head and to said surface installation, said devices limiting the inclinations taken by the pipe at said locations, said guiding devices comprising a downwardly widening upper guiding device carried by said surface installation, an upwardly widening lower guiding device adapted to the top of said connecting means, the internal wall of said guiding devices having in a section by an axial plane an incurved profile the slope of which, relative to the guiding device axis, has a continuous variation and having in each point a radius of curvature greater than D being the internal diameter of the flexible pipe, d the maximal diameter of the tools to be introduced into the well through said pipe and L half the length of the rigid part of said tools.

4. Device for working over a submerged oil well provided with a production well-head which includes a system of valves, for introducing into said well tools suspended by a flexible line from a mobile surface installation, said device including a flexible pipe for guiding said tools during the lowering thereof, said pipe connecting said well-head with said surface installation, and being provided at its lower end with means for connecting said pipe with said well-head, means for permanently keeping under tension said pipe between said well-head and said surface installation and two guiding bell-mouthed devices surrounding said flexible pipe at locations respectively close to said well-head and to said surface installation, said devices limiting the inclinations taken by the pipe at said locations, said guiding devices comprising a downwardly widening upper guiding device carried by said surface installation, and an upwardly widening lower guiding device adapted to the top of said connecting means, the internal wall of said guiding devices having in a section by an axial plane an incurved profile the slope of which, relative to the guiding device axis, has a continuous variation, said flexible pipe being adapted to withstand the pressure inside said Well and including at its lower part a connector which is connected to the surface installation by a line for remote control and provides both for the hydraulic connection with the well-head and for the connection of the wellhead valves with said remote control line, said line being provided with a blow-out preventer at one of its ends and being provided at its upper part with means for introducing said tools into said flexible pipe, said means being provided at their upper part with sealing means allowing the free sliding of said flexible line by which said tool is suspended.

5. Device according to claim 4, wherein said flexible pipe is provided at its lower part with a blowout preventer connected With said surface installation by a line for remote control.

6. Device according to claim 4, wherein conductors for remote control are incorporated in said flexible pipe.

7. Device according to claim 4, wherein a blowout preventer is located at the upper part of said flexible pipe, at a level which is lower than that of said sealing means.

References Cited UNITED STATES PATENTS 3,142,343 7/1964 Otteman et al 1757 3,142,344 7/1964 Otteman et a1. 175-7 3,276,746 10/1966 Berne l-5 X 3,277,969 10/1966 Vincent l755 3,336,975 8/1967 Word 166.5 3,367,421 2/1968 Raulins 166.5 3,378,067 4/1968 Leonard et a1. 166-.5

NILE C. BYERS, JR., Primary Examiner R. E. FAVREAU, Assistant Examiner U.S. Cl. X.R. -7

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