EP1360392A1

EP1360392A1 - Safety valve for oil wells

Info

Publication number: EP1360392A1
Application number: EP02711970A
Authority: EP
Inventors: Jean-Robert Sangla
Original assignee: IFP Energies Nouvelles IFPEN; Pyreneenne de Metallurgie Ste
Current assignee: IFP Energies Nouvelles IFPEN; Pyreneenne de Metallurgie Ste
Priority date: 2001-02-02
Filing date: 2002-01-16
Publication date: 2003-11-12
Anticipated expiration: 2022-01-16
Also published as: US7040409B2; ATE368796T1; FR2820457A1; WO2002063129A1; DE60221499D1; FR2820457B1; US20040045722A1; EP1360392B1

Abstract

The invention relates to a safety valve for wells installed in a production tubing, comprising a body (17) having means for plugging (18) a passage inside the body, means for anchoring (19) the body in the tubing and means for sealing (20) between the body and the wall of the tubing. The inventive valve comprises means for communicating (14) a hydraulic pressure between the valve and the surface of the wells. According to the invention, the plugging, anchoring and sealing means comprise hydraulic activation means such that the hydraulic pressure transmitted from the surface activates the means in such a way as to open the passage, anchor the valve in the tubing and activate the sealing means on the wall of the tubing.

Description

SAFETY VALVE FOR OIL WELLS

The present invention relates to a method for securing a

oil well with or without a faulty bottom safety valve.

We know that, for safety reasons, oil wells are

generally fitted with bottom safety valves which are either interposed

between the connection of two tube elements, either inserted into a receptacle

housed in the production tube of the well a few tens or hundreds of

meters deep. The function of these valves is to stop

automatically produce effluent if an incident occurs at the head of

well or downstream from them. They are often ordered from the surface

by hydraulic pressure on opening and close automatically at

by means of a powerful return spring as soon as a fall in the

hydraulic pressure on the control line, whether this drop is

ordered or accidental.

Hydraulic control line may also have faults

(leak, blocked or broken line), the safety valve can no longer play

his role. It generally remains closed under the action of its spring and blocks the passage of the effluent. Two solutions are currently available to the operator to overcome this

deficiency. He can extract the safety valve from the production tube (after setting up an airlock at the wellhead) and then close the control line

defective by installing an insulation jacket in the production tube fitted with gaskets which isolate the arrival of the

control through the receptacle. The well can produce again but it

then finds outside safety standards since it is no longer equipped with a

bottom safety valve. Another solution avoiding this extraordinary operation consists in "killing" the well, that is to say balancing the pressure of the

deposit with a hydrostatic column of mud of adequate density, then in

intervening in the well to repair according to the techniques of the profession.

This solution, which then makes it possible to work according to security standards, is

extremely heavy and expensive.

Document FR-2734863 discloses a method and a device

allowing to restore the safety of the well by installing, according to the rules of

loom, a special safety valve. However, the technique according to this

document requires reassembly of the defective bottom valve and the

reuse of its receptacle to set up the special valve. Thus, this method imposes a precise dimension to which the new valve is fixed,

given the reuse of the receptacle for its locking system and its tightness. The present invention relates to a well safety valve

comprising improvements with respect to the special valve and the

tools as described in the document already cited FR-2734863. The current

valve according to the invention can be placed directly in space

inside a production tube of known inside diameter, without requiring

adapted receptacle. There is no longer any need to adjust the length of the

connecting rods between the valve and the surface wellhead.

Thus, the present invention relates to a well safety valve

placement in a production tube, comprising a body comprising

means for closing off an internal passage to the body, anchoring means

of the body in the tube, sealing means between the body and the wall of the

tube, the valve comprising means for communicating a pressure

between the valve and the surface of the well. According to the invention, the means

closure, anchoring and sealing include activation means

hydraulic such as the hydraulic pressure transmitted from the active surface the

means so as to open said passage, anchor the valve in the tube and activate

the sealing means on the wall of the tube.

The closure means may include a valve maintained in

closed position by a return means, a hydraulic piston providing

presses a longitudinal displacement of a shirt so as to maintain

open the valve. The anchoring means may include jaws which can be

moved radially against the wall of the tube by an anchor jacket

a hydraulic piston.

The anchor can be mechanically locked by means

immobilization of the anchor jacket.

The sealing means may comprise a stack of several

annular seals made of resilient material which can be compressed by the

displacement of a compression sleeve of a hydraulic piston.

The section of the annular seals can be in the form of a V whose

length of the branches is asymmetrical, the branch in internal contact with

the valve body being the shortest, the branch in contact with the wall of the

tube, after compression of the stack by the piston, is deformed to enter

in contact with the wall of the tube.

The stack can include a metal anti-extrusion cup,

the outside diameter is approximately the outside diameter of the valve body

before compression of the stack.

The stack can consist of eight V-shaped elastomer cups

HNBR type of shore hardness A about 80.

The stack can be mechanically kept compressed by

means for immobilizing the compression liner.

The hydraulic communication means can be constituted by

tubular elements joined together by fittings, one end a first element is connected to the body of said valve, one end of the upper element is connected to a suspension element.

The suspension element can be held in an adapter fixed on

the well head and comprising hydraulic communication means with

said tubular elements.

The adapter may include jaws with radial displacement

intended to be clamped on said tubular elements.

The invention also relates to a method of positioning the

valve according to the invention in a production tube, in which one performs

the following steps:

- an adapter is assembled on the well head,

- the valve is lowered into the production tube by assembling a

number of tubular elements corresponding to the desired dimension,

- the valve and its tubular elements are suspended on the adapter via a suspension head, and the hydraulic pipe is connected

said tubular elements to a surface pressure source,

- the valve is pressurized to open the passage, anchor the body

the valve in the tube at the level where it is located, compress the stack of seals

to make the annular seal.

Depending on the method, the well can be made safe by dropping

the pressure in the valve to close said passage closure means without unlocking the anchor or deactivating the stacking of the seals

annular.

The tubular elements can be disconnected and reassembled before lowering a tool adapted to connect to the head of the valve body and to

unlocking the anchors and the compression means by threshing

stacking.

The present invention will be better understood and its advantages

will appear more clearly on reading the description of the examples

following, in no way limiting, illustrated by the attached figures below,

among which: FIGS. 1A and 1B schematically show a valve according to the prior art,

FIGS. 2A and 2B schematically show an installation comprising a valve according to the present invention,

FIG. 3 shows in longitudinal section an embodiment of a valve according to the invention,

FIGS. 4A and 4B schematically show the principle of all of the sealing and anchoring means of the valve according to the invention.

FIG. 1A shows an oil well 1 equipped with a bottom safety valve 2, the hydraulic control line 3 of which is defective. Well comprises a production tube 4 (tubing) in communication with a shaft of

christmas 5. This safety valve is positioned in a receptacle 6 (nipple).

To repair and bring the well back into conformity, the valve must be removed from its

headquarters to install a new valve that will restore production

in the shortest possible time, and in complete safety. In case the line of

control can no longer be operational, a valve can be installed

safety in the seat or receptacle 6, valve as described in the document

FR-2734863, cited here with reference.

Figure 1B shows this valve consisting of three main

sets:

the shutter assembly 7, or valve proper, controlled by

hydraulic pressure,

- the set of adaptation and connection flanges 8,

- and all of the lines 9 connecting this “adapter” 8 and the valve 7.

The details of this equipment and the installation procedures or

of operations are clearly described in the document cited above. Account

given the length fixed between the receptacle and the position of the element

adapter 8, the number of rods 9 and their total length must be

determined according to the well in question.

FIG. 2A shows a well 11 comprising a production tube 10

of known internal diameter. In case it is necessary to add a

safety valve inside this tube, one can advantageously use the system according to the invention, shown diagrammatically in FIG. 2B. A

adapter 12 is interposed between the master valves 13 and the suspension of the

tubing hanger. This device is similar to that described

in document FR-2734863 in that it has at least two functions:

suspension of the control rods 14 using the lower lateral screws 50,

and sealing around the suspension head 21 so as to communicate with

an external hydraulic control line 15. But according to this

variant, the adapter 12 also has two jaws 51a and 51b allowing

the operation of the valve and rod elements in the tubing. So the

suspension and hanging of the rods is done by tightening the jaws on the

rods. The control rods 14 can also be those of the prior art.

They can consist of a tubular element of maximum length

about 6 meters and fitted with maie and female quick couplings at the end,

so that they can be connected between elements. One of the rods is equipped

of an expansion element or fitting 16 to absorb the variation of

length of the set of rods taking into account possible variations in

temperature. The valve 17 comprises the following functional means:

sealing means 18 of the inner channel of the valve body;

anchoring means 19 of the valve 17 in the interior of the tube

production 10;

- sealing means 20 between the valve body and the inside of the tube

10. In one variant, there are two anchor stages, in another

alternatively, only one floor is required.

The valve is lowered after having equipped the element with

suspension of the production line 10 of an adapter 12 which is used to suspend the whole system once it is completely lowered

in the well, to hold the connection elements one after the other

others, to allow their connection between them, to descend the assembly stages after stages. The well being in pressure, an airlock mounted on the shaft of

Christmas, allows the maneuvering procedure in the well. The procedure

operation is conventionally carried out by cable ("wireline"). This procedure

consists of lowering the valve and the connection elements in several stages.

Step 1: the valve attached to its first element of rods 14 is lowered until the upper part of the first element is maintained by the

jaws, thus allowing the suspension and hanging of the first element on the adapter 12. Step 2: The standard rod element is lowered and is

connected to the first element attached to the adapter 12. The jaws of

holding are then opened to allow the descent of the first element attached to the second rod element until the part is maintained

of the standard element by the jaws, thus allowing the suspension and the attachment of its two elements to the adapter 12. Step 3.

This step 3 is identical to step 2 and multiplied as many times as it is

required depending on the number of rods required given the dimension valve installation. Last step: This last step consists of

lower the last element with the suspension head 21 in its upper part and connect it to the last standard element maintained by

the jaws. The jaws are then opened allowing the descent of

the complete assembly and the fitting and locking of the suspension 21 in

the adapter 12.

When applying hydraulic pressure in the control line

15, the different functional means of the valve 17 are activated, that is to say, the

valve opens after tilting of the valve 18, the anchor "dogs" 19 are

radially expanded to immobilize the valve body in the tube, the seal is compressed to rest on the wall of the tube and

sealing.

Figure 3 shows in section more details of the constitution of the

valve 17. The valve 18 is in the closed position thanks to the action of a spring (not shown). It is opened by the displacement of a tube 23 under the action of

thrust of a ring 24 linked to a piston 25. In the presence of pressure

sufficient hydraulic in the chamber 26, the piston presses the tube 23 by

through the ring 24 until the spring 27 is compressed and the said tube which causes the cover 18 to slide over. In the absence of pressure in the chamber 26, the return spring 27 pushes the tube 23 and the seal closes by securing the well. Anchor corners 19 are moved radially by a piston 28

the end of which is cone-shaped on which said anchoring corners 19 rest. The piston 28 is pushed under the corners by pressure

hydraulic in the chamber 29, the displacement of the piston blocking the corners on the wall of the tube 10. Locking means 30 for the position of the piston

anchor 28 keeps this piston in place even when the pressure

dropped in room 30. These locking means can work

according to the ratchet or toothing principle. In FIG. 3, there is a second set: corners 19a, piston 28a, hydraulic chamber 29a,

lock 30a, in the upper part of the pump body. However,

the invention will not be limited to two sets of anchors, in most

realizations only one anchoring set is necessary.

The present valve also comprises sealing means between

the valve body and the production tube 10. This assembly is an element

essential in that in case of failure the safety valve is completely

inoperative and in that it is difficult to seal on a surface

raw like a wall of a production tube. These sealing means comprise a seal assembly 20 which is activated on the wall of the tube

by a piston 31 moved by the hydraulic pressure which is in the

chamber 32. Locking means 33 hold the piston 31 in place even without pressure in chamber 32. A conduit 34 in communication with a connector 22, distributes the

hydraulic pressure in the chambers described above: the valve opening chamber 26, the anchoring chamber (s) 29 and 29a, the chamber

sealing means 32. The connector 22 is connected to the surface by the rods

14 (Figure 2B). It should be noted that the increase in hydraulic pressure in conduit 34 (approximately 35 MPa) transmits the pressure energy in all

rooms at the same time which achieves, substantially at the same time:

the opening of the valve, its anchoring and its tightness in the tubing. When

the hydraulic pressure drops in line 34, the valve closes but remains

in place, anchored and waterproof. A special profile 35 located at the head of the valve body makes it possible to disengage the valve body by pulling and threshing using

a fishing tool adapted to this profile. By beating on the valve body,

we break a series of shear pins which release the piston (s)

anchor 28, 28a, as well as the sealing piston 31. The released valve can

then be brought to the surface.

FIGS. 4A and 4B schematically illustrate the principle of

the seal assembly 20 of the sealing means between the seal carrier body 36 and the production tube 10. The reference (j) designates the radial clearance

between the outside diameter of the seals 37 and the inside diameter of the tube. This clearance is generally of the order of 2.5 mm, but can reach 5 mm. The filling consists of a stack of eight cups 38

Optimized to withstand pressure after being deformed against the wall of the tube. The part 40 constitutes the support on which the stack of cups 38 is compressed, according to an axial force. The part 41 designates the nose of the piston (referenced 31 in FIG. 3). An anti-extrusion cup 39 is

inserted between the first cup and the nose of the piston 41. It should be noted that the

well pressure applies in the direction of the arrow referenced 42.

The optimized shape of the cups 38 results from the general chevron shape called "U" or "V", in which the section of the cups has

symmetry along an axis parallel to the central axis (we can refer to the technical book: "Seals and Sealing Handbook" -Ed. The Trade and

Technical Press Limited, 1985). These seals are suitable for mounting

without backlash, or only a few tenths of a millimeter. In fact, it has been verified that section joints with an axis of symmetry are not compatible with major backlash adjustments, for example greater than

2.5 mm, in particular in the case of resistance to a pressure greater than

5000 PSI, i.e. around 350 MPa.

In order for a seal to make up for a play of a few millimeters, it has been determined that it is necessary in particular to optimize: the deformation capacity of the material, the pressure resistance of this same material, the

level of friction on the lining holder so that the necessary deformations are obtained with less effort.

FIG. 4B schematically illustrates the assembly of the lining once compressed by the action of the piston 41. The interior part of the stack cups seal on the surface 43 of the lining holder 36. The anti-extrusion metal cup 39 deforms to brace against the wall

internal 44 of the production tube. The outer lip of the cups is raised to also rest on the tube and seal the annular space. In

pressure, according to arrow 42, the linings are more strongly supported on the tube while being held by the anti-extrusion cup.

The optimized shape of the sealing cups can be defined as follows:

section of the cup is V-shaped, one of the branches of which is in contact

with the surface of the lining holder (inside diameter of the cup), is shortened 47. Thus, the point 45 of the V is no longer in the position

median of the annular space between the packing cylinder and the wall

inside the tube, but is offset and closer to the packing holder. The branch of the V 46 which supports the most deformation, that which is on the side clearance j, is the longest favoring its displacement under the action of the piston.

The shape of the end of the two branches of the asymmetrical chevron is

suitable for being effectively pressed onto the cylindrical surfaces of the holder

trim and production tube. We have verified by experience and calculations

finite elements that this asymmetrical shape of the cups provides the most regular contact stresses and therefore good resistance to pressure. As material, HNBR rubber of hardness 80 may be used

Shore A which is also suitable for common temperatures in

production wells.

According to the invention, the number of cups is chosen to be eight in the case

a valve suitable for being lowered into a tube of approximately 75 to 80 mm in

internal diameter. The invention is not limited to this number of cups which

may vary depending on the operating pressure and / or the nature of the fluids.

Claims

1. Well safety valve placed in a production tube (10), comprising a body (17) comprising closing means (18) of an internal passage to said body, anchoring means (19) of said body in

said tube, sealing means (20) between said body and the wall of the tube,

said valve comprising means for communicating (14) a pressure

hydraulic between said valve and the surface of the well, characterized in that said sealing, anchoring and sealing means include

hydraulic activation means (25, 28, 31) such that said pressure

hydraulic transmitted from the surface activates said means so as to open

said passage, anchor the valve in the tube and activate the sealing means on the wall of the tube.

2. Valve according to claim 1, wherein said closure means

have a valve (18) held in the closed position by means of

reminder (27), a hydraulic piston (26) providing in pressure a longitudinal displacement of a jacket (23) so as to keep said valve open.

3. Valve according to one of claims 1 or 2, wherein said means

anchor comprises jaws (19) which can be moved radially against the wall of the tube by an anchor jacket (28a) of a hydraulic piston (29a).

4. Valve according to claim 3, wherein the anchoring is mechanically locked by means of immobilization (30a) of the anchoring jacket.

5. Valve according to one of claims 1 to 4, wherein said means

sealing comprises a stack of several annular seals (38) in

resilient material that can be compressed by moving a

compression sleeve (41) of a hydraulic piston.

6. The valve of claim 5, wherein the section of said seals

annular is V-shaped whose branch length is

asymmetrical, the branch in internal contact (47) with the body of the

valve being the shortest, the branch (46) in contact with the wall of the tube, after compression of the stack by the piston, is deformed to enter

contact with the wall of the tube.

7. Valve according to one of claims 5 or 6, wherein said stack

includes a metal cup (39) anti extrusion whose diameter

outside is approximately the outside diameter of the valve body before compression of the stack.

8. Valve according to one of claims 5 to 7, wherein said stack is

consisting of eight cups (38) in V in elastomer of the HNBR type with shore A hardness about 80.

9. Valve according to one of claims 5 to 8, wherein the stack is mechanically kept compressed by means of immobilization of the compression liner.

10. Valve according to one of the preceding claims, in which the means

of hydraulic communication consist of tubular elements joined together by fittings, one end of a first element is connected to the body of said valve, one end of the element

upper is connected to a suspension element.

11. The valve of claim 10, wherein the suspension element is

held in an adapter (12) fixed on the well head and comprising hydraulic communication means with said tubular elements.

12. The valve of claim 11, wherein said adapter comprises

jaws (51a, 51b) with radial displacement intended to be clamped on

said tubular elements.

13. Method of implementing the valve according to one of claims 1 to 12

in a production tube, characterized in that the steps are carried out

following:

- an adapter (12) is assembled on the well head,

- the valve is lowered into the production tube by assembling a number

tubular elements (14) corresponding to the desired dimension,

the valve and its tubular elements are suspended on the adapter by

via a suspension head (21), and the conduit is connected

hydraulic said tubular elements to a pressure source in

area, - the valve is pressurized to open the passage, anchor the valve body in the tube at the level where it is located, compress the stack of

seals to achieve annular sealing.

14. The method as claimed in claim 13, in which the well is made safe by causing the pressure in the valve to drop in order to close said passage closure means without unlocking the anchoring or deactivating.

stacking the annular seals.

15. Method according to one of claims 13 or 14, wherein

disconnects and reassembles the tubular elements before lowering a suitable tool to connect to the head of the valve body and to

unlocking the anchors and the compression means by threshing

stacking.