Wellhead cover device and pumping station for a borehole

Abstract

The present invention relates to a pumping station and a wellhead cover device (1), comprising a body (2) provided with a cover (3) and an elbow (4) passing through said cover (3) and oriented orthogonally from an upstream inlet (40) to a downstream outlet (41), characterized in that said elbow (4) internally comprises a cage (5), with an internal volume (50) provided with an inlet (51) connected to said inlet (40); and in that said cover device (1) comprises a valve (6) mounted to move freely inside the internal volume (50) of the cage (5) of said elbow (4), from a closed position of said inlet (51) to at least one open position, and vice versa; said valve (6) being mounted to tilt freely, returning naturally, solely under the effect of gravity and its own weight, to said closed position. Figure for the abstract: Fig. 3

Description

Title of the invention: Device for covering a wellhead and pumping station of a borehole Technical field of the invention

[0001] The present invention falls within the field of drilling and pumping fluid, in particular through an aquifer for pumping water.

[0002] As is known, for the purpose of pumping groundwater, it is common to drill a well through an aquifer, namely a soil containing a groundwater aquifer. During drilling, a vertical cavity is excavated in the ground until a groundwater aquifer is reached. The vertical walls of the cavity are reinforced with a pipe, made of metal or plastic. The upper part of the cavity pipe forms the wellhead. This wellhead is then sealed with a cover.

[0003] Further on, such a wellhead cover device is equipped with several distinct elements, such as pipes ensuring the passage of different flows, in particular the flow of water extracted from the groundwater through a conveying pipe opening at an outlet.

[0004] For this purpose, a pump is also installed, in order to allow the circulation of water from the water table and the supply of said outlet. Such a pump can be directly submerged in the groundwater. The head then allows the passage of an electrical supply to the submerged pump, as well as a pipe to lift the water to the outlet. The pump can also be located outside the borehole, ensuring the water is pumped up the pipe in a known manner. This external pump can be mounted on the cover, which is then equipped with a suction channel for the pumping pipes.

[0005] Valves and controls can be added, allowing in particular the activation of the pump and the flow rate of the water at the outlet of the supply line to be controlled. Other elements, such as valves, can ensure sealing and pressure maintenance, or even manholes, serving as access hatches for well maintenance, in particular allowing access to the pump when it is submerged. These elements, placed on the covering device, then form a pumping station. State of the art

[0006] That being said, a wellhead cover device is known, as described in document FR 2 992 998. Such a wellhead is designed as a single unit, provided with a disc-shaped cover whose lower face is complementaryly shaped to bear against and be fixed to the upper end of the wellbore reinforcement tube. The lower face has several concentric bearing surfaces and radial stiffeners. Furthermore, the head also includes a distribution elbow, with a lower end opening below the cover disc and intended to be sealed to the supply line. The elbow extends orthogonally to an opposite end located above the cover and forming the outlet. This opposite end is fitted with a female thread, intended to be connected, via a male thread, to a distribution network, for example, to supply a domestic drinking water system, or an agricultural watering and irrigation system.

[0007] While such a cover device makes it easy to close the borehole casing and connect it to the water supply line, it presents a drawback related to the penetration of external particles. Indeed, during connection, the outlet is open and communicates with the inside of the device, as well as with the supply line. Particles are then likely to penetrate and pollute the aquifer. This risk of contamination is even greater if successive connections are made, particularly during irrigation periods, resulting in repeated assembly and disassembly of the device on the irrigation network. Furthermore, such pollution can also originate from backflow when several pumping stations are interconnected, due to pressure differences between them.

[0008] In this respect, another drawback of existing cover systems lies in a loss of pressure within the installation, due to water leaks at the joints of the various pipes and conduits, or within the network itself. A leak at atmospheric pressure generates an air intake that can discharge the water column in the supply pipe. A partially or completely emptied column requires the pump to be primed, generating additional electricity costs and reducing the pump's lifespan. Furthermore, once again, the loss of pressure and the drop in the water level of the column results in a reverse flow, promoting contamination.

[0009] In a related manner, working on a pumping station with a column of pressurized water considerably complicates handling, due to the significant load and sudden air intake during atmospheric pressure adjustment by the operator. Description of the invention

[0010] The invention aims to overcome the drawbacks of the prior art by proposing a device for covering a borehole head, designed to ensure a seal of the feed pipe, protecting the water table from any intrusion of external particles. To achieve this, the cover device includes, at the top of the elbow, a cage equipped with a non-return valve. This valve moves from a closed position (blocking the water inlet from the supply pipe) to open positions, and vice versa, under the influence of the flow, and vice versa. Specifically, the valve is hinged to tilt and automatically return to the closed position, naturally under the simple effect of gravity and its own weight. In this tilted position, the valve can open under the simple pressure of the water coming from the pipe. Conversely, without pumping, the valve returns to the closed position, blocking the inlet. Thus, the wellhead cover device, comprising - a body provided with a cover with at least one lower bearing face, shaped complementaryly to cover a tube of said wellhead; - an elbow passing through said cover and ensuring the circulation in a direction extending from upstream to downstream of a flow of fluid, preferably water, said elbow being oriented orthogonally (i) from an upstream inlet opening vertically below said lower face, said inlet being further shaped to cooperate in a watertight connection with an upper end of a feed pipe of said borehole; ii) up to a downstream outlet opening horizontally to the outside. Advantageously, such a cover device is characterized in that said elbow internally comprises a cage, with an internal volume provided with an inlet connected to said inlet; and in that said cover device includes - a movable valve mounted inside the internal volume of the cage of said elbow, from a closed position of said inlet to at least one open position, and vice versa;

[0011] said valve being mounted freely in tilting relative to said elbow, said valve returning naturally, solely under the effect of gravity and its weight, from said at least one opening position to said closing position.

[0012] According to additional, non-limiting features, said valve may include - a sealing device, fitted in addition to a section of said inlet; - a pivot shaft mounted at an upper end of said organ; said cage comprising in its upper part, a cradle shaped complementaryly to receive said pivot shaft in free rotation.

[0013] According to one embodiment, said organ is shaped into a concave shell on the downstream side, so that the circulation of said flow in said direction ensures a pressure against an upstream wall of said shell and pushes said valve towards said at least one open position.

[0014] According to one embodiment, said cage includes at least one access opening at the top, leading into the interior of said cage's internal volume of said elbow; the cover device comprising a hermetic sealing plug for said access opening.

[0015] According to one embodiment, said plug includes a lower edge, which locks said pivot shaft of the valve within the cradle, in airtight closure of said access opening by said plug.

[0016] According to one embodiment, said stopper includes at least one sensor for measuring the displacement of said valve.

[0017] According to one embodiment, said cover device may include locking means for closing said cap, in the form of at least two rings integral with said body and said cap.

[0018] According to one embodiment, said outlet comprises a threaded female part.

[0019] According to one embodiment, said cover device may include a grab handle attached as a removable fixing to said body.

[0020] According to one embodiment, said cover device may include at least one hook projecting from said body, said hook being open towards the underside of said cover.

[0021] The invention further relates to a wellbore pumping station equipped with said wellbore head cover device. In particular, such a pumping station includes - a reinforcement tube for a cavity of said borehole, with an upper end forming a head of said borehole; - pumping means, in the form of a submersible or external pump; - a supply line extending along said tube to said wellhead. Advantageously, it is characterized in that it comprises, connected to said line and covering said wellhead, a device for covering a wellhead of said borehole according to the invention.

[0022] According to additional, non-limiting features, such a pumping station may include, connected to said cover device, means for controlling said pump and the flow rate of the supply line. Drawings

[0023] Other features and advantages of the invention will become apparent from the following detailed description of non-limiting embodiments of the invention, with reference to the accompanying figures, in which:

[0024] [Fig. 1] schematically represents a perspective view of an embodiment of a pumping station equipped with a wellhead cover device;

[0025] [Fig.2] schematically represents a view along a vertical section of an embodiment of the drilling head device, showing in particular a valve in the closed position;

[0026] [Fig.3] schematically represents a view similar to [Fig.2], showing in particular a valve in a first open position;

[0027] [Fig.4] schematically represents a view similar to [Fig.3], showing in particular a valve in a second opening position;

[0028] [Fig.5] schematically represents a view similar to [Fig.2], showing in particular the open top cap, giving access to the inside of the device and allowing the insertion and extraction of the valve;

[0029] [Fig.6] schematically represents a perspective view of one embodiment of the valve;

[0030] [Fig.7] schematically represents a profile view of [Fig.6]; and

[0031] [Fig.8] schematically represents an elevation view of [Fig.6]. Detailed description

[0032] The present invention relates to the pumping of fluid, in particular water, drawn from an underground aquifer through a borehole. Once the borehole is drilled, the cavity is reinforced with a casing, within which is placed at least one pipe for conveying the upward flow from the bottom of the well, as well as optionally a submersible pump and its electrical power supply wiring. Next, it is necessary to seal the upper part of the well, namely the wellhead.

[0033] For this purpose, the invention relates to a device 1 for covering a borehole head.

[0034] Such a cover device 1 comprises a body 2. Such body 2 serves as a base to bear against the upper part of the borehole reinforcement tube. The body 2 also serves as a support for various elements, as detailed below.

[0035] Further on, said body 2 is provided with a cover 3. Such a cover 3 has at least one lower bearing face 30, shaped complementaryly to cover a tube of said wellhead. In particular, the cover 3 has a complementary shape to cover the upper end of the tube, possibly to cover the perimeter and an area around said tube, with its lower face 30 bearing against the edge of the upper end of said tube. According to a preferred embodiment, said cover 3 advantageously has a circular shape, forming a covering disc, with an annular peripheral wall 31 extending in projection under said disc.

[0036] Relatedly, the cover 3 also has an upper face 32. Several elements of the cover device 1 can be attached to the body 2, to the upper face 32 of the cover 3 and / or along its peripheral wall 31.

[0037] As such, the cover device 1 includes an elbow 4 passing through said cover 3. Such an elbow 4 forms a channel and ensures the circulation in a direction extending from upstream to downstream of a flow of fluid, preferably water. It should be noted that the circulation of the fluid according to said flow is carried out by means of pumping, namely the operation of at least one submersible pump or one provided externally.

[0038] Further on, said elbow 4 is oriented orthogonally or substantially orthogonally. In particular, the elbow 4 extends from an upstream inlet 40 opening vertically below said lower face 30 of cover 3. Such an inlet 40 is further formed to cooperate in a watertight connection with an upper end of the feed line of said borehole. Furthermore, said elbow 4 extends to a downstream outlet 41 opening horizontally to the outside, namely above the upper face 32 of the cover 3. According to a preferred embodiment, said outlet 41 includes a threaded female part, facilitating the cleaning of this thread located on the periphery of said outlet 41. Thus, the elbow 4 ensures the connection between the inside and outside of the well, allowing the flow to circulate through the device 1 when it is positioned covering said borehole.

[0039] According to one embodiment, the elbow 4 and the cover 3 are integral parts of said body 2, in a monobloc fashion, namely forming a single piece of the same material. Preferably, said body 2 can be made of a plastic or composite material, preferably by plastic molding or injection. It should be noted that reinforcements can be provided on the lower face 30 of the cover, in order to improve the rigidity of the cover device 1.

[0040] Advantageously, the cover device 1 provides for limiting the risks of pollution and contamination of the well and pipeline located upstream.

[0041] To this end, said elbow 4 internally comprises a cage 5, with an internal volume 50 provided with an inlet 51 connected to said inlet 40. Thus, the elbow 4 comprises, on the one hand, upstream, a first portion extending from the inlet 40 to the inlet 51, opening into said internal volume 50 and connecting the conduit to the interior of the cage 5. On the other hand, downstream, the elbow 4 comprises a second portion extending from the internal volume 50 to the outlet 41, connecting the cage 5 to the outside. Furthermore, the cross-section of said inlet 51 is oriented angularly with respect to the horizontal and is located along the first portion forming the bend of the elbow 4 from the inlet 40. In particular, the cross-section of the inlet 51 is inclined at an angle of at least 45°, and in particular at an angle greater than 45°.Preferably, the inlet 51 is located at the end of the first turning portion of the bend 4 and its cross-section is inclined at an angle of approximately 90°, preferably at an angle of 90°, namely that said cross-section extends substantially vertically, preferably vertically.

[0042] According to the corresponding embodiment, said cage 5 is an integral part of the one-piece body 2 of the cover device 1.

[0043] Furthermore, said cover device 1 further includes a movable flap 6 mounted inside the internal volume 50 of the cage 5 of said elbow 4. Therefore, cage 5 has an internal volume 50 sized to ensure the mobility of said valve 6.

[0044] Accordingly, such a valve 6 is provided to be movable from a closed position of said inlet 51 to at least one open position, and vice versa. In particular, said valve 6 can move through several opening positions, corresponding to different degrees of closure of the inlet 51. In other words, the more the valve 6 is open, the greater the quantity of fluid flowing through said inlet 51.

[0045] Advantageously, said valve 6 is mounted to tilt freely relative to said elbow 4. Furthermore, said valve 6 naturally returns, solely under the effect of gravity and its weight (i.e., its mass), from said at least one open position to said closed position. In other words, said valve 6 oscillates between the closed position, which is its stable equilibrium state, and one or more open positions, in which the valve 6 is unbalanced and tends to return to the equilibrium position, by closing said inlet 51.

[0046] It will be noted that said valve 6 is therefore located after the inlet 51, according to the direction of flow of the flux from upstream to downstream.

[0047] According to a preferred embodiment, said valve 6 is provided to pivot in suspension. In other words, the valve 6 is held superiorly, at the level of a retention point and extends below said point in the closed position of said arrival 51. To this end, said valve 6 includes a closing element 60, complementary to a section of said inlet 51. In other words, the element 60 of the valve 6 has the same shape, with similar dimensions, as the inlet 51, so as to close said inlet 51 in the closed position. Preferably, since said inlet 51 has a circular cross-section, said element 60 has a cross-section of identical shape, with an equal or preferably larger diameter, to close over the downstream edge of said inlet 51. According to one embodiment, said component 60 is shaped into a concave shell on the downstream side. In other words, the component 60 is hollow towards the outlet 41, or convex towards the inlet 40, namely on the side of the inlet 51. Organ 60 can have any shape, rounded, conical or frustoconical. Preferably, organ 60 is in the form of a hemispherical shell or a spherical cap. This shape provides a surface for pushing the flow when it is circulated in the direction in question, which exerts pressure against an upstream wall of the shell and pushes the valve 6 towards at least one open position. Furthermore, depending on the flow rate, the force applied against the upstream face of the component 60 pushes the latter more or less downstream.

[0048] Said valve 6 also includes a pivot shaft 61 mounted at an upper end of said member 60. According to a preferred embodiment, the valve 6 includes an offset arm 62 connecting the member 60 to its shaft 61. Such an arm 62 can have any shape, preferably arched with a hollow on the side of the inlet 51 when said valve 6 is in the closed position.

[0049] Furthermore, said cage 5 includes, in its upper part, a cradle 52 shaped to receive said pivot shaft 61 for free rotation. Thus, by placing the shaft 61 within the cradle 52, the element 6 can freely oscillate in suspension, via a rotating or pivoting joint. When the flow is initiated, the pressure against the element 60 tilts said valve 6 towards an open position, which is proportionally open depending on the flow rate. Conversely, when the fluid is not flowing, the weight of the valve 6 allows it to naturally return to its equilibrium position, overlapping downstream and closing the inlet 51. Figures 2 to 4 show different positions of the valve 6, in particular two different opening positions, in which said valve 6 is more or less retracted, depending on the quantity of fluid passing through the inlet 51. A preferred embodiment of said valve 6 is shown in Figures 6 to 8, depicting a member 60 with a spherical dome-shaped shell connected to an arched, U- or C-shaped offset arm 62, which connects said member 60 at one end fixed to the downstream edge of said shell, to a pivot shaft 61 at the opposite end. Furthermore, said shaft 61 has a cylindrical shape with two ends projecting laterally on either side of the opposite end of said arm 62, along an axis aligned with the median plane containing the shell of said member 60.

[0050] It should be noted that said valve 6 can be made of any type of material, in particular metal, plastic or composite, preferably from a single molded or machined piece.

[0051] Thus, the rotational link of the valve 6 within the cradle 52 consists of a simple and durable mechanical system, requiring little maintenance. Furthermore, this 6-way valve and its mechanical linkage offer better sealing than conventional valves, particularly spring-loaded valves whose effectiveness decreases over time. In addition, the 6-way valve and its mechanical linkage reduce the number of fittings and seals, which are potential sources of leaks.

[0052] Furthermore, the balanced closed position of the valve 6 allows the water column level to be maintained during an intervention inside the cage 5, avoiding any unloading and emptying, saving water resources. Conversely, the opening of the valve 6 occurs freely during pumping, under the effect of the pumped water flow, tilting said valve 6 more or less.

[0053] As such, the cover device 1 is intended for a fluid with low viscosity, preferably water, but also, without limitation, liquids from the agri-food sector, such as wine or juices, or even fluid oils, or fuels, or even fluids such as dense gases. Viscosity refers to dynamic viscosity, expressed in Pascal seconds (Pas s), formerly the Poiseuille (PI). Low viscosity is understood in relation to the viscosity of water, particularly at a temperature of 20°C (degrees Celsius), which is approximately 1 x 10³ Pa s. Low viscosity is therefore equivalent to, preferably less than or equal to, the viscosity of water at the same temperature. In addition, the viscosity of the circulating fluid must have a value that allows flow through the inlet 51 and along the wall of the valve 6 element 60, in particular limiting the laminar flow in contact with these walls.

[0054] According to one embodiment, said cage 5 includes at least one access opening 53, opening into the interior of said internal volume 50 of said elbow 4. In addition, the cover device 1 includes a hermetic closure plug 7 for said access opening 53. Therefore, said plug 7 has a shape and dimensions complementary to those of said opening 53. Preferably, the plug 7 has a generally cylindrical shape, cooperating with a circular section of said opening 53. According to a preferred embodiment, the plug 7 includes at the bottom a male part with a thread, which cooperates by screwing with a complementary thread provided at the top within said opening 53.

[0055] According to one embodiment, the shaft 61 of the valve 6 is held within the cradle 52, simply by virtue of its weight and the rounded concave shape of said cradle 52. According to a preferred embodiment, said plug 7 comprises a lower edge, which locks said pivot shaft 61 of the valve 6 within the cradle 52, hermetically sealing said access opening 53 by said plug 7. In other words, screwing the plug 7 with the opening 53 closes the cradle 52 from above, preventing the shaft 61 from being extracted, thus blocked from above, while allowing the rotation of said shaft 61 and leaving the valve 6 free to open and close as the flow passes through. Conversely, once the cap 7 is removed, access through the opening 53 allows the flap 6 to be removed.

[0056] It should be noted that the opening 53 is dimensioned to allow the insertion and extraction of said valve 6, facilitating its maintenance and replacement, as seen in [Fig.5].

[0057] According to one embodiment, said cover device 2 provides for controlling several parameters, in particular for detecting downstream fluid leaks, through the unsolicited movement of said valve 6. To achieve this, said plug 7 includes at least one sensor for measuring the displacement of said valve 6. According to another embodiment, other parameters can be measured, through sensors positioned within said cap 7, positioning them as close as possible inside the body 2 of the device 1, while making them easily accessible. These sensors can measure, but are not limited to, the flow rate or quantity of fluid passing through the inlet 51 or entering the cage 5, measure the internal temperature of the cage 5 or of the circulating fluid, measure the air pressure inside said cage 5, or measure the water quality and detect the presence of pollutants or contaminants. Thus, it is possible to monitor the volumes of water used and the activation periods, facilitating the management of the water resource, but also allowing controls by a dedicated stakeholder, for example in the event of drought and restrictions related to a regulated use of groundwater.

[0058] Furthermore, said cover device 1 may include warning means during pumping, namely during the circulation of the fluid by actuation of the pump. These warning means may be of any form, including an audible alarm, but preferably visual, in the form of one or more indicator lights (green or red). Combined with the detection of the movement of valve 6, these alert methods make it easy to check the proper functioning of the installation, but also to visualize the presence of a leak or a malfunction.

[0059] According to one embodiment, the cover device 1 may be equipped with means for connecting to a communication network, preferably wireless. These means may be of any type, including electronic or computer-based, enabling the remote transmission of recorded data, such as water consumption.

[0060] According to one embodiment, as shown in [Fig. 1], said cover device 1 comprises locking means for said cap, in the form of at least two rings 8 integral with said body 2 and said cap 7. These rings 8 extend laterally in the form of loops, allowing the cap 7 to be connected to the body 2 by means of a link securing the two elements together. Such a link may be a padlock or official seals.

[0061] According to one embodiment, said cover device 2 includes a gripping hoop 9 attached as a removable fixing to said body 2. Such an arch 9 serves as a handle, allowing manual lifting of the device 1 or by means of a lifting device or equipment. According to a preferred embodiment, as shown in [Fig. 1], said hoop 1 has a tubular, arched shape with a substantially horizontal central portion, extended by two vertical portions on each side, the ends of which are fixed to said body 2. In particular, recesses may be provided within said body 21, at the level of the cover 3, especially around its perimeter. These diametrically opposed recesses allow the ends of said hoop 9 to be fixed. In addition, the fixing of the hoop 9 can be provided to be removable, allowing its placement during the lifting operations for the installation and removal of the cover device 1, and then its removal once in place.

[0062] According to one embodiment, said cover device 2 includes at least one hook 10 projecting from said body 2, said hook 10 being open towards the underside of said cover 3. Such a hook 10, oriented in this way, allows the cover device 2 to be lifted in suspension from at least one side, using lifting equipment or machinery, thus securing the removal and maintenance operation, in particular the connection and disconnection of the inlet 40 with the upper end of the pipe, as well as the positioning of the lower face 30 of the cover 3 on the wellhead. This hook 10 can also be used to secure an element with the body 2, through a rope or strap, such as the pump during its maintenance.

[0063] The invention also relates to a wellbore pumping station. Such a station comprises a reinforcement tube for a cavity of said wellbore, with an upper end forming a wellbore head. The said station also includes pumping means, in the form of a submersible or external pump, as well as a supply line extending along said tube to said head. Relatedly, the station may include other piping, such as electrical power wiring for the submersible pump, and piping for airflow, particularly for vacuum, for an external pump. Advantageously, said station includes, connected to said piping and covering said wellhead, a device 1 for covering a wellhead of said borehole according to the invention and in the embodiments described above.

[0064] According to one embodiment, said station comprises, connected to said cover device 1, means for controlling said pump and the flow rate of the supply line. Such control means may be of any type, such as a switch or a valve, or even a solenoid valve. These control means may also be controlled locally or remotely, via a communication network, preferably wireless, through a human-machine interface.

[0065] Thus, the pumping station and its wellhead cover device 1 protect the interior from all external elements, such as dust, pebbles, or vegetation, as well as insects and animals, which could pollute the water, clog the pipes, or damage the submersible pump. The invention therefore ensures the quality of the groundwater. Furthermore, the invention allows for the easy and safe removal of the submersible pump and the power cables, regardless of the drilling depth. The cover device 1 is quick and easy to install, generating considerable time savings for an installer with plumbing experience, without additional qualifications. Furthermore, being permanently connected to the wellhead tube, the cover device 1 is accessible, facilitating any maintenance and troubleshooting intervention. Finally, the cover device 1 with its one-piece body, as well as its one-piece flap 6 with a simple mechanical link, provide a low cost and increased longevity.

Claims

Demands

1. A device (1) for covering a borehole head, comprising: - a body (2) provided with a cover (3) having at least one lower bearing face (30), further shaped to cover a tube of said borehole head; - an elbow (4) passing through said cover (3) and ensuring the circulation in a direction extending from upstream to downstream of a flow of fluid, preferably water, said elbow (4) being oriented orthogonally i) from an upstream inlet (40) opening vertically below said lower face (30), said inlet (40) being further shaped to cooperate in a watertight connection with an upper end of a feed line of said borehole; ii) to a downstream outlet (41) opening horizontally to the outside;characterized in that said elbow (4) internally comprises a cage (5), with an internal volume (50) provided with an inlet (51) connected to said inlet (40), said inlet (51) being located at the end of a rotating portion of the elbow so that a cross-section of the inlet (51) extends substantially vertically, preferably vertically; and in that said cover device (1) comprises - a flap (6) mounted movable within the internal volume (50) of the cage (5) of said elbow (4), from a closed position of said inlet (51) to at least one open position, and vice versa; said flap (6) being mounted freely in a tilting position relative to said elbow (4), said flap (6) returning naturally, solely under the effect of gravity and its weight, from said at least one open position to said closed position.

2. Cover device (1) according to the preceding claim, characterized in that said valve (6) comprises - a sealing member (60), complementaryly formed to a section of said inlet (51); - a pivot shaft (61) mounted at an upper end of said member (60); said cage (5) comprising in its upper part, a cradle (52) shaped complementaryly to receive said pivot shaft (61) in free rotation.

3. Cover device (1) according to the preceding claim, characterized in that - said member (60) is shaped into a concave shell on the downstream side, so that the circulation of said flow in said direction ensures a pressure against an upstream wall of said shell and pushes said valve (6) towards said at least one open position.

4. Cover device (1) according to any one of the preceding claims, characterized in that said cage (5) comprises at the top - at least one access opening (53), opening into the interior of said internal volume (50) of the cage (5) of said elbow (4); the cover device (1) comprising - a hermetic closure plug (7) for said access opening (51).

5. Cover device (1) according to claims 2 and 4, characterized in that - said cap (7) comprises a lower edge, coming to lock said pivot shaft (61) of the flap (6) within the cradle, in airtight closure of said access opening (51) by said cap (7).

6. Cover device (1) according to any one of the preceding claims 4 or 5, characterized in that - said cap (7) comprises at least one sensor for measuring the displacement of said flap (6).

7. Cover device (1) according to any one of claims 4 to 6, characterized in that it comprises - locking means for closing said cap (7), in the form of at least two rings (8) integral with said body (2) and said cap (7).

8. Cover device (1) according to any one of the preceding claims, characterized in that - said outlet (41) comprises a threaded female part.

9. Cover device (1) according to any one of the preceding claims, characterized in that it comprises - a gripping hoop (9) attached as a removable attachment to said body (2).

10. Cover device (1) according to any one of the preceding claims, characterized in that it comprises - at least one hook (10) projecting from said body (2), said hook (10) being open towards the lower face (30) of said cover (3).

11. A wellbore pumping station, comprising - a reinforcement tube for a cavity of said wellbore, with an upper end forming a wellhead; - pumping means, in the form of a submersible or external pump; - a supply line extending along said tube to said wellhead; characterized in that it comprises - connected to said line and covering said wellhead, a covering device (1) for a wellhead of said wellbore according to any one of the preceding claims.

12. Pumping station according to the preceding claim characterized in that it comprises - connected to said cover device (1), means for controlling said pump and flow rate of the supply line.

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