Valve assembly for drilling mud circulation and associated drilling elements

A valve assembly is for selectively opening and closing a radial aperture provided on a drilling element for drilling mud circulation. The valve assembly includes a valve body that has an inlet aperture and an outlet aperture, and a duct for putting the apertures in communication with each other, thereby defining a mud path (p). The valve assembly includes at least two shutters arranged in a cascade along the direction of the mud path (p), thus forming at least a double barrier.

This application is a National Stage Application of International Application No. PCT/IB2014/064169, filed 1 Sep. 2014, which claims benefit of Serial No. TO2013A000722, filed 6 Sep. 2013 in Italy and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications.

The present invention relates to a valve assembly for drilling mud circulation and to drilling elements, such as, for example, a drill pipe, a tool joint, a sub, with which said valve assembly can be associated.

Said valve assembly is adapted to be associated with a radial aperture in hydraulic communication with an axial duct comprised in the drilling elements with which said valve assembly is associated. The valve assembly according to the present invention comprises at least two radial valves for creating a double barrier for closing a radial aperture during all wellbore drilling steps.

It is known to those skilled in the art that drilling mud has to be circulated through a drill bit located at the end of a series of drilling elements, at the bottom of the well of in proximity thereto, also during the steps of inserting or removing the drill pipes, for the purpose of preventing the uncovered hole from being damaged. In fact, pressure variations that occur at the bottom, which are due to the fact that the pump is in operation while drilling and is then turned off for inserting or removing the pipes, may cause landslides and/or entry of fluids into the wellbore. Circulation of the mud through the bit during the steps of inserting or removing the pipes takes place thanks to a drilling element that, in addition to comprising a through hole extending along the longitudinal axis, also comprises a radial aperture that allows drilling mud to flow in when it cannot be directly pumped through the longitudinal hole. This problem is particularly felt for critical wells, such as, for example, deep, deviated, horizontal and extended-reach wells.

For better performance and operational safety, it is in fact necessary to keep the well bottom pressure constant at desired levels.

Prior-art drilling elements comprise safety valves or valve assemblies that both ensure the necessary safety during the various operating steps and appropriately direct the mud flows to avoid undesired backflows.

Drilling elements are known which comprise valve assemblies wherein a single-barrier valve is arranged at the radial aperture, and a further axial valve is arranged in correspondence to the through hole of the drilling element itself. In addition, in order to ensure that the radial aperture is closed properly, in particular during the drilling steps, a removable plug is inserted in correspondence to the radial aperture. Said removable plug is fixed into a suitable threaded seat comprised in the inner wall of the radial aperture, upstream of said safety valve with respect to the direction of the mud flow entering through said radial aperture. One example of such a drilling element is illustrated in patent document U.S. Pat. No. 3,298,385.

It is known that, during the steps of removing or inserting one or more drill pipes, the radial valve follows the following operating sequence:a) the radial valve stays closed until the pipe to which the valve is connected is wedged into the drill floor and is locked for adding or removing a series of drilling elements, commonly referred to as drill length;b) after unscrewing and removing the removable safety plug, the radial valve is connected to the manifold, which is fed by the mud pump, and is supplied to allow mud circulation in the well bottom;c) at the end of the circulation step that involves it, and after a series of drilling elements or drill length has been added or removed, the radial valve is closed again and, before it is extracted or lowered into the well, the removable safety plug is screwed in again to prevent any mud from leaking through the radial through hole comprised in the drilling element.

The radial aperture is located at such a height as to be easily accessible to an operator. This means that an undesired leak of high-pressure drilling mud through said radial aperture will be directed towards the operators, thus being dangerous.

The above-mentioned patent document does not provide a double barrier in correspondence to the radial aperture during the pipe insertion and removal step, which step requires the presence of operators near the working area. This partial lack of protection arises right after the removable safety plug has been removed, and this may cause important safety problems for the people working in proximity to the valve during the steps of opening and closing the radial aperture. As a matter of fact, following the removal of the safety plug the radial aperture is only kept closed by one shutter. Should said radial valve fail, undesired leakage of mud might occur, causing considerable problems. The lack of safety of such devices is due to the very necessity of removing the protection plug and relying for an indefinite period of time on the radial valve alone for keeping said aperture closed, with circulation pressures that may be in excess of 34474 kpa or even close to 51711 kpa. In such a situation, there will only be one radial valve to prevent an undesired leakage of drilling mud in a direction that might be dangerous for the operators working on the drill floor, near the drill pipes.

Normally said radial valve is a flap valve, which, in case of failure, will not be able to hermetically seal the radial aperture, through which mud could exit due to the pressures involved.

From patent application US2011203670 valve elements are also known which comprise a spherical valve that includes more than one through holes formed inside the spherical shutter, so that it is possible to selectively close and open the radial aperture and the axial longitudinal hole of the drilling element with which said valve element is associated.

From a purely theoretical viewpoint, such a solution appears to be safer than the above-discussed case, but in practice, due to the use of a spherical valve, it does not ensure proper closing and opening of both the radial aperture and the axial longitudinal hole of the drilling element, especially when high pressures are involved.

The present invention aims at solving the above-described technical problems by providing a valve assembly for selectively opening and closing a radial aperture on a drilling element at operating pressures up to 51711 kpa, which provides a double barrier in any operating condition of the drilling rig, thus improving safety during the various operating steps, especially during the steps of inserting and removing drill pipes.

One aspect of the present invention relates to a valve assembly comprising two barriers.

A further aspect of the present invention relates to a drilling element comprising a valve assembly according to the present invention.

With reference to the above-listed Figures, valve assembly2according to the present invention is adapted to selectively open and close a radial aperture84provided on a drilling element8for drilling mud circulation.

For the purposes of the present invention, the term drilling element8refers to any substantially cylindrical device used for drilling an extraction well, which can be inserted into the well itself and which comprises an axial longitudinal hole82and a radial aperture84, e.g. as shown inFIGS. 8A, 8C, 9A and 9B.

Valve assembly2according to the present invention comprises a valve body3, which in turn comprises an inlet aperture3A and an outlet aperture3C. Said valve body3further comprises a duct3B for putting said apertures3A,3C in communication with each other, thereby defining a mud path “p”.

The term mud path “p” refers to the path followed by the drilling mud as it is fed in through radial aperture84of drilling element8, when the same valve assembly2is associated with drilling element8, as is known to a man skilled in the art.

Valve assembly2according to the present invention comprises at least two movable shutters4,6arranged in cascade along the direction of the mud path “p”, thus forming at least a double barrier.

The exemplary and non-limiting embodiments of valve assembly2described below and illustrated in the drawings preferably comprise two shutters4,6. In equivalent non-limiting embodiments, said shutters may be more than two, while nevertheless providing the same technical effect.

Preferably, said at least two shutters4,6can move with respect to said valve assembly2, in particular with respect to valve body3, but they cannot be removed from valve body3. Said at least two shutters4,6are movable and stay operationally connected to the valve body, preferably always and constantly over time.

Preferably, in at least one operating configuration said at least two shutters4,6are arranged along one same first axis “X”, preferably substantially parallel to the direction of mud path “p”, or at least along the same direction.

Preferably, said first axis “X” corresponds to the longitudinal axis of radial aperture84comprised in drilling element8.

Preferably, the shutters comprised in valve assembly2according to the present invention form normally-closed valves.

The term normally-closed valve refers to a valve intended for staying closed, thus preventing the passage of a fluid through the duct3B of the valve body3; the same valve will only open, thereby allowing the passage of a fluid, if appropriately operated.

In the embodiments shown in the annexed drawings, valve assembly2according to the present invention comprises two shutters4,6. In particular, it comprises a first shutter4and a second shutter6. Said first shutter4is arranged downstream, along mud path “p”, with respect to a second shutter6.

More in detail, said first shutter4is arranged in proximity to outlet aperture3C of valve body3, preferably in correspondence thereto, and said second shutter6is arranged in proximity to said inlet aperture3A of valve body3. In the embodiments ofFIGS. 1A, 1Be10A, said second shutter6is to be considered as being arranged in correspondence to inlet aperture3A. As regards the embodiment shown inFIG. 1C, the shutter is to be considered as being arranged in proximity to inlet aperture3A.

Said second shutter6can move with respect to valve assembly2, in particular with respect to valve body3, while still remaining operationally connected to valve assembly2, in particular to valve body3. In particular, said second shutter6is movable, but it remains operationally connected to said valve body3. In all four exemplary and non-limiting embodiments, the second shutter6can be moved while still remaining in the proximity of inlet aperture3A and operationally connected thereto, i.e. second shutter6cannot be removed from valve assembly2. In particular, there is at least one retaining element62that prevents the second shutter6from being completely removed or separated from valve body3.

The second shutter6can be operated automatically, e.g. via an automatic or semi-automatic opening element (not shown).

For the purposes of the present invention, the term shutter operation means the action of switching between the different operating configurations of the shutter.

In general, said second shutter6comprises at least one hooking element7through which said opening element can appropriately activate or deactivate said second shutter6.

The actuation of said second shutter6occurs through a rotational and/or translational movement, e.g. a purely rotational movement, a rotational-translational movement, or a purely translational movement. Upon every movement of said second shutter, the latter always remains operationally connected to valve body3.

In equivalent, non-limiting embodiments, the actuation of said second shutter6is achieved through a complex kinematic movement, which can however provide the same technical effects.

In general, said second shutter6comprises a retaining element62that allows the second shutter6to move between an active or closed configuration, in which it obstructs duct3B and prevents the passage of drilling mud, and an inactive or open configuration, in which it allows the passage of drilling mud.

Said valve assembly2comprises a fastening portion22to be fastened to or associated with a drilling element8. In the embodiments shown inFIGS. 1A and 1B, said fastening portion is a threaded portion. Said fastening portion22is, for example, formed on the outer surface of valve body3, or it is associated therewith as shown inFIGS. 1A, 1B, 2A, 2B, 3A-6C.

Fastening portion22is adapted to engage with a complementary threaded portion on the internal edges of the radial aperture84of a drilling element8.

In the embodiments shown inFIGS. 1C and 10A, valve assembly2is integrated into the drilling element or associable with a drilling element, e.g. through a fastening portion22, or it is arranged in series, for example, with a drilling element8such as a drill pipe string.

In general, said first shutter4is preferably a flap valve.

In particular, said first shutter4rotates about an axis of rotation “Y”, perpendicular to said first axis “X”, along which said first and second shutters4,6are substantially arranged.

Said first shutter4is connected to a first retaining element42, which allows the first shutter4to move correctly between the two operating configurations. Preferably, said retaining element42retains said first shutter4in a closed configuration. In the preferred embodiment, said retaining element42is a hinge, more preferably a hinge comprising an elastic element, e.g. a coil spring.

Said axis of rotation “Y” may be parallel to the longitudinal axis of axial longitudinal hole82comprised in drilling element8with which said valve assembly2is associated. In the preferred embodiment, which is however non-limiting, said axis of rotation “Y” is perpendicular to the longitudinal axis of axial longitudinal hole82comprised in drilling element8with which said valve assembly2is associated, as shown inFIGS. 11B, 12B, 13A and 13B.

The following will describe in detail the technical features and principles of operation of three exemplary and non-limiting embodiments of the radial valve.

Equivalent and/or hybrid embodiments should be considered to fall within the protection scope of the present invention.

FIGS. 1A, 2Aillustrate a first embodiment of valve assembly2, wherein said valve body3is adapted to house, in proximity to inlet aperture3A, said second shutter6. Said inlet aperture3A comprises at least one first orifice31A, preferably four of them equally spaced along a circumference, as shown inFIGS. 4A, 4Be4C. The second shutter6comprises as many second orifices60, which are clearly visible inFIGS. 3A, 4A-4C. Said second shutter6is mounted in a rotatable manner, preferably about an axis parallel to said first axis “X”, on a second retaining element62. In the present embodiment, said second retaining element62is a pin with which said second shutter6is engaged, as shown inFIGS. 3B, 3C, 4Be4C. Said second retaining element62only allows the second shutter6to rotate about an axis parallel to said first axis “X”, while remaining operationally connected to the valve body. Said second shutter6can rotate by a predetermined angle of rotation ranging between 0 and 180°, depending on the number of first and second orifices31A,60included therein.

Said first and second orifices are preferably shaped like a circumference sector, e.g. a shown inFIG. 4A.

The rotation of said second shutter6allows said first orifices31A to be at least partially made to match said second orifices60, thereby creating a mud path “p” through which drilling mud can flow.

In order to allow the drilling mud to flow in a radial direction relative to a drilling element8equipped with valve assembly2according to the present invention during the feeding steps, second shutter6is turned with respect to the portion of valve body3that houses the same second shutter6. The rotation of said second shutter6is such that at least one intake passage or port will be opened. The mud passage section through inlet aperture3A of valve body3is visible inFIGS. 4B, 4C.FIG. 9Ashows mud path “p” on a drilling element8whereto valve assembly2has been applied.

The rotation of said second shutter6is actuated by an automatic or semi-automatic opening device.

The first shutter4, instead, is of the flap type and is normally closed through the effect of a preload of an elastic element, such as a coil spring, comprised in the first retaining element42, in particular a hinge. Said shutter abuts against a jacket31C corresponding to outlet aperture3C of valve body3.

During the radial feeding step, said first shutter4opens through the effect of the thrust exerted by the drilling mud as it flows through.

The axis of aperture of the first shutter4is vertical and parallel to the longitudinal axis of through hole82of drilling element8.

At the end of the step of feeding mud through valve assembly2located at radial aperture84of drilling element8, the absence of mud will cause the first shutter4to close again in abutment with jacket31C, corresponding to outlet aperture3C of valve body3, through the effect of the elastic means, e.g. a coil spring. Subsequently, the automatic or semi-automatic opening device will rotate the second shutter6again to reclose the paths or ports previously created, thus returning into the initial closed configuration. The closing of said ports is due to the fact that said first orifices31A will no longer match said second orifices60, which are movable relative to said first orifices31A.

The rotation of said second shutter6is due to an opening element that, by engaging with at least one clutching element7comprised in said second shutter6, can rotate between the two operating configurations of said second shutter6, while still keeping said shutter operationally connected to the valve body.

Preferably, said at least one clutching element7is arranged externally to valve body3, so that it can interact with said opening device, as shown by way of example inFIGS. 1A, 2A, 3A-4C.

More preferably, there are four of said clutching elements7equally spaced along a circumference and alternated with said second orifices60along the same circumference, as clearly shown inFIG. 3A, 4A.

FIGS. 1B, 2Billustrate a second embodiment wherein said valve body3is adapted to house said second shutter6in proximity to inlet aperture3A. In the closed operating configuration, said inlet aperture3A constrains said second shutter6both axially and radially. Said second shutter6is mounted in a rotatable manner, preferably about an axis parallel to said first axis “X”, and can translate by a finite quantity thanks to at least one second retaining element62, by moving along the same axis “X”. In the present embodiment, said at least one second retaining element62consists of a plurality of cams fixed at one end to the external edges of inlet aperture3A of valve body3, where said second shutter6engages, as shown by way of example inFIGS. 5A-6C. Said retaining element can rotate about an axis perpendicular to said first axis “X” in order to allow the translation of the second shutter6. At the opposite end, said at least one second retaining element62cooperates with a housing61. Said housing61is preferably a groove formed in the second shutter6, as shown inFIGS. 5B, 5C, 6Be6C. Said second retaining element62allows the second shutter6to make a translational movement along an axis parallel to said first axis “X”. Said second shutter6can rotate by a predetermined angle of rotation ranging between 0 and 90°. Said second shutter6can translate for a finite length, such that it can come out of the seat of valve body3and generate a mud path “p” that allows drilling mud to flow through.

The rotational-translational movement of said second shutter6allows the generation of a mud path “p” through which drilling mud can flow.

Said housing61cooperates with said second retaining element62in such a way as to allow the rotation of the second shutter6, by allowing the second end of retaining element62to slide along the perimeter of housing61, preferably in a groove. The same housing61cooperates with said second retaining element62in such a way as to allow the translation of the second shutter, holding the second end of the retaining element and thus defining the maximum translational travel of the second shutter6, as clearly shown inFIGS. 2B and 6B, without the latter being completely removed.

In order to allow the drilling mud to flow in a radial direction relative to a drilling element8equipped with valve assembly2according to the present invention during the feeding steps, the second shutter6is turned with respect to the portion of valve body3that houses the same second shutter6, and is then extracted, without however being removed, from said seat, e.g. by making a translational movement, preferably along said axis “X”, so as to open at least one intake passage or port. The mud passage section through inlet aperture3A of valve body3is visible inFIGS. 6B, 6C.

The rotational-translational movement of said second shutter6is actuated by an automatic or semi-automatic opening device.

In this embodiment as well, the first shutter4is of the flap type and is normally closed, e.g. through the effect of a preload of an elastic element, such as a coil spring, comprised in the first retaining element42, in particular a hinge. Said first shutter is normally closed and abuts against a jacket31C corresponding to outlet aperture3C of valve body3.

During the radial feeding step, said first shutter4opens through the effect of the thrust exerted by the drilling mud as it flows through.

The axis of aperture of the first shutter4is vertical and parallel to the longitudinal axis of through hole82of drilling element8.

At the end of the step of feeding mud through valve assembly2located at radial aperture84of drilling element8, the absence of mud will cause the first shutter4to close again in abutment with jacket31C, corresponding to outlet aperture3C of valve body3, through the effect of the elastic means, e.g. a coil spring. Subsequently, the automatic or semi-automatic opening device will translate and rotate the second shutter6again to reclose the paths or ports previously created, thus returning into the initial closed configuration. The closing of said ports is caused by the obstruction of inlet aperture3A of valve body3by the second shutter6, after it has been translated and sealingly tightened by its rotation.

The rotational-translational movement of said second shutter6occurs thanks to an opening element that, by engaging with at least one clutching element7comprised in said second shutter6, can move said second shutter6between the two operating configurations. In particular, said opening element can turn said second shutter6and also extract the second shutter6, without however removing it, from its seat, e.g. by acting upon said at least one retaining element62or by exerting a translation force on the second shutter6itself.

Preferably, said at least one clutching element7is arranged externally to valve body3, so that it can interact with said opening device, as shown by way of example inFIGS. 1B, 2B, 5A, 6A.

More preferably, there are four of said clutching elements7, equally spaced along a circumference, as shown inFIGS. 5A and 6A.

Said at least one retaining element62preferably comprises an elastic means622adapted to hold said second shutter6in a desired configuration, e.g. closed.

In the illustrated embodiment, said elastic means622acts upon said retaining element62in a manner such that, in the absence of any external forces, in particular for extracting the second shutter6, the same second shutter6will obstruct inlet aperture3A of valve body3thanks to a preload of said elastic means622. This feature significantly improves the efficiency of the closing step and the safety of valve assembly2according to the present invention. Said elastic means622is preferably a coil spring.

FIGS. 1C, 2Cillustrate a third embodiment, wherein said second shutter6is adapted to operate in proximity to inlet aperture3A of valve body3. In the closed operating configuration, said inlet aperture3A is obstructed by said second shutter6, which is positioned between inlet aperture3A and duct3B. Said second shutter6is, for example, a gate shutter. Said second shutter6is mounted in such a way that it can essentially translate or rotate and translate along an axis, preferably along an axis parallel to the axis of rotation “Y” of said first shutter4, as shown by way of example inFIGS. 1C, 2C, 7A and 8A.

Said shutter6translates or rotates and translates in a housing61, preferably an interspace. Said housing61is formed in valve body3or between the outer wall of valve body3and a wall of a drilling element8. As shown in the annexed drawings, particularly inFIGS. 7B and 8B, in the present embodiment valve body3has a hollow cylindrical shape, thus defining an axial aperture that will match axial aperture82of drilling element8with which it will be associated. On the inner face there is outlet aperture3C, whereas inlet aperture3A is located on the outer face. Said second shutter6is arranged coaxial to said valve body3, so that it can rotate and/or translate with respect to said valve body3, in particular with respect to an axis parallel to said axis “Y”. Preferably, the second shutter6is interposed between two portions of valve body3, in particular between a first portion33, comprising outlet aperture3C, and a second portion35, comprising said inlet aperture3A. More in detail, as shown inFIGS. 7B and 8B, the first portion33, the second shutter6and the second portion35consist of three concentric cylinders. Said second portion35may be the very external structure of drilling element8. Said second shutter6can move relative to said two portions33,35of valve body3.

Said second shutter6comprises at least one second orifice60, preferably only one having a circular shape.

In the present embodiment, said at least one second retaining element62is a guide, e.g. made or formed on the second portion35of valve body3, with which hooking element7engages, the latter being rigidly fixed to said second shutter6, as shown inFIGS. 7C and 8C. Said second retaining element62is preferably a guide, more preferably a groove, as shown inFIGS. 1C, 2C, 7A and 8A.

Said second retaining element62is adapted to guide said hooking element7in a manner such that it will translate or rotate and translate about an axis, e.g. perpendicular to said first axis “X”, in order to allow the second shutter6to translate or rotate and translate along an axis substantially parallel to the axis of rotation “Y”. Said translation or rotation-translation allows the second shutter6to clear inlet aperture3A, e.g. by exiting duct3B, or by matching said second orifice60with inlet aperture3A of valve body3and with duct3B.

Said second retaining element62allows the second shutter6to make a translational or rotational-translational movement, essentially along an axis parallel to said axis of rotation “Y”. In the preferred embodiment, said second shutter6rotates by a predetermined angle of rotation ranging between 0 and 90°, and at the same time translates along an axis substantially parallel to said axis “Y”, thereby generating a mud path “p” that allows drilling mud to flow through.

Thanks to the translation or rotation-translation of said second shutter6, a mud path “p” is generated through which drilling mud can flow, as shown by way of example inFIGS. 1C, 8A and 8B.

The second retaining element62is so shaped as to allow moving hooking element7for the purpose of allowing the second shutter6to switch between the two operating configurations.

As shown inFIGS. 7C and 8C, said retaining element62comprises two horizontal section, not aligned with each other and interconnected by a section that is inclined with respect to at least one of them.

Said two horizontal sections respectively allow the second shutter to be kept in an operating configuration, whether open or closed. The inclined section is such that it allows the second shutter6, via hooking element7, to translate or rotate and translate. Said retaining element defines the translational or rotational-translational travel of the second shutter6, as clearly visible inFIGS. 7C and 8C.

In order to allow the drilling mud to flow in a radial direction relative to a drilling element8equipped with valve assembly2according to the present invention during the feeding steps, the second shutter6is translated or rotated and translated with respect to portions33,35of valve body3by moving substantially along said axis “Y”, so as to open at least one intake passage or port. In particular, said intake passage or port is obtained through the at least partial interface between a second orifice60comprised in the second shutter6and inlet aperture3A and duct3B of the valve body. The mud passage section through inlet aperture3A of valve body3is visible inFIGS. 8A and 8B.

The translational or rotational-translational movement of said second shutter6is actuated by an automatic or semi-automatic opening device.

In this embodiment as well, the first shutter4is of the flap type and preferably is normally closed, e.g. through the effect of a preload of an elastic element, such as a coil spring, comprised in the first retaining element42.

All the features of said first shutter4described in the above embodiments will also apply to the following embodiment.

At the end of the step of feeding mud through valve assembly2located at radial aperture84of drilling element8, the absence of mud will cause the first shutter4to close again in abutment with jacket31C, through the effect of the elastic means. Subsequently, the automatic or semi-automatic opening device will translate or rotate and translate the second shutter6again to reclose the paths or ports previously created, thus returning into the initial closed configuration. The closing of such ports is due to the fact that, after the translational or rotational-translational movement, said second orifice60will no longer match inlet aperture3A and duct3B of valve body3.

The translation or rotation-translation of said second shutter6occurs thanks to an opening element that, by engaging with at least on clutching element7comprised in said second shutter6, can move said second shutter6between the two operating configurations. In particular, said opening element can translate or rotate and translate said second shutter6.

Preferably, said at least one clutching element7is arranged externally to valve body3, but internally with respect to the profile of drilling element8, so that it can interact with said opening device, as clearly shown by way of example inFIGS. 7C and 8C.

More preferably, said at least one clutching element7is only one.

FIGS. 10A, 10Billustrate a fourth embodiment, similar to the second embodiment, wherein said valve body3is adapted to house said second shutter6in proximity to inlet aperture3A. In the closed operating configuration, said inlet aperture3A constrains said second shutter6both axially and radially. Said second shutter6is mounted in a rotatable manner, preferably about an axis parallel to said first axis “X”, and can translate by a finite quantity thanks to at least one second retaining element62, by moving along the same axis “X”. In the present embodiment, said at least one second retaining element comprises at least one guide formed in the valve body, and a pin comprised in said second shutter and adapted to move in said guide (not shown in detail in the drawings). Said retaining element, in particular said at least one guide, allows shutter6to rotate about said first axis “X” and then to translate along said axis “X”, and vice versa. Said second retaining element thus allows the second shutter6to make both a rotational movement and a translational movement along said first axis “X”. Said second shutter6can rotate by a predetermined angle of rotation ranging between 0 and 90°. Said second shutter6can translate for a finite length, such that it can come out of the seat of valve body3and generate a mud path “p” that allows drilling mud to flow through.

The rotational-translational movement of said second shutter6allows the generation of a mud path “p” through which drilling mud can flow.

Said guide and said pin of the second retaining element cooperate together to allow the second shutter6to rotate and translate. Said guide thus defines the rotational and translational travel of the second shutter6, as can be understood fromFIGS. 10A-13B, without it being completely removed.

In order to allow the drilling mud to flow in a radial direction relative to a drilling element8equipped with valve assembly2according to the present invention during the feeding steps, the second shutter6is turned with respect to the portion of valve body3that houses the same second shutter6, and is then extracted, without however being removed, from said seat, e.g. by making a translational movement, preferably along said axis “X”, so as to open at least one intake passage or port. The mud passage section through inlet aperture3A of valve body3is visible inFIGS. 10B, 12B and 13B.

The rotational-translational movement of said second shutter6is actuated by an automatic or semi-automatic opening device.

In this embodiment as well, the first shutter4is of the flap type and is normally closed, e.g. through the effect of a preload, in particular a hinge. Said first shutter4is normally closed and abuts against a jacket31C corresponding to outlet aperture3C of valve body3.

During the radial feeding step, said first shutter4opens through the effect of the thrust exerted by the drilling mud as it flows through.

The axis of aperture of the first shutter4is perpendicular to the longitudinal axis of through hole82of drilling element8and perpendicular to said first axis “X”.

This type of first shutter4can be considered to be the preferred embodiment, without however being limiting in nature. This type of first shutter is preferably applicable to all other embodiments of the valve assembly previously described herein.

As shown inFIGS. 13A and 13B, the present embodiment advantageously allows the selective closing of through hole82and of radial aperture84, in particular outlet aperture3C of valve body3, by means of a single mobile shutter without requiring the use of an additional valve element for closing through hole82.

Preferably, the first shutter4is interposed between two portions of valve body3, in particular between a first portion33, comprising outlet aperture3C, and a second portion35, comprising said inlet aperture3A.

At the end of the step of feeding mud through valve assembly2located at radial aperture84of drilling element8, the absence of mud will cause the first shutter4to close again in abutment with jacket31C, corresponding to outlet aperture3C of valve body3, through the effect of said preload. Subsequently, the automatic or semi-automatic opening device will translate and rotate the second shutter6again to reclose the paths or ports previously created, thus returning into the initial closed configuration. The closing of said ports is caused by the obstruction of inlet aperture3A of valve body3by the second shutter6, after it has been translated and sealingly tightened by its rotation.

The rotational-translational movement of said second shutter6occurs thanks to an opening element that, by engaging with at least one clutching element7comprised in said second shutter6, can move said second shutter6between the two operating configurations. In particular, said opening element can turn said second shutter6and also extract the second shutter, without however removing it, from its seat in valve body3, e.g. by exerting a pulling force on the second shutter6itself.

Preferably, said at least one clutching element7is arranged externally to valve body3, so that it can interact with said opening device, as shown by way of example inFIGS. 10A, 10B, 11A, 12A.

More preferably, there are two of said clutching elements7, equally spaced along a diametral direction, as shown inFIGS. 11A and 12A.

In all embodiments, said mobile second shutter6always remains associated with said valve body3, without being removed from said valve body.

Said drilling element8has a substantially cylindrical shape and, as aforementioned, comprises an axial longitudinal hole82and a radial aperture84, with which a valve assembly2according to the present invention is associated.

Said drilling element may comprise an axial valve9, located in correspondence to the axial longitudinal hole82. Said axial valve9is preferably a flap valve adapted to obstruct the flow of drilling mud in an axial direction, in particular opposite to a mud circulation “f” when said valve assembly2is open for mud circulation through radial aperture84, along mud path “p”. The mud circulation “f” is shown by way of example inFIGS. 7A, 9A, 9B. In the open configuration, said axial valve positions itself into a housing86comprised in the walls of axial hole82of the same drilling element8.

In the preferred embodiment, said drilling element does not include an axial valve at axial longitudinal hole82, as shown inFIGS. 13Ae13B. As aforesaid, said axial hole82is advantageously closed by means of said first shutter4of the valve assembly according to the present invention. In fact, when said first shutter4opens said outlet aperture3B, it is the shutter itself that obstructs the flow of drilling mud in an axial direction, in particular opposite to a mud circulation “f” when said valve assembly2is open for mud circulation through radial aperture84, along mud path “p”. Mud circulation “f” is shown by way of example inFIGS. 13A and 13B.

Valve assembly2according to the present invention can operate at working pressures of 51711 kpa, with a drilling mud flow rate ranging between 3,500 and 4,000 liters per minute.

Valve assembly2according to the present invention and drilling element8with which said valve assembly2is associated can improve safety during the drilling process, aiming at safeguarding the people's life, the environment, and the devices used during the drilling operations.

Valve assembly2is applicable to any drilling element and can be used for all oil well drilling activities.

Valve assembly2is also applicable, by way of non-limiting example, for drilling operations employing 6⅝″ diameter drill pipes and 20.3 cm, 21 cm and 21.6 cm drilling elements8.

Valve assembly2according to the present invention allows keeping the mud flow directed as desired by the operator and prevents any backflow of drilling mud.

The possibility of ensuring continuous circulation during the drilling process and of keeping the pressure constant at the bottom of the well also during pipe changes offers the following advantages:it ensures better cleaning of the hole from drilling debris and better stability of the formation, since the walls of the hole being drilled are not subject to stresses caused by pressure variations due to the mud circulation pump being turned on and off, resulting in fewer repair services needed on the drilling battery and less non-productive time (NPT);it eliminates the “balloning” effect and facilitates the detection of a possible entry of layer fluids into the well, so that the problem can be solved quickly and safety is considerably improved;it allows “near balance” drilling, i.e. drilling with a mud weight close to the gradient of the formation pores, thereby facilitating the achievement of well targets that may be unattainable when using standard technologies;it reduces drilling time and costs.

Valve assembly2according to the present invention allows the passage, within the battery of drill pipes, of one or more tools necessary for checks or interventions that might be required during the making of the wellbore, also allowing unscrewing or even cutting a drill pipe in the well.

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