RU2527054C1 - Spherical circular rotary preventer - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: spherical circular rotary preventer contains a case with the central feedthrough hole and a circular bore where a piston and a base plate are placed between the piston and case. In a wall of the circular bore there are hydraulic channels for interaction of its cavities with a hydraulic drive. At the case there is a cover with a radial stopper in it and a flange with the central feedthrough hole installed hermetically in its central threaded opening. A rotatable hollow shell is placed at rolling contact bearings. The upper bearing with the central feedthrough hole is connected hermetically to the upper part of the shell cavity; it contains a spherical groove. Under the upper bearing there is a lower bearing with the central feedthrough hole, which is installed hermetically at the piston butt end and is rotatable at rolling contact bearings and sleeve bearings; it interacts hermetically with the lower part of the shell. A sealing element is placed between the upper and lower bearings and interacts by its upper part with the spherical groove in the upper bearing and by its lower part to the butt end of the lower bearing.

EFFECT: increase in total life between overhauls, improvement in reliability and safety of operation as well as reduction of operation costs.

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Description

The invention relates to equipment for sealing the mouth of oil and gas wells during their construction, development and repair in order to ensure safety, prevention and elimination of oil and gas manifestations, protection of the subsoil and the environment.

The well-known annular type preventer PU2 (Abubakirov V.F. et al. “Drilling, blow-out and wellhead equipment” Reference book: V 2 vol. T.1. - M .: IRC Gazprom LLC, 2007, p. 499 -500, Fig.8.22 "b"), containing:

- a housing with a central bore and an annular bore,

- a cover with a central passage hole and a spherical cavity,

- a plunger movably mounted in the annular bore of the housing,

- a seal installed on the end of the plunger in a spherical recess of the cover,

- faceplate located between the body and the cover,

- hydraulic channels for connecting the annular bore of the housing with a hydraulic actuator.

A disadvantage of the known preventer is its limited operational capabilities, excluding the possibility of its use when drilling with a sealed wellhead. This is due to the design of the preventer, in which there are no rolling bearings that allow the seal to rotate together with the drill string. Therefore, if it is necessary to liquidate an emergency situation, for example, a drill string sticking, the drill pipe sealed at the mouth, being squeezed by a sealant motionless relative to the body, can rotate in it only in the cranking mode with minimum revolutions. In this case, in contact the outer surface of the pipe — the inner surface of the seal — sliding friction will occur, the force from which the inner surface of the seal will undergo intensive abrasive wear, which reduces the life of the seal and requires increased operating costs for its replacement. In addition, increased wear of the seal reduces the reliability of the known device, because uncontrolled wear of the sealant can lead to leaks in the area of its contact with the pipe being sealed and, consequently, to the release of the borehole medium with an emergency.

Known rotating universal hydraulic preventer (RF patent No. 2208126, IPC E21B 33/06, published July 10, 2003), containing:

- a housing with a central bore and an annular bore,

- a cover with a central passage hole,

- a sleeve rotating in rolling bearings located in the housing and the cover, and having a spherical recess,

- a piston movably mounted in the annular bore of the housing,

- a sealing element located on the end surface of the piston and interacting with a spherical recess of the sleeve,

- a faceplate made in the form of a sleeve located between the piston and the sleeve,

- hydraulic channels for connecting the cavities of the lid and the housing with a hydraulic actuator.

A disadvantage of the known preventer is the increased operational labor costs for its maintenance or repair, due to the design features, which require replacing the sealing element of the dismantling of the cover and sleeve mounted on rolling bearings. Reassembling the sleeve involves the operation of installing rolling bearings with adjustable interference and centering, which is impossible to perform in the field. Therefore, for disassembly, a known device must be transported to the equipment repair workshop, which increases the downtime of the drilling rig.

A disadvantage of the known preventer is also the low reliability and safety during operation. This is due to the fact that the piston, after closing the sealing element on the sealed pipe, will rotate together with the sleeve and at the same time sliding friction occurs in contact of its inner surface and seals with the housing bore. As a result, abrasive wear of the seals will occur with a loss of their tightness and fluid leakage from the hydraulic drive when it is supplied to move the piston to close the sealing element, as a result of which the force of pressing the sealing element to the pipe to be sealed may be insufficient to counter the pressure of the well at its wellhead. This circumstance will lead to gaps in the borehole fluid in the zone of contact of the sealing element with the pipe being sealed, which, due to the solid phase and sludge content in the borehole fluid, can cause abrasive wear of the sealing element and, ultimately, to eject the wellbore fluid in an emergency.

The combination of these circumstances increases the complexity and operating costs of servicing a well-known preventer, reduces the overhaul period, reduces the reliability and safety of its operation.

The objective of the invention is to provide a technical solution to the preventer that does not have the above disadvantages.

To ensure this technical result in a known preventer containing

- a housing with a central bore and an annular bore,

- a cover with a central threaded hole,

- a piston movably mounted in the annular bore of the housing,

- a hollow sleeve placed in the housing and the cover with the possibility of rotation on the rolling bearings,

- a spherical recess located under the lid,

- a sealing element located above the end surface of the piston and interacting with a spherical recess,

- faceplate located between the piston and the housing,

- hydraulic channels for communication of the over-piston and under-piston cavities of the annular bore of the housing with a hydraulic actuator,

ACCORDING TO THE INVENTION

- additionally equipped with a flange made with a Central passage hole and hermetically connected to the cover,

- radial sleeve stopper mounted in the cover,

- supporting the top with a Central passage hole, hermetically connected to the upper part of the cavity of the sleeve and containing a spherical recess,

- a lower support with a central bore, hermetically mounted on the piston end with the possibility of rotation on the rolling and sliding bearings and hermetically interacting with the lower part of the sleeve,

- while the sealing element is located between the upper and lower supports and interacts with them.

The invention is illustrated by drawings, where:

- figure 1 shows a General view of the preventer in section, the sealing element is open;

- figure 2 is a General view of the preventer in section, the sealing element is closed on a pipe lowered into the well;

- figure 3 is a General view of the preventer in the context, the upper parts are dismantled in order to replace the sealing element.

The inventive annular spherical rotary preventer comprises a housing 1 (Fig. 1) with a central passage bore 2 located in the lower part for passing pipes 3 and an annular bore 4 in which the piston 5 is placed and a faceplate 6 installed between the piston 5 and the housing 1. In the ring wall bores 4 are made of hydraulic channels 7 and 8, connecting its cavity with a hydraulic actuator (not shown) to supply or discharge hydraulic pressure.

On the casing 1, the cover 11 is fixed on top with pins 9 and nuts 10 with a stopper 12 installed in it and placed in its central threaded hole 13 with a flange 14 with a central bore hole 15. In the casing 1, a sleeve 16 is mounted rotatably mounted in the rolling bearings 17 and 18. A cavity 19 is made in the sleeve 16, in which the upper support 20 is fixed by means of a threaded connection, under which the lower support 21 is located. The upper support 20 has a central opening 22 and a spherical recess 23 that interacts with the upper part of the seal element 24. The lower support 21 is mounted on the end face 25 of the piston 5 with the possibility of rotation on the bearings 26 and sliding 27. The lower part of the sealing element 24 interacts with the end surface 28 of the support of the lower 21. To determine the position of the sealing element 24 and assess its wear, the preventer is equipped with pointer 29. The tightness of the piston 5 and the faceplate 6 relative to the housing 1 is achieved by sealing cuffs 30, and the cover 11, flange 14, the upper support 20 and the lower support 21 are sealed with sealing cuffs 31.

The inventive annular spherical rotary preventer operates as follows.

The preventer is installed and fixed at the wellhead (the landing flange of the downstream equipment is not shown).

When carrying out tripping operations (Fig. 1), the pipe string 3 is lowered through the central hole 15 of the flange 14, the sealing element 24 and the central passage hole 2 of the housing 1. The preventer is open, i.e. the sealing element 24 is not closed on the pipe 3, because not pressed by piston 5.

To carry out the sealing of the wellhead, hydraulic fluid is fed into the hydraulic channel 7 of the preventer body 1 to create pressure under the piston 5. Under the action of the fluid pressure, the piston 5 (Fig. 2) rises up and acts on the sealing element 24 from below from below, moving it upwards spherical recess 23 of the support of the upper 20 preventer. The sealing element 24, elastically deformed when interacting with the spherical recess 23, closes, covering the deflated pipe 3, and overlaps the Central hole 22 of the support of the upper 20, thereby sealing the wellhead. Next, open the downstream ram preventer (not shown) and under the sealing element 24, the lower bearing 21 and the piston 5, the pressure of the borehole medium arises, acting on the piston 5 and the lower bearing 21, which increases the sealing margin and improves the reliability of the inventive preventer.

To carry out drilling operations, the rotation of the deflated pipe string 3 begins, which due to the friction forces resulting from the compression of the material of the sealing element 24 in the contact zones to the surface to be sealed, is transferred to the support of the lower 21 and the support of the upper 20, and, further, the sleeve 16 starting rotation in rolling bearings 17 and 18. As a result of the interaction of the sealing surfaces of the sealing collars 30 and 31 with the corresponding sealing surfaces, friction forces appear, creating a moment of resistance, favoring rotation. The moment of resistance depends on the pressing force of the sealing material, and the pressing force depends on the contact area in the sealing zone. The contact area of the sealing cuffs 30 is larger than the contact area of the sealing cuffs 31, due to their larger diameter and number, therefore, the moment of resistance to rotation of the piston 5 will be greater than the moment of resistance to rotation of the support lower 21, so that the piston 5 will be stationary relative to the housing 1, and the support lower 21 will rotate relative to the piston 5 together with the sealing element 24 and the sleeve 16.

If it is necessary to open the preventer, the hydraulic fluid is supplied to the hydraulic channel 8 (Fig. 1), the piston 5 lowers under pressure, the sealing element 24, under the action of the elastic properties of the material, returns to its original position and releases the pipe string 3 for the necessary work.

Thus, during the operation of the inventive preventer, the sealing collars 30 of the piston 5 do not rotate with friction on the surface to be sealed, therefore, they wear out less, the probability of failure of them, as less loaded, decreases, which increases the overall overhaul period of the preventer, reduces operating costs and increases operational safety .

The position indicator 29 of the sealing element 24 moves together with the piston 5 and the sealing element 24, signals an increase in the stroke of the piston 5 that occurs when the working edge of the sealing element 24 is worn, and allows to evaluate the degree of its wear to determine the need for replacement.

If necessary, replace the sealing element 24 block the inner channel of a deflated pipe string 3 with a ball valve (not shown) and close the ram preventer (not shown) on it. To replace the sealing element 24 (Fig. 3), dismantle the flange 14 and the upper support 20. To fix the sleeve 16 from rotation when unscrewing the support of the upper 20, screw the stopper 12 into the groove 32 of the sleeve 16. Remove the sealing element 24, install a replaceable sealing element, and collect the preventer in reverse order.

The accelerated and non-disassembling of the preventer replacement of the sealing element 24 at the wellhead reduces the down time of the rig and protects the components and parts from additional wear, thereby increasing reliability.

Thus, the use of the inventive preventer provides an increase in the total overhaul period, increasing the reliability and safety of work, as well as reducing operating costs.

Claims (1)

A spherical rotary annular preventer comprising a housing with a central passage bore and an annular bore, a cover with a central threaded bore, a piston movably mounted in the housing annular bore, a hollow sleeve placed in the housing and the cover rotatably on the rolling bearings, a spherical recess located under a cover, a sealing element located above the end surface of the piston and interacting with a spherical recess, a faceplate located between the piston and the housing, hydraulic the channels for coupling the supra-piston and sub-piston cavities of the annular bore of the housing with a hydraulic actuator, according to the invention is additionally equipped with a flange made with a central passage hole and tightly connected to the cover, a radial sleeve stopper installed in the cover, supporting the upper with the central passage hole, hermetically connected to the upper part the cavity of the liner and containing a spherical recess, a lower support with a central bore, hermetically mounted on the piston end with the possibility of rotation on bearings of rolling and sliding and hermetically interacting with the lower part of the sleeve, while the sealing element is located between the upper and lower bearings and interacts with them.

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