RU2731436C1 - Annular seal test bench - Google Patents

Abstract

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: proposed invention relates to oil and gas industry, in particular, to annular seal test bench. Disclosed annular seal test bench for annular sealing leak testing and installation of annular seal comprises: a cylindrical housing, in the lower part of which a casing suspension simulator is installed; a test cover configured to hermetically close the body during tests and with the possibility of together with the inner surface of the body and the outer surface of the simulator of the casing string suspension of the formation of a test chamber configured to receive a test seal; a mounting cover having a central opening and configured to hermetically close the housing when installing the seal; rod made in the form of a cylinder with variable diameter; system for supply of working and test medium and control of leaks of working and test medium through annular seal.

EFFECT: technical result is reliable check of operating capacity of annular seal at two-stage sealing.

5 cl, 2 dwg

Description

TECHNICAL FIELD OF THE INVENTION

The proposed invention relates to the oil and gas industry. In particular, to the test bench of the annular seal, which is included in the set of test equipment for the system of subsea casing heads and can be used at the stage of acceptance and acceptance tests.

LEVEL OF TECHNOLOGY

From the prior art, constructions are known that make it possible to check the tightness of the annular seal under the action of pressure in the pipe and annular spaces. An annular seal can be used to seal the annulus in a subsea production system under high axial pressure conditions. Typically, an annular seal is a combination of several O-ring components.

The prior art known useful model RU 119828, publ. 08/27/2012, IPC F15B 19/00, G01M 13/00, showing a stand for testing gas-dynamic seals of rotors of natural gas blowers, containing a test chamber in which seals are supposed to be installed, a system for supplying the tested medium and monitoring leaks of the tested medium through the seals. The disadvantages of the known technical solution is the possibility of distorting the test results, since it is not ensured that the seals are correctly installed in the test chamber.

In addition, the prior art is also known source RU2604778, publ. 10.12.2015, IPC F04B 51/00, G01M 3/04, F04D 29/19, opening stand for testing the mechanical seals of circulating pump shafts. The known stand includes a housing containing a pump shaft simulator sleeve for transmitting force to the seal. The disadvantage is also distortion of the test results, since it is not ensured that the seals are installed correctly.

DISCLOSURE OF THE INVENTION

The proposed test bench for annular seal for testing the tightness of the annular seal and installing an annular seal made with the possibility of installation in the space between the casing string and the casing suspension, comprising: an essentially cylindrical body, in the lower part of which is installed a simulator of the casing suspension having a cylindrical inner surface ; a test cover made with the possibility of hermetically closing the casing during testing and with the possibility, together with the inner surface of the casing and the outer surface of the casing suspension simulator, to form a test chamber, made with the possibility of installing a test annular seal therein; a mounting cover having a central opening and configured to seal the housing when the seal is installed; a rod made in the form of a cylinder with a variable diameter, the first diameter corresponding to the diameter of the inner surface of the casing hanger simulator, the second diameter corresponding to the diameter of the inner surface of the body, and the third diameter corresponding to the diameter of the hole in the mounting cover; a system for supplying the working medium and monitoring the leaks of the working and test medium through the annular seal.

The proposed stand may contain an auxiliary cover made with the possibility of forming, together with the mounting cover and the rod, a first sealed functional cavity functioning as a hydraulic cylinder simulating the weight of the drill string.

Preferably, in the proposed stand, the outer surface of the lower part of the shock, the lower surface of the middle part of the stem and the inner surface of the housing are configured to form a second sealed functional cavity.

Preferably in the proposed stand in the middle part of the rod there is a platform, on the upper surface of the middle part of the rod and with the possibility of functioning as a hydraulic cylinder of the tool for installing an annular seal when pressure is applied to the second sealed functional cavity, while it is a flat ring, and the thickness of the ring is the difference between diameters D1 of the lower part of the stem and D3 of the upper part of the stem.

Preferably, in the proposed stand, between the casing and the casing hanger simulator, a sealed additional cavity is formed to simulate the axial force of thermal expansion of the casing string.

The technical result is a reliable check of the strength of fixing the suspension of the siege string relative to the body of the system of subsea casing heads using an annular seal under the action of the forces of thermal expansion of the casing; tightness of the annular seal after the action of a cyclic load from thermal expansion of the casing; operability of the annular seal in a two-stage sealing, in which the first stage of sealing (or pre-sealing) comes from the weight of the drill string, and the second stage of activation comes from the hydraulic system of the tool for installing the annular seal.

In the context of the present description, the words "upper", "lower", "first", "second", etc. are used as adjectives solely to distinguish the nouns to which they refer from each other, and not for the purpose of describing any specific connection between these nouns.

BRIEF DESCRIPTION OF DRAWINGS

For a better understanding of the present invention, as well as its other aspects and characteristics, the description is given with reference to the accompanying drawings, where:

in FIG. 1 schematically shows a stand according to the invention in a position for installing an annular seal;

in FIG. 2 schematically shows a stand according to the invention in a position for testing an annular seal.

CARRYING OUT THE INVENTION

The proposed invention is an annular seal test bench for testing the tightness of the annular seal and installing the annular seal, which is included in the set of test equipment for the system of subsea casing heads and can be used at the stage of acceptance and acceptance tests.

As used herein, seal activation should be understood to mean the process of moving the seal from the initial position in which it is located in the annulus to an operating position at which sealing of the annular space between the casing hanger body and the casing head body is achieved. The deactivation of the seal should be understood as the process of moving the seal from the operating position to its original position. Pre-sealing is understood as the state of the annular seal, in which the force of the weight of the drill string is applied, and the contact pressure arises between the annular seal and the corresponding sealing surfaces of the casing string casing and the casing hanger body, sufficient for the hydraulic system of the tool to set the casing seals. Activation is understood as the process of transition of the annular seal under the action of the force from the tool for setting in a state in which the calculated contact pressure is created between the seal and the counter sealing surfaces of the casing head of the casing string and the casing of the casing.

The annular seal is designed to be installed in the space between the casing string and the casing hanger.

The stand 1 is formed by a body 2, the lower part of which is closed by a casing hanger simulator 3. The body 2 has a substantially cylindrical shape. The casing hanger simulator 3 has a cylindrical inner surface. The inner surface of the casing 2 follows the contours of the inner surface of the casing of the casing head, and the outer surface of the simulator 3 of the casing suspension follows the contours of the outer surface of the casing.

The bench also contains three covers: a mounting cover 4, an auxiliary cover 5 and a test cover 6. The mounting cover 4 and an auxiliary cover 5 are used to install the annular seal 7 in the annular space between the body 2 and the casing hanger simulator 3. FIG. 1 shows the stand 1 in the position for installing the annular seal. In the body 2 of the stand 1 there is a simulator 3 of the casing suspension. In the simulator 3 of the casing suspension, an outlet 8 is made for bleeding air from the closed cavity, and when testing the annular seal 7, a plug 9 is built into the outlet 8 of the simulator 3 of the casing suspension.

To install the annular seal 7 in the annular space between the inner surface of the housing 2 and the simulator 3, the annular seal 7 itself is assembled (since it is usually a combined seal and must be assembled from several ring-shaped parts, the drawings do not show the component parts of the seal) is placed in the housing 2 together with the simulator 3 of the casing suspension. The casing hanger simulator 3 has an inner cylindrical surface 10, into which the rod 11 is then installed. The rod 11 has a variable diameter, namely, the lower part of the rod 11 has a first diameter D1, the middle part of the rod has the largest second diameter D2, and the upper part of the rod has the smallest the third diameter is D3, with D2> D1> D3. The middle portion of the rod 11 is projecting relative to the lower and upper portions of the rod 11, as seen in FIG. 1.

Technological holes 12 are made in the middle part of the rod, passing along the axis and at the same distance from the axis, and necessary for the flow of the working medium when moving the rod 11. In this case, the diameter D1 of the lower part of the rod 11 corresponds to the diameter of the inner part of the simulator 3 of the casing suspension, so that there are no gaps between the middle part of the stem and the inner part of the body 2; additionally, to create tightness, the mating surfaces of the stem 11 and simulator 3 are sealed with seals (not shown in the drawing).

The body 2 is closed with a mounting cover 4, in which a hole 13 is made for the upper part of the stem 11 having a second diameter D3 so that the upper part of the stem 11 protrudes from the hole 12. An auxiliary cover 5 is installed on the mounting cover 4, which is fixed relative to the mounting cover 4 with fastening means 14, which may be bolted connections or other suitable connections. Similar fasteners 14 are used to secure the mounting cover 4 relative to the housing 2 and also to secure the test cover 6 relative to the housing 2.

The auxiliary cover 5 together with the positioning cover 4 and the stem 11 form a sealed functional cavity A, as shown in FIG. 1, made with the possibility of supplying it with a working medium under pressure. The second sealed functional cavity E, made with the possibility of supplying a working medium into it, is formed by the outer walls of the rod 11, the simulator 3 of the casing suspension and the inner walls of the housing 2.

To supply the working medium to the corresponding cavities, channels are provided: the first supply channel 15, the second supply channel 16, the third supply channel 17 and the fourth supply channel 18. The pressure is released, respectively, through the first release channel 19, the second release channel 20, the third release channel 21 and fourth bleed channel 22.

It should be understood that the system for supplying the working fluid and monitoring the leaks of the working fluid through the annular seal includes pumps, pressure gauges and valves, with each supply and bleed channel associated with a combination of a pump, valve and pressure gauge. Thus, for example, the first discharge channel 15 corresponds to the first bleed channel 19, the first pump H1, the first valve B1 and the first pressure gauge M1.

To install the annular seal 7 in the annular space between the housing 2 and the simulator 3, the first functional cavity A is fed by the first pump H1 through the first supply channel 15, the working medium under pressure, while the upper part of the rod 11, which has a third diameter D3, operates. A downward force acts on the upper part of the rod 11, while the middle part of the rod 11, having a second diameter D2, presses on the annular seal 7 and facilitates its installation in the annular space between the body 2 and the simulator 3 of the casing hanger. When the predetermined pressure in the first functional cavity A is reached, the pressure in it is controlled by means of the first manometer M1.

The upper part of the rod 11, together with the installation cover 4 and the auxiliary cover 5, act as a hydraulic cylinder with a working cavity, i.e. the first functional cavity A, simulating the weight of the drill string for pre-installation (or in other words, pre-sealing) of the annular seal 7.

Then, into the second functional cavity E, formed by the outer surface of the lower part of the shock 11, the lower surface of the middle part of the rod 11 and the inner surface of the housing 2, the working medium is fed by means of the second pump H2 under pressure, until the pressure is reached, ensuring the complete installation of the annular seal 7, then shut off the second valve B2 and observe by means of the second manometer M2 whether there is a pressure drop.

The pressure of the working medium and the holding time under pressure can be selected by the person skilled in the art, based on industry standards, taking into account the particular operation of the equipment.

After the delivery of pressure to the functional cavities A and E and ensuring that there are no leaks, the annular seal 7 is considered fully installed (or in other words, sealed) in the annular space between the body 2 and the casing hanger simulator 3.

In the middle part of the rod 11 there is a platform C located on the upper surface of the middle part of the rod 11. When pressure is applied to the second functional cavity E, the platform C simulates the hydraulic cylinder of the annular seal installation tool 7. The platform C is a flat ring, and the thickness of the ring is the difference between diameters D1 and D3.

After that, stand 1 is partially disassembled by removing the auxiliary cover 5, then the mounting cover 4, then removing the rod 11.

FIG. 2 shows stand 1 in position for testing the annular seal.

Further, as shown in FIG. 2, a test cover 6 is installed on the body 2, which hermetically closes the body 2 to form a sealed tubular cavity F.

Then, into the tubular cavity F formed by the inner walls of the casing 2, the surface of the simulator 3 of the casing suspension and the test cover 6, with the annular seal 7 installed in it, the test medium is supplied under pressure through the second pump H2 through the second supply channel 16.

The pressure of the test medium and the holding time under pressure can be selected by the person skilled in the art based on industry standards, taking into account the particular operation of the equipment.

When the desired pressure value in the tube cavity F is reached, the second valve B2 is closed and the pressure value is monitored by means of the second manometer M2: whether there is a decrease in pressure. If there is no pressure drop in the tubular cavity F during the holding time, then the pressure from the tubular cavity F is vented through the second bleed channel 20 and the test medium is supplied by means of the third pump H3 under pressure to the annular cavity G.

Valve B3 is closed in the same way, it is observed whether there is a pressure drop in the annular cavity G using a manometer M3. Then the pressure from the annular cavity G is released through the channel 20. The annular cavity G is formed by the outer surface of the simulator 3, the inner surface of the body 2 and the lower part of the annular seal 7.

Cavities F and G are separated from each other by means of an annular seal 7 and correspond to the pipe and annular spaces of the subsea casing head system. Together, cavities F and G form a test chamber for testing the annular seal, the test chamber is configured to install the tested annular seal therein. The test chamber is formed by a test cover 6 installed on the casing 2, together with the inner surface of the casing 2 and the outer surface of the simulator 3 of the casing suspension. The annular space between the casing 2 and the casing hanger simulator 3 simulates the space in the subsea casing head system for installing the annular seal 7.

When pressure is applied to the tube cavity F, this cavity simulates the effect of pressure from above on the annular seal 7 under real operating conditions.

The supply of pressure to the annular cavity G simulates the effect of pressure from below on the annular seal 7 in real operating conditions.

An additional cavity K is provided between the casing 2 and the casing hanger 3, into which the test fluid is also supplied by the fourth pump H4 through the fourth supply channel 17. When pressure is applied to the additional cavity K, this cavity simulates the axial thermal expansion of the casing. Additional cavity K is necessary to check the strength of the annular seal 7 and for the cyclic life of the components of the annular seal.

The annular seal 7 should be installed with a small play, allowing vertical movement of the annular seal 7, not exceeding the specified value. Therefore, the annular seal 7 can move within this play when loaded from above and below. To control the amount of backlash, the annular seal is provided with fixing parts, for example, crackers (not shown in the drawings): the first fixing part is installed partially in the seal 7 and partially in the inner part of the housing 2, and the second fixing part is installed partially in the seal 7 and partially in the simulator 3 casing hangers.

When the test fluid is supplied under pressure in the G, K cavity, the annular seal can be loaded from below to such an extent that the retaining parts will fail. The downward movement of the annular seal is limited by the simulator 3.

The working and test environment are selected by the person skilled in the art.

It should be understood that the invention is limited only by the scope of the claims. Modifications and improvements to the above-described embodiments of the present invention without departing from the scope of the claims will be apparent to those skilled in the art. The present description is presented by way of example only and does not impose any restrictions on the scope of protection of the invention. Thus, the scope of the present technology is limited only by the scope of the appended claims.

Claims (12)

1. An annular seal test bench for testing the tightness of the annular seal and installing an annular seal designed to be installed in the space between the casing string and the casing hanger, comprising: a substantially cylindrical body, at the bottom of which is mounted a casing hanger simulator having a cylindrical inner surface; a test cover made with the possibility of hermetically closing the casing during testing and with the possibility, together with the inner surface of the casing and the outer surface of the casing suspension simulator, to form a test chamber, made with the possibility of installing a test annular seal therein; a mounting cover having a central opening and configured to seal the housing when the seal is installed; a rod made in the form of a cylinder with a variable diameter, the first diameter corresponding to the diameter of the inner surface of the casing hanger simulator, the second diameter corresponding to the diameter of the inner surface of the body, and the third diameter corresponding to the diameter of the hole in the mounting cover; a system for supplying the working and test medium and monitoring the leaks of the working and test medium through the annular seal. 2. The stand according to claim. 1, comprising an auxiliary cover made with the possibility of forming, together with the mounting cover and the rod, a first sealed functional cavity functioning as a hydraulic cylinder simulating the weight of the drill string. 3. The stand of claim. 1, in which the outer surface of the lower part of the shock, the lower surface of the middle part of the rod and the inner surface of the body are made with the possibility of forming a second sealed functional cavity. 4. The stand according to claim 1, in which in the middle part of the rod there is a platform located on the upper surface of the middle part of the rod and made with the possibility of functioning as a hydraulic cylinder of the tool for installing the annular seal when pressure is applied to the second sealed functional cavity, while the platform is a flat ring, and the ring thickness is the difference between the diameters D1 of the bottom of the stem and D3 of the top of the stem. 5. The stand according to claim 1, in which a sealed additional cavity is formed between the body and the casing hanger simulator to simulate the axial force of thermal expansion of the casing string.

Images