A device for testing the sealing performance of a subsea wellhead head seal assembly

Abstract

A kind of underwater wellhead head sealing assembly sealing test device, including sealing outer shell, sealing upper cover and sealing lower cover are respectively installed on the upper and lower end of sealing outer shell, sealing inner core and metal seal ring that is sleeved on the outside of sealing inner core are equipped in sealing outer shell, two sealing support rings are symmetrically arranged in the upper and lower of metal seal ring, the sealing support ring located in upper portion is equipped with gland between sealing upper cover, sealing upper cover is equipped with pressurized injection hole and center hole, and hollow structure's travel indicating rod is connected with gland by screw thread through center hole;Sealing lower cover is equipped with test injection hole;Sealing outer shell middle part is equipped with outer shell ring groove and outer shell through-flow hole connected with outer shell ring groove.The present application combines two processes of loading sealing and sealing test, facilitates technical personnel to carry out structure optimization;Can be clear about weak position of sealing, according to need to carry out sealing assembly structure improvement;Sealing process can record displacement data and pressure data simultaneously, for subsequent analysis.

Description

TECHNICAL FIELD

[0001] The present application relates to a device for detecting sealing performance, in particular a sealing performance testing device for a subsea wellhead sealing assembly. BACKGROUND

[0002] In order to prevent blowout, deep-sea oil and gas drilling wells are equipped with high-pressure wellheads, and casing hangers are hung in the high-pressure wellheads. A dedicated sealing assembly is needed to seal the gap between the casing hanger and the high-pressure wellhead to ensure the isolation of high-pressure fluid in the well from seawater. The existing sealing assembly device is composed of a metal sealing ring and a sealing drive ring. During installation, the sealing drive ring is pressed against the metal sealing ring under load, causing the sealing ring to deform laterally and contact the inner and outer sides of the annular space, and forming a compression to achieve sealing on both sides of the annular space. Due to the high cost of offshore construction and the high sealing requirements of the sealing assembly, it is essential to test the sealing performance of the sealing assembly before its field application. Sealing performance testing devices have been developed for various sealing structures, including loading test devices and air tightness testing devices. However, there is still a lack of integrated sealing performance testing devices for wellhead sealing assemblies. The existing subsea wellhead sealing assembly testing devices have the following problems: 1. Only a single process is considered, such as sealing or testing air tightness during the loading process; 2. The displacement is not observed during the loading process, which cannot guarantee that the sealing drive ring is pressed into place, and it is not convenient for experimental personnel to analyze the subsequent data; 3. The sealing surface of the sealing assembly is the inner and outer sides of the annular space. During the sealing performance test, it is not possible to determine the failure position, and the sealing assembly structure cannot be modified and improved in a timely manner based on the test results. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings of the prior art and provide a subsea wellhead sealing assembly sealing performance testing device that can simultaneously achieve sealing by loading and pressurization and sealing performance testing.

[0004] The problems described in the present application are achieved by the following technical solutions:

[0005] The utility model provides a kind of underwater wellhead seal assembly tightness test device, including sealed outer shell body, sealed upper cover and sealed lower cover are respectively installed on the upper and lower ends of sealed outer shell body, sealing inner core and metal seal ring that are sleeved in the outer side of sealing inner core are equipped in sealed outer shell body, two sealing support rings are symmetrically arranged in the upper and lower of metal seal ring, the sealing support ring located in upper portion is equipped with gland between sealing upper cover, sealing upper cover is equipped with pressurized injection hole and central hole, the travel indicating rod of hollow structure is connected with gland by screw thread through central hole;Sealed lower cover is equipped with test injection hole;Sealed outer shell body middle part is equipped with outer shell body ring groove and the through-flow hole of connecting outer shell body ring groove;By test injection hole, the flow channel of inner sealing surface test between sealing inner core and metal seal ring and indicating rod, by test injection hole, the flow channel of outer sealing surface test between metal seal ring and sealed outer shell body, outer shell body ring groove and outer shell body through-flow hole.

[0006] The above-mentioned underwater wellhead seal assembly tightness test device, the metal seal ring is equipped with upper and lower limit ring grooves, the one end of the sealing support ring corresponding to the metal seal ring is respectively matched and inserted into the upper and lower limit ring grooves, the one end of the sealing support ring corresponding to the metal seal ring is uniformly distributed through pressure hole, the through pressure hole is T-shaped, and the horizontal section of the through pressure hole penetrates the wall of the sealing support ring.

[0007] The above-mentioned underwater wellhead seal assembly tightness test device, the contact part of the outer wall of the sealing inner core and the metal seal ring is equipped with an inner core simulated material cladding layer, and the contact part of the sealed outer shell body and the metal seal ring is equipped with an outer shell body simulated material cladding layer.

[0008] The above-mentioned underwater wellhead seal assembly tightness test device, a gap is left between the sealing upper cover and the gland, and a gasket is arranged at the gap during the sealing test.

[0009] The above-mentioned underwater wellhead seal assembly tightness test device, a displacement sensor is arranged on the upper part of the travel test rod.

[0010] The above-mentioned underwater wellhead seal assembly tightness test device, the upper and lower end surfaces of the sealing inner core are respectively equipped with inner core through-flow grooves, and the inner core through-flow grooves are cross-shaped.

[0011] The above-mentioned underwater wellhead seal assembly tightness test device, the end surface of the sealing lower cover corresponding to the sealing inner core is equipped with a central buffer groove, and the periphery of the central buffer groove is equipped with a sealing lower cover through-flow groove.

[0012] The above-mentioned underwater wellhead seal assembly tightness test device, the thickness of the inner core simulated material cladding layer is not less than 5 mm, and the thickness of the outer shell body simulated material cladding layer is not less than 5 mm.

[0013] The above-mentioned underwater wellhead seal assembly tightness test device, the travel indicating rod is matched with the seal gap, a seal ring is arranged between the travel indicating rod and the sealing upper cover, and a seal ring is arranged between the travel indicating rod and the gland.

[0014] The sealing assembly for underwater wellhead is characterized in that a sealing ring is arranged between the gland and the sealing outer shell body, and a sealing ring is arranged between the end surface of the gland and the end surface of the sealing support ring located at the upper portion.

[0015] Compared with the prior art, the present application has the following advantages: 1. The whole working process requirements of the sealing assembly are comprehensively considered, and the two processes of loading sealing and sealing testing are combined, so that the structure optimization of the technical personnel is facilitated; 2. When the inner sealing surface fails during the sealing testing, the high-pressure fluid will flow out from the internal passage of the stroke indicating rod, and when the outer sealing surface fails, the high-pressure fluid will flow out from the sidewall surface of the wellhead, so that the relatively weak position of the sealing can be determined, and the structure of the sealing assembly can be improved according to the requirements; 3. The displacement data and the pressure data can be recorded simultaneously during the sealing process, which can be used for subsequent analysis; 4. The structure design is reasonable, the function is complete, the installation is convenient, and the sealing assembly can be reused. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic view of the present application Figure 2 is an A-A sectional view of the present application

[0017] Figure 2 is a top view of the present application

[0018] Figure 3 is a top view of the sealing inner core

[0019] Figure 4 is a B-B sectional view of the present application Figure 3

[0020] Figure 5 is a bottom view of the present application Figure 4

[0021] Figure 6 is a sectional view of the sealing outer shell body

[0022] Figure 7 is a structural schematic view of the sealing lower cover

[0023] Figure 8 is a C-C sectional view of the present application Figure 7

[0024] Figure 9 is a structural schematic view of the sealing support ring

[0025] Figure 10 is a D-D sectional view of the present application Figure 9

[0026] ​​​​The list of reference numerals in the figure is: 1, stroke indicating rod, 2, sealing upper cover, 2-1, pressurized liquid injection hole, 3, gasket, 4, gland, 5, sealing support ring, 5-1, pressure passage hole, 6, sealing outer shell, 6-1, outer shell simulated material cladding layer, 6-2, outer shell ring groove, 6-3, outer shell flow passage, 7, metal sealing ring, 8, sealing inner core, 8-1, inner core simulated material cladding layer, 8-2, inner core flow groove, 9, sealing lower cover, 9-1, test liquid injection hole, 9-2, sealing lower cover flow groove, 9-3, center buffer groove, 10, displacement sensor. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with reference to the accompanying drawings. It should be noted that the specific implementation is only used to explain the present application, and is not used to limit the present application.

[0028] Referring to Figure 1 , Figure 2 , the device described in the present application can complete loading sealing and sealing performance testing, and the two functions are combined into one. The device includes a sealing outer shell 6 for simulating the cylindrical shape of the wellhead, a sealing inner core 8 for simulating the cylindrical shape of the casing, and also includes a gland 4, a sealing upper cover 2, a sealing lower cover 9, a metal sealing ring 7, and a sealing support ring 5. The sealing upper cover is bolted to the upper end of the sealing outer shell, and the sealing upper cover is provided with a pressurized liquid injection hole 2-1. The sealing lower cover is bolted to the lower end of the sealing outer shell, and the sealing lower cover is provided with a test liquid injection hole 9-1. The sealing inner core and the metal sealing ring 7 sleeved outside the sealing inner core are arranged in the sealing outer shell, and the metal sealing ring is symmetrically provided with a sealing support ring above and below. The gland is located between the upper sealing support ring and the sealing upper cover, and a gap is left between the sealing upper cover and the gland. A gasket 3 is arranged in the gap during sealing test. The sealing upper cover is also provided with a center hole, and a stroke indicating rod 1 is installed in the center hole. The stroke indicating rod is hollow, the lower part of the stroke indicating rod is threadedly connected with the gland, and the upper part of the stroke indicating rod is provided with a displacement sensor 10. The stroke indicating rod is gap-fitted with the sealing upper cover, a sealing ring is arranged between the stroke indicating rod and the sealing upper cover, a sealing ring is arranged between the stroke indicating rod and the gland, a sealing ring is arranged between the gland and the sealing outer shell, and a sealing ring is arranged between the end face of the gland and the end face of the upper sealing support ring. The sealing support ring is gap-fitted with the sealing outer shell.

[0029] Referring to Figures 3-5 , in order to obtain the most actual state test effect, the inner core simulated material cladding layer 8-1 is arranged at the contact position between the outer wall of the sealing inner core 8 and the metal sealing ring. The inner core simulated material cladding layer is selected from the same material as the casing, and the thickness of the inner core simulated material cladding layer is not less than 5 mm. The upper and lower end faces of the sealing inner core are respectively provided with inner core flow grooves 8-2, and the inner core flow grooves are cross-shaped.

[0030] Referring to Figure 6 The middle part of the sealing outer shell 6 is provided with an outer shell ring groove 6-2 and an outer shell through-flow hole 6-3 connected with the outer shell ring groove, and the outer shell ring groove and the outer shell through-flow hole are used for flowing fluid to detect whether there is leakage between the metal sealing ring and the sealing outer shell. In order to obtain the most actual test effect, the sealing outer shell and the metal sealing ring contact part is provided with an outer shell simulated material cladding layer 6-1, the outer shell simulated material cladding layer is selected from the same material as the wellhead, and the thickness of the outer shell simulated material cladding layer is not less than 5 mm.

[0031] Referring to Figure 7 , Figure 8 The sealing lower cover is provided with a center buffer groove 9-3 on the end face corresponding to the sealing inner core, and the center buffer groove is corresponding to the sealing inner core; the sealing lower cover is provided with a sealing lower cover through-flow groove 9-2 around the center buffer groove, and the sealing lower cover through-flow groove is evenly distributed in four parts, and the sealing lower cover through-flow groove is corresponding to the lower end face of the sealing support ring located on the upper part.

[0032] Referring to Figure 1 , Figure 9 , Figure 10 The metal sealing ring is provided with upper and lower limiting ring grooves, and one end of the sealing support ring corresponding to the metal sealing ring is respectively matched and inserted into the upper and lower limiting ring grooves. The one end of the sealing support ring corresponding to the metal sealing ring is evenly distributed with a through-pressure hole 5-1 capable of avoiding pressure retention, and the through-pressure hole is in T shape, and the transverse section of the through-pressure hole penetrates the outer wall of the sealing support ring.

[0033] Referring to Figure 1 The working process of the present application is as follows:

[0034] 1. The whole working process includes two parts of loading sealing and carrying out sealing test. In the loading sealing stage, the tester can carry out the sealing process in the air environment according to the needs, or can immerse the device in the pool to carry out the pool test and complete the sealing.

[0035] In the initial installation state, the sealing is not completed, and the two sealing support rings are only in contact with the metal sealing ring and are not deformed by extrusion. There is a gap between the gland and the sealing upper cover, and the gap is the pressure loading position. The fluid is injected into the high-pressure fluid through the pressurized liquid injection hole of the sealing upper cover, and the gap is filled, and then the gland is driven to slide downward, the upper sealing support ring is extruded and moves downward, the lower sealing support ring is limited by the sealing lower cover and cannot move, the metal sealing ring is extruded and forced to deform on both sides, and as the pressure increases, the distance of the downward movement of the upper sealing support ring gradually increases, and when the maximum displacement is reached, the metal sealing ring reaches the maximum deformation and forms a seal with the sealing outer shell and the sealing inner core. At the same time, when the gland moves downward, the travel indicator rod is driven to move, and the displacement of the travel indicator rod can be read through the displacement sensor, so as to ensure that the gland and the driving ring have moved to the maximum displacement and the sealing is completed.

[0036] Fluid flow inside the loading and sealing process device:

[0037] (1) First, the fluid is injected into the space between the sealing upper cover and the pressure cover through the pressure pump through the pressure injection hole of the sealing upper cover. During the pressurization process of the pressure pump, the fluid pressure in the space increases, which plays the role of pressurizing the pressure cover and moving it downward.

[0038] (2) When the gland slides downward, the fluid originally existing between the gland and the top of the sealing core can flow out through the central flow channel of the stroke indicator rod, preventing pressure from being trapped here and preventing the gland from moving downward.

[0039] (3) When the metal sealing ring is squeezed and deformed and the sealing is not completed, the original fluid between the metal sealing ring and the sealing inner core and the sealing outer shell will squeeze out part of the fluid upward and downward.

[0040] (4) A pressure-releasing hole is provided at one end of the sealing support ring, and a housing ring groove and a housing flow-through hole are provided at the sealing housing. During the squeezing process between the upper sealing support ring and the upper limiting ring groove of the metal sealing ring, the fluid in the limiting ring groove can flow out through the pressure-releasing hole, and then flow out of the housing through the housing groove and the housing flow-through hole, thereby preventing the problem of fluid pressure buildup in the upper limiting ring groove of the metal sealing ring, which results in failure to seal.

[0041] (5) The contact surface between the sealing lower cover and the sealing support ring is provided with a sealing lower cover flow groove, and the end surface of the sealing inner core is provided with a sealing inner core flow groove. During the extrusion process between the lower sealing support ring and the lower limiting ring groove of the metal sealing ring, the fluid in the lower limiting ring groove of the metal sealing ring can flow out through the pressure-releasing hole of the lower sealing support ring, and then flow out through the sealing cover flow groove, the sealing inner core flow groove, and the test injection hole outflow device. This prevents the problem of fluid pressure buildup in the groove of the lower limiting ring groove of the metal sealing ring, resulting in failure to seal.

[0042] 2. After loading and sealing, unload the upper hydraulic pressure. The sealing ring will not move and the sealing will continue. Open the sealing cover, increase the gap between the sealing cover and the gland, and add a gasket to the gap to ensure that the gland, gasket, and sealing cover are tightly stacked. The purpose is to ensure that the gland does not slip during the subsequent sealing test. After the gasket and sealing cover are installed, perform a sealing test.

[0043] 3. The lower sealing cover has a test liquid injection hole for reverse sealing test. The inner core of the simulated casing hanger has inner core flow-through grooves on the upper and lower end faces. When high-pressure fluid enters the device through the lower sealing cover, the high-pressure fluid will squeeze the sealing surfaces on the inner and outer sides of the metal sealing ring. When the sealing surface between the metal sealing ring and the sealing inner core fails, the fluid will pass through this location, then flow through the inner flow-through groove at the top of the sealing inner core and the hollow channel of the travel indicator rod, and flow out of the device, proving that the inner sealing has failed. When the sealing surface between the metal sealing ring and the sealing outer shell fails, the fluid will pass through the failure location, the outer shell groove, and the outer shell flow-through hole to flow out of the outer shell and out of the device, proving that the outer sealing surface has failed. The above process can identify the relatively weak position of the sealing of the device, and the structure is optimized according to whether it meets the working requirements.

Claims

1. A device for testing the sealing performance of an underwater wellhead seal assembly, comprising a sealing outer shell, an upper sealing cover and a lower sealing cover mounted on the upper and lower ends of the sealing outer shell, a sealing inner core and a metal sealing ring sleeved on the outer side of the sealing inner core, characterized in that: Two sealing support rings are symmetrically arranged above and below the metal sealing ring. A pressure cap is provided between the upper sealing support ring and the sealing upper cover. The sealing upper cover is provided with a pressurized liquid injection hole and a center hole. A hollow stroke indicator rod passes through the center hole and is threadedly connected to the pressure cap. The sealing lower cover is provided with a test liquid injection hole. The middle of the sealing outer shell is provided with an outer shell annular groove and an outer shell flow hole connected to the outer shell annular groove. The inner sealing surface test flow channel is formed by the test liquid injection hole, the space between the sealing inner core and the metal sealing ring, and the stroke indicator rod. The outer sealing surface test flow channel is formed by the test liquid injection hole, the space between the metal sealing ring and the sealing outer shell, the outer shell annular groove, and the outer shell flow hole. The metal sealing ring is provided with upper and lower limit ring grooves. The end of the sealing support ring corresponding to the metal sealing ring is respectively matched and inserted into the upper and lower limit ring grooves. The end of the sealing support ring corresponding to the metal sealing ring is evenly distributed with pressure holes. The pressure holes are T-shaped, and the transverse sections of the pressure holes pass through the sealing support ring wall. The contact area between the outer wall of the sealing inner core and the metal sealing ring is provided with a surfacing layer of the inner core simulation material, and the contact area between the sealing outer shell and the metal sealing ring is provided with a surfacing layer of the outer shell simulation material; A displacement sensor is provided on the upper part of the travel indicator rod; The upper and lower end surfaces of the sealing inner core are respectively provided with inner core flow grooves, and the inner core flow grooves are cross-shaped; The sealing lower cover is provided with a central buffer groove on the end surface corresponding to the sealing inner core, and a sealing lower cover through-flow groove is provided around the central buffer groove.

2. The underwater wellhead sealing assembly sealing test device according to claim 1, characterized in that: A gap is left between the sealing upper cover and the pressure cover, and a gasket is set in the gap during the sealing test stage.

3. The underwater wellhead sealing assembly sealing test device according to claim 1, characterized in that: The thickness of the surfacing layer of the inner core simulation material shall not be less than 5mm, and the thickness of the surfacing layer of the outer shell simulation material shall not be less than 5mm.

4. The underwater wellhead sealing assembly sealing test device according to claim 1, characterized in that: The stroke indicating rod is matched with the sealing upper cover in a clearance, a sealing ring is provided between the stroke indicating rod and the sealing upper cover, and a sealing ring is provided between the stroke indicating rod and the pressure cover.

5. The underwater wellhead sealing assembly sealing test device according to claim 1, characterized in that: A sealing ring is provided between the gland and the sealing outer shell, and a sealing ring is provided between the end face of the gland and the end face of the sealing support ring located at the upper part.

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