A method for analyzing a seal leakage of a subsea wellhead connector

Abstract

The present application relates to a kind of underwater wellhead connector sealing leakage analysis method, method includes: obtaining the surface topography of metal sealing ring in underwater wellhead connector;The surface topography of metal sealing ring is carried out multi-scale decomposition and characterization, obtains the surface component of different scales of metal sealing ring;Underwater wellhead connector metal sealing multi-scale contact model is established, the contact behavior of the surface component of different scales of metal sealing ring and the influence on sealing performance are analyzed;Underwater wellhead connector sealing contact surface grid leakage model is established, the sealing-leakage state of sealing interface and its change rule are analyzed;Based on the sealing contact surface grid leakage model of underwater wellhead connector, the calculation equation of forming leakage channel is solved, and the leakage rate prediction method considering surface roughness and surface sealing gap height is deduced;Based on the leakage rate prediction method, relevant experimental research is carried out to verify the theoretical model and numerical result, and experimental verification and basis are provided for the application of underwater wellhead connector.

Description

TECHNICAL FIELD

[0001] The application relates to a method for analyzing sealing leakage of a subsea wellhead connector and belongs to the technical field of offshore oil production. BACKGROUND

[0002] The subsea wellhead connector is one of key equipments for deep-sea oil and gas production, has the functions of connecting a subsea wellhead and a Christmas tree, preventing high-temperature and high-pressure oil and gas leakage in a well, supporting a metal sealing ring and bearing various complex loads, and the sealing problem thereof is related to the safe production of offshore oil and gas.

[0003] The complex geometry and multi-scale nature of the rough surface of the metal sealing ring of the subsea wellhead connector bring great difficulties to the theoretical analysis of the sealing performance. At present, the mapping relationship between the sealing performance of the subsea wellhead connector and the surface morphology of the metal sealing ring has not been constructed from the theoretical aspect, so that the sealing contact characteristics and the leakage mechanism of the subsea wellhead connector are not thoroughly studied. SUMMARY

[0004] In view of the above technical problems, the application provides a method for analyzing sealing leakage of a subsea wellhead connector, which can establish the mapping relationship between the sealing performance and the surface morphology, explore the leakage nature of the sealing interface of the subsea wellhead connector and develop a leakage rate prediction method considering the surface roughness and the height of the surface sealing gap, so as to provide a theoretical basis for the design of the sealing surface of the subsea wellhead connector.

[0005] To achieve the above object, the application adopts the following technical scheme:

[0006] A method for analyzing sealing leakage of a subsea wellhead connector, comprising:

[0007] obtaining the surface morphology of a metal sealing ring in the subsea wellhead connector;

[0008] carrying out multi-scale decomposition and characterization on the surface morphology of the metal sealing ring based on a wavelet transform method to obtain different scale surface components of the metal sealing ring;

[0009] establishing a multi-scale contact model of the metal sealing of the subsea wellhead connector to analyze the contact behavior of the different scale surface components of the metal sealing ring and the influence of the contact behavior on the sealing performance;

[0010] based on percolation theory, establishing a grid leakage model of the sealing contact surface of the subsea wellhead connector to analyze the sealing-leakage state of the sealing interface and the change law thereof;

[0011] based on the grid leakage model of the sealing contact surface of the subsea wellhead connector, solving the Navier-Stokes equation of the leakage channel to obtain a theoretical expression of the leakage rate;

[0012] Based on the theoretical expression of leakage rate and the contact behavior of different scale surface components of the metal sealing ring and the influence on the sealing performance, the related experimental research is carried out to verify the theoretical model and the numerical result, and to provide the experimental verification and basis for the application of the underwater wellhead connector.

[0013] The sealing leakage analysis method of the underwater wellhead connector, preferably, the multi-scale contact model of the metal sealing of the underwater wellhead connector is established based on the following assumptions:

[0014] The underwater wellhead connector is regarded as a smooth rigid plane, and the metal sealing ring is regarded as a rough asperity, and the sealing contact is assumed as the contact between a rigid smooth plane and a spherical ball, and the multi-scale contact model of the metal sealing of the underwater wellhead connector is established.

[0015] The sealing leakage analysis method of the underwater wellhead connector, preferably, the contact behavior of different scale surface components of the metal sealing ring and the influence on the sealing performance are analyzed, and the specific process is as follows:

[0016] Based on the Hertz contact theory, the contact behavior of the metal sealing ring is analyzed, and the theoretical relationship between the deformation, the contact area and the contact load of the metal sealing ring in the elastic region and the plastic region is derived.

[0017] The sealing leakage analysis method of the underwater wellhead connector, preferably, in order to further analyze the contact behavior of the surface of each scale component of the measured metal sealing ring of the underwater wellhead connector, the contact model of each scale of the measured sealing ring surface is established based on the finite element method, the bottom-up modeling method is adopted, the three-dimensional surface data obtained by decomposition is geometrically modeled, the contact of the rough surface is equivalent to the contact between a rough surface and an ideal rigid plane, the multi-scale characteristics and the characterization parameters of the sealing contact surface are used to analyze the contact characteristics of each scale and the influence between scales, the relationship and variation law between the contact stress and different roughness, materials, loads and temperatures are analyzed, the contact behavior of different scale surface components is revealed, the influence of different scale components on the sealing performance is explored, the mapping between the sealing performance of the underwater wellhead connector and the surface topography of the metal sealing ring is established, and thus the purpose of inversely regulating the surface topography of the metal sealing ring according to the sealing performance requirement is achieved.

[0018] The sealing leakage analysis method of the underwater wellhead connector, preferably, based on the percolation theory, the grid leakage model of the sealing contact surface of the underwater wellhead connector is established, and the specific process is as follows:

[0019] A rectangular area on the sealing contact interface of the underwater wellhead connector is extracted as the research object, namely the contact area. The contact area is discretized into a rectangular grid, and the actual contact area is "occupied" by the black grid. The process of sealing interface contact is the process of the grid being "occupied". A is defined as the actual contact area and A0 is defined as the theoretical contact area. The actual contact area is a characteristic quantity that changes with the preload, so the dimensionless contact area ratio A / A0 is used as the control parameter of the grid property.

[0020] The underwater wellhead connector seal leakage analysis method preferably explores the seal-leakage state of the sealing interface and its changing pattern. The specific process is as follows:

[0021] The path-finding algorithm is used to simulate the flow process of the fluid medium at the sealing interface. The mathematical expression of the state evolution curve is obtained by fitting the cumulative distribution function. Based on the previously analyzed contact area and the influence rules including contact load, material, and roughness, the influence of the contact area on the sealing-leakage state evolution characteristics of the sealing interface is analyzed, and the leakage law of the sealing interface of the underwater wellhead connector is explored.

[0022] The underwater wellhead connector seal leakage analysis method preferably obtains a theoretical expression for the leakage rate by solving the Navier-Stokes equation that forms a straight leakage channel in order to further accurately calculate the seal leakage rate; based on the theoretical expression for the leakage rate, relevant experimental research is carried out to verify the theoretical model and numerical results, providing experimental verification and basis for the application of underwater wellhead connectors.

[0023] A second aspect of the present invention provides an underwater wellhead connector seal leakage analysis device, comprising:

[0024] The first processing unit is used to obtain the surface morphology of the metal sealing ring in the underwater wellhead connector;

[0025] The second processing unit is used to perform multi-scale decomposition and characterization of the surface morphology of the metal sealing ring based on the wavelet transform method to obtain surface components of the metal sealing ring at different scales;

[0026] The third processing unit is used to establish a multi-scale contact model of the metal seal of the underwater wellhead connector to analyze the contact behavior of the surface components of the metal seal ring at different scales and their impact on the sealing performance;

[0027] The fourth processing unit is used to establish a grid leakage model of the sealing contact surface of the underwater wellhead connector based on the percolation theory, and analyze the sealing-leakage state and its changing law of the sealing interface;

[0028] a fifth processing unit, configured to solve the Navier-Stokes equations for forming leakage channels based on a grid leakage model of a sealing contact surface of an underwater wellhead connector, and obtain a theoretical expression for a leakage rate;

[0029] The sixth processing unit is used for carrying out relevant experimental research to verify the theoretical model and the numerical result based on the theoretical expression of the leakage rate and the contact behavior of different scale surface components of the metal sealing ring and the influence on the sealing performance, and providing experimental verification and basis for the application of the underwater wellhead connector.

[0030] The third aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the sealing leakage analysis method of the underwater wellhead connector.

[0031] The fourth aspect of the present application provides a computer device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor realizes the steps of the sealing leakage analysis method of the underwater wellhead connector when executing the computer program.

[0032] The present application has the following advantages due to the above technical solutions:

[0033] The present application starts from the surface morphology of the metal sealing ring of the underwater wellhead connector, first, the surface morphology of the contact surface of the metal sealing ring is decomposed and characterized based on the wavelet transform method, a multi-scale contact model of the metal sealing ring of the underwater wellhead connector is established, and the contact behavior of different scale surface components of the sealing ring and the influence mechanism on the sealing performance are explored; then, based on the percolation theory, a grid leakage model of the sealing contact surface of the underwater wellhead connector is established, and the sealing-leakage state of the sealing interface and its change rule are revealed; secondly, the Navier-Stokes equation of the leakage channel is solved, and the leakage rate prediction method considering the surface roughness and the surface sealing gap height is derived; finally, the theoretical model and the numerical result are verified by carrying out relevant experimental research. The implementation of the present application will enrich and perfect the sealing theory of the underwater wellhead connector, and provide scientific support for the application of the underwater wellhead connector. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The connection schematic diagram of the underwater wellhead connector, the wellhead and the tree body of an embodiment of the present application is provided;

[0035] Figure 2 The flow chart of the sealing leakage analysis method of the underwater wellhead connector of the embodiment of the present application is provided;

[0036] Figure 3 The micro contact model diagram of the underwater wellhead connector of the embodiment of the present application is provided;

[0037] Figure 4Graphs showing the leakage model of the sealing contact grid of the underwater wellhead connector provided in this embodiment of the present invention, wherein A / A0 in (a) is 0.8, A / A0 in (b) is 0.55, and A / A0 in (c) is 0.4.

[0038] Figure 5 A diagram showing a leakage channel model of an underwater wellhead connector provided in this embodiment of the present invention;

[0039] Figure 6 for Figure 5 Side view of;

[0040] The reference numerals are as follows:

[0041] 1-Indicating mechanism; 2-Christmas tree body; 3-Metal sealing ring; 4-Locking block; 5-Wellhead connector body; 6-Drive piston; 7-Secondary unlocking piston; 8-Action ring; 9-Wellhead head. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by ordinary persons in this field based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0043] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second", "third", "fourth" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0044] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside," "outside," "inner side," "outer side," "lower," "upper," etc. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0045] One of the prior arts discloses a rubber structure sealing analysis method, which mainly develops secondary computer simulation software, including creating a finite element model of rubber structure; defining rubber structure material properties; defining rubber structure contact; defining result output; defining boundary and working condition; submitting solver calculation; automatic result post-processing. Through secondary development of general CAE software, the structure sealing analysis process is realized. The scheme has the following disadvantages: the surface roughness of rubber parts has significant difference, so when calculating the sealing condition of rubber structure by using ideal model, the influence of contact interface surface roughness amplitude on the leakage of sealing part is ignored. The calculation process does not consider the influence of contact interface surface roughness amplitude on the leakage of sealing part.

[0046] The second prior art discloses a method for modeling the degradation of the sealing performance of an underwater connector, which uses sealing contact strength as a performance indicator, builds a thermal-solid finite element analysis model of the connector sealing performance, and analyzes the sealing performance at the initial time. They also predict the corrosion rate of each part of the connector under actual working conditions, and update the model parameters to calculate the sealing performance at subsequent times. By repeating this process, they obtain the sealing performance indicators at different time points. Finally, they use the Gamma random process to describe the degradation of the sealing performance, and estimate the characteristic parameters of the process, thereby establishing a connector sealing performance degradation model based on the Gamma process. The scheme has the following disadvantages: the degradation of sealing performance may have serious consequences. The invention proposes a random model modeling method for the degradation of the sealing performance of an underwater connector, which is a model for analyzing the degradation of sealing performance from a macroscopic perspective. However, if we look at it from a microscopic perspective, the topographic features of the sealing part, including surface roughness, geometry, and material properties, will directly affect its performance during use, and thus have a significant impact on the sealing effect, durability, and reliability of the sealing part.

[0047] The prior art three discloses an innovative method and system for reliability analysis of underwater connectors, the core features of which are summarized as follows: first, by accurately capturing the actual three-dimensional form of the underwater connector to be tested, a corresponding finite element simulation model is constructed; then, the input parameters and potential failure modes of the model are analyzed in depth, and by referring to common failure cases of similar mechanical equipment, the key vulnerable areas in the underwater connector to be tested are accurately identified; further, according to the identification results, a detailed finite element analysis input strategy is formulated, and the stress and strain distribution of the connector is simulated and calculated; then, for each vulnerable area, a dedicated reliability evaluation model is constructed, and by sampling analysis of the input scheme, the reliability indicators and failure probabilities of these areas are scientifically calculated. The scheme has the following disadvantages: the results of the simulation analysis are largely dependent on the accuracy of the finite element model, and if the model has deviations, the analysis results will also be affected; at the same time, a large number of Monte Carlo simulations require high computing resources, which may require high-performance computer hardware support. Implementing this method requires a deep understanding of finite element analysis and Monte Carlo analysis, and the professional knowledge requirements for the operator are high, and the interpretation of the simulation results may require professional knowledge, which may be difficult for non-professionals to understand.

[0048] The rough surface of the metal sealing ring of the underwater wellhead connector has complex geometry and multi-scale nature, which brings great difficulty to the theoretical analysis of the sealing performance. At present, the mapping relationship between the sealing performance of the underwater wellhead connector and the surface topography of the metal sealing ring has not been constructed from the theoretical aspect, resulting in that the sealing contact characteristics and leakage mechanism of the underwater wellhead connector are not thoroughly studied.

[0049] Based on the above technical problems, the present application provides a method for analyzing the sealing and leakage of an underwater wellhead connector. The two key problems that restrict the understanding of the deep-sea underwater wellhead connector are solved: one is what are the sealing contact characteristics of the underwater wellhead connector under service conditions; the other is how to judge the sealing-leakage state of the contact interface of the underwater wellhead connector and its evolution law.

[0050] As Figure 1As shown, the underwater wellhead connector sealing leakage analysis method provided by the present application is based on the metal sealing structure of the underwater wellhead connector, which comprises: an acting ring 8 sleeved on the wellhead 9, the acting ring 8 comprising a coaxial first acting ring and a second acting ring, the outer diameter of the second acting ring being smaller than that of the first acting ring; a wellhead connector body 5, the wellhead connector body 5 being provided with a trumpet-shaped containing cavity penetrating through the axial direction thereof, the small-diameter end of the containing cavity being connected with the Christmas tree body 2 through a flange, and the large-diameter end of the containing cavity being used for containing the acting ring 8, the first acting ring being connected with the inner wall of the wellhead connector body 5, and a gap being left between the second acting ring and the inner wall of the wellhead connector body 5; a secondary unlocking piston 7 and a driving piston 6, both of which are sleeved on the second acting ring, located in the gap and connected with the inner wall of the wellhead connector body 5, and the driving piston 6 being located above the secondary unlocking piston 7; a lock block 4 sleeved on the wellhead 9 and connected with the lower end surface of the Christmas tree body 2, the lock block 4 being provided with teeth meshing with the tooth grooves of the wellhead 9, and the outer wall surface of the lock block 4 being in contact with the upper end inner wall surface of the driving piston 6; and a metal sealing ring 3 assembled on the top of the wellhead 9 and located in the cavity of the Christmas tree body 2, used for sealing the wellhead 9 and the Christmas tree body 2.

[0051] As shown in the drawings, Figure 2 The underwater wellhead connector sealing leakage analysis method of the present application comprises the following specific steps:

[0052] S1: obtaining the surface morphology of the metal sealing ring in the underwater wellhead connector;

[0053] S2: performing multi-scale decomposition and characterization on the surface morphology of the metal sealing ring based on the wavelet transform method to obtain different scale surface components of the metal sealing ring;

[0054] S3: establishing a multi-scale contact model of the metal sealing of the underwater wellhead connector to analyze the contact behavior of the different scale surface components of the metal sealing ring and the influence on the sealing performance;

[0055] S4: based on the percolation theory, establishing a sealing contact surface grid leakage model of the underwater wellhead connector to analyze the sealing-leakage state of the sealing interface and its change rule;

[0056] S5: based on the sealing contact surface grid leakage model of the underwater wellhead connector, solving the Navier-Stokes equation of the leakage channel to obtain the theoretical expression of the leakage rate;

[0057] S6: based on the theoretical expression of the leakage rate, carrying out relevant experimental research to verify the theoretical model and numerical results, and providing experimental verification and basis for the application of the underwater wellhead connector.

[0058] Specifically, the optical 3D surface profiler is used to measure the underwater wellhead connector metal sealing ring sample, and the obtained three-dimensional data of the real rough surface. Since the rough surface data reflects the three-dimensional topographic features, the low-frequency signal is decomposed into low-frequency components and high-frequency components based on the wavelet transform method, and the following is obtained:

[0059] A j-1 (x1,x2)=A j (x1,x2)+D j (x1,x2) (1)

[0060] where scale j=1~N, A j is the low-frequency coefficient; D j is the high-frequency coefficient; x1 and x2 are two adjacent data points.

[0061] A0(x1,x2) is the measured surface data of the underwater wellhead connector metal sealing ring; A N (x1,x2) is the approximate signal of the Nth level; D N (x1,x2)…D1(x1,x2) is the detail signal of different levels; the two-dimensional signal is decomposed into:

[0062] f(x1,x2)=A0(x1,x2)=A N (x1,x2)+D N (x1,x2)+D N-1 (x1,x2)+…+D1(x1,x2) (2)

[0063] The high-frequency signal is composed of horizontal high-frequency coefficients D j (h) , vertical high-frequency coefficients D j (v) , and diagonal high-frequency coefficients D j (d) :

[0064] D j (x1,x2)=D j (h) (x1,x2)+D j (v) (x1,x2)+D j (d) (x1,x2) (3)

[0065] Through amplitude-frequency characteristic and phase-frequency characteristic analysis, the performance of various wavelet filters is compared, and appropriate wavelet is selected to realize multi-scale decomposition and reconstruction of three-dimensional surface. Through multi-scale filter decomposition, the surface signal is decomposed into N levels (N>1), and the logical relationship of the decomposed signal is shown in formula (4), A N represents the approximate signal of the Nth level, and DN They represent the detail signals of the Nth level respectively.

[0066]

[0067] In order to apply the multi-scale decomposition results of the surface of the metal sealing ring of the underwater wellhead connector to practical engineering problems, the relationship between the wavelet scale and the surface physical scale is established as follows:

[0068]

[0069] Where △L is the sampling interval of the measurement surface, F c is the center frequency of the wavelet, F s and D s Substitute for the pseudo-frequency and pseudo-period of the surface detail signal at the s-scale.

[0070] Based on the sampling theorem, the surface data obtained by multi-scale decomposition of the measured rough surface of the metal sealing ring of the underwater wellhead connector are sampled so that the surface features of this scale can be fully included in the deterministic model. Using the APDL parametric modeling language in ANSYS and a bottom-up modeling approach, the three-dimensional surface data obtained by decomposition are used to construct a geometric model, and a geometric contact model of rough surfaces of different scales is established.

[0071] like Figure 3 As shown in the figure, the underwater wellhead connector is regarded as a smooth rigid plane, the metal sealing ring is regarded as a rough micro-convex body, and the sealing contact is assumed to be the contact between a rigid smooth plane and a sphere. A microscopic contact model of the metal seal of the underwater wellhead connector is established, and the contact behavior of the metal sealing ring is analyzed based on the Hertz contact theory. The theoretical relationship between the deformation, contact area, and contact load of the metal sealing ring in the elastic and plastic regions is derived (known).

[0072] In order to further analyze the contact behavior of the metal sealing ring of the underwater wellhead connector at various scales, a contact model of the measured sealing ring surface at various scales was established based on the finite element method. A bottom-up modeling approach was adopted to construct a geometric model of the decomposed three-dimensional surface data. The contact of the rough surface was equivalent to the contact between a rough surface and an ideal rigid plane. The multi-scale characteristics of the sealing contact surface and its characterization parameters were used to analyze the contact characteristics of each scale and the influence between scales. The relationship and variation law between the contact stress and different roughness, materials, loads, and temperatures were analyzed. The contact behavior of surface components at different scales was revealed, and the influence of different scale components on the sealing performance was explored. Combined with the influence of the corresponding scale on the surface functional properties, a mapping between the sealing performance of the underwater wellhead connector and the surface morphology of the metal sealing ring was established, thereby achieving the purpose of reversely regulating the surface morphology of the metal sealing ring according to the sealing performance requirements.

[0073] like Figure 4 As shown in the figure, a rectangular region on the sealing contact interface of an underwater wellhead connector is selected as the research object. Based on the percolation theory, a grid leakage model for the sealing contact surface of the underwater wellhead connector is established. The contact area is discretized into a rectangular grid, with the actual contact area "occupied" by black grids. The process of the sealing interface contact is the process of grid "occupying" grids. A is defined as the actual contact area and A0 as the theoretical contact area. The actual contact area is a characteristic quantity that varies with the preload, so the dimensionless contact area ratio A / A0 is used as a control parameter for the grid properties. When A / A0 = 0.8, the contact interface is sealed. As the contact area ratio decreases, the actual contact area gradually decreases and the residual gap gradually increases. When the contact area ratio decreases to a certain value, a leakage channel appears, and the sealing interface enters a leaking state. A path-finding algorithm (known algorithm) is used to simulate the flow of fluid at the sealing interface. Based on the previously analyzed influence of contact area, contact load, material, roughness, etc., the influence of contact area on the evolution of the sealing-leakage state of the sealing interface is analyzed, and the nature of the leakage at the sealing interface of the underwater wellhead connector is explored.

[0074] In order to further accurately calculate the seal leakage rate, the theoretical expression of the leakage rate is obtained by solving the Navier-Stokes equation for forming a straight leakage channel:

[0075]

[0076] Where ρ is the density of the fluid, u is the velocity vector, p is the pressure, μ is the dynamic viscosity of the fluid, and x is the channel direction. and The equation is further simplified to

[0077] Solve this second-order ordinary differential equation by performing two integrals.

[0078]

[0079] L is the channel length. Due to the symmetry assumption at x = 0 and x = L, u(0) = u(L), and the integration constant can be determined and C2=0, the velocity distribution formula is:

[0080]

[0081] The leakage rate Q is equal to the integral of the velocity over the channel cross-sectional area A, so the theoretical expression of the leakage rate is

[0082] Where A is the channel cross-sectional area; is the dynamic viscosity of the fluid; is the pressure; is the leakage rate; and Δ is the pressure difference.

[0083] Based on the theoretical expression of leakage rate, the experimental research is carried out to verify the theoretical model and numerical results, and to provide experimental verification and basis for the application of the underwater wellhead connector.

[0084] The underwater wellhead connector sealing leakage analysis method can establish the mapping relationship between the sealing performance and the surface topography, explore the leakage nature of the sealing interface of the underwater wellhead connector, develop the leakage rate prediction method considering the surface roughness and the surface sealing gap height, and provide a theoretical basis for the design of the sealing surface of the underwater wellhead connector.

[0085] The second aspect of the present application provides an underwater wellhead connector sealing leakage analysis device, comprising:

[0086] The first processing unit is used for obtaining the surface topography of the metal sealing ring in the underwater wellhead connector.

[0087] The second processing unit is used for carrying out multi-scale decomposition and characterization on the surface topography of the metal sealing ring based on the wavelet transform method, and obtaining different scale surface components of the metal sealing ring.

[0088] The third processing unit is used for establishing a multi-scale contact model of the metal sealing of the underwater wellhead connector, analyzing the contact behavior of the different scale surface components of the metal sealing ring and the influence on the sealing performance.

[0089] The fourth processing unit is used for establishing a sealing contact surface grid leakage model of the underwater wellhead connector based on the percolation theory, and analyzing the sealing-leakage state of the sealing interface and the change rule thereof.

[0090] The fifth processing unit is used for solving the Navier-Stokes equation of the leakage channel based on the sealing contact surface grid leakage model of the underwater wellhead connector, and obtaining the theoretical expression of the leakage rate.

[0091] The sixth processing unit is used for carrying out the experimental research based on the theoretical expression of the leakage rate and the influence of the contact behavior of the different scale surface components of the metal sealing ring on the sealing performance, verifying the theoretical model and numerical results, and providing experimental verification and basis for the application of the underwater wellhead connector.

[0092] The third aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the underwater wellhead connector sealing leakage analysis method of any one of the above.

[0093] The fourth aspect of the present application provides a computer device, which comprises a memory, a processor and a computer program stored on the memory and executable on the processor, and the processor realizes the steps of the underwater wellhead connector sealing leakage analysis method of any one of the above when executing the computer program.

[0094] The present application is described in terms of flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments. It will be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowcharts and / or block diagrams block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks.

[0095] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks.

[0096] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks.

[0097] Finally, it should be noted that the above-mentioned embodiments are merely intended to illustrate the technical solutions of the present application, rather than limit the technical solutions of the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still make modifications to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for analyzing seal leakage of an underwater wellhead connector, characterized in that: include: Obtain the surface morphology of the metal sealing ring in the underwater wellhead connector; The surface morphology of the metal sealing ring is decomposed and characterized at multiple scales based on the wavelet transform method to obtain the surface components of the metal sealing ring at different scales. Establish a multi-scale contact model for the metal seal of an underwater wellhead connector, and analyze the contact behavior of different-scale surface components of the metal seal ring and its impact on the sealing performance; Based on the percolation theory, a grid leakage model of the sealing contact surface of the underwater wellhead connector is established to analyze the sealing-leakage state and its changing law of the sealing interface. Based on the grid leakage model of the sealing contact surface of the underwater wellhead connector, the Navier-Stokes equations that form the leakage channel are solved to obtain the theoretical expression of the leakage rate. Based on the theoretical expression of leakage rate and the contact behavior of different scale surface components of metal sealing rings and their impact on sealing performance, relevant experimental research is carried out to verify the theoretical model and numerical results, providing experimental verification and basis for the application of underwater wellhead connectors; Based on the percolation theory, a grid leakage model of the sealing contact surface of the underwater wellhead connector is established. The specific process is as follows: A rectangular area on the sealing contact interface of the underwater wellhead connector is extracted as the research object, namely the contact area. The contact area is discretized into a rectangular grid, and the actual contact area is "occupied" by the black grid. The process of sealing interface contact is the process of the grid being "occupied". A is defined as the actual contact area and A0 as the theoretical contact area. The actual contact area is a characteristic quantity that changes with the preload, so the dimensionless contact area ratio A / A0 is used as the control parameter of the grid property.

2. The underwater wellhead connector seal leakage analysis method according to claim 1, characterized in that: The multi-scale contact model of the metal seal of the underwater wellhead connector is established based on the following assumptions: The underwater wellhead connector is regarded as a smooth rigid plane, the metal sealing ring is regarded as a rough micro-convex body, and the sealing contact is assumed to be the contact between a rigid smooth plane and a sphere. A multi-scale contact model of the metal seal of the underwater wellhead connector is established.

3. The underwater wellhead connector seal leakage analysis method according to claim 2, characterized in that: Analyze the contact behavior of different scale surface components of metal sealing rings and their impact on sealing performance. The specific process is as follows: The contact behavior of metal sealing rings is analyzed based on Hertz contact theory, and the theoretical relationship between the deformation, contact area and contact load of metal sealing rings in the elastic and plastic regions is derived.

4. The underwater wellhead connector seal leakage analysis method according to claim 3, characterized in that: Based on the finite element method, a contact model of each scale of the sealing ring surface obtained by actual measurement is established. A bottom-up modeling method is used to construct a geometric model of the decomposed three-dimensional surface data. The contact of the rough surface is equivalent to the contact between a rough surface and an ideal rigid plane. The multi-scale characteristics of the sealing contact surface and its characterization parameters are used to analyze the contact characteristics of each scale and the influence between scales. The relationship and change law between contact stress and different roughness, materials, loads, and temperatures are analyzed, revealing the contact behavior of surface components of different scales, exploring the influence of components of different scales on the sealing performance, and combining the influence of the corresponding scale on the functional properties of the surface to establish a mapping between the sealing performance of the underwater wellhead connector and the surface morphology of the metal sealing ring, thereby achieving the purpose of reversely regulating the surface morphology of the metal sealing ring according to the sealing performance requirements.

5. The underwater wellhead connector seal leakage analysis method according to claim 1, characterized in that: To explore the sealing-leakage state and its changing rules of the sealing interface, the specific process is as follows: The path-finding algorithm is used to simulate the flow process of the fluid medium at the sealing interface. The mathematical expression of the state evolution curve is obtained by fitting the cumulative distribution function. Based on the previously analyzed contact area and the influence rules including contact load, material, and roughness, the influence of the contact area on the sealing-leakage state evolution characteristics of the sealing interface is analyzed, and the leakage law of the sealing interface of the underwater wellhead connector is explored.

6. The underwater wellhead connector seal leakage analysis method according to claim 5, characterized in that: In order to further accurately calculate the seal leakage rate, the theoretical expression of the leakage rate is obtained by solving the Navier-Stokes equation for forming a straight leakage channel: Where, A is the channel cross-sectional area; is the dynamic viscosity of the fluid; It’s pressure; is the leakage rate; It's the pressure difference.

7. An underwater wellhead connector seal leakage analysis device, characterized in that: include: The first processing unit is used to obtain the surface morphology of the metal sealing ring in the underwater wellhead connector; The second processing unit is used to perform multi-scale decomposition and characterization of the surface morphology of the metal sealing ring based on the wavelet transform method to obtain surface components of the metal sealing ring at different scales; The third processing unit is used to establish a multi-scale contact model of the metal seal of the underwater wellhead connector to analyze the contact behavior of the surface components of the metal seal ring at different scales and their impact on the sealing performance; The fourth processing unit is used to establish a grid leakage model of the sealing contact surface of the underwater wellhead connector based on the percolation theory, and analyze the sealing-leakage state and its changing law of the sealing interface; a fifth processing unit, configured to solve the Navier-Stokes equations for forming leakage channels based on a grid leakage model of a sealing contact surface of an underwater wellhead connector, and obtain a theoretical expression for a leakage rate; The sixth processing unit is used to conduct relevant experimental research to verify the theoretical model and numerical results based on the theoretical expression of leakage rate and the contact behavior of different scale surface components of the metal sealing ring and its impact on sealing performance, providing experimental verification and basis for the application of underwater wellhead connectors; Based on the percolation theory, a grid leakage model of the sealing contact surface of the underwater wellhead connector is established. The specific process is as follows: A rectangular area on the sealing contact interface of the underwater wellhead connector is extracted as the research object, namely the contact area. The contact area is discretized into a rectangular grid, and the actual contact area is "occupied" by the black grid. The process of sealing interface contact is the process of the grid being "occupied". A is defined as the actual contact area and A0 as the theoretical contact area. The actual contact area is a characteristic quantity that changes with the preload, so the dimensionless contact area ratio A / A0 is used as the control parameter of the grid property.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the underwater wellhead connector seal leakage analysis method according to any one of claims 1 to 6 are implemented.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the underwater wellhead connector seal leakage analysis method according to any one of claims 1 to 6 are implemented.

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