Underwater wellhead connector sealing leakage analysis method

Abstract

The invention relates to a sealing leakage analysis method for an underwater wellhead connector. The method comprises the steps that the surface appearance of a metal sealing ring in the underwater wellhead connector is obtained; performing multi-scale decomposition and characterization on the surface appearance of the metal sealing ring to obtain different-scale surface components of the metal sealing ring; establishing a metal sealing multi-scale contact model of the underwater wellhead connector, and analyzing contact behaviors of different-scale surface components of the metal sealing ring and influences on the sealing performance; establishing a grid leakage model of the sealing contact surface of the underwater wellhead connector, and analyzing a sealing-leakage state and a change rule of the sealing-leakage state of the sealing interface; based on the grid leakage model of the sealing contact surface of the underwater wellhead connector, solving a calculation equation for forming a leakage channel, and deducing a leakage rate prediction method when the surface roughness and the surface sealing gap height are considered; based on a leakage rate prediction method, related experimental research is carried out to verify a theoretical model and a numerical result, and experimental verification and basis are provided for application of the underwater wellhead connector.

Description

Technical Field

[0001] The present invention relates to a method for analyzing the seal leakage of an underwater wellhead connector, belonging to the technical field of offshore oil production. Background Art

[0002] The underwater wellhead connector is one of the key equipments for deep-sea oil and gas production, which has the functions of connecting the underwater wellhead and the Christmas tree, preventing the leakage of high-temperature and high-pressure oil and gas in the well, supporting the metal sealing ring, and bearing various complex loads. Its sealing problem is related to the safe production of offshore oil and gas. At present, there is a lack of a profound understanding of its most core sealing contact characteristics and leakage mechanism, which limits its engineering application.

[0003] The complex geometric shape and multi-scale nature of the rough surface of the metal sealing ring of the underwater wellhead connector bring great difficulties 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 theoretically, resulting in insufficient research on the sealing contact characteristics and leakage mechanism of the underwater wellhead connector. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a method for analyzing the seal leakage of an underwater wellhead connector, which can establish a mapping relationship between the sealing performance and the surface topography, explore the essence of the seal interface leakage of the underwater wellhead connector, develop a leakage rate prediction method considering the surface roughness and the height of the surface seal gap, and provide a theoretical basis for the design of the seal surface of the underwater wellhead connector.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for analyzing the seal leakage of an underwater wellhead connector, comprising:

[0007] Obtaining the surface topography of the metal sealing ring in the underwater wellhead connector;

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

[0009] Establishing a multi-scale contact model for the metal seal of the underwater wellhead connector, and analyzing the contact behavior of different-scale surface components of the metal sealing ring and their influence on the sealing performance;

[0010] Based on the percolation theory, establishing a grid leakage model for the seal contact surface of the underwater wellhead connector, and analyzing the seal-leakage state of the seal interface and its change law;

[0011] Based on the grid leakage model of the seal contact surface of the underwater wellhead connector, solving the Navier-Stokes equation for forming the leakage channel to obtain the theoretical expression of the leakage rate;

[0012] Based on the theoretical expression of the leakage rate, the contact behavior of different-scale surface components of the metal sealing ring, and its influence on the sealing performance, relevant experimental studies are carried out to verify the theoretical model and numerical results, providing experimental verification and basis for the application of underwater wellhead connectors.

[0013] The method for analyzing the seal leakage of the underwater wellhead connector, preferably, establishing a multi-scale contact model of the metal seal of the underwater wellhead connector, is based on the following assumptions:

[0014] Regarding the underwater wellhead as a smooth rigid plane and the metal sealing ring as rough micro-protrusions, assuming the seal contact as 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.

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

[0016] Based on Hertz contact theory, analyze the contact behavior of the metal sealing ring, and derive the theoretical relationships of the deformation amount, contact area, and contact load of the metal sealing ring in the elastic region and plastic region.

[0017] The method for analyzing the seal leakage of the underwater wellhead connector, preferably, in order to further analyze the contact behavior on each scale component of the surface of the measured metal sealing ring of the underwater wellhead connector, establish a contact model of each scale on the surface of the measured sealing ring based on the finite element method. Adopt the bottom-up modeling method to construct a geometric model from the decomposed three-dimensional surface data. Equivalent the contact of the rough surface to the contact between a rough surface and an ideal rigid plane. Use the multi-scale characteristics and their characterization parameters of the seal contact surface to analyze the contact characteristics of each scale and the influence between scales, analyze the relationship and variation law between contact stress and different roughness, materials, loads, and temperatures, reveal the contact behavior of different-scale surface components, explore the influence of different-scale components on the sealing performance, and combine the influence of the corresponding scale on the surface functional attributes to establish the mapping between the sealing performance of the underwater wellhead connector and the surface topography of the metal sealing ring, so as to achieve the purpose of reversely regulating the surface topography of the metal sealing ring according to the sealing performance requirements.

[0018] The method for analyzing the seal leakage of the underwater wellhead connector, preferably, based on the percolation theory, establish a grid leakage model of the seal contact surface of the underwater wellhead connector, the specific process is as follows:

[0019] Extract a rectangular area on the sealing contact interface of the subsea wellhead connector as the research object, that is, the contact area. Discretize the contact area into rectangular grids. The actual contact area is "occupied" by black grids. The process of the sealing interface contact is the process of the grids being "occupied". Define A as the actual contact area and A0 as the theoretical contact area. The actual contact area is a characteristic quantity that changes with the pre-tightening load. Therefore, the dimensionless contact area ratio A / A0 is used as the control parameter for the grid attributes.

[0020] The above-mentioned subsea wellhead connector seal leakage analysis method. Preferably, explore the sealing-leakage state of the sealing interface and its change law. The specific process is as follows:

[0021] Use the path-finding algorithm to simulate the flow process of the fluid medium on the sealing interface, obtain the mathematical expression of the state evolution curve by fitting the cumulative distribution function, and analyze the influence of the contact area on the sealing-leakage state evolution characteristics of the sealing interface based on the influence laws of the contact area including contact load, material, and roughness, so as to explore the leakage law of the subsea wellhead connector sealing interface.

[0022] The above-mentioned subsea wellhead connector seal leakage analysis method. Preferably, in order to calculate the seal leakage rate more accurately, solve the Navier-Stokes equation for forming a straight leakage channel to obtain the theoretical expression of the leakage rate; based on the theoretical expression of the leakage rate, carry out relevant experimental studies to verify the theoretical model and numerical results, and provide experimental verification and basis for the application of the subsea wellhead connector.

[0023] The second aspect of the present invention provides a subsea wellhead connector seal leakage analysis device, including:

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

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

[0026] The third processing unit is used to establish a multi-scale contact model for the metal seal of the subsea wellhead connector, and analyze the contact behavior of different scale surface components of the metal sealing ring and its influence on the sealing performance;

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

[0028] The fifth processing unit is used to solve the Navier-Stokes equation for forming a leakage channel based on the grid leakage model of the sealing contact surface of the subsea wellhead connector to obtain the theoretical expression of the leakage rate;

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

[0030] The third aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the underwater wellhead connector sealing leakage analysis method described in any one of the above are realized.

[0031] The fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and operable on the processor. When the processor executes the computer program, the steps of the underwater wellhead connector sealing leakage analysis method described in any one of the above are realized.

[0032] Due to the adoption of the above technical solutions, the present invention has the following advantages:

[0033] Starting from the surface topography of the metal sealing ring of the underwater wellhead connector, first, based on the wavelet transform method, the surface topography of the contact surface of the metal sealing ring is decomposed and characterized at multiple scales, a multi-scale contact model of the metal seal 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 to reveal the sealing-leakage state and its change law of the sealing interface; secondly, the Navier-Stokes equation for forming the leakage channel is solved, and a leakage rate prediction method considering surface roughness and surface sealing gap height is derived; finally, relevant experimental studies are carried out to verify the theoretical model and numerical results. The implementation of this article will enrich and improve the sealing theory of the underwater wellhead connector and provide scientific support for the application of the underwater wellhead connector. Description of the Drawings

[0034] Figure 1 It is a schematic connection diagram of the underwater wellhead connector, the wellhead, and the production tree body provided by an embodiment of the present invention;

[0035] Figure 2 It is a flowchart of the underwater wellhead connector sealing leakage analysis method provided by this embodiment of the present invention;

[0036] Figure 3 It is a microscopic contact model diagram of the underwater wellhead connector provided by this embodiment of the present invention;

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

[0038] Figure 5 This is the leakage channel model diagram of the underwater wellhead connector provided by this embodiment of the present invention;

[0039] Figure 6 is Figure 5 side view of;

[0040] The reference numerals are as follows:

[0041] 1 - indicating mechanism; 2 - production tree body; 3 - metal sealing ring; 4 - locking block; 5 - wellhead connector body; 6 - driving piston; 7 - secondary unlocking piston; 8 - acting ring; 9 - wellhead. Detailed implementation manners

[0042] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention pertains. The "first", "second", "third", "fourth" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or items appearing before this word cover the elements or items listed after this word and their equivalents, without excluding other elements or items. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0044] For the convenience of description, spatial relative relationship terms can be used in the text to describe the relationship of one element or feature shown in the figure relative to another element or feature. These relative relationship terms such as "inner", "outer", "inner side", "outer side", "below", "above", etc. are intended to include different orientations of the device in use or operation other than the orientations depicted in the figure.

[0045] One of the prior arts discloses a method for analyzing the structural seal of rubber. This method mainly involves secondary development of computer simulation software, including creating a finite element model of the rubber structure; defining the material properties of the rubber structure; defining the contact of the rubber structure; defining the result output; defining the boundaries and working conditions; submitting the solver for calculation; and automatically post-processing the results. By secondary development of general CAE software, the process of structural seal analysis is made flow-based and automated. This solution has the following drawbacks: There are significant differences in the surface roughness of rubber parts. Therefore, when calculating the seal condition of the rubber structure using an ideal model, the influence of the surface roughness amplitude of the contact interface on the leakage of the seal is ignored. The influence of the surface roughness amplitude of the contact interface on the leakage of the seal is not taken into account in this calculation process.

[0046] Another prior art discloses a method for modeling a stochastic model of the degradation of the sealing performance of an underwater connector. It uses the sealing contact strength as a performance index, constructs a thermal-solid finite element analysis model of the connector's sealing performance, and analyzes the sealing performance at the initial moment. 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 moments. By repeating this process, they obtain the sealing performance indexes at different time points. Finally, they use the Gamma stochastic process to describe the degradation of the sealing performance and estimate the characteristic parameters of this process, thus establishing a degradation model of the connector's sealing performance based on the Gamma process. This solution has the following drawbacks: The degradation of the sealing performance may have serious consequences. This invention proposes a method for modeling a stochastic model of the degradation of the sealing performance of an underwater connector, which is a model for analyzing the degradation of the sealing performance from a macroscopic perspective. However, if examined from a microscopic level, the morphological characteristics of the seal, including surface roughness, geometric shape, 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 seal.

[0047] The third prior art discloses an innovative method and system for the reliability analysis of underwater connectors, and its core features are summarized as follows: First, by accurately capturing the actual three-dimensional shape of the underwater connector to be tested, a corresponding finite element simulation model is constructed; Subsequently, the input parameters and potential failure modes of the model are analyzed in depth, and referring to the common failure cases of structurally similar mechanical equipment, the key vulnerable areas in the underwater connector to be tested are accurately identified; Furthermore, based on the identification results, a detailed finite element analysis input strategy is formulated to simulate and calculate the stress and strain distribution of the connector; Then, for each vulnerable area, a dedicated reliability assessment model is constructed, and through the sampling analysis of the input scheme, the reliability index and failure probability of these areas are scientifically calculated. This solution has the following disadvantages: The results of this simulation analysis largely depend on the accuracy of the finite element model. 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 and may require high-performance computer hardware support. Implementing this method requires an in-depth understanding of finite element analysis and Monte Carlo analysis, has high requirements for the professional knowledge of operators, and the interpretation of simulation results may require professional knowledge and may be difficult for non-professionals to understand.

[0048] The complex geometric shape and multi-scale nature of the rough surface of the metal sealing ring of the underwater wellhead connector bring great difficulties 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 theoretically, resulting in insufficient research on the sealing contact characteristics and leakage mechanism of the underwater wellhead connector.

[0049] Based on the above technical problems, the present invention provides a method for analyzing the sealing leakage of an underwater wellhead connector. It aims to solve two key problems that have not been clarified for deep-sea underwater wellhead connectors: one is what kind of sealing contact characteristics the underwater wellhead connector has under service conditions; the other is how to judge the sealing-leakage state and its evolution law of the contact interface of the underwater wellhead connector.

[0050] As Figure 1As shown in the figure, the method for analyzing the seal leakage of the underwater wellhead connector provided by the present invention is based on the metal seal structure of the underwater wellhead connector. The structure includes: an action ring 8 sleeved on the wellhead 9. The action ring 8 includes a first action ring and a second action ring integrally formed coaxially. The outer diameter of the second action ring is smaller than that of the first action ring; a wellhead connector body 5. A trumpet-shaped accommodation cavity penetrating its axis is provided in the wellhead connector body 5. The small-diameter end of the accommodation cavity is connected to the production tree body 2 through a flange. The large-diameter end of the accommodation cavity is used to accommodate the action ring 8. The first action ring is connected to the inner wall of the wellhead connector body 5, and a gap is left between the second action 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 action ring, located in the gap and connected to the inner wall of the wellhead connector body 5. The driving piston 6 is located above the secondary unlocking piston 7; a lock block 4 is sleeved on the wellhead 9 and connected to the lower end surface of the production tree body 2. Teeth meshing with the tooth grooves of the wellhead 9 are provided on the lock block 4. The outer wall surface of the lock block 4 contacts the upper end inner wall surface of the driving piston 6; a metal sealing ring 3 is assembled on the top of the wellhead 9 and located in the cavity of the production tree body 2 for sealing the wellhead 9 and the production tree body 2.

[0051] As Figure 2 shown, the method for analyzing the seal leakage of the underwater wellhead connector of the present invention includes the following specific steps:

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

[0053] S2: Based on the wavelet transform method, perform multi-scale decomposition and characterization on the surface topography of the metal sealing ring to obtain different-scale surface components of the metal sealing ring;

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

[0055] S4: Based on the percolation theory, establish a grid leakage model for the seal contact surface of the underwater wellhead connector, and analyze the seal-leakage state of the seal interface and its change law;

[0056] S5: Based on the grid leakage model of the seal contact surface of the underwater wellhead connector, solve the Navier-Stokes equation for forming the leakage channel to obtain the theoretical expression of the leakage rate;

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

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

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

[0060] where the scale j = 1 to 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 metal sealing ring of the underwater wellhead connector; A N (x1,x2) is the approximate signal at the Nth level; D N (x1,x2)……D1(x1,x2) are the detail signals at 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 consists of the high-frequency coefficient D j (h) in the horizontal direction, the high-frequency coefficient D j (v) in the vertical direction, and the high-frequency coefficient D j (d) in the diagonal direction:

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

[0065] By analyzing the amplitude-frequency characteristics and phase-frequency characteristics, comparing the performance of various wavelet filters, and selecting a suitable wavelet to achieve the multi-scale decomposition and reconstruction of the three-dimensional surface. The surface is decomposed by a multi-scale filter, and the surface signal is decomposed into N levels (N > 1). The logical relationship of the decomposed signals is shown in formula (4), where A N represents the approximate signal at the Nth level, DN respectively represent the detail signals of the Nth level.

[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 engineering practical problems, the relationship between the wavelet scale and the surface physical scale is established as follows:

[0068]

[0069] In the formula, △L is the sampling interval of the measured surface, F c is the central frequency of the wavelet, F s and D s represent 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 is sampled, so that the surface features of this scale can be fully included in the deterministic model. In ANSYS, using the APDL parametric modeling language and the bottom-up modeling method, the three-dimensional surface data obtained by decomposition is used to construct a geometric model, and a geometric contact model of rough surfaces at different scales is established.

[0071] As Figure 3 shown, regarding the underwater wellhead as a smooth rigid plane and the metal sealing ring as rough micro-protrusions, assuming the seal contact as 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. Based on Hertz contact theory, the contact behavior of the metal sealing ring is analyzed, and the theoretical relationships (known) of the deformation amount, contact area, and contact load of the metal sealing ring in the elastic region and plastic region are deduced.

[0072] In order to further analyze the contact behavior on each scale component of the surface of the measured metal sealing ring of the underwater wellhead connector, a contact model of each scale of the measured sealing ring surface is established based on the finite element method. Using the bottom-up modeling method, the three-dimensional surface data obtained by decomposition is used to construct a geometric model. 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 their characterization parameters of the seal contact surface are used to analyze the contact characteristics of each scale and the influence between scales, analyze the relationship and variation law between contact stress and different roughness, materials, loads, and temperatures, reveal the contact behavior of different scale surface components, explore the influence of different scale components on the sealing performance, and combine the influence of the corresponding scale on the surface functional attributes to establish a mapping between the sealing performance of the underwater wellhead connector and the surface topography of the metal sealing ring, so as to achieve the purpose of reversely regulating the surface topography of the metal sealing ring according to the sealing performance requirements.

[0073] As shown Figure 4 in the figure, a rectangular area on the sealing contact interface of the underwater wellhead connector is extracted as the research object. Based on the percolation theory, a grid leakage model of the sealing contact surface of the underwater wellhead connector is established. The contact area is discretized into rectangular grids, and the actual contact area is "occupied" by black grids. The process of the sealing interface contact is the process of the grids being "occupied". Define A as the actual contact area and A0 as the theoretical contact area. The actual contact area is a characteristic quantity that changes with the pre-tightening load. Therefore, the dimensionless contact area ratio A / A0 is used as the control parameter of the grid attribute. When A / A0 = 0.8, the contact interface is in a sealed state. As the contact area ratio decreases, the actual contact area gradually decreases and the residual voids gradually increase. When the contact area ratio decreases to a certain value, a leakage channel appears and the sealing interface is in a leakage state. The path-finding algorithm (known algorithm) is used to simulate the flow process of the fluid medium on the sealing interface. Based on the influence laws of the contact area on the contact load, material, roughness, etc. analyzed above, the influence of the contact area on the sealing-leakage state evolution characteristics of the sealing interface is analyzed to explore the essence of the leakage of the underwater wellhead connector sealing interface.

[0074] To further accurately calculate the sealing leakage rate, by solving the Navier-Stokes equation for the formation of a straight leakage channel, the theoretical expression for the leakage rate is obtained:

[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. Since it is a steady flow and the equation is further simplified to

[0077] This second-order ordinary differential equation is solved by integrating twice.

[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 constants and C2 = 0 can be determined. The velocity distribution formula is:

[0080]

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

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

[0083] Based on the theoretical expression of the leakage rate, relevant experimental studies are carried out to verify the theoretical model and numerical results, providing experimental verification and basis for the application of underwater wellhead connectors.

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

[0085] The second aspect of the present invention provides an apparatus for analyzing the seal leakage of an underwater wellhead connector, including:

[0086] A first processing unit for obtaining the surface topography of the metal sealing ring in the underwater wellhead connector;

[0087] A second processing unit for performing multi-scale decomposition and characterization on the surface topography of the metal sealing ring based on the wavelet transform method to obtain different-scale surface components of the metal sealing ring;

[0088] A third processing unit for establishing a multi-scale contact model of the metal seal of the underwater wellhead connector and analyzing the contact behavior of different-scale surface components of the metal sealing ring and its influence on the sealing performance;

[0089] A fourth processing unit for establishing a grid leakage model of the sealing contact surface of the underwater wellhead connector based on the percolation theory and analyzing the sealing-leakage state of the sealing interface and its changing rules;

[0090] A fifth processing unit for solving the Navier-Stokes equation for forming a leakage channel based on the grid leakage model of the sealing contact surface of the underwater wellhead connector to obtain the theoretical expression of the leakage rate;

[0091] A sixth processing unit for carrying out relevant experimental studies based on the theoretical expression of the leakage rate and the contact behavior of different-scale surface components of the metal sealing ring and its influence on the sealing performance to verify the theoretical model and numerical results, providing experimental verification and basis for the application of the underwater wellhead connector.

[0092] The third aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method for analyzing the seal leakage of the underwater wellhead connector described in any one of the above are implemented.

[0093] The fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the computer program, the steps of the method for analyzing the seal leakage of the underwater wellhead connector described in any one of the above are implemented.

[0094] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to specific embodiments. It should be understood that each flow and / or block in the flowchart and / or block diagram, and combinations of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices produce means for implementing the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 block or multiple 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 device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 block or multiple blocks.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 block or multiple blocks.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for 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 various embodiments of the present invention.

Claims

1. A method for analyzing the seal leakage of an underwater wellhead connector, characterized in that, Including: Obtain the surface topography of the metal sealing ring in the subsea wellhead connector; Based on the wavelet transform method, perform multi-scale decomposition and characterization on the surface topography of the metal sealing ring to obtain different-scale surface components of the metal sealing ring; Establish a multi-scale contact model for metal sealing in the subsea wellhead connector, and analyze the contact behavior of different-scale surface components of the metal sealing ring and its influence on the sealing performance; Based on the percolation theory, establish a grid leakage model for the sealing contact surface of the subsea wellhead connector, and analyze the sealing-leakage state and its variation law of the sealing interface; Based on the grid leakage model of the sealing contact surface of the subsea wellhead connector, solve the Navier-Stokes equation for forming the leakage channel to obtain the theoretical expression of the leakage rate; Based on the theoretical expression of the leakage rate, the contact behavior of different-scale surface components of the metal sealing ring and its influence on the sealing performance, carry out relevant experimental studies to verify the theoretical model and numerical results, and provide experimental verification and basis for the application of the subsea wellhead connector.

2. The method for analyzing the seal leakage of the underwater wellhead connector according to claim 1, wherein The establishment of the multi-scale contact model for metal sealing in the subsea wellhead connector is based on the following assumptions: Regard the subsea wellhead as a smooth rigid plane, and the metal sealing ring as rough micro-protrusions. Assume the sealing contact as the contact between a rigid smooth plane and a sphere, and establish a multi-scale contact model for metal sealing in the subsea wellhead connector.

3. The method for analyzing the seal leakage of the underwater wellhead connector according to claim 2, wherein, Analyze the contact behavior of different-scale surface components of the metal sealing ring and its influence on the sealing performance. The specific process is as follows: Based on the Hertz contact theory, analyze the contact behavior of the metal sealing ring, and derive the theoretical relationships of the deformation amount, contact area, and contact load of the metal sealing ring in the elastic region and the plastic region.

4. The method for analyzing the seal leakage of the underwater wellhead connector according to claim 3, characterized in that, Based on the finite element method, establish contact models for each scale of the measured sealing ring surface. Adopt the bottom-up modeling method to construct a geometric model from the decomposed three-dimensional surface data. Equivalent the contact of the rough surface to the contact between a rough surface and an ideal rigid plane. Use the multi-scale characteristics and their characterization parameters of the sealing contact surface to analyze the contact characteristics of each scale and the influence between scales. Analyze the relationships and variation laws between contact stress and different roughness, materials, loads, and temperatures, reveal the contact behavior of different-scale surface components, explore the influence of different-scale components on the sealing performance, and combine the influence of the corresponding scale on the surface functional attributes to establish a mapping between the sealing performance of the subsea wellhead connector and the surface topography of the metal sealing ring, so as to achieve the purpose of reversely regulating the surface topography of the metal sealing ring according to the sealing performance requirements.

5. The method for analyzing the seal leakage of the underwater wellhead connector according to claim 4, characterized in that, Based on the percolation theory, establish a grid leakage model for the sealing contact surface of the subsea wellhead connector. The specific process is as follows: Extract a rectangular area on the sealing contact interface of the subsea wellhead connector as the research object, that is, the contact area. Discretize the contact area into rectangular grids. The actual contact area is "occupied" by black grids. The process of sealing interface contact is the process of grids being "occupied". Define A as the actual contact area and A0 as the theoretical contact area. The actual contact area is a characteristic quantity that changes with the pre-tightening load. Therefore, take the dimensionless contact area ratio A / A0 as the control parameter of the grid attribute.

6. The method for analyzing the seal leakage of the underwater wellhead connector according to claim 5, wherein Explore the sealing-leakage state of the sealing interface and its variation law. The specific process is as follows: Use the path-finding algorithm to simulate the flow process of the fluid medium at the sealing interface, obtain the mathematical expression of the state evolution curve by fitting the cumulative distribution function, and analyze the influence of the contact area on the sealing-leakage state evolution characteristics of the sealing interface based on the influence laws of the contact area including contact load, material, and roughness, so as to explore the leakage law of the sealing interface of the underwater wellhead connector.

7. The underwater wellhead connector seal leakage analysis method according to claim 6, wherein, In order to calculate the sealing leakage rate more accurately, by solving the Navier-Stokes equation for forming a straight leakage channel, the theoretical expression of the leakage rate is obtained: In the formula, A is the cross-sectional area of the channel; μ is the dynamic viscosity of the fluid; p is the pressure; Q is the leakage rate; Δ is the pressure difference.

8. An underwater wellhead connector seal leakage analysis device, characterized in that, Including: The first processing unit is used to obtain the surface topography of the metal sealing ring in the underwater wellhead connector; The second processing unit is used to perform multi-scale decomposition and characterization on the surface topography of the metal sealing ring based on the wavelet transform method to obtain different-scale surface components of the metal sealing ring; The third processing unit is used to establish a multi-scale contact model of the metal seal of the underwater wellhead connector, and analyze the contact behavior of different-scale surface components of the metal sealing ring and its influence 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 of the sealing interface and its variation law; The fifth processing unit is used to solve the Navier-Stokes equation for forming a leakage channel based on the grid leakage model of the sealing contact surface of the underwater wellhead connector to obtain the theoretical expression of the leakage rate; The sixth processing unit is used to carry out relevant experimental studies to verify the theoretical model and numerical results based on the theoretical expression of the leakage rate and the contact behavior of different-scale surface components of the metal sealing ring and its influence on the sealing performance, so as to provide experimental verification and basis for the application of the underwater wellhead connector.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the underwater wellhead connector sealing leakage analysis method described in any one of claims 1-7 are implemented.

10. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps of the underwater wellhead connector sealing leakage analysis method described in any one of claims 1-7 are implemented.

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