Deepwater Christmas tree lowering simulation system and method

Abstract

The invention provides a deepwater Christmas tree lowering simulation system and method, and belongs to the technical field of Christmas trees, the deepwater Christmas tree lowering simulation system comprises a test water tank, a wave making device, a flow making device, a measuring device, a data processing device and a Christmas tree lowering model capable of being lowered into the test water tank; the test water tank is used for storing test water and providing a place required by the test; the wave making device is used for forming waves in the test water tank; the flow generation device is used for forming water flow in the test water tank; the measuring device is used for measuring the deformation state of the Christmas tree lowering model; and the data processing device is used for processing and analyzing the measured data and determining the influence degree of waves and water flow on the Christmas tree lowering model. According to the invention, a stable and controllable test environment is provided to simulate the influence degree of the marine environment on the Christmas tree during lowering, and the effects of different marine environment parameters on the Christmas tree are evaluated, so that the design of the Christmas tree and the lowering stability of the Christmas tree are guided.

Description

Technical Field

[0001] The invention relates to the technical field of Christmas trees, and in particular to a deepwater Christmas tree lowering simulation system and method. Background Art

[0002] The Christmas tree is one of the key production equipment in offshore oil and gas fields. It undertakes multiple tasks such as controlling the oil and gas flow and isolating the wellhead from the external environment. That is, the Christmas tree is not only responsible for controlling the oil and gas flow from the bottom of the well to the sea surface, but also plays a role in isolating the wellhead from the surrounding environment, ensuring the safe and effective exploitation of oil and natural gas. Therefore, whether the Christmas tree can be properly installed is related to the stable production of the oil field. For deepwater oil and gas fields, the installation process of the Christmas tree is relatively complicated and is easily affected by various harsh environmental factors such as ocean currents and waves. During the lowering process, the rotation of the Christmas tree and the accuracy of the deepwater Christmas tree need to be remotely controlled. If the drill string strength is not enough or the lateral displacement of the drill string is too large during the lowering process, it will affect the safety of the Christmas tree lowering and the alignment installation with the wellhead. Therefore, it is necessary to analyze the interference of the marine environment during the lowering of the Christmas tree. However, at present, most of the numerical simulations of the lowering of the Christmas tree are performed by computer, lacking experimental verification, and the marine environment changes greatly. It is difficult and costly to directly place the Christmas tree in deep water for real experiments. Summary of the invention

[0003] In view of the above problems, the present invention provides a deepwater Christmas tree lowering simulation system and method, which provides a stable and controllable test environment to simulate the degree of influence of the marine environment during the lowering of the Christmas tree, evaluates the effect of different marine environmental parameters on the Christmas tree, guides the design of the Christmas tree, and ensures the safety and stability of the Christmas tree after it is lowered.

[0004] The present invention provides a deepwater Christmas tree lowering simulation system, comprising a test water tank, a wave making device, a flow making device, a measuring device, a data processing device and a Christmas tree lowering model that can be lowered into the test water tank; The test water tank is used to store test water and provide a place required for the test, wherein the test water tank simulates the marine environment and the water in the test water tank simulates seawater; The wave-making device is used to form waves in the test water tank to disturb the Christmas tree lowering model lowered in the test water tank; The flow-generating device is used to form a water flow with a set flow rate in the test water tank to disturb the Christmas tree lowering model lowered in the test water tank; The measuring device is used to measure the deformation state of the Christmas tree lowering model lowered into the test water tank under the influence of waves and water flow, and obtain the state data of the Christmas tree lowering model; The data processing device is used to process and analyze the status data of the Christmas tree lowering model obtained by the measuring device, and determine the influence degree of waves and water flow on the Christmas tree lowering model.

[0005] As a further improvement of the present invention, the wave-making device includes a wave maker and a wave breaker, wherein the wave maker is used to form waves in the test water tank, and the wave breaker is used to eliminate waves generated by reflection from the wall of the test water tank.

[0006] As a further improvement of the present invention, the Christmas tree lowering model is a drill string.

[0007] As a further improvement of the present invention, the drill string model is in a hollow cylindrical shape.

[0008] As a further improvement of the present invention, the test water tank is an open water tank.

[0009] As a further improvement of the present invention, the measuring device includes a digital photographic measurement module for recording the deformation process of the Christmas tree lowering model in the test water tank caused by the action of waves and currents.

[0010] The present invention provides a deepwater Christmas tree lowering simulation method, comprising: Acquiring Christmas tree lowering model data, and preparing a Christmas tree lowering model according to the Christmas tree lowering model data; Lowering the Christmas tree lowering model into a test water tank, and performing wave and flow generation in the test water tank to perform a simulation test on the Christmas tree lowering model; The state data of the Christmas tree lowering model during the simulation test is measured, and the influence of the water body on the Christmas tree lowering model is analyzed according to the state data.

[0011] As a further improvement of the present invention, the obtaining of the Christmas tree lowering model data and preparing the Christmas tree lowering model according to the Christmas tree lowering model data includes obtaining the Christmas tree lowering model data based on a deformation model and according to a gravity similarity principle.

[0012] As a further improvement of the present invention, lowering the Christmas tree lowering model to a test water tank, generating waves and currents in the test water tank to perform a simulation test on the Christmas tree lowering model includes utilizing the wave generating device and the current generating device to form different combinations of wave heights, periods and water flow velocities, and performing simulation tests under different combinations of wave heights, periods and water flow velocities.

[0013] As a further improvement of the present invention, the wave height range is 0.08m-0.12m, the period is 0.5s-1.0s, and the water flow velocity is 0.25m / s-0.35m / s.

[0014] As a further improvement of the present invention, measuring the status data of the Christmas tree lowering model during the simulation test and analyzing the influence of water on the Christmas tree lowering model based on the status data includes measuring lateral displacement data and lateral bending moment data of the Christmas tree lowering model, wherein the lateral displacement data and lateral bending moment data are measured using a displacement and bending moment measurement module fixed on the Christmas tree lowering model.

[0015] As a further improvement of the present invention, a plurality of displacement and bending moment measurement modules are arranged at intervals along the water depth direction on the Christmas tree lowering model.

[0016] As a further improvement of the present invention, the displacement and bending moment measurement module includes a resistance strain type displacement sensor and a resistance strain type torque sensor.

[0017] The present invention provides a deepwater Christmas tree lowering simulation system and method, provides a stable and controllable test environment to simulate the degree of influence of the marine environment during the lowering of the Christmas tree, evaluates the effect of different marine environmental parameters on the Christmas tree, guides the design of the Christmas tree, and ensures the safety and stability of the Christmas tree after it is lowered.

[0018] In the present invention, the seawater environment simulated by the test water tank, the waves formed by the wave-making device, and the water flow generated by the flow-making device together create a test environment that is as close to the actual ocean conditions as possible, which helps to more accurately evaluate the performance of the deep-water oil tree lowering operation; not only can the influence of waves or water flow on the oil tree lowering model be simulated separately, but the deformation of the oil tree lowering model under the combined effect of the two can also be considered at the same time, providing more comprehensive data to improve the oil tree design; compared with testing directly in the ocean, the system and method of the present invention can complete the test work in a simulated environment, reducing the difficulty and cost of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a deepwater Christmas tree lowering simulation system according to an embodiment of the present invention.

[0020] Figure 2 It is a structural schematic diagram of a Christmas tree lowering model of a deepwater Christmas tree lowering simulation system according to an embodiment of the present invention.

[0021] Figure 3 It is a flow chart of a deepwater Christmas tree lowering simulation method according to an embodiment of the present invention.

[0022] Figure 4 It is a schematic diagram of numerical segmentation of a drill string in a deepwater Christmas tree lowering simulation method according to an embodiment of the present invention.

[0023] Figure 5Schematic diagram of comparison of lateral displacement of drill string in a deepwater Christmas tree lowering simulation method according to an embodiment of the present invention.

[0024] Figure 6 Schematic diagram of comparison of the lateral bending moment of the drill string in the deepwater Christmas tree lowering simulation method according to an embodiment of the present invention.

[0025] Explanation of the reference numerals: 1. test water tank; 2. wave-making device; 3. flow-making device; 4. measuring device; 5. data processing device; 6. Christmas tree lowering model. DETAILED DESCRIPTION

[0026] The following is combined with specific embodiments and appendix Figure 1-6 The invention is described in detail so that those skilled in the art can more fully understand the purpose, features and effects of the invention.

[0027] Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. When the definition of a term in the present invention conflicts with the meaning commonly understood by those skilled in the art to which the present invention belongs, the definition described in the present invention shall prevail.

[0028] Subsea Christmas Tree is one of the key equipment used for offshore oil and gas extraction. The Subsea Christmas Tree is installed at the wellhead, located above the seabed, to control the flow of fluid in the well, including opening and closing the well and regulating production. The Subsea Christmas Tree is usually composed of valves, pressure gauges and other control devices, and can withstand extreme environmental conditions such as high pressure, low temperature and corrosion.

[0029] The present invention provides a deepwater Christmas tree lowering simulation system and method, which simulates the lowering of a deepwater Christmas tree in a stable and controllable environment and evaluates the impact of the marine environment on the Christmas tree.

[0030] Embodiment 1 As a specific embodiment of the present invention, this embodiment provides a deepwater Christmas tree lowering simulation system, which simulates the lowering of a deepwater Christmas tree. Figure 1 , Figure 2 , including a test water tank 1, a wave-making device 2, a flow-making device 3, a measuring device 4, a data processing device 5 and a Christmas tree lowering model 6 that can be lowered into the test water tank 1. The test water tank 1 is used to store test water and provide a place for lowering the Christmas tree lowering model 6. In this embodiment, the test water tank 1 simulates the ocean for lowering a deep-water Christmas tree. When performing the Christmas tree lowering simulation, the Christmas tree lowering model 6 is lowered into the water in the test water tank 1, wherein the water in the test water tank 1 simulates the seawater in the deep-water environment of the ocean. The water in the test water tank 1 disturbs the Christmas tree lowering model 6 when it moves, thereby simulating the interference of seawater on the Christmas tree in the deep-water environment. When no wave and current generation are performed, the water in the test water tank 1 is relatively static. The test water tank 1 in this embodiment is open, so that it is closer to the real ocean.

[0031] Preferably, the test water tank 1 is in the shape of a cuboid, and the size of the test water tank 1 is based on the simulation requirements. For example, the size of the test water tank 1 may be 62×2.0×2.0m. In other feasible embodiments, the test water tank 1 may also be in other shapes and sizes. Since the area where the Christmas tree is placed in the real marine environment is often far away from the coast, the impact of the wave current on the coast is small and can be almost ignored. Therefore, the size design of the test water tank 1 should take into account the possible impact of the tank wall of the test water tank 1 on the wave current as much as possible. The wave-making device 2 is used to disturb the water body in the test water tank 1, generate regular waves and irregular waves, form waves, and simulate various characteristics of natural waves, including wave height, wavelength, period and other indicators. The wave-making device 2 can generate waves of different wave heights and periods. Specifically, the wave-making device 2 includes a wave maker and a wave breaker, wherein the wave maker is used to disturb the water body in the test water tank 1 to generate waves, and the wave breaker is used to eliminate secondary waves in the test water tank 1 that are not generated by the wave maker, especially to eliminate waves generated by the reflection of the water flowing through the wall of the test water tank 1. Preferably, the wave maker is a hydraulic wave maker, which can generate waves with greater energy and high stability.

[0032] In this embodiment, by adjusting the parameter settings of the wave maker, different types of waves, such as sine waves, random waves, etc., can be generated, and the waves obtained can have different wave heights and periods to meet different test requirements. Compared with natural waves, the use of the wave maker can ensure that the wave environment provided is controllable, which helps to repeat the experiment under the same conditions and ensure the reliability and consistency of the data. The wave absorber can eliminate unnecessary wave reflections, which helps to maintain the purity of the wave morphology during the test, ensure that the environment in the water tank is as close as possible to the ideal open sea conditions, provide more realistic simulation conditions for the test, avoid errors caused by reflected waves, and improve the accuracy of the test.

[0033] The flow-generating device 3 is used to generate water flow in the test water tank 1 to simulate the characteristics of the sea current in the natural sea area. The flow-generating device 3 can generate a stable and evenly distributed water flow in the test water tank 1 to simulate the sea current conditions in the natural sea area. By changing and adjusting the parameter settings of the flow-generating device 3, the speed and direction of the water flow in the test water tank 1 can be adjusted to meet various requirements of the deep-water Christmas tree lowering test.

[0034] Specifically, the flow-generating device 3 includes a speed regulating pump, a water flow reversing valve, a circulation pipeline, a flow meter, a level water tank, a vortex elimination grid, and a guide plate. The flow-generating device 3 can make the water flow controllable, the flow velocity adjustable, and the flow direction reversible. The flow-generating device 3 can generate water flows with different flow velocities in the test water tank 1.

[0035] Furthermore, by cooperating with the wave-making device 2 and the flow-making device 3, wave flow is formed in the test water tank 1, which can simultaneously simulate the environment of the natural seawater flow and the waves in the sea area, achieve a better simulation effect, and thus improve the authenticity of the Christmas tree lowering simulation.

[0036] The measuring device 4 is used to measure the state of the lowering process of the Christmas tree lowering model 6 in the test water tank 1 and the state of the water body in the test water tank 1 and obtain state data. Specifically, the measuring device 4 includes a three-dimensional flow meter, a wave height meter, a water level meter, an anemometer, and a tracked measuring vehicle. For example, the three-dimensional flow meter is used to measure the water flow velocity in the test water tank 1, the wave height meter is used to measure the wave height of the waves in the test water tank 1, and the water level meter is used to measure the water level of the water body in the test water tank 1. The state data measured by the measuring device 4 is automatically acquired and stored, and then the state data is transmitted to the data processing device 5, which can be used for further analysis and processing.

[0037] Furthermore, parameter data of the wave-making device 2 and the flow-making device 3 are also transmitted to the data processing device 5 for further analysis and processing.

[0038] Further, the measuring device 4 includes a digital photogrammetry module. The digital photogrammetry module includes a digital camera, an incandescent lamp, punctuation marks and an image analysis unit. The digital photogrammetry module uses a high-resolution digital camera to photograph the Christmas tree lowering model 6 underwater, thereby recording the state of the Christmas tree lowering model 6 in the test water tank 1, that is, photographing a series of images of the Christmas tree lowering model 6 deformed by the wave and current in the test water tank 1, and recording the deformation process of the Christmas tree lowering model 6. Preferably, the Christmas tree lowering model 6 is photographed at a set frequency. The image analysis unit analyzes the image photographed by the digital camera. Preferably, the photographed image is a 256-color black and white image.

[0039] In this embodiment, the deformation and bending degree of the Christmas tree lowering model 6 at different time periods and the final bending state can be recorded by a high-resolution digital camera, so that the lateral displacement of different points of the Christmas tree lowering model 6 can be determined after analyzing the images at a later stage.

[0040] The incandescent lamp provides ambient lighting for shooting with a high-resolution digital camera, making the shooting clearer; the punctuation marks are arranged on the Christmas tree lowering model 6, and a plurality of punctuation marks are arranged on the Christmas tree lowering model 6 to mark different positions of the Christmas tree lowering model 6, so that the deformation of the Christmas tree lowering model 6 can be more easily observed.

[0041] Furthermore, the measuring device 4 also includes a displacement and bending moment measuring module. The displacement and bending moment measuring module includes a displacement and bending moment measuring sensor, and specifically, the displacement and bending moment measuring module includes a resistance strain displacement sensor and a resistance strain moment sensor. The lateral displacement and deformation bending moment of the Christmas tree lowering model 6 caused by the wave and current in the test water tank 1 are obtained by the resistance strain displacement sensor and the resistance strain moment sensor.

[0042] The resistance strain type displacement sensor and the resistance strain type torque sensor are fixed on the surface of the Christmas tree lowering model 6. Preferably, a plurality of the resistance strain type displacement sensors and the resistance strain type torque sensors are arranged at intervals above and below the Christmas tree lowering model 6. The position of the punctuation mark is consistent with the position of the sensor.

[0043] Furthermore, in this embodiment, the Christmas tree lowering model 6 can be a drill string model. The drill string is a key part that is easily affected during the lowering of the Christmas tree. Therefore, the Christmas tree is simplified by using the drill string model to better simulate the lowering process of the Christmas tree. The top of the drill string is fixed on the auxiliary frame to ensure that the top of the drill string will not move when it is affected by waves and currents. The resistance strain type displacement sensor and the resistance strain type torque sensor are fixedly arranged on the surface of the drill string model. The Christmas tree lowering model 6 is similar to the prototype Christmas tree, and the Christmas tree lowering model 6 is obtained from the prototype Christmas tree according to the similarity theory.

[0044] like Figure 2 The figure shows a schematic diagram of the structure of a Christmas tree lowering model 6, on which a plurality of the resistive strain type displacement sensors and resistive strain type torque sensors are arranged at intervals to form a plurality of measuring points. Preferably, at least one measuring point is set at each of the two ends of the length direction of the Christmas tree lowering model 6 and one measuring point is set between the two ends of the length square of the Christmas tree lowering model 6, that is, at least three measuring points are set along the length direction of the Christmas tree lowering model 6. Figure 2 In the illustrated Christmas tree lowering model 6, four measuring points, namely measuring point 1, measuring point 2, measuring point 3 and measuring point 4, are set, and the four measuring points are evenly arranged, wherein measuring point 1 is located at the top of the Christmas tree lowering model 6, measuring point 4 is located at the bottom of the Christmas tree lowering model 6, and measuring points 2 and 3 are located in the middle of the Christmas tree lowering model 6. The number and positions of the measuring points can be adjusted according to the length of the Christmas tree lowering model 6, and this embodiment does not limit this.

[0045] The data processing device 5 is used to process and analyze the state data measured by the measuring device 4, determine the relationship between the state data of the Christmas tree lowering model 6 and the water environment, and thus obtain the Christmas tree lowering simulation result. Further, the lateral displacement data and lateral bending moment data of the Christmas tree lowering model 6 measured by the measuring device 4 are analyzed to obtain the interference result of the water body on the Christmas tree lowering model 6 during the lowering process, and evaluate the influence of different parameter wave currents on the Christmas tree lowering model 6.

[0046] In this embodiment, the ocean is simulated by a test water tank 1 containing water, and after the Christmas tree lowering model 6 is lowered into the water body of the test water tank 1, the wave-making device 2 and the flow-making device 3 are used to generate wave currents in the test water tank 1, and the wave currents act on the Christmas tree lowering model 6 in the test water tank 1, causing the Christmas tree lowering model 6 to deform and displace laterally. The measuring device 4 collects the lateral displacement data and lateral bending moment data of the deformation of the Christmas tree lowering model 6, and transmits the lateral displacement data and the lateral bending moment data to the data processing device 5 for analysis and processing, so as to evaluate the influence of different wave and current environments on the Christmas tree lowering model 6, thereby helping to understand the influence of different wave and current parameters on the lowering process of the Christmas tree lowering model 6.

[0047] The deepwater Christmas tree lowering simulation system of the present embodiment is controllable as a whole. The test water tank 1 can provide a stable test environment, and can adjust parameters such as wave height, period and water flow velocity during the test to evaluate their influence on the lowering of the Christmas tree lowering model 6. The simulation system is reasonably designed and can reduce the cost of the Christmas tree lowering test.

[0048] Embodiment 2 As a specific embodiment of the present invention, the present invention provides a deepwater Christmas tree lowering simulation method, using the simulation system described in the first embodiment to simulate the deepwater Christmas tree lowering process, referring to Figure 3 , the specific steps are as follows: S1. Acquire the Christmas tree lowering model data, and prepare the Christmas tree lowering model according to the Christmas tree lowering model data. In this embodiment, the size of the test water tank 1 is 62×2.0×2.0 m. Therefore, when determining the Christmas tree lowering model data, the test water tank 1 needs to be taken into consideration so that the Christmas tree lowering model 6 prepared according to the Christmas tree lowering model data can complete the target test in the test water tank 1.

[0049] In a specific example, the Christmas tree lowering model 6 adopts a drill string model. Specifically, the drill string model is a hollow cylinder with an outer diameter of 14 mm and an inner diameter of 7 mm, made of organic glass, and weighs 5 kg. In other feasible embodiments, the Christmas tree lowering model 6 may also be of other specifications. This embodiment is only described with the above-mentioned Christmas tree lowering model data.

[0050] Further, in a feasible embodiment, the Christmas tree lowering model data is obtained based on the deformation model and according to the gravity similarity criterion. For wave motion, gravity is the main force. When gravity is the main force, the gravity scale is equal to the inertia force scale:

[0051] If expressed in scale, then:

[0052] Will Substitute the above formula, sort it out and transform it, and we get:

[0053] In the formula, is the water flow velocity; is the acceleration due to gravity; is the characteristic length; is the Froude number.

[0054] In this feasible embodiment, according to the gravity similarity criterion, the proportional conversion relationship of the relevant physical quantities is shown in Table 1.

[0055]

[0056] In this feasible embodiment, due to the limitation of the depth of the test tank 1, a deformed model with inconsistent vertical and horizontal scales is adopted, and the need to eliminate waves to make the test results more accurate is considered. .

[0057] In this embodiment, the similarity relationship is shown in Table 2.

[0058] Table 2 Similarity relationship

[0059] The specifications of the drill string model are obtained by scaling down the theoretical calculation data. In theory, the drill string outer diameter is 139.7 mm, the inner diameter is 118.62 mm, and the mass is 30,000 kg. The actual lowering drill string is made of steel. The theoretical value is the data corresponding to the prototype of the Christmas tree lowering model 6. Specifically, the physical quantities in the theoretical analysis and the physical quantities in the model test correspond to each other as shown in Table 3, where the outer diameter of the drill string of the Christmas tree lowering model 6 in the simulation experiment is 1 / 10 of the theoretical value, and the inner diameter is 1 / 17 of the theoretical value.

[0060] Table 3 Comparison of physical quantities in theoretical analysis and model test

[0061] Of course, in other feasible embodiments, the acquisition of the Christmas tree lowering model data may also be based on other methods, and finally the Christmas tree lowering model 6 similar to the Christmas tree prototype is obtained.

[0062] S2. Lowering the Christmas tree lowering model into a test water tank, and performing wave and flow generation in the test water tank to perform a simulation test on the Christmas tree lowering model. Before lowering the Christmas tree lowering model 6 into the test water tank 1, the test wave and current parameters are first determined. After that, the Christmas tree lowering model 6 is lowered, and according to the determined test wave and current parameters, the flow-generating device 2 and the measuring device 3 are started to generate waves and currents in the test water tank 1, so that waves and currents are formed in the test water tank 1, and a simulation test is performed.

[0063] Specifically, in a feasible embodiment, when the working water depth of the wave maker is 70cm, the regular wave height reaches 30cm in the optimal wave height period matching area of ​​not less than 1.0 second span; the wave making period range is 0.3-2.5s, and the reflection after wave elimination is not higher than 15%, ensuring that the wave making accuracy meets the set requirements. Preferably, the power of the flow making device 3 is 55kw, and the flow rate of the generated water flow is 1260 m 3 / h, the flow rate control error is ±5%.

[0064] In a feasible embodiment, a wave and current situation in a specific real ocean environment is simulated: wave height 8m, period 10s, sea surface current speed 1.5m / s. In this embodiment, considering the length scale of 100 and The test was carried out with waves of 0.08m in height, 0.6s in period and a flow velocity of 0.26m / s.

[0065] Furthermore, the wave-making device 2 and the flow-making device 3 are used to form waves and flows with different wave heights, periods and water flow velocities in the test water tank 1, and a simulation test is performed on the lowering of the Christmas tree lowering model 6 under different waves and flows.

[0066] Furthermore, in order to test the interference conditions of the Christmas tree lowering model 6 under different wave heights, periods and water flow velocities, wave and current combinations with different wave heights, periods and water flow velocities are used for testing.

[0067] Specifically, the wave height ranges from 0.08m to 0.12m, the period is from 0.5s to 1.0s, and the water flow velocity is from 0.25m / s to 0.35m / s. Preferably, the wave height is 0.08m, 0.10m, and 0.12m, the period is 0.5s, 0.8s, and 1s, and the water flow velocity is 0.25m / s, 0.30m / s, and 0.35m / s.

[0068] Furthermore, during the test, the wave current was loaded step by step. Before the formal loading, a preload test was carried out to check the working status of different devices and ignore the influence of various nonlinear initial factors.

[0069] S3. Measure the status data of the Christmas tree lowering model during the simulation test, and analyze the influence of the water body on the Christmas tree lowering model according to the status data. The state data of the Christmas tree lowering model 6 in the test water tank 1 caused by the wave current is collected by the measuring device 4. Specifically, the state data includes the lateral displacement data and lateral bending moment data of the Christmas tree lowering model 6. The lowering conditions of the Christmas tree lowering model 6 under different wave currents are measured to obtain the changes in the state of the Christmas tree lowering model 6 caused by the wave current. After the lateral displacement data and lateral bending moment data of the Christmas tree lowering model 6 are obtained by the measuring device 4, they can be compared with the set threshold data to determine whether the influence of the wave current on the Christmas tree lowering model 6 is within the set range.

[0070] Since the environment in the test water tank 1 can be controlled, the Christmas tree lowering simulation under the same wave and current parameters can be performed multiple times, and the results obtained from the respective measurements can be averaged, thereby avoiding the deviation caused by only one measurement.

[0071] The data processing device 5 is used to analyze the measured status data of the Christmas tree lowering model 6.

[0072] Table 4 shows the lateral displacement data of the deformation of the Christmas tree lowering model 6 measured at each measuring point under the action of waves and currents of different wave heights and different periods at a water flow velocity of 0.25 m / s, which is used to evaluate the influence of wave height and period on the lateral displacement of the Christmas tree lowering model 6 under the condition of a constant water flow velocity. Among them, measuring point 1 is located on the water surface, simulating the sea level position.

[0073]

[0074] It can be concluded from Table 4 that the wave height in the test water tank 1 has almost no effect on the lateral displacement of the Christmas tree lowering model 6 measured at each measuring point, and the period has little effect on the lateral displacement of the Christmas tree lowering model 6 measured at each measuring point. As the wave period increases, the displacement of each measuring point decreases slightly, but the maximum displacement value is only 0.03 cm at different periods and wave heights.

[0075] Table 5 shows the lateral displacement data of the Christmas tree lowering model 6 measured at various measuring points at different periods and different water flow velocities when the wave height is 0.08 m, which is used to evaluate the influence of period and water flow velocity on the lateral displacement of the Christmas tree lowering model 6 when the wave height is constant.

[0076]

[0077] It can be concluded from Table 5 that the period has little effect on the lateral displacement of the Christmas tree lowering model 6 measured at each measuring point, but the simulated water flow velocity has a greater effect on the lateral displacement of each measuring point. Under the same period, as the simulated water flow velocity increases, the displacement of the same measuring point increases. When the period is 0.5s, the displacement of measuring point 5 when the water flow velocity is 0.35m / s increases by 29% compared with the displacement when the water flow velocity is 0.25m / s. This shows that the water flow velocity has a greater effect on the mechanical strength of the lowered Christmas tree lowering model 6.

[0078] As the water depth increases (from measuring point 1 to measuring point 5), the lateral displacement of the Christmas tree lowering model 6 under different wave heights and different water flow velocities increases, and the lateral displacement at the bottom of the Christmas tree lowering model 6 reaches 2 cm. The minimum displacement value is 0 and the maximum value is 0.68 cm under different periods and water flow velocities.

[0079] Table 6 shows the transverse bending moment data of the Christmas tree lowering model 6 measured at each measuring point under the action of waves and currents of different wave heights and different periods at a water flow velocity of 0.25 m / s, which is used to evaluate the influence of wave height and period on the transverse bending moment of the Christmas tree lowering model 6 under the condition of a constant water flow velocity.

[0080]

[0081] It can be seen from Table 6 that the wave period and wave height have little effect on the bending moment of measuring points 3, 4 and 5, but have a greater effect on the bending moment of measuring points 1 and 2. Under the 0.5s period, the lateral bending moment of measuring point 1 at a wave height of 0.12m is doubled compared with that at a wave height of 0.08m. Under the wave height of 0.08m, the lateral bending moment of measuring point 1 at a period of 0.5s is also increased by 36% compared with that at a period of 1.0s. This shows that the wave load has no effect on the lateral bending moment of the lowered Christmas tree model 6 at a certain depth, but has a great effect on the lateral bending moment of the Christmas tree model 6 near the water surface. The minimum value of the lateral bending moment is 0 at different periods and wave heights, and the maximum value is 5.01N⋅cm.

[0082] Table 7 shows the transverse bending moment data of the Christmas tree lowering model 6 measured at various measuring points at different periods and different water flow velocities when the wave height is 0.08 m, which is used to evaluate the influence of period and water flow velocity on the transverse bending moment of the Christmas tree lowering model 6 when the wave height is constant.

[0083]

[0084] It can be seen from Table 7 that the water flow velocity has a great influence on the transverse bending moment of each measuring point. The minimum value of the change in the transverse bending moment value at different cycles and water flow velocities is 0, and the maximum value is 1.62 N⋅cm. When the cycle is 0.5s, the transverse bending moment of measuring point 1 increases by about 32% with the increase of water flow velocity. The transverse bending moment of the Christmas tree lowering model 6 gradually decreases with the increase of water depth and is the largest at the water surface.

[0085] By means of the deepwater Christmas tree lowering simulation method of the present embodiment, the interference degree of wave height, period and water flow velocity on the Christmas tree lowering model 6 can be obtained, thereby guiding the Christmas tree lowering operation in a real deepwater environment to ensure the stability and safety of the Christmas tree lowering.

[0086] Furthermore, the state data of the Christmas tree lowering model 6 measured by the measuring device 4 in the simulation test under the influence of the wave flow in the test water tank 1 is compared with the numerical calculation result after similar conversion to verify the consistency. Among them, the numerical calculation result is obtained by solving the theoretical model of the drill pipe. This embodiment only illustrates the numerical calculation, and those skilled in the art can also use the existing methods in the prior art to perform numerical calculation.

[0087] In a feasible embodiment, since the deepwater Christmas tree is subjected to vertical and lateral reaction forces at the bottom joint of the drill string, the gravity of the Christmas tree and the lowering tool, the lateral wave and current force acting on the deepwater Christmas tree, the buoyancy of seawater during the lowering process, the hydrostatic pressure, and the force of the guide rope, etc., among the external forces on the Christmas tree, the vertical and lateral reaction forces at the bottom joint of the drill string are the key points to be solved. By determining the unit weight, effective tension, wave force and current force of the drill string, introducing the analysis model of the external load of the ocean current and waves on the marine engineering structure in the environmental load calculation analysis, establishing the differential equations and boundary conditions for lowering the drill string, and numerically solving the mechanical model of the drill string, the vertical and lateral reaction forces at the bottom joint of the drill string can be solved conveniently and quickly; then the comprehensive external loads on the deepwater Christmas tree when it is lowered to different water depths and different areas are gradually analyzed, a group of comprehensive analysis differential equations for the deepwater Christmas tree lowering process is established, and boundary conditions and continuity conditions are established, and finally the mechanical analysis numerical solution of the deepwater Christmas tree lowering process is realized. The forces on the drill string during the lowering of the deepwater Christmas tree are relatively complex. In order to facilitate analysis and research, the following assumptions are made in the theory: (1) The material of the drill string is uniform and isotropic. It is always within the linear elastic range during movement and deformation, and its stiffness remains unchanged.

[0088] (2) Since the ratio of the diameter to the length of the drill string is extremely small, it mainly bears lateral loads and its deformation is mainly bending. Therefore, the drill string can be treated as a beam for mechanical analysis.

[0089] (3) The movement of ocean currents, waves and drill string is in the same plane, and the lift of ocean currents is not considered.

[0090] (4) It is assumed that the deformation of the drill string micro-segment is small, and furthermore, it is assumed that the deformation angle is also small.

[0091] (5) Applying the small deformation beam theory, therefore .

[0092] Due to the complex effect of ocean load on the drill string, the finite difference method is used to divide the lowered drill string into n parts. Each section is divided into equal segments with a segment length of h. The top node of the string is set to 0, and the bottom node of the string is n. The two ends of the string are extended and virtual nodes n-1, n-2 and n+1, n+2 are set. Figure 4 shown.

[0093] ; ; ; ; set up , the above formula is discretized into: (1)

[0094] Drill string top fixed constraint: , (2) Drill string end free: (3) Equation (1) and boundary conditions (2) and (3) form (n+5) equations, which can be used to calculate the lateral displacements of (n+5) nodes. Since the above linear equations belong to a large sparse matrix equation system (large order, but with many zero elements), the column pivot elimination method can be further used to solve the strip equation system.

[0095] The lateral displacement data and lateral bending moment data of the Christmas tree lowering model 6 at different water flow velocities were measured and similarly converted. After conversion, the comparison with the numerical calculation is as follows: Figure 5 , Figure 6 shown.

[0096] from Figure 5 and Figure 6It can be seen that when the ocean current speed is 0.5m / s, 1.0m / s or 1.5m / s, the experimental data of the lateral displacement and lateral bending moment of the Christmas tree are smaller than the numerical calculation results, with an error of nearly 10%. The specific reason may be that the numerical calculation makes assumptions and simplifications, which leads to deviations from the actual test.

[0097] However, similar model tests show that the lateral displacement and lateral bending moment of the drill string of the oil tree are consistent with the increase of seawater depth under the action of ocean current force. Figure 5 and Figure 6 It can be obtained that with the increase of ocean current force (ocean current velocity), the lateral displacement and lateral bending moment of the drill string of the Christmas tree at the same seawater depth both increase; under the action of the same ocean current force (ocean current velocity), with the increase of seawater depth, the lateral displacement increases and the lateral bending moment decreases, and the lateral bending moment is the largest at the fixed end on the sea surface.

[0098] By means of the deepwater Christmas tree lowering simulation method provided in this embodiment, the influence of different water parameters on the Christmas tree lowering model 6 can be obtained to better guide the design of the Christmas tree, thereby ensuring the stability and safety of the Christmas tree lowering.

[0099] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A deepwater Christmas tree lowering simulation system, characterized in that: The system comprises a test water tank (1), a wave-making device (2), a flow-making device (3), a measuring device (4), a data processing device (5), and a Christmas tree lowering model (6) that can be lowered into the test water tank (1); The test water tank (1) is used to store test water and provide a place required for the test, wherein the test water tank (1) simulates a marine environment, and the water in the test water tank (1) simulates seawater; The wave-making device (2) is used to generate waves in the test water tank (1) to disturb the Christmas tree lowering model (6) lowered in the test water tank (1); The flow generating device (3) is used to generate a water flow with a set flow rate in the test water tank (1) to disturb the Christmas tree lowering model (6) lowered in the test water tank (1); The measuring device (4) is used to measure the deformation state of the Christmas tree lowering model (6) lowered into the test water tank (1) due to the influence of waves and water flow, so as to obtain state data of the Christmas tree lowering model (6); The data processing device (5) is used to process and analyze the status data of the Christmas tree lowering model (6) obtained by the measurement device (4) to determine the degree of influence of waves and water flow on the Christmas tree lowering model (6).

2. The deepwater Christmas tree lowering simulation system according to claim 1, characterized in that: The wave-making device (2) comprises a wave maker and a wave breaker, wherein the wave maker is used to form waves in the test water tank (1), and the wave breaker is used to eliminate waves generated by reflection from the wall of the test water tank (1).

3. The deepwater Christmas tree lowering simulation system according to claim 1, characterized in that: The Christmas tree lowering model (6) is a drill string.

4. The deepwater Christmas tree lowering simulation system according to claim 1, characterized in that: The test water tank (1) is an open water tank.

5. A method for simulating the lowering of a deepwater Christmas tree, using the system according to any one of claims 1 to 4, characterized in that: The method comprises: Acquiring Christmas tree lowering model data, and preparing a Christmas tree lowering model according to the Christmas tree lowering model data; Lowering the Christmas tree lowering model into a test water tank, and performing wave and flow generation in the test water tank to perform a simulation test on the Christmas tree lowering model; The state data of the Christmas tree lowering model during the simulation test is measured, and the influence of the water body on the Christmas tree lowering model is analyzed according to the state data.

6. The deepwater Christmas tree lowering simulation method according to claim 5, characterized in that: The obtaining of the Christmas tree lowering model data and preparing the Christmas tree lowering model according to the Christmas tree lowering model data includes obtaining the Christmas tree lowering model data based on a deformation model and according to a gravity similarity principle.

7. The deepwater Christmas tree lowering simulation method according to claim 5, characterized in that: The step of lowering the Christmas tree lowering model into a test water tank and generating waves and currents in the test water tank to perform a simulation test on the Christmas tree lowering model includes utilizing the wave generating device and the current generating device to form different combinations of wave heights, periods and water flow velocities, and performing the simulation test under the different combinations of wave heights, periods and water flow velocities.

8. The deepwater Christmas tree lowering simulation method according to claim 7, characterized in that: The wave height range is 0.08m-0.12m, the period is 0.5s-1.0s, and the water flow velocity is 0.25m / s-0.35m / s.

9. The deepwater Christmas tree lowering simulation method according to claim 5, characterized in that: Measuring the status data of the Christmas tree lowering model during the simulation test and analyzing the influence of water on the Christmas tree lowering model according to the status data includes measuring lateral displacement data and lateral bending moment data of the Christmas tree lowering model, wherein the lateral displacement data and lateral bending moment data are measured by a displacement and bending moment measurement module fixed on the Christmas tree lowering model.

10. The deepwater Christmas tree lowering simulation method according to claim 9, characterized in that: The displacement and bending moment measurement modules are arranged in plurality on the Christmas tree lowering model at intervals along the water depth direction.

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