Method and device for calculating ultrahigh-pressure well closing water hammer pressure of ultra-deep well containing sulfur precipitation

Abstract

The invention provides a method and a device for calculating ultrahigh-pressure well closing water hammer pressure of an ultra-deep well containing sulfur precipitation. The method comprises the following steps: determining the precipitation amount of elemental sulfur in a shaft based on a dissolution and precipitation physical model of sulfur in the shaft and natural gas parameters of the shaft; determining the critical flow velocity of the elemental sulfur in the shaft based on the critical flow velocity calculation model of the elemental sulfur and the precipitation amount of the elemental sulfur in the shaft; when the air phase flow velocity of the well annulus is greater than the critical flow velocity of elemental sulfur in the shaft, establishing a well shut-in water hammer wave propagation physical model based on the sulfur-containing precipitation water hammer wave velocity equation and related parameters of the shaft, and performing an experiment through the well shut-in water hammer wave propagation physical model to obtain well shut-in water hammer wave propagation characteristics; a well shut-in water hammer pressure calculation model is established based on the well shut-in water hammer wave propagation characteristics, the hard well shut-in water hammer pressure is obtained through the well shut-in water hammer pressure calculation model and the wellbore parameters before hard well shut-in, and the well shut-in water hammer pressure calculation model is used for representing the corresponding relation between the water hammer pressure and the wellbore parameters. The prediction accuracy of the water hammer pressure can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas well engineering, and particularly relates to a method and device for calculating water hammer pressure of ultra-high pressure well closure of an ultra-deep well with sulfur precipitation, computer equipment, a computer readable storage medium, and a computer program product. BACKGROUND

[0002] In the process of controlling overflow and blowout, emergency well closure operation is the primary measure. Emergency well closure operation includes hard well closure. The so-called hard well closure is a well closure method of directly closing the wellhead blowout preventer under the condition that the surface choke manifold is closed. The well closure procedure of hard well closure is simple, and more formation fluid invasion into the wellbore can be avoided, but the blowout preventer combination needs to withstand strong well closure water hammer pressure during well closure. If the water hammer pressure can be calculated before hard well closure, and the corresponding safety measures are designed according to the water hammer pressure, the safety of drilling operations can be effectively guaranteed, and the risk of blowout and other accidents can be reduced.

[0003] At present, for the calculation of water hammer pressure during hard well closure, the gas-liquid two-phase flow is mainly taken as the water hammer wave propagation medium during hard well closure, and the water hammer pressure is theoretically analyzed and calculated according to different gas invasion degrees and different flow patterns.

[0004] However, in deep wells (well depth greater than 6000 meters), due to insufficient research conditions of deep formations and slow progress of ultra-deep wells (well depth greater than 8000 meters), it is impossible to make a reasonable analysis and calculation of the ultra-high pressure (pressure greater than 120 MPa) well closure water hammer pressure of the ultra-deep well, thereby reducing the accuracy of the calculation of the ultra-high pressure well closure water hammer pressure of the ultra-deep well. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a method and device for calculating water hammer pressure of ultra-high pressure well closure of an ultra-deep well with sulfur precipitation, computer equipment, a computer readable storage medium, and a computer program product, so as to improve the accuracy of the calculation of the ultra-high pressure well closure water hammer pressure of the ultra-deep well.

[0006] To solve the above technical problems, the embodiments of the present application provide the following technical solutions: The first aspect of the present application provides a method for calculating the water hammer pressure of a super-high pressure well shut-in in a super-deep well with sulfur precipitation, which comprises: determining the amount of sulfur precipitation in the wellbore based on a sulfur dissolution and precipitation physical model in the wellbore and wellbore natural gas parameters, wherein the sulfur dissolution and precipitation physical model in the wellbore is established based on the physical and chemical conversion characteristics of sulfur entering the wellbore, and is used to represent the corresponding relationship between the critical flow velocity of sulfur and the amount of sulfur precipitation in the wellbore; determining the critical flow velocity of sulfur in the wellbore based on a critical flow velocity calculation model of sulfur and the amount of sulfur precipitation in the wellbore, wherein the critical flow velocity calculation model of sulfur is established based on the movement of sulfur in gas-liquid two-phase flow using two-phase flow theory, and is used to represent the corresponding relationship between the critical flow velocity of sulfur and the amount of sulfur precipitation in the wellbore; when the annulus gas flow velocity is greater than the critical flow velocity of sulfur in the wellbore, establishing a shut-in water hammer wave propagation physical model based on a water hammer wave velocity equation with sulfur precipitation and wellbore related parameters, and obtaining the propagation characteristics of the shut-in water hammer wave through the shut-in water hammer wave propagation physical model, wherein the water hammer wave velocity equation with sulfur precipitation is derived based on the wellbore pressure distribution of a sulfur-containing gas well and the macroscopic calculation equation of the wellbore pressure with sulfur precipitation; establishing a shut-in water hammer pressure calculation model based on the shut-in water hammer wave propagation characteristics, and obtaining the hard shut-in water hammer pressure through the shut-in water hammer pressure calculation model and the wellbore parameters before hard shut-in, wherein the shut-in water hammer pressure calculation model is used to represent the corresponding relationship between the water hammer pressure and the wellbore parameters.

[0007] Compared with the prior art, the method for calculating the water hammer pressure of a super-high pressure well shut-in in a super-deep well with sulfur precipitation provided by the first aspect of the present application can accurately describe the conversion process of sulfur between the formation and the wellbore, including dissolution, precipitation, phase change, etc., which provides a basis for subsequent wellbore pressure and water hammer pressure calculation. The calculation of the critical suspended flow velocity helps to determine the migration state of sulfur in the wellbore, thereby predicting the flow characteristics of the fluid in the wellbore, and further providing a basis for wellbore pressure calculation. The derived numerical calculation expression of the wellbore pressure distribution of a high-sulfur gas well can consider the influence of sulfur on the wellbore pressure, improve the accuracy of the calculation, and help to more accurately predict the wellbore pressure distribution. The establishment of the water hammer wave velocity equation with sulfur precipitation under super-high pressure conditions can describe the propagation characteristics of the water hammer wave when the well is shut-in under super-high pressure conditions, which provides an important parameter for predicting the water hammer pressure. The establishment of the shut-in water hammer wave propagation physical model can analyze the propagation characteristics of the shut-in water hammer wave, such as wave velocity, propagation direction, pressure change, etc., which provides a basis for predicting the pressure change in the wellbore. Finally, the establishment of the shut-in water hammer pressure calculation model based on the shut-in water hammer wave propagation characteristics can predict the water hammer pressure change rule under the condition of multiphase flow, thereby improving the prediction accuracy of the water hammer pressure during the shut-in process of a deep well with sulfur, providing support for the design and safety evaluation of the wellhead device, and ensuring the safety and efficiency of deep well operations, and reducing the risk of blowout accidents.

[0008] The second aspect of the present application provides a device for calculating the water hammer pressure of a super-deep well with sulfur precipitation under ultra-high pressure, comprising: a precipitation calculation module, configured to determine the amount of sulfur precipitation in the wellbore based on a physical model of sulfur dissolution and precipitation in the wellbore and wellbore natural gas parameters, the physical model of sulfur dissolution and precipitation in the wellbore being established based on the physical and chemical conversion characteristics of sulfur entering the wellbore, and used to represent the corresponding relationship between the amount of sulfur precipitation in the wellbore and the wellbore natural gas parameters; a flow rate calculation module, configured to determine the critical flow rate of sulfur in the wellbore based on a critical flow rate calculation model of sulfur and the amount of sulfur precipitation in the wellbore, the critical flow rate calculation model of sulfur being established based on the movement of sulfur in gas-liquid two-phase flow using two-phase flow theory, and used to represent the corresponding relationship between the critical flow rate of sulfur in the wellbore and the amount of sulfur precipitation in the wellbore; a feature acquisition module, configured to, when the annulus gas flow rate in the well is greater than the critical flow rate of sulfur in the wellbore, establish a water hammer wave propagation physical model based on a water hammer wave speed equation with sulfur precipitation and wellbore related parameters, and obtain the propagation characteristics of the water hammer wave through experiments on the water hammer wave propagation physical model, the water hammer wave speed equation with sulfur precipitation being derived based on the wellbore pressure distribution of a sulfur-containing gas well and a macroscopic calculation equation of the wellbore pressure with sulfur precipitation; and a pressure calculation module, configured to establish a water hammer pressure calculation model based on the water hammer wave propagation characteristics, and obtain the water hammer pressure before hard well closure through the water hammer pressure calculation model and the wellbore parameters before hard well closure, the water hammer pressure calculation model being used to represent the corresponding relationship between the water hammer pressure and the wellbore parameters.

[0009] The third aspect of the present application provides a computer device, comprising a memory, a processor, and a computer program stored in the memory, the processor executes the computer program to implement the method in the first aspect.

[0010] The fourth aspect of the present application provides a computer readable storage medium having a computer program stored thereon, the computer program is executed by a processor to implement the method in the first aspect.

[0011] The fifth aspect of the present application provides a computer program product comprising a computer program, the computer program is executed by a processor to implement the method in the first aspect.

[0012] The device for calculating the water hammer pressure of a super-deep well with sulfur precipitation under ultra-high pressure provided by the second aspect of the present application, the computer device provided by the third aspect of the present application, the computer readable storage medium provided by the fourth aspect of the present application, and the computer program product provided by the fifth aspect of the present application have the same or similar beneficial effects as the method for calculating the water hammer pressure of a super-deep well with sulfur precipitation under ultra-high pressure provided by the first aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0013] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which a number of embodiments of the present application are shown by way of example, and wherein like reference numerals refer to like elements throughout. In the drawings: Figure 1 Flowchart of the method for calculating the water hammer pressure of the ultra-deep well with high pressure and sulfur precipitation during well closure in the embodiments of the present application Figure One ; Figure 2 Schematic diagram of the reflection and propagation of the water hammer wave and the elastic wave in the embodiments of the present application Figure 3 Flowchart of the method for calculating the water hammer pressure of the ultra-deep well with high pressure and sulfur precipitation during well closure in the embodiments of the present application Figure Two ; Figure 4 Schematic diagram of the wellbore flow during well closure with sulfur precipitation in the embodiments of the present application Figure 5 Schematic diagram of the grid of the common characteristic line method in the embodiments of the present application Figure 6 Schematic diagram of the change of the water hammer wave velocity with the proportion of the sulfur-containing gas phase in the wellbore in the embodiments of the present application Figure 7 Structure schematic diagram of the device for calculating the water hammer pressure of the ultra-deep well with high pressure and sulfur precipitation during well closure in the embodiments of the present application Figure One ; Figure 8 Structure schematic diagram of the device for calculating the water hammer pressure of the ultra-deep well with high pressure and sulfur precipitation during well closure in the embodiments of the present application Figure Two ; Figure 9 Structure schematic diagram of the computer device in the embodiments of the present application. DETAILED DESCRIPTION

[0014] The exemplary embodiments of the present application will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the present application are shown. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0015] It should be noted that the technical terms or scientific terms used in the present application should be understood as the general meaning understood by the skilled person in the field of the present application, unless otherwise specified.

[0016] Currently, due to insufficient research conditions in deep formations and slow progress in ultra-deep well engineering, it is impossible to make a reasonable analysis and calculation of the water hammer pressure during hard shut-in of ultra-deep wells, thus reducing the accuracy of the calculation of the water hammer pressure during hard shut-in of ultra-deep wells.

[0017] In view of this, embodiments of this application provide a method, apparatus, computer equipment, computer-readable storage medium, and computer program product for calculating the shut-in water hammer pressure of ultra-deep wells with sulfur precipitation under ultra-high pressure. By establishing a physical model of the dissolution and precipitation of sulfur in the wellbore, the transformation process of elemental sulfur between the formation and the wellbore can be accurately described. By performing critical suspension velocity calculations, it helps to determine the transport state of elemental sulfur in the wellbore, thereby predicting the flow characteristics of fluids in the wellbore, and deriving a numerical calculation expression for the pressure distribution of high-sulfur gas wells. It can consider the influence of elemental sulfur on wellbore pressure. By establishing an equation for the water hammer wave velocity of sulfur precipitation under ultra-high pressure conditions, it can describe the propagation characteristics of water hammer waves when shutting in sulfur-containing gas wells under ultra-high pressure conditions. Finally, by establishing a shut-in water hammer pressure calculation model based on the propagation characteristics of shut-in water hammer waves, it can predict the water hammer pressure variation law under multiphase flow conditions, achieve accurate determination of water hammer pressure during hard shut-in, and improve the accuracy of shut-in water hammer pressure calculation.

[0018] It should be noted that all components, data, and related processing methods involved in this application are authorized by the user or fully authorized by all parties, and the collection, use, and processing of related data comply with the relevant laws, regulations, and standards of the relevant countries and regions.

[0019] First, the method for calculating the shut-in water hammer pressure of ultra-deep wells containing sulfur precipitation, as provided in the embodiments of this application, will be described in detail.

[0020] Figure 1 This is a flowchart illustrating the method for calculating the ultra-high pressure shut-in water hammer pressure in ultra-deep wells containing sulfur precipitation, as described in this application. Figure One See Figure 1 As shown, the method may include: S11: The amount of elemental sulfur released from the wellbore is determined based on the physical model of sulfur dissolution and precipitation in the wellbore and the natural gas parameters in the wellbore. The physical model of sulfur dissolution and precipitation in the wellbore is established based on the physicochemical transformation characteristics of elemental sulfur entering the wellbore and is used to characterize the correspondence between the amount of elemental sulfur released from the wellbore and the natural gas parameters in the wellbore.

[0021] The physical and chemical conversion characteristics of elemental sulfur into the wellbore refer to the changes in the physical state (such as solid, liquid, and gas) and chemical composition (chemical reactions with other substances) of elemental sulfur during the transfer from the formation to the wellbore due to changes in environmental conditions (such as temperature, pressure, and fluid medium), as well as the effects of these changes on the properties of the fluid (such as density, viscosity, and solubility). By theoretically analyzing the phase change rules of elemental sulfur (sulfur yellow) under different temperature and pressure conditions, the possible physical states (solid, liquid, or gas) of elemental sulfur in the wellbore are determined. At the same time, relevant literature and experimental data are collected, especially the conversion data of elemental sulfur under formation conditions mixed with natural gas mixture (especially hydrogen sulfide H2S), to understand the reaction mechanism and rate of hydrogen sulfide converting to elemental sulfur under a preset high temperature and high pressure environment (temperature ≥ 150 ℃ and pressure ≥ 69.8 MPa). The physical and chemical conversion characteristics of elemental sulfur into the wellbore are obtained.

[0022] Here, the preset high temperature and high pressure specifically refer to a temperature of 150 ℃ or higher and a pressure of 69.8 MPa or higher.

[0023] Based on theoretical analysis and data, that is, based on the physical and chemical conversion characteristics of elemental sulfur into the wellbore, a physical model of dissolution and precipitation of elemental sulfur in the wellbore is constructed. In the construction, the decomposition reaction of hydrogen sulfide gas during the temperature and pressure reduction in the wellbore, as well as the catalytic reaction of elemental sulfur with the wellbore wall or other substances (such as iron elements), are considered. At the same time, the solubility parameter of elemental sulfur is also set, which determines the key of whether elemental sulfur precipitates from the gas phase. Using the principle of chemical equilibrium, the functional relationship between the solubility of elemental sulfur in the wellbore and temperature and pressure is derived. At the same time, by considering the actual dissolution state of elemental sulfur in the fluid through physical dissolution equilibrium, a mathematical expression is established to describe the transition conditions between different states of elemental sulfur, that is, the physical model of dissolution and precipitation of sulfur in the wellbore is obtained.

[0024] In order to calculate the water hammer pressure during hard shut-in of the wellbore, the current natural gas parameters of the wellbore need to be substituted into the physical model of dissolution and precipitation of sulfur in the wellbore to calculate the current precipitation amount of elemental sulfur in the wellbore through the model.

[0025] S12: Determine the critical flow velocity of elemental sulfur in the wellbore based on the critical flow velocity calculation model of elemental sulfur and the precipitation amount of elemental sulfur in the wellbore. The critical flow velocity calculation model of elemental sulfur is established based on the two-phase flow theory of the motion of elemental sulfur in gas-liquid two-phase fluid, which is used to represent the corresponding relationship between the critical flow velocity of elemental sulfur in the wellbore and the precipitation amount of elemental sulfur in the wellbore.

[0026] Since most of the sulfur elements entering the wellbore are in the form of compounds, miscible or miscible with other gas-containing fluids in the wellbore, macroscopically, it shows a "dissolution" trend, but part of the sulfur elements will adhere to the well wall in the form of elemental sulfur at the beginning of entering the wellbore, or during the annulus circulation return process, due to the change of temperature and pressure, the dissolved sulfur-containing wellbore fluid will precipitate and settle elemental sulfur. The critical suspension flow rate is used to determine the output, settlement or suspension of elemental sulfur with wellbore fluid. When the annulus gas flow rate is greater than the critical flow rate, the elemental sulfur is carried out of the wellbore by the upward natural gas, when the annulus gas flow rate is equal to the critical flow rate, the elemental sulfur is in a suspended state, and when the annulus gas flow rate is less than the critical flow rate, the elemental sulfur will settle back to the bottom of the well.

[0027] Since the dissolution and precipitation physical model of sulfur in the wellbore considers the influence of temperature and pressure on the phase change of elemental sulfur, as well as the interaction of elemental sulfur with other fluids in the wellbore, by using the established physical model of dissolution and precipitation of sulfur in the wellbore, the amount (mass or volume fraction), density, shape and other key physical parameters of precipitated elemental sulfur under specific working conditions (such as actual temperature, pressure, hydrogen sulfide concentration, etc. in the wellbore) are calculated. Considering the motion of elemental sulfur in gas-liquid two-phase fluid, fluid mechanics theory, especially two-phase flow theory, is used to analyze the motion of elemental sulfur particles in the fluid. The motion equation of elemental sulfur is used, which reflects the action of gravity, buoyancy, inertial force and fluid resistance on elemental sulfur. Since the density of elemental sulfur is different from that of gas, the velocity gradient is formed, which leads to resistance. Combined with the motion equation of elemental sulfur, fluid dynamics principles and fluid resistance equation, the calculation formula of critical flow rate is derived. This usually involves factors such as the density of elemental sulfur, the flow rate of fluid, the viscosity of fluid and the size of flow channel. By substituting the known physical parameters of elemental sulfur and the flow conditions of the wellbore into the calculation formula, the specific value of the critical suspension flow rate is obtained. According to the comparison between the calculated critical flow rate and the actual wellbore fluid circulation return flow rate, the behavior of elemental sulfur in the wellbore is determined. If the flow rate is higher than the critical value, the elemental sulfur is effectively carried upward. If it is equal to or lower than the critical value, it may settle or suspend. This is directly related to the influence of elemental sulfur on the fluid dynamics in the wellbore, and further affects the calculation accuracy of wellbore pressure distribution and water hammer pressure.

[0028] S13: When the annulus gas flow rate is greater than the critical flow rate of elemental sulfur in the wellbore, a shut-in water hammer wave propagation physical model is established based on the sulfur-containing precipitation water hammer wave velocity equation and the relevant parameters of the wellbore, and an experiment is conducted through the shut-in water hammer wave propagation physical model to obtain the shut-in water hammer wave propagation characteristics. The sulfur-containing precipitation water hammer wave velocity equation is derived based on the sulfur-containing gas wellbore pressure distribution and the macroscopic calculation equation of sulfur-containing precipitation in the wellbore.

[0029] Since the present embodiment takes "high-sulfur natural gas" as an example, that is, the sulfur element exists in any section of the entire gas well borehole, the premise of the present step is that the annulus upflow velocity (i.e., the gas phase flow velocity in the well annulus, because the gas well borehole is mostly filled with water gas, and the gas composition has a greater impact, so the gas phase flow velocity is used) is definitely greater than the critical flow velocity of the sulfur element, so only when the gas phase flow velocity in the well annulus is greater than the critical flow velocity, the sulfur element is carried out of the well borehole by the upflowing natural gas, and the present step calculates and derives the sulfur precipitation water hammer velocity equation and establishes the shut-in water hammer wave propagation physical model.

[0030] Since the microscopic mechanical behavior of the sulfur element is nonlinear and the movement characteristics are complex, but from a macroscopic perspective, more is seen as a single process of fluid flow in the well borehole, four reasonable assumptions are made (including that the gas well production process is a stable production with constant production, the flow of gas and sulfur element in the well borehole is one-dimensional flow, all characteristic parameters of gas and sulfur element at any interface in the well borehole are the same, and gas and the outside do not do work on each other). From a macroscopic perspective, the well borehole pressure formed by the gas-liquid multiphase flow in the sulfur-containing well borehole is calculated, and the sulfur precipitation water hammer velocity equation is derived. In the macroscopic calculation equation of the well borehole pressure, the calculation auxiliary parameters (acceleration pressure drop of precipitated sulfur, friction pressure drop, lifting pressure drop, and along-the-way energy loss coefficient) related to the sulfur element are introduced. These data are derived from the numerical simulation of the microscopic dynamics of the sulfur element, and there are corresponding public documents that can be directly obtained.

[0031] After the water hammer velocity is calculated, the dynamic change characteristics of the water hammer pressure can be observed by substituting the well borehole pressure calculation parameters at different times, that is, the water hammer pressure wave is generated by emergency shut-in. Accordingly, the physical characteristics in the shut-in water hammer propagation process are statistically analyzed, laying a theoretical foundation for the final water hammer pressure calculation.

[0032] Based on the sulfur precipitation water hammer velocity equation, the dynamic influence of the sulfur element on the water hammer velocity is considered, and the corresponding variables are integrated into the water hammer wave propagation model. The variables include but are not limited to well borehole size, fluid properties, pressure distribution, sulfur content, etc., which directly affect the propagation characteristics of the water hammer wave. By using fluid mechanics theory and combining the dynamics of the sulfur phase, liquid phase, solid phase, and annulus, a water hammer wave propagation model is established to simulate the propagation process of the shut-in water hammer wave in the well borehole. The propagation state of the water hammer wave at different time points is simulated by using simulation software, the influence of the sulfur element is considered, such as pressure and velocity changes, and the propagation characteristics of the wave are intuitively displayed.

[0033] S14: A shut-in water hammer pressure calculation model is established based on the shut-in water hammer wave propagation characteristics, and the hard shut-in water hammer pressure is obtained through the shut-in water hammer pressure calculation model and the well borehole parameters before hard shut-in. The shut-in water hammer pressure calculation model is used to represent the corresponding relationship between the water hammer pressure and the well borehole parameters.

[0034] Since the water hammer pressure is not a constant value, the actual calculation of the water hammer pressure is the maximum value. Because the shut-in water hammer propagation feature is in the form of wave propagation, the water hammer pressure borne by the wellhead device after emergency shut-in generally presents periodic changes. Figure 2 For the water hammer wave elastic wave superposition reflection propagation schematic diagram in the embodiment of the present application, referring to Figure 2 As shown in the figure, the wave crest and wave trough alternate along the axial direction of the wellbore. The maximum water hammer pressure is related to whether the blowout preventer in the wellhead device can withstand it, and also determines whether the shut-in measure is effective. If the water hammer pressure after shut-in greatly exceeds the upper limit of the pressure that the wellhead device can bear, it is likely to cause the shut-in operation to fail and be ineffective, and to cause serious accidents such as blowout.

[0035] According to the wave propagation characteristics, a shut-in water hammer pressure calculation model is established, and the wellbore parameters before hard shut-in are input into the shut-in water hammer pressure calculation model to obtain the real-time hard shut-in water hammer pressure.

[0036] From the above, the method for calculating the ultra-high pressure shut-in water hammer pressure of the super-deep well with sulfur precipitation provided in the embodiments of the present application can accurately describe the conversion process of sulfur between the formation and the wellbore, including dissolution, precipitation, phase change, etc., by establishing a physical model of sulfur dissolution and precipitation in the wellbore, thereby providing a basis for subsequent wellbore pressure and water hammer pressure calculations. The calculation of the critical suspension flow rate helps to determine the migration state of sulfur in the wellbore, thereby predicting the flow characteristics of the fluid in the wellbore and further providing a basis for wellbore pressure calculation. The derived numerical calculation expression of the wellbore pressure distribution of the high-sulfur gas well can consider the influence of sulfur on the wellbore pressure, improve the accuracy of the calculation, and help to more accurately predict the wellbore pressure distribution. By establishing the water hammer wave velocity equation under the condition of ultra-high pressure with sulfur precipitation, the propagation characteristics of the water hammer wave during the shut-in of the high-sulfur gas well under the condition of ultra-high pressure can be described, thereby providing an important parameter for predicting the water hammer pressure. By establishing a physical model of the propagation of the shut-in water hammer wave, the propagation characteristics of the shut-in water hammer wave, such as wave velocity, propagation direction, and pressure change, are analyzed, thereby providing a basis for predicting the pressure change in the wellbore. Finally, by establishing a shut-in water hammer pressure calculation model based on the propagation characteristics of the shut-in water hammer wave, the water hammer pressure change law under the condition of multiphase flow can be predicted, thereby improving the prediction accuracy of the water hammer pressure during the shut-in process of the deep well with sulfur, providing support for the design and safety evaluation of the wellhead device, and thereby ensuring the safety and efficiency of the deep well operation and reducing the risk of accidents such as blowout.

[0037] Further, as a refinement and extension of the method shown in Figure 1 The embodiments of the present application also provide a method for calculating the ultra-high pressure shut-in water hammer pressure of a super-deep well with sulfur precipitation.

[0038] Figure 3 The flowchart of the method for calculating the ultra-high pressure shut-in water hammer pressure of the super-deep well with sulfur precipitation in the embodiments of the present application is shown inFigure Two Referring to FIG. 1, Figure 3 The method can include: S31: establishing a physical model of dissolution and precipitation of sulfur in the wellbore based on a physical and chemical conversion feature of elemental sulfur entering the wellbore.

[0039] An experiment is designed to simulate the reaction of a natural gas mixture containing hydrogen sulfide under different temperature and pressure conditions, to observe the generation and dissolution behavior of elemental sulfur, to simulate the physical and chemical conversion path of elemental sulfur in the wellbore environment by using molecular simulation software, and to verify the accuracy of the theoretical model. The parameters obtained from the experiment and simulation are integrated into the model, and the dissolution and precipitation process of elemental sulfur is quantified by mathematical formula to obtain a physical model of dissolution and precipitation of sulfur in the wellbore.

[0040] Specifically, step S31 can include: obtaining test parameters including at least generation temperature, generation pressure and solubility from the separation and degradation reaction of the natural gas mixture containing hydrogen sulfide components; determining the physical and chemical conversion path of elemental sulfur entering the wellbore based on the test parameters; and establishing a physical model of dissolution and precipitation of sulfur in the wellbore based on the physical and chemical conversion path and the chemical reaction equilibrium and physical dissolution equilibrium of elemental sulfur in a preset high temperature and high pressure environment, wherein the preset high temperature and high pressure environment is an environment with a temperature ≥ 150 ℃ and a pressure ≥ 69.8 MPa.

[0041] It should be noted that if the elemental sulfur in the formation is to enter the wellbore and undergo phase change, the important intermediate medium in the formation is mostly hydrogen sulfide gas. Therefore, a certain amount of natural gas mixture containing hydrogen sulfide components can be extracted, the separation and degradation reaction of gaseous sulfur hydrogen compounds is simulated by experiment, the pressure and temperature conditions in the test container are adjusted, and test parameter results including at least generation temperature, generation pressure and solubility are obtained. Based on the test parameter results, the physical and chemical conversion path of elemental sulfur entering the wellbore is obtained by using molecular simulation data software processing means.

[0042] There are three physical and chemical conversion paths of elemental sulfur entering the wellbore, which are: (1) The polysulfide generated by the elemental sulfur in the formation and the hydrogen sulfide components in the natural gas mixture undergoes a catalytic thermal degradation reaction with the iron elements in the casing or the iron elements in the formation in the preset high temperature and high pressure environment within 4-6 hours, thereby generating elemental sulfur and adhering to the wellbore; (2) In the well area of carbon dioxide injection drive, the hydrogen sulfide components in the natural gas mixture are also oxidized by carbon dioxide to generate elemental sulfur and adhere to the wellbore, but the required reaction conditions are harsh, so the probability of this path is small; (3) The elemental sulfur has a certain solubility in the natural gas mixture. When the solubility of the elemental sulfur in the natural gas mixture is lower than the maximum solubility of the elemental sulfur, the elemental sulfur is converted from solid to liquid and enters the wellbore along with the formation natural gas in the form of gas-liquid two-phase flow. When the solubility of the elemental sulfur in the natural gas mixture is higher than the maximum solubility, the elemental sulfur is no longer dissolved in the formation natural gas and is carried into the wellbore along with the formation natural gas in the form of liquid droplets or solid particles; The specific derivation process of the dissolution and precipitation physical model of sulfur in the wellbore is as follows: in the solid-liquid conversion state, the density calculation formula of the elemental sulfur is:

[0043] wherein, represents the density of the elemental sulfur in the conversion period, g / m 3 , respectively represent the density calculation parameters of the elemental sulfur, , dimensionless, represents the conversion temperature, K.

[0044] In the solid-liquid conversion state, the flow viscosity calculation formula of the elemental sulfur is:

[0045] wherein, represents the flow viscosity of the elemental sulfur, mPa·s, represents a constant term coefficient of the viscosity formula, represents a first-order term coefficient of the viscosity with respect to temperature, represents a second-order term coefficient of the viscosity with respect to temperature, represents a third-order term coefficient of the viscosity with respect to temperature.

[0046] The physical and chemical conversion path of the elemental sulfur into the wellbore is used to establish the dissolution and precipitation physical model of sulfur in the wellbore. The chemical reaction equilibrium and physical dissolution equilibrium of the elemental sulfur in the preset high-temperature and high-pressure environment are considered. The solubility of the elemental sulfur is solved in sections, and the mathematical expression of the dissolution and precipitation of sulfur in the wellbore is established, as follows: , wherein, represents the solubility of the elemental sulfur, g / m 3 , represents a dissolution coefficient, which is determined by experiment and fitting, dimensionless, represents the proportion of at least the acid gas components including hydrogen sulfide and carbon dioxide in the formation natural gas, %, represents the density of the elemental sulfur in the conversion period, represents the conversion temperature, represents the dynamic precipitation amount of the elemental sulfur, g / m3 , denotes the wellbore natural gas density at the moment when elemental sulfur is not precipitated, g / m 3 , denotes the wellbore natural gas density after 15 minutes of elemental sulfur precipitation, g / m 3 , denotes the constant term coefficient of the viscosity formula, denotes the first-order term coefficient of viscosity with respect to temperature, denotes the second-order term coefficient of viscosity with respect to temperature, denotes the third-order term coefficient of viscosity with respect to temperature.

[0047] By establishing the dissolution and precipitation physical model of sulfur in the wellbore, the behavior of elemental sulfur in the wellbore can be more accurately described, which provides an important basis for predicting the pressure distribution and water hammer pressure in the wellbore.

[0048] S32: determining the amount of elemental sulfur precipitated in the wellbore based on the dissolution and precipitation physical model of sulfur in the wellbore and the wellbore natural gas parameters.

[0049] It should be noted that the dissolution and precipitation physical model of sulfur in the wellbore can be established in advance, and when the water hammer pressure is needed to be calculated, the proportion of each acidic gas component such as hydrogen sulfide in the formation natural gas, the wellbore natural gas density at the moment when elemental sulfur is not precipitated, the wellbore natural gas density after a period of time of elemental sulfur precipitation, etc. can be directly extracted and input into the model to calculate the current amount of elemental sulfur precipitated in the wellbore through the model.

[0050] S33: deriving the critical flow velocity expression of elemental sulfur based on the physical quantities of precipitated elemental sulfur in the dissolution and precipitation physical model.

[0051] Specifically, step S33 can include: determining the motion equation of elemental sulfur based on the migration mode of the physical quantities of precipitated elemental sulfur in the dissolution and precipitation physical model; calculating the critical flow velocity expression of elemental sulfur according to the motion equation and the force condition corresponding to the migration mode, and constructing a critical flow velocity calculation model based on the motion equation of elemental sulfur and the critical flow velocity calculation expression.

[0052] The specific derivation process is as follows: The motion equation of elemental sulfur is:

[0053] The density of elemental sulfur is different from that of gas, resulting in different inertial forces acting on them, causing the flow velocity distribution of elemental sulfur and gas to be inconsistent, and the velocity difference between the two phases produces the flow resistance of elemental sulfur, which is:

[0054] The calculation of the buoyancy and gravity acting on elemental sulfur is:

[0055] The critical flow velocity of elemental sulfur is calculated by moving the terms in the above four formulas:

[0056] wherein, u most Vcrit represents the critical flow velocity of elemental sulfur, Vprec represents the volume of precipitated elemental sulfur, which can be calculated by the precipitation mathematical formula of sulfur in the wellbore, cm 3 , Vr represents the migration velocity of elemental sulfur, m / s, t represents the migration time, s, Vann represents the annulus air phase flow rate, m / s, F represents the flow resistance of elemental sulfur, N, Fbuoy represents the buoyancy, N, Fg represents the gravity, N, g represents the acceleration of gravity, m / s 2 , Cstokes represents the Stokes resistance coefficient, dimensionless, Amax represents the maximum cross-sectional area of elemental sulfur, which is extracted according to the measurement statistics of elemental sulfur precipitated at the wellhead, cm 2 , ρ15 represents the density of natural gas in the wellbore after elemental sulfur has been precipitated for 15 minutes.

[0057] S34: Determine the critical flow velocity of elemental sulfur in the wellbore based on the critical flow velocity calculation model of elemental sulfur and the amount of elemental sulfur precipitated in the wellbore.

[0058] It should be noted that the critical flow velocity calculation model of elemental sulfur can be established in advance. When the shut-in water hammer pressure needs to be calculated, the amount of elemental sulfur precipitated in the wellbore can be directly extracted and input into the model to calculate the current critical flow velocity of elemental sulfur in the wellbore.

[0059] By calculating the critical suspension flow velocity, the behavior of elemental sulfur in the wellbore can be more accurately described, providing an important basis for predicting the pressure distribution and water hammer pressure in the wellbore.

[0060] S35: Derive the numerical calculation expression of the pressure distribution in the wellbore of a high-sulfur gas well based on the law of conservation of energy and the macroscopic kinetic parameters of elemental sulfur.

[0061] Specifically, step S35 can include: when the flow state of the gas in the wellbore and the sulfur element and the production condition of the gas well meet the prerequisite conditions, introducing a calculation auxiliary parameter related to the sulfur element based on the change of the wellbore gas-liquid multiphase flow energy with sulfur element precipitation, complying with the law of conservation of energy, establishing a wellbore pressure macroscopic calculation equation, wherein the prerequisite conditions include that the production process of the gas well is stable production with constant yield, the flow of the gas and the sulfur element in the wellbore is one-dimensional flow, all characteristic parameters of the gas and the sulfur element at any interface of the wellbore are the same, and the gas and the outside do not do work on each other, and the calculation auxiliary parameter includes the accelerated pressure drop of the precipitated sulfur, the friction pressure drop, the lifting pressure drop, and the energy loss coefficient along the way; introducing the solubility of the sulfur element and the change of the volume fraction of the sulfur element in the wellbore caused by the flow rate difference between different phases in the wellbore pressure macroscopic calculation equation, and establishing a numerical calculation expression of the wellbore pressure distribution of the high-sulfur gas well.

[0062] The specific derivation process is as follows: The wellbore pressure distribution of the ultra-deep well is related to the flow state of the high-sulfur natural gas, which depends on the properties of the high-sulfur natural gas, and the properties are affected by high temperature and high pressure conditions. This multi-factor influence leads to the complexity of the actual wellbore pressure calculation process of the high-sulfur gas well. Therefore, based on the traditional calculation method, the solubility of the sulfur element and the change of the volume fraction of the sulfur element in the wellbore caused by the flow rate difference between different phases can be considered to establish a new model for calculating the wellbore pressure of the ultra-deep well with sulfur element precipitation.

[0063] It should be noted that before implementing the wellbore pressure calculation of the ultra-deep well, the following reasonable basic assumptions must be made to ensure that the software calculation results are consistent with the actual situation: (1) The production process of the gas well is stable production with constant yield; (2) The flow of the gas and the sulfur element in the wellbore is one-dimensional flow; (3) All characteristic parameters of the gas and the sulfur element at any interface of the wellbore are the same; (4) The gas and the outside do not do work on each other.

[0064] The kinetic energy change of the liquid, gas and sulfur element in the wellbore, plus the work done to overcome gravity, the viscous resistance of multiphase flow, and the friction resistance, will cause changes in the pressure distribution in the wellbore. Therefore, based on the work done by the wellbore gas-liquid multiphase flow with sulfur element precipitation, the law of conservation of energy is complied with to establish a wellbore pressure macroscopic calculation equation, which is expressed as:

[0065] The accelerated pressure drop caused by the kinetic energy change of the wellbore gas-liquid multiphase flow with sulfur element precipitation is:

[0066] The friction pressure drop of the wellbore gas-liquid multiphase flow with sulfur element precipitation to overcome the resistance is:

[0067] The lifting pressure drop of the gas-liquid multiphase flow in the wellbore containing sulfur precipitation is:

[0068] wherein, P represents the wellbore pressure at any time, MPa, P0 represents the wellbore pressure at the initial time, the pressure drop change at the initial time is 0, MPa, ΔP represents the pressure drop, respectively, the pressure drop of the liquid phase, the gas phase and the precipitated sulfur in the wellbore, MPa, respectively, the accelerating pressure drop of the liquid phase, the gas phase and the precipitated sulfur in the wellbore, MPa, respectively, the friction pressure drop of the liquid phase, the gas phase and the precipitated sulfur in the wellbore, MPa, respectively, the lifting pressure drop of the liquid phase, the gas phase and the precipitated sulfur in the wellbore, MPa, respectively, the viscosity of the liquid phase, the gas phase and the precipitated sulfur in the wellbore, mPa·s, respectively, the density of the liquid phase, the gas phase and the precipitated sulfur in the wellbore, g / m 3 , respectively, the migration velocity of the liquid phase, the gas phase and the precipitated sulfur in the wellbore considering the occurrence of the slip effect, m / s, respectively, the energy loss coefficient of the liquid phase, the gas phase and the precipitated sulfur in the wellbore along the way, dimensionless, L represents the wellbore length, m, V represents the wellbore volume, m 3 , D represents the wellbore cross-sectional diameter, m, g represents the gravitational acceleration, m / s 2 .

[0069] By establishing the numerical calculation expression of the wellbore pressure distribution considering the influence of elemental sulfur, the pressure distribution in the wellbore of the high-sulfur gas well can be more accurately described, which provides an important basis for predicting the pressure distribution and water hammer pressure in the wellbore.

[0070] S36: Based on the wellbore pressure distribution of the high-sulfur gas well, a water hammer wave speed equation under extra-high pressure conditions is established.

[0071] Based on the analysis of the physical phenomena of sulfur element and its influence in the wellbore, the water hammer wave velocity under the condition of ultra-high pressure in the wellbore is calculated and analyzed based on the pressure distribution of the wellbore of the high-sulfur gas well. Combined with the physical definition of the volume change of the wellbore, the corresponding calculation formula of the deformation amount of each part is applied, and the pressure drop in it involves the annular flow rate u. Taking this flow rate physical quantity as the cut-in point, the water hammer wave velocity can be converted, and the water hammer wave velocity is the combined speed of the uphole wellbore fluid at the moment of well shut-in when the wellhead device is impacted and contacted by the gas-liquid multiphase flow in the wellbore. This speed is also the flow rate of the sulfur precipitation fluid at this moment.

[0072] The dissolution and precipitation model of aggregate sulfur in the wellbore, the calculation results of the critical suspended flow rate, and the pressure distribution data, as well as the physical and chemical properties of the wellbore of the high-sulfur gas well. Based on the ultra-high pressure condition, it is assumed that the flow of gas and sulfur element is one-dimensional, the three-dimensional structure influence of the complex fluid in the wellbore is ignored, and it is assumed that the fluid and sulfur element parameters at any point in the gas wellbore are the same, and there is no external work. The flow of multiphase fluid in the wellbore is simplified, the relative flow of sulfur gas phase, liquid phase and solid phase (including sulfur element) is considered, and the axial motion is simplified, and the transverse disturbance amount change is ignored. According to the hard shut-in water hammer process, the closing time of the blowout preventer is ignored, and the instantaneous effect is simplified, the fluid motion caused by the pressure sudden change at the moment of well shut-in is considered, and the water hammer wave propagation model is established. Based on high pressure, the compression deformation of sulfur element, gas phase, liquid phase and solid phase, and the annular expansion deformation are considered. The compression deformation amount expression of each phase is listed, including sulfur element compression, liquid phase compression amount, solid phase compression amount, annular expansion amount, etc. Based on the theory of fluid mechanics, combined with the law of conservation of energy and mass, the characteristics of sulfur-containing phase are considered. And all the above parameters are integrated, the equation of water hammer wave velocity under the condition of ultra-high pressure is derived, considering the compression of sulfur element and fluid, energy loss, pressure change, fluid velocity, etc.

[0073] Specifically, step S36 can include: simplifying the form of multiphase flow motion in the wellbore to axial flow along the wellbore, and analyzing the compression deformation of sulfur gas phase, liquid phase and solid phase under the condition of ultra-high pressure and the expansion deformation of the annulus under the condition of ultra-high pressure, to obtain the compression deformation amount of each phase and the annular expansion deformation amount; adding the compression deformation amount of each phase and the annular expansion deformation amount to obtain the volume change of the wellbore; obtaining the elastic modulus and volume fraction of the sulfur-containing gas phase, liquid phase and solid phase; determining the apparent density of the multiphase fluid in the wellbore at the overflow shut-in water hammer according to the returned drilling fluid before shut-in; in the case of ignoring the dissipation of multiphase fluid, based on the law of conservation of mass and momentum, the elastic modulus and volume fraction of sulfur-containing gas phase, liquid phase and solid phase, the apparent density of multiphase fluid in the wellbore at the overflow shut-in water hammer, and the volume change of the wellbore are introduced into the numerical calculation expression of the pressure distribution of the wellbore of the high-sulfur gas well, and the water hammer wave velocity equation is established.

[0074] The specific derivation process is as follows: Sulfur precipitation is often accompanied by complex gas-liquid-solid three-phase wellbore flow of liquid-gas two-phase separation mixed flow. If the wellbore pressure and the formation pressure are unbalanced at this time, the gas channeling overflow in the wellbore is easily induced. Aiming at the water hammer problem existing during the "hard shut-in" after overflow, the gas invasion in the drilling process is taken as the research object, the multi-phase flow movement form in the wellbore is simplified as "axial flow along the wellbore", the blowout preventer closing time is ignored, the wellbore pressure macroscopic calculation equation of sulfur precipitation is introduced, and the water hammer wave speed equation under the condition of ultra-high pressure is established.

[0075] The sulfur-containing gas phase compression deformation, liquid phase compression deformation, solid phase compression deformation and annulus expansion deformation are comprehensively considered, the water hammer wave speed equation is established based on the two laws of fluid mass conservation and momentum conservation, and the multi-phase fluid dissipation is ignored.

[0076] Figure 4 The wellbore flow schematic diagram during sulfur precipitation shut-in in the embodiment of the application is shown in the figure. The annulus fluid flow speed in the normal drilling process is , the drilling fluid flow speed after shut-in is , the water hammer wave speed is , the annulus cross-sectional area is , the wellbore height of annulus expansion is .

[0077] The sulfur-containing gas phase compression deformation involved is:

[0078] The liquid phase compression deformation involved is:

[0079] The solid phase compression deformation involved is:

[0080] The annulus expansion deformation involved is:

[0081] The wellbore volume change is equal to the sum of the sulfur-containing gas phase compression deformation, the liquid phase compression deformation, the solid phase compression deformation and the annulus expansion deformation within a certain time, and since the multi-phase fluid dissipation does not occur, the sum of the proportions of the gas, liquid and solid phases in the wellbore is 100%, and the apparent density The water hammer wave speed equation is established as follows:

[0082] wherein, represents the water hammer wave speed, represents the sulfur-containing gas phase compression deformation, represents the pressure drop, represents the liquid phase compression deformation amount, represents the solid phase compression deformation amount, represents the annulus control expansion deformation amount, represents the annulus cross-sectional area, represents the wellbore annulus sulfur-containing gas phase component, represents the wellbore annulus sulfur-containing gas phase elastic modulus, MPa, represents the wellbore annulus liquid phase component, represents the wellbore annulus liquid phase elastic modulus, MPa, represents the wellbore annulus solid phase component, represents the wellbore annulus solid phase elastic modulus, MPa, represents the wellbore elastic modulus, MPa, represents the wellbore height where annulus expansion occurs, m, represents the time difference, s, represents the wellbore cross-sectional diameter size, represents the annulus expansion cross-sectional radial deformation amount, represents the apparent density of the wellbore multiphase fluid at the overflow shut-in water hammer time, which can be determined from the drilling fluid returned before shut-in, g / m 3 .

[0083] It should be noted that the water hammer wave speed equation can be established in advance, and can be directly extracted for use when the shut-in water hammer pressure needs to be calculated.

[0084] Simplifying the form of multiphase flow in the wellbore to axial flow along the wellbore helps to reduce the complexity of the calculation, making the model more practical and easy to operate. By analyzing the compression deformation of the sulfur-containing gas phase, liquid phase and solid phase under ultra-high pressure conditions and the expansion deformation of the wellbore annulus under ultra-high pressure conditions, the physical behavior of the fluid in the wellbore can be more accurately described. The elastic modulus and volume fraction of the sulfur-containing gas phase, liquid phase and solid phase can reflect the physical properties of each phase, providing the necessary parameters for the water hammer wave speed equation. Combined with the apparent density of the wellbore multiphase fluid at the overflow shut-in water hammer time, and ignoring the dissipation of the multiphase fluid, the elastic modulus and volume fraction of the sulfur-containing gas phase, liquid phase and solid phase, the apparent density of the wellbore multiphase fluid at the overflow shut-in water hammer time, and the volume change of the wellbore are introduced to establish the water hammer wave speed equation based on the law of conservation of mass and momentum. The equation can accurately describe the propagation characteristics of the water hammer wave at the shut-in time of the sulfur-containing gas well under ultra-high pressure conditions.

[0085] S37: When the well annulus gas flow rate is greater than the critical flow rate of elemental sulfur in the wellbore, a shut-in water hammer wave propagation physical model is established based on the sulfur precipitation water hammer wave speed equation and the wellbore related parameters, and an experiment is conducted through the shut-in water hammer wave propagation physical model to obtain the shut-in water hammer wave propagation characteristics.

[0086] Specifically, step S37 can include: based on the sulfur precipitation water shock wave speed equation, integrating the dynamic influence variable of elemental sulfur on the water shock wave speed into the water sulfur precipitation water shock wave speed equation, and using fluid mechanics theory, combining sulfur phase, liquid phase, solid phase and annulus dynamics, to establish a water shock wave propagation model, the dynamic influence variable includes wellbore size, fluid properties, pressure distribution, elemental sulfur content; based on the shut-in water shock wave propagation physical model, the propagation process of the shut-in water shock wave in the wellbore is simulated by using simulation software to obtain the propagation characteristics of the shut-in water shock wave, the propagation characteristics of the shut-in water shock wave include the speed, pressure, direction change, wave propagation direction and fluid state in the wellbore in the four stages of water shock wave generation, water shock wave upward propagation, wave reflection at wellhead / well bottom, and wave attenuation or stabilization.

[0087] That is, according to the water shock wave propagation characteristics, ultra-high pressure simulation shut-in experiment can be carried out to observe and analyze the water shock pressure wave. As shown in Figure 4 After severe overflow and blowout occur, the wellhead blowout preventer should be closed immediately, and the water shock pressure wave generated by the ultra-high pressure emergency shut-in of the ultra-deep well has the same properties as acoustic waves, with typical elastic wave propagation, reflection and superposition of wave characteristics. The water shock wave process is divided into four stages: compression, recovery, re-compression, recovery, and final recovery, corresponding to the time period. The speed, pressure, direction change, wave propagation direction, and fluid state in the wellbore in the four stages of water shock wave generation, water shock wave upward propagation, wave reflection at wellhead / well bottom, and wave attenuation or stabilization are analyzed, and the physical characteristics of the water shock wave are summarized, That is, assuming that the wellhead flow rate before shut-in is , the pressure is , the water shock pressure wave speed generated by shut-in is , the well depth at the casing shoe is , according to the simulation experiment, the water shock pressure wave propagation process is divided into four stages, and the length of each stage is , and the water shock pressure wave propagation characteristics in each stage are studied and summarized.

[0088] The entire water shock pressure process takes into account the influence of sulfur precipitation, so the water shock pressure drop calculation brings in the sulfur precipitation wellbore pressure macroscopic calculation equation, and the water shock propagation process and its propagation characteristics are summarized in Table 1.

[0089] Table 1 Physical characteristics of shut-in water shock propagation process

[0090] By dividing the stages of water shock wave propagation, the speed and pressure change characteristics of water shock wave in different stages can be analyzed in detail, so as to more accurately describe the propagation characteristics of water shock wave. Based on the divided water shock wave propagation stages and the sulfur precipitation water shock wave speed equation, a physical model can be established to accurately describe the propagation characteristics of water shock wave.

[0091] S38: Establish a shut-in water hammer pressure calculation model based on the shut-in water hammer wave propagation characteristics, and obtain the hard shut-in water hammer pressure through the shut-in water hammer pressure calculation model and the wellbore parameters before hard shut-in, and the shut-in water hammer pressure calculation model is used to represent the corresponding relationship between the water hammer pressure and the wellbore parameters.

[0092] According to the wave propagation characteristics, the water hammer pressure dynamic value is indirectly obtained by combining the control equation of the water hammer pressure, that is, the shut-in time is not considered, and the relevant characteristic line equation set is obtained by the characteristic method. Figure 5 The grid diagram of the common characteristic line method in the embodiments of the present application is shown in FIG. 1. Then, the finite difference method is used to discretize the equation, and the flow rate and pressure drop boundary conditions at a certain time are brought in, and then the wellbore multiphase fluid pressure value after the water hammer phenomenon occurs at this time, that is, the hard shut-in water hammer pressure, is obtained.

[0093] Specifically, step S38 can include: Based on the law of conservation of mass and the law of conservation of momentum, the Bernoulli equation is combined to establish a shut-in water hammer pressure control equation; based on the ultra-deep well hard shut-in condition of sulfur extraction, the shut-in water hammer pressure control equation is analyzed and solved to obtain the wellbore multiphase fluid pressure value after the water hammer phenomenon occurs at different times; the wellbore multiphase fluid pressure value is taken as the shut-in water hammer pressure, and the change rule of the shut-in water hammer pressure under the multiphase flow condition and the influence degree of the casing size are analyzed.

[0094] The specific derivation process is as follows: A microelement is taken along the fluid flow direction of the wellbore annulus for research, based on the laws of conservation of mass and conservation of momentum, and the Bernoulli equation is combined to establish a shut-in water hammer pressure control equation as follows:

[0095] wherein, represents the transport velocity, represents the wellbore pressure, represents the wellbore density, represents the gravitational acceleration, represents the annular expansion cross-sectional radial deformation amount, represents the water hammer wave velocity, represents the coordinate in the well depth direction, t represents the time, represents the wellbore cross-sectional diameter size at the well depth of i represents the wellbore cross-sectional diameter size at the well depth of 0.

[0096] ​Based on the hard shut-in condition of ultra-deep well with sulfur precipitation and ultra-high pressure, the control equation is solved by analytical method, the shut-in time is not considered, the relevant characteristic line equation set is obtained by characteristic method, and the equation is discretized by finite difference method, the flow rate and pressure drop boundary conditions at a certain time are brought in, and then the wellbore multiphase fluid pressure value after water hammer phenomenon occurs at this time is calculated, that is, the shut-in water hammer pressure.

[0097] It should be noted that according to the overall idea of the analysis method of the shut-in water hammer pressure of the ultra-deep well with sulfur precipitation and ultra-high pressure, the specific influencing factor change process can be summarized, so the single factor is not analyzed here. Under the condition of sulfur precipitation, the annular gas phase proportion is the main reason affecting the transmission of water hammer pressure wave. Figure 6 The schematic diagram of the water hammer wave velocity changing with the sulfur gas phase proportion in the wellbore in the embodiments of the present application is shown in the figure. When the gas volume fraction is small, a small amount of gas can greatly reduce the water hammer wave velocity, but as the gas phase proportion increases, the influence on the water hammer wave velocity becomes smaller and smaller.

[0098] The simulation experiment results are verified to analyze the water hammer pressure change law and the influence degree of casing size under the condition of multiphase flow.

[0099] The experiment found that the casing size has little effect on the propagation speed of water hammer pressure, but overall, the water hammer wave velocity decreases with the increase of the casing inner diameter and increases with the increase of the casing wall thickness.

[0100] Analysis shows that: the wellbore water hammer pressure during shut-in is transmitted in the form of pressure wave, which presents the characteristics of periodic increase and decrease. With the extension of shut-in time, the pressure wave energy decays continuously, and the water hammer pressure fluctuation amplitude decreases continuously until it decreases to 0. The experimental results are consistent with the calculation results of shut-in water hammer pressure, which proves that the analysis method conforms to the actual situation.

[0101] By establishing the control equation of shut-in water hammer pressure, the pressure change law of multiphase fluid in the wellbore during shut-in can be reflected, and the wellbore multiphase fluid pressure value after water hammer phenomenon occurs at different times under the condition of ultra-deep well with sulfur precipitation and ultra-high pressure hard shut-in is obtained by analytical solution, which helps to predict the pressure change in the wellbore. At the same time, by analyzing the shut-in water hammer pressure change law under the condition of multiphase flow, the change of the pressure in the wellbore with time can be better understood, and the influence of the casing size on the water hammer pressure change can be analyzed, which can help to determine the appropriate casing size. That is, the water hammer pressure of the sulfur gas well during shut-in can be more accurately described and predicted, so as to improve the accuracy of calculation, reduce the risk of blowout and other accidents, and ensure the safety and efficiency of drilling operation.

[0102] In summary, the method for calculating the ultra-deep, high-pressure shut-in water hammer pressure of sulfur-containing gas wells provided in this application, by establishing a physical model of sulfur dissolution and precipitation in the wellbore, can accurately describe the transformation process of elemental sulfur between the formation and the wellbore, including dissolution, precipitation, and phase changes. This provides a foundation for subsequent wellbore pressure and water hammer pressure calculations. Calculating the critical suspension velocity helps determine the migration state of elemental sulfur within the wellbore, thereby predicting the flow characteristics of the fluid within the wellbore and further providing a basis for wellbore pressure calculations. The derived numerical expression for the wellbore pressure distribution of high-sulfur gas wells can consider the influence of elemental sulfur on wellbore pressure, improving the accuracy of the calculation and helping to more accurately predict the wellbore pressure distribution. By establishing an equation for the water hammer wave velocity of sulfur-containing precipitation under ultra-high pressure conditions, it can describe the ultra-high pressure... The propagation characteristics of water hammer waves during well shut-in of sulfur-containing gas wells under ultra-high pressure conditions provide important parameters for predicting water hammer pressure. By establishing a physical model of water hammer wave propagation during well shut-in, the propagation characteristics of water hammer waves, such as wave velocity, propagation direction, and pressure changes, are analyzed, providing a basis for predicting pressure changes within the wellbore. Finally, by establishing a calculation model for well shut-in water hammer pressure based on the propagation characteristics of water hammer waves, the model can predict the water hammer pressure variation under multiphase flow conditions, providing an important reference for the design and safety assessment of wellhead equipment. This improves the accuracy of water hammer pressure prediction during the well shut-in process of sulfur-containing gas wells, supports the design and safety assessment of wellhead equipment, and ensures the safety and efficiency of drilling operations. It also allows for a better understanding and control of wellbore pressure and water hammer pressure in sulfur-containing gas wells under ultra-high pressure conditions, reducing the risk of accidents such as well blowouts.

[0103] Based on the same inventive concept, this application also provides a device for calculating the shut-in water hammer pressure of ultra-deep wells containing sulfur precipitation.

[0104] Figure 7 This is a schematic diagram of the structure of the ultra-deep well high-pressure shut-in water hammer pressure calculation device containing sulfur precipitation, as described in the embodiments of this application. Figure One See Figure 7 As shown, the device may include: The precipitation calculation module 71 is used to determine the amount of elemental sulfur precipitated in the wellbore based on the physical model of sulfur dissolution and precipitation in the wellbore and the natural gas parameters in the wellbore. The physical model of sulfur dissolution and precipitation in the wellbore is established based on the physicochemical transformation characteristics of elemental sulfur entering the wellbore and is used to characterize the correspondence between the amount of elemental sulfur precipitated in the wellbore and the natural gas parameters in the wellbore. The flow velocity calculation module 72 is used to determine the critical flow velocity of elemental sulfur in the wellbore based on the critical flow velocity calculation model of elemental sulfur and the amount of elemental sulfur precipitation in the wellbore. The critical flow velocity calculation model of elemental sulfur is established based on the motion of elemental sulfur in a gas-liquid two-phase fluid using two-phase flow theory, and is used to characterize the correspondence between the critical flow velocity of elemental sulfur in the wellbore and the amount of elemental sulfur precipitation in the wellbore. The feature acquisition module 73 is configured to, when the annulus gas phase flow velocity is greater than the critical flow velocity of elemental sulfur in the wellbore, establish a shut-in water hammer wave propagation physical model based on a sulfur precipitation water hammer wave velocity equation and wellbore related parameters, and obtain shut-in water hammer wave propagation features through experiments based on the shut-in water hammer wave propagation physical model, wherein the sulfur precipitation water hammer wave velocity equation is derived based on a sulfur gas wellbore pressure distribution and a sulfur precipitation wellbore pressure macroscopic calculation equation. The pressure calculation module 74 is configured to establish a shut-in water hammer pressure calculation model based on the shut-in water hammer wave propagation features, and obtain a hard shut-in water hammer pressure based on the shut-in water hammer pressure calculation model and the wellbore parameters before hard shut-in, wherein the shut-in water hammer pressure calculation model is used to represent the corresponding relationship between the water hammer pressure and the wellbore parameters.

[0105] Further, as a refinement and extension of the device shown in Figure 7 , the embodiment of the present application also provides a device for calculating the shut-in water hammer pressure of a super-deep well with sulfur precipitation under ultra-high pressure.

[0106] Figure 8 The device for calculating the shut-in water hammer pressure of a super-deep well with sulfur precipitation under ultra-high pressure in the embodiment of the present application is shown in Figure Two , and as shown in Figure 8 , the device can include: The precipitation model generation module 81 is configured to obtain test parameters including at least a generation temperature, a generation pressure, and a solubility according to a separation and degradation reaction of a natural gas mixture containing a hydrogen sulfide component; determine a physical and chemical conversion path of elemental sulfur into a wellbore based on the test parameters; and establish a dissolution and precipitation physical model of sulfur in the wellbore based on the physical and chemical conversion path and a chemical reaction equilibrium and a physical dissolution equilibrium of elemental sulfur in a preset high-temperature and high-pressure environment, wherein the preset high-temperature and high-pressure environment is an environment with a temperature ≥ 150 ℃ and a pressure ≥ 69.8 MPa.

[0107] The physical and chemical conversion path includes: (1) a catalytic thermal degradation reaction of polysulfide hydrogen sulfide generated by elemental sulfur in the formation and the hydrogen sulfide component in the natural gas mixture with iron elements in the casing or iron elements in the formation within 4-6 hours in the preset high-temperature and high-pressure environment, so as to generate elemental sulfur; (2) in the well area of carbon dioxide injection drive, the hydrogen sulfide component in the natural gas mixture is also oxidized by carbon dioxide to generate elemental sulfur; (3) when the solubility of the elemental sulfur in the natural gas mixture is lower than the maximum solubility corresponding to the elemental sulfur, the elemental sulfur is converted from solid to liquid to enter the wellbore in the form of gas-liquid two-phase flow with the formation natural gas; when the solubility of the elemental sulfur in the natural gas mixture is higher than the maximum solubility, the elemental sulfur is no longer dissolved in the formation natural gas, and is brought into the wellbore in the form of liquid droplets or solid particles with the formation natural gas seepage.

[0108] wherein the chemical reaction equilibrium and the physical dissolution equilibrium of the elemental sulfur in the preset high temperature and high pressure environment include: a density calculation formula of the elemental sulfur and a flow state viscosity calculation formula of the elemental sulfur , wherein, denotes the density of the elemental sulfur in the conversion period, denote the density calculation parameters of the elemental sulfur respectively, denotes the conversion temperature, denotes the flow state viscosity of the elemental sulfur, denotes a constant term coefficient of the viscosity formula, denotes a first-order term coefficient of the viscosity with respect to temperature, denotes a second-order term coefficient of the viscosity with respect to temperature, denotes a third-order term coefficient of the viscosity with respect to temperature; wherein the dissolution and precipitation mathematical expressions of the sulfur in the wellbore include: , wherein, denotes the solubility of the elemental sulfur, denotes a dissolution coefficient, denotes a proportion of at least an acid gas component including hydrogen sulfide and carbon dioxide in the formation natural gas, denotes the density of the elemental sulfur in the conversion period, denotes the conversion temperature, denotes the dynamic precipitation amount of the elemental sulfur, denotes the density of the wellbore natural gas at the time when the elemental sulfur is not precipitated, denotes the density of the wellbore natural gas after the elemental sulfur has been precipitated for 15 minutes, denotes a constant term coefficient of the viscosity formula, denotes a first-order term coefficient of the viscosity with respect to temperature, denotes a second-order term coefficient of the viscosity with respect to temperature, denotes a third-order term coefficient of the viscosity with respect to temperature.

[0109] The precipitation calculation module 82 is configured to determine the precipitation amount of the elemental sulfur in the wellbore based on the dissolution and precipitation physical model of the sulfur in the wellbore and the wellbore natural gas parameters.

[0110] The flow rate model generation module 83 is configured to determine a motion equation of the elemental sulfur based on a migration mode of the physical quantity of the precipitated elemental sulfur according to the dissolution and precipitation physical model, and calculate a critical flow rate expression of the elemental sulfur according to a force condition corresponding to the migration mode, and calculate a critical flow rate of the elemental sulfur based on the critical flow rate expression.

[0111] wherein the motion equation includes: , The stress conditions include: Flow resistance of sulfur element The buoyancy and gravity of the sulfur element , The critical flow velocity of the sulfur element is expressed as: , Wherein, u most The critical flow velocity of the sulfur element is expressed as: The volume of precipitated sulfur element is expressed as: The density of the sulfur element during the conversion period is expressed as: The migration velocity of the sulfur element is expressed as: The migration time is expressed as: The air phase flow velocity in the well annulus is expressed as: The flow resistance of the sulfur element is expressed as: The buoyancy is expressed as: The gravity is expressed as: The gravitational acceleration is expressed as: The Stokes resistance coefficient is expressed as: The maximum cross-sectional area of the sulfur element is expressed as: The density of the wellbore gas after the sulfur element has been precipitated for 15 minutes is expressed as:

[0112] The flow velocity calculation module 84 is used to determine the critical flow velocity of the sulfur element in the wellbore based on the critical flow velocity calculation model of the sulfur element and the amount of sulfur element precipitated in the wellbore.

[0113] The pressure distribution generation module 85 is used to, when the flow state of the gas and the sulfur element in the wellbore and the production conditions of the gas well meet the premise conditions, introduce calculation auxiliary parameters related to sulfur element based on the change of the gas-liquid multiphase flow of the wellbore with sulfur precipitation, follow the law of conservation of energy, establish a macroscopic calculation equation of wellbore pressure, wherein the premise conditions include that the production process of the gas well is stable production with constant yield, the flow of gas and sulfur element in the wellbore is one-dimensional flow, all characteristic parameters of gas and sulfur element at any interface of the wellbore are the same, and gas and the outside do not do work on each other, and the calculation auxiliary parameters include accelerated pressure drop of precipitated sulfur, friction pressure drop, lifting pressure drop, and along-the-way energy loss coefficient; the solubility of the sulfur element and the change of the volume proportion of the sulfur element in the wellbore caused by the flow rate difference between different phases are introduced into the macroscopic calculation equation of wellbore pressure, and a numerical calculation expression of the pressure distribution of the wellbore of the high-sulfur gas well is established.

[0114] The macroscopic calculation equation of wellbore pressure is: , The accelerated pressure drop is: , The friction pressure drop is: , Increase the voltage drop as follows: , in, This represents the wellbore pressure at any given time. This represents the initial wellbore pressure. Indicates pressure drop. These represent the pressure drops in the liquid phase, gas phase, and sulfur precipitation phase of the wellbore, respectively. These represent the accelerated pressure drops in the liquid phase, gas phase, and sulfur precipitation phase of the wellbore, respectively. These represent the frictional pressure drops in the liquid phase, gas phase, and sulfur precipitation phase of the wellbore, respectively. These represent the pressure drop during the rise of the liquid phase, gas phase, and sulfur precipitation phase in the wellbore, respectively. These represent the viscosities of the liquid phase, gas phase, and precipitated sulfur in the wellbore, respectively. These represent the densities of the liquid phase, gas phase, and precipitated sulfur in the wellbore, respectively. These represent the migration velocities of the liquid phase, gas phase, and precipitated sulfur in the wellbore after considering the slippage effect. These represent the energy loss coefficients along the wellbore for the liquid phase, gas phase, and sulfur precipitation, respectively. Indicates the length of the wellbore. Indicates the wellbore volume. Indicates the diameter of the wellbore cross-section. Represents gravitational acceleration; The wave velocity equation generation module 86 simplifies the multiphase flow motion within the wellbore to flow along the wellbore axis, and analyzes the compression deformation of the sulfur-containing gas, liquid, and solid phases under ultra-high pressure conditions, as well as the expansion deformation of the wellbore annulus under ultra-high pressure conditions, obtaining the compression deformation of each phase and the expansion deformation of the annulus. The compression deformation of each phase and the expansion deformation of the annulus are added together to obtain the change in wellbore volume. The elastic modulus and volume fraction of the sulfur-containing gas, liquid, and solid phases are obtained. Based on the drilling fluid returned before shut-in, the apparent density of the multiphase fluid in the wellbore during overflow shut-in water hammer is calculated. Ignoring multiphase fluid loss, based on the laws of fluid mass conservation and momentum conservation, the elastic modulus and volume fraction of the sulfur-containing gas, liquid, and solid phases, the apparent density of the multiphase fluid in the wellbore during overflow shut-in water hammer, and the change in wellbore volume are introduced into the numerical calculation expression for the pressure distribution in the wellbore of high-sulfur gas wells to establish the water hammer wave velocity equation.

[0115] The compression deformation of each phase includes: the compression deformation of the sulfur-containing gas phase, the compression deformation of the liquid phase, and the compression deformation of the solid phase. The amount of sulfur-containing gas phase compression deformation involved is: , The amount of liquid phase compression deformation involved is: , The solid-phase compression deformation amount involved is: , The annulus expansion deformation amount is: , The sum of the proportions of the gas-liquid-solid three phases in the wellbore is 100%, and the wave velocity equation is: , wherein, represents the water hammer wave velocity, represents the sulfur-containing gas-phase compression deformation amount, represents the pressure drop, represents the liquid-phase compression deformation amount, represents the solid-phase compression deformation amount, represents the annulus expansion deformation amount, represents the annulus cross-sectional area, represents the sulfur-containing gas-phase component in the wellbore annulus, represents the sulfur-containing gas-phase elastic modulus in the wellbore annulus, represents the liquid-phase component in the wellbore annulus, represents the liquid-phase elastic modulus in the wellbore annulus, represents the solid-phase component in the wellbore annulus, represents the solid-phase elastic modulus in the wellbore annulus, represents the wellbore elastic modulus, represents the wellbore height at which annulus expansion occurs, represents the time difference, represents the wellbore cross-sectional diameter, represents the annulus expansion cross-sectional radial deformation amount, represents the apparent density of the multiphase fluid in the wellbore at the time of overflow shut-in water hammer.

[0116] The feature acquisition module 87 is configured to, when the annulus gas flow rate is greater than the critical flow rate of elemental sulfur in the wellbore, integrate a dynamic influence variable of elemental sulfur on the water hammer wave velocity into a water hammer wave velocity equation of sulfur precipitation based on the water hammer wave velocity equation, and establish a water hammer wave propagation model by using fluid mechanics theory and combining the dynamics of the sulfur-containing phase, the liquid phase, the solid phase, and the annulus. The dynamic influence variable includes wellbore size, fluid properties, pressure distribution, and elemental sulfur content. The propagation process of the shut-in water hammer wave in the wellbore is simulated based on the shut-in water hammer wave propagation physical model using simulation software to obtain the shut-in water hammer wave propagation characteristics, including the velocity, pressure, direction change, wave propagation direction, and fluid state in the wellbore at four stages of water hammer wave generation, upward propagation, wave reflection at the wellhead / well bottom, and wave attenuation or stabilization.

[0117] The pressure calculation module 88 is configured to establish a shut-in water hammer pressure control equation based on the law of conservation of mass and the law of conservation of momentum in combination with the Bernoulli equation, and to obtain wellbore multiphase fluid pressure values after water hammer occurs at different times by solving the shut-in water hammer pressure control equation based on the super-high pressure hard shut-in condition of the ultra-deep well with sulfur extraction. The shut-in water hammer pressure control equation is as follows: ; Wherein, represents a migration velocity, represents a wellbore pressure, represents a wellbore density, represents a gravitational acceleration, represents a radial deformation amount of an annular expansion cross section, represents a water hammer wave speed, represents a coordinate in a well depth direction, t represents a time, represents a wellbore cross section diameter at a well depth of i represents a wellbore cross section diameter at a well depth of represents a wellbore cross section diameter at a well depth of

[0118] It should be noted that the above device embodiments are similar to the above method embodiments in terms of description, and have similar beneficial effects to the method embodiments. For technical details not disclosed in the device embodiments of the present application, please refer to the description of the method embodiments of the present application.

[0119] Based on the same inventive concept, the embodiments of the present application further provide a computer device.

[0120] Figure 9 FIG. 1 shows a structural schematic diagram of a computer device according to an embodiment of the present application. Figure 9 The computer device can include a memory 91, a processor 92, and a computer program stored in the memory 91. The processor 92 executes the computer program to implement the method in the above embodiments.

[0121] It should be noted that the above computer device embodiments are similar to the above method embodiments in terms of description, and have similar beneficial effects to the method embodiments. For technical details not disclosed in the computer device embodiments of the present application, please refer to the description of the method embodiments of the present application.

[0122] Based on the same inventive concept, the embodiments of the present application further provide a computer readable storage medium. The computer readable storage medium stores a computer program. When the computer program is executed by a processor, the method in the above embodiments is implemented.

[0123] It should be noted that the above description of the computer-readable storage medium embodiments is similar to the description of the above method embodiments, and has similar beneficial effects as the method embodiments. For technical details of the computer-readable storage medium embodiments of the present application that are not disclosed, please refer to the description of the method embodiments of the present application for understanding.

[0124] Based on the same inventive concept, the embodiments of the present application further provide a computer program product. The computer program product comprises a computer program which, when executed by a processor, implements the method in the foregoing embodiments.

[0125] It should be noted that the above description of the computer program product embodiments is similar to the description of the above method embodiments, and has similar beneficial effects as the method embodiments. For technical details of the computer program product embodiments of the present application that are not disclosed, please refer to the description of the method embodiments of the present application for understanding.

[0126] The above description is merely specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for calculating the shut-in water hammer pressure in ultra-deep wells containing sulfur precipitation, characterized in that, The method includes: The amount of elemental sulfur released from the wellbore is determined based on a physical model of sulfur dissolution and precipitation in the wellbore and natural gas parameters. The physical model of sulfur dissolution and precipitation in the wellbore is established based on the physicochemical transformation characteristics of elemental sulfur entering the wellbore and is used to characterize the correspondence between the amount of elemental sulfur released from the wellbore and the natural gas parameters in the wellbore. The critical flow rate of elemental sulfur in the wellbore is determined based on the critical flow rate calculation model of elemental sulfur and the amount of elemental sulfur precipitated in the wellbore. The critical flow rate calculation model of elemental sulfur is established based on the two-phase flow theory based on the motion of elemental sulfur in a gas-liquid two-phase fluid, and is used to characterize the correspondence between the critical flow rate of elemental sulfur in the wellbore and the amount of elemental sulfur precipitated in the wellbore. When the air phase velocity in the well ring is greater than the critical velocity of elemental sulfur in the wellbore, a physical model for the propagation of shut-in water hammer waves is established based on the equation for the sulfur-containing precipitated water hammer wave velocity and relevant wellbore parameters. Experiments are then conducted using the physical model to obtain the propagation characteristics of shut-in water hammer waves. The equation for the sulfur-containing precipitated water hammer wave velocity is derived from the macroscopic calculation equations of the pressure distribution in the wellbore of sulfur-containing gas wells and the pressure in the wellbore of sulfur precipitation. A well shut-in water hammer pressure calculation model is established based on the propagation characteristics of water hammer waves. The water hammer pressure of the hard shut-in well is obtained through the well shut-in water hammer pressure calculation model and the wellbore parameters before hard shut-in. The well shut-in water hammer pressure calculation model is used to characterize the correspondence between water hammer pressure and wellbore parameters.

2. The method according to claim 1, characterized in that, Before determining the amount of elemental sulfur precipitated in the wellbore based on a physical model of sulfur dissolution and precipitation in the wellbore and wellbore natural gas parameters, the method further includes: Based on the separation and degradation reaction of natural gas mixtures containing hydrogen sulfide components, experimental parameters including at least the generation temperature, generation pressure, and solubility are obtained; The physicochemical transformation pathways of elemental sulfur entering the wellbore were determined based on the experimental parameters. Based on the aforementioned physicochemical transformation pathway and the chemical reaction equilibrium and physical dissolution equilibrium of elemental sulfur in a preset high-temperature and high-pressure environment, a physical model for the dissolution and precipitation of sulfur in the wellbore is established. The preset high-temperature and high-pressure environment is an environment with a temperature ≥150 ℃ and a pressure ≥69.8 MPa.

3. The method according to claim 2, characterized in that, The physicochemical transformation pathways include one or more of the following pathways: The polysulfides generated from the mixture of elemental sulfur in the formation and hydrogen sulfide in the natural gas undergo a catalytic thermal degradation reaction with iron elements in the casing or the formation within 4–6 hours in the preset high temperature and high pressure environment, thereby generating elemental sulfur. In well areas where carbon dioxide is injected, the hydrogen sulfide component in the natural gas mixture is oxidized by carbon dioxide to produce elemental sulfur. When the solubility of elemental sulfur in the natural gas mixture is lower than the maximum solubility of elemental sulfur, elemental sulfur undergoes solid-liquid transformation and enters the wellbore in the form of a gas-liquid two-phase flow along with the formation natural gas. When the solubility of elemental sulfur in the natural gas mixture is higher than the maximum solubility, elemental sulfur no longer dissolves in the formation natural gas and is carried into the wellbore in the form of droplets or solid particles with the formation natural gas seepage. in, The chemical reaction equilibrium and physical dissolution equilibrium of elemental sulfur in a pre-set high-temperature and high-pressure environment include: the formula for calculating the density of elemental sulfur. Formula for calculating the fluid viscosity of elemental sulfur , in, This indicates the density during the conversion of elemental sulfur. These represent the parameters for calculating the density of elemental sulfur. Indicates the conversion temperature. This indicates the viscosity of elemental sulfur in its fluid state. This represents the coefficient of the constant term in the viscosity formula. This represents the coefficient of viscosity with respect to the first-order term of temperature. This represents the coefficient of the quadratic term of viscosity with respect to temperature. This represents the coefficient of viscosity with respect to the cubic term of temperature; The mathematical expressions for the dissolution and precipitation of sulfur in wellbores include: ， in, Indicates the solubility of elemental sulfur. Indicates the solubility coefficient. This indicates the percentage of acidic gas components in the formation natural gas, including at least hydrogen sulfide and carbon dioxide. This indicates the density during the conversion of elemental sulfur. Indicates the conversion temperature. This indicates the amount of elemental sulfur dynamically released. This represents the density of natural gas in the wellbore at the moment before elemental sulfur precipitates. This indicates the density of the natural gas in the wellbore 15 minutes after elemental sulfur has been released. This represents the coefficient of the constant term in the viscosity formula. This represents the coefficient of viscosity with respect to the first-order term of temperature. This represents the coefficient of the quadratic term of viscosity with respect to temperature. This represents the coefficient of viscosity with respect to the cubic term of temperature.

4. The method according to claim 1, characterized in that, Before determining the critical flow rate of elemental sulfur in the wellbore based on the critical flow rate calculation model of elemental sulfur and the amount of elemental sulfur precipitation in the wellbore, the method further includes: Based on the physical model of dissolution and precipitation, the motion equation of sulfur is determined by the transport mechanism of the physical quantities of sulfur. Based on the equation of motion and the force conditions corresponding to the transport mode, the critical velocity calculation expression for elemental sulfur is derived, and a critical velocity calculation model is constructed based on the equation of motion for elemental sulfur and the critical velocity calculation expression.

5. The method according to claim 4, characterized in that, The equations of motion include: ， The stress conditions include: Flow resistance of elemental sulfur Buoyancy of elemental sulfur ,gravity , The critical flow rate expression for the sulfur element is: ， in, u most This indicates the critical flow rate of elemental sulfur. This represents the volume of elemental sulfur that has precipitated. This indicates the density during the conversion of elemental sulfur. Indicates the transport rate of elemental sulfur. Indicates the migration time. This indicates the air phase velocity in the well ring. This indicates the flow resistance of elemental sulfur. Indicates buoyancy. Represents gravity. Represents gravitational acceleration. This represents the Stokes drag coefficient. This represents the maximum cross-sectional area of ​​elemental sulfur. This indicates the density of natural gas in the wellbore 15 minutes after elemental sulfur has been released.

6. The method according to claim 1, characterized in that, Before establishing a physical model for shut-in water hammer wave propagation based on the sulfur-containing precipitation water hammer wave velocity equation and relevant wellbore parameters, the method further includes: When the flow state of gas and elemental sulfur in the wellbore and the gas well production conditions meet the preconditions, based on the change of gas-liquid multiphase flow energy in the wellbore containing sulfur precipitation, auxiliary calculation parameters involving sulfur elements are introduced, and the law of conservation of energy is followed to establish a macroscopic calculation equation for wellbore pressure. The preconditions include that the gas well production process is a stable production with constant output, the flow of gas and elemental sulfur in the wellbore is one-dimensional, all characteristic parameters of gas and elemental sulfur are the same at any interface in the wellbore, and there is no mutual work between the gas and the outside world. The auxiliary calculation parameters include the acceleration pressure drop of sulfur precipitation, friction pressure drop, lift pressure drop, and friction loss coefficient. The solubility of elemental sulfur and the change in the volume ratio of elemental sulfur in the wellbore caused by the flow velocity difference between different phases are introduced into the macroscopic calculation equation of wellbore pressure to establish a numerical calculation expression for the wellbore pressure distribution of high sulfur-containing gas wells. The multiphase flow motion in the wellbore is simplified to flow along the wellbore axis. The compression deformation of the sulfur-containing gas phase, liquid phase and solid phase above 69.8 MPa and the expansion deformation of the wellbore annulus above 69.8 MPa are analyzed to obtain the compression deformation of each phase and the expansion deformation of the annulus. The change in wellbore volume is obtained by adding the compression deformation of each phase and the annular expansion deformation. Obtain the elastic modulus and volume fraction of sulfur-containing gaseous, liquid, and solid phases; Based on the measurement of the drilling fluid discharged before shutting in the well, calculate the apparent density of the multiphase fluid in the wellbore during the overflow shut-in water hammer. Ignoring the loss of multiphase fluids, based on the laws of conservation of fluid mass and momentum, the elastic modulus and volume fraction of sulfur-containing gas, liquid and solid phases, the apparent density of multiphase fluids in the wellbore during overflow shut-in water hammer, and the change in wellbore volume are introduced into the numerical calculation expression of the pressure distribution in the wellbore of the high sulfur-containing gas well to establish the water hammer wave velocity equation.

7. The method according to claim 6, characterized in that, The macroscopic calculation equation for wellbore pressure is as follows: ， The accelerated pressure drop is: ， The frictional pressure drop is: ， The increased pressure drop is: ， in, This represents the wellbore pressure at any given time. This represents the initial wellbore pressure. Indicates pressure drop. These represent the pressure drops in the liquid phase, gas phase, and sulfur precipitation phase of the wellbore, respectively. These represent the accelerated pressure drops in the liquid phase, gas phase, and sulfur precipitation phase of the wellbore, respectively. These represent the frictional pressure drops in the liquid phase, gas phase, and sulfur precipitation phase of the wellbore, respectively. These represent the pressure drop during the rise of the liquid phase, gas phase, and sulfur precipitation phase in the wellbore, respectively. These represent the viscosities of the liquid phase, gas phase, and precipitated sulfur in the wellbore, respectively. These represent the densities of the liquid phase, gas phase, and precipitated sulfur in the wellbore, respectively. These represent the migration velocities of the liquid phase, gas phase, and precipitated sulfur in the wellbore after considering the slippage effect. These represent the energy loss coefficients along the wellbore for the liquid phase, gas phase, and sulfur precipitation, respectively. Indicates the length of the wellbore. Indicates the wellbore volume. Indicates the diameter of the wellbore cross-section. Represents gravitational acceleration; The compression deformation of each phase includes: the compression deformation of the sulfur-containing gas phase, the compression deformation of the liquid phase, and the compression deformation of the solid phase. The amount of sulfur-containing gas phase compression deformation involved is: ， The amount of liquid phase compression deformation involved is: ， The solid-phase compressive deformation involved is: ， The annular expansion deformation is: ， The sum of the proportions of the gas, liquid, and solid phases in the wellbore is 100%, and the water hammer wave velocity equation is: ， in, Indicates the water hammer wave speed, This indicates the amount of compression deformation of the sulfur-containing gas phase. Indicates pressure drop. This indicates the amount of compression deformation in the liquid phase. This represents the amount of solid-phase compression deformation. This indicates the amount of deformation caused by the controlled expansion. Represents the cross-sectional area of ​​the annulus. This indicates the sulfur-containing gas phase composition of the wellbore annulus. This represents the elastic modulus of the sulfur-containing gas phase in the wellbore annulus. Indicates the liquid phase composition of the wellbore annulus. This indicates the elastic modulus of the liquid phase in the wellbore annulus. Indicates the solid phase composition of the wellbore annulus. This represents the elastic modulus of the solid phase in the wellbore annulus. This represents the elastic modulus of the well wall. This indicates the height of the wellbore where annular expansion occurs. Indicates time difference, Indicates the diameter of the wellbore cross-section. This represents the radial deformation of the annular expansion cross section. This represents the apparent density of the multiphase fluid in the wellbore during overflow shut-off water hammer.

8. The method according to claim 1, characterized in that, The physical model of shut-in water hammer wave propagation is established based on the equation of sulfur-containing precipitation water hammer wave velocity and relevant wellbore parameters. Experiments are then conducted using this physical model to obtain the propagation characteristics of shut-in water hammer waves, including: Based on the equation for the water hammer velocity of sulfur-containing precipitation water, the dynamic influence variables of elemental sulfur on the water hammer velocity are integrated into the equation for the water hammer velocity of sulfur-containing precipitation water in the influent. Using fluid mechanics theory, combined with the dynamics of sulfur-containing phase, liquid phase, solid phase and annular space, a propagation model of water hammer wave is established. The dynamic influence variables include wellbore size, fluid properties, pressure distribution and elemental sulfur content. Based on the physical model of water shock wave propagation in a shut-in well, simulation software is used to simulate the propagation process of water shock wave in the wellbore and obtain the propagation characteristics of water shock wave in a shut-in well. The propagation characteristics of water shock wave in a shut-in well include the velocity, pressure, direction changes, and wave propagation direction in four stages: water shock wave generation, upward propagation of water shock wave, reflection of wave at the wellhead / bottom of the well, and wave attenuation or stabilization, as well as the fluid state in the wellbore.

9. The method according to claim 1, characterized in that, A well shut-in water hammer pressure calculation model is established based on the propagation characteristics of water hammer waves. The water hammer pressure in the hard shut-in well is obtained through this model and the wellbore parameters before hard shut-in. The well shut-in water hammer pressure calculation model is used to characterize the correspondence between water hammer pressure and wellbore parameters, including: Based on the laws of conservation of fluid mass and momentum, and combined with Bernoulli's equation, the control equation for shut-in water hammer pressure is established. Based on the ultra-high pressure hard shut-in condition of ultra-deep wells containing sulfur precipitation, the control equation of shut-in water hammer pressure is analytically solved to obtain the multiphase fluid pressure values ​​of the wellbore after water hammer occurs at different times. The pressure value of the multiphase fluid in the wellbore is used as the water hammer pressure for hard shut-off wells. The control equation for the shut-in water hammer pressure is as follows: ， in, Indicates the speed of movement. Indicates wellbore pressure, represents the wellbore density, Represents gravitational acceleration. This represents the radial deformation of the annular expansion cross section. Indicates the water hammer wave speed, Coordinates representing the well depth direction. t Indicates time, Indicates well depth as i The diameter of the well shaft cross-section at that location. This indicates the diameter of the wellbore cross-section at a depth of 0.

10. A device for calculating the water hammer pressure of ultra-deep wells containing sulfur precipitation under ultra-high pressure shut-in conditions, characterized in that, The device includes: The precipitation calculation module is used to determine the amount of elemental sulfur precipitated in the wellbore based on the physical model of sulfur dissolution and precipitation in the wellbore and the natural gas parameters in the wellbore. The physical model of sulfur dissolution and precipitation in the wellbore is established based on the physicochemical transformation characteristics of elemental sulfur entering the wellbore and is used to characterize the correspondence between the amount of elemental sulfur precipitated in the wellbore and the natural gas parameters in the wellbore. The flow velocity calculation module is used to determine the critical flow velocity of elemental sulfur in the wellbore based on the critical flow velocity calculation model of elemental sulfur and the amount of elemental sulfur precipitated in the wellbore. The critical flow velocity calculation model of elemental sulfur is established based on the motion of elemental sulfur in a gas-liquid two-phase fluid using two-phase flow theory, and is used to characterize the correspondence between the critical flow velocity of elemental sulfur in the wellbore and the amount of elemental sulfur precipitated in the wellbore. The feature acquisition module is used to establish a physical model of shut-in water hammer wave propagation based on the sulfur-containing precipitation water hammer wave velocity equation and relevant well parameters when the air phase flow velocity in the well ring is greater than the critical flow velocity of elemental sulfur in the well. The module then conducts experiments using the shut-in water hammer wave propagation physical model to obtain the propagation characteristics of the shut-in water hammer wave. The sulfur-containing precipitation water hammer wave velocity equation is derived from the macroscopic calculation equation of the pressure distribution in the wellbore of sulfur-containing gas well and the pressure in the wellbore of sulfur precipitation. The pressure calculation module is used to establish a shut-in water hammer pressure calculation model based on the propagation characteristics of shut-in water hammer waves, and to obtain the hard shut-in water hammer pressure through the shut-in water hammer pressure calculation model and the wellbore parameters before hard shut-in. The shut-in water hammer pressure calculation model is used to characterize the correspondence between water hammer pressure and wellbore parameters.

11. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 9.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 9.

13. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 9.

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