System for evaluating throttling and installation depth of underground throttling valve

Abstract

The invention discloses an evaluation system for throttling and mounting depth of an underground throttle valve, belongs to evaluation of mounting depth of a throttle valve, and aims to evaluate mounting depth of a multistage throttle valve in the process of mounting the throttle valve. Comprising a user interface layer used for setting environment parameters and throttle valve parameters; the logic calculation layer is used for providing logic program support, iteratively calculating wellbore pressure and temperature and completing installation depth evaluation of the throttle valve; the data layer is used for storing data and providing data support for the logic layer; during evaluation, the user interface layer transmits input parameters to the logic calculation layer, the logic calculation layer performs calculation according to data transmitted by the user interface layer or / and calls data stored in the data layer, the logic calculation layer stores a calculation result in the data layer, and the user interface layer displays related data. By means of the evaluation system, the pressure and temperature of the gas well, the installation depth of the multi-stage throttling valve and the pressure and temperature before and after throttling can be evaluated.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, and relates to the evaluation of the installation depth of throttle valves during offshore oil and gas extraction, and particularly to an evaluation system for the throttling and installation depth of downhole throttle valves. Background Technology

[0002] With the increasing depth of offshore oil and gas extraction in recent years, the pressure and temperature during oil and gas production have also increased. Traditional wellhead throttling methods are prone to producing hydrates due to sudden changes in temperature and pressure, causing blockage of gas production pipelines and damage to surface equipment. Furthermore, surface throttling is prone to leakage of high-temperature and high-pressure oil and gas, which affects production and threatens the safety of surface workers, posing significant safety hazards.

[0003] Downhole choke valves enable throttling, pressure reduction, and cooling processes to occur within the well, minimizing wellhead blockage and oil / gas leakage. However, due to current offshore downhole oil and gas extraction depths exceeding several thousand meters, designers and operators find it difficult to rely on experience to place choke valves of appropriate nozzle diameters at suitable locations in deep wells. Improper selection of choke valve installation depth and nozzle diameter can easily lead to hydrate blockage of the choke valve, resulting in valve damage and production shutdown. When a single-stage choke valve is insufficient to meet throttling and pressure reduction requirements, the combined use of multiple choke valves further complicates selection and layout. Therefore, there is an urgent need for a tool that can guide the selection of choke valve nozzle diameters and depth layout under specific operating conditions, assisting designers and operators in selecting and installing choke valves, improving work efficiency, and ensuring safety.

[0004] The installation depth of a downhole throttle valve determines the environmental pressure and temperature it will face during operation. Inappropriate installation depth and throttle nozzle selection will affect the valve's service life, impacting oil and gas production and potentially causing safety accidents. Therefore, it is necessary to provide a method for evaluating the installation depth of multi-stage throttle valves during the installation process. Summary of the Invention

[0005] The purpose of this invention is to provide a downhole throttling valve throttling and installation depth evaluation system so as to evaluate the installation depth of multi-stage throttling valves during the installation process.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution: A system for evaluating the throttling and installation depth of a downhole throttle valve, comprising: The user interface layer is used to set environmental parameters and throttle valve parameters; The logic calculation layer provides logic program support, iteratively calculates wellbore pressure and temperature, and completes the evaluation of the throttle valve installation depth; The data layer is used to store data and provide data support for the logic layer. During evaluation, the user interface layer passes the input parameters to the logic calculation layer. The logic calculation layer performs calculations based on the data passed from the user interface layer and / or by calling the data stored in the data layer. The logic calculation layer stores the calculation results in the data layer. The user interface layer displays the data output by the logic calculation layer and stored in the data layer in graphical or textual form.

[0007] Furthermore, the specific steps for system evaluation are as follows: Step 1: Set the gas well depth, working cylinder diameter, initial pressure, and initial temperature through the user interface layer; Step 2: Set CO2 content and production parameters through the user interface layer; Step 3: Set the installation depth and throttle nozzle diameter of throttle valve one and throttle valve two through the user interface layer; Step 4: Submit the data set in steps 1-3; Step 5: Determine whether the flow rate of throttle valve one has reached the critical flow of throttle valve one; if it has, proceed to step 6; if it has not, proceed to step 8. Step 6: Determine whether the preset target pressure has reached the critical flow of the throttle valve; if it is greater than the critical flow, proceed to step 2 and re-enter the production allocation; if it is not greater than the critical flow, proceed to step 7. Step 7, input and submit target pressure one as a candidate; Step 8: Determine if the depth of the second throttle valve is 0; if it is not 0, proceed to step 9; if it is 0, proceed to step 12. Step 9: Determine whether the flow rate of throttle valve 2 has reached the critical flow of throttle valve 2; if it has, proceed to step 10; if it has not, proceed to step 12. Step 10: Determine whether the preset target pressure 2 has reached the critical flow of the throttle valve 2; if it is greater than the critical flow, proceed to step 2 and re-enter the production allocation; if it is not greater than the critical flow, proceed to step 11. Step 11, input and submit target pressure two as a candidate; Step 12, output the result.

[0008] Furthermore, in steps 5 and 9, when determining whether the flow rate of the corresponding throttle valve reaches the critical flow of the corresponding throttle valve, the determination method is as follows: like When this happens, the critical flow is reached; like If so, the critical flow has not been reached; in, Indicates the upstream pressure of the throttle nozzle. Indicates the downstream pressure of the throttle nozzle; This represents the gas adiabatic index, with a value of 1.3.

[0009] Furthermore, in steps 6 and 10, when determining whether the corresponding target pressure has reached the critical flow of the corresponding throttle valve, the determination method is as follows: like If the target pressure is within a critical flow range, then the target pressure is in a critical flow range; otherwise, the target pressure is in a non-critical flow range.

[0010] Furthermore, the specific steps taken by the logic computation layer during logic computation are as follows: Step S1: Input initial parameters; Input initial parameters, including initial pressure at the bottom of the wellbore, initial temperature at the bottom of the wellbore, desired production rate, well depth, installation depth of choke valve one, installation depth of choke valve two, diameter of choke valve one nozzle, diameter of choke valve two nozzle, wellbore diameter, and CO2 content (the value of the compressibility coefficient Z is related to this CO2 content). Step S2: Calculate the pressure gradient and loss before the throttle valve 1. Calculate the outlet pressure of the infinitesimal segment based on its length. And the value of pressure loss;

[0011] ; in, Indicates the initial pressure. Indicates loss due to gravity. Indicates friction loss. Indicates kinetic energy loss; Step S3: Compare the loss deviation of the throttle valve; The loss value obtained in step S2 The loss value is compared with a preset deviation value; if the loss value is less than or equal to the deviation value, proceed to step S5 and record the current outlet pressure. Otherwise, proceed to step S4; Step S4: Iteratively correct the loss value of the throttle valve; The loss value obtained in step S2 Replace the preset deviation value and re-enter step S3 for iteration until the condition is met and proceed to step S5; Step S5: Calculate the inlet temperature of throttle valve one; Calculate the inlet temperature of throttle valve one based on the initial temperature of the current micro-element segment. The calculation formula is: ; ; in, This indicates the initial temperature at the bottom of the wellbore. This indicates the starting depth value of the selected micro-element. This represents the endpoint depth value of the selected micro-element segment. This represents the unit change in oil and gas temperature. This represents the length of a unit tubular element within a micro-element segment. represents the wellbore diameter, Indicates the overall heat transfer coefficient. Indicates the thermal conductivity of the formation. Represents a dimensionless time function. Indicates the number of days. Indicates fluid temperature. This indicates the original temperature of the formation. This represents the Joule-Thomson coefficient. Indicates the pressure gradient. Indicates the coefficient of friction. Indicates the oil and gas flow rate. This indicates the specific heat capacity at constant pressure. Step S6, Depth determination of throttle valve; Determine whether the currently calculated depth of the micro-element segment reaches the preset installation depth of the throttle valve; if not, proceed to step S2; if so, proceed to step S7. Step S7: Calculate the pressure and temperature reduction of the throttle valve. Calculate the pressure after throttling. Temperature after throttling The specific calculation formula is as follows: ; ; in, Indicates the adiabatic index of oil and gas. Indicates the relative density of oil and gas. This represents the gas compressibility coefficient at the pressure before throttling; This indicates a desired output; Indicates the diameter of the throttle nozzle; Step S8: Calculate the pressure gradient and loss before the valve of throttle valve 2; Using the temperature and pressure after throttling by throttling valve one as the initial parameters for throttling valve two, calculate the pressure gradient and loss before throttling valve two; the calculation formula is: ; in, Indicates loss due to gravity. Indicates friction loss. Indicates kinetic energy loss; Step S9: Compare the two loss deviations of the throttle valve; The loss value obtained in step S8 The loss value is compared with a preset deviation value; if the loss value is less than or equal to the deviation value, proceed to step S11 and record the current outlet pressure. Otherwise, proceed to step S10; Step S10: Iteratively correct the loss value of the second throttle valve; The loss value obtained in step S8 Replace the preset deviation value and re-enter step S9 for iteration until the condition is met and proceed to step S11; Step S11: Calculate the inlet temperature of throttle valve two; The formula for calculating the inlet temperature of valve 2 is the same as that in step S5; Step S12: Determine the number of throttle valves; Determine if the number of throttle valves is 1; if yes, proceed to step S15; otherwise, proceed to step S13. Step S13, Depth determination of throttle valve II; Determine whether the currently calculated depth of the micro-element segment has reached the preset installation depth of the second throttle valve; if not, proceed to step S8; if so, proceed to step S14. Step S14: Calculate the pressure and temperature drop of the second throttle valve; The calculation formula for the pressure and temperature drop of the second throttle valve is the same as that in step S7. Step S15, output the result; Repeat steps S2-S5 and S8-S11 until the entire well section has been traversed; finally, output the evaluation results. The evaluation results include the pressure distribution curve of the entire wellbore, the temperature distribution curve of the entire wellbore, the pressure and temperature before and after throttling of each throttling valve, the determination of whether the throttling nozzle has reached the critical flow, and the recommended throttling nozzle diameter and installation depth.

[0012] The beneficial effects of this invention are as follows: 1. In this invention, the evaluation system can assess the pressure and temperature of gas wells, the installation depth of multi-stage throttle valves, and the pressure and temperature before and after throttling. The selection of throttle nozzle diameter is more accurate, the installation depth of throttle valves is more precise and appropriate, oil and gas production is smoother, and production safety accidents are effectively avoided.

[0013] 2. In this invention, the system helps to solve the problem that gas well pressure, temperature and throttling pressure reduction and cooling models are difficult to guide users to complete the selection of throttling valve and the determination of installation depth. It helps users to intuitively operate according to the process and complete the setting of throttling valve nozzle diameter and installation depth.

[0014] 3. In this invention, the system integrates the wellbore temperature and pressure model as well as the throttling cooling and pressure reduction model, so that the evaluation of multiple models can be completed in one operation, which is fast and efficient. Attached Figure Description

[0015] Figure 1 This is a system architecture diagram of the present invention; Figure 2 This is a schematic diagram of the evaluation process of the present invention; Figure 3 This is a schematic diagram of the logic calculation process of the logic calculation layer of the present invention; Figure 4 This is a partial screenshot of the login page of this invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0017] Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] Example 1 This embodiment provides an evaluation system for downhole choke valve throttling and installation depth, used to evaluate the pressure and temperature of a gas well, the installation depth of a multi-stage choke valve, and the pressure and temperature before and after throttling. This evaluation system is implemented using computer software and program code, and the inventors are currently registering the software and program implementing this evaluation method for software copyright (titled: Downhole Choke Analysis Software under Multiple Operating Conditions). Figure 4 This is a screenshot of part of the code for the system's login page.

[0019] like Figure 1 As shown, it includes: The user interface layer is used to set environmental parameters and throttle valve parameters. This layer includes input modules for user interaction, allowing users to input required environmental parameters, initial values ​​for throttle valve parameters, etc., for logical calculations and data storage.

[0020] The logic calculation layer provides logic program support, iteratively calculates wellbore pressure and temperature, and completes the evaluation of the throttle valve installation depth. This logic calculation layer can use parameters input from the user interface layer and solve for wellbore pressure, temperature distribution, and throttle valve cooling and pressure reduction through iteration.

[0021] The data layer stores data and provides data support for the logic layer. It contains numerical values ​​obtained after computation, calculation results, and recorded data from user interactions. It provides data retrieval and stores calculation results for the logic layer, and provides guidance on calculation results and records user data for the user interface layer.

[0022] The user interface layer contains multiple input modules that allow users to interact with the system. Users input the environmental parameters and initial values ​​of the throttle valve parameters required for the calculation, which are then used for subsequent logical calculations and data storage. Figure 1 The dashed box contains pre-defined general values, which users can adjust based on actual site conditions. The logic calculation layer contains the main calculation formulas and code, using known parameters to iteratively solve for wellbore pressure, temperature distribution, and throttle valve temperature and pressure reduction. The data layer contains the values ​​of important parameters (compressibility coefficient, viscosity) obtained after calculation, the calculation results, and user-recorded data. This layer provides data access and stores calculation results for the logic calculation layer, and also provides calculation result guidance and records user data for the user interface layer.

[0023] During evaluation, the user interface layer passes the input parameters to the logic calculation layer. The logic calculation layer performs calculations based on the data passed from the user interface layer and / or by calling the data stored in the data layer. The logic calculation layer stores the calculation results in the data layer. The user interface layer displays the data output by the logic calculation layer and stored in the data layer in graphical or textual form.

[0024] like Figure 2 As shown, when using the user interface layer for evaluation, the specific flow of data interaction between the user interface layer, the logic calculation layer, and the data layer (the specific steps of system evaluation) is as follows: Step 1: Set the gas well depth, working cylinder diameter, initial pressure, and initial temperature through the user interface layer.

[0025] Step 2: Set CO2 content and production parameters through the user interface layer.

[0026] Step 3: Set the installation depth and throttle nozzle diameter of throttle valve one and throttle valve two through the user interface layer. In steps 1-3 above, the input parameters are all data from the original well (i.e., the well to be evaluated) that needs to be constructed. These data have been continuously recorded since the well began production. When using the evaluation system of this embodiment to evaluate the downhole throttling valve throttling and installation depth of the well, those skilled in the art can directly use the original recorded data of the well without any creative effort.

[0027] Step 4: Submit the data set in Steps 1-3.

[0028] The parameters input through the user interface layer are submitted and stored in the data layer. The subsequent logic calculation layer can directly call these data to perform logical judgments and calculations.

[0029] Step 5: Determine whether the flow rate of throttle valve one reaches the critical flow of throttle valve one; if it does, proceed to step 6; if it does not, proceed to step 8.

[0030] Step 6: Determine whether the preset target pressure has reached the critical flow of the throttle valve. If it is greater than the critical flow, proceed to step 2 and re-enter the production allocation. If it is not greater than the critical flow, proceed to step 7.

[0031] The target pressure mentioned above is input by the user through the user interface layer, which is the pressure value that the user wants to reduce the pressure to when designing the throttle valve and the installation depth. Since the throttle valve may reduce the pressure too much and cause critical flow, the pressure reduction effect when the critical flow is not reached can be shown by manually inputting the value by the user. If the critical flow is still reached by manually inputting the value, it is necessary to avoid this by reducing the production capacity, increasing the throttle valve nozzle diameter, or reducing the installation depth.

[0032] Step 7, enter and submit target pressure one.

[0033] Input the target pressure through the user interface layer, submit a candidate, and store it in the data layer.

[0034] Step 8: Determine if the depth of the second throttle valve is 0; if it is not 0, proceed to step 9; if it is 0, proceed to step 12.

[0035] Step 9: Determine whether the flow rate of throttle valve 2 has reached the critical flow of throttle valve 2; if it has, proceed to step 10; if it has not, proceed to step 12.

[0036] Step 10: Determine whether the preset target pressure 2 has reached the critical flow of the throttle valve 2; if it is greater than the critical flow, proceed to step 2 and re-enter the production allocation; if it is not greater than the critical flow, proceed to step 11.

[0037] The target pressure mentioned above is input by the user through the user interface layer, which is the pressure value that the user wants to reduce the pressure to when designing the throttle valve and the installation depth. Since the throttle valve may reduce the pressure too much and cause critical flow, the pressure reduction effect when the critical flow is not reached can be shown by manually inputting the value by the user. If the critical flow is still reached by manually inputting the value, it is necessary to avoid this by reducing the production capacity, increasing the throttle valve nozzle diameter, or reducing the installation depth.

[0038] Step 11, input and submit target pressure two as a candidate.

[0039] Step 12, output the result.

[0040] By default, users only need to input well depth, initial pressure, initial temperature, wellbore production, installation depth of choke valve one, choke nozzle diameter of choke valve one, installation depth of choke valve two, and choke nozzle diameter of choke valve two through the user interface layer to obtain the changes in gas well pressure and temperature with well depth, as well as the pressure and temperature reduction of the choke valves. When the choke nozzle diameter of choke valve one or choke valve two is too small or the oil and gas production is too large, the choke valve throttling may reach the critical flow. At this time, the pressure change downstream of the choke nozzle has no effect on the gas well production. Users can manually input the downstream pressure and submit the data to obtain the choke valve throttling pressure and temperature reduction under the target downstream pressure, and make further judgments based on the results.

[0041] In steps 5 and 9, when determining whether the flow rate of the corresponding throttle valve has reached the critical flow of the corresponding throttle valve, the determination method is as follows: like When this happens, the critical flow is reached; like If so, the critical flow has not been reached; in, Indicates the upstream pressure of the throttle nozzle. Indicates the downstream pressure of the throttle nozzle; This represents the gas adiabatic index, with a value of 1.3.

[0042] In steps 6 and 10, when determining whether the corresponding target pressure has reached the critical flow of the corresponding throttle valve, the determination method is as follows: like If the target pressure is within a critical flow range, then the target pressure is in a critical flow range; otherwise, the target pressure is in a non-critical flow range.

[0043] like Figure 3 As shown, the specific steps taken by this logic computation layer during logic computation are as follows: Step S1: Input initial parameters; Input initial parameters, including initial pressure at the bottom of the wellbore, initial temperature at the bottom of the wellbore, desired production rate, well depth, installation depth of choke valve one, installation depth of choke valve two, diameter of choke valve one nozzle, diameter of choke valve two nozzle, wellbore diameter, and CO2 content (the value of the compressibility coefficient Z is related to this CO2 content).

[0044] Step S2: Calculate the pressure gradient and loss before the throttle valve 1. Calculate the outlet pressure of the infinitesimal segment based on its length. And the value of pressure loss;

[0045] ; in, This represents the initial pressure at the bottom of the wellbore (of course, in the first calculation, it represents the initial pressure at the bottom of the wellbore; in subsequent iterations, it represents the pressure calculated before the corresponding iteration). Indicates loss due to gravity. Indicates friction loss. Indicates kinetic energy loss; In calculating loss , and When the depth is related to the initial depth of the micro-element, the specific calculation formula is as follows: ; ; ; in, This indicates the starting depth value of the selected micro-element. This represents the endpoint depth value of the selected micro-element segment. Indicates the density of oil and gas. Represents gravitational acceleration. Indicates the angle between the pipe and the horizontal line. Indicates the coefficient of friction. Indicates the dynamic viscosity of oil and gas. This indicates the diameter of the oil pipe.

[0046] Step S3: Compare the loss deviation of the throttle valve; The loss value obtained in step S2 The loss value is compared with a preset deviation value; if the loss value is less than or equal to the deviation value, proceed to step S5 and record the current outlet pressure. Otherwise, proceed to step S4.

[0047] Step S4: Iteratively correct the loss value of the throttle valve; The loss value obtained in step S2 Replace the preset deviation value and re-enter step S3 for iteration until the condition is met and proceed to step S5.

[0048] Step S5: Calculate the inlet temperature of throttle valve one; Calculate the inlet temperature of throttle valve one based on the initial temperature of the current micro-element segment. The calculation formula is: ; ; in, This represents the initial temperature of the current micro-element segment (i.e., the initial temperature of the first micro-element segment - the initial temperature of the wellbore bottom, and the temperature after throttling obtained by iterative solution according to steps S2-S7 (the temperature after throttling of the previous micro-element segment is the initial temperature of the next micro-element segment)). This indicates the starting depth value of the selected micro-element. This represents the endpoint depth value of the selected micro-element segment. This represents the unit change in oil and gas temperature. This represents the length of a unit tubular element within a micro-element segment. represents the wellbore diameter, Indicates the overall heat transfer coefficient. Indicates the thermal conductivity of the formation. Represents a dimensionless time function. Indicates the number of days. Indicates fluid temperature. This indicates the original temperature of the formation. This represents the Joule-Thomson coefficient. Indicates the pressure gradient. Indicates the coefficient of friction. Indicates the oil and gas flow rate. This indicates the specific heat capacity at constant pressure.

[0049] Step S6, Depth determination of throttle valve; Determine whether the currently calculated depth of the micro-element segment reaches the preset installation depth of the throttle valve; if not, proceed to step S2; if so, proceed to step S7.

[0050] Step S7: Calculate the pressure and temperature reduction of the throttle valve. Calculate the pressure after throttling. Temperature after throttling The specific calculation formula is as follows: ; ; in, Indicates the adiabatic index of oil and gas. Indicates the relative density of oil and gas. This represents the gas compressibility coefficient at the pressure before throttling; This indicates a desired output; Indicates the diameter of the throttle nozzle.

[0051] Step S8: Calculate the pressure gradient and loss before the valve of throttle valve 2; Using the temperature and pressure after throttling by throttling valve one as the initial parameters for throttling valve two, calculate the pressure gradient and loss before throttling valve two; the calculation formula is: ; in, Indicates loss due to gravity. Indicates friction loss. This indicates the loss of kinetic energy.

[0052] Step S9: Compare the two loss deviations of the throttle valve; The loss value obtained in step S8 The loss value is compared with a preset deviation value; if the loss value is less than or equal to the deviation value, proceed to step S11 and record the current outlet pressure. Otherwise, proceed to step S10.

[0053] Step S10: Iteratively correct the loss value of the second throttle valve; The loss value obtained in step S8 Replace the preset deviation value and re-enter step S9 for iteration until the condition is met and proceed to step S11.

[0054] Step S11: Calculate the inlet temperature of throttle valve two; The formula for calculating the inlet temperature of valve 2 is the same as that in step S5.

[0055] Step S12: Determine the number of throttle valves; Determine if the number of throttle valves is 1; if yes, proceed to step S15; otherwise, proceed to step S13.

[0056] Step S13, Depth determination of throttle valve II; Determine whether the currently calculated depth of the micro-element segment reaches the preset installation depth of the second throttle valve; if not, proceed to step S8; if so, proceed to step S14.

[0057] Step S14: Calculate the pressure and temperature drop of the second throttle valve; The formula for calculating the pressure and temperature drop of the throttle valve is the same as that in step S7.

[0058] Step S15: Output the result.

[0059] Repeat steps S2-S5 and S8-S11 until the entire well section has been traversed; finally, output the evaluation results. The evaluation results include the pressure distribution curve of the entire wellbore, the temperature distribution curve of the entire wellbore, the pressure and temperature before and after throttling of each throttling valve, the determination of whether the throttling nozzle has reached the critical flow, and the recommended throttling nozzle diameter and installation depth.

Claims

1. A system for evaluating the throttling and installation depth of a downhole throttle valve, characterized in that, include: The user interface layer is used to set environmental parameters and throttle valve parameters; The logic calculation layer provides logic program support, iteratively calculates wellbore pressure and temperature, and completes the evaluation of the throttle valve installation depth; The data layer is used to store data and provide data support for the logic layer. During evaluation, the user interface layer passes the input parameters to the logic calculation layer. The logic calculation layer performs calculations based on the data passed from the user interface layer and / or by calling the data stored in the data layer. The logic calculation layer stores the calculation results in the data layer. The user interface layer displays the data output by the logic calculation layer and stored in the data layer in graphical or textual form.

2. The evaluation system for throttling and installation depth of a downhole throttle valve as described in claim 1, characterized in that, The specific steps for system evaluation are as follows: Step 1: Set the gas well depth, working cylinder diameter, initial pressure, and initial temperature through the user interface layer; Step 2: Set CO2 content and production parameters through the user interface layer; Step 3: Set the installation depth and throttle nozzle diameter of throttle valve one and throttle valve two through the user interface layer; Step 4: Submit the data set in steps 1-3; Step 5: Determine whether the flow rate of throttle valve one has reached the critical flow of throttle valve one; if it has, proceed to step 6; if it has not, proceed to step 8. Step 6: Determine whether the preset target pressure has reached the critical flow of the throttle valve; if it is greater than the critical flow, proceed to step 2 and re-enter the production allocation. If the flow rate is not greater than the critical flow rate, proceed to step 7. Step 7, input and submit target pressure one as a candidate; Step 8: Determine if the depth of the second throttle valve is 0; if it is not 0, proceed to step 9; if it is 0, proceed to step 12. Step 9: Determine whether the flow rate of throttle valve 2 has reached the critical flow of throttle valve 2; if it has, proceed to step 10; if it has not, proceed to step 12. Step 10: Determine whether the preset target pressure 2 has reached the critical flow of the throttle valve 2; if it is greater than the critical flow, proceed to step 2 and re-enter the production allocation. If the flow rate is not greater than the critical flow rate, proceed to step 11. Step 11, input and submit target pressure two as a candidate; Step 12, output the result.

3. The evaluation system for throttling and installation depth of a downhole throttle valve as described in claim 2, characterized in that, In steps 5 and 9, when determining whether the flow rate of the corresponding throttle valve has reached the critical flow of the corresponding throttle valve, the determination method is as follows: like When this happens, the critical flow is reached; like If so, the critical flow has not been reached; in, Indicates the upstream pressure of the throttle nozzle. Indicates the downstream pressure of the throttle nozzle; This represents the gas adiabatic index, with a value of 1.

3.

4. The evaluation system for throttling and installation depth of a downhole throttle valve as described in claim 2, characterized in that, In steps 6 and 10, when determining whether the corresponding target pressure has reached the critical flow of the corresponding throttle valve, the determination method is as follows: like If the target pressure is within a critical flow range, then the target pressure is in a critical flow range; otherwise, the target pressure is in a non-critical flow range.

5. The evaluation system for throttling and installation depth of a downhole throttle valve as described in claim 1, characterized in that, The specific steps taken by the logic computation layer when performing logic computation are as follows: Step S1: Input initial parameters; Input initial parameters, including initial pressure at the bottom of the wellbore, initial temperature at the bottom of the wellbore, desired production rate, well depth, installation depth of choke valve one, installation depth of choke valve two, diameter of choke valve one nozzle, diameter of choke valve two nozzle, wellbore diameter, and CO2 content. Step S2: Calculate the pressure gradient and loss before the throttle valve 1. Calculate the outlet pressure of the infinitesimal segment based on its length. And the value of pressure loss; ； in, This indicates the initial pressure at the bottom of the wellbore. Indicates loss due to gravity. Indicates friction loss. Indicates kinetic energy loss; Step S3: Compare the loss deviation of the throttle valve; The loss value obtained in step S2 The loss value is compared with a preset deviation value; if the loss value is less than or equal to the deviation value, proceed to step S5 and record the current outlet pressure. Otherwise, proceed to step S4; Step S4: Iteratively correct the loss value of the throttle valve; The loss value obtained in step S2 Replace the preset deviation value and re-enter step S3 for iteration until the condition is met and proceed to step S5; Step S5: Calculate the inlet temperature of throttle valve one; Calculate the inlet temperature of throttle valve one based on the initial temperature of the current micro-element segment. The calculation formula is: ； ； in, This indicates the initial temperature of the current infinitesimal segment. This indicates the starting depth value of the selected micro-element. This represents the endpoint depth value of the selected micro-element segment. This represents the unit change in oil and gas temperature. This represents the length of a unit tubular element within a micro-element segment. represents the wellbore diameter, Indicates the overall heat transfer coefficient. Indicates the thermal conductivity of the formation. Represents a dimensionless time function. Indicates the number of days. Indicates fluid temperature. This indicates the original temperature of the formation. This represents the Joule-Thomson coefficient. Indicates the pressure gradient. Indicates the coefficient of friction. Indicates the oil and gas flow rate. This indicates the specific heat capacity at constant pressure. Step S6, Depth determination of throttle valve; Determine whether the currently calculated depth of the micro-element segment reaches the preset installation depth of the throttle valve; if not, proceed to step S2; if so, proceed to step S7. Step S7: Calculate the pressure and temperature reduction of the throttle valve. Calculate the pressure after throttling. Temperature after throttling The specific calculation formula is as follows: ； ； in, Indicates the adiabatic index of oil and gas. Indicates the relative density of oil and gas. This represents the gas compressibility coefficient at the pressure before throttling; This indicates a desired output; Indicates the diameter of the throttle nozzle; Step S8: Calculate the pressure gradient and loss before the valve of throttle valve 2; Using the temperature and pressure after throttling by throttling valve one as the initial parameters for throttling valve two, calculate the pressure gradient and loss before throttling valve two; the calculation formula is: ； in, Indicates loss due to gravity. Indicates friction loss. Indicates kinetic energy loss; Step S9: Compare the two loss deviations of the throttle valve; The loss value obtained in step S8 The loss value is compared with a preset deviation value; if the loss value is less than or equal to the deviation value, proceed to step S11 and record the current outlet pressure. Otherwise, proceed to step S10; Step S10: Iteratively correct the loss value of the second throttle valve; The loss value obtained in step S8 Replace the preset deviation value and re-enter step S9 for iteration until the condition is met and proceed to step S11; Step S11: Calculate the inlet temperature of throttle valve two; The formula for calculating the inlet temperature of valve 2 is the same as that in step S5; Step S12: Determine the number of throttle valves; Determine if the number of throttle valves is 1; if yes, proceed to step S15; otherwise, proceed to step S13. Step S13, Depth determination of throttle valve II; Determine whether the currently calculated depth of the micro-element segment has reached the preset installation depth of the second throttle valve; if not, proceed to step S8; if so, proceed to step S14. Step S14: Calculate the pressure and temperature drop of the second throttle valve; The calculation formula for the pressure and temperature drop of the second throttle valve is the same as that in step S7. Step S15, output the result; Repeat steps S2-S5 and S8-S11 until the entire well section has been traversed; finally, output the evaluation results. The evaluation results include the pressure distribution curve of the entire wellbore, the temperature distribution curve of the entire wellbore, the pressure and temperature before and after throttling of each throttling valve, the determination of whether the throttling nozzle has reached the critical flow, and the recommended throttling nozzle diameter and installation depth.

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