A salt cavern natural gas underground storage natural gas control optimization method and system

Abstract

The application discloses a salt cave natural gas underground storage natural gas control optimization method and system, and relates to the field of salt cave natural gas control. The method comprises the following steps: a series injection method is used to inject natural gas into multiple cavities of a salt cave natural gas underground storage in real time, a first temperature value and a first pressure value of natural gas in any cavity are collected in real time, when the first temperature value and the first pressure value are in a first preset cavity condition, a control instruction is sent to adjust the current cavity injection state in real time until the injection into the any cavity is completed, a current second temperature value and a current second pressure value of the natural gas in the any cavity collected when the injection is completed are used to calculate the storage amount of the any cavity, and the injection optimization of the any cavity is completed. The method solves the problem that the injection and production process of each cavity in the storage lacks unified deployment, and plans and manages each cavity in the storage area, improves the cavity working gas amount, and prolongs the service life of the salt cavity.

Description

Technical Field

[0001] This invention relates to the field of salt cavern natural gas control, and more particularly to a method and system for optimizing natural gas control in underground salt cavern natural gas storage facilities. Background Technology

[0002] Against the backdrop of the national strategy of "peak carbon and carbon neutrality", natural gas, as a clean energy source, occupies an increasingly important position in the national energy sector. As an important supporting link in the natural gas production, supply, storage and sales system, the construction and promotion of gas storage facilities has become an important measure for the country to ensure people's livelihood and regional energy security.

[0003] Salt cavern natural gas underground storage is a type of gas storage facility, consisting of multiple independent underground salt karst chambers that are centrally monitored and regulated from the surface. During off-peak gas consumption periods, excess natural gas is injected into the underground salt karst chambers for storage; during peak gas consumption periods, natural gas is extracted from the underground salt karst chambers to meet the city's peak gas demand. Salt cavern natural gas underground storage facilities have advantages such as good sealing, flexible and convenient gas injection and extraction, large peak-shaving gas volume, and a high proportion of working gas, making them suitable for use as short-term peak-shaving gas storage facilities. During the operation of the gas storage facility, due to the differences in the structure, thermal state, and operational constraints of each chamber, unreasonable allocation of injection and extraction volumes in each individual chamber during peak-shaving injection and extraction may lead to a reduction in the chamber capacity or even premature failure of the chamber. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for optimizing natural gas control in salt cavern natural gas underground storage facilities, addressing the shortcomings of existing technologies.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0006] A method for optimizing natural gas control in a salt cavern natural gas underground storage facility, comprising:

[0007] Natural gas is injected into multiple cavities of the salt cavern natural gas underground storage facility in real time using a series injection method;

[0008] The system collects the first temperature and first pressure values ​​of natural gas in any given cavity in real time. When the first temperature and first pressure values ​​are within the first preset cavity conditions, it sends a control command to adjust the current cavity gas injection status in real time until the gas injection into any given cavity is completed. Based on the current second temperature and current second pressure values ​​of natural gas in any given cavity collected when the gas injection is completed, the inventory of any given cavity is calculated, thus completing the gas injection optimization of any given cavity.

[0009] The beneficial effects of this invention are: the use of series gas injection is expected to increase the working gas volume of a single chamber by about 3.5%; with the implementation of effective monitoring and control, the gas storage can obtain the maximum gas storage capacity, improve the operating efficiency of the gas storage, reduce the risk of premature failure of the salt chamber due to blind injection and extraction, maximize the safety of the gas storage, and extend the service life of the gas storage.

[0010] This solution addresses the lack of unified coordination in the injection and extraction processes of individual gas chambers within a gas storage facility. It enables comprehensive management of individual gas chambers within the storage area, increases the working gas volume of the chambers, and extends the service life of the salt chambers.

[0011] Furthermore, the step of sending a control command when the first temperature value and the first pressure value are within the first preset cavity conditions specifically includes:

[0012] If the first temperature value is not greater than the maximum daily temperature rise, a command to continue gas injection is issued.

[0013] When the first temperature value is greater than the maximum daily temperature rise, an instruction to reduce the gas injection rate is issued.

[0014] When the first pressure value is not greater than the maximum pressure, a command to continue gas injection is issued;

[0015] When the first pressure value is greater than the maximum pressure, a stop gas injection command is issued.

[0016] The beneficial effects of adopting the above-mentioned further scheme are as follows: If the temperature rise constraint is not met when the minimum allowable pressure of the gas storage cavity is reached, the storage capacity of the gas storage cavity will be reduced by 3.5%. However, by using series sequential gas injection, the gas storage cavity can obtain a larger gas storage capacity while meeting the maximum allowable temperature rise constraint requirement of the gas storage cavity, thus improving the operating efficiency of the gas storage facility.

[0017] Furthermore, it also includes: after stopping the current cavity injection, performing the next cavity injection, until all cavities are injected.

[0018] Furthermore, it also includes:

[0019] The parallel gas extraction method is used to extract natural gas from multiple chambers in real time;

[0020] Real-time acquisition of the third temperature and third pressure values ​​of natural gas in each cavity;

[0021] Send control commands to adjust the gas sampling status of each second cavity in real time to meet the preset conditions until gas sampling is completed. The preset conditions are: the third temperature value and the third pressure value are within the conditions of the second preset cavity.

[0022] Based on the fourth temperature and fourth pressure values ​​of the natural gas collected in each cavity at the end of gas extraction, the storage capacity of each cavity at the end of gas extraction is calculated, thus completing the gas extraction optimization.

[0023] The beneficial effects of adopting the above-mentioned further scheme are: by parallel mining, this scheme can ensure that the maximum allowable pressure drop meets the constraint requirements when the minimum allowable pressure of the cavity is reached, thus avoiding creep deformation of the cavity, and can also obtain the maximum natural gas output, thereby improving the operating efficiency of the gas storage facility.

[0024] Furthermore, the step of sending a control command when the third temperature value and the third pressure value are within the second preset cavity conditions specifically includes:

[0025] When the third pressure value is greater than or equal to the maximum pressure drop, an instruction to reduce the gas extraction rate is issued;

[0026] When the third pressure value is less than the maximum pressure drop, a command to continue gas extraction is issued;

[0027] When the third pressure value is less than the minimum pressure, a command to continue gas sampling is issued.

[0028] When the third pressure value is greater than or equal to the minimum pressure, a stop gas extraction command is issued.

[0029] The beneficial effects of adopting the above-mentioned further scheme are: This scheme collects pressure, temperature and flow data in real time during the gas injection and gas extraction process, compares them with the set temperature and pressure in real time, and provides an adjustment scheme based on the actual analysis data in case of abnormalities. It also sends relevant instructions to the controller, and adjusts the gas injection and gas extraction rates to keep the operation process within a safe and controllable range, thus ensuring safe operation.

[0030] Another technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0031] A natural gas control optimization system for a salt cavern natural gas underground storage facility includes: a gas injection module, a first data acquisition module, a command control module, and a calculation module;

[0032] The gas injection module is used to inject natural gas into multiple cavities of the salt cavern natural gas underground storage facility in real time using a series gas injection method;

[0033] The first acquisition module is used to acquire the first temperature value and the first pressure value of natural gas in any cavity in real time. The instruction control module is used to send an adjustment instruction to adjust the current gas injection state of the cavity in real time when the first temperature value and the first pressure value are at the first preset cavity conditions, until the gas injection into the cavity is completed. The calculation module is used to calculate the inventory of the cavity based on the current second temperature value and the current second pressure value of natural gas in the cavity acquired when the gas injection is completed, and to optimize the gas injection of the cavity.

[0034] The beneficial effects of this invention are: the use of series gas injection is expected to increase the working gas volume of a single chamber by about 3.5%; with the implementation of effective monitoring and control, the gas storage can obtain the maximum gas storage capacity, improve the operating efficiency of the gas storage, reduce the risk of premature failure of the salt chamber due to blind injection and extraction, maximize the safety of the gas storage, and extend the service life of the gas storage.

[0035] This solution addresses the lack of unified coordination in the injection and extraction processes of individual gas chambers within a gas storage facility. It enables comprehensive management of individual gas chambers within the storage area, increases the working gas volume of the chambers, and extends the service life of the salt chambers.

[0036] Furthermore, the instruction control module is specifically used to issue an instruction to continue gas injection when the first temperature value is not greater than the maximum daily temperature rise;

[0037] When the first temperature value is greater than the maximum daily temperature rise, an instruction to reduce the gas injection rate is issued.

[0038] When the first pressure value is not greater than the maximum pressure, a command to continue gas injection is issued;

[0039] When the first pressure value is greater than the maximum pressure, a stop gas injection command is issued.

[0040] The beneficial effects of adopting the above-mentioned further scheme are as follows: If the temperature rise constraint is not met when the minimum allowable pressure of the gas storage cavity is reached, the storage capacity of the gas storage cavity will be reduced by 3.5%. However, by using series sequential gas injection, the gas storage cavity can obtain a larger gas storage capacity while meeting the maximum allowable temperature rise constraint requirement of the gas storage cavity, thus improving the operating efficiency of the gas storage facility.

[0041] Furthermore, it also includes a continuous gas injection module, used to perform the next gas injection in a cavity after stopping the current cavity injection, until all cavities are fully injected.

[0042] Furthermore, it also includes a gas extraction module for real-time gas extraction from multiple chambers using a parallel gas extraction method;

[0043] Real-time acquisition of the third temperature and third pressure values ​​of natural gas in each cavity;

[0044] Send control commands to adjust the gas sampling status of each second cavity in real time to meet the preset conditions until gas sampling is completed. The preset conditions are: the third temperature value and the third pressure value are within the conditions of the second preset cavity.

[0045] Based on the fourth temperature and fourth pressure values ​​of the natural gas collected in each cavity at the end of gas extraction, the storage capacity of each cavity at the end of gas extraction is calculated, thus completing the gas extraction optimization.

[0046] The beneficial effects of adopting the above-mentioned further scheme are: by parallel mining, this scheme can ensure that the maximum allowable pressure drop meets the constraint requirements when the minimum allowable pressure of the cavity is reached, thus avoiding creep deformation of the cavity, and can also obtain the maximum natural gas output, thereby improving the operating efficiency of the gas storage facility.

[0047] Furthermore, the gas sampling module is specifically used to issue a command to reduce the gas sampling rate when the third pressure value is greater than or equal to the maximum pressure drop;

[0048] When the third pressure value is less than the maximum pressure drop, a command to continue gas extraction is issued;

[0049] When the third pressure value is less than the minimum pressure, a command to continue gas sampling is issued.

[0050] When the third pressure value is greater than or equal to the minimum pressure, a stop gas extraction command is issued.

[0051] The beneficial effects of adopting the above-mentioned further scheme are: the temperature and pressure of each cavity are different, and the appropriate gas injection and production rate can be calculated based on the different temperature and pressure data of each cavity. The gas production rate of each well is different, but the final total gas production meets the requirements, reducing capacity loss, avoiding hydrate formation, maintaining cavity stability, and ensuring safe and stable operation.

[0052] This solution collects pressure, temperature, and flow data in real time during gas injection and extraction, compares them with the set temperature and pressure, and provides adjustment plans based on actual analysis data in case of abnormalities. It also sends relevant instructions to the controller to adjust the gas injection and extraction rates to keep the operation within a safe and controllable range, thus ensuring safe operation.

[0053] The advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0054] Figure 1 A flowchart illustrating a method for optimizing natural gas control in a salt cavern natural gas underground storage facility, provided as an embodiment of the present invention;

[0055] Figure 2A structural block diagram of a natural gas control optimization system for a salt cavern natural gas underground storage facility is provided as an embodiment of the present invention;

[0056] Figure 3 Flowcharts for optimizing the gas injection process control are provided for other embodiments of the present invention;

[0057] Figure 4 A flow chart for optimizing gas extraction process control is provided for other embodiments of the present invention;

[0058] Figure 5 A schematic diagram of a single cavity of a salt cavern-type underground natural gas storage facility provided for other embodiments of the present invention;

[0059] Figure 6 A schematic diagram of gas injection cavity temperature data provided for other embodiments of the present invention;

[0060] Figure 7 A schematic diagram of gas sampling cavity pressure data provided for other embodiments of the present invention. Detailed Implementation

[0061] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0062] like Figure 1 The diagram illustrates a natural gas control optimization method for a salt cavern natural gas underground storage facility, as provided in this embodiment of the invention. It should be noted that the control optimization can be divided into an injection process and a production process, which are independent of each other and both are methods for natural gas control optimization in salt cavern natural gas underground storage facilities. In the original injection and production process, a gas injection and production plan was first set, and the injection and production flow rates were set on-site according to the plan. Pressure and temperature changes were monitored to analyze and confirm whether the injection and production met the plan requirements, and adjustments were made promptly to ensure operation. The optimized plan involves installing a monitoring module at the injection and production wellhead to collect pressure, temperature, and flow rate data in real time during the injection and production process. This data is compared in real time with the temperature and pressure settings set in the monitoring module. In case of abnormalities, the control module will provide an adjustment plan based on the actual analysis data and send relevant instructions to the controller. By adjusting the injection and production rates, the operation process is kept within a safe and controllable range, ensuring operational safety.

[0063] The control optimization methods include: S1, using a series gas injection method to inject natural gas into multiple cavities of the salt cavern natural gas underground storage facility in real time;

[0064] It should be noted that the temperature and pressure of natural gas in the well cavity are monitored through the online monitoring module. The online monitoring module is an information acquisition device mainly installed at the wellhead or bottom of the well, used to monitor the pressure, temperature and rate data in real time during the gas injection and gas production process.

[0065] In another implementation, the maximum permissible daily temperature rise and maximum permissible pressure within the injection cavity are input into the control module. The control module, based on stability analysis, determines the safe operating ranges for pressure, temperature, and injection / production rates during gas injection and production. This data is then input into the control module. During gas injection and production, if any deviation from the set safe range occurs, the control module performs calculations and analysis based on real-time data, makes timely adjustments, and sends adjustment commands to the execution module.

[0066] S2, real-time acquisition of the first temperature value and the first pressure value of natural gas in any cavity; wherein, the first temperature value and the first pressure value are the temperature rise and pressure values ​​of natural gas in the cavity monitored by the online monitoring module;

[0067] S3, when the first temperature value and the first pressure value are within the first preset cavity conditions, a control command is sent to adjust the current cavity gas injection state in real time until gas injection into any of the cavities is completed; wherein, the first preset cavity conditions mean that the first temperature value and the first pressure value are within the range of preset temperature and pressure value requirements. The command may include: reducing or increasing the gas injection / production rate, or closing or opening the wellhead valve.

[0068] In one embodiment, such as Figure 3 As shown, S3 specifically includes: if the temperature rise of the natural gas in the melting cavity monitored by the online monitoring module does not exceed the maximum allowable temperature rise per day, the control module sends an instruction to the execution module to continue injecting gas;

[0069] If the temperature rise of the natural gas in the cavity monitored by the online monitoring module exceeds the maximum allowable temperature rise per day, the control module sends an instruction to the execution module to reduce the gas injection rate;

[0070] If the pressure of natural gas in the cavity monitored by the online monitoring module does not exceed the maximum allowable pressure, the control module sends a command to the execution module to continue injecting gas;

[0071] If the pressure of natural gas in the cavity monitored by the online monitoring module exceeds the maximum allowable pressure, the control module sends a command to the execution module to stop the gas injection in that cavity and proceed to the next cavity for gas injection. It should be noted that during the gas injection process, multiple cavities are injected in batches. After one cavity is filled with natural gas, the injection will be moved to other unfilled cavities until all cavities are filled with natural gas.

[0072] S4. Calculate the inventory level of any one of the natural gas chambers based on the current second temperature and second pressure values ​​collected when gas injection is completed, thus optimizing the gas injection of any one of the chambers. The second temperature and second pressure values ​​can be the temperature and pressure values ​​of the chamber after gas injection. It should be noted that the achievable storage capacity of a single chamber can be obtained based on the maximum allowable pressure inside the chamber and the corresponding chamber temperature.

[0073] This scheme, using series gas injection, is expected to increase the working gas volume of a single chamber by approximately 3.5%. With the implementation of effective monitoring and control, the gas storage facility will achieve its maximum storage capacity, improve operational efficiency, reduce the risk of premature failure of the salt chamber due to indiscriminate injection and extraction, maximize the safety of the gas storage facility, and extend its service life.

[0074] This solution addresses the lack of unified coordination in the injection and extraction processes of individual gas chambers within a gas storage facility. It enables comprehensive management of individual gas chambers within the storage area, increases the working gas volume of the chambers, and extends the service life of the salt chambers.

[0075] In one embodiment, the gas extraction process employs a parallel extraction method, with gas extraction occurring simultaneously in each gas storage cavity within the storage facility. Gas injection and extraction are two independent processes; gas injection cannot occur during extraction, and vice versa. Multiple cavities are involved in both extraction and extraction simultaneously, not just a single cavity. For example, five cavities may be injecting gas simultaneously, while ten cavities may be extracting gas simultaneously.

[0076] In one embodiment, such as Figure 4 As shown, the parallel gas production process may include:

[0077] S11. The online monitoring module monitors the temperature and pressure of natural gas in the cavity.

[0078] S12. Input the minimum allowable pressure of natural gas in the melting chamber and the maximum allowable pressure drop of the melting chamber per day into the control module;

[0079] S13. If the pressure drop of natural gas in the cavity caused by gas production reaches the maximum allowable pressure drop of the cavity per day, the control module sends an instruction to the execution module and feeds it back to the wellhead to reduce the gas production rate.

[0080] If the pressure drop of natural gas in the cavity caused by gas extraction does not reach the maximum allowable pressure drop of the cavity per day, an instruction is sent to the execution module to continue gas extraction;

[0081] If the natural gas pressure in the cavity caused by gas extraction does not reach the minimum allowable pressure, the control module sends a command to the execution module to continue gas extraction; if the natural gas pressure in the cavity caused by gas extraction reaches the minimum allowable pressure, the control module sends a command to the execution module to stop gas extraction.

[0082] S14. The execution module executes the instructions issued by the control module, which may include: continue gas sampling or stop gas sampling.

[0083] S15. Based on the minimum allowable pressure inside the cavity and the cavity temperature corresponding to the minimum allowable pressure, obtain the gas extraction of a single cavity.

[0084] By establishing an injection and production control system for salt cavern natural gas underground storage, the scientific allocation of injection and production volumes for each cavity in the salt cavern can be achieved. A schematic diagram of a single cavity in a salt cavern-type natural gas underground storage facility is shown below. Figure 5 The diagram shows the structural schematic of a single-cavity gas injection and production system in a salt cavern gas storage facility. The cavity of a salt cavern gas storage facility is a hollow space formed in an underground salt layer through water dissolution. Once the cavity reaches a certain volume and shape, it can be used to store natural gas. The cavity is connected to the surface injection and production tree via a wellbore, and then connected to pipelines from the injection and production tree. The salt rock strata are not pure salt rock; they contain interlayers of other rock types. To ensure the cavity's airtightness, sufficient salt and other salt layers are reserved above the cavity as a capping layer to prevent gas leakage. This is expected to increase the working gas volume of a single cavity by approximately 3.5%. With the implementation of effective monitoring and control operations, the gas storage facility can achieve its maximum storage capacity, improve operational efficiency, reduce the risk of premature failure of the salt cavity due to indiscriminate injection and production, maximize the safety of the gas storage facility, and extend its service life. The scientific allocation of gas injection and production volumes for each cavity includes: because the temperature and pressure of each cavity differ, a suitable gas injection and production rate is calculated based on the different temperature and pressure data of each cavity. While the gas production rate varies for each well, the final total gas production volume meets the requirements, reducing capacity loss, preventing hydrate formation, maintaining cavity stability, and ensuring safe and stable operation. Parallel gas production includes simultaneous gas production from multiple cavities. Series gas injection in salt cavern cavities involves injecting gas into multiple cavities simultaneously, filling one cavity before injecting into another, thus continuously injecting gas from one cavity to the next.

[0085] Optionally, in any of the above embodiments, the step of sending a control command when the first temperature value and the first pressure value are at the first preset cavity condition specifically includes:

[0086] If the first temperature value is not greater than the maximum daily temperature rise, a command to continue gas injection is issued.

[0087] When the first temperature value is greater than the maximum daily temperature rise, an instruction to reduce the gas injection rate is issued.

[0088] When the first pressure value is not greater than the maximum pressure, a command to continue gas injection is issued;

[0089] When the first pressure value is greater than the maximum pressure, a stop gas injection command is issued.

[0090] If the temperature rise constraint is not met when the minimum allowable pressure of the gas storage cavity is reached, the capacity of the gas storage cavity will be reduced by 3.5%. However, by using series sequential gas injection, the gas storage cavity can achieve a larger storage capacity and improve the operating efficiency of the gas storage facility while meeting the maximum allowable temperature rise constraint requirement.

[0091] Optionally, in any of the above embodiments, the method further includes: after stopping the current cavity injection, performing the next cavity injection, until all cavities are injected.

[0092] Optionally, in any of the above embodiments, it further includes:

[0093] The parallel gas extraction method is used to extract natural gas from multiple chambers in real time;

[0094] The third temperature and third pressure values ​​of natural gas in each cavity are collected in real time; the third temperature and third pressure values ​​can be monitored by an online monitoring module to monitor the temperature and pressure of natural gas in the cavity.

[0095] The control command is sent to adjust the gas sampling status of each second cavity in real time to meet the preset conditions until the gas sampling is completed. The preset conditions are: the third temperature value and the third pressure value are within the second preset cavity conditions; wherein, the second preset cavity conditions can be that the third temperature value and the third pressure value meet the preset temperature and pressure value requirements.

[0096] Based on the fourth temperature and fourth pressure values ​​of the natural gas collected in each cavity at the end of gas extraction, the storage capacity of each cavity at the end of gas extraction is calculated, thus completing gas extraction optimization. The fourth temperature and fourth pressure values ​​represent the temperature and pressure values ​​of the cavity at the end of gas extraction.

[0097] This scheme, through parallel extraction, ensures that the maximum allowable pressure drop meets the constraints when the minimum allowable pressure of the cavity is reached, thus avoiding creep deformation of the cavity, while also maximizing the natural gas production and improving the operating efficiency of the gas storage facility.

[0098] Optionally, in any of the above embodiments, sending a control command when the third temperature value and the third pressure value are within the second preset cavity conditions specifically includes:

[0099] When the third pressure value is greater than or equal to the maximum pressure drop, an instruction to reduce the gas extraction rate is issued;

[0100] When the third pressure value is less than the maximum pressure drop, a command to continue gas extraction is issued;

[0101] When the third pressure value is less than the minimum pressure, a command to continue gas sampling is issued.

[0102] When the third pressure value is greater than or equal to the minimum pressure, a stop gas extraction command is issued.

[0103] This solution collects pressure, temperature, and flow data in real time during gas injection and extraction, compares them with the set temperature and pressure, and provides adjustment plans based on actual analysis data in case of abnormalities. It also sends relevant instructions to the controller to adjust the gas injection and extraction rates to keep the operation within a safe and controllable range, thus ensuring safe operation.

[0104] In another embodiment, a domestic salt cavern gas storage facility has four cavities. The basic data of the gas storage facility's cavities are shown in Table 1.

[0105]

[0106]

[0107] Table 1

[0108] (1) Gas injection process

[0109] Gas injection is performed sequentially from well 1 according to the wellbore number, and the dynamic changes in wellhead pressure and temperature are monitored by the monitoring module. The control module is set to maintain a gas temperature of 1℃ / 10 days and a maximum allowable pressure of 18.5MPa within the cavitation chamber. Figure 6 As shown;

[0110] Based on the maximum permissible pressure P inside the cavity max Based on the corresponding cavity temperature T, the maximum achievable capacity of a single cavity is obtained using the following formula:

[0111]

[0112] In the formula: Vyx is the volume of a single cavity; Grq is the maximum storage capacity of the natural gas in the cavity at the maximum allowable pressure and temperature T, in m³. 3 ;P max The maximum permissible pressure inside the cavity is given by kPa; T is the temperature of the natural gas inside the cavity by K; and ρ is the density of the natural gas by kg / m³. 3 Zsc is the compressibility factor of the cavity under standard conditions; Tsc is the temperature of the cavity under standard conditions, in K; Psc is the pressure of the cavity under standard conditions, in kPa; A0, B0, C0, D0, E0, a, b, c, d, α, γ are called BWR equation constants, which can be obtained from tables.

[0113] Based on monitoring data, at 0.1×10 6 m 3The injection rate of / d shows that the injection rate satisfies the constraint of a 1°C temperature rise over 10 days. When the maximum allowable pressure of 18.5 MPa is reached, the calculated maximum gas storage capacity is 4117.12 × 10⁴ m³. 3 .

[0114] However, if the injection volume is 0.5 × 10 6 m 3 Gas injection begins at / d. The temperature rise over 10 days is 1.46℃, which does not meet the temperature rise constraint. At this point, the control module issues a command, which is fed back to the wellhead by the execution module to adjust the gas injection rate. Assuming continued gas injection, when the maximum allowable pressure of 18.5MPa is reached, the maximum gas storage capacity that the cavity can achieve, calculated using the following formula, is 3977.68 × 10⁻⁶. 4 m 3 .

[0115]

[0116] Comparing the two operating conditions, the gas storage capacity is reduced:

[0117] (3977.68×10 4 m 3 -4117.12×10 4 m 3 ) / 3977.68×10 4 m 3 =3.5%.

[0118] It is evident that when the minimum allowable pressure of the gas-filled cavity is reached, the storage capacity of the gas-filled cavity will decrease by 3.5% if the temperature rise constraint is not met. However, by using sequential gas injection in series, the gas-filled cavity can achieve a larger storage capacity while meeting the maximum allowable temperature rise constraint requirement, thus improving the operating efficiency of the gas storage facility.

[0119] (2) Gas extraction process

[0120] To meet the city's peak shaving needs of 1.5 × 10 6 m 3 For the / d demand, the control module's control parameters are a maximum allowable pressure drop of 1MPa / day and a minimum allowable pressure of 5.5MPa. A parallel gas production method using four wells simultaneously is adopted. Taking the second well as an example, when the monitored cavity temperature is 45℃ and the cavity pressure is 10MPa, the gas production rate is 0.375×10 6 m 3 Gas extraction begins at / d, meeting the maximum allowable pressure drop constraint, and can be continuously extracted for 14 days, yielding 5.25 × 10⁻⁶ gas. 6 m 3 Natural gas peak-shaving storage capacity. For example... Figure 7 As shown.

[0121] However, if we only consider the second well as 1.5 × 10 6 m 3 According to monitoring data, by the second day of mining, the maximum allowable pressure drop of 1 MPa / d was no longer met. Furthermore, if mining continued, only 4.5 × 10⁻⁶ MPa could be extracted from the cavity when the minimum allowable pressure of 5.5 MPa was reached. 6 m 3 .

[0122] If the gas extraction rate is 0.8 × 10 6 m 3 Gas extraction begins at / d, but can only continue until the 4th day, failing to meet the constraint of a maximum allowable pressure drop of 1 MPa / day. Furthermore, if extraction continues, even at the minimum allowable pressure of 5.5 MPa, the cavity can only extract 4.8 × 10⁻⁶ MPa. 6 m 3 .

[0123] It is evident that simultaneous parallel extraction of four cavities ensures that the maximum allowable pressure drop meets the constraints when the minimum allowable pressure of the cavities is reached, thus preventing creep deformation of the cavities and maximizing the natural gas production, thereby improving the operating efficiency of the gas storage facility.

[0124] In one embodiment, such as Figure 2 As shown, a natural gas control optimization system for a salt cavern natural gas underground storage facility includes: a gas injection module 1101, a first acquisition module 1102, a command control module 1103, and a calculation module 1104.

[0125] The gas injection module 1101 is used to inject natural gas into multiple cavities of the salt cavern natural gas underground storage facility in real time using a series gas injection method;

[0126] The first acquisition module 1102 is used to acquire the first temperature value and the first pressure value of natural gas in any cavity in real time;

[0127] The instruction control module 1103 is used to send an adjustment instruction to adjust the current gas injection state of the cavity in real time when the first temperature value and the first pressure value are at the first preset cavity conditions, until the gas injection into any of the cavities is completed.

[0128] The calculation module 1104 is used to calculate the inventory of any one of the natural gas chambers based on the current second temperature value and the current second pressure value of the natural gas in any one of the chambers collected when the gas injection is completed, and to optimize the gas injection of any one of the chambers.

[0129] This scheme, using series gas injection, is expected to increase the working gas volume of a single chamber by approximately 3.5%. With the implementation of effective monitoring and control, the gas storage facility will achieve its maximum storage capacity, improve operational efficiency, reduce the risk of premature failure of the salt chamber due to indiscriminate injection and extraction, maximize the safety of the gas storage facility, and extend its service life.

[0130] This solution addresses the lack of unified coordination in the injection and extraction processes of individual gas chambers within a gas storage facility. It enables comprehensive management of individual gas chambers within the storage area, increases the working gas volume of the chambers, and extends the service life of the salt chambers.

[0131] Optionally, in any of the above embodiments, the instruction control module 1103 is specifically used to issue an instruction to continue gas injection when the first temperature value is not greater than the maximum daily temperature rise.

[0132] When the first temperature value is greater than the maximum daily temperature rise, an instruction to reduce the gas injection rate is issued.

[0133] When the first pressure value is not greater than the maximum pressure, a command to continue gas injection is issued;

[0134] When the first pressure value is greater than the maximum pressure, a stop gas injection command is issued.

[0135] If the temperature rise constraint is not met when the minimum allowable pressure of the gas storage cavity is reached, the capacity of the gas storage cavity will be reduced by 3.5%. However, by using series sequential gas injection, the gas storage cavity can achieve a larger storage capacity and improve the operating efficiency of the gas storage facility while meeting the maximum allowable temperature rise constraint requirement.

[0136] Optionally, in any of the above embodiments, it further includes: a continuous gas injection module, used to perform the next gas injection in a cavity after stopping the current cavity gas injection, until all cavities are gas injected.

[0137] Optionally, in any of the above embodiments, a gas sampling module is further included, which is used to collect natural gas from multiple chambers in real time using a parallel gas sampling method;

[0138] Real-time acquisition of the third temperature and third pressure values ​​of natural gas in each cavity;

[0139] Send control commands to adjust the gas sampling status of each second cavity in real time to meet the preset conditions until gas sampling is completed. The preset conditions are: the third temperature value and the third pressure value are within the conditions of the second preset cavity.

[0140] Based on the fourth temperature and fourth pressure values ​​of the natural gas collected in each cavity at the end of gas extraction, the storage capacity of each cavity at the end of gas extraction is calculated, thus completing the gas extraction optimization.

[0141] This scheme, through parallel extraction, ensures that the maximum allowable pressure drop meets the constraints when the minimum allowable pressure of the cavity is reached, thus avoiding creep deformation of the cavity, while also maximizing the natural gas production and improving the operating efficiency of the gas storage facility.

[0142] Optionally, in any of the above embodiments, the gas sampling module is specifically used to issue a command to reduce the gas sampling rate when the third pressure value is greater than or equal to the maximum pressure drop;

[0143] When the third pressure value is less than the maximum pressure drop, a command to continue gas extraction is issued;

[0144] When the third pressure value is less than the minimum pressure, a command to continue gas sampling is issued.

[0145] When the third pressure value is greater than or equal to the minimum pressure, a stop gas extraction command is issued.

[0146] The temperature and pressure of each cavity are different. Based on the different temperature and pressure data of each cavity, the appropriate gas injection and production rate is calculated. The gas production rate of each well is different, but the final total gas production meets the requirements, reducing capacity loss, avoiding hydrate formation, maintaining cavity stability, and ensuring safe and stable operation.

[0147] This solution collects pressure, temperature, and flow data in real time during gas injection and extraction, compares them with the set temperature and pressure, and provides adjustment plans based on actual analysis data in case of abnormalities. It also sends relevant instructions to the controller to adjust the gas injection and extraction rates to keep the operation within a safe and controllable range, thus ensuring safe operation.

[0148] It is understood that in some embodiments, some or all of the optional implementation methods described in the above embodiments may be included.

[0149] It should be noted that the above embodiments are product embodiments corresponding to the prior method embodiments. For the description of each optional implementation in the product embodiments, please refer to the corresponding description in the above method embodiments, which will not be repeated here.

[0150] Readers should understand that in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0151] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the method embodiments described above are merely illustrative. For instance, the division of steps is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple steps may be combined or integrated into another step, or some features may be ignored or not executed.

[0152] If the above methods are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0153] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for optimizing natural gas control in a salt cavern natural gas underground storage facility, characterized in that, include: Natural gas is injected into multiple cavities of the salt cavern natural gas underground storage facility in real time using a series injection method; Real-time acquisition of the first temperature and first pressure values ​​of natural gas in any given cavity; When the first temperature value and the first pressure value are within the first preset cavity conditions, a control command is sent to adjust the current cavity gas injection state in real time until gas injection into any of the cavities is completed. The inventory of any one of the natural gas chambers is calculated based on the current second temperature value and the current second pressure value of the natural gas collected when the gas injection is completed, and the gas injection optimization of any one of the chambers is completed. When the first temperature value and the first pressure value are within the first preset cavity conditions, the control command is sent, specifically including: If the first temperature value is not greater than the maximum daily temperature rise, a command to continue gas injection is issued. When the first temperature value is greater than the maximum daily temperature rise, an instruction to reduce the gas injection rate is issued. When the first pressure value is not greater than the maximum pressure, a command to continue gas injection is issued; When the first pressure value is greater than the maximum pressure, a stop gas injection command is issued; This also includes: after stopping the current cavity injection, proceed with the next cavity injection until all cavities have been injected; Also includes: The parallel gas extraction method is used to extract natural gas from multiple chambers in real time; Real-time acquisition of the third temperature and third pressure values ​​of natural gas in each cavity; Send control commands to adjust the gas sampling status of each second cavity in real time to meet the preset conditions until gas sampling is completed. The preset conditions are: the third temperature value and the third pressure value are within the conditions of the second preset cavity. Based on the fourth temperature and fourth pressure values ​​of the natural gas collected in each cavity at the end of gas extraction, the storage capacity of each cavity at the end of gas extraction is calculated, thus completing the gas extraction optimization.

2. The method for optimizing natural gas control in a salt cavern natural gas underground storage facility according to claim 1, characterized in that, When the third temperature value and the third pressure value are within the second preset cavity conditions, a control command is sent, specifically including: When the third pressure value is greater than or equal to the maximum pressure drop, an instruction to reduce the gas extraction rate is issued; When the third pressure value is less than the maximum pressure drop, a command to continue gas extraction is issued; When the third pressure value is less than the minimum pressure, a command to continue gas sampling is issued. When the third pressure value is greater than or equal to the minimum pressure, a stop gas extraction command is issued.

3. A natural gas control optimization system for a salt cavern natural gas underground storage facility, characterized in that, include: The module consists of an air injection module, a first data acquisition module, a command control module, and a calculation module. The gas injection module is used to inject natural gas into multiple cavities of the salt cavern natural gas underground storage facility in real time using a series gas injection method; The first acquisition module is used to acquire the first temperature value and the first pressure value of natural gas in any cavity in real time; when the first temperature value and the first pressure value are within the first preset cavity conditions, a control command is sent to adjust the current cavity gas injection state in real time until the gas injection into any cavity is completed; The calculation module is used to calculate the inventory of any one of the natural gas chambers based on the current second temperature value and the current second pressure value of the natural gas collected when the gas injection is completed, and to optimize the gas injection of any one of the chambers. The instruction control module is specifically used to: issue an instruction to continue gas injection when the first temperature value is not greater than the maximum daily temperature rise; When the first temperature value is greater than the maximum daily temperature rise, an instruction to reduce the gas injection rate is issued. When the first pressure value is not greater than the maximum pressure, a command to continue gas injection is issued; When the first pressure value is greater than the maximum pressure, a stop gas injection command is issued; It also includes: a continuous gas injection module, which is used to perform the next gas injection after stopping the current cavity gas injection, until all cavities are gas injected; It also includes a gas extraction module, which is used to extract natural gas from multiple chambers in real time using a parallel gas extraction method; Real-time acquisition of the third temperature and third pressure values ​​of natural gas in each cavity; Send control commands to adjust the gas sampling status of each second cavity in real time to meet the preset conditions until gas sampling is completed. The preset conditions are: the third temperature value and the third pressure value are within the conditions of the second preset cavity. Based on the fourth temperature and fourth pressure values ​​of the natural gas collected in each cavity at the end of gas extraction, the storage capacity of each cavity at the end of gas extraction is calculated, thus completing the gas extraction optimization.

4. The natural gas control optimization system for a salt cavern natural gas underground storage facility according to claim 3, wherein the gas extraction module is specifically used to issue an instruction to reduce the gas extraction rate when the third pressure value is greater than or equal to the maximum pressure drop; When the third pressure value is less than the maximum pressure drop, a command to continue gas extraction is issued; When the third pressure value is less than the minimum pressure, a command to continue gas sampling is issued. When the third pressure value is greater than or equal to the minimum pressure, a stop gas extraction command is issued.

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