A natural gas wellhead gathering method and system, power supply method and device

Abstract

The application discloses a natural gas wellhead gathering and transportation method and system, a power supply method and device. High-pressure dry gas obtained through high-pressure well products of a gas well wellhead is sent to a differential pressure generator to generate electricity, and low-pressure low-temperature dry gas is output; a part of the low-pressure low-temperature dry gas is electrically heated to obtain high-temperature dry gas reaching a preset temperature, and the high-temperature dry gas is input into a molecular sieve tower to adsorb moisture to obtain high-temperature wet gas; wherein, the electric energy required by electric heating and a molecular sieve tower electric valve is supplied by the differential pressure generator; the high-temperature wet gas and another part of the low-pressure low-temperature dry gas are heat-exchanged to obtain cooled wet gas and reheated dry gas respectively; the cooled wet gas is input into a regenerated gas separator to obtain separated regenerated gas, and the reheated dry gas is mixed with the separated regenerated gas to obtain mixed gas meeting pipeline transportation requirements. The method fully utilizes the formation pressure energy in the natural gas gathering and transportation process, optimizes gathering and transportation energy consumption, realizes wellhead energy self-sufficiency, avoids regenerated gas waste and saves regenerated gas deep dehydration energy consumption.

Description

Technical Field

[0001] This invention relates to the field of oil and gas gathering and transportation technology, and in particular to a natural gas wellhead gathering and transportation method and system, a power supply method and device. Background Technology

[0002] Natural gas wellheads typically have high pressure and are saturated with water, sometimes even containing free water. To meet the requirements of natural gas gathering and transportation in surface engineering, pressure reduction is necessary. To prevent freezing and blockage of the gathering and transportation pipelines due to the temperature drop caused by the Joule-Thomson effect during pressure reduction, a common gathering and transportation process before pressure reduction involves heating, alcohol injection, and dehydration. Heating provides energy by burning natural gas but does not dehydrate the gas, has limited gathering and transportation distance, and consumes a certain amount of natural gas. Alcohol injection (usually ethylene glycol) effectively prevents freezing, but when the water content is high (especially with high free water content), ethylene glycol consumption is significant, and the injection pump also requires electricity. Dehydration typically uses molecular sieves, and the heat for molecular sieve regeneration requires burning natural gas; process switching also consumes electricity. Summary of the Invention

[0003] To address the aforementioned problems, the inventors have developed this invention, which, through specific embodiments, provides a natural gas wellhead gathering and transportation method and system, as well as a power supply method and apparatus.

[0004] In a first aspect, embodiments of the present invention provide a natural gas wellhead gathering and transportation method, comprising the following steps:

[0005] High-pressure dry gas obtained from the high-pressure well products at the wellhead of the gas well is sent into a differential pressure generator to generate electricity, and low-pressure, low-temperature dry gas is output.

[0006] A portion of the low-pressure, low-temperature dry gas is electrically heated to obtain high-temperature dry gas that reaches the preset temperature.

[0007] High-temperature dry gas is fed into a molecular sieve tower that has absorbed moisture to adsorb the moisture, resulting in high-temperature humid gas; wherein, the electrical energy required for electric heating and the electric valve of the molecular sieve tower is supplied by the differential pressure generator.

[0008] High-temperature humid air and another part of low-pressure low-temperature dry air are fed into a gas-to-gas heat exchanger for heat exchange, resulting in cooled humid air and reheated dry air, respectively.

[0009] Cooled, moist gas is fed into the regeneration gas separator to separate free condensate, resulting in separated regeneration gas.

[0010] The reheated dry gas is mixed with the separated regenerated gas and reheated a second time to obtain a mixed gas that meets the pipeline transportation requirements, and the mixed gas is then transported outward.

[0011] Specifically, obtaining high-pressure dry gas from the high-pressure well products at the gas wellhead includes the following steps:

[0012] High-pressure well products from the gas wellhead are fed into the wellhead separator to separate out high-pressure wet gas.

[0013] High-pressure humid gas is fed into a molecular sieve tower, where the saturated water in the high-pressure humid gas is absorbed to obtain high-pressure dry gas.

[0014] Specifically, the natural gas wellhead gathering and transportation method further includes the following steps:

[0015] When the moisture absorbed by the molecular sieve tower exceeds the preset upper limit threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve regeneration mode, stopping the high-pressure humid gas from being sent into the molecular sieve tower and inputting high-temperature dry gas into the molecular sieve tower.

[0016] When the moisture absorbed by the molecular sieve tower is lower than the preset lower threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve absorption mode, stopping the supply of high-temperature dry gas to the molecular sieve tower and allowing high-pressure humid gas to be input into the molecular sieve tower.

[0017] Specifically, the natural gas wellhead gathering and transportation method further includes the following steps:

[0018] The low-pressure, low-temperature dry gas obtained after the high-pressure dry gas is sent to the differential pressure generator to generate electricity is input into the proportional distributor. The low-pressure, low-temperature dry gas is divided into two parts according to the preset ratio. The larger part is used for heat exchange with the high-temperature humid gas in the input gas heat exchanger, and the smaller part is used for electric heating.

[0019] Specifically, determining the preset ratio includes the following steps:

[0020] The simulation yields the optimal distribution ratio of the regenerated gas after separation when the gas volume, pressure, and water content of the gas well change. Based on the optimal distribution ratio of the regenerated gas after separation, the preset ratio is determined, and the preset ratio is adaptively changed and automatically adjusted through online monitoring.

[0021] Specifically, a portion of the low-pressure, low-temperature dry gas is electrically heated to obtain high-temperature dry gas that reaches a preset temperature, including the following steps:

[0022] The upper limit of the molecular sieve temperature stress is determined, and the upper limit of the electric heating temperature change rate is determined based on the upper limit of the molecular sieve temperature stress. Based on the upper limit of the electric heating temperature change rate, the power of the electric heater is controlled, a portion of low-pressure low-temperature dry gas is input into the electric heater, and high-temperature dry gas reaching the preset temperature is output.

[0023] Specifically, the differential pressure generator is also used for power transmission.

[0024] Secondly, embodiments of the present invention provide a natural gas wellhead gathering and transportation system, comprising:

[0025] The molecular sieve tower is used to switch the molecular sieve tower to molecular sieve regeneration mode by activating an electric valve when the moisture absorbed by the molecular sieve tower exceeds a preset upper threshold, stopping the supply of high-pressure humid gas to the molecular sieve tower and supplying high-temperature dry gas to the molecular sieve tower; when the moisture absorbed by the molecular sieve tower is lower than a preset lower threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve absorption mode, stopping the supply of high-temperature dry gas to the molecular sieve tower and supplying high-pressure humid gas to the molecular sieve tower.

[0026] A differential pressure generator is used to generate electricity from high-pressure dry gas and output low-pressure, low-temperature dry gas. The high-pressure dry gas is obtained through high-pressure well products at the wellhead of a gas well.

[0027] An electric heater is used to electrically heat a portion of low-pressure, low-temperature dry gas to obtain high-temperature dry gas that reaches a preset temperature.

[0028] A gas-to-gas heat exchanger is used to exchange heat between high-temperature humid gas and another part of low-pressure, low-temperature dry gas to obtain cooled humid gas and reheated dry gas, respectively.

[0029] The regeneration gas separator is used to separate free condensate from the cooled humid gas to obtain the separated regeneration gas.

[0030] The mixed gas output module is used to mix reheated dry gas with separated regenerated gas, perform secondary reheating, obtain mixed gas that meets pipeline transportation requirements, and then export the mixed gas.

[0031] Specifically, the natural gas wellhead gathering and transmission system also includes:

[0032] Wellhead separators are used to separate high-pressure wet gas from the high-pressure well products at the wellhead of gas wells;

[0033] Molecular sieve towers are also used to absorb saturated water in high-pressure humid gas to obtain high-pressure dry gas;

[0034] The proportional distributor is used to divide low-pressure, low-temperature dry gas into two parts according to a preset ratio. The larger part is used for heat exchange with the high-temperature humid gas in the input gas heat exchanger, and the smaller part is used for electric heating.

[0035] Thirdly, embodiments of the present invention provide a method for supplying power to a natural gas wellhead, comprising the following steps:

[0036] High-pressure well products from the gas wellhead are fed into the wellhead separator to separate out high-pressure wet gas.

[0037] High-pressure humid gas is fed into a molecular sieve tower, where the molecular sieve tower absorbs the saturated water in the high-pressure humid gas to obtain high-pressure dry gas.

[0038] High-pressure dry gas is sent into a differential pressure generator to generate electricity and supply power to the load.

[0039] Fourthly, embodiments of the present invention provide a natural gas wellhead power supply device, comprising:

[0040] The high-pressure dry gas output module is used to send the high-pressure well products from the gas wellhead into the wellhead separator to separate high-pressure wet gas; the high-pressure wet gas is then sent into a molecular sieve tower, where the molecular sieve tower absorbs the saturated water in the high-pressure wet gas to obtain high-pressure dry gas.

[0041] The power supply module is used to send high-pressure dry gas into the differential pressure generator to generate electricity and supply power to the load.

[0042] Based on the same inventive concept, this invention provides a natural gas wellhead control device, including: a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the aforementioned natural gas wellhead gathering and transportation method or natural gas wellhead power supply method.

[0043] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0044] This invention fully utilizes the formation pressure energy during natural gas gathering and transportation, effectively leveraging the pressure difference to optimize energy consumption and achieve wellhead energy self-sufficiency. Excess electricity can also be exported. It meets the energy consumption requirements for molecular sieve regeneration, natural gas reheating, and system operation in the well site gathering and transportation system. The hydrate formation temperature can be controlled to meet pipeline transportation requirements, avoiding waste of regenerated gas and saving energy for deep dehydration of the regenerated gas. Especially in remote gas wells lacking power and heat system support, this invention can convert formation pressure energy into electrical and thermal energy for the gathering and transportation process. Furthermore, this invention can adapt to changes in wellhead parameters and automatically adjust the regenerated gas ratio, automatically achieving material balance with good adaptability.

[0045] Other features and advantages of the invention will be set forth in the following description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0046] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0047] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0048] Figure 1 This is a flowchart of the natural gas wellhead gathering and transportation method in an embodiment of the present invention;

[0049] Figure 2This is a schematic diagram of the gas wellhead energy utilization method in an embodiment of the present invention;

[0050] Figure 3 This is an adaptive material balance table in an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram of the structure of a natural gas wellhead control device according to an embodiment of the present invention. Detailed Implementation

[0052] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0053] To address the problems existing in the prior art, embodiments of the present invention provide a natural gas wellhead gathering and transportation method and system, a power supply method and apparatus.

[0054] This invention provides a natural gas wellhead gathering and transportation method, the process of which is as follows: Figure 1 As shown, it includes the following steps:

[0055] Step S1: The high-pressure dry gas obtained from the high-pressure well products at the wellhead of the gas well is sent to the differential pressure generator to generate electricity and output low-pressure, low-temperature dry gas.

[0056] In some specific embodiments, high-pressure dry gas is obtained from the high-pressure well products at the gas wellhead, including the following steps: sending the high-pressure well products at the gas wellhead into a wellhead separator to separate high-pressure wet gas; sending the high-pressure wet gas into a molecular sieve tower, where the molecular sieve tower absorbs the saturated water in the high-pressure wet gas to obtain high-pressure dry gas.

[0057] Step S2: A portion of the low-pressure, low-temperature dry gas is electrically heated to obtain high-temperature dry gas that reaches the preset temperature. The high-temperature dry gas is then fed into a molecular sieve tower that has absorbed moisture to adsorb the moisture, resulting in high-temperature humid gas. The electrical energy required for the electric heating and the electric valve of the molecular sieve tower is supplied by the differential pressure generator.

[0058] In some specific embodiments, a portion of the low-pressure, low-temperature dry gas is electrically heated to obtain high-temperature dry gas that reaches a preset temperature, including the following steps:

[0059] The upper limit of the molecular sieve temperature stress is determined, and the upper limit of the electric heating temperature change rate is determined based on the upper limit of the molecular sieve temperature stress. Based on the upper limit of the electric heating temperature change rate, the power of the electric heater is controlled, a portion of low-pressure low-temperature dry gas is input into the electric heater, and high-temperature dry gas reaching the preset temperature is output.

[0060] In some specific embodiments, the natural gas wellhead gathering and transportation method further includes the following steps:

[0061] When the moisture absorbed by the molecular sieve tower exceeds the preset upper limit threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve regeneration mode, stopping the high-pressure humid gas from being sent into the molecular sieve tower and inputting high-temperature dry gas into the molecular sieve tower.

[0062] When the moisture absorbed by the molecular sieve tower is lower than the preset lower threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve absorption mode, stopping the supply of high-temperature dry gas to the molecular sieve tower and allowing high-pressure humid gas to be input into the molecular sieve tower.

[0063] In some specific embodiments, the natural gas wellhead gathering and transportation method further includes the following steps:

[0064] The low-pressure, low-temperature dry gas obtained after the high-pressure dry gas is sent to the differential pressure generator to generate electricity is input into the proportional distributor. The low-pressure, low-temperature dry gas is divided into two parts according to the preset ratio. The larger part is used for heat exchange with the high-temperature humid gas in the input gas heat exchanger, and the smaller part is used for electric heating.

[0065] In some specific embodiments, determining the preset ratio includes the following steps:

[0066] The simulation yields the optimal distribution ratio of the regenerated gas after separation when the gas volume, pressure, and water content of the gas well change. Based on the optimal distribution ratio of the regenerated gas after separation, the preset ratio is determined, and the preset ratio is adaptively changed and automatically adjusted through online monitoring.

[0067] In some specific embodiments, the differential pressure generator is also used for power transmission.

[0068] Step S3: High-temperature humid gas and another portion of low-pressure, low-temperature dry gas are fed into a gas-to-gas heat exchanger for heat exchange, resulting in cooled humid gas and reheated dry gas, respectively. The cooled humid gas is then fed into a regeneration gas separator to separate free condensate, yielding separated regeneration gas. The reheated dry gas is mixed with the separated regeneration gas and subjected to secondary reheating to obtain a mixed gas that meets pipeline transportation requirements. This mixed gas is then exported. The natural gas wellhead gathering and transportation system produced using this method can operate independently without requiring an external power or heat source.

[0069] In some specific embodiments, such as Figure 2 As shown, the natural gas wellhead gathering and transportation method includes the following steps: (1) preliminary separation; (2) molecular sieve dehydration; (3) differential pressure power generation; (4) proportional distribution; (5) electric heating; (6) molecular sieve regeneration; (7) heat exchange reheating; (8) condensate separation; (9) mixing reheating.

[0070] (1) Preliminary separation: The flow material in a gas well is generally a multiphase flow under the temperature and pressure at the wellhead, including gas, oil and water. The gas phase contains light hydrocarbon components, such as methane, ethane and propane, as well as saturated water content under the temperature and pressure at the wellhead. The oil phase contains free condensate oil carried by the gas phase, as well as condensate oil produced by the condensation phenomenon. The water phase is free water carried by the gas phase. The condensate oil will cause certain pollution to the molecular sieve in the downstream section, and the free water will also reduce the effective adsorption water volume of the molecular sieve (generally, the adsorbed saturated water content is taken as the effective adsorption water volume). Therefore, the high-pressure wet gas containing condensate oil and free water should be separated at the front end of the molecular sieve to improve the water absorption efficiency of the molecular sieve absorption tower.

[0071] (2) Molecular sieve dehydration: Since low temperature will be generated after the differential pressure power generation, in order to prevent the low temperature gas from freezing after power generation, molecular sieve dehydration is carried out at the front end of the differential pressure generator. By utilizing the polar hydrophilicity of porous molecular sieve particles, saturated water in the gas phase can be selectively adsorbed, so that the high pressure humid gas in the gas phase becomes high pressure dry gas. The hydrate formation temperature is reduced from 20℃~30℃ to <-90℃, ensuring that the low temperature gas after power generation does not freeze.

[0072] (3) Differential pressure power generation: High-pressure dry gas drives the rotor of the differential pressure generator, which generates electricity by cutting magnetic lines of force. After power generation, the pressure and temperature of the natural gas are reduced, becoming low-pressure (low-temperature) dry gas. By making full use of the formation pressure energy, the energy consumption requirements of molecular sieve regeneration, natural gas reheating and system operation of the well site gathering and transportation system can be met without relying on external energy sources.

[0073] (4) Proportional allocation: Using the database of optimal allocation ratios of regenerated gas when different parameters (gas volume, pressure, water content) of the gas well change, obtained from simulation, the parameters monitored online are compared with the database data, and the corresponding ratio is selected for gas volume adjustment and allocation, so that the regenerated gas volume can adapt to parameter changes and automatically adjust.

[0074] (5) Electric heating: Low-temperature regenerated gas separated from low-pressure (low-temperature) dry gas in proportion enters the electric heater (the electric heater is powered by a differential pressure generator). While heating, it provides dry gas for molecular sieve regeneration downstream. The heating process should be stable and gradually reach the design temperature. The requirement is that the process temperature rise rate should avoid the molecular sieve from breaking due to temperature stress.

[0075] (6) Molecular sieve regeneration: The electrically heated dry gas is gradually heated before entering the molecular sieve regeneration tower, continuously carrying away the moisture adsorbed by the molecular sieve. As the temperature rises to the design temperature, the molecular sieve purged by the regeneration gas gradually regains its water absorption capacity, while the regeneration gas becomes high-temperature humid gas. The molecular sieve absorption tower and the molecular sieve regeneration tower are different states of the same molecular sieve tower. The molecular sieve absorption tower absorbs moisture below the preset lower threshold, while the molecular sieve regeneration tower absorbs moisture above the preset upper threshold.

[0076] (7) Heat exchange and reheating: The high-temperature humid gas from the molecular sieve regeneration tower exchanges heat with a large amount of (low-temperature) dry gas. The temperature of the high-temperature humid gas decreases (condensation will be released during the cooling process) and becomes cooled humid gas. The low-temperature dry gas is reheated and becomes reheated dry gas.

[0077] (8) Condensate separation: The cooled humid gas is in the regeneration gas separator (generally a cyclone separator) where the centrifugal force of rotation throws out the condensate, which becomes the separated regeneration gas.

[0078] (9) Mixing and Reheating: The separated regenerated gas is in a saturated water-containing state (high hydrate formation temperature) and cannot be transported alone (GB50349-2015:4.5.1 stipulates that the hydrate formation point throughout the entire gathering and transportation process is more than 3℃ below the gathering and transportation temperature). It needs to be mixed with reheated dry gas (hydrate formation temperature < -90℃). The hydrate formation temperature of the mixed gas meets the pipeline transportation requirements. Instead of further dehydrating the saturated water-containing separated regenerated gas (high hydrate formation temperature), it is mixed with reheated dry gas (low hydrate formation temperature), so that the mixed gas formation temperature (between high and low) meets the pipeline transportation requirements. Mixing for external transportation not only controls the hydrate formation temperature to meet the pipeline transportation requirements, but also avoids the waste of regenerated gas and saves energy consumption for deep dehydration of regenerated gas. For example, under the external transportation conditions of 14.96MPa and 28.29℃, the hydrate formation temperature of the mixed gas is -3.47℃, which meets the requirement that the hydrate formation point is more than 3℃ below the gathering and transportation temperature.

[0079] Specifically, in the past, gas wellheads were not dehydrated and insulated before transportation, and the transportation distance was generally no more than 35km. With the present invention, the water content of the mixed gas is greatly reduced, so the transportation distance exceeds 100km. In principle, there is no limitation on the transportation distance, and it is only limited by the starting pressure under the condition of fixed pipe diameter.

[0080] For example, with a gas wellhead production of 35×10 4 Nm 3 The wellhead parameters, calculated per day, are 60 MPa and 65℃. The composition table is as follows:

[0081] Serial Number Components mol% 1 <![CDATA[C1]]> 92.40 2 <![CDATA[C2]]> 4.10 3 <![CDATA[C3]]> 0.89 4 <![CDATA[iC4]]> 0.25 5 <![CDATA[nC4]]> 0.21 6 <![CDATA[C5 + ]]> 0.35 7 <![CDATA[CO2]]> 0.58 8 <![CDATA[N2]]> 1.08 9 <![CDATA[H2O]]> 0.14

[0082] The corresponding material balance sheet is as follows: Figure 3 As shown, the regeneration gas volume can adaptively adapt to parameter changes and automatically adjust. The electricity generated by the differential pressure generator supplies power to the electric heater, with a power of 194.2kW, and can also supply power to external systems, with a power of 221.7kW.

[0083] The gathering and transmission system has a pressure of 15MPa and can generate more than 400kW of electricity, which can drive the operation of a molecular sieve dehydration system of about 200kW (of which, 190kW is for regeneration and 10kW is for other uses). In addition, it can output about 200kW of electrical power. Calculated at 0.44 yuan / kWh, the annual power generation value is 1.54 million yuan, that is, the energy utilization value provided by this invention is 1.54 million yuan per year.

[0084] The method described in this embodiment fully utilizes the formation pressure energy during the natural gas gathering and transportation process, effectively leveraging the pressure difference to optimize energy consumption and achieve wellhead energy self-sufficiency. Excess electricity can also be exported. It meets the energy consumption requirements for molecular sieve regeneration, natural gas reheating, and system operation in the well site gathering and transportation system. The hydrate formation temperature can be controlled to meet pipeline transportation requirements, avoiding waste of regenerated gas and saving energy for deep dehydration of the regenerated gas. Especially for gas wells in remote areas lacking power and heat system support, this invention can convert formation pressure energy into electrical and thermal energy for the gathering and transportation process. It eliminates the distance limitations of wet gas transportation. Furthermore, this invention can adapt to changes in wellhead parameters and automatically adjust the regenerated gas ratio, automatically achieving material balance, demonstrating good adaptability.

[0085] Those skilled in the art can change the above order without departing from the scope of protection of this disclosure.

[0086] Another embodiment of the present invention provides a natural gas wellhead gathering and transportation system, comprising:

[0087] The molecular sieve tower is used to switch the molecular sieve tower to molecular sieve regeneration mode by activating an electric valve when the moisture absorbed by the molecular sieve tower exceeds a preset upper threshold, stopping the supply of high-pressure humid gas to the molecular sieve tower and supplying high-temperature dry gas to the molecular sieve tower; when the moisture absorbed by the molecular sieve tower is lower than a preset lower threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve absorption mode, stopping the supply of high-temperature dry gas to the molecular sieve tower and supplying high-pressure humid gas to the molecular sieve tower.

[0088] A differential pressure generator is used to generate electricity from high-pressure dry gas and output low-pressure, low-temperature dry gas. The high-pressure dry gas is obtained through high-pressure well products at the wellhead of a gas well.

[0089] An electric heater is used to electrically heat a portion of low-pressure, low-temperature dry gas to obtain high-temperature dry gas that reaches a preset temperature.

[0090] A gas-to-gas heat exchanger is used to exchange heat between high-temperature humid gas and another part of low-pressure, low-temperature dry gas to obtain cooled humid gas and reheated dry gas, respectively.

[0091] The regeneration gas separator is used to separate free condensate from the cooled humid gas to obtain the separated regeneration gas.

[0092] The mixed gas output module is used to mix reheated dry gas with separated regenerated gas, perform secondary reheating, obtain mixed gas that meets pipeline transportation requirements, and then export the mixed gas.

[0093] Specifically, the natural gas wellhead gathering and transmission system also includes:

[0094] Wellhead separators are used to separate high-pressure wet gas from the high-pressure well products at the wellhead of gas wells;

[0095] Molecular sieve towers are also used to absorb saturated water in high-pressure humid gas to obtain high-pressure dry gas;

[0096] The proportional distributor is used to divide low-pressure, low-temperature dry gas into two parts according to a preset ratio. The larger part is used for heat exchange with the high-temperature humid gas in the input gas heat exchanger, and the smaller part is used for electric heating.

[0097] Regarding the systems in the above embodiments, the specific ways in which each device or module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0098] This embodiment fully utilizes the formation pressure energy during natural gas gathering and transportation, effectively leveraging the pressure difference to optimize energy consumption and achieve wellhead energy self-sufficiency. Excess electricity can also be exported. It meets the energy consumption requirements for molecular sieve regeneration, natural gas reheating, and system operation in the well site gathering and transportation system. The hydrate formation temperature can be controlled to meet pipeline transportation requirements, avoiding waste of regenerated gas and saving energy for deep dehydration of the regenerated gas. Especially in remote gas wells lacking power and heat system support, this invention can convert formation pressure energy into electrical and thermal energy for the gathering and transportation process. Furthermore, this invention can adapt to changes in wellhead parameters and automatically adjust the regenerated gas ratio, automatically achieving material balance, demonstrating good adaptability.

[0099] Thirdly, embodiments of the present invention provide a method for supplying power to a natural gas wellhead, comprising the following steps:

[0100] High-pressure well products from the gas wellhead are fed into the wellhead separator to separate out high-pressure wet gas.

[0101] High-pressure humid gas is fed into a molecular sieve tower, where the molecular sieve tower absorbs the saturated water in the high-pressure humid gas to obtain high-pressure dry gas.

[0102] High-pressure dry gas is sent into a differential pressure generator to generate electricity and supply power to the load.

[0103] For example, with a gas wellhead production of 35×10 4 Nm 3The wellhead parameters are calculated at 60 MPa and 65℃. The differential pressure generator supplies power to the electric heater (194.2 kW) and can supply power to external systems (221.7 kW). The gathering and transmission system operates at 15 MPa and can generate over 400 kW of electricity, enough to power a molecular sieve dewatering system of approximately 200 kW (190 kW for regeneration and 10 kW for other functions). It can also output approximately 200 kW of electrical power. Based on a price of 0.44 yuan / kWh, the annual power generation value is 1.54 million yuan.

[0104] Regarding the natural gas wellhead power supply method in the above embodiments, the specific implementation methods have been described in detail in the foregoing embodiments, and will not be elaborated here.

[0105] In this embodiment, the formation pressure energy during the natural gas gathering and transportation process is fully utilized, the pressure difference during the gathering and transportation process is effectively utilized, the energy consumption of gathering and transportation is optimized, the wellhead energy self-sufficiency is achieved, and the excess electricity can be exported; especially for some gas wells in remote areas that lack power and heat system support, this invention can convert formation pressure energy into electricity and heat energy for the gathering and transportation process.

[0106] Fourthly, embodiments of the present invention provide a natural gas wellhead power supply device, comprising:

[0107] The high-pressure dry gas output module is used to send the high-pressure well products from the gas wellhead into the wellhead separator to separate high-pressure wet gas; the high-pressure wet gas is then sent into a molecular sieve tower, where the molecular sieve tower absorbs the saturated water in the high-pressure wet gas to obtain high-pressure dry gas.

[0108] The power supply module is used to send high-pressure dry gas into the differential pressure generator to generate electricity and supply power to the load.

[0109] Regarding the natural gas wellhead power supply device in the above embodiments, the specific implementation method has been described in detail in the foregoing embodiments, and will not be elaborated here.

[0110] In this embodiment, the formation pressure energy during the natural gas gathering and transportation process is fully utilized, the pressure difference during the gathering and transportation process is effectively utilized, the energy consumption of gathering and transportation is optimized, the wellhead energy self-sufficiency is achieved, and the excess electricity can be exported; especially for some gas wells in remote areas that lack power and heat system support, this invention can convert formation pressure energy into electricity and heat energy for the gathering and transportation process.

[0111] Based on the same inventive concept, embodiments of the present invention provide a natural gas wellhead control device, the structure of which is as follows: Figure 4 As shown, it includes: a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the aforementioned natural gas wellhead gathering and transportation method or natural gas wellhead power supply method.

[0112] Any modifications, additions, and equivalent substitutions made within the scope of the principles of this invention shall still fall within the patent coverage of this invention.

Claims

1. A natural gas wellhead gathering and transportation method, characterized in that, Includes the following steps: High-pressure dry gas obtained from the high-pressure well products at the wellhead of the gas well is sent into a differential pressure generator to generate electricity, and low-pressure, low-temperature dry gas is output. A portion of the low-pressure, low-temperature dry gas is electrically heated to obtain high-temperature dry gas that reaches the preset temperature. High-temperature dry gas is fed into a molecular sieve tower that has absorbed moisture to adsorb the moisture, resulting in high-temperature humid gas; wherein, the electrical energy required for electric heating and the electric valve of the molecular sieve tower is supplied by the differential pressure generator, enabling the natural gas wellhead gathering and transportation method to achieve energy self-sufficiency without relying on external power grids. High-temperature humid air and another part of low-pressure low-temperature dry air are fed into a gas-to-gas heat exchanger for heat exchange, resulting in cooled humid air and reheated dry air, respectively. Cooled, moist gas is fed into the regeneration gas separator to separate free condensate, resulting in separated regeneration gas. The reheated dry gas is mixed with the separated regenerated gas and reheated a second time to obtain a mixed gas that meets the pipeline transportation requirements, and the mixed gas is then transported outwards. The high-pressure dry gas is fed into the differential pressure generator to generate electricity, and the resulting low-pressure low-temperature dry gas is input into the proportional distributor. The low-pressure low-temperature dry gas is divided into two parts according to the preset ratio. The larger part is used for heat exchange with the high-temperature humid gas in the gas-to-gas heat exchanger, and the smaller part is used for electric heating. Determining the preset ratio includes the following steps: simulating the optimal allocation ratio of the regenerated gas after separation when the gas volume, pressure, and water content of the gas well change; determining the preset ratio based on the optimal allocation ratio of the regenerated gas after separation; and automatically adjusting the preset ratio through online monitoring.

2. The method as described in claim 1, characterized in that, Obtaining high-pressure dry gas from high-pressure well products at the wellhead of a gas well includes the following steps: High-pressure well products from the gas wellhead are fed into the wellhead separator to separate out high-pressure wet gas. High-pressure humid gas is fed into a molecular sieve tower, where the saturated water in the high-pressure humid gas is absorbed to obtain high-pressure dry gas.

3. The method as described in claim 2, characterized in that, The natural gas wellhead gathering and transportation method further includes the following steps: When the moisture absorbed by the molecular sieve tower exceeds the preset upper limit threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve regeneration mode, stop sending high-pressure humid gas into the molecular sieve tower, and input high-temperature dry gas into the molecular sieve tower. When the moisture absorbed by the molecular sieve tower is lower than the preset lower threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve absorption mode, stopping the supply of high-temperature dry gas to the molecular sieve tower and allowing high-pressure humid gas to be input into the molecular sieve tower.

4. The method as described in claim 1, characterized in that, A portion of the low-pressure, low-temperature dry gas is electrically heated to obtain high-temperature dry gas that reaches a preset temperature, including the following steps: The upper limit of the molecular sieve temperature stress is determined, and the upper limit of the electric heating temperature change rate is determined based on the upper limit of the molecular sieve temperature stress. Based on the upper limit of the electric heating temperature change rate, the power of the electric heater is controlled, a portion of low-pressure low-temperature dry gas is input into the electric heater, and high-temperature dry gas reaching the preset temperature is output.

5. The method as described in claim 1, characterized in that, The differential pressure generator is also used for power transmission.

6. A natural gas wellhead gathering and transportation system for implementing the method according to any one of claims 1-5, characterized in that, include: The molecular sieve tower is used to switch the molecular sieve tower to molecular sieve regeneration mode by activating an electric valve when the moisture absorbed by the molecular sieve tower exceeds a preset upper threshold, stopping the supply of high-pressure humid gas to the molecular sieve tower and supplying high-temperature dry gas to the molecular sieve tower; when the moisture absorbed by the molecular sieve tower is lower than a preset lower threshold, the electric valve is activated to switch the molecular sieve tower to molecular sieve absorption mode, stopping the supply of high-temperature dry gas to the molecular sieve tower and supplying high-pressure humid gas to the molecular sieve tower. A differential pressure generator is used to generate electricity from high-pressure dry gas and output low-pressure, low-temperature dry gas. The high-pressure dry gas is obtained through high-pressure well products at the wellhead of a gas well. An electric heater is used to electrically heat a portion of low-pressure, low-temperature dry gas to obtain high-temperature dry gas that reaches a preset temperature. A gas-to-gas heat exchanger is used to exchange heat between high-temperature humid gas and another part of low-pressure, low-temperature dry gas to obtain cooled humid gas and reheated dry gas, respectively. The regeneration gas separator is used to separate free condensate from the cooled humid gas to obtain the separated regeneration gas. The mixed gas output module is used to mix reheated dry gas with separated regenerated gas, perform secondary reheating, obtain mixed gas that meets pipeline transportation requirements, and then export the mixed gas.

7. The system as described in claim 6, characterized in that, The natural gas wellhead gathering and transmission system also includes: Wellhead separators are used to separate high-pressure wet gas from the high-pressure well products at the wellhead of gas wells; Molecular sieve towers are also used to absorb saturated water in high-pressure humid gas to obtain high-pressure dry gas; The proportional distributor is used to divide low-pressure, low-temperature dry gas into two parts according to a preset ratio. The larger part is used for heat exchange with the high-temperature humid gas in the input gas heat exchanger, and the smaller part is used for electric heating.

8. A method for supplying power to a natural gas wellhead, applied to the system described in claim 6 or 7, characterized in that, Includes the following steps: High-pressure well products from the gas wellhead are fed into the wellhead separator to separate out high-pressure wet gas. High-pressure humid gas is fed into a molecular sieve tower, where the molecular sieve tower absorbs the saturated water in the high-pressure humid gas to obtain high-pressure dry gas. High-pressure dry gas is sent into a differential pressure generator to generate electricity and supply power to the load.

9. A natural gas wellhead power supply device, applied to the system described in claim 6 or 7, characterized in that, include: The high-pressure dry gas output module is used to send the high-pressure well products from the gas wellhead into the wellhead separator to separate out the high-pressure wet gas. High-pressure humid gas is fed into a molecular sieve tower, where the molecular sieve tower absorbs the saturated water in the high-pressure humid gas to obtain high-pressure dry gas. The power supply module is used to send high-pressure dry gas into the differential pressure generator to generate electricity and supply power to the load.

10. A natural gas wellhead control device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor, when executing the computer program, implements the natural gas wellhead gathering and transportation method according to any one of claims 1 to 5 or the natural gas wellhead power supply method according to claim 8.

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