Superheated steam generation system based on molten salt heating, and control method therefor

Abstract

The embodiments of the present invention belong to the technical field of oilfield exploitation. Provided are a superheated steam generation system based on molten salt heating, and a control method therefor. The method comprises: on the basis of steam injection demand information, respectively executing the simulation of target operation states of a water supply apparatus, an evaporation apparatus and a superheated steam generation apparatus, wherein the steam injection demand information is predicted by means of a corresponding LSTM model constructed on the basis of historical steam injection data, a real-time steam demand and an oil well operation parameter; on the basis of deviation values between real-time operation states and corresponding target operation states of the water supply apparatus, the evaporation apparatus and the superheated steam generation apparatus, respectively generating control schemes for the water supply apparatus, the evaporation apparatus and the superheated steam generation apparatus; and executing the control schemes to respectively adjust the states of the water supply apparatus, the evaporation apparatus and the superheated steam generation apparatus. The solution of the present invention effectively solves the problem in the prior art of insufficient response to dynamic steam injection demands, thereby significantly improving the adaptability and operation efficiency of the system, and meeting the requirements for heavy oil exploitation under complex working conditions.

Description

Molten Salt Heated Superheated Steam Generation System and Its Control Method

[0001] Cross-references to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411955276.5, filed on December 27, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of oilfield development technology, specifically to a molten salt heating superheated steam generation system and a control method for the molten salt heating superheated steam generation system. Background Technology

[0004] In the current heavy oil extraction process in oilfields, steam injection technology is one of the key links in enhancing crude oil recovery. Steam injection systems typically require high-temperature, high-pressure superheated steam to meet the needs of oil wells. However, traditional steam injection systems mainly rely on gas-fired boilers to generate steam, which not only leads to high energy consumption and large carbon emissions, but also limits the widespread application of the system under the "dual carbon" target.

[0005] To address these issues, existing technologies have gradually explored molten salt heating technology, using molten salt as a heat storage and transfer medium and off-peak electricity or green electricity as the primary energy source to produce superheated steam. However, existing molten salt steam injection schemes have shortcomings in the following key technological aspects:

[0006] The existing system lacks dynamic adaptability to steam injection demand: it typically operates under fixed conditions and lacks the ability to respond in real time to the dynamic demands (changes in flow rate, temperature, and pressure) of the steam injection well. As the production stage of the oil well changes, the steam injection demand exhibits nonlinear and dynamic fluctuations, while fixed-parameter operation mode can easily lead to steam waste or insufficient supply, reducing steam injection efficiency.

[0007] Insufficient precision in mixer control: During the mixing process of superheated steam and saturated water, existing technologies lack high-precision, real-time control schemes, making it impossible to ensure that the temperature and flow rate of the mixed steam consistently meet the injection requirements. This insufficient control may lead to unstable superheat or flow rate deviations in the mixed steam, directly affecting downhole oil production efficiency.

[0008] In summary, existing technologies cannot effectively cope with the dynamic changes in steam injection demand, and the accuracy of the mixing process also faces technical bottlenecks. There is an urgent need for a dynamic control method that can adapt to changes in steam injection demand in real time, optimize the operating parameters of the mixer, and ensure the stability of the mixed steam and the efficiency of steam injection. Summary of the Invention

[0009] The purpose of this invention is to provide a molten salt heating superheated steam generation system and its control method, so as to at least solve the problems that the prior art cannot effectively cope with the dynamic changes in steam injection demand and the lack of precision in the blending process.

[0010] To achieve the above objectives, the first aspect of the present invention provides a control method for a molten salt heated superheated steam generation system. The method is applied to a molten salt heated superheated steam generation system, which includes a water supply device, an evaporation device, and a superheated steam generation device connected in sequence; a molten salt heating module for supplying heat to the evaporation device and the superheated steam generation device; and a control device for controlling the operating states of the water supply device, the evaporation device, and the superheated steam generation device based on steam injection demand. The method includes: obtaining real-time steam injection demand information, and performing target operating state simulations of the water supply device, the evaporation device, and the superheated steam generation device based on the steam injection demand information; wherein the steam injection demand information is obtained by constructing a corresponding LSTM model prediction based on historical steam injection data, real-time steam demand, and oil well operating parameters; generating control schemes for the water supply device, the evaporation device, and the superheated steam generation device based on the deviation values ​​between the real-time operating states of the water supply device, the evaporation device, and the superheated steam generation device and the corresponding target operating states; and executing the control schemes to achieve state adjustments for the water supply device, the evaporation device, and the superheated steam generation device.

[0011] Optionally, the water supply device includes: a water supply pipe for inputting water as low-temperature water for the water supply device; a preheating module connected to the water supply pipe for preheating the low-temperature water; the preheating module is connected to the evaporation device through a pipe for transmitting the preheated low-temperature water to the evaporation device.

[0012] Optionally, the preheating module includes: a wet saturated steam preheating module, a solar preheating module, and a geothermal energy preheating module, combined to perform preheating of the low-temperature supplied water; the wet saturated steam in the wet saturated steam preheating module is obtained by separating the wet saturated steam output from the evaporator and is fed into the wet saturated steam preheating module via an extraction steam pipeline; another portion of the wet saturated steam output from the evaporator is based on...

[0013] The second wet steam pipeline converges into the steam-water separator; the solar preheating module includes a concentrating solar collector, installed between the wet saturated steam preheating module and the water supply pipeline, used for the first stage of preheating of the low-temperature water supply; the geothermal preheating module includes a geothermal heat exchanger, installed in parallel with the concentrating solar collector, used in combination with the concentrating solar collector to perform the first stage of preheating of the low-temperature water supply; the geothermal heat exchanger is equipped with a three-way valve; the inlet of the three-way valve is used to receive the heating medium of the geothermal heat exchanger; the outlet of the three-way valve is connected to the wet saturated steam preheating module and the molten salt heating module respectively; the opening and closing degree of the three-way valve connected to the wet saturated steam preheating module and the molten salt heating module is controlled by a control device.

[0014] Optionally, the generation rule for the control scheme of the preheating module is as follows: based on historical steam injection data, real-time steam demand, and oil well operating parameters, a corresponding LSTM model is constructed to predict the steam injection demand at a predetermined time in the future; based on the steam injection demand and the heat exchange efficiency of the evaporator, the preheating demand for low-temperature water supply is determined; based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module, the supplementary heat exchange power of the geothermal energy preheating module for performing low-temperature water supply preheating is determined; based on the supplementary heat exchange power of the geothermal energy preheating module, a control scheme for the valve opening degree of the three-way valve to the preheating module is generated, and based on the remaining heat exchange power of the geothermal energy preheating module, a control scheme for the valve opening degree of the three-way valve to the molten salt heating module is generated, which serves as the control scheme for the preheating module.

[0015] Optionally, based on the deviation between the real-time operating status of the water supply device, evaporation device, and superheated steam generator and the corresponding target operating status, control schemes are generated for the water supply device, evaporation device, and superheated steam generator, respectively. These schemes include: constructing corresponding LSTM models based on historical steam injection data, real-time steam demand, and oil well operating parameters to predict future steam injection demand at predetermined times; determining the preheating demand for low-temperature water supply based on the steam injection demand and the heat exchange efficiency of the evaporation device; determining the supplementary heat exchange power of the geothermal energy preheating module for performing low-temperature water supply preheating based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module; generating a control scheme for the valve opening degree of the three-way valve leading to the preheating module based on the supplementary heat exchange power of the geothermal energy preheating module; and generating a control scheme for the valve opening degree of the three-way valve leading to the molten salt heating module based on the remaining heat exchange power of the geothermal energy preheating module.

[0016] Optionally, determining the supplementary heat exchange power of the geothermal preheating module performing low-temperature water supply preheating based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module includes: constructing a corresponding objective function based on a collaborative game theory algorithm, treating the preheating module and the molten salt heating module as game players, to maximize the steam injection demand satisfaction rate and molten salt thermal storage efficiency; and iteratively solving the objective function based on the Lagrange relaxation method to obtain the optimal supplementary heat exchange power of the geothermal preheating module performing low-temperature water supply preheating.

[0017] Optionally, the objective function is expressed as:

[0018] Wherein, ω1 and ω2 represent the preset weighting factors for the importance of produced water preheating requirements and molten salt thermal storage requirements, respectively; Q 地热采 The geothermal heat supply allocated for preheating produced water; Q 采 Total preheating requirements for produced water; Q 地热盐 Q is the geothermal heat supplied for molten salt heating; 盐目标 The target requirement for heating molten salt.

[0019] Optionally, the evaporation device includes multiple heat exchangers; each heat exchanger is connected in series via a pipe, the inlet and outlet of the first heat exchanger are connected, and the outlet of the last heat exchanger is the outlet of the wet saturated steam; the molten salt flow pipe flows from the last heat exchanger to the first heat exchanger and then flows back from the first heat exchanger to the molten salt heating module.

[0020] Optionally, the superheated steam generating device includes: a steam-water separator for separating the incoming wet saturated steam into dry steam and saturated water respectively; the dry steam and saturated water output from the steam-water separator are connected to a superheater and a mixer respectively through a dry steam pipeline and a separated water pipeline; the superheater exchanges heat with a first hot salt pipeline to convert the dry steam into superheated steam.

[0021] Optionally, the superheater is connected to another inlet of the mixer via a first superheated steam pipeline to collect superheated steam into the mixer; the mixer is used to perform superheated steam and saturated water mixing based on the gas injection requirements to obtain superheated steam that meets the gas injection requirements, and outputs the superheated steam to the steam injection well via a second superheated steam pipeline.

[0022] Optionally, the control device is configured to: construct a corresponding heat balance model and flow balance model based on the state information of the superheated steam and saturated water entering the mixer; determine the mixing ratio of superheated steam and saturated water based on the heat balance model and flow balance model; and adjust the valve opening of the mixer in real time according to the mixing ratio.

[0023] Optionally, the heat balance model is expressed as: m混合 *h 混合 =m 过热 *h 饱和 +m 饱和 *h 饱和

[0024] The flow balance model is expressed as: m 混合 =m 过热 +m 饱和

[0025] Where, m 混合 m 过热 and m 饱和 These are the mass flow rates of the mixed steam, superheated steam, and saturated water, respectively; h 混合 h 过热 and h 饱和 These are the specific enthalpy of mixed steam, the specific enthalpy of superheated steam, and the specific enthalpy of saturated water, respectively.

[0026] Optionally, the mixing ratio of superheated steam and saturated water is determined based on the heat balance model and the flow balance model, including: performing a joint solution based on the heat balance model and the flow balance model to obtain the flow ratio of superheated steam and saturated water, so as to determine the mixing ratio of superheated steam and saturated water.

[0027] Optionally, after adjusting the valve opening of the mixer in real time according to the mixing ratio, the control device is further configured to: collect the state parameters of the superheated steam required for steam injection in real time, and identify the deviation value between the superheated steam and the state parameters of the target superheated steam; and execute a PID control algorithm based on the deviation value to correct the valve opening of the mixing device, so as to keep the deviation value between the actual superheated steam state parameters and the target superheated steam state parameters within a preset difference threshold range.

[0028] A second aspect of the present invention provides a molten salt heating superheated steam generation system, the system being used to execute the control method of the molten salt heating superheated steam generation system described above, the system comprising: a water supply device, an evaporation device, and a superheated steam generation device connected in sequence; a molten salt flow pipe provided from the superheated steam generation device to the evaporation device for providing a heat source to the superheated steam generation device and the evaporation device; the water supply device being used to preheat low-temperature input water and transmit the preheated low-temperature input water to the evaporation device, so that the evaporation device converts the preheated low-temperature input water into wet saturated steam; the superheated steam generation device being used to convert the wet saturated steam into superheated steam for steam injection requirements; and a control device being used to control the operating status of the water supply device, the evaporation device, and the superheated steam generation device based on steam injection requirements.

[0029] Optionally, the water supply device includes: a water supply pipeline for inputting oilfield produced water as low-temperature water for the water supply device; a preheating module connected to the water supply pipeline for preheating the low-temperature water; the preheating module is connected to an evaporation device via a pipeline for transmitting the preheated low-temperature water to the evaporation device.

[0030] Optionally, the preheating module includes: a wet saturated steam preheating module, a solar preheating module, and a geothermal energy preheating module, which are combined to perform preheating of the low-temperature supplied water; the wet saturated steam of the wet saturated steam preheating module is obtained by separating the wet saturated steam output from the evaporator and flows into the wet saturated steam preheating module through the extraction steam pipeline; another part of the wet saturated steam output from the evaporator flows into the steam-water separator through the second wet steam pipeline.

[0031] Optionally, the solar preheating module includes: a concentrating solar collector, disposed between the wet saturated steam preheating module and the water supply pipe, for performing the first stage of preheating on the low-temperature water supply; the geothermal preheating module includes: a geothermal heat exchanger, disposed in parallel with the concentrating solar collector, and combined with the concentrating solar collector to perform the first stage of preheating on the low-temperature water supply.

[0032] Optionally, the geothermal heat exchanger is equipped with a three-way valve; the inlet of the three-way valve is used to receive the heating medium of the geothermal heat exchanger; the outlet of the three-way valve is respectively connected to the wet saturated steam preheating module and the molten salt heating module; the opening and closing degree of the three-way valve connected to the wet saturated steam preheating module and the molten salt heating module is controlled by a control device.

[0033] On the other hand, the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described control method for a molten salt heating superheated steam generation system.

[0034] Through the above technical solution, this invention introduces an LSTM model to predict steam injection demand in real time, accurately capturing the dynamic changes in steam injection flow rate, temperature, and pressure in oil wells, thus improving the system's adaptability to complex operating conditions. By analyzing the deviation between the simulated target operating state and the real-time state, closed-loop control of the water supply, evaporation, and superheated steam generation devices is achieved, ensuring that the steam production process always efficiently matches actual demand. This method effectively overcomes the problems of lag and large fluctuations in steam supply in traditional fixed-condition modes, significantly improving the temperature and flow stability of mixed steam, reducing steam waste and energy consumption, ensuring efficient and stable steam injection operation, and enhancing the system's intelligence level and oil well recovery rate.

[0035] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0036] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0037] Figure 1 is a system structure diagram of a molten salt heating superheated steam generation system provided in one embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of the evaporation device provided in one embodiment of the present invention;

[0039] Figure 3 is a schematic diagram of the specific structure of a molten salt heating superheated steam generation system provided in one embodiment of the present invention;

[0040] Figure 4 is a flowchart of the steps of a control method for a molten salt heating superheated steam generation system provided in one embodiment of the present invention.

[0041] Explanation of reference numerals in the attached diagram: 1-Preheating water pipe; 2-Evaporator; 3-Steam extraction pipe; 4-First wet steam pipe; 5-Second wet steam pipe; 6-Second hot brine pipe; 7-Steam-water separator; 8-Separated water pipe; 9-Dry steam pipe; 10-Superheater; 11-First superheated steam pipe; 12-Mixer; 13-Second superheated steam pipe; 14-First hot brine pipe; 15-Cold brine pipe; 16-Preheater; 17-Oilfield produced water supply pipe; 18-Condensate pipe. Detailed Implementation

[0042] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0043] To achieve the above objectives, a first aspect of the present invention provides a molten salt heating superheated steam generation system, the system comprising: a water supply device, an evaporation device, and a superheated steam generation device connected in sequence; a molten salt flow pipe provided from the superheated steam generation device to the evaporation device for providing a heat source to the superheated steam generation device and the evaporation device; the water supply device for preheating low-temperature input water and transmitting the preheated low-temperature input water to the evaporation device, so that the evaporation device converts the preheated low-temperature input water into wet saturated steam; the superheated steam generation device for converting the wet saturated steam into superheated steam for steam injection requirements; and a control device for controlling the operating status of the water supply device, the evaporation device, and the superheated steam generation device based on steam injection requirements.

[0044] Optionally, the water supply device includes: an oilfield produced water supply pipeline for inputting oilfield produced water as low-temperature supply water for the water supply device; a preheating module connected to the oilfield produced water supply pipeline for preheating the low-temperature supply water; the preheating module is connected to an evaporation device via a pipeline for transmitting the preheated low-temperature supply water to the evaporation device.

[0045] Optionally, the preheating module includes: a wet saturated steam preheating module, a solar preheating module, and a geothermal energy preheating module, which are combined to perform preheating of the low-temperature supplied water; the wet saturated steam of the wet saturated steam preheating module is obtained by separating the wet saturated steam output from the evaporator and flows into the wet saturated steam preheating module through a first wet steam pipeline; another part of the wet saturated steam output from the evaporator flows into the evaporator through a second wet steam pipeline.

[0046] Optionally, the solar preheating module includes: a concentrating solar collector, which is installed between the wet saturated steam preheating module and the oilfield produced water supply pipeline, for performing the first stage of preheating on the low-temperature supply water; the geothermal preheating module includes: a geothermal heat exchanger, which is installed in parallel with the concentrating solar collector, and is combined with the concentrating solar collector to perform the first stage of preheating on the low-temperature supply water.

[0047] Optionally, the geothermal heat exchanger is equipped with a three-way valve; the inlet of the three-way valve is used to receive the heating medium of the geothermal heat exchanger; the outlet of the three-way valve is connected to the preheating module and the molten salt heating module respectively; the opening and closing degree of the three-way valve connected to the preheating module and the molten salt heating module is controlled by the control module.

[0048] Optionally, the control module is configured to: construct a corresponding LSTM model based on historical steam injection data, real-time steam demand, and oil well operating parameters to predict future steam injection demand at a predetermined time; determine the preheating demand for low-temperature water supply based on the steam injection demand and the heat exchange efficiency of the evaporator; determine the supplementary heat exchange power of the geothermal energy preheating module for performing low-temperature water supply preheating based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module; generate a control scheme for the valve opening degree of the three-way valve to the preheating module based on the supplementary heat exchange power of the geothermal energy preheating module, and generate a control scheme for the valve opening degree of the three-way valve to the molten salt heating module based on the remaining heat exchange power of the geothermal energy preheating module.

[0049] Optionally, determining the supplementary heat exchange power of the geothermal preheating module performing low-temperature water supply preheating based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module includes: constructing a corresponding objective function based on a collaborative game theory algorithm, treating the preheating module and the molten salt heating module as game players, to maximize the steam injection demand satisfaction rate and molten salt thermal storage efficiency; and iteratively solving the objective function based on the Lagrange relaxation method to obtain the optimal supplementary heat exchange power of the geothermal preheating module performing low-temperature water supply preheating.

[0050] Optionally, the objective function is expressed as:

[0051] Wherein, ω1 and ω2 represent the preset weighting factors for the importance of produced water preheating requirements and molten salt thermal storage requirements, respectively; Q 地热采 The geothermal heat supply allocated for preheating produced water; Q 采 Total preheating requirements for produced water; Q 地热盐 Q is the geothermal heat supplied for molten salt heating; 盐目标 The target requirement for heating molten salt.

[0052] Optionally, the evaporation device includes multiple heat exchangers; each heat exchanger is connected in series via pipes, with the water inlet of the first heat exchanger connected to the water outlet of the water supply device, and the water outlet of the last heat exchanger being the output port of the wet saturated steam; the molten salt flow pipe flows from the last heat exchanger to the first heat exchanger, and then flows back from the first heat exchanger to the molten salt heating module.

[0053] Optionally, the superheated steam generating device includes: a steam-water separator for separating the incoming wet saturated steam into dry steam and saturated water; the dry steam and saturated water output from the steam-water separator are connected to the superheater and the mixer through the dry steam pipeline and the separated water pipeline, respectively; the superheater performs heat exchange with the molten salt flow pipeline to convert the dry steam into superheated steam.

[0054] Optionally, the superheater is connected to another inlet of the mixer via a first superheated steam pipeline to collect superheated steam into the mixer; the mixer is used to perform superheated steam and saturated water mixing based on the gas injection requirements to obtain superheated steam that meets the gas injection requirements, and outputs the superheated steam to the steam injection well via a second superheated steam pipeline.

[0055] Optionally, the control module is configured to: construct corresponding heat balance models and flow balance models based on the state information of superheated steam and saturated water entering the mixer; determine the mixing ratio of superheated steam and saturated water based on the heat balance models and flow balance models; and adjust the valve opening of the mixer in real time according to the mixing ratio.

[0056] Optionally, the heat balance model is expressed as: m混合 *h 混合 =m 过热 *h 饱和 +m 饱和 *h 饱和

[0057] The flow balance model is expressed as: m 混合 =m 过热 +m 饱和

[0058] Where, m 混合 m 过热 and m 饱和 These are the mass flow rates of the mixed steam, superheated steam, and saturated water, respectively; h 混合 h 过热 and h 饱和 These are the specific enthalpy of mixed steam, the specific enthalpy of superheated steam, and the specific enthalpy of saturated water, respectively.

[0059] Optionally, the mixing ratio of superheated steam and saturated water is determined based on the heat balance model and the flow balance model, including: performing a joint solution based on the heat balance model and the flow balance model to obtain the flow ratio of superheated steam and saturated water, so as to determine the mixing ratio of superheated steam and saturated water.

[0060] Optionally, after adjusting the valve opening of the mixer in real time according to the mixing ratio, the control device is further configured to: collect the state parameters of the superheated steam required for steam injection in real time, and identify the deviation value between the superheated steam and the state parameters of the target superheated steam; and execute a PID control algorithm based on the deviation value to correct the valve opening of the mixing device, so as to keep the deviation value between the actual superheated steam state parameters and the target superheated steam state parameters within a preset difference threshold range.

[0061] A second aspect of the present invention provides a control method for a molten salt-heated superheated steam generation system, the method being applied to the molten salt-heated superheated steam generation system according to any one of claims 1-15, the method comprising: collecting real-time steam injection demand information, and performing target operating state simulations of a water supply device, an evaporation device, and a superheated steam generation device based on the steam injection demand information; generating control schemes for the water supply device, the evaporation device, and the superheated steam generation device based on the deviation values ​​between the real-time operating states of the water supply device, the evaporation device, and the superheated steam generation device and the corresponding target operating states; and executing the control schemes to respectively realize state adjustments of the water supply device, the evaporation device, and the superheated steam generation device.

[0062] Optionally, the water supply device includes: an oilfield produced water supply pipeline for inputting oilfield produced water as low-temperature supply water for the water supply device; a preheating module connected to the oilfield produced water supply pipeline for preheating the low-temperature supply water; the preheating module is connected to an evaporation device via a pipeline for transmitting the preheated low-temperature supply water to the evaporation device.

[0063] Optionally, the preheating module includes: a wet saturated steam preheating module, a solar preheating module, and a geothermal preheating module, combined for preheating the low-temperature supplied water; the wet saturated steam in the wet saturated steam preheating module is obtained by separating the wet saturated steam output from the evaporator and flows into the wet saturated steam preheating module via a first wet steam pipeline; another portion of the wet saturated steam output from the evaporator flows into the evaporator via a second wet steam pipeline; the solar preheating module includes: a concentrating solar collector, installed between the wet saturated steam preheating module and the oilfield produced water. Between the water supply pipes, a first-stage preheating is performed on the low-temperature supply water; the geothermal energy preheating module includes: a geothermal heat exchanger, arranged in parallel with the concentrating solar collector, which, in combination with the concentrating solar collector, performs the first-stage preheating on the low-temperature supply water; the geothermal heat exchanger is equipped with a three-way valve; the inlet of the three-way valve is used to receive the heating medium of the geothermal heat exchanger; the outlet of the three-way valve is respectively connected to the preheating module and the molten salt heating module; the opening and closing degree of the three-way valve connected to the preheating module and the molten salt heating module is controlled by the control module.

[0064] Optionally, the generation rule for the control scheme of the preheating module is as follows: based on historical steam injection data, real-time steam demand, and oil well operating parameters, a corresponding LSTM model is constructed to predict the steam injection demand at a predetermined time in the future; based on the steam injection demand and the heat exchange efficiency of the evaporator, the preheating demand for low-temperature water supply is determined; based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module, the supplementary heat exchange power of the geothermal energy preheating module for performing low-temperature water supply preheating is determined; based on the supplementary heat exchange power of the geothermal energy preheating module, a control scheme for the valve opening degree of the three-way valve to the preheating module is generated, and based on the remaining heat exchange power of the geothermal energy preheating module, a control scheme for the valve opening degree of the three-way valve to the molten salt heating module is generated, which serves as the control scheme for the preheating module.

[0065] Figure 1 is a system structure diagram of a molten salt heated superheated steam generation system provided in one embodiment of the present invention. As shown in Figure 1, the embodiment of the present invention provides a molten salt heated superheated steam generation system, the system comprising: a water supply device, an evaporation device, and a superheated steam generation device connected in sequence; a molten salt flow pipe 19 is provided from the superheated steam generation device to the evaporation device for providing a heat source to the superheated steam generation device and the evaporation device; the water supply device is used to preheat the low-temperature input water and transmit the preheated low-temperature input water to the evaporation device, so that the evaporation device converts the preheated low-temperature input water into wet saturated steam; the superheated steam generation device is used to convert the wet saturated steam into superheated steam for steam injection requirements; and a control device is used to control the operating status of the water supply device, the evaporation device, and the superheated steam generation device based on steam injection requirements.

[0066] Preferably, the water supply device includes: a water supply pipeline for inputting oilfield produced water as low-temperature water for the water supply device; a preheating module connected to the water supply pipeline for preheating the low-temperature water; and the preheating module connected to an evaporation device via a pipeline for transmitting the preheated low-temperature water to the evaporation device.

[0067] In this embodiment of the invention, the water supply pipeline, as one of the core components of the water supply device, is used to stably input oilfield produced water into the system, providing a sufficient water source for steam production. Since oilfield produced water typically has a low initial temperature and high silicon content, directly using it in the evaporation process can easily cause scaling in the heat exchanger and reduce system efficiency; therefore, preliminary pretreatment is required.

[0068] The preheating module is connected to the water supply pipeline and employs high-efficiency heat exchange technology to preheat the low-temperature supply water. During the preheating process, multiple heat sources, such as the waste heat from the molten salt system and the extraction heat from wet saturated steam, can be utilized to raise the supply water temperature from the initial 40-70℃ to 230-250℃, effectively reducing the heat load on the evaporator and minimizing the risk of scaling within the evaporator. The preheated low-temperature supply water is then transported to the evaporator through pipelines, further improving the thermal efficiency of the evaporation process and the system stability.

[0069] Based on the present invention, the efficient preheating and stable delivery of oilfield produced water solves the problems of scaling and low thermal efficiency in evaporators caused by poor water quality and large temperature differences in traditional systems. Furthermore, by optimizing the matching of water supply temperature and evaporation conditions, the overall energy utilization rate of the system is significantly improved. In addition, the introduction of the preheating module makes it possible to integrate multiple heat sources into the system, such as utilizing external heat sources like solar and geothermal energy to further improve preheating efficiency, creating conditions for the application of green energy. Overall, this water supply device provides ideal water supply conditions for the subsequent evaporation unit and superheated steam generator, ensuring the efficient and stable operation of the system and meeting dynamic steam injection requirements.

[0070] Preferably, as shown in Figure 2, the preheating module includes: a wet saturated steam preheating module 1601, a solar preheating module 1602, and a geothermal energy preheating module 1603, which are combined to perform preheating of the low-temperature supplied water; the wet saturated steam of the wet saturated steam preheating module 1601 is obtained by separating the wet saturated steam output from the evaporator and flows into the wet saturated steam preheating module 1601 through the extraction steam pipeline; another part of the wet saturated steam output from the evaporator flows into the steam-water separator through the second wet steam pipeline.

[0071] In this embodiment of the invention, the preheating module consists of a wet saturated steam preheating module 1601, a solar preheating module 1602, and a geothermal energy preheating module 1603. These three modules work synergistically to efficiently preheat the low-temperature supplied water. This modular preheating structure not only improves the system's thermal energy utilization rate but also provides technical support for the flexible integration of multiple heat sources.

[0072] The wet saturated steam preheating module 1601 achieves efficient heat recovery by utilizing the wet saturated steam output from the evaporator. After separation, a portion of the wet saturated steam flows into the wet saturated steam preheating module 1601 through the first wet steam pipeline to preheat the low-temperature supplied water. This method not only recovers the sensible and latent heat of the wet saturated steam but also avoids heat waste caused by direct discharge, while reducing the overall energy consumption of the evaporator. The other portion of the wet saturated steam is returned to the evaporator through the second wet steam pipeline to regulate the stability of the evaporator and further optimize heat distribution.

[0073] The solar preheating module 1602, as one of the ways to utilize clean energy, converts collected solar heat into a heat source for supplying low-temperature water through a high-efficiency solar collector. This module not only reduces dependence on traditional energy sources but also utilizes the difference in grid load between day and night, enabling the system to operate in conjunction with green electricity and improving energy efficiency.

[0074] The geothermal preheating module 1603 extracts geothermal resources through a geothermal heat exchanger to preheat the low-temperature feed water. This design, utilizing low-temperature geothermal resources, fully leverages the advantages of geothermal resources in primary heat energy replenishment, reduces the load on the molten salt system during the preheating stage, and provides stable water supply conditions for subsequent evaporation units. Furthermore, drilling is an essential operation in heavy oil steam injection development, and geothermal resource development also requires drilling. Combining steam injection drilling with geothermal development drilling allows for the sharing of drilling resources, reducing overall construction costs. This integrated utilization avoids the waste caused by repeated drilling and fully utilizes the value of drilling equipment. Oilfield blocks are typically located in geologically active areas, which are often accompanied by abundant geothermal resources. Steam injection development itself requires deep drilling, through which geothermal fluids (such as geothermal hot water or geothermal steam) can be directly obtained. This natural geothermal resource acquisition method provides a low-cost, stable heat source for the preheating and heating processes of the steam injection system.

[0075] Preferably, the solar preheating module 1602 includes: a concentrating solar collector, disposed between the wet saturated steam preheating module 1601 and the water supply pipe, for performing the first stage of preheating on the low-temperature water supply; the geothermal preheating module 1603 includes: a geothermal heat exchanger, disposed in parallel with the concentrating solar collector, and combined with the concentrating solar collector to perform the first stage of preheating on the low-temperature water supply.

[0076] In this embodiment of the invention, the solar preheating module includes a concentrating solar collector, mainly installed between the wet saturated steam preheating module 1601 and the water supply pipeline, for performing the first stage of preheating of the low-temperature supply water. The concentrating solar collector captures solar heat and converts it into thermal energy through efficient light concentration and heat absorption technology, providing an initial temperature increase for the supply water. The collector can automatically adjust the concentration angle according to the intensity of sunlight to maximize heat collection efficiency, raising the initial temperature of the supply water from ambient temperature to 50-90°C, thus reducing the heat load on the subsequent wet saturated steam preheating module 1601. Furthermore, this module can combine daytime and nighttime grid load fluctuations, operating in conjunction with off-peak electricity and green electricity to provide stable, low-cost clean energy preheating for the water supply system.

[0077] Furthermore, the geothermal preheating module 1603 includes a geothermal heat exchanger, arranged in parallel with a concentrating solar collector, to complete the first-stage preheating of the low-temperature water supply. The geothermal heat exchanger, directly connected to a geothermal well, transfers heat from the geothermal fluid to the water supply through a high-efficiency heat exchanger. This module fully utilizes the stable heat supply capacity of geothermal resources, unaffected by weather or time, providing reliable heat input for the low-temperature water supply. During the preheating process, the geothermal heat exchanger and the solar collector operate collaboratively, each undertaking the primary preheating task at different times. For example, during the day, solar energy is the primary source, with geothermal energy serving as an auxiliary heat source; at night and on cloudy days, geothermal energy provides all the heat, ensuring the continuity and stability of the entire water supply system.

[0078] Furthermore, by arranging concentrating solar collectors and geothermal heat exchangers side-by-side and combining them to complete the first stage of preheating, this solution achieves efficient synergy of multiple heat sources. The combined use of solar and geothermal energy not only improves the energy utilization efficiency of the preheating process but also reduces the costs and carbon emissions associated with traditional energy sources (such as electricity and natural gas). Simultaneously, this modular preheating system is highly flexible, allowing for adjustments to the working priority of each module based on seasonal and regional resource differences.

[0079] Preferably, the geothermal heat exchanger is equipped with a three-way valve 1604; the inlet of the three-way valve 1604 is used to receive the heating medium of the geothermal heat exchanger; the outlet of the three-way valve 1604 is respectively connected to the wet saturated steam preheating module 1601 and the molten salt heating module; the opening and closing degree of the three-way valve 1604 to the wet saturated steam preheating module 1601 and the molten salt heating module is controlled by a control device.

[0080] In this embodiment of the invention, the inlet of the three-way valve 1604 is connected to the heating medium of the geothermal heat exchanger, mainly receiving hot fluid (such as geothermal hot water or geothermal steam) from the geothermal well. Through the design of the three-way valve 1604, the heat output from the geothermal heat exchanger can be transferred to the wet saturated steam preheating module 1601 and the molten salt heating module respectively, realizing the efficient utilization and flexible allocation of geothermal resources.

[0081] The outlets of the three-way valve 1604 are connected to the wet saturated steam preheating module 1601 and the molten salt heating module, respectively. The valve opening degree at each outlet is dynamically adjusted according to system operating requirements, thereby regulating the geothermal heat flow to different modules. The wet saturated steam preheating module 1601 is mainly used to heat oilfield produced water, providing stable wet saturated steam for subsequent evaporation units. The molten salt heating module utilizes geothermal heat to supplement the molten salt thermal storage system, providing a continuous heat source for superheated steam production. The three-way valve 1604 is connected to a control device for real-time regulation: the control device dynamically adjusts the opening ratio of the three-way valve 1604 according to steam injection requirements, current system operating status, and the heating capacity of the geothermal fluid, ensuring the optimal geothermal heat distribution.

[0082] Preferably, the control device is configured to: construct a corresponding LSTM model based on historical steam injection data, real-time steam demand, and oil well operating parameters to predict future steam injection demand at a predetermined time; determine the preheating demand for low-temperature water supply based on the steam injection demand and the heat exchange efficiency of the evaporator; determine the supplementary heat exchange power of the geothermal preheating module 1603 for performing low-temperature water supply preheating based on the heat exchange power of the real-time wet saturated steam preheating module 1601 and the solar preheating module 1602; generate a control scheme for the valve opening degree of the three-way valve 1604 leading to the preheating module based on the supplementary heat exchange power of the geothermal preheating module 1603; and generate a control scheme for the valve opening degree of the three-way valve 1604 leading to the molten salt heating module based on the remaining heat exchange power of the geothermal preheating module 1603.

[0083] Furthermore, determining the additional heat exchange power of the geothermal preheating module 1603 performing low-temperature water supply preheating based on the heat exchange power of the real-time wet saturated steam preheating module 1601 and the solar preheating module 1602 includes: constructing a corresponding objective function based on a collaborative game theory algorithm, treating the preheating module and the molten salt heating module as game players, to maximize the steam injection demand satisfaction rate and molten salt thermal storage efficiency; and iteratively solving the objective function using the Lagrange relaxation method to obtain the optimal additional heat exchange power of the geothermal preheating module 1603 performing low-temperature water supply preheating.

[0084] In this embodiment of the invention, dynamic control of the heat distribution between the geothermal preheating module 1603 and the molten salt heating module is achieved through prediction algorithms and optimization strategies, ensuring efficient satisfaction of steam injection demand and the overall economic efficiency of system operation. The core functions of the control device mainly include steam injection demand prediction, determination of low-temperature water supply preheating demand, calculation of the additional heat exchange power to be added to the geothermal preheating module 1603, and generation of a valve control scheme for the three-way valve 1604 based on the heat exchange power distribution. Specifically, this includes the following:

[0085] 1) Steam Injection Demand Forecasting: The control unit first constructs an LSTM (Long Short-Term Memory) model based on historical steam injection data, real-time steam demand, and well operating parameters to predict steam injection demand at specific future moments. Through deep learning of historical data and real-time parameters, the LSTM model can effectively capture the dynamic changes in steam injection demand. For example, when an oil well enters different recovery stages or the ambient temperature changes, steam injection demand may exhibit nonlinear fluctuations, and the LSTM model can provide accurate predictions in advance based on these changes. This predictive function provides a scientific basis for subsequent preheating demand and geothermal energy allocation, ensuring the system's forward-looking and responsive operation.

[0086] 2) Determination of Low-Temperature Feed Water Preheating Requirements: Based on the predicted steam injection demand and the heat exchange efficiency of the evaporator, the control device calculates the preheating requirements for the low-temperature feed water. The heat exchange efficiency of the evaporator directly affects the generation capacity of wet saturated steam, while the degree of preheating of the low-temperature feed water determines the heat load of the evaporator. By comprehensively considering these factors, the control device can accurately determine the target temperature that the low-temperature feed water needs to reach, so as to meet the steam injection demand while reducing the risk of scaling in the evaporator and improving the overall heat exchange efficiency.

[0087] 3) Calculation of supplementary heat exchange power for geothermal preheating module 1603: The control device further combines the real-time heat exchange power of wet saturated steam preheating module 1601 and solar preheating module 1602 to dynamically calculate the supplementary heat exchange power for geothermal preheating module 1603. Wet saturated steam preheating module 1601 utilizes wet saturated steam from the evaporator for heat recovery, while solar preheating module 1602 provides a clean heat source through high-efficiency concentrating technology. However, the heat supply from these two components fluctuates, especially the solar module, which is significantly affected by weather and day / night conditions. Therefore, the control device needs to monitor the heat exchange power of these two modules in real time and calculate the portion that fails to meet the required heat exchange power as the supplementary heat exchange power for geothermal preheating module 1603.

[0088] To optimize this allocation process, the control unit incorporates a cooperative game theory algorithm, treating the preheating module and the molten salt heating module as players, and constructing a corresponding objective function with the goal of maximizing the steam injection demand satisfaction rate and the molten salt thermal storage efficiency. The introduction of cooperative game theory enables the system to dynamically balance the resource allocation of both, ensuring sufficient preheating of the low-temperature feed water while also storing enough heat in the molten salt system for subsequent superheated steam production.

[0089] 4) Optimization of heat exchange power allocation: The control device uses the Lagrange relaxation method to iteratively solve the objective function, obtaining the optimal supplementary heat exchange power for the geothermal preheating module 1603. The Lagrange relaxation method is a mathematical tool suitable for solving complex constrained optimization problems. By introducing relaxation variables, the original objective function is decomposed into easily solvable subproblems, thus approximating the global optimum in multiple iterations. This method can accurately calculate the supplementary power required by the geothermal preheating module 1603, ensuring the economy and effectiveness of resource allocation.

[0090] 5) Generation of Control Scheme for Three-Way Valve 1604: Based on the supplementary heat exchange power of the geothermal preheating module 1603, the control device generates a control scheme for the opening and closing degree of the three-way valve 1604 leading to the preheating module. Simultaneously, based on the remaining heat exchange power of the geothermal preheating module 1603, a control scheme for the opening and closing degree of the three-way valve 1604 leading to the molten salt heating module is generated. The dynamic regulation of the three-way valve 1604 is executed in real time by the control device to ensure the rational allocation of geothermal resources among different modules. The preheating module prioritizes meeting the preheating needs of the low-temperature water supply, while the molten salt heating module utilizes the remaining geothermal energy for heat storage, providing a supplementary heat source for the production of superheated steam.

[0091] Based on the present invention, the control device can capture the dynamic changes in steam injection demand in advance through the prediction function of the LSTM model, making the system operation more intelligent and precise, and effectively reducing heat waste and insufficient heating. The introduction of the cooperative game theory algorithm ensures the optimal allocation of geothermal resources between the preheating module and the molten salt heating module, which not only meets the current steam injection demand, but also provides reserve heat for subsequent steam production. The optimization solution of the Lagrange relaxation method makes the heat exchange power allocation more efficient, thereby reducing the excessive consumption of geothermal resources and other energy sources and lowering the system's operating costs. Through the dynamic control of the three-way valve 1604, the control device can adapt to the fluctuations in steam injection demand and heat exchange module performance in real time, ensuring the stable operation of the system under various operating conditions. Combining the clean heat source of wet saturated steam and the solar preheating module 1602, the control device minimizes the dependence on traditional energy sources and improves the system's environmental friendliness.

[0092] Specifically, the objective function is expressed as:

[0093] Wherein, ω1 and ω2 represent the preset weighting factors for the importance of produced water preheating requirements and molten salt thermal storage requirements, respectively; Q 地热采 The geothermal heat supply allocated for preheating produced water; Q 采 Total preheating requirements for produced water; Q 地热盐 Q is the geothermal heat supplied for molten salt heating; 盐目标 The target requirement for heating molten salt.

[0094] Preferably, the evaporation device includes multiple heat exchangers; each heat exchanger is connected in series via a pipe, with the water inlet of the first heat exchanger connected to the water outlet of the water supply device, and the water outlet of the last heat exchanger being the outlet of the wet saturated steam; the molten salt flow pipe 19 flows from the last heat exchanger to the first heat exchanger and flows back from the first heat exchanger to the molten salt heating module.

[0095] In this embodiment of the invention, the evaporation device consists of multiple heat exchangers connected in series via pipes, forming a highly efficient staged heating and evaporation system. The inlet of the first heat exchanger is connected to the outlet of a water supply device, which provides preheated, low-temperature water that begins primary heating upon entering the first heat exchanger. Through the sequential action of multiple heat exchangers, the water temperature gradually increases, approaching saturation, until the last heat exchanger heats the water to a wet saturated steam state, completing the evaporation process. The final wet saturated steam is then transported through the outlet to a subsequent steam-water separator or superheater to meet the needs of the steam injection system. To ensure heat exchange efficiency and full utilization of molten salt heat, the evaporation device is equipped with a molten salt flow pipe 19. This pipe flows from the last heat exchanger to the first, creating a highly efficient heat gradient within the evaporation device through a reverse heat transfer mechanism. The molten salt cools down from the last stage heat exchanger, gradually transferring heat to the preceding stages, ensuring maximum utilization of thermal energy within the system. Finally, the molten salt flows back from the first heat exchanger to the molten salt heating module, is reheated, and is recycled.

[0096] Preferably, the superheated steam generating device includes: a steam-water separator for separating the incoming wet saturated steam into dry steam and saturated water respectively; the dry steam and saturated water output from the steam-water separator are connected to the superheater and the mixer respectively through a dry steam pipe and a separated water pipe; the superheater performs heat exchange with the molten salt flow pipe 19 to convert the dry steam into superheated steam.

[0097] Furthermore, the superheater is connected to another inlet of the mixer via a first superheated steam pipeline to collect superheated steam into the mixer; the mixer is used to perform superheated steam and saturated water mixing based on the gas injection requirements to obtain superheated steam that meets the gas injection requirements, and outputs the superheated steam to the steam injection well via a second superheated steam pipeline.

[0098] In this embodiment of the invention, the superheated steam generator, through a combination of a steam-water separator, a superheater, and a mixer, achieves precise conversion of wet saturated steam into superheated steam that meets the steam injection requirements, providing efficient and stable steam output for the steam injection well. The steam-water separator is one of the core components of the entire device, responsible for separating the wet saturated steam from the water. During the separation process, the wet saturated steam is separated into dry steam and saturated water based on the density difference between steam and liquid water. This process not only improves the steam quality but also provides a suitable working fluid for subsequent superheating and mixing processes. The dry steam output from the steam-water separator is transported to the superheater for further heating via a dry steam pipeline, while the separated saturated water is transported to the mixer via a separated water pipeline, ready to be mixed with the superheated steam.

[0099] Furthermore, the superheater heats the dry steam to a high superheat state through heat exchange with the molten salt flow pipe 19, thereby generating high-quality superheated steam. The molten salt flow pipe 19 serves as a heat source, utilizing the stable heat supply from the high-temperature molten salt to achieve efficient heating of the dry steam. This design not only ensures that the temperature of the superheated steam meets the requirements of the injection well but also effectively reduces energy consumption. The superheated steam output from the superheater is transported to the mixer through the first superheated steam pipe, where it is mixed with saturated water transported through the separation water pipe in the required proportion. The mixer's function is to precisely mix the high-superheated superheated steam and saturated water according to real-time injection requirements, generating target superheated steam that meets downhole conditions. By adjusting the mixing ratio of superheated steam and saturated water, the temperature and pressure of the mixed steam can be precisely controlled, ensuring the efficiency and stability of the injection process. The generated target superheated steam is transported to the injection well through the second superheated steam pipe, providing the necessary thermal energy support for heavy oil extraction.

[0100] Preferably, the control device is configured to: construct a corresponding heat balance model and flow balance model based on the state information of the superheated steam and saturated water entering the mixer; determine the mixing ratio of superheated steam and saturated water based on the heat balance model and flow balance model; and adjust the valve opening of the mixer in real time according to the mixing ratio.

[0101] Specifically, the heat balance model is expressed as: m 混合 *h 混合 =m 过热 *h 饱和 +m 饱和 *h 饱和

[0102] The flow balance model is expressed as: m 混合 =m 过热 +m 饱和

[0103] Where, m 混合 m 过热and m 饱和 These are the mass flow rates of the mixed steam, superheated steam, and saturated water, respectively; h 混合 h 过热 and h 饱和 These are the specific enthalpy of mixed steam, the specific enthalpy of superheated steam, and the specific enthalpy of saturated water, respectively.

[0104] Furthermore, the mixing ratio of superheated steam and saturated water is determined based on the heat balance model and the flow balance model, including: performing a joint solution based on the heat balance model and the flow balance model to obtain the flow ratio of superheated steam and saturated water, so as to determine the mixing ratio of superheated steam and saturated water.

[0105] In this embodiment of the invention, the control device is configured to construct corresponding heat balance and flow balance models based on the real-time state information of the superheated steam and saturated water fed into the mixer, thereby achieving dynamic control of the mixing ratio of superheated steam and saturated water. The heat balance model is used to calculate the energy distribution of the mixed steam, ensuring that the temperature and pressure of the output steam meet the steam injection requirements, while the flow balance model is used to determine the mass flow rate ratio of superheated steam and saturated water during the mixing process, ensuring the accuracy of the total steam flow rate. Based on these two models, the control device can adjust the opening and closing degree of the valves in the mixer in real time, thereby dynamically achieving optimal mixing of superheated steam and saturated water.

[0106] In the heat balance model, the system calculates the energy composition of the mixed steam by monitoring the enthalpy (i.e., heat per unit mass) of the mixed steam, superheated steam, and saturated water. The goal of the heat balance model is to ensure that the enthalpy of the mixed steam matches the steam injection demand, thereby meeting the oil well's requirements for steam temperature. This model fully considers the initial states of the superheated steam and saturated water (such as temperature, pressure, and enthalpy) and dynamically updates its parameters to adapt to real-time changes in steam injection demand.

[0107] The flow balance model is used to ensure the material conservation of the system. By accurately calculating the total flow rate of the mixed steam and combining it with the heat balance model, the flow ratio of superheated steam and saturated water is further determined. The core of this model is to ensure that the total flow rate of the mixed steam is consistent with the steam injection demand, while avoiding the overuse of superheated steam or saturated water and optimizing resource utilization efficiency.

[0108] Based on the heat balance model and the flow balance model, the control device can dynamically determine the mixing ratio of superheated steam and saturated water through joint solution. Specifically, the control device monitors the state parameters of the superheated steam and saturated water input to the mixer in real time, and calculates the required mixing ratio based on the steam injection demand. Subsequently, the opening and closing degree of the valves in each channel of the mixer is adjusted according to the calculation results to ensure that the temperature, pressure and flow rate of the mixed steam are consistent with the target values.

[0109] Preferably, after adjusting the valve opening of the mixer in real time according to the mixing ratio, the control device is further configured to: collect the state parameters of the superheated steam required for steam injection in real time, and identify the deviation value between the superheated steam and the state parameters of the target superheated steam; and execute a PID control algorithm based on the deviation value to correct the valve opening of the mixing device, so as to keep the deviation value between the actual superheated steam state parameters and the target superheated steam state parameters within a preset difference threshold range.

[0110] In this embodiment of the invention, after initial valve opening adjustment based on the mixing ratio, the control device further optimizes the control process by real-time monitoring of the superheated steam state parameters required for steam injection and identifying the deviation between the actual superheated steam state parameters and the target superheated steam state parameters. To achieve this, the control device introduces a PID (Proportional-Integral-Derivative) control algorithm to dynamically correct the valve opening of the mixer, ensuring that the actual output superheated steam state always remains consistent with the target requirements.

[0111] Specifically, the control unit first collects key state parameters of the superheated steam output during the steam injection process in real time through a sensor network, such as temperature, pressure, and flow rate. These parameters directly affect the thermal efficiency and oil recovery effect of downhole steam injection, making their accuracy crucial. Simultaneously, the control unit presets the parameter range for the target superheated steam, defining these parameter values ​​based on downhole requirements and real-time adjusted injection targets. Subsequently, the control unit calculates the deviation between the actual and target parameters, identifying issues such as insufficient temperature, pressure deviation, or unstable flow rate. Once a deviation exceeds a preset threshold, the control unit immediately activates the PID control algorithm. The PID algorithm uses proportional control to quickly respond to large deviations, integral control to eliminate accumulated errors, and derivative control to suppress rapid system fluctuations, resulting in smoother and more precise control adjustments. Based on the PID algorithm's calculations, the control unit further optimizes the opening of each valve within the mixer, including adjusting the flow rate ratio between the superheated steam channel and the saturated water channel, thereby gradually eliminating deviations.

[0112] The dynamic correction function of PID control can adapt to changes in steam injection demand under complex operating conditions. For example, when downhole steam injection demand fluctuates due to changes in the external environment or well conditions, PID control can quickly adjust within milliseconds to ensure that the temperature, pressure, and flow rate of the output steam always meet the requirements. Furthermore, PID control, through real-time feedback adjustment, effectively avoids the over-adjustment or lag problems that may occur in traditional fixed proportional control.

[0113] In one possible implementation, as shown in Figure 3, a schematic diagram of a molten salt heating superheated steam generation system is provided. For ease of explanation of the system's operation, the water supply device only preheats the system with steam. The system comprises a preheated water pipe 1 (water supply device), an evaporator 2 (evaporation device), a steam extraction pipe 3, a first wet steam pipe 4, a second wet steam pipe 5, a second hot salt pipe 6, a steam-water separator 7 (superheated steam generation device), a separated water pipe 8, a dry steam pipe 9, a superheater 10, a first superheated steam pipe 11, a mixer 12, a second superheated steam pipe 13, a first hot salt pipe 14, a cold salt pipe 15, a preheating module 16, a water supply pipe 17, and a condensate pipe 18.

[0114] The working principles and processes of each part of the system are as follows, in conjunction with the embodiments.

[0115] 1. The main equipment of this invention consists of a preheating module 16, an evaporation device 2, a steam-water separator 7, a superheater 10, and a mixer 12.

[0116] 2. The produced water from the oilfield is connected to the preheating module 16 through the water supply pipeline 17. After being heated in the preheating module 16, the produced water is connected to the evaporation device 2 through the preheated water pipeline 1. Taking the use of binary molten salt as an example, the freezing point of the binary molten salt is 220℃, the water supply temperature of the produced water from the oilfield is 40-70℃, and the preheated water temperature is 230-250℃. The silicon content of the produced water from the oilfield can be <250mg / L.

[0117] 3. Evaporation device 2 can consist of one or more heat exchangers; if intermediate adjustment is not considered, the evaporation device can be equipped with only one heat exchanger, and if intermediate adjustment is considered, the evaporation device can be equipped with two or more heat exchangers.

[0118] 4. The produced water from the oilfield is heated by molten salt in the evaporation unit 2 to become wet saturated steam. The wet saturated steam is transported out through the first wet steam pipeline 4. Part of the wet saturated steam is connected to the preheating module 16 through the extraction steam pipeline 3 to heat the produced water in the preheating module. The other part of the wet saturated steam is connected to the steam-water separator 7 through the second wet steam pipeline 5. The parameters of the wet saturated steam produced by the evaporation unit can be 8MPa, 295℃, and dryness 75%.

[0119] 5. The wet saturated steam heated by the oilfield produced water in the preheating module 16 releases heat and turns into condensate in the preheating module 16; the temperature of the condensate is below 80℃.

[0120] 6. The wet saturated steam connected to the steam-water separator 7 is partially converted into dry steam and partially into saturated water. The dry steam parameters can be 99%-100% dryness, 75% dry steam mass, and 25% saturated water mass.

[0121] 7. The saturated water separated from the steam-water separator 7 is connected to the mixer 12 via the separated water pipe 8.

[0122] 8. The dry steam separated from the steam-water separator 7 is connected to the superheater 10 via the dry steam pipe 9. In the superheater 10, the dry steam is heated by high-temperature molten salt to become superheated steam with a high degree of superheat; the superheat of the superheated steam with a high degree of superheat can be 135℃.

[0123] 9. The superheated steam with high superheat generated in the superheater 10 is connected to the mixer 12 via the first superheated steam pipe 11.

[0124] 10. In the mixer 12, high-superheated superheated steam and saturated water are mixed to become low-superheated superheated steam, which is then transported to the steam injection well through the second superheated steam pipeline 13; the superheat of the low-superheated superheated steam can be 15-20℃.

[0125] 11. Molten salt serves as the heat source medium for the system. High-temperature molten salt is connected to the superheater 10 via the first hot salt pipe 14 to heat dry steam into superheated steam with a high degree of superheat. Then, it is connected to the evaporator 2 via the second hot salt pipe 6 to heat preheated water into wet saturated steam. Finally, it is discharged from the system via the cold salt pipe 15. Taking binary molten salt as an example, the high-temperature molten salt temperature can be 560℃, and the low-temperature molten salt temperature after heat exchange can be 285℃.

[0126] Figure 4 is a flowchart of a method for controlling a molten salt heating superheated steam generation system according to an embodiment of the present invention. As shown in Figure 4, this embodiment of the present invention provides a method for controlling a molten salt heating superheated steam generation system, the method comprising:

[0127] Step S10: Collect real-time steam injection demand information, and perform target operation state simulations for the water supply device, evaporation device, and superheated steam generator based on the steam injection demand information;

[0128] Step S20: Based on the deviation between the real-time operating status of the water supply device, the evaporation device, and the superheated steam generator and the corresponding target operating status, generate control schemes for the water supply device, the evaporation device, and the superheated steam generator respectively.

[0129] Step S30: Execute the control scheme to adjust the status of the water supply device, evaporation device and superheated steam generator respectively.

[0130] Preferably, the water supply device includes: a water supply pipeline for inputting oilfield produced water as low-temperature water for the water supply device; a preheating module connected to the water supply pipeline for preheating the low-temperature water; and the preheating module connected to an evaporation device via a pipeline for transmitting the preheated low-temperature water to the evaporation device.

[0131] Preferably, the preheating module includes: a wet saturated steam preheating module 1601, a solar preheating module 1602, and a geothermal preheating module 1603, combined for preheating the low-temperature supply water; the wet saturated steam of the wet saturated steam preheating module 1601 is obtained by separating the wet saturated steam output from the evaporator and flows into the wet saturated steam preheating module 1601 via an extraction steam pipe; another portion of the wet saturated steam output from the evaporator flows into the steam-water separator via a second wet steam pipe; the solar preheating module 1602 includes: a concentrating solar collector, disposed between the wet saturated steam preheating module 1601 and the water supply pipe, for use... The geothermal energy preheating module 1603 is used to perform the first stage of preheating on the low-temperature water supply. It includes a geothermal heat exchanger, arranged parallel to the concentrating solar collector, which, in combination with the concentrating solar collector, performs the first stage of preheating on the low-temperature water supply. The geothermal heat exchanger is equipped with a three-way valve 1604. The inlet of the three-way valve 1604 is used to receive the heating medium from the geothermal heat exchanger. The outlet of the three-way valve 1604 is connected to both the wet saturated steam preheating module 1601 and the molten salt heating module. The opening and closing degrees of the three-way valve 1604 to the wet saturated steam preheating module 1601 and the molten salt heating module are controlled by a control device.

[0132] Preferably, the generation rule for the control scheme of the preheating module is as follows: based on historical steam injection data, real-time steam demand, and oil well operating parameters, a corresponding LSTM model is constructed to predict the steam injection demand at a predetermined time in the future; based on the steam injection demand and the heat exchange efficiency of the evaporator, the preheating demand for low-temperature water supply is determined; based on the heat exchange power of the real-time wet saturated steam preheating module 1601 and the solar preheating module 1602, the supplementary heat exchange power of the geothermal energy preheating module 1603 performing low-temperature water supply preheating is determined; based on the supplementary heat exchange power of the geothermal energy preheating module 1603, a control scheme for the valve opening degree of the three-way valve 1604 leading to the preheating module is generated, and based on the remaining heat exchange power of the geothermal energy preheating module 1603, a control scheme for the valve opening degree of the three-way valve 1604 leading to the molten salt heating module is generated, which serves as the control scheme for the preheating module.

[0133] The present invention also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described control method for a molten salt heating superheated steam generation system.

[0134] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0135] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe the various possible combinations.

[0136] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the embodiments of the present invention, they should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A molten salt heating superheated steam generation system control method, characterized by, The method is applied to a molten salt heated superheated steam generation system, which includes a water supply device, an evaporation device, and a superheated steam generation device connected in sequence; a molten salt heating module for supplying heat to the evaporation device and the superheated steam generation device; and a control device for controlling the operating status of the water supply device, the evaporation device, and the superheated steam generation device based on steam injection requirements. The method includes: Real-time steam injection demand information is obtained, and target operating state simulations of the water supply unit, evaporation unit, and superheated steam generator are performed based on the steam injection demand information; wherein, The steam injection demand information is obtained by constructing a corresponding LSTM model based on historical steam injection data, real-time steam demand, and oil well operating parameters. Based on the deviation between the real-time operating status of the water supply device, evaporation device, and superheated steam generator and the corresponding target operating status, control schemes for the water supply device, evaporation device, and superheated steam generator are generated respectively. The control scheme is executed to adjust the status of the water supply device, evaporation device, and superheated steam generator, respectively.

2. The method of claim 1, wherein, The water supply device includes: Water supply pipes are used to input water, serving as the low-temperature water supply for water supply devices; The preheating module, connected to the water supply pipeline, is used to preheat the low-temperature water supply. The preheating module is connected to the evaporation device via a pipe and is used to transfer the preheated low-temperature supply water to the evaporation device.

3. The method of claim 2, wherein, The preheating module includes: A wet saturated steam preheating module, a solar preheating module, and a geothermal preheating module are combined to perform preheating of low-temperature supply water. The wet saturated steam in the wet saturated steam preheating module is obtained by separating the wet saturated steam output from the evaporator and then entering the wet saturated steam preheating module via the extraction steam pipeline. Another portion of the wet saturated steam output from the evaporator is fed into the steam-water separator via a second wet steam pipeline. The solar preheating module includes: A concentrating solar collector is installed between the wet saturated steam preheating module and the water supply pipeline to perform the first stage of preheating for the low-temperature supply water. The geothermal energy preheating module includes: The geothermal heat exchanger is arranged in parallel with the concentrating solar collector and, in combination with the concentrating solar collector, performs the first stage of preheating for the low-temperature supply water. The geothermal heat exchanger is equipped with a three-way valve; The inlet of the three-way valve is used to receive the heating medium from the geothermal heat exchanger; The outlet of the three-way valve is connected to the wet saturated steam preheating module and the molten salt heating module, respectively. The opening and closing degree of the three-way valves, which connect to the wet saturated steam preheating module and the molten salt heating module respectively, is controlled by a control device.

4. The method of claim 3, wherein, The control device is also used to generate a control scheme for the preheating module based on the steam injection requirements; The generation rules for the control scheme of the preheating module are as follows: Based on historical steam injection data, real-time steam demand, and oil well operating parameters, a corresponding LSTM model is constructed to predict the steam injection demand at a predetermined future time. Based on the steam injection requirements and the heat exchange efficiency of the evaporator, the preheating requirements for low-temperature water supply are determined. Based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module, the additional heat exchange power to be added to the geothermal energy preheating module that performs low-temperature water supply preheating is determined. A control scheme for the opening and closing degree of the three-way valve leading to the preheating module based on the supplementary heat exchange power generated by the geothermal energy preheating module, and a control scheme for the opening and closing degree of the three-way valve leading to the molten salt heating module based on the remaining heat exchange power of the geothermal energy preheating module, are used as the control scheme for the preheating module.

5. The method of claim 4, wherein, The determination of the additional heat exchange power to be provided by the geothermal preheating module performing low-temperature water supply preheating, based on the heat exchange power of the real-time wet saturated steam preheating module and the solar preheating module, includes: Based on the collaborative game theory algorithm, the preheating module and the molten salt heating module are regarded as the players in the game, and the corresponding objective function is constructed to maximize the steam injection demand satisfaction rate and the molten salt thermal storage efficiency. The objective function is iteratively solved using the Lagrange relaxation method to obtain the optimal heat exchange power to be supplemented for the geothermal energy preheating module with low-temperature water supply preheating.

6. The method of claim 5, wherein, The objective function is expressed as: Wherein, ω1 and ω2 represent the preset weighting factors for the importance of produced water preheating requirements and molten salt thermal storage requirements, respectively; Q 地热采 Q is the amount of geothermal heat supply assigned to the preheating of produced water; Q 采 total produced water preheat requirement; Q 地热盐 Q is the amount of geothermal heat supply assigned to molten salt heating; Q 盐目标 The target requirement for molten salt heating.

7. The method of claim 1, wherein, The evaporation device includes multiple heat exchangers; Each heat exchanger is connected in series via pipes. The inlet and outlet of the first heat exchanger are connected, and the outlet of the last heat exchanger is the outlet of the wet saturated steam. The molten salt flow pipe flows from the last heat exchanger to the first heat exchanger, and then flows back from the first heat exchanger to the molten salt heating module.

8. The method of claim 1, wherein, The superheated steam generator includes: A steam-water separator is used to separate incoming wet saturated steam into dry steam and saturated water. The dry steam and saturated water output from the steam-water separator are connected to the superheater and mixer through the dry steam pipeline and the separated water pipeline, respectively. The superheater exchanges heat with the first hot salt pipe to convert dry steam into superheated steam.

9. The method of claim 8, wherein, The superheater is connected to another inlet of the mixer via a first superheated steam pipe to allow superheated steam to flow into the mixer; The mixer is used to mix superheated steam and saturated water based on the gas injection requirements to obtain superheated steam that meets the injection requirements, and outputs the superheated steam to the injection well through a second superheated steam pipeline.

10. The method of claim 9, wherein, The control device is configured to: Based on the state information of the superheated steam and saturated water entering the mixer, the corresponding heat balance model and flow balance model are constructed. The mixing ratio of superheated steam and saturated water was determined based on the heat balance model and the flow balance model. The valve opening of the mixer is adjusted in real time according to the mixing ratio.

11. The method of claim 10, wherein, The heat balance model is represented as: m 混合 *h 混合 = m 过热 *h 饱和 + m 饱和 *h 饱和 The flow balance model is expressed as follows: m 混合 = m 过热 + m 饱和 wherein m 混合 , m 过热 , and m 饱和 are the mass flow rate of mixed steam, the mass flow rate of superheated steam, and the mass flow rate of saturated water, respectively; h 混合 , h 过热 and h 饱和 are the specific enthalpy of mixed steam, the specific enthalpy of superheated steam and the specific enthalpy of saturated water, respectively.

12. The method of claim 10, wherein, The mixing ratio of superheated steam and saturated water is determined based on heat balance and flow balance models, including: By performing a joint solution based on the heat balance model and the flow balance model, the flow ratio of superheated steam to saturated water is obtained, so as to determine the mixing ratio of superheated steam and saturated water.

13. The method of claim 11, wherein, After adjusting the valve opening of the mixer in real time according to the mixing ratio, the control device is further configured to: The state parameters of superheated steam required for steam injection are collected in real time, and the deviation between them and the state parameters of the target superheated steam is identified. Based on the deviation value, a PID control algorithm is executed to correct the valve opening of the blending device, so as to keep the deviation between the actual superheated steam state parameters and the target superheated steam state parameters within the preset difference threshold range.

14. A fused salt heated superheated steam generating system characterized by, The system is used to execute the control method of the molten salt heating superheated steam generation system according to any one of claims 1-13, the system comprising: A water supply device, an evaporation device, and a superheated steam generator are connected in sequence. A molten salt flow pipe is provided from the superheated steam generator to the evaporator to provide a heat source to the superheated steam generator and the evaporator. The water supply device is used to preheat the low-temperature water supply and transfer the preheated low-temperature water supply to the evaporation device so that the evaporation device converts the preheated low-temperature water supply into wet saturated steam. The superheated steam generator is used to convert the wet saturated steam into superheated steam for injection. The control device is used to control the operating status of the water supply device, evaporation device and superheated steam generator based on the steam injection demand.

15. The system of claim 14, wherein, The water supply device includes: Water supply pipelines are used to provide low-temperature water to water supply devices, with oilfield produced water being the preferred low-temperature water source. The preheating module, connected to the water supply pipeline, is used to preheat the low-temperature water supply. The preheating module is connected to the evaporation device via a pipe and is used to transfer the preheated low-temperature supply water to the evaporation device.

16. The system of claim 15, wherein, The preheating module includes: A wet saturated steam preheating module, a solar preheating module, and a geothermal preheating module are combined to perform preheating of low-temperature supply water. The wet saturated steam in the wet saturated steam preheating module is obtained by separating the wet saturated steam output from the evaporator and then entering the wet saturated steam preheating module via the extraction steam pipeline. Another portion of the wet saturated steam output from the evaporator is fed into the steam-water separator via a second wet steam pipeline.

17. The system of claim 16, wherein, The solar preheating module includes: A concentrating solar collector is installed between the wet saturated steam preheating module and the water supply pipeline to perform the first stage of preheating for the low-temperature supply water. The geothermal energy preheating module includes: The geothermal heat exchanger is arranged in parallel with the concentrating solar collector and, in combination with the concentrating solar collector, performs the first stage of preheating for the low-temperature supply water.

18. The system of claim 17, wherein, The geothermal heat exchanger is equipped with a three-way valve; The inlet of the three-way valve is used to receive the heating medium from the geothermal heat exchanger; The outlet of the three-way valve is connected to the wet saturated steam preheating module and the molten salt heating module, respectively. The opening and closing degree of the three-way valves, which connect to the wet saturated steam preheating module and the molten salt heating module respectively, is controlled by a control device.

19. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed on a computer, cause the computer to perform the control method for the molten salt heating superheated steam generation system as described in any one of claims 1-13.

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