Mobile heat storage steam injection system and method of heat storage steam injection

Abstract

A mobile heat storage steam injection system and a heat storage steam injection method. The steam injection boiler used in the prior art produces a large amount of CO2 emission during the mining process, which does not meet the new goal of carbon peak and carbon neutralization. The composition of the present application comprises: two mobile trailers (1), a group of trailer floors (2), two said mobile trailers are installed on the trailer floor and are respectively installed at both ends of the said trailer floor, wherein the adjacent said trailer floors are connected through the connecting fixing device (3), the said mobile trailer is respectively provided with a control room I, a steam generation area II and a heat storage area III, the said control room I is the integrated control center of the said steam generation area II and the said heat storage area III, the said control room I is provided with a matched control operation and monitoring system, the said control room I and the said steam generation area II are respectively provided with a door (4), and the outer layer of the said heat storage area III is wrapped with a heat preservation layer (15). The present application is used for mobile heat storage steam injection system.

Description

Technical Field

[0001] This invention relates to the field of oilfield development and clean energy utilization technology, specifically to a method for thermal storage and steam injection in a mobile thermal storage and steam injection system. Background Technology

[0002] Achieving carbon emission reduction while ensuring oil extraction needs has become a new goal for the oil extraction industry. Heavy oil, due to its high density, high viscosity, and poor fluidity, presents a significant challenge and a key focus for the industry. Thermal recovery is commonly used for heavy oil extraction, which involves injecting high-temperature, high-pressure steam into the oil. Under high temperatures, the oil undergoes cracking, reducing the content of heavy components and decreasing viscosity, thus simplifying extraction. However, this process consumes a very large amount of steam; typically, extracting one ton of heavy oil requires approximately eight tons of steam.

[0003] In areas with a high density of thermal wells, stationary steam injection boilers that burn fossil fuels are typically used for heavy oil extraction. A small number of these methods utilize solar thermal conversion to drive steam, but the initial investment costs are very high, and they are difficult to apply to oil production projects with dispersed thermal wells. If direct-drive electric storage boilers are used, the pressure requirements for steam injection are difficult to meet due to technical limitations.

[0004] Current technology uses mobile steam injection boilers, which will result in a large amount of CO2 emissions during the extraction process of such oilfield projects, which does not meet the new goals of carbon peaking and carbon neutrality. Summary of the Invention

[0005] The purpose of this invention is to provide a mobile thermal storage steam injection system and a thermal storage steam injection method. This structure and method utilize new energy power such as photovoltaic and wind power, as well as off-peak electricity from the power grid, to heat the thermal storage medium and store it in a mobile thermal storage device. When steam is needed, it is connected to a steam generator to achieve continuous steam supply.

[0006] The above objectives are achieved through the following technical solutions:

[0007] A mobile thermal storage and steam injection system comprises: two mobile trailers and a set of trailer base plates. The two mobile trailers are mounted on the trailer base plates and respectively installed at both ends of the trailer base plates. Adjacent trailer base plates are connected by a connecting and fixing device. Each mobile trailer is equipped with a control room I, a steam generation zone II, and a thermal storage zone III. The control room I is the integrated control center for the steam generation zone II and the thermal storage zone III. The control room I is equipped with a matching control operation and monitoring system. Doors are installed on both sides of the control room I and the steam generation zone II. The thermal storage zone III is covered with an insulation layer.

[0008] The mobile thermal storage steam injection system includes a steam generation zone II comprising a feedwater preheating device, which is connected to a steam generator, an electric heating / preheating device, and an external feedwater supply. The steam generator is connected to a steam-water separator via a preheating shut-off valve, and the steam-water separator is connected to the steam injection outlet. The electric heating / preheating device is connected to the steam generator via a circulating pump.

[0009] The mobile thermal storage and steam injection system has a steam generation zone II with a heat source medium inlet I and a heat source medium inlet II. The heat source medium inlet I and the heat source medium inlet II are respectively connected to the steam generating device through molten salt inlet shut-off valve I and molten salt inlet shut-off valve II. The steam generating device is connected to the feedwater preheating device, and the feedwater preheating device is connected to the heat source medium outlet.

[0010] In the mobile thermal storage steam injection system, when the thermal storage zone III uses single-tank molten salt thermal storage, a molten salt pump and a hot molten salt inlet are installed at the top of the thermal storage zone III, and a cold molten salt inlet and a salt discharge valve are installed at the bottom. The molten salt pump is connected to the hot molten salt outlet, and both the hot molten salt inlet and the cold molten salt inlet are equipped with molten salt distribution rings. The molten salt distribution rings have multiple sets of connecting pipes. When the thermal storage zone III uses dual-tank molten salt thermal storage, an electric heater should be installed at the bottom of the thermal storage zone III, and the suction port of the long-shaft molten salt pump is located at the lower part of the thermal storage zone III.

[0011] In the mobile thermal storage steam injection system, when the thermal storage zone III adopts solid thermal storage, the solid thermal storage material is magnesia brick, granite, concrete, or composite phase change material. An axial flow fan and a cold air inlet are respectively installed on both sides of the bottom of the thermal storage zone III, and a hot air outlet is installed above it. The cold air inlet and the hot air outlet are respectively connected to a gate valve.

[0012] A mobile thermal energy storage steam injection system and a thermal energy storage steam injection method, the method comprising the following steps:

[0013] First, when the mobile thermal storage steam injection system is working, the heat source medium enters the steam generator and the feedwater preheating device in sequence. The water is first heated to a certain temperature by the feedwater preheating device, and then enters the steam generator to generate saturated steam. The steam enters the steam-water separator for separation.

[0014] When the heat storage medium in heat storage zone III is molten salt, because molten salt will solidify when the temperature is below 150-230℃, the water temperature in the feed water preheating device, steam generator and its equipment needs to be preheated before the heat source medium enters the steam generation system. The process is to close the preheating shut-off valve, turn on the circulating pump and the electric heating / preheating device, and heat the water to a certain temperature by circulating between the circulating pump, the electric heating / preheating device, the feed water preheating device and the steam generator. Only after the water temperature is heated to a certain temperature can the molten salt inlet shut-off valve I or the molten salt inlet shut-off valve II be opened so that the steam generation zone II can work normally.

[0015] When the heat storage medium in heat storage zone III is molten salt, if the temperature of the external feed water is lower than the freezing point of the molten salt, the circulating pump and the electric heating / preheating device can be turned on to raise the water temperature entering the feed water preheating device in order to avoid molten salt solidification.

[0016] Steam generation zone II has two heat source medium inlets I and II, as well as molten salt inlet shut-off valves I and II. When the mobile thermal storage steam injection system is working normally, it can enter from only one of the thermal storage medium inlets. The molten salt inlet shut-off valves corresponding to the working heat source medium inlet is opened, and the other set is closed.

[0017] (1) When the single-tank molten salt thermal storage technology is adopted in thermal storage zone III, the molten salt pump inlet should be located at the upper part of thermal storage zone III. During operation, hot molten salt is drawn from the upper part of thermal storage zone III and sent to the heat source medium inlet of steam generation zone II through the hot molten salt outlet. Hot molten salt can be replenished to thermal storage zone III through the hot molten salt inlet. Molten salt cooled by steam generation zone II enters thermal storage zone III through the cold molten salt inlet. A salt drain valve is installed at the bottom of thermal storage zone III. In case of an accident or during maintenance of thermal storage zone III, the salt drain valve can be opened to drain the hot molten salt from thermal storage zone III. Molten salt; both the hot molten salt inlet and the cold molten salt inlet should be equipped with molten salt distribution rings. The molten salt distribution rings consist of multiple sets of connecting pipes with small holes to ensure that the molten salt enters the heat storage zone III uniformly and at a low speed, so as to avoid damaging the temperature slope layer of the single-tank molten salt heat storage technology and ensure that the hot molten salt is always in the upper part of the heat storage zone III, and the cooled molten salt is located in the lower part of the heat storage zone III. Electric heaters can be installed at appropriate locations in the heat storage zone III to compensate for heat loss, or direct electric heating energy storage can be carried out when there is a small amount of hot molten salt in the heat storage zone III.

[0018] (2) When the thermal storage zone III adopts the dual-tank molten salt thermal storage technology, a long-shaft molten salt pump is installed at the top of thermal storage zone III and a salt discharge valve is installed at the bottom; the suction port of the long-shaft molten salt pump should be located at the bottom of thermal storage zone III to ensure that the maximum amount of molten salt can be used, and the hot molten salt outlet is sent to the heat source medium inlet of steam generation zone II; hot molten salt can be replenished to thermal storage zone III through the hot molten salt inlet; during operation, there are two molten salt thermal storage tanks on site, one full tank and one empty tank. The empty tank is used to hold the molten salt cooled by steam generation zone II; an electric heater should be installed at the bottom of thermal storage zone III to compensate for heat loss;

[0019] (3) When solid heat storage technology is used in heat storage zone III, the solid heat storage material can be magnesium brick, granite, concrete, or composite phase change material. The material should be stacked with certain gaps to allow air flow. An axial flow fan is installed at the bottom of heat storage zone III to drive the air to carry away the heat of the solid heat storage material and heat the air. When steam generation zone II is working, the gate valve needs to be opened so that hot air can flow out from the hot air outlet and the cold air after heat exchange flows into the heat storage zone from the cold air inlet to be reheated. Electric heaters should be reasonably arranged inside the solid heat storage material to heat the solid heat storage material during heat storage.

[0020] Beneficial effects:

[0021] 1. The present invention relates to a mobile thermal energy storage steam injection system and a thermal energy storage steam injection method. This structure and method solve the steam demand of decentralized thermal recovery wells without using fossil energy, thereby replacing traditional mobile steam injection boilers, reducing CO2 emissions, and fully meeting the new goals of carbon peaking and carbon neutrality.

[0022] 2. This invention proposes a method to use new energy power such as photovoltaic and wind power, as well as off-peak electricity from the power grid, to heat the thermal storage medium and store it in a mobile thermal storage device. When steam is needed, it is connected to a steam generator to achieve continuous steam supply.

[0023] 3. The system of the present invention consists of a control room I, a steam generation zone II, and a heat storage zone III. The control room I is mainly used to monitor and debug the operation parameters of the steam generation zone II and the heat storage zone III, and to control their operation. The steam generation zone II uses the heat from the heat storage zone III to heat the feedwater and generate high-temperature and high-pressure steam. The heat storage zone III is mainly used to store the heat energy converted from new energy power such as photovoltaic and wind power, as well as off-peak electricity from the power grid, to ensure a continuous and stable supply of heat energy to the steam generation zone II and to avoid load fluctuations and shutdowns in the steam generation zone II.

[0024] 4. This invention replaces the traditional steam injection boiler in the oil extraction industry with a series of devices in steam generation zone II, uses new energy power such as wind power and photovoltaic power to heat the energy storage medium, and replaces the fossil fuel required by the steam injection boiler with the heat stored in the mobile thermal energy storage, while realizing the low carbon emission requirements of long-distance equipment transportation and oil extraction.

[0025] 5. The control room I of the present invention is equipped with doors on both sides for entering and exiting the control room. This structure facilitates personnel entry and exit during operation and makes maintenance convenient.

[0026] 6. The thermal storage zone III of this invention is towed by an independent mobile trailer to facilitate long-distance transportation and replacement when the stored heat is insufficient. That is, when the stored heat in thermal storage zone III cannot meet the needs of steam generation zone II and the stored heat in thermal storage zone III cannot be replenished in time, a new thermal storage zone III can be transported to the operating site and connected to another set of heat source inlets to avoid downtime. At the same time, an insulation layer is wrapped around the outer layer of thermal storage zone III to reduce heat loss. Thermal storage zone III can adopt single-tank molten salt thermal storage, double-tank molten salt thermal storage, or solid thermal storage technology, which has the advantages of high flexibility. Attached Figure Description

[0027] Appendix Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] Appendix Figure 2 This is a diagram showing the steam and water flow out of steam generation zone II.

[0029] Appendix Figure 3 This is the flow diagram of the heat source medium side of steam generation zone II.

[0030] Appendix Figure 4 This is a schematic diagram of a single-tank molten salt thermal storage structure.

[0031] Appendix Figure 5 This is a schematic diagram of the molten salt distribution ring structure.

[0032] Appendix Figure 6 This is a schematic diagram of the electric heater structure.

[0033] Appendix Figure 7 This is a schematic diagram of a dual-tank molten salt thermal storage structure.

[0034] Appendix Figure 8 This is a schematic diagram of a solid heat storage structure.

[0035] The components include: 1. Mobile trailer; 2. Trailer base plate; 3. Connecting and fixing device; 4. Door; 5. Water preheating device; 6. Steam generator; 7. Steam-water separator; 8. Circulating pump; 9. Electric heating / preheating device; 10. Preheating shut-off valve; 11. Molten salt inlet shut-off valve I; 12. Molten salt inlet shut-off valve II; 13. Heat source medium inlet I; 14. Heat source medium inlet II; 15. Insulation layer; 16. Molten salt pump; 17. Hot molten salt outlet; 18. Hot molten salt inlet; 19. Cold molten salt inlet; 20. Salt release valve; 21. Molten salt distribution ring; 22. Electric heater; 23. Long-shaft molten salt pump; 24. Solid heat storage material; 25. Axial flow fan; 26. Hot air outlet; 27. Cold air inlet; 28. Gate valve. Detailed Implementation

[0036] Example 1:

[0037] A mobile thermal storage and steam injection system comprises: two mobile trailers 1 and a set of trailer base plates 2. The two mobile trailers are mounted on the trailer base plates 2 and are respectively mounted at both ends of the trailer base plates. The adjacent trailer base plates are connected by a connecting and fixing device 3. A control room 1, a steam generation zone 2, and a thermal storage zone 3 are respectively installed on the mobile trailers. The control room 1 is the integrated control center of the steam generation zone 2 and the thermal storage zone 3. The control room 1 is equipped with a matching control operation and monitoring system. Doors 4 are installed on both sides of the control room 1 and the steam generation zone 2. The thermal storage zone 3 is covered with an insulation layer 15.

[0038] Example 2:

[0039] According to the mobile thermal storage steam injection system described in Embodiment 1, the steam generation zone II includes a feedwater preheating device 5, which is connected to a steam generation device 6, an electric heating / preheating device 9, and external feedwater. The steam generation device is connected to a steam-water separation device 7 via a preheating shut-off valve 10. The steam-water separation device is connected to the steam injection outlet. The electric heating / preheating device is connected to the steam generation device via a circulating pump 8.

[0040] Example 3:

[0041] According to the mobile thermal storage and steam injection system described in Example 1, the steam generation zone II has a heat source medium inlet I13 and a heat source medium inlet II14. The heat source medium inlet I and the heat source medium inlet II are respectively connected to the steam generation device through molten salt inlet shut-off valve I11 and molten salt inlet shut-off valve II12. The steam generation device is connected to the feedwater preheating device, and the feedwater preheating device is connected to the heat source medium outlet.

[0042] Example 4:

[0043] According to the mobile thermal storage steam injection system described in Example 1, when the thermal storage zone III adopts single-tank molten salt thermal storage, a molten salt pump 16 and a hot molten salt inlet 18 are respectively installed on the top of the thermal storage zone III, and a cold molten salt inlet 19 and a salt discharge valve 20 are respectively installed at its bottom. The molten salt pump is connected to the hot molten salt outlet 17. Both the hot molten salt inlet and the cold molten salt inlet are equipped with molten salt distribution rings 21. The molten salt distribution rings 21 have multiple sets of connecting pipes. When the thermal storage zone III adopts dual-tank molten salt thermal storage, an electric heater 22 should be installed at the bottom of the thermal storage zone III, and the suction port of the long-shaft molten salt pump 23 is located at the lower part of the thermal storage zone III.

[0044] Example 5:

[0045] According to the mobile thermal storage steam injection system described in Example 1, when the thermal storage zone III adopts solid thermal storage, the solid thermal storage material 24 is made of magnesium brick, granite, concrete, or composite phase change material. An axial flow fan 25 and a cold air inlet 27 are respectively installed on both sides of the bottom of the thermal storage zone III, and a hot air outlet 26 is installed above it. The cold air inlet and the hot air outlet are respectively connected to a gate valve 28.

[0046] Example 3:

[0047] According to the thermal storage and steam injection method of the mobile thermal storage and steam injection system described in Examples 1-2, the method includes the following steps:

[0048] Firstly, control room I serves as the integrated control center for steam generation zone II and heat storage zone III. Control room I is equipped with a supporting control and monitoring system to monitor the real-time parameters of steam generation zone II and heat storage zone III, control the flow rate of the heat transfer medium from heat storage zone III into steam generation zone II, and control the operating parameters of steam generation zone II. Control room I and steam generation zone II can be fixedly installed on the trailer floor of the same mobile trailer, or they can be fixedly installed on the trailer floors of two different mobile trailers, depending on the carrying capacity of the mobile trailers and the specifications and weight of the equipment in control room I and steam generation zone II. Steam generation zone II is towed by two trailers. In use, the mobile trailers are separated from their trailer bases, and the trailer bases of control room I and steam generation zone II are connected and fixed by a connecting and fixing device. Steam generation zone II consists of a feedwater preheating device, a steam generating device, and a steam-water separation device. When the heat storage medium in heat storage zone III is molten salt, an additional circulating pump, electric heating / preheating device, and preheating shut-off valve are required. Both the feedwater preheating device and the steam generating device are indirect heat exchangers. The feedwater preheating device has a heat source medium on one side and water on the other side, while the steam generating device has a heat source medium on one side and steam-water two-phase on the other side.

[0049] When the mobile thermal storage steam injection system is working, the heat source medium enters the steam generator and the feedwater preheating device in sequence. The water is first heated to a certain temperature by the feedwater preheating device, and then enters the steam generator to generate saturated steam. The steam enters the steam-water separator for separation.

[0050] When the heat storage medium in heat storage zone III is molten salt, because molten salt will solidify when the temperature is below 150-230℃, the water temperature in the feed water preheating device, steam generator and its equipment needs to be preheated before the heat source medium enters the steam generation system. The process is to close the preheating shut-off valve, turn on the circulating pump and the electric heating / preheating device, and heat the water to a certain temperature by circulating between the circulating pump, the electric heating / preheating device, the feed water preheating device and the steam generator. Only after the water temperature is heated to a certain temperature can the molten salt inlet shut-off valve I or the molten salt inlet shut-off valve II be opened so that the steam generation zone II can work normally.

[0051] When the heat storage medium in heat storage zone III is molten salt, if the temperature of the external feed water is lower than the freezing point of the molten salt, the circulating pump and the electric heating / preheating device can be turned on to raise the water temperature entering the feed water preheating device in order to avoid molten salt solidification.

[0052] Steam generation zone II has two heat source medium inlets I and II, as well as molten salt inlet shut-off valves I and II. When the mobile thermal storage steam injection system is working normally, it can enter from only one of the thermal storage medium inlets. The molten salt inlet shut-off valves corresponding to the working heat source medium inlet is opened, and the other set is closed.

[0053] (1) When the single-tank molten salt thermal storage technology is adopted in thermal storage zone III, the molten salt pump inlet should be located at the upper part of thermal storage zone III. During operation, hot molten salt is drawn from the upper part of thermal storage zone III and sent to the heat source medium inlet of steam generation zone II through the hot molten salt outlet. Hot molten salt can be replenished to thermal storage zone III through the hot molten salt inlet. Molten salt cooled by steam generation zone II enters thermal storage zone III through the cold molten salt inlet. A salt drain valve is installed at the bottom of thermal storage zone III. In case of an accident or during maintenance of thermal storage zone III, the salt drain valve can be opened to drain the hot molten salt from thermal storage zone III. Molten salt; both the hot molten salt inlet and the cold molten salt inlet should be equipped with molten salt distribution rings. The molten salt distribution rings consist of multiple sets of connecting pipes with small holes to ensure that the molten salt enters the heat storage zone III uniformly and at a low speed, so as to avoid damaging the temperature slope layer of the single-tank molten salt heat storage technology and ensure that the hot molten salt is always in the upper part of the heat storage zone III, and the cooled molten salt is located in the lower part of the heat storage zone III. Electric heaters can be installed at appropriate locations in the heat storage zone III to compensate for heat loss, or direct electric heating energy storage can be carried out when there is a small amount of hot molten salt in the heat storage zone III.

[0054] (2) When the thermal storage zone III adopts the dual-tank molten salt thermal storage technology, a long-shaft molten salt pump is installed at the top of thermal storage zone III and a salt discharge valve is installed at the bottom; the suction port of the long-shaft molten salt pump should be located at the bottom of thermal storage zone III to ensure that the maximum amount of molten salt can be used, and the hot molten salt outlet is sent to the heat source medium inlet of steam generation zone II; hot molten salt can be replenished to thermal storage zone III through the hot molten salt inlet; during operation, there are two molten salt thermal storage tanks on site, one full tank and one empty tank. The empty tank is used to hold the molten salt cooled by steam generation zone II; an electric heater should be installed at the bottom of thermal storage zone III to compensate for heat loss;

[0055] (3) When solid heat storage technology is used in heat storage zone III, the solid heat storage material can be magnesium brick, granite, concrete, or composite phase change material. The material should be stacked with certain gaps to allow air flow. An axial flow fan is installed at the bottom of heat storage zone III to drive the air to carry away the heat of the solid heat storage material and heat the air. When steam generation zone II is working, the gate valve needs to be opened so that hot air can flow out from the hot air outlet and the cold air after heat exchange flows into the heat storage zone from the cold air inlet to be reheated. Electric heaters should be reasonably arranged inside the solid heat storage material to heat the solid heat storage material during heat storage.

Claims

1. A mobile thermal energy storage and steam injection system, comprising: Two mobile trailers and a set of trailer base plates are characterized in that: the two mobile trailers are installed on the trailer base plates and are respectively installed at both ends of the trailer base plates, wherein adjacent trailer base plates are connected by a connecting and fixing device; each mobile trailer is equipped with a control room I, a steam generation zone II, and a heat storage zone III; the control room I is the integrated control center of the steam generation zone II and the heat storage zone III; the control room I is equipped with a matching control operation and monitoring system; doors are installed on both sides of the control room I and the steam generation zone II; and the heat storage zone III is covered with an insulation layer. The steam generation zone II includes a feedwater preheating device, which is connected to the steam generator, the electric heating / preheating device, and the external feedwater device. The steam generator is connected to a steam-water separator via a preheating shut-off valve, and the steam-water separator is connected to the steam injection outlet. The electric heating / preheating device is connected to the steam generator via a circulating pump. The steam generation zone II has a heat source medium inlet I and a heat source medium inlet II, which are connected to the steam generator via molten salt inlet shut-off valves I and II, respectively. The steam generator is connected to the feedwater preheating device, and the feedwater preheating device is connected to the heat source medium outlet. When the thermal storage zone III uses single-tank molten salt thermal storage, a molten salt pump and a hot molten salt inlet are installed on the top of the thermal storage zone III. At the bottom of thermal storage zone III, a cold molten salt inlet and a salt discharge valve are installed respectively. The molten salt pump is connected to the hot molten salt outlet. Both the hot molten salt inlet and the cold molten salt inlet are equipped with molten salt distribution rings. The molten salt distribution rings have multiple sets of connecting pipes. When thermal storage zone III adopts dual-tank molten salt heat storage, an electric heater is installed at the bottom of thermal storage zone III, and the suction port of the long-shaft molten salt pump is located at the lower part of thermal storage zone III. When thermal storage zone III adopts solid heat storage, the solid heat storage material is magnesium brick, granite, concrete, or composite phase change material. Axial flow fans and cold air inlets are installed on both sides of the bottom of thermal storage zone III, and hot air outlets are installed above them. The cold air inlets and the hot air outlets are respectively connected to gate valves.

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