Automatic liquid discharge and vacuum heat tracing system for shale oil and control method thereof

Abstract

This invention provides an automatic shale oil drainage and vacuum heat tracing system and its control method. The system includes a separator, an automatic drainage valve, a level gauge, and a protective casing. The separator is connected to the wellhead to separate the produced fluid into oil, gas, and water. The automatic drainage valve is connected to the separator and externally connected to the production operation command center. The command center adjusts the opening of the automatic drainage valve to drain the liquid from the separator. The level gauge is connected to the separator to measure the liquid level. The protective casing is located outside the separator and contains insulation material. A heat tracing space is formed between the protective casing and the level gauge. This invention improves work efficiency, reduces the labor intensity of employees, and ensures the automatic drainage system operates automatically.

Description

Technical Field

[0001] This invention relates to the field of shale oil automatic drainage system operation technology, and in particular to an automatic shale oil drainage and vacuum heat tracing system and its control method. Background Technology

[0002] Shale oil is characterized by high wax content and high pour point, resulting in a large demand for heat at the production site. Production conditions vary significantly during shale oil fracturing, trial production, trial injection, and changes in production procedures, making it difficult for the control system to adjust temperature accordingly. Due to the physical properties of shale oil, automatic drainage systems cannot automatically control the opening of drainage valves, requiring manual adjustments, leading to high labor intensity and low efficiency for employees. During production, temperature drops can easily cause inaccurate readings from separator level gauges. Separator level gauges primarily reflect the height of produced fluid within the separator; inaccurate readings hinder the assessment, prediction, and analysis of shale oil production, compromising safe and stable production. Furthermore, the automatic drainage valves cannot receive accurate data from the level gauges and cannot automatically adjust, requiring employees to manually adjust the valve opening based on experience, resulting in high labor intensity and potential safety hazards.

[0003] Publication No. CN101513117A discloses a heat tracing assembly comprising a heat tracing segment, an insulating sheath surrounding the heat tracing segment, and a plurality of spacers disposed between the heat tracing segment and the insulating sheath. Multiple corresponding channels are formed between the heat tracing segment and the insulating sheath, and between the plurality of spacers. The spacers may be part of the insulating sheath and / or the heat tracing segment, and may be integrally formed with the insulating sheath and / or the heat tracing segment, or may be formed separately and then connected to the insulating sheath and / or the heat tracing segment. This device does not meet the explosion-proof requirements of oil and gas production sites and cannot achieve automatic control.

[0004] Announcement No. CN108736107B discloses a heating module and a battery pack heating method and system. The heating module includes an energy storage unit, a first switching unit, a second switching unit, and a control unit. The energy storage unit, the first battery cell in the battery pack, and the first switching unit can form a first heating circuit; the energy storage unit, the second battery cell in the battery pack, and the second switching unit can form a second heating circuit. The control unit can control the first or second switching unit to sequentially connect the heating circuits of the battery cells with higher states of charge and the battery cells with lower states of charge in the first and second heating circuits, keeping the battery pack in a continuous discharging and charging state, and using the electrical energy generated during the continuous discharging and charging process to heat the battery pack. This heating system cannot meet the requirements of high heat demand and continuous high temperatures at oil and gas production sites.

[0005] Publication number CN105143621A describes an intelligent heating system, which generally includes: at least one heater element; optionally, at least one temperature sensor; a set of predetermined or predictable performance information for controlling the heating system; and optionally, an electronic control module (ECU) capable of storing and processing the performance information. The performance information can be stored as text, barcodes, data matrices, or radio frequency identification (RFID) tags. The intelligent heating system may also include a LIN bus or CAN bus capable of providing a communication path between at least two system components. This heating system only provides control functions and lacks a heat tracing device suitable for oil and gas production sites.

[0006] The existing technologies described above are significantly different from this invention. A search reveals no literature in the XY category, indicating that this invention is innovative. Since no solution exists in the existing technology to address the technical problem we seek to solve, we have invented a novel shale oil automatic drainage and vacuum heating system and its control method. Summary of the Invention

[0007] The purpose of this invention is to provide an automatic shale oil drainage and vacuum heat tracing system and its control method that can improve work efficiency and reduce the labor intensity of employees.

[0008] The objective of this invention can be achieved through the following technical measures: an automatic shale oil drainage and vacuum heat tracing system, comprising a separator, an automatic drainage valve, a level gauge, and a protective shell. The separator is connected to the wellhead to separate the produced fluid into oil, gas, and water. The automatic drainage valve is connected to the separator and externally connected to the production operation command center, which adjusts the opening of the automatic drainage valve to drain the liquid from the separator. The level gauge is connected to the separator to measure the liquid level inside the separator. The protective shell is located outside the separator and has insulation material inside. A heat tracing space is formed between the protective shell and the level gauge.

[0009] The objective of this invention can also be achieved through the following technical measures:

[0010] The shale oil automatic drainage and vacuum heating system also includes a remote transmission module, which is connected to the level gauge and transmits the current liquid level information measured by the level gauge to the production operation command center. The production operation command center adjusts the opening of the automatic drainage valve according to the received current liquid level information.

[0011] The production operation command center uses proportional control, integral control, and derivative control algorithms to perform logical PID control, which keeps the liquid level of the separator at the initial set level SV to ensure the efficient and safe operation of the separator.

[0012] The shale oil automatic drainage and vacuum heat tracing system also includes a U-shaped heat exchange coil and a connecting hose. The U-shaped heat exchange coil is installed in the heat tracing space and connected to the connecting hose. The heated conductive fluid enters the U-shaped heat exchange coil through the connecting hose, and the heat of the conductive fluid is radiated into the heat tracing space by vacuum.

[0013] The shale oil automatic drainage and vacuum heat tracing system also includes a heat tracing device, a power circulation pump and an electric heating rod. The connecting hose is connected to the heat tracing device, and the power circulation pump is connected to the heat tracing device. The heat tracing device contains a conductive liquid and has the electric heating rod inside. When the power circulation pump is started, it transfers the conductive liquid heated by the electric heating rod to the U-shaped heat exchange coil.

[0014] The shale oil automatic drainage and vacuum heat tracing system also includes a liquid level tank located above the heat tracing device. The liquid level tank is transparent to allow observation of the liquid level of the conductive fluid in the tank.

[0015] The shale oil automatic drainage and vacuum heating system also includes a liquid level tank cover, which is located above the liquid level tank to isolate the conductive liquid from air. The liquid level tank cover is equipped with a one-way vent. When the temperature of the conductive liquid rises, the pressure difference in the liquid level tank due to temperature difference can be discharged through the one-way vent to ensure the pressure balance in the liquid level tank.

[0016] The shale oil automatic drainage and vacuum heat tracing system also includes an explosion-proof control box, control buttons, and a control system. The explosion-proof control box is located outside the heat tracing device, the control buttons are located on the surface of the explosion-proof control box, and the control system is located inside the explosion-proof control box. The control buttons are connected to the control system. The preset temperature is manually set through the control buttons, and the control system controls the heating temperature of the electric heating rod to the preset temperature according to the temperature set by the control buttons.

[0017] The shale oil automatic drainage and vacuum heating system also includes a temperature sensor located in the conductive fluid. The temperature sensor detects the temperature of the conductive fluid in real time and transmits the collected temperature to the control system. When the required temperature is reached, the control system reduces the power of the electric heating rod.

[0018] The temperature sensor also transmits the detected temperature information Ti of the conductive fluid to the production operation command center. The production operation command center sets the ideal temperature T of the shale oil and the maximum allowable temperature difference a. The control system calculates the difference e between the ideal temperature T and the actual temperature Ti of the shale oil and determines whether the difference e reaches a preset percentage of the allowable temperature difference.

[0019] If the temperature difference e has reached the preset percentage of the allowable temperature difference, the production operation command center calls the PID control algorithm to obtain the temperature and current temperature over a time series, outputs an electric heating signal to the electric heating rod, and performs electric heating. After heating for n seconds, the temperature difference is calculated again to check whether it has reached the allowable temperature range for shale oil. If it has, the production operation command center calls the PID control algorithm to output a stop heating electric signal. After receiving the stop heating electric signal, the electric heating rod stops heating. If it has not reached the allowable temperature range, it continues heating.

[0020] If the difference e does not reach the preset percentage of the allowable temperature difference, the production operation command center starts a timer to continue monitoring the temperature and calculates the temperature difference every n seconds.

[0021] The objective of this invention can also be achieved through the following technical measures: a control method for an automatic shale oil drainage and vacuum heat tracing system, wherein the control method employs an automatic shale oil drainage and vacuum heat tracing system, including:

[0022] Step 1: The level gauge collects the current liquid level information of the separator and transmits it to the production operation command center;

[0023] Step 2: The production operation command center adjusts the opening of the automatic drain valve based on the received current liquid level information;

[0024] Step 3: Pump the conductive liquid in the heat tracing device into the U-shaped heat exchange coil, and the heat of the conductive liquid is radiated into the heat tracing space by vacuum.

[0025] Step 4: The temperature sensor in the conductive fluid detects the temperature of the conductive fluid and transmits the collected temperature to the control system. When the required temperature is reached, the control system reduces the power of the electric heating rod.

[0026] The objective of this invention can also be achieved through the following technical measures:

[0027] In step 2, the production operation command center uses proportional control, integral control, and derivative control algorithms to perform logical PID control, thereby maintaining the separator liquid level at the initial set liquid level SV to ensure the efficient and safe operation of the separator.

[0028] In step 2, when the liquid level in the separator is lower than 20% of the set value, it enters the low-discharge process of abnormal discharge. The production operation command center controls the automatic discharge valve to close, thereby ensuring that the liquid level rises.

[0029] When the liquid level in the separator rises to between 20% and 80% of the set value, the PID control process is initiated. The production operation command center controls the opening of the automatic drain valve to vary between 10% and 90% to ensure that the liquid level remains near the set value. The closer the liquid level is to the set value, the greater the change in the opening of the automatic drain valve, and vice versa.

[0030] When the liquid level in the separator suddenly rises to more than 80% of the set value, it enters the high-level liquid discharge process of abnormal liquid discharge; the production operation command center controls the opening of the automatic liquid discharge valve to increase.

[0031] In step 4, the temperature sensor also transmits the detected temperature information Ti of the conductive fluid to the production operation command center. The production operation command center sets the ideal temperature T of the shale oil and the maximum allowable temperature difference a. The control system calculates the difference e between the ideal temperature T and the actual temperature Ti of the shale oil and determines whether the difference e reaches a preset percentage of the allowable temperature difference.

[0032] In step 4, if the difference e has reached the preset percentage of the allowable temperature difference, the production operation command center calls the PID control algorithm to obtain the temperature and current temperature over a time series, outputs an electric heating signal to the electric heating rod, and performs electric heating. After heating for n seconds, the temperature difference is calculated again to check whether it has reached the allowable temperature range of shale oil. If it has, the production operation command center calls the PID control algorithm to output a stop heating electric signal. After receiving the stop heating electric signal, the electric heating rod stops heating. If it has not reached the allowable temperature range, heating continues.

[0033] If the difference e does not reach the preset percentage of the allowable temperature difference, the production operation command center starts a timer to continue monitoring the temperature and calculates the temperature difference every n seconds.

[0034] To ensure safe, green, low-carbon, and clean production, improve work efficiency, and reduce the labor intensity of employees, this invention innovatively develops a vacuum heating system for an automatic shale oil drainage system. The control method for the automatic shale oil drainage and vacuum heating system in this invention can be applied to the vacuum heating of the automatic drainage system during shale oil extraction, ensuring the automatic operation of the system. Compared with existing technologies, this invention achieves the following effects:

[0035] 1. The whole system adopts a skid-mounted design, and the control system and heat exchange device can be connected separately, which makes installation and maintenance convenient. In particular, the algorithm and control logic of the automatic drainage system are innovated in combination with the physical properties of shale oil with high wax content and high pour point.

[0036] 2. The temperature control system combines parameters such as ambient temperature, produced fluid temperature, and conductive fluid temperature to form a control unit mode, which can meet the flow rate changes under shale oil fracturing, trial production, and trial operation conditions;

[0037] 3. It fills the gaps in domestic shale oil automatic drainage system control technology and temperature control system technology, with excellent application results and good prospects for promotion. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the vacuum heating system of the shale oil automatic drainage system of the present invention;

[0039] Figure 2 This is a rear view of the vacuum heating system of the shale oil automatic drainage system of the present invention;

[0040] Figure 3 This is the automatic control logic diagram of the vacuum heating system of the shale oil automatic drainage system of the present invention;

[0041] Figure 4 This is the temperature control logic diagram of the vacuum heating system for the automatic drainage system of shale oil.

[0042] In the diagram: 1. Separator; 2. Level gauge; 3. Connecting pipe; 4. Remote transmission module; 5. Automatic drain valve; 6. Protective housing; 7. Insulation cotton; 8. Heat tracing space; 9. U-shaped heat exchange coil; 10. Connecting hose; 11. Heat tracing device; 12. Control valve; 13. Electric heating rod; 14. Level tank; 15. Conducting fluid; 16. Explosion-proof control box; 17. Control button ①; 18. Control button ②; 19. Control system; 20. Control element; 21. Control circuit; 22. Power circulation pump; 23. Level tank cover; 24. One-way breather; 25. Data display screen; 26. Temperature sensor. Detailed Implementation

[0043] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0044] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0045] The automatic shale oil drainage system vacuum heating system of this invention includes a separator, a level gauge, a connecting pipe, a remote transmission module, an automatic drainage valve, a protective shell, insulation cotton, a heating space, a U-shaped heat exchange coil, a connecting hose, a heating device, an electric heating rod, a level tank, a conductive fluid, an explosion-proof control box, control buttons, a control system, a power circulation pump, and a temperature sensor.

[0046] The separator is connected to the wellhead to separate oil, gas, and water in the produced fluid. A level gauge is connected to the separator via a connecting pipe to display the liquid level inside the separator. An automatic drain valve is connected to the separator, and a remote transmission module is connected to the level gauge to transmit the current liquid level information measured by the level gauge to the production operation command center. Based on the received liquid level information, the production operation command center, to adapt to the requirements of field conditions and ensure data stability, uses a wired transmission method to adjust the opening of the automatic drain valve to drain the liquid from the separator.

[0047] The protective outer shell, made of stainless steel, is located outside the separator and connecting pipe. Insulation cotton is installed inside the protective shell, creating a heat tracing space between the insulation cotton and the protective shell. A U-shaped heat exchange coil is installed within this heat tracing space and connected to the heat tracing device via a connecting hose. A power circulation pump is connected to the heat tracing device, which contains a conductive fluid and an internal electric heating rod. When the power circulation pump starts, it transfers the conductive fluid, heated by the electric heating rod, to the U-shaped heat exchange coil. At this time, the U-shaped heat exchange coil is filled with high-temperature conductive fluid, and heat is radiated into the heat tracing space through a vacuum.

[0048] A transparent water tank is installed above the heat tracing device to observe the level of the conductive fluid. An explosion-proof control box is located on the outside of the device, with control buttons on its surface and a control system inside. The control buttons allow for manual setting of the preset temperature, which is then controlled by the control system to maintain the heating temperature of the electric heating rod at the preset temperature. A temperature sensor is located in the conductive fluid, monitoring its temperature in real time and transmitting this data to the control system. When the desired temperature is reached, the control system reduces the power of the electric heating rod.

[0049] The technical advantages of this invention are as follows:

[0050] 1. The combination of U-shaped heat exchange coils, connecting hoses, heat tracing devices, electric heating rods and other devices can provide a large amount of heat. The use of protective shells and insulation cotton to form a vacuum heat tracing space can not only keep the heat but also avoid the impact of low ambient temperature on the heat exchange temperature.

[0051] 2. Intelligent control, including data acquisition, remote transmission, control, and feedback, is achieved through the combined use of temperature sensors, data transmission modules, and control systems.

[0052] 3. Based on the physical properties of shale oil, three algorithms—proportional control, integral control, and derivative control—are optimized for the automatic control drainage system. This algorithm can realize various operating conditions in shale oil production.

[0053] 4. Combining ideal temperature and maximum allowable temperature difference, an innovative PID control algorithm for the production operation command center control system was developed, which can automatically perform temperature compensation based on changes in parameters such as ambient temperature, liquid production, and oil-gas ratio.

[0054] like Figure 1 and Figure 2 As shown, during shale oil production, as the pressure and temperature decrease, coupled with the characteristics of high wax content and high pour point, the produced fluid is depressurized from the wellhead and enters the separator 1 for oil, gas and water separation. The level gauge 2 is connected to the separator via a connecting pipe 3 using bolts, which can display the liquid level height inside the separator. The level gauge is equipped with a remote transmission module 4, which can realize remote observation at the production operation command center. It can also be linked with the automatic drain valve 5 on site through a logic algorithm to realize automatic adjustment of the opening of the automatic drain valve by a fixed liquid level, thereby achieving automatic production.

[0055] In practical applications, as the temperature of the shale oil produced fluid decreases, wax will solidify in the connecting pipe and level gauge, making it impossible to accurately display the separator level and causing the automatic drainage device to fail to operate automatically. The device has a protective outer shell 6 made of stainless steel on the outside of the level gauge and connecting pipe. This shell mainly serves to create a heat tracing space and protect the heat exchange coil. The protective shell is filled with insulation cotton 7, which mainly serves to isolate the external ambient temperature and protect the temperature of the heat tracing space. At this time, a heat tracing space 8 is formed between the insulation cotton and the outer shell of the level gauge. A U-shaped heat exchange coil 9 is installed inside the heat tracing space. The heat exchange coil has inlet and outlet, which are connected to the inlet and outlet of the heat tracing device 11 by connecting hoses 10 through the threaded connection of control valves 12. The heat tracing device has an electric heating rod 13 inside, and a level water tank 14 is set above it. The level water tank has a transparent design so that the level of the conduction fluid 15 can be observed. A power circulation pump 21 is also provided to transport the heated conduction fluid to the U-shaped heat exchange coil. An explosion-proof control box 16 is set on the outside. The surface of the box has control buttons ①17 and ②18. Inside is a control system 19, which consists of control elements 20 and control circuits 22.

[0056] Example 1:

[0057] This invention provides a heat tracing system for an automatic shale oil drainage system. In use, the level gauge 2 is fixed to the connecting pipe 3 of the separator 1 by bolts. After establishing a linkage logic between the remote module 4 and the automatic drainage valve 5, a protective shell 6 is installed on the outside of the level gauge, and insulation cotton 7 is laid inside the protective shell. At this time, a heat tracing space 8 exists between the insulation cotton and the level gauge shell. The U-shaped heat exchange coil 9 is installed in the heat tracing space and connected to the heat tracing device 11 through the connecting hose 10. After connecting the heating device to the power supply, press the control button ①17 on the explosion-proof control box 16. At this time, the electric heating rod 13 heats the conductive liquid 15. After heating to the operating temperature, press the control button ②18 on the explosion-proof control box. At this time, the power circulation pump 22 is started. The power circulation pump delivers the heated conductive liquid to the U-shaped heat exchange coil through the connecting hose. At this time, the U-shaped heat exchange coil is filled with high-temperature conductive liquid. The heat is radiated into the heating space by vacuum. The temperature in this space continues to rise. With the function of insulation cotton and protective shell, the temperature will not be dissipated to the outside and will not be affected by the ambient temperature. The high temperature will radiate to the level gauge, connecting pipe and automatic drain valve that need to be heated. The temperature of the shale oil produced in the above equipment and facilities will be raised. After the temperature is raised above the freezing point temperature, the automatic drain system can be guaranteed to operate normally, ensuring the effective connection between the level gauge and the separator. The level of the separator can be displayed in real time, ensuring safe, stable, green and low-carbon production.

[0058] Example 2:

[0059] During operation, the system can achieve real-time replenishment of the conductive fluid. A liquid level tank 14 is installed above the heat tracing device 11. The liquid level tank has a semi-transparent design and uses green conductive fluid. The liquid level of the conductive fluid can be seen directly on the liquid level tank. Since the conductive fluid is connected to the heat tracing device, when the conductive fluid in the heat tracing device is insufficient due to evaporation, loss, or other reasons, the conductive fluid in the liquid level tank will be replenished in real time. By observing the liquid level in the liquid level tank, the loss of conductive fluid can be known. A liquid level tank cover 23 is also installed above the liquid level tank to isolate the conductive fluid from contact with air. A one-way vent 24 is provided on the liquid level tank cover. When the temperature of the conductive fluid rises, the pressure difference in the liquid level tank due to temperature difference can be discharged through the vent to ensure the pressure balance in the liquid level tank.

[0060] Example 3:

[0061] During the operation of this system, such as Figure 3 As shown, the initial set liquid level of the separator is SV. The sensor on the level gauge transmits the current liquid level of the separator to the production operation command center. Once the system is put into operation, the control algorithm samples the state value of the controlled object at regular intervals. This algorithm mainly consists of three parts: proportional control, integral control, and derivative control.

[0062] (1) Proportional control POUT

[0063] By calculating the sampled value X k The difference between the current deviation E and the initial set liquid level SV is obtained. k ,

[0064] Therefore, it can be based on E k The magnitude of the value adjusts the electrical signal OUT output by the liquid level sensor. The strength of the output signal is proportional to the magnitude of the current deviation, i.e., POUT = (Kp * Ek) + Out0.

[0065] Where Kp is generally called the proportional coefficient, which can be understood as an amplifier (or attenuator) in hardware. Appropriately selecting Kp will amplify or reduce the current error value Ek by a certain gain, so as to improve the response speed of the control algorithm.

[0066] Out0 is a constant whose purpose is to ensure that the output signal is not 0 when Ek is 0, so that the controller output signal OUT is not 0 when the current value is equal to the set value, and the system is in an uncontrolled state without a control signal.

[0067] (2) Integral control Iout

[0068] The algebraic sum of the deviation values ​​is obtained as S. k Right now:

[0069] Sk=E1+E2+E3+…………+Ek-2+Ek-1+Ek,

[0070] This allows for a comprehensive evaluation of the past control performance of the control algorithm, and the correction of the current output control signal OUT to ensure that the controlled object reaches the initial set value as quickly as possible within a short period of time. Therefore, the mathematical model of integral control based on Sk to adjust the output signal is: Iout = (Kp * S k )+out0

[0071] (3) Differential control D out

[0072] The difference D between the two most recent deviations k =E k -E k-1 The state change trend of the controlled object from the last sampling to the current sampling time is considered. This trend is likely to continue to some extent into the next sampling time point. Therefore, the output signal OUT can be adjusted based on this trend (the value of Dk) to achieve the purpose of advance control. The algorithm for adjusting the controller output signal using Dk can be expressed mathematically as Dout = (Kp * Dk) k )+out0.

[0073] Therefore, the final output electrical signal is PIDout = Kp(E k +S k +D k After the separator is subjected to logic PID control, the separator liquid level needs to be maintained at the initial set liquid level SV to ensure the efficient and safe operation of the separator.

[0074] 1) When the liquid level is 20% lower than the set value, the system is forced to enter the low-discharge process of abnormal discharge. In this process, the automatic discharge valve is closed to ensure that the liquid level rises.

[0075] 2) When the liquid level rises to between 20% and 80% of the set value, the system automatically enters the PID control process, and the opening of the automatic drain valve changes between 10% and 90% to ensure that the liquid level is kept near the set value. The closer the liquid level is to the set value, the greater the change in the opening of the automatic drain valve, and vice versa.

[0076] 3) When the liquid level suddenly rises to more than 80% of the set value, the system is forced to enter the abnormal high-level drainage process. In this process, the opening of the automatic drainage valve increases.

[0077] Example 4:

[0078] During operation, the system can adjust the temperature. There is a temperature control button on the explosion-proof control box, which can be adjusted according to the working conditions and the ambient temperature. To increase the temperature, rotate the control button ① clockwise. The temperature change will be displayed on the data screen 25. After adjusting to the required temperature, gently lift the control button ① to confirm the temperature. At this time, the control element 20 will increase the power of the electric heating rod 13 through the control circuit 21. After the power of the electric heating rod is increased, it outputs high temperature to increase the temperature of the conductive fluid. The temperature sensor 26 detects the temperature of the conductive fluid in real time. When the required temperature is reached, the control element will reduce the power of the electric heating rod through the control circuit. The set temperature can be controlled by the cooperation of the control element and the control circuit to achieve the purpose of temperature adjustment.

[0079] Specifically, such as Figure 4 As shown, the ideal temperature T and the maximum allowable temperature difference a for shale oil are set in the production operation command center. The temperature of the conductive fluid is measured using a thermometer with remote function, and the data is transmitted to the control system to calculate the difference e between the ideal temperature T and the actual temperature Ti of the shale oil. Then, it is determined whether this difference reaches 80% of the allowable temperature difference.

[0080] If the temperature difference reaches 80% of the allowable temperature difference, the PID control algorithm of the production operation command center is invoked to obtain the temperature over a time series and the current temperature, and an electrical signal is output. The electric heating rod receives this signal and starts the corresponding heating program. After heating for n seconds, the temperature difference is recalculated to check if it has reached the allowable temperature range for shale oil. If it has, the PID control algorithm of the heating automatic control module is invoked to output a stop heating electrical signal. The electric heating rod receives this signal and interrupts the heating program. If the temperature has not reached the allowable range, heating continues.

[0081] If the temperature difference does not reach 80% of the allowable temperature difference, the timer will be started because the production operation command center is equipped with a start timer to continue monitoring the temperature and calculate the temperature difference every n seconds.

[0082] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0083] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. An automatic shale oil drainage and vacuum heating system, characterized in that, The shale oil automatic drainage and vacuum heating system includes a separator, an automatic drainage valve, a level gauge, and a protective shell. The separator is connected to the wellhead to separate the produced fluid into oil, gas, and water. The automatic drainage valve is connected to the separator and externally connected to the production operation command center. The production operation command center adjusts the opening of the automatic drainage valve to drain the liquid in the separator. The level gauge is connected to the separator to measure the liquid level inside the separator. The protective shell is located on the outside of the separator and is equipped with insulation material inside. A heating space is formed between the protective shell and the level gauge.

2. The shale oil automatic drainage and vacuum heat tracing system according to claim 1, characterized in that, The shale oil automatic drainage and vacuum heating system also includes a remote transmission module, which is connected to the level gauge and transmits the current liquid level information measured by the level gauge to the production operation command center. The production operation command center adjusts the opening of the automatic drainage valve according to the received current liquid level information.

3. The shale oil automatic drainage and vacuum heating system according to claim 2, characterized in that, The production operation command center uses proportional control, integral control, and derivative control algorithms to perform logical PID control, which keeps the liquid level of the separator at the initial set level SV to ensure the efficient and safe operation of the separator.

4. The shale oil automatic drainage and vacuum heat tracing system according to claim 1, characterized in that, The shale oil automatic drainage and vacuum heat tracing system also includes a U-shaped heat exchange coil and a connecting hose. The U-shaped heat exchange coil is installed in the heat tracing space and connected to the connecting hose. The heated conductive fluid enters the U-shaped heat exchange coil through the connecting hose, and the heat of the conductive fluid is radiated into the heat tracing space by vacuum.

5. The shale oil automatic drainage and vacuum heat tracing system according to claim 4, characterized in that, The shale oil automatic drainage and vacuum heat tracing system also includes a heat tracing device, a power circulation pump and an electric heating rod. The connecting hose is connected to the heat tracing device, and the power circulation pump is connected to the heat tracing device. The heat tracing device contains a conductive liquid and has the electric heating rod inside. When the power circulation pump is started, it transfers the conductive liquid heated by the electric heating rod to the U-shaped heat exchange coil.

6. The shale oil automatic drainage and vacuum heat tracing system according to claim 5, characterized in that, The shale oil automatic drainage and vacuum heat tracing system also includes a liquid level tank located above the heat tracing device. The liquid level tank is transparent to allow observation of the liquid level of the conductive fluid in the tank.

7. The shale oil automatic drainage and vacuum heat tracing system according to claim 6, characterized in that, The shale oil automatic drainage and vacuum heating system also includes a liquid level tank cover, which is located above the liquid level tank to isolate the conductive liquid from air. The liquid level tank cover is equipped with a one-way vent. When the temperature of the conductive liquid rises, the pressure difference in the liquid level tank due to temperature difference can be discharged through the one-way vent to ensure the pressure balance in the liquid level tank.

8. The shale oil automatic drainage and vacuum heat tracing system according to claim 5, characterized in that, The shale oil automatic drainage and vacuum heat tracing system also includes an explosion-proof control box, control buttons, and a control system. The explosion-proof control box is located outside the heat tracing device, the control buttons are located on the surface of the explosion-proof control box, and the control system is located inside the explosion-proof control box. The control buttons are connected to the control system. The preset temperature is manually set through the control buttons, and the control system controls the heating temperature of the electric heating rod to the preset temperature according to the temperature set by the control buttons.

9. The shale oil automatic drainage and vacuum heat tracing system according to claim 8, characterized in that, The shale oil automatic drainage and vacuum heating system also includes a temperature sensor located in the conductive fluid. The temperature sensor detects the temperature of the conductive fluid in real time and transmits the collected temperature to the control system. When the required temperature is reached, the control system reduces the power of the electric heating rod.

10. The shale oil automatic drainage and vacuum heat tracing system according to claim 9, characterized in that, The temperature sensor also transmits the detected temperature information Ti of the conductive fluid to the production operation command center. The production operation command center sets the ideal temperature T of the shale oil and the maximum allowable temperature difference a. The control system calculates the difference e between the ideal temperature T and the actual temperature Ti of the shale oil and determines whether the difference e reaches a preset percentage of the allowable temperature difference.

11. The shale oil automatic drainage and vacuum heat tracing system according to claim 10, characterized in that, If the temperature difference e has reached the preset percentage of the allowable temperature difference, the production operation command center calls the PID control algorithm to obtain the temperature and current temperature over a time series, outputs an electric heating signal to the electric heating rod, and performs electric heating. After heating for n seconds, the temperature difference is calculated again to check whether it has reached the allowable temperature range for shale oil. If it has, the production operation command center calls the PID control algorithm to output a stop heating electric signal. After receiving the stop heating electric signal, the electric heating rod stops heating. If it has not reached the allowable temperature range, it continues heating.

12. The shale oil automatic drainage and vacuum heat tracing system according to claim 10, characterized in that, If the difference e does not reach the preset percentage of the allowable temperature difference, the production operation command center starts a timer to continue monitoring the temperature and calculates the temperature difference every n seconds.

13. A control method for an automatic shale oil drainage and vacuum heat tracing system, characterized in that, The control method for the automatic shale oil drainage and vacuum heat tracing system adopts the automatic shale oil drainage and vacuum heat tracing system described in claim 1, including: Step 1: The level gauge collects the current liquid level information of the separator and transmits it to the production operation command center; Step 2: The production operation command center adjusts the opening of the automatic drain valve based on the received current liquid level information; Step 3: Pump the conductive liquid in the heat tracing device into the U-shaped heat exchange coil, and the heat of the conductive liquid is radiated into the heat tracing space by vacuum. Step 4: The temperature sensor in the conductive fluid detects the temperature of the conductive fluid and transmits the collected temperature to the control system. When the required temperature is reached, the control system reduces the power of the electric heating rod.

14. The control method for the shale oil automatic drainage and vacuum heat tracing system according to claim 13, characterized in that, In step 2, the production operation command center uses proportional control, integral control, and derivative control algorithms to perform logical PID control, thereby maintaining the separator liquid level at the initial set liquid level SV to ensure the efficient and safe operation of the separator.

15. The control method for the shale oil automatic drainage and vacuum heat tracing system according to claim 14, characterized in that, In step 2, when the liquid level in the separator is lower than 20% of the set value, it enters the low-discharge process of abnormal discharge. The production operation command center controls the automatic discharge valve to close, thereby ensuring that the liquid level rises. When the liquid level in the separator rises to between 20% and 80% of the set value, the PID control process is initiated. The production operation command center controls the opening of the automatic drain valve to vary between 10% and 90% to ensure that the liquid level remains near the set value. The closer the liquid level is to the set value, the greater the change in the opening of the automatic drain valve, and vice versa. When the liquid level in the separator suddenly rises to more than 80% of the set value, it enters the high-level liquid discharge process for abnormal liquid discharge. The production operation command center controls the opening of the automatic drain valve to increase.

16. The control method for the shale oil automatic drainage and vacuum heat tracing system according to claim 13, characterized in that, In step 4, the temperature sensor also transmits the detected temperature information Ti of the conductive fluid to the production operation command center. The production operation command center sets the ideal temperature T of the shale oil and the maximum allowable temperature difference a. The control system calculates the difference e between the ideal temperature T and the actual temperature Ti of the shale oil and determines whether the difference e reaches a preset percentage of the allowable temperature difference.

17. The control method for the shale oil automatic drainage and vacuum heat tracing system according to claim 16, characterized in that, In step 4, if the difference e has reached the preset percentage of the allowable temperature difference, the production operation command center calls the PID control algorithm to obtain the temperature and current temperature over a time series, outputs an electric heating signal to the electric heating rod, and performs electric heating. After heating for n seconds, the temperature difference is calculated again to check whether it has reached the allowable temperature range of shale oil. If it has, the production operation command center calls the PID control algorithm to output a stop heating electric signal. After receiving the stop heating electric signal, the electric heating rod stops heating. If it has not reached the allowable temperature range, heating continues. If the difference e does not reach the preset percentage of the allowable temperature difference, the production operation command center starts a timer to continue monitoring the temperature and calculates the temperature difference every n seconds.

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