Shale oil well under-pressure paraffin control and plug removal method and system based on temperature compensation

Abstract

The invention discloses a shale oil well under-pressure paraffin control and plug removal method and system based on temperature compensation. The problems that an existing paraffin removal and control method is large in workload, high in cost and incapable of being implemented due to high wellhead pressure are mainly solved. The method is characterized by comprising the following steps: step 1, collecting the tripping-in depth H of the electric submersible pump of the oil well, the temperature Tdown at the depth, the original wellhead temperature Tup and the paraffin precipitation temperature Tout; 2, judging whether a heating pipe cable is put in or not: if the wellhead temperature Tup is greater than or equal to Tout, not putting the heating pipe cable in; if the wellhead temperature is Tuplt; if Tout is greater than Tout, a heating pipe cable is put down; step 3, calculating the tripping-in depth L of the heating pipe cable; 4, the power P1 needed by the heating system for well fluid temperature compensation is calculated; and 5, starting and stopping of heating and heating power are controlled according to the oil well operation working conditions. The method solves the problem of wellbore blockage caused by high wax content of the shale oil well, and reduces the paraffin removal workload and cost.

Description

Technical Field

[0001] The invention relates to the field of oil field wax removal and prevention, and in particular to a shale oil well under-pressure wax prevention and blockage removal method and system based on temperature compensation. Background Art

[0002] Efficient wax cleaning and prevention technology is an effective technical measure to ensure the normal production of oil wells with high wax content. At present, there are three main methods of wax cleaning and prevention: one is mechanical wax cleaning, which uses wax cleaning tools to go into the well, scrape the wax on the oil pipe wall, and bring the wax to the ground by liquid flow. This method requires stopping the well for operation, and the process is cumbersome and the work intensity is high; the second is thermal wax cleaning and prevention, which uses thermal energy to increase the temperature of the wellbore fluid to achieve wax cleaning and prevention. This method is effective, but is affected by the wax cleaning cycle, has poor adaptability and high cost under high wax content well fluid conditions; the third is chemical wax cleaning and prevention, which uses chemical agents to clean and prevent wax in oil wells. It is a technology that is currently widely used in oil fields. Frequent addition of drugs in high wax content well fluids is affected by casing pressure, and there are difficulties in adding drugs, especially in shale oil wells with high wellhead pressure, which cannot be implemented and there are certain safety hazards. Summary of the invention

[0003] In order to overcome the problems of existing wax cleaning and prevention methods such as large workload, high cost, and inability to implement due to high wellhead pressure, the present invention provides a shale oil well pressure-based wax prevention and unblocking method and system, which solves the problem of wellbore blockage caused by high wax content in shale oil wells and reduces the workload and cost of wax cleaning.

[0004] The technical solution of the present invention is: a method for preventing wax plugging in shale oil wells under pressure based on temperature compensation, comprising the following steps:

[0005] Step 1: Collect the depth H of the oil well submersible pump and the temperature T at that depth down , original wellhead temperature T up and wax precipitation temperature T out ;

[0006] Step 2: Determine whether to lower the heating cable: If the wellhead temperature T up ≥T out , without inserting the heating pipe cable; if the wellhead temperature T up <T out , then put the heating pipe cable in;

[0007] Step 3, calculating the insertion depth L of the heating pipe cable;

[0008] Step 4: Calculate the power P required by the heating system for well fluid temperature compensation 1 ;

[0009] Step 5: Control the start and stop of heating and the heating power according to the operating conditions of the oil well.

[0010] Further, the step 3 comprises:

[0011] Step 3.1: Estimate the temperature drop gradient from the pump depth to the wellhead:

[0012] γ=(T down -T up ) / H,

[0013] Where: T down is the temperature at the depth where the submersible pump is located, °C; T up is the temperature at the wellhead, °C; H is the depth of the submersible pump, m;

[0014] Step 3.2: Determine the initial depth of the heating tube cable:

[0015] l=100(T aim -T up ) / γ,

[0016] Where: Taim is the expected target temperature at the wellhead, °C.

[0017] Step 3.3: Heating tube cable insertion depth:

[0018] L=l+Δl,

[0019] Where: Δl is the increased heating depth, which is the integer of the heating pipe cable insertion depth L.

[0020] Further, the step 4 comprises:

[0021] Step 4.1: Calculate the heat Q released by the water component in the daily oil well fluid from the depth L to the wellhead water , kW·h,

[0022] Q water =C water V water ρ water (T aim -T up ) / (3.6×10 6 ),

[0023] Where: C water is the specific heat capacity of water, kg·℃; V water is the volume of water produced per day, m 3 / d;ρ water is the density of water, kg / m 3 ;

[0024] Step 4.2: Calculate the heat Q released by the oil component in the daily production of the oil well from the depth L to the wellhead oil , kW·h,

[0025] Qoil =C oil V oil ρ oil (T aim -T up ) / (3.6×10 6 );

[0026] Where: C water is the specific heat capacity of oil, kg·℃; V oil is the volume of oil produced per day, m 3 / d;ρ oil is the density of oil, kg / m 3 .

[0027] Step 4.3: Calculate the power P required by the heating system for well fluid temperature compensation 1 ,kW:P 1 =(Q wate +Q oil ) / twenty four.

[0028] Furthermore, the step 4 further comprises:

[0029] Step 4.4: Calculate the required power P of the heating system for well fluid temperature compensation 1 Calculate the heating pipe compensation power P based on the heating pipe cable insertion depth L 2 , W / m:

[0030] P 2 =P 1 / L.

[0031] Further, the step 5 comprises:

[0032] Step 5.1: Initial heating power is set to 20%-30% of the rated power, and gradually increased until the temperature at a certain power reaches the wellhead target temperature T aim , then run at this temperature;

[0033] Step 5.2: During the stable operation of the oil well, when the wellhead temperature is greater than the wellhead target temperature T aim , stop heating, below the wellhead target temperature T aim , heated by startup;

[0034] Step 5.3, wax blockage condition, continuous heating.

[0035] Further, the step 5.1 comprises:

[0036] Step 5.1.1: The initial heating power is set to 20%-30% of the rated power, and the power is gradually increased by 20% of the rated power per hour to 80% of the rated power. During the adjustment period, if the temperature reaches the target temperature T at a certain power aimStop heating when

[0037] Step 5.1.2: Run at 80% of rated power for 3 hours without reaching the target wellhead temperature T aim , and then increase the power by 10% of the rated power until the wellhead target temperature T is reached. aim .

[0038] A shale oil well pressurized wax prevention and plugging removal system based on temperature compensation, comprising a ground power supply unit, a heating pipe cable running unit, and a well fluid temperature control unit, wherein the ground power supply unit is connected to the heating pipe cable, the upper end of the heating pipe cable is connected to the heating pipe cable running unit, the lower end is connected to a submersible electric pump, and the lower end of the submersible electric pump is connected to a downhole sensor; the well fluid temperature control unit comprises an oil pressure and temperature monitoring device, a casing pressure and temperature monitoring device, and the temperature monitoring device, the casing pressure and temperature monitoring device are connected to a main vehicle control room in the heating pipe cable running unit.

[0039] Furthermore, the ground power supply unit includes a main distribution box, one end of which is connected to the high-voltage transmission line through a step-down transformer, and the other end is connected to a primary power cable. The primary power cable is connected to a secondary power cable through a medium-frequency boost controller, and the secondary power cable is connected to the heating tube cable through a wiring cavity.

[0040] Furthermore, the heating tube and cable lowering unit comprises a main vehicle and an auxiliary vehicle. The main vehicle is provided with a main vehicle control room and a heating tube and cable drum, and the auxiliary vehicle is provided with an auxiliary vehicle control room and a support frame. The heating tube and cable are controlled by the main vehicle control room and lowered into the well along the heating tube and cable drum; the blowout preventer box and the blowout preventer are hoisted to the wellhead by a hook on the support frame.

[0041] Furthermore, the heating tube cable comprises a power transmission core wire, an insulating layer is arranged outside the power transmission core wire, and a duplex stainless steel sheath is arranged outside the insulating layer.

[0042] The present invention has the following beneficial effects: Due to the adoption of the above scheme, the wax prevention and plugging removal system can lower the heating cable into the oil pipe without stopping the well under pressure, realize the transmission of electric energy and convert the electric energy into heat energy at the same time, increase the temperature of crude oil, reduce the viscosity and improve the fluidity. At the same time, the heating operation control method based on temperature compensation forms a dynamic connection between the operating power and the well fluid by combining the oil well data with the control system, and can realize the automatic heating system with different changes in liquid production, adapt to the production needs of shale oil wells with large fluctuations in liquid production, solve the problem of wellbore blockage caused by high wax content in shale oil wells, reduce the workload and cost of wax removal, and have a high system safety factor and stable and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of the present invention;

[0044] Figure 2It is a schematic diagram of the structure of the present invention;

[0045] Figure 3 is a cross-sectional view of the heating tube cable in the present invention;

[0046] Figure 4 It is a schematic diagram of the heating tube cable running unit in the present invention.

[0047] In the figure, 100-high-voltage transmission line, 101-step-down transformer, 102-main distribution box, 103-primary power cable, 104-medium frequency boost controller, 105-secondary power cable, 106-wiring chamber, 107-suspension and blowout prevention device, 201-oil pipe gate valve, 202-oil pressure and temperature monitoring device, 203-casing gate valve, 204-casing pressure and temperature monitoring device, 301-heating pipe cable, 302-transmission core wire, 303-insulation layer, 304-duplex stainless steel sheath, 401-submersible electric pump, 402-downhole sensor, 501-main vehicle, 502-main vehicle control room, 503-pipe rack, 504-heating pipe and cable drum, 505-auxiliary vehicle, 506-auxiliary vehicle control room, 507-support frame, 508-hook, 509-gooseneck pipe, 510-traction chain, 511-injection head assembly, 512-blowout preventer box, 513-blowout preventer. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with the accompanying drawings:

[0049] Depend on Figure 1 As shown, a method for preventing wax plugging in shale oil wells under pressure based on temperature compensation comprises the following steps:

[0050] Step 1: Collect the depth H of the oil well submersible pump and the temperature T at that depth down , original wellhead temperature T up and wax precipitation temperature T out .

[0051] Step 2: Based on the parameters in step 1, determine whether it is necessary to run a heating cable: If the wellhead temperature T up ≥T out , the heating pipe cable may not be lowered; if the wellhead temperature T up <T out , a heating pipe cable should be lowered to prevent the wax in the crude oil from precipitating and blocking the oil pipe.

[0052] Step 3: Calculate the depth L of the heating tube cable according to the parameters in step 1, specifically:

[0053] Step 3.1, estimate the temperature drop gradient γ from the pump depth to the wellhead in the wellbore,

[0054] γ=(T down -Tup ) / H,

[0055] Where: T down is the temperature at the depth where the submersible pump is located, °C; T up is the temperature at the wellhead, °C; H is the depth of the submersible pump, m;

[0056] Step 3.2: Determine the initial insertion depth of the heating tube cable, m:

[0057] l=100(T aim -T up ) / γ,

[0058] Where: Taim is the expected target temperature at the wellhead, °C.

[0059] Step 3.3: Calculate the depth L of the heating cable, taking into account the influence of the temperature drop gradient in the wellbore, the loss of heating depth due to the bending of the heating cable, and the influence of the ambient temperature on the wellhead temperature, and round the overall length:

[0060] L=l+Δl,

[0061] Where: Δl is the increased heating depth, which is the integer of the heating pipe cable insertion depth L.

[0062] Step 4: Calculate the power P required by the heating system for well fluid temperature compensation based on the parameters in steps 1 and 3. 1 , specifically:

[0063] Step 4.1: Calculate the heat Q released by the water component in the daily oil well production from the depth L to the wellhead water , kW·h,

[0064] Q water =C water V water ρ water (T aim -T up ) / (3.6×10 6 ),

[0065] Where: C water is the specific heat capacity of water, kg·℃; V water is the volume of water produced per day, m 3 / d;ρ water is the density of water, kg / m 3 ;

[0066] Step 4.2: Calculate the heat Q released by the oil component in the daily production of the oil well from the depth L to the wellhead oil , kW·h,

[0067] Q oil=C oil V oil ρ oil (T aim -T up ) / (3.6×10 6 );

[0068] Where: C water is the specific heat capacity of oil, kg·℃; V oil is the volume of oil produced per day, m 3 / d;ρ oil is the density of oil, kg / m 3 .

[0069] Step 4.3: Calculate the power P required by the heating system for well fluid temperature compensation 1 ,kW:P 1 =(Q wate +Q oil ) / twenty four.

[0070] Step 4.4: Calculate the required power P of the heating system for well fluid temperature compensation 1 Calculate the heating pipe compensation power P based on the heating pipe cable insertion depth L 2 , W / m:

[0071] P 2 =P 1 / L.

[0072] Step 5: Control the start and stop of heating and the heating power according to the operating conditions of the oil well, which specifically includes three operating conditions:

[0073] Step 5.1: Heating at the initial stage of production.

[0074] Step 5.1.1: The initial heating power is set to 20%-30% of the rated power, and the power is gradually increased by 20% of the rated power per hour to 80% of the rated power. During the adjustment period, if the temperature reaches the target temperature T at a certain power aim When , it runs at this temperature;

[0075] Step 5.1.2: If the target wellhead temperature T is not reached after running at 80% of the rated power for 3 hours aim , and then increase the power by 10% of the rated power until the wellhead target temperature T is reached. aim .

[0076] Step 5.2: During the stable operation of the oil well, when the wellhead temperature is greater than the wellhead target temperature T aim , stop heating, below the wellhead target temperature T aim , by starting heating.

[0077] By adding real-time monitoring and automatic start-stop modules to the electric heating circuit control system, when the wellhead temperature is greater than the wellhead target temperature T aim , the control system stops heating;

[0078] Lower than the wellhead target temperature T aim , the control system starts heating.

[0079] This cycle forms an operation control work system, which can always effectively replenish the heat loss dissipated by the well fluid to ensure that the medium temperature meets the requirements of the process flow.

[0080] Step 5.3: Abnormal wax plugging condition, continuous heating to unblock operation and regulation.

[0081] Depend on Figures 2 to 4 As shown, a shale oil well pressurized wax prevention and plugging removal system based on temperature compensation includes a ground power supply unit, a heating pipe cable running unit, and a well fluid temperature control unit. The ground power supply unit includes a main distribution box 102, the input end of the main distribution box 102 is connected to a step-down transformer, and the step-down transformer 101 is connected to a high-voltage transmission line 100; the output end of the main distribution box 102 is connected to a primary power cable 103, and the other end of the primary power cable 103 is connected to a secondary power cable 105 through a medium-frequency boost controller 104, and the secondary power cable 105 is connected to the heating pipe cable 301 through a wiring cavity 106.

[0082] The heating tube cable lowering unit comprises a main vehicle 501 and an auxiliary vehicle 505. The main vehicle 501 is provided with a main vehicle control room 502 and a heating tube cable drum 504. The main vehicle control room 502 is used to control the heating tube cable drum 504, thereby controlling the lowering of the heating tube cable 301. The heating tube cable drum 504 is connected with a cable arranger 503, so that the heating tube cable 301 can be evenly arranged on the heating tube cable drum 504. The injection head assembly 511 is provided on the upper part of the blowout preventer box 512. The clamping block is embedded on the outer side of the traction chain 510 inside the injection head assembly 511 to clamp the heating pipe cable 301 to overcome the buoyancy, top pressure and friction of the well fluid, and pass through the blowout preventer box 512 and the blowout preventer 513 to the specified depth underground; the upper part of the injection head assembly 511 is connected to the gooseneck 509, which is used to pull the heating pipe cable 301 to the injection head assembly 511 for introduction or export; the blowout preventer box 512 and the blowout preventer 513 have built-in sealing components, and the overall pressure resistance is 70MPa, so that the heating pipe cable 301 can be lowered under pressure to prevent the well fluid from overflowing. The auxiliary vehicle 505 is provided with an auxiliary vehicle control room 506 and a support frame 507, and the support frame 507 is provided with a hook 508. The hook 508 is adjusted by lifting and lateral movement to ensure that the injection head assembly 511, the blowout preventer box 512 and the blowout preventer 513 are aligned with the wellhead, which facilitates the bolt tightening of various connecting components.

[0083] The upper end of the heating cable 301 is connected to the heating cable lowering unit, and the lower end is connected to the submersible electric pump 401, and the lower end of the submersible electric pump 401 is connected to the downhole sensor 402. The well fluid temperature control unit includes an oil pressure and temperature monitoring device 202 and a casing pressure and temperature monitoring device 204. The temperature monitoring device 202 is installed at the end of the tubing gate valve 201, and the casing pressure and temperature monitoring device 204 is installed at the end of the casing gate valve 203; the oil pressure and temperature monitoring device 202 and the casing pressure and temperature monitoring device 204 are both connected to the main vehicle control room 502 in the heating cable lowering unit, and are used to receive temperature information, adjust the heating power in real time, and ensure that the outlet temperature is maintained at a constant target temperature.

[0084] The heating tube cable 301 includes a power transmission core wire 304, which is composed of multiple copper wires. An insulating layer 303 is provided outside the power transmission core wire 304, and a duplex stainless steel sheath 304 is provided outside the insulating layer 303. The duplex stainless steel sheath 302 fixes the power transmission core wire 304 and the insulating layer 303 into one, thereby realizing integrated power supply and heating.

[0085] Embodiment 1:

[0086] Step 1: Collect the depth H of the submersible pump in the shale oil well X1 and the temperature T at that depth down , original wellhead temperature T up and wax precipitation temperature T out The parameters are shown in Table 1.

[0087] Table 1 Basic parameters

[0088] Parameter Type Parameter Value Submersible pump lowering depth H 2149m <![CDATA[Temperature T at the lower pump down > 116℃ <![CDATA[Wellhead temperature T up > 32℃ <![CDATA[Wax appearance temperature T out > 46.42℃ <![CDATA[Desired target temperature T at the wellhead aim > 64℃ <![CDATA[Daily oil V oil > <![CDATA[8.7m 3 / d]]> <![CDATA[Nissan Water V water > <![CDATA[26.2m 3 / d]]> Oil production density ρoil <![CDATA[776.2kg / m 3 ]]> <![CDATA[Specific heat capacity C of oil oil > 2100J / (kg·℃)

[0089] Step 2: Based on the basic parameters provided in step 2, the wellhead temperature T up The wax precipitation temperature is 32℃, T out is 46.42℃, and the temperature at the wellhead is T up Less than the wax precipitation temperature T out , a heating pipe cable should be lowered to prevent wax from precipitating from the crude oil and blocking the oil pipe.

[0090] Step 3: Calculate the insertion depth L of the heating pipe and cable according to the basic parameters provided in the step;

[0091] Step 3.1: Estimate the temperature drop gradient from the pump depth to the wellhead in the wellbore: γ = (T down -T up ) / H.

[0092] Where: T down is the test temperature of the downhole sensor, which is 116°C here; T upis the temperature at the wellhead, which is 32°C here; H is the depth of the submersible pump, which is 2149m here. The estimated temperature drop gradient from the pump depth to the wellhead is γ = 3.91°C / 100m.

[0093] Step 3.2: Determine the initial insertion depth of the heating pipe cable: l = 100 (T aim -T up ) / γ;

[0094] Where: T aim is the expected target temperature at the wellhead, which is 64°C here.

[0095] Then l = (64-32) / 3.91 = 818.41m.

[0096] Step 3.3, calculate the depth L of the heating pipe and cable, taking into account the influence of the temperature drop gradient in the wellbore, the loss of heating depth due to the bending of the heating pipe and cable, and the influence of the wellhead temperature on the ambient temperature, and round the overall length. Here, the increased heating depth Δl is 31.59m.

[0097] The depth of the heating pipe cable is: L=l+Δl=818.41+31.59=850m.

[0098] Step 4: Calculate the power required by the heating system based on the parameters provided in step 4 and step 3:

[0099] Step 4.1. Calculate Q water =C water V water ρ water (T aim -T up ) / (3.6×10 6 )=4.2×10 3 ×26.2×10 3 ×(64-32) / (3.6×10 6 )=978.13kW.h,

[0100] Where: C water is the specific heat capacity of water, here it is 4.2×10 3 J / (kg·℃);

[0101] Step 4.2: Calculate Q oil =C oil V oil ρ oil (T aim -T up ) / (3.6×10 6 )=2.1×10 3 ×8.7×776.2×(64-32) / (3.6×10 6)=126.05kW.h;

[0102] Step 4.3: Calculate the power required by the heating system for well fluid temperature compensation: P 1 =(Q wate +Q oil ) / 24=(978.13+126.05) / 24=46kW.

[0103] Step 4.4, calculate the heating tube compensation power: P 2 =P 1 / L=46×10 3 / 850=54.12W / m.

[0104] Step 5: Control the start and stop of heating and the heating power according to the operating conditions of the oil well.

[0105] Step 5.1, in the initial stage of production, heating operation regulation. The initial heating power is set to 20% of the rated power, and the power is gradually increased by 20% of the rated power per hour to 80% of the rated power; if there is no sign of temperature rise or the wellhead target temperature is not reached at 80% of the rated power for 3 hours, the power is increased by 10% of the rated power until the wellhead target temperature T is reached. aim , here it is 64℃.

[0106] Step 5.2, intermittent heating control during stable operation. By adding real-time monitoring and automatic start-stop modules to the electric heating circuit control system, when the wellhead temperature is greater than the wellhead target temperature T aim , the control system stops heating; below the wellhead target temperature T aim , the control system starts heating. This cycle always effectively replenishes the heat loss dissipated by the well fluid, ensuring that the medium temperature meets the requirements of the process.

[0107] Step 5.3, abnormal wax plugging condition, continuous heating to unblock operation and control. Close the oil pipe production gate valve, increase the step-by-step power control system to the maximum, preliminarily design 12 hours of well heating, try to start the submersible pump 401, the downhole pressure sensor 402 monitors the downhole temperature pressure and the oil pressure and temperature monitoring device 202 at the wellhead to restore the operating parameters before the wax plugging state, and adjust to the intermittent heating system during stable operation. If the downhole pressure sensor 402 monitors the increase in motor temperature, the oil pressure and temperature monitoring device 202 maintain the wax plugging state parameters unchanged, the submersible pump 401 needs to be stopped, and the well heating continues for 12 hours; until the oil pressure and temperature monitoring device 202 restore the operating parameters before the wax plugging state, and then adjust to the intermittent heating system during stable operation.

[0108] By setting the operation mode under different working conditions, an automatic heating system with different changes in liquid production can be realized, which adapts to the production needs of shale oil wells with large fluctuations in liquid production. The system has a high safety factor and stable and reliable operation.

Claims

1. A method for preventing wax plugging in shale oil wells under pressure based on temperature compensation, characterized in that The following steps are involved: Step 1: Collect the depth H of the oil well submersible pump and the temperature T at that depth down , original wellhead temperature T up and wax precipitation temperature T out ; Step 2: Determine whether to lower the heating cable: If the wellhead temperature T up ≥T out , without inserting the heating pipe cable; if the wellhead temperature T up <T out , then put the heating pipe cable in; Step 3, calculating the insertion depth L of the heating pipe cable; Step 4, calculating the power P1 required by the heating system for well fluid temperature compensation; Step 5: Control the start and stop of heating and the heating power according to the operating conditions of the oil well.

2. The temperature compensation-based shale oil well pressure-based wax blocking and de-blocking method according to claim 1, characterized in that: The step 3 comprises: Step 3.1: Estimate the temperature drop gradient from the pump depth to the wellhead: γ=(T down -T up ) / H, Where: T down is the temperature at the depth where the submersible pump is located, °C; T up is the temperature at the wellhead, °C; H is the depth of the submersible pump, m; Step 3.2: Determine the initial depth of the heating tube cable: l=100(T aim -T up ) / γ, Where: Taim is the expected target temperature at the wellhead, °C. Step 3.3: Heating tube cable insertion depth: L=l+Δl, Where: Δl is the increased heating depth, which is the integer of the heating pipe cable insertion depth L.

3. The temperature compensation-based shale oil well pressure-based wax blocking and de-blocking method according to claim 2 is characterized in that: The step 4 comprises: Step 4.1: Calculate the heat Q released by the water component in the daily oil well production from the depth L to the wellhead water , kW·h, Q water =C water V water ρ water (T aim -T up ) / (3.6×10 6 ), Where: C water is the specific heat capacity of water, kg·℃; V water is the volume of water produced per day, m 3 / d;ρ water is the density of water, kg / m 3 ; Step 4.2: Calculate the heat Q released by the oil component in the daily production of the oil well from the depth L to the wellhead oil , kW·h, Q oil =C oil V oil ρ oil (T aim -T up ) / (3.6×10 6 ); Where: C water is the specific heat capacity of oil, kg·℃; V oil is the volume of oil produced per day, m 3 / d;ρ oil is the density of oil, kg / m 3 . Step 4.3: Calculate the power P1 required by the heating system for well fluid temperature compensation, kW: P1 = (Q wate +Q oil ) / twenty four.

4. The temperature compensation-based shale oil well pressure-based wax blocking and de-blocking method according to claim 3 is characterized in that: The step 4 also includes: Step 4.4: Calculate the heating pipe compensation power P2, W / m, based on the power P1 required by the heating system for well fluid temperature compensation and the heating pipe cable insertion depth L: P2=P1 / L.

5. The method for preventing wax plugging in shale oil wells under pressure based on temperature compensation according to claim 4 is characterized in that: The step 5 comprises: Step 5.1: Initial heating power is set to 20%-30% of the rated power, and gradually increased until the temperature at a certain power reaches the wellhead target temperature T aim , then run at this temperature; Step 5.2: During the stable operation of the oil well, when the wellhead temperature is greater than the wellhead target temperature T aim , stop heating, below the wellhead target temperature T aim , heated by startup; Step 5.3, wax blockage condition, continuous heating.

6. The temperature compensation-based shale oil well pressure-based wax prevention and plugging removal method according to claim 5 is characterized by: The step 5.1 comprises: Step 5.1.1: The initial heating power is set to 20%-30% of the rated power, and the power is gradually increased by 20% of the rated power per hour to 80% of the rated power. During the adjustment period, if the temperature reaches the target temperature T at a certain power aim Stop heating when Step 5.1.2: Run at 80% of rated power for 3 hours without reaching the target wellhead temperature T aim , and then increase the power by 10% of the rated power until the wellhead target temperature T is reached. aim .

7. A shale oil well pressure wax prevention and plugging removal system based on temperature compensation, comprising a ground power supply unit, a heating cable lowering unit, and a well fluid temperature control unit, characterized in that: The ground power supply unit is connected to the heating pipe cable (301), the upper end of the heating pipe cable (301) is connected to the heating pipe cable lowering unit, the lower end is connected to the submersible electric pump (401), and the lower end of the submersible electric pump (401) is connected to the downhole sensor (402); the well fluid temperature control unit comprises an oil pressure and temperature monitoring device (202) and a casing pressure and temperature monitoring device (204), and the temperature monitoring device (202) and the casing pressure and temperature monitoring device (204) are connected to the main vehicle control room (502) in the heating pipe cable lowering unit.

8. The temperature-compensated shale oil well pressure-based wax prevention and plugging removal system according to claim 7 is characterized in that: The ground power supply unit comprises a main distribution box (102), one end of the main distribution box (102) is connected to a high-voltage transmission line (100) via a step-down transformer (101), and the other end is connected to a primary power cable (103), the primary power cable (103) is connected to a secondary power cable (105) via a medium-frequency boost controller (104), and the secondary power cable (105) is connected to a heating pipe cable (301) via a wiring cavity (106).

9. The temperature-compensated shale oil well pressure-based wax prevention and plugging removal system according to claim 8 is characterized in that: The heating tube cable lowering unit comprises a main vehicle (501) and an auxiliary vehicle (505). The main vehicle (501) is provided with a main vehicle control room (502) and a heating tube cable drum (504). The auxiliary vehicle (505) is provided with an auxiliary vehicle control room (506) and a support frame (507). The heating tube cable (301) is controlled by the main vehicle control room (502) and lowered into the well along the heating tube cable drum (504). The support frame (507) is used to hoist a blowout preventer box (512) and a blowout preventer (513) to the wellhead via a hook (508).

10. The temperature-compensated shale oil well pressure-based wax prevention and plugging removal system according to claim 9, characterized in that: The heating tube cable (301) comprises a power transmission core wire (304), an insulating layer (303) is provided outside the power transmission core wire (304), and a duplex stainless steel sheath (304) is provided outside the insulating layer (303).

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