Liquid inlet balance control method for multiple parallel three-phase separators

Abstract

The invention discloses a liquid inlet balance control method for multiple parallel three-phase separators, which comprises the following steps: taking the water yield of the three-phase separators as a basic parameter of a flow regulating valve of a liquid inlet pipeline, when the water yield of a certain three-phase separator exceeds a certain range of an average value, calculating a ratio Px of a water yield difference value Xi to the current water yield Xi by a control system, and the opening degree of the flow regulating valve is regulated according to Px, so that rapid balance control over the liquid inlet amount of the multiple three-phase separators is achieved. According to the liquid inlet balance control method for the multiple parallel three-phase separators, the problem that the liquid inlet balance control effect of the three-phase separators is poor due to the fact that the gas content of crude oil is large and the liquid inlet amount is not measured accurately is solved, and the situation that crude oil treatment does not reach the standard due to the fact that the liquid inlet amount of a certain three-phase separator is too large due to bias flow is avoided.

Description

Technical Field

[0001] This invention belongs to the technical field of oilfield surface engineering construction methods, specifically relating to a method for controlling the liquid inlet balance of multiple parallel three-phase separators. Background Technology

[0002] Three-phase separators are key equipment in the oilfield surface engineering process, primarily used to separate oil, gas, and water from water-containing crude oil. Three-phase separator feed balance control involves adjusting the feed rate of each separator when multiple separators are operating in parallel, ensuring that the feed rate does not exceed the designed processing capacity of the separator, and preventing flow deviation that could lead to excessive feed rate to a particular separator and substandard crude oil processing.

[0003] In the existing process, water-containing crude oil enters three three-phase separators after passing through a separation buffer tank. Qualified crude oil (purified oil) with the required water content enters an external buffer tank, where it is pressurized and metered before being transported to the downstream station. Crude oil with insufficient water content is transported by auto-pressure to the station's settling tank for storage. The separated oilfield produced water enters the downstream produced water treatment system through the outlet pipeline of the three-phase separator's water chamber. The separated associated gas from the crude oil enters the downstream associated gas treatment system through the gas phase pipeline at the top of the three-phase separator.

[0004] To address the three-phase separator inlet flow control requirements of the above process, current automatic control is mainly based on the inlet flow rate signal, with two main control methods: 1. The control system sets the inlet flow rate SP for two three-phase separators, and controls the opening of the flow regulating valve according to the flow signal detected by the flow meter to keep the inlet flow rate at the set value; the flow regulating valve of the inlet pipeline of the third three-phase separator is fully open; 2. The control system sets the difference percentage SP of the inlet flow rates of the three three-phase separators (Note: the difference percentage is the difference between the inlet flow rate Fi of each line and the average inlet flow rate Fo). The percentage difference between △Fi and the average inlet flow rate Fo is calculated based on the inlet flow rate detected by the flow meter for each channel. The difference △Fi is then used to control the opening of the flow regulating valve on the corresponding pipeline (each regulating valve has an initial opening of 100%. When -SP*Fo≤△Fi≤SP*Fo, the opening remains unchanged. When △Fi>SP*Fo, the opening is reduced. When △Fi<-SP*Fo, the opening is increased). The percentage difference between the inlet flow rates of each channel is controlled within the set value range (-SP~+SP), thus achieving dynamic balance control of the inlet flow rate.

[0005] However, when the crude oil in the inlet pipeline of the three-phase separator has a large gas content, the crude oil in the inlet pipeline is a two-phase flow of gas and liquid, and the flow meter cannot accurately measure it. The current control method based on the inlet flow signal cannot achieve the expected control effect. Summary of the Invention

[0006] The purpose of this invention is to provide a liquid inlet balance control method for multiple parallel three-phase separators, which solves the problem of poor liquid inlet balance control effect of three-phase separators caused by high gas content in crude oil and inaccurate liquid inlet measurement.

[0007] The technical solution adopted in this invention is: a liquid inlet balance control method for multiple parallel three-phase separators. The water production of the three-phase separator is used as the basic parameter of the flow regulating valve of the liquid inlet pipeline. When the water production of a certain three-phase separator exceeds the average value by a certain range, the control system calculates the ratio Px of the water production difference ΔXi to the current water production Xi. The opening of the flow regulating valve is adjusted according to Px to achieve rapid balance control of the liquid inlet of multiple three-phase separators.

[0008] The technical solution adopted in this invention is also characterized by:

[0009] Furthermore, the liquid inlet balance control method for multiple parallel three-phase separators is implemented according to the following steps:

[0010] Step 1: For a process system with multiple parallel three-phase separators, set its initial conditions, including: I- Initial opening of the flow regulating valve of each three-phase separator inlet pipeline is 100%; II- Set the water production calculation time period Δt; III- Set the inlet balance control target value SP, i.e., the percentage difference of the target water production; IV- Set the regulating valve control cycle T.

[0011] Step 2: Calculate the water production Xi, average water production Xo, water production difference △Xi, percentage of water production difference Pi, and ratio Px of water production difference △Xi to water production Xi within the time period △t for each three-phase separator.

[0012] Step 3: Adjust the opening of the flow valve according to the calculation results in Step 2 to complete one adjustment control;

[0013] Step 4: Control of excessive liquid inlet. When all three-phase separators meet -SP≤Pi≤SP and at least one three-phase separator fails to process the crude oil to the required standard, adjust the opening of the liquid inlet flow regulating valve of the three-phase separator with the largest water production to 100%. The remaining three-phase separators continue to execute steps 2 to 4 until the opening of the liquid inlet regulating valve of all three-phase separators is adjusted to 100%.

[0014] Step 5: After the time interval t = T - Δt, repeat steps 1 to 4.

[0015] Furthermore, in step 1, the water production calculation time period △t and the control cycle T of the regulating valve are both determined based on the operating conditions: the water production calculation time period △t is set according to the metering accuracy of the flow meter and the normal operating flow rate, and the normal operating water production within △t is greater than or equal to 10 times the metering error value of the flow meter; the control cycle T of the regulating valve can be set according to the water production calculation time period △t and the control response time tx of the regulating valve opening, that is, T≥△t+tx.

[0016] Furthermore, step 2 is detailed below:

[0017] 1) Collect the water level Li(t1) of each three-phase separator water chamber, the cumulative flow Fi(t1) of the drain pipeline flow meter, the water level Li(t2) of the water chamber after Δt, and the cumulative flow Fi(t2) of the drain pipeline flow meter;

[0018] 2) Calculate the water production Xi of each three-phase separator during the time period Δt, as shown in formula (1):

[0019] Xi=G(Li(t2))-G(Li(t1))+Fi(t2)-Fi(t1) (1)

[0020] Where G is the function formula for calculating volume based on liquid level, i = 1, 2, ..., i is the number of parallel three-phase separators, t1 and t2 are parameter detection times, and t2 = t1 + Δt;

[0021] 3) Calculate the average water production rate Xo within the production Δt of each three-phase separator, as shown in formula (2):

[0022] Xo=∑△Xi / i (2)

[0023] 4) Calculate the difference in water production within Δt for each three-phase separator, ΔXi, and the percentage difference in water production, as shown in formulas (3) and (4):

[0024] △Xi=Xi-Xo (3)

[0025] Pi=△Xi / Xo (4)

[0026] 5) Calculate the ratio Px of the difference in water production within Δt between each three-phase separator and the water production within Δt, as shown in formula (5):

[0027] Px=△Xi / Xi (5).

[0028] Furthermore, in step 3, the opening of the flow regulating valve is adjusted according to the following conditions:

[0029] When Pi > SP, the opening of the corresponding flow regulating valve is reduced;

[0030] When Pi < -SP, the opening of the corresponding flow regulating valve is increased;

[0031] When -SP≤Pi≤SP, the opening degree of the corresponding flow regulating valve remains unchanged.

[0032] Furthermore, the adjustment range of the regulating valve opening is determined by Px. The larger Px is, the larger the adjustment range is, and vice versa.

[0033] Furthermore, in a process system with multiple parallel three-phase separators, when the water production of a certain three-phase separator exceeds the average value SP*Xo, this method is used to adjust the opening of the flow regulating valve to achieve rapid balance control of the influent flow.

[0034] The beneficial effects of this invention are:

[0035] This invention provides a method for controlling the liquid inlet balance of multiple parallel three-phase separators. The method uses the water production rate of the three-phase separators as the basic parameter for the flow regulating valve in the liquid inlet pipeline. When the water production rate of a certain three-phase separator exceeds the average value by a certain range (SP*Xo), the control system calculates the ratio Px of the water production rate difference ΔXi to the current water production rate Xi. Based on Px, the opening of the flow regulating valve is adjusted to achieve rapid balance control. This method can complete the liquid inlet balance control without collecting the liquid inlet data of gaseous crude oil, thus avoiding the problem of accurate metering of gaseous and liquid two-phase crude oil. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the process flow for the liquid inlet balance control method of multiple parallel three-phase separators of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer and more understandable, the technical solutions of this invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0038] This invention discloses a method for controlling the liquid inlet balance of multiple parallel three-phase separators, such as... Figure 1 As shown, the specific control method is as follows:

[0039] ① Initial conditions:

[0040] I - The initial opening of the flow regulating valve of each three-phase separator inlet line is 100%.

[0041] II - Set the time period for calculating water production △t (determined based on operating conditions).

[0042] III - Set the target value SP (percentage of difference in product water volume) for liquid inlet balance control.

[0043] IV - Set the control cycle T of the regulating valve (determined based on operating conditions)

[0044] ② Water volume calculation: Collect the water level Li(t1) of each three-phase separator water chamber, the cumulative flow Fi(t1) of the drain pipeline flow meter, the water level Li(t2) of the water chamber after a period of time Δt, and the cumulative flow Fi(t2) of the drain pipeline flow meter.

[0045] I - Calculate the water production of each three-phase separator during this time period (Δt).

[0046] Xi = G(Li(t2)) - G(Li(t1)) + Fi(t2) - Fi(t1), where G is the function formula for calculating volume based on liquid level; i = 2, ..., i, representing the number of parallel three-phase separators.

[0047] II - Calculate the average water production of each three-phase separator during this time period (Δt).

[0048] Xo=∑△Fi / i.

[0049] III - Calculate the difference in water production and the percentage difference for each three-phase separator during this time period (Δt).

[0050] △Xi=Xi-Xo.

[0051] Pi = △Xi / Xo.

[0052] IV - Calculate the ratio of the difference in water production rate of each three-phase separator during this time period (Δt) to the current water production rate Xi.

[0053] Px = △Xi / Xi.

[0054] ③ Flow regulating valve control:

[0055] When Pi > SP, the opening of the corresponding flow regulating valve is reduced;

[0056] When Pi < -SP, the opening of the corresponding flow regulating valve is increased;

[0057] When -SP≤Pi≤SP, the opening of the corresponding flow control valve remains unchanged;

[0058] The adjustment range of the valve opening is determined based on Px.

[0059] ④ This adjustment and control is now complete.

[0060] ⑤ After a time interval t = T - Δt, execute ② to ④ again to achieve automatic continuous control.

[0061] ⑥ Control of excessive total liquid inflow:

[0062] When all three-phase separators satisfy -SP≤Pi≤SP, and at least one three-phase separator fails to process the crude oil to the required standard, the control system automatically adjusts the opening of the inlet flow regulating valve of the substandard three-phase separator with the largest water production to 100%, while the remaining three-phase separators (number i = i-1) execute steps ② to ⑤. When i = 1, the opening of the inlet regulating valve of all three-phase separators is adjusted to 100%.

[0063] Example 1

[0064] The liquid inlet balance control method for multiple parallel three-phase separators uses the water production of the three-phase separator as the basic parameter of the flow regulating valve of the liquid inlet pipeline. When the water production of a certain three-phase separator exceeds the average value by a certain range, the control system calculates the ratio Px of the water production difference ΔXi to the current water production Xi, and adjusts the opening of the flow regulating valve according to Px to achieve rapid balance control of the liquid inlet of multiple three-phase separators.

[0065] The specific steps are as follows:

[0066] Step 1: For a process system with multiple parallel three-phase separators, set its initial conditions, including: I- Initial opening of the flow regulating valve of each three-phase separator inlet pipeline is 100%; II- Set the water production calculation time period Δt; III- Set the inlet balance control target value SP, i.e., the percentage difference of the target water production; IV- Set the regulating valve control cycle T.

[0067] Step 2: Calculate the water production Xi, average water production Xo, water production difference △Xi, percentage of water production difference Pi, and ratio Px of water production difference △Xi to water production Xi within the time period △t for each three-phase separator.

[0068] Step 3: Adjust the opening of the flow valve according to the calculation results in Step 2 to complete one adjustment control;

[0069] Step 4: Control of excessive liquid inlet. When all three-phase separators meet -SP≤Pi≤SP and at least one three-phase separator fails to process the crude oil to the required standard, adjust the opening of the liquid inlet flow regulating valve of the three-phase separator with the largest water production to 100%. The remaining three-phase separators continue to execute steps 2 to 4 until the opening of the liquid inlet regulating valve of all three-phase separators is adjusted to 100%.

[0070] Step 5: After the time interval t = T - Δt, repeat steps 1 to 4.

[0071] Example 2

[0072] The liquid inlet balance control method for multiple parallel three-phase separators uses the water production of the three-phase separator as the basic parameter of the flow regulating valve of the liquid inlet pipeline. When the water production of a certain three-phase separator exceeds the average value by a certain range, the control system calculates the ratio Px of the water production difference ΔXi to the current water production Xi, and adjusts the opening of the flow regulating valve according to Px to achieve rapid balance control of the liquid inlet of multiple three-phase separators.

[0073] The specific steps are as follows:

[0074] Step 1: For a process system with multiple parallel three-phase separators, set its initial conditions, including: I- Initial opening of the flow regulating valve of each three-phase separator inlet pipeline is 100%; II- Set the water production calculation time period Δt; III- Set the inlet balance control target value SP, i.e., the percentage difference of the target water production; IV- Set the regulating valve control cycle T.

[0075] The production water calculation time period △t and the control cycle T of the regulating valve are both determined according to the operating conditions: the production water calculation time period △t is set based on the metering accuracy of the flow meter and the normal operating flow rate. The normal operating water production within △t is greater than or equal to 10 times the metering error value of the flow meter; the control cycle T of the regulating valve can be set according to the production water calculation time period △t and the control response time tx of the regulating valve opening, that is, T≥△t+tx.

[0076] Step 2: Calculate the water production Xi, average water production Xo, water production difference △Xi, percentage of water production difference Pi, and ratio Px of water production difference △Xi to water production Xi within the time period △t for each three-phase separator.

[0077] Specifically as follows:

[0078] 1) Collect the water level Li(t1) of each three-phase separator water chamber, the cumulative flow Fi(t1) of the drain pipeline flow meter, the water level Li(t2) of the water chamber after Δt, and the cumulative flow Fi(t2) of the drain pipeline flow meter;

[0079] 2) Calculate the water production Xi of each three-phase separator during the time period Δt, as shown in formula (1):

[0080] Xi=G(Li(t2))-G(Li(t1))+Fi(t2)-Fi(t1) (1)

[0081] Where G is the function formula for calculating volume based on liquid level, i = 1, 2, ..., i is the number of parallel three-phase separators, t1 and t2 are parameter detection times, and t2 = t1 + Δt;

[0082] 3) Calculate the average water production rate Xo within the production Δt of each three-phase separator, as shown in formula (2):

[0083] Xo=∑△Xi / i (2)

[0084] 4) Calculate the difference in water production within Δt for each three-phase separator, ΔXi, and the percentage difference in water production, as shown in formulas (3) and (4):

[0085] △Xi=Xi-Xo (3)

[0086] Pi=△Xi / Xo (4)

[0087] 5) Calculate the ratio Px of the difference in water production within Δt between each three-phase separator and the water production within Δt, as shown in formula (5):

[0088] Px = △Xi / Xi (5);

[0089] Step 3: Adjust the opening of the flow valve according to the calculation results in Step 2 to complete one adjustment control;

[0090] Step 4: Control of excessive liquid inlet. When all three-phase separators meet -SP≤Pi≤SP and at least one three-phase separator fails to process the crude oil to the required standard, adjust the opening of the liquid inlet flow regulating valve of the three-phase separator with the largest water production to 100%. The remaining three-phase separators continue to execute steps 2 to 4 until the opening of the liquid inlet regulating valve of all three-phase separators is adjusted to 100%.

[0091] Step 5: After the time interval t = T - Δt, repeat steps 1 to 4.

[0092] Example 3

[0093] The liquid inlet balance control method for multiple parallel three-phase separators uses the water production of the three-phase separator as the basic parameter of the flow regulating valve of the liquid inlet pipeline. When the water production of a certain three-phase separator exceeds the average value by a certain range, the control system calculates the ratio Px of the water production difference ΔXi to the current water production Xi, and adjusts the opening of the flow regulating valve according to Px to achieve rapid balance control of the liquid inlet of multiple three-phase separators.

[0094] The specific steps are as follows:

[0095] Step 1: For a process system with multiple parallel three-phase separators, set its initial conditions, including: I- Initial opening of the flow regulating valve of each three-phase separator inlet pipeline is 100%; II- Set the water production calculation time period Δt; III- Set the inlet balance control target value SP, i.e., the percentage difference of the target water production; IV- Set the regulating valve control cycle T.

[0096] The production water calculation time period △t and the control cycle T of the regulating valve are both determined according to the operating conditions: the production water calculation time period △t is set based on the metering accuracy of the flow meter and the normal operating flow rate. The normal operating water production within △t is greater than or equal to 10 times the metering error value of the flow meter; the control cycle T of the regulating valve can be set according to the production water calculation time period △t and the control response time tx of the regulating valve opening, that is, T≥△t+tx.

[0097] Step 2: Calculate the water production Xi, average water production Xo, water production difference △Xi, percentage of water production difference Pi, and ratio Px of water production difference △Xi to water production Xi within the time period △t for each three-phase separator.

[0098] Specifically as follows:

[0099] 1) Collect the water level Li(t1) of each three-phase separator water chamber, the cumulative flow Fi(t1) of the drain pipeline flow meter, the water level Li(t2) of the water chamber after Δt, and the cumulative flow Fi(t2) of the drain pipeline flow meter;

[0100] 2) Calculate the water production Xi of each three-phase separator during the time period Δt, as shown in formula (1):

[0101] Xi=G(Li(t2))-G(Li(t1))+Fi(t2)-Fi(t1) (1)

[0102] Where G is the function formula for calculating volume based on liquid level, i = 1, 2, ..., i is the number of parallel three-phase separators, t1 and t2 are parameter detection times, and t2 = t1 + Δt;

[0103] 3) Calculate the average water production rate Xo within the production Δt of each three-phase separator, as shown in formula (2):

[0104] Xo=∑△Xi / i (2)

[0105] 4) Calculate the difference in water production within Δt for each three-phase separator, ΔXi, and the percentage difference in water production, as shown in formulas (3) and (4):

[0106] △Xi=Xi-Xo (3)

[0107] Pi=△Xi / Xo (4)

[0108] 5) Calculate the ratio Px of the difference in water production within Δt between each three-phase separator and the water production within Δt, as shown in formula (5):

[0109] Px = △Xi / Xi (5);

[0110] Step 3: Adjust the opening of the flow valve according to the calculation results in Step 2 to complete one adjustment control;

[0111] Adjust the flow control valve opening according to the following conditions:

[0112] When Pi > SP, the opening of the corresponding flow regulating valve is reduced;

[0113] When Pi < -SP, the opening of the corresponding flow regulating valve is increased;

[0114] When -SP≤Pi≤SP, the opening of the corresponding flow control valve remains unchanged;

[0115] The adjustment range of the regulating valve opening is determined by Px. The larger Px is, the larger the adjustment range is, and vice versa.

[0116] Step 4: Control of excessive liquid inlet. When all three-phase separators meet -SP≤Pi≤SP and at least one three-phase separator fails to process the crude oil to the required standard, adjust the opening of the liquid inlet flow regulating valve of the three-phase separator with the largest water production to 100%. The remaining three-phase separators continue to execute steps 2 to 4 until the opening of the liquid inlet regulating valve of all three-phase separators is adjusted to 100%.

[0117] Step 5: After the time interval t = T - Δt, repeat steps 1 to 4.

[0118] Example 4

[0119] The liquid inlet balance control method for multiple parallel three-phase separators uses the water production of the three-phase separator as the basic parameter of the flow regulating valve of the liquid inlet pipeline. When the water production of a certain three-phase separator exceeds the average value by a certain range, the control system calculates the ratio Px of the water production difference ΔXi to the current water production Xi, and adjusts the opening of the flow regulating valve according to Px to achieve rapid balance control of the liquid inlet of multiple three-phase separators.

[0120] The specific steps are as follows:

[0121] Step 1: For a process system with multiple parallel three-phase separators, set its initial conditions, including: I- Initial opening of the flow regulating valve of each three-phase separator inlet pipeline is 100%; II- Set the water production calculation time period Δt; III- Set the inlet balance control target value SP, i.e., the percentage difference of the target water production; IV- Set the regulating valve control cycle T.

[0122] The production water calculation time period △t and the control cycle T of the regulating valve are both determined according to the operating conditions: the production water calculation time period △t is set based on the metering accuracy of the flow meter and the normal operating flow rate. The normal operating water production within △t is greater than or equal to 10 times the metering error value of the flow meter; the control cycle T of the regulating valve can be set according to the production water calculation time period △t and the control response time tx of the regulating valve opening, that is, T≥△t+tx.

[0123] Step 2: Calculate the water production Xi, average water production Xo, water production difference △Xi, percentage of water production difference Pi, and ratio Px of water production difference △Xi to water production Xi within the time period △t for each three-phase separator.

[0124] Specifically as follows:

[0125] 1) Collect the water level Li(t1) of each three-phase separator water chamber, the cumulative flow Fi(t1) of the drain pipeline flow meter, the water level Li(t2) of the water chamber after Δt, and the cumulative flow Fi(t2) of the drain pipeline flow meter;

[0126] 2) Calculate the water production Xi of each three-phase separator during the time period Δt, as shown in formula (1):

[0127] Xi=G(Li(t2))-G(Li(t1))+Fi(t2)-Fi(t1) (1)

[0128] Where G is the function formula for calculating volume based on liquid level, i = 1, 2, ..., i is the number of parallel three-phase separators, t1 and t2 are parameter detection times, and t2 = t1 + Δt;

[0129] 3) Calculate the average water production rate Xo within the production Δt of each three-phase separator, as shown in formula (2):

[0130] Xo=∑△Xi / i (2)

[0131] 4) Calculate the difference in water production within Δt for each three-phase separator, ΔXi, and the percentage difference in water production, as shown in formulas (3) and (4):

[0132] △Xi=Xi-Xo (3)

[0133] Pi=△Xi / Xo (4)

[0134] 5) Calculate the ratio Px of the difference in water production within Δt between each three-phase separator and the water production within Δt, as shown in formula (5):

[0135] Px = △Xi / Xi (5);

[0136] Step 3: Adjust the opening of the flow valve according to the calculation results in Step 2 to complete one adjustment control;

[0137] Adjust the flow control valve opening according to the following conditions:

[0138] When Pi > SP, the opening of the corresponding flow regulating valve is reduced;

[0139] When Pi < -SP, the opening of the corresponding flow regulating valve is increased;

[0140] When -SP≤Pi≤SP, the opening of the corresponding flow control valve remains unchanged;

[0141] The adjustment range of the regulating valve opening is determined by Px. The larger Px is, the larger the adjustment range is, and vice versa.

[0142] Step 4: Control of excessive liquid inlet. When all three-phase separators meet -SP≤Pi≤SP and at least one three-phase separator fails to process the crude oil to the required standard, adjust the opening of the liquid inlet flow regulating valve of the three-phase separator with the largest water production to 100%. The remaining three-phase separators continue to execute steps 2 to 4 until the opening of the liquid inlet regulating valve of all three-phase separators is adjusted to 100%.

[0143] Step 5: After the time interval t = T - Δt, repeat steps 1 to 4.

[0144] In a process system with multiple parallel three-phase separators, when the water production of a certain three-phase separator exceeds the average value SP*Xo, this method is used to adjust the opening of the flow regulating valve to achieve rapid balance control of the influent flow.

Claims

1. A method for controlling the liquid inlet balance of multiple parallel three-phase separators, characterized in that, The water production rate of the three-phase separator is used as the basic parameter of the flow regulating valve of the inlet pipeline. When the water production rate of a certain three-phase separator exceeds the average value by a certain range, the control system calculates the ratio Px of the water production rate difference ΔXi to the current water production rate Xi. Based on Px, the opening of the flow regulating valve is adjusted to achieve rapid balance control of the inlet flow rate of multiple three-phase separators.

2. The liquid inlet balance control method for multiple parallel three-phase separators according to claim 1, characterized in that, The specific steps are as follows: Step 1: For a process system with multiple parallel three-phase separators, set its initial conditions, including: I- Initial opening of the flow regulating valve of each three-phase separator inlet pipeline is 100%; II- Set the water production calculation time period Δt; III- Set the inlet balance control target value SP, i.e., the percentage difference of the target water production; IV- Set the regulating valve control cycle T. Step 2: Calculate the water production Xi, average water production Xo, water production difference △Xi, percentage of water production difference Pi, and ratio Px of water production difference △Xi to water production Xi within the time period △t for each three-phase separator. Step 3: Adjust the opening of the flow valve according to the calculation results in Step 2 to complete one adjustment control; Step 4: Control of excessive liquid inlet. When all three-phase separators meet -SP≤Pi≤SP and at least one three-phase separator fails to process the crude oil to the required standard, adjust the opening of the liquid inlet flow regulating valve of the three-phase separator with the largest water production to 100%. The remaining three-phase separators continue to execute steps 2 to 4 until the opening of the liquid inlet regulating valve of all three-phase separators is adjusted to 100%. Step 5: After the time interval t = T - Δt, repeat steps 1 to 4.

3. The liquid inlet balance control method for multiple parallel three-phase separators according to claim 2, characterized in that, In step 1, the water production calculation time period Δt and the regulating valve control cycle T are both determined based on the operating conditions: the water production calculation time period Δt is set according to the metering accuracy of the flow meter and the normal operating flow rate, and the normal operating water production within Δt is greater than or equal to 10 times the flow meter metering error value; the regulating valve control cycle T can be set according to the water production calculation time period Δt and the regulating valve opening control response time tx, that is, T≥Δt+tx.

4. The liquid inlet balance control method for multiple parallel three-phase separators according to claim 2, characterized in that, Step 2 is described in detail below: 1) Collect the water level Li(t1) of each three-phase separator water chamber, the cumulative flow Fi(t1) of the drain pipeline flow meter, the water level Li(t2) of the water chamber after Δt, and the cumulative flow Fi(t2) of the drain pipeline flow meter; 2) Calculate the water production Xi of each three-phase separator during the time period Δt, as shown in formula (1): Xi=G(Li(t2))-G(Li(t1))+Fi(t2)-Fi(t1) (1) Where G is the function formula for calculating volume based on liquid level, i = 1, 2, ..., i is the number of parallel three-phase separators, t1 and t2 are parameter detection times, and t2 = t1 + Δt; 3) Calculate the average water production rate Xo within the production Δt of each three-phase separator, as shown in formula (2): Xo=∑△Xi / i (2) 4) Calculate the difference in water production within Δt for each three-phase separator, ΔXi, and the percentage difference in water production, as shown in formulas (3) and (4): △Xi=Xi-Xo (3) Pi=△Xi / Xo (4) 5) Calculate the ratio Px of the difference in water production within Δt between each three-phase separator and the water production within Δt, as shown in formula (5): Px=△Xi / Xi (5).

5. The liquid inlet balance control method for multiple parallel three-phase separators according to claim 3, characterized in that, In step 3, the opening of the flow regulating valve is adjusted according to the following conditions: When Pi > SP, the opening of the corresponding flow regulating valve is reduced; When Pi < -SP, the opening of the corresponding flow regulating valve is increased; When -SP≤Pi≤SP, the opening degree of the corresponding flow regulating valve remains unchanged.

6. The liquid inlet balance control method for multiple parallel three-phase separators according to claim 4, characterized in that, The adjustment range of the valve opening is determined by Px. The larger Px is, the larger the adjustment range is, and vice versa.

7. The liquid inlet balance control method for multiple parallel three-phase separators according to any one of claims 1 to 6, characterized in that, In a process system with multiple parallel three-phase separators, when the water production of a certain three-phase separator exceeds the average value SP*Xo, this method is used to adjust the opening of the flow regulating valve to achieve rapid balance control of the influent flow.

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