Concentric and independent three-channel accurate injection method for oil field polymer

Abstract

A concentric and independent three-channel precise injection method for oil field polymers comprises the steps that (a) a concentric three-channel tubular column is formed by sequentially sleeving a central tube, a middle-layer tube and an outer tube from inside to outside to form three independent fluid channels; the quality-divided supercharger is arranged at a wellhead and comprises three independent channels, each channel is internally provided with a fan blade with adjustable rotating speed, and the fan blades are used for adjusting the molecular weight and the injection pressure of the polymer solution according to the permeability of a target stratum; the control system is connected with the pressure sensor, the flow meter and the quality-divided supercharger and used for adjusting the rotating speed of the fan blades and injection parameters of all the channels in real time according to preset parameters, the structure is novel, the testing process is simplified, the allocation efficiency is improved, the testing process is effectively simplified, the situation that testing is complex in the traditional technology is changed, and the testing efficiency is improved. And meanwhile, the layered water volume allocation efficiency is improved, and time and labor cost are saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield development, in particular to a method for precise injection of oilfield polymer through three independent concentric channels. BACKGROUND

[0002] In the middle and later stages of oilfield development, with the continuous deepening of the exploitation degree, the problem of reservoir heterogeneity is increasingly prominent, which is characterized by large interlayer permeability ratio and significant vertical contradictions. These problems directly lead to the difficulty of traditional polymer flooding technology in achieving precise and efficient injection of different permeability layers, which seriously restricts the further improvement of oilfield recovery.

[0003] Currently, the commonly used polymer flooding injection technology in the industry mainly includes ring-type pressure reduction groove concentric injection process and single pipe quality and pressure injection process, but these technologies have obvious limitations:

[0004] Complex testing process: During the injection process, the monitoring and testing process of injection parameters for each layer is complicated, and frequent pipe column lifting or complex downhole instruments are required, which not only increases the operation time and cost, but also may cause additional disturbance to the oil layer. SUMMARY

[0005] In view of the above situation, in order to overcome the defects of the prior art, the present application provides a method for precise injection of oilfield polymer through three independent concentric channels, which effectively solves the problems mentioned in the background art.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme: the present application comprises:

[0007] (a) concentric three-channel pipe column: the center pipe, the middle layer pipe and the outer pipe are sequentially sleeved from inside to outside, forming three independent fluid channels:

[0008] Pipe column first channel: the inner cavity of the center pipe;

[0009] Pipe column second channel: the annular space between the center pipe and the middle layer pipe;

[0010] Pipe column third channel: the annular space between the middle layer pipe and the outer pipe;

[0011] (b) quality booster: provided at the wellhead, including three independent channels, each channel is provided with a fan blade with adjustable speed, used to adjust the molecular weight and injection pressure of the polymer solution according to the permeability of the target formation:

[0012] The first channel of the quality booster outputs polymer solution with high molecular weight and low injection pressure to the third channel of the pipe column;

[0013] The second channel of the quality booster outputs polymer solution with medium molecular weight and medium injection pressure to the second channel of the pipe column;

[0014] The third channel of the fractional booster outputs a low molecular weight, high injection pressure polymer solution to the first channel of the tubing;

[0015] (c) Monitoring and control system: including:

[0016] Pressure sensors and flow meters are installed at the wellheads of each fluid channel;

[0017] The control system is connected to the pressure sensor, flow meter and fractional booster, and is used to adjust the fan blade speed and injection parameters of each channel in real time according to preset parameters.

[0018] According to the above technical solution: the fan blade speed of the fractional booster is driven by a servo motor, and the power supply system of the servo motor includes a solar panel and an energy storage battery.

[0019] According to the above technical solution: the end of the concentric three-channel tubing is connected to a filler and a packer to isolate each target formation.

[0020] According to the above technical solution: the central tube, the middle tube and the outer tube are made of corrosion-resistant alloy material, and the inner wall is smoothed.

[0021] A method for precise injection of polymer concentric independent three-channel systems in oilfields includes the following steps:

[0022] (a) Parameter preset: Based on the permeability differences of the target formation, set the target values ​​for the injection parameters of each channel, including:

[0023] Target parameters for the third channel of the tubing string in high-permeability formations: high molecular weight and low injection pressure;

[0024] Target parameters for the second channel of the tubing string corresponding to medium-permeability formations: medium molecular weight and medium injection pressure;

[0025] Target parameters for the first channel of the tubing string in low-permeability formations: low molecular weight, high injection pressure;

[0026] (b) Solution fractionation: The polymer mother liquor is fed into the fractionation booster, and the speed of the fan blades in the three channels is adjusted independently:

[0027] The fan blades of the first channel of the fractional booster remain at low speed or stop, outputting a high molecular weight, low injection pressure solution to the annular space between the middle layer tube and the outer tube.

[0028] The fan blades of the second channel of the fractional booster operate at medium speed, outputting a medium molecular weight, medium injection pressure solution into the annular space between the central tube and the middle layer tube.

[0029] The fan of the third passage of the multi-quality booster runs at high speed, and outputs a low molecular weight and high injection pressure solution to the inner cavity of the central pipe;

[0030] (c) Layered injection and real-time regulation:

[0031] The flow rate data and pressure data of each passage are collected in real time by monitoring the regulation system;

[0032] The control system compares the collected data with the target parameters preset in step (a):

[0033] If the flow rate deviates from the target value, adjust the valve opening of the corresponding passage;

[0034] If the molecular weight deviates from the target value, adjust the fan speed of the multi-quality booster corresponding to the passage;

[0035] If the injection pressure deviates from the target value, adjust the valve opening and fan speed simultaneously;

[0036] (d) Dynamic matching of the formation: through the closed-loop regulation of step (c), the molecular weight and injection pressure of the polymer solution output by each passage continuously match the permeability characteristics of the corresponding formation.

[0037] According to the above technical solution: in step (c), when the pressure of a certain passage exceeds the preset upper limit, the valve opening of the passage is automatically increased and the corresponding fan speed is reduced; when the pressure is lower than the preset lower limit, the valve opening is reduced and the fan speed is increased.

[0038] According to the above technical solution: in step (b), the fan speed adjustment range of the multi-quality booster is 1000-3000 rpm, and satisfies:

[0039] The fan speed of the first passage of the multi-quality booster is ≤1500 rpm, so that the molecular weight of the polymer is reduced by ≤10%;

[0040] The fan speed of the second passage of the multi-quality booster is 1500-2500 rpm, so that the molecular weight of the polymer is reduced by 10%-30%;

[0041] The fan speed of the third passage of the multi-quality booster is ≥2500 rpm, so that the molecular weight of the polymer is reduced by ≥30%.

[0042] According to the above technical solution: in step (c), the basis for determining whether the molecular weight deviates from the target value is:

[0043] The viscosity of the solution at the outlet of the multi-quality booster is monitored in real time;

[0044] The actual molecular weight is converted through the preset viscosity-molecular weight corresponding relationship curve;

[0045] If the actual molecular weight deviates from the target molecular weight by more than ±5%, adjust the corresponding fan speed.

[0046] According to the above technical solution: in step (c), when the flow of a certain channel continuously falls below the target value and the pressure rises, a staged response is performed:

[0047] Preferably, increase the opening of the channel valve to the maximum allowed value;

[0048] If the flow still does not meet the standard, increase the corresponding fan speed to reduce the molecular weight;

[0049] If the pressure exceeds the safety threshold, trigger an emergency injection stop.

[0050] According to the above technical solution: in step (d), update the target parameters according to the dynamic changes in formation permeability, including:

[0051] Obtain the liquid production profile data of each interval every 30 days;

[0052] If the liquid absorption ratio of a certain interval changes by more than ±15%, reset the molecular weight and pressure target value of the corresponding channel for that interval.

[0053] Beneficial effects: precise injection of three-layer segments with different qualities and pressures: the three-layer segments can be simultaneously injected with different qualities and pressures, and the injection amount of each interval can be accurately controlled at the wellhead, solving the problem of simultaneous injection of three or more intervals with different qualities and pressures in the prior art.

[0054] Simplify the testing process and improve the deployment efficiency: effectively simplify the testing process, change the complex situation of traditional technology testing, and at the same time improve the deployment efficiency of stratified water volume, save time and labor cost.

[0055] Improve oil displacement effect and recovery rate: through precise control and adjustment of the pressure and polymer molecular weight of each interval, the polymer solution can better match the permeability of different oil layers. For high permeability layers, high molecular weight, low injection pressure polymer solution is used to avoid injection breakthrough; for low permeability layers, polymer solutions with suitable molecular weight and pressure for their permeability are used respectively, thereby improving injection capacity, enhancing oil displacement effect, increasing oil well production, and improving recovery rate.

[0056] Ensure stable and reliable injection process: real-time monitoring and control system can obtain information such as injection pressure, flow rate and polymer solution parameters of each interval in time, find problems in the injection process in time, and make rapid adjustments to ensure the stability and reliability of the injection process.

[0057] Reduce cost and maintenance workload: due to the stable and reliable injection process, additional cost expenditure caused by injection problems is reduced, and the maintenance workload of equipment is reduced, improving the economic efficiency of oilfield development. Attached Figure Description

[0058] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0059] Figure 1 This is a schematic diagram of the concentric three-channel fractional pressure injection column structure of the present invention;

[0060] Figure 2 This is a schematic diagram of the three-channel wellhead structure of the injection system of the present invention;

[0061] Figure 3 This is a schematic diagram of the fractional-pressure boosting structure of the present invention;

[0062] Figure 4 This is a flowchart of the method of the present invention. Detailed Implementation

[0063] The following is in conjunction with the appendix Figures 1-4 The specific embodiments of the present invention will be described in further detail below.

[0064] Example 1, by Figures 1-4 The present invention provides an oilfield polymer concentric independent three-channel precision injection device, comprising:

[0065] a. Concentric three-channel tubing: The central tube 4, the middle tube 5, and the outer tube 6 are sequentially nested from the inside out, forming three independent fluid channels:

[0066] First channel of the tubing: the inner cavity of the central tube 4;

[0067] Second channel of the tubing: the annular space between the central tube 4 and the middle tube 5;

[0068] The third channel of the tubing: the annular space between the middle tube 5 and the outer tube 6;

[0069] b. Fractional booster: Located at the wellhead, it includes three independent channels, each equipped with adjustable-speed fan blades 314, used to adjust the molecular weight of the polymer solution and the injection pressure according to the permeability of the target formation.

[0070] The first channel of the fractional booster outputs a high molecular weight, low injection pressure polymer solution to the third channel of the tubing;

[0071] The second channel of the fractional booster outputs a polymer solution with medium molecular weight and medium injection pressure to the second channel of the column;

[0072] The third channel of the fractional booster outputs a low molecular weight, high injection pressure polymer solution to the first channel of the tubing;

[0073] A monitoring and control system is provided, comprising:

[0074] Pressure sensors 2, 210, 214, 218 and flow meters 211, 215, 219 are arranged at the wellheads of the fluid channels;

[0075] A control system is connected to the pressure sensors 2, 210, 214, 218, flow meters 211, 215, 219 and the separate- quality booster, for adjusting the rotation speed of the fan blades and the injection parameters of each channel in real time according to preset parameters.

[0076] The rotation speed of the fan blades 314 of the separate- quality booster is driven by a servo motor 34, and the power supply system of the servo motor 34 comprises a solar panel 31 and an energy storage battery 32.

[0077] The distal end of the concentric three-channel pipe string is connected to an injection distributor 11 and packers 8, 9, 10 for isolating each target formation.

[0078] The center pipe 4, the middle pipe 5 and the outer pipe 6 are made of corrosion-resistant alloy materials, and the inner walls are smooth.

[0079] A method for precise injection of oilfield polymers in a concentric independent three-channel, comprising the following steps:

[0080] (a) Parameter presetting: according to the permeability difference of the target formation, set the target value of the injection parameters of each channel, including:

[0081] The target parameters of the third channel of the pipe string corresponding to the high permeability formation: high molecular weight, low injection pressure;

[0082] The target parameters of the second channel of the pipe string corresponding to the medium permeability formation: medium molecular weight, medium injection pressure;

[0083] The target parameters of the first channel of the pipe string corresponding to the low permeability formation: low molecular weight, high injection pressure;

[0084] (b) Solution separate- quality treatment: input the polymer mother liquor into the separate- quality booster, and independently adjust the rotation speed of the fan blades 314 in the three channels:

[0085] The fan blades of the first channel of the separate- quality booster remain at low speed or stop, and output high molecular weight, low injection pressure solution to the annular space between the middle pipe 5 and the outer pipe 6;

[0086] The fan blades of the second channel of the separate- quality booster rotate at medium speed, and output medium molecular weight, medium injection pressure solution to the annular space between the center pipe 4 and the middle pipe 5;

[0087] The fan blades of the third channel of the separate- quality booster rotate at high speed, and output low molecular weight, high injection pressure solution to the inner cavity of the center pipe 4;

[0088] (c) Layered injection with real-time regulation:

[0089] Real-time acquisition of flow rate and pressure data of each channel by monitoring the regulation system;

[0090] Comparison of the acquired data by the control system with the target parameters preset in step (a):

[0091] If the flow rate deviates from the target value, adjust the valve opening of the corresponding channel;

[0092] If the molecular weight deviates from the target value, adjust the corresponding fan speed of the molecular weight booster;

[0093] If the injection pressure deviates from the target value, adjust the valve opening and fan speed simultaneously;

[0094] (d) Dynamic matching of the formation: through the closed-loop regulation of step (c), the molecular weight and injection pressure of the polymer solution output by each channel continuously match the permeability characteristics of the corresponding formation.

[0095] In step (c), when the pressure of a certain channel exceeds the preset upper limit, automatically increase the valve opening of the channel and reduce the corresponding fan speed; when the pressure is lower than the preset lower limit, reduce the valve opening and increase the fan speed.

[0096] In step (b), the fan speed adjustment range of the molecular weight booster is 1000-3000 rpm, and satisfies:

[0097] The fan speed of the first channel of the molecular weight booster is ≤1500 rpm, so that the decrease in polymer molecular weight is ≤10%;

[0098] The fan speed of the second channel of the molecular weight booster is 1500-2500 rpm, so that the decrease in polymer molecular weight is 10%-30%;

[0099] The fan speed of the third channel of the molecular weight booster is ≥2500 rpm, so that the decrease in polymer molecular weight is ≥30%.

[0100] In step (c), the basis for determining the deviation of the molecular weight from the target value is:

[0101] Real-time monitoring of the viscosity of the solution at the outlet of the molecular weight booster;

[0102] Through the preset viscosity-molecular weight correspondence curve, the actual molecular weight is converted;

[0103] If the actual molecular weight deviates from the target molecular weight by more than ±5%, adjust the corresponding fan speed.

[0104] In step (c), when the flow rate of a certain channel continuously deviates from the target value and the pressure rises, perform a hierarchical response:

[0105] The channel valve opening is increased to the maximum allowable value;

[0106] If the flow rate still does not meet the standard, the corresponding fan speed is increased to reduce the molecular weight;

[0107] If the pressure exceeds the safety threshold, trigger the emergency stop.

[0108] In step (d), the target parameters are updated according to the dynamic changes in formation permeability, including:

[0109] Every 30 days, obtain the liquid production profile data of each interval;

[0110] If the liquid absorption ratio of a certain interval changes by more than ±15%, reset the molecular weight and pressure target values of the corresponding channel for that interval.

[0111] Parameter presetting (a): According to the permeability difference of the target formation, set the injection parameter target values of each channel:

[0112] The third channel target parameters of the pipe string corresponding to the high permeability formation: high molecular weight, low injection pressure.

[0113] The second channel target parameters of the pipe string corresponding to the medium permeability formation: medium molecular weight, medium injection pressure.

[0114] The first channel target parameters of the pipe string corresponding to the low permeability formation: low molecular weight, high injection pressure.

[0115] Solution fractionation treatment (b): The polymer mother liquor is input into the fractionation booster, and by independently adjusting the rotation speed of the fan 314 in the three channels, different characteristics of the polymer solution are obtained:

[0116] Fan speed range: The fan speed adjustment range of the fractionation booster is 1000-3000 rpm.

[0117] Channel adjustment and output

[0118] The first channel fan of the fractionation booster remains low speed or stops rotating, with a rotation speed ≤1500 rpm, so that the polymer molecular weight decreases by ≤10%, and a high molecular weight, low injection pressure solution is output to the annular space between the middle layer pipe 5 and the outer pipe 6.

[0119] The second channel fan of the fractionation booster operates at medium speed, with a rotation speed of 1500-2500 rpm, so that the polymer molecular weight decreases by 10%-30%, and a medium molecular weight, medium injection pressure solution is output to the annular space between the center pipe 4 and the middle layer pipe 5.

[0120] The third channel fan of the fractionation booster operates at high speed, with a rotation speed ≥2500 rpm, so that the polymer molecular weight decreases by ≥30%, and a low molecular weight, high injection pressure solution is output to the lumen of the center pipe 4.

[0121] Layered injection and real-time regulation (c) Data collection: Collect the flow rate and pressure data of each channel in real time by monitoring the regulation system.

[0122] Data comparison and adjustment: The control system compares the collected data with the target parameters set in step (a) and makes corresponding adjustments:

[0123] If the flow rate deviates from the target value, adjust the valve opening of the corresponding channel.

[0124] If the molecular weight deviates from the target value, adjust the fan speed of the molecular weight booster. The judgment basis for the deviation of the molecular weight from the target value is: real-time monitoring of the viscosity of the solution at the outlet of the molecular weight booster, and through the preset viscosity-molecular weight corresponding relationship curve, the actual molecular weight is calculated, if the actual molecular weight deviates from the target molecular weight by more than ±5%, the corresponding fan speed is adjusted.

[0125] If the injection pressure deviates from the target value, adjust the valve opening and fan speed simultaneously. When the pressure of a certain channel exceeds the preset upper limit, automatically increase the valve opening of the channel and reduce the corresponding fan speed; when the pressure is lower than the preset lower limit, reduce the valve opening and increase the fan speed.

[0126] Special case handling: When the flow rate of a certain channel continuously falls below the target value and the pressure rises, perform a hierarchical response: preferentially increase the valve opening of the channel to the maximum allowed value; if the flow rate still does not meet the standard, increase the corresponding fan speed to reduce the molecular weight; if the pressure exceeds the safety threshold, trigger an emergency injection stop.

[0127] Dynamic matching of the formation (d): Through the closed-loop regulation of step (c), the molecular weight and injection pressure of the polymer solution output by each channel continuously match the permeability characteristics of the corresponding formation. At the same time, update the target parameters according to the dynamic changes of the formation permeability, specifically: obtain the liquid production profile data of each interval every 30 days, if the liquid absorption ratio of a certain interval changes by more than ±15%, reset the molecular weight and pressure target value of the corresponding channel of the layer.

[0128] Example: I. Preparation stage

[0129] 1. Geological data collection and analysis

[0130] Collect detailed geological data of the target reservoir, including permeability, thickness, porosity, crude oil viscosity and other parameters of each interval, and determine the distribution range and boundary of high, medium and low permeability layers.

[0131] Through early-stage well testing, logging and other means, obtain the liquid absorption capacity and pressure response characteristics of each interval to provide basis for subsequent injection parameter setting.

[0132] 2. Equipment selection and debugging

[0133] According to the depth of the oil reservoir, the size of the wellbore and the injection pressure requirements, select the appropriate concentric three-channel pipe column assembly, including three-channel tubing, three-channel concentric pack-off and injection integrated packer, two-channel concentric tubing, two-channel concentric pack-off and injection integrated packer, packer, injector, etc. Ensure that the sizes of the components match and the materials are corrosion-resistant alloys. The inner wall is smooth to reduce fluid resistance.

[0134] Debug the quality booster, check the flexibility of the three-channel fan blades, test the operation stability of the servo motor and reducer, and ensure that the fan blade speed can be accurately adjusted within the range of 1000-3000 rpm (low speed ≤1500 rpm, medium speed 1500-2500 rpm, high speed ≥2500 rpm).

[0135] Install and calibrate the monitoring and control system, including pressure sensors, flow sensors, and ground control systems, to ensure that the sensor measurement error is ≤±2% and the data transmission delay is ≤1 second.

[0136] Check the solar power supply system, including the photoelectric conversion efficiency of the solar panels, the storage capacity of the storage batteries, and the switching reliability of the power conversion relay, to ensure that the equipment can operate stably for ≥72 hours under continuous rainy weather.

[0137] II. Pipe column lowering and installation

[0138] 1. Downhole pipe column assembly and lowering

[0139] Connect the downhole components in the following order and lower them into the well:

[0140] First, connect the dead plug and the injector, then connect the packer, and slowly lower it to the designed depth, ensuring that the packer setting position avoids the casing coupling (error ≤0.5 meters).

[0141] Connect the two-channel concentric pack-off and injection integrated packer and the two-channel concentric tubing, continue to lower into the well, and confirm the pipe column depth deviation ≤±0.1 meters through the wellhead depth calibration tool.

[0142] Finally, connect the three-channel concentric pack-off and injection integrated packer and the three-channel concentric tubing, and after lowering into the well, use the pipe column gravity and setting tool to complete the setting of the packer, ensuring that the isolation pressure of each layer is ≥10 MPa.

[0143] 2. Wellhead device connection

[0144] Install a three-channel integrated wellhead at the wellhead, and connect the first, second, and third injection channels of the wellhead to the corresponding channels of the three-channel tubing:

[0145] First injection channel → center pipe channel

[0146] Secondary injection channel → annular channel between middle pipe and central pipe

[0147] Tertiary injection channel → annular channel between outer pipe and middle pipe

[0148] Connecting the fractional booster to the wellhead channel, ensuring:

[0149] Fractional booster first channel (high molecular weight, low pressure) → wellhead tertiary injection channel (corresponding to high permeability layer)

[0150] Fractional booster second channel (medium molecular weight, medium pressure) → wellhead secondary injection channel (corresponding to medium permeability layer)

[0151] Fractional booster third channel (low molecular weight, high pressure) → wellhead primary injection channel (corresponding to low permeability layer)

[0152] Connecting the polymer mother liquor conveying pipeline to the fractional booster inlet, installing a sampling gate for subsequent solution parameter detection.

[0153] Three, injection parameter setting

[0154] 1. Fractional pressure parameter determination

[0155] According to the permeability characteristics of each layer, set the polymer solution parameters:

[0156] High permeability layer: use high molecular weight polymer solution (molecular weight drop ≤10%), injection pressure ≤80% of the formation fracture pressure, flow rate set to 10-20 m 3 / d.

[0157] Medium permeability layer: use medium molecular weight polymer solution (molecular weight drop 10%-30%), injection pressure 80%-90% of the formation fracture pressure, flow rate 5-15 m 3 / d.

[0158] Low permeability layer: use low molecular weight polymer solution (molecular weight drop ≥30%), injection pressure ≤95% of the formation fracture pressure, flow rate 3-10 m 3 / d.

[0159] Through the ground control system, preset the upper limit (automatic adjustment when exceeded) and lower limit (alarm when below) of the pressure of each channel, with a deviation range of ±5%.

[0160] 2. Selecting the injection core

[0161] According to the set flow rate parameters, select the corresponding specification of the injection core to be installed in each injection channel, ensuring that the flow rate regulation accuracy of the injection core is ≥90%.

[0162] Four, injection process control

[0163] 1. Fractionation and injection start

[0164] Polymer mother liquor is pumped into the fractionation booster, and the servo motor drives the fan blade to rotate:

[0165] High permeability layer channel: low speed operation of the fan blade (≤1500 rpm), output of high molecular weight, low pressure solution, through the three-stage injection channel, the outer tube and the middle layer tube annular channel injection into the high permeability layer.

[0166] Medium permeability layer channel: medium speed operation of the fan blade (1500-2500 rpm), output of medium molecular weight, medium pressure solution, through the two-stage injection channel, the middle layer tube and the center tube annular channel injection into the medium permeability layer.

[0167] Low permeability layer channel: high speed operation of the fan blade (≥2500 rpm), output of low molecular weight, high pressure solution, through the one-stage injection channel, the center tube injection into the low permeability layer.

[0168] When starting the injection system, a step-by-step pressure boosting method is used, the initial pressure is 50% of the target pressure, and it is increased by 10% every 30 minutes until the preset pressure is reached, to avoid the impact of sudden pressure changes on the formation.

[0169] 2. Real-time monitoring and control

[0170] The monitoring system collects the following data in real time and transmits them to the ground control system:

[0171] Injection pressure of each channel (accuracy ±0.1 MPa), flow rate (accuracy ±0.1 m 3 / d)

[0172] Viscosity of the outlet solution of the fractionation booster (used to convert molecular weight, error ≤±3%)

[0173] The control system adjusts in a closed loop according to the monitoring data:

[0174] Flow deviation: when the actual flow rate deviates from the target value by >±5%, automatically adjust the valve opening of the corresponding channel (adjustment accuracy ±1%).

[0175] Molecular weight deviation: convert the actual molecular weight through the viscosity-molecular weight curve, if the deviation from the target value is >±5%, adjust the fan blade speed of the corresponding channel (adjustment step 50 rpm).

[0176] Pressure deviation: when the pressure is higher than the upper limit, increase the valve opening (step 2%) and reduce the fan blade speed (step 100 rpm); when the pressure is lower than the lower limit, reduce the valve opening (step 2%) and increase the fan blade speed (step 100 rpm).

[0177] 3. Special case handling

[0178] When the flow of a certain channel is less than 10% of the target value for 30 minutes and the pressure rises:

[0179] Preferably, the valve opening of the channel is increased to the maximum allowed value (≤90%).

[0180] If the flow still does not meet the standard, increase the corresponding fan speed (each increase by 200 rpm, upper limit 3000 rpm).

[0181] If the pressure exceeds the safety threshold (100% of the formation fracture pressure), trigger an emergency injection, close the channel valve and issue an alarm.

[0182] Beneficial effects: Achieve precise injection of three layers with different qualities and pressures: The system can simultaneously perform precise injection of three layers with different qualities and pressures, and the injection volume of each layer can be accurately controlled at the wellhead, solving the problem of simultaneous injection of three or more layers with different qualities and pressures in the prior art.

[0183] Simplify the testing process and improve the deployment efficiency: The testing process is effectively simplified, changing the complex situation of traditional technology testing, while improving the deployment efficiency of layered water volume, saving time and labor cost.

[0184] Improve oil displacement effect and recovery rate: By precisely controlling and adjusting the pressure and polymer molecular weight of each layer, the polymer solution can better match the permeability of different oil layers. For high permeability layers, high molecular weight, low injection pressure polymer solution is used to avoid injection breakthrough; for low permeability layers, polymer solutions with suitable molecular weight and pressure for their permeability are used respectively, thereby improving injection capacity, enhancing oil displacement effect, increasing oil well production, and improving recovery rate.

[0185] Ensure stable and reliable injection process: Real-time monitoring and control system can timely obtain information such as injection pressure, flow rate and polymer solution parameters of each layer, timely discover problems in the injection process, and make rapid adjustments to ensure the stability and reliability of the injection process.

[0186] Reduce cost and maintenance workload: Due to the stable and reliable injection process, additional cost expenditure caused by injection problems is reduced, and the maintenance workload of equipment is also reduced, improving the economic efficiency of oilfield development.

[0187] According to the permeability difference of the target formation, the injection parameter target value of each channel is set (such as high molecular weight, low injection pressure for high permeability formation), which can ensure that the injection scheme matches the characteristics of different formations from the initial stage, laying a foundation for subsequent precise injection, and avoiding the imbalance of injection caused by the blindness of parameter setting in traditional injection methods.

[0188] By independently adjusting the rotating speed of the fan blades in the three channels through the multi-quality supercharger, the polymer mother liquor is treated into three solutions with different molecular weights and injection pressures, realizing the "customization" treatment of polymer solutions. This treatment method can make high-permeability layers obtain high-molecular-weight, low-pressure solutions to avoid injection breakthrough, and medium and low-permeability layers obtain suitable solutions to improve injection capacity, accurately match the molecular weight of the polymer with the permeability of the formation, and solve the problem that the polymer solution in the traditional technology cannot adapt to different permeability formations.

[0189] The layered injection separately injects solutions with different properties into corresponding formations through three independent channels, realizes independent injection of each layer, avoids interlayer interference, and ensures that each layer receives the injection liquid according to the preset scheme.

[0190] The real-time monitoring and control system collects data such as flow rate and pressure, and adjusts according to the deviation of the data from the preset parameters (such as adjusting the valve opening, fan blade speed, etc.), which can correct the deviation in the injection process in time. For example, when the pressure exceeds the upper limit, it is automatically adjusted to reduce the pressure, ensuring the stability of the injection process, solving the problem of complex traditional testing process and untimely regulation, and improving the efficiency of layered water allocation.

[0191] According to the dynamic changes of the formation permeability, the target parameters are updated (such as adjusting the parameters every 30 days according to the production fluid profile data), so that the injection scheme can adapt to the long-term changes of the oil reservoir. This dynamic adjustment mechanism ensures that the injection process is always optimally matched with the formation state, avoids the decline of injection effect caused by changes in the oil reservoir, maintains efficient oil displacement efficiency in the long term, and further improves the recovery efficiency.

[0192] When the flow rate of a channel is continuously lower than the target value and the pressure rises, a hierarchical response is performed (valve adjustment first, then fan blade speed adjustment, emergency shutdown above the threshold), which can quickly respond to abnormal situations in the injection process, avoid equipment damage or formation damage, ensure the safety and reliability of the injection system, and reduce production risk and maintenance cost.

[0193] Finally, it should be noted that the above-described preferred embodiments of the present application are not intended to limit the present application, and although the present application 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 modification, equivalent substitution, improvement, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An oilfield polymer concentric independent three-channel precision injection device, characterized in that: Comprise: (a) concentric three-channel pipe column: from inside to outside, the center tube (4), the middle tube (5) and the outer tube (6) are sequentially sleeved to form three independent fluid channels: Pipe column first channel: the inner cavity of the center tube (4); Pipe column second channel: the annular space between the center tube (4) and the middle tube (5); Pipe column third channel: the annular space between the middle tube (5) and the outer tube (6); (b) separate quality booster: arranged at the wellhead, comprising three independent channels, each channel is provided with a fan blade (314) with adjustable rotating speed, used for adjusting the molecular weight and injection pressure of the polymer solution according to the permeability of the target formation: The separate quality booster first channel outputs the polymer solution with high molecular weight and low injection pressure to the pipe column third channel; The separate quality booster second channel outputs the polymer solution with medium molecular weight and medium injection pressure to the pipe column second channel; The separate quality booster third channel outputs the polymer solution with low molecular weight and high injection pressure to the pipe column first channel; (c) monitoring and control system: comprising: Pressure sensors (2, 210, 214, 218) and flow meters (211, 215, 219) arranged at the wellhead of each fluid channel; Control system connected with the pressure sensors (2, 210, 214, 218), flow meters (211, 215, 219) and the separate quality booster, used for adjusting the rotating speed of the fan blade and the injection parameters of each channel according to the preset parameters.

2. The oilfield polymer concentric independent three-channel precise injection device according to claim 1, characterized in that: The rotating speed of the fan blade (314) of the separate quality booster is driven by a servo motor (34), and the power supply system of the servo motor (34) comprises a solar panel (31) and an energy storage battery (32).

3. The oilfield polymer concentric independent three-channel precise injection device according to claim 2, characterized in that: The end of the concentric three-channel pipe column is connected with a proportioning injector (11) and packers (8, 9, 10) for isolating each target formation.

4. The oilfield polymer concentric independent three-channel precise injection device according to claim 3, characterized in that: The center tube (4), the middle tube (5) and the outer tube (6) are made of corrosion-resistant alloy material, and the inner wall is treated by smoothing.

5. A method of oilfield polymer concentric independent three channel precision injection, based on the device of any one of claims 1-4, characterized in that, Comprise the following steps: (a) parameter presetting: according to the permeability difference of the target formation, set the target value of the injection parameters of each channel, including: The target parameters of the pipe column third channel corresponding to the high permeability formation: high molecular weight, low injection pressure; The target parameters of the pipe column second channel corresponding to the medium permeability formation: medium molecular weight, medium injection pressure; The target parameters of the pipe column first channel corresponding to the low permeability formation: low molecular weight, high injection pressure; (b) solution separate quality treatment: input the polymer mother liquor into the separate quality booster, and independently adjust the rotating speed of the fan blade (314) in the three channels: The fan blade of the separate quality booster first channel keeps low speed or stops rotating, and outputs the solution with high molecular weight and low injection pressure to the annular space between the middle tube (5) and the outer tube (6); The fan blade of the separate quality booster second channel operates at medium speed, and outputs the solution with medium molecular weight and medium injection pressure to the annular space between the center tube (4) and the middle tube (5); The fan blade of the separate quality booster third channel operates at high speed, and outputs the solution with low molecular weight and high injection pressure to the inner cavity of the center tube (4); (c) separate layer injection and real-time control: Collect the flow data and pressure data of each channel in real time through the monitoring and control system; The control system compares the collected data with the target parameters preset in step (a): If the flow rate deviates from the target value, adjust the valve opening of the corresponding channel; If the molecular weight deviates from the target value, adjust the corresponding fan speed of the molecular weight booster; If the injection pressure deviates from the target value, adjust the valve opening and fan speed synchronously; (d) Dynamic matching of the formation: through the closed-loop control of step (c), the molecular weight and injection pressure of the polymer solution output by each channel continuously match the permeability characteristics of the corresponding formation.

6. The method of claim 5, wherein the method is a concentric independent three- channel precise injection method for oilfield polymer. In step (c), when the pressure of a certain channel exceeds the preset upper limit, automatically increase the valve opening of the channel and reduce the corresponding fan speed; when the pressure is lower than the preset lower limit, reduce the valve opening and increase the fan speed.

7. The method of claim 6, wherein the method is a concentric independent three- channel precise injection method for oilfield polymer. In step (b), the fan speed adjustment range of the molecular weight booster is 1000-3000 rpm, and it satisfies: The fan speed of the first channel of the molecular weight booster is ≤1500 rpm, which makes the decrease of the molecular weight of the polymer ≤10%; The fan speed of the second channel of the molecular weight booster is 1500-2500 rpm, which makes the decrease of the molecular weight of the polymer 10%-30%; The fan speed of the third channel of the molecular weight booster is ≥2500 rpm, which makes the decrease of the molecular weight of the polymer ≥30%.

8. The method of claim 5, wherein the method is a concentric independent three- channel precise injection method for oilfield polymer. In step (c), the basis for determining the deviation of the molecular weight from the target value is: Real-time monitoring of the viscosity of the solution at the outlet of the molecular weight booster; Through the preset viscosity-molecular weight corresponding relationship curve, the actual molecular weight is calculated; If the deviation between the actual molecular weight and the target molecular weight exceeds ±5%, adjust the corresponding fan speed.

9. The method of claim 5, wherein the method is a concentric independent three- channel precise injection method for oilfield polymer. In step (c), when the flow rate of a certain channel continuously falls below the target value and the pressure rises, perform a staged response: First, increase the valve opening of the channel to the maximum allowed value; If the flow rate still does not meet the standard, further increase the corresponding fan speed to reduce the molecular weight; If the pressure exceeds the safety threshold, trigger an emergency injection stop.

10. The method of claim 5, wherein the method is a concentric independent three- channel precise injection method for oilfield polymer. In step (d), update the target parameters according to the dynamic changes of the formation permeability, including: Obtain the liquid production profile data of each interval every 30 days; If the liquid absorption ratio of a certain interval changes by more than ±15%, reset the molecular weight and pressure target values of the corresponding channel of the layer.

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