Intelligent submersible screw pump system based on multi-energy cooperative power supply and control method

Abstract

The invention relates to the technical field of oil field oil extraction equipment, in particular to an intelligent submersible screw pump system integrating photovoltaic power, wind power, energy storage and standby diesel power generation in a cooperative mode and a control method of the intelligent submersible screw pump system, and is suitable for remote oil wells or green low-carbon demonstration oil fields without power grid coverage. A new energy submersible screw pump system for an off-grid oil field is powered by a photovoltaic, wind power, energy storage and diesel standby four-source micro-grid, and energy scheduling of new energy priority-energy storage supplement-diesel guarantee is achieved through an intelligent micro-grid controller. The bidirectional frequency converter adjusts the rotating speed of the submersible screw pump in a closed-loop mode in real time according to underground pressure, so that the liquid level of an oil well is kept at a preset value, the underground flowing pressure is optimized, the liquid supply capacity of the oil well is improved, and meanwhile it is guaranteed that the submersible screw pump cannot be burnt due to liquid shortage.

Description

Technical Field

[0001] This invention relates to the field of oilfield production equipment technology, and in particular to an intelligent submersible screw pump system and its control method that integrates photovoltaic, wind power, energy storage and backup diesel power generation, applicable to remote oil wells or green and low-carbon demonstration oilfields without power grid coverage. Background Technology

[0002] Traditional oil pumping unit lifting systems have a dynamically sealed wellhead, posing a risk of oil leakage. They also have many moving parts on the ground, making fully automatic start-up and shutdown highly risky. Submersible screw pumps, a new type of rodless lifting device, have a fully sealed wellhead and no moving parts on the ground, making them safe and environmentally friendly, and enabling unattended operation at the well site.

[0003] However, traditional submersible screw pumps have the following problems:

[0004] 1. Relying on the power grid or diesel generators for power supply, the cost of powering remote oil wells is high.

[0005] 2. Bottlenecks exist in the application of new energy: First, the fluctuation of wind and solar resources is large, and direct drive motors are prone to cause unstable screw pump speed, affecting oil pumping efficiency; Second, there is a lack of intelligent control strategies that dynamically match the oilfield load. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides an intelligent submersible screw pump system and control method based on multi-energy collaborative power supply. It integrates photovoltaic, wind power, energy storage, and backup diesel power generation, solving the problems of traditional submersible screw pumps relying on the power grid or diesel generators for power supply and the high cost of power supply to remote oil wells. At the same time, it uses an intelligent microgrid controller, bidirectional frequency converter, and well condition monitoring sensors to convert the unstable DC power from new energy sources into AC power with adjustable frequency. Based on the new energy output prediction, energy storage charge status, and downhole operating conditions, it formulates energy priority scheduling strategies and submersible screw pump optimized operation strategies in real time.

[0008] (II) Technical Solution

[0009] To address the aforementioned problems, this invention provides an intelligent submersible screw pump system and control method based on multi-energy collaborative power supply, comprising: a photovoltaic power generation unit; a wind power generation unit; an energy storage unit; a backup diesel power generation unit; an intelligent microgrid controller; a bidirectional frequency converter; a downhole electric heating device; and a submersible screw pump oil production device.

[0010] Preferably, the photovoltaic power generation unit consists of a photovoltaic panel and a DC / DC converter, connected to the input terminal of the intelligent microgrid controller. It primarily generates electricity from solar energy and outputs stable direct current, providing a stable power supply for the submersible screw pump oil extraction unit and the energy storage unit.

[0011] Preferably, the wind power generation unit consists of a wind turbine and an AC / DC rectifier, which is connected to the input terminal of the intelligent microgrid controller. It mainly realizes the generation of wind energy and rectifies the unstable AC power into stable DC power for output, providing a stable power supply for the submersible screw pump oil extraction device and the energy storage unit.

[0012] Preferably, the energy storage unit consists of a lithium iron phosphate battery and a supercapacitor, and is connected to the output of the intelligent microgrid controller. Its main function is to store excess electricity to ensure that the submersible screw pump oil extraction device can be powered when the wind turbine unit and photovoltaic unit cannot work due to weather conditions.

[0013] Preferably, the intelligent microgrid controller is used to formulate energy priority scheduling strategies in real time based on new energy output forecasts, energy storage charge status and downhole operating conditions to achieve energy scheduling;

[0014] Preferably, the bidirectional frequency converter connects the intelligent microgrid controller and the submersible screw pump oil extraction device to convert unstable DC power into AC power with adjustable frequency.

[0015] Preferably, the well condition monitoring sensor is connected to the bidirectional frequency converter of the submersible screw pump oil production unit, and its main function is to monitor downhole temperature, submersion degree and downhole flow rate in real time, so as to provide data support for the optimized operation of the submersible screw pump oil production unit.

[0016] Preferably, the downhole electric heating device is connected to the intelligent microgrid controller. When the energy storage unit is full, the remaining electricity is used to clean and prevent wax blockage in the oil well through the downhole electric heating device.

[0017] Preferably, the diesel generator unit is connected to the input terminal of the smart microgrid controller, mainly to provide temporary energy for the submersible screw pump oil extraction device when the photovoltaic power generation unit and the wind power generation unit cannot work and the energy storage unit runs out of power.

[0018] (III) Beneficial Effects

[0019] Compared with existing technologies, the intelligent submersible screw pump system and control method based on multi-energy coordinated power supply provided by this invention have the following significant advantages:

[0020] 1. In terms of energy utilization and environmental protection:

[0021] It has achieved an extremely high fossil energy substitution rate and carbon emission reduction: Through a multi-level energy dispatch strategy of "wind and solar priority, energy storage regulation, and diesel backup", the system can rely entirely on renewable energy during most operating periods, effectively replacing more than 90% of traditional diesel or grid consumption, significantly reducing carbon emissions from oil extraction operations, with an average annual carbon dioxide emission reduction of tens of tons per well site, actively responding to the national "dual carbon" strategy and the requirements for green mine construction.

[0022] 2. Regarding system reliability and economy:

[0023] It ensures extremely high reliability for continuous and stable production in off-grid oilfields: the hybrid energy storage system (lithium battery + supercapacitor) and the backup diesel system form a multi-level energy guarantee. The intelligent microgrid controller can smooth the second-level and minute-level fluctuations in wind and solar power, and control the speed fluctuation of the submersible screw pump within ±2% of the rated value. This effectively avoids problems such as overheating, delamination, and premature wear of the stator rubber caused by sudden speed changes, thus ensuring the continuity of production.

[0024] Significantly reduces total lifecycle operating costs: Despite high initial equipment investment, the system's payback period can be shortened to 3-5 years thanks to extremely low fuel and maintenance costs.

[0025] 3. In terms of mining efficiency and intelligentization:

[0026] This invention enables intelligent and unmanned operation of oilfield production: Its pioneering adaptive frequency conversion control algorithm based on real-time downhole pressure (ΔP) dynamically optimizes rotational speed to match well conditions, eliminating the need for manual intervention. The remote monitoring platform allows engineers to centrally manage dispersed well sites, significantly reducing labor intensity and safety hazards, and providing crucial technical equipment support for building "unmanned oilfields" and "intelligent oilfields."

[0027] 4. In terms of technological integration and innovation:

[0028] Successfully solved the technical bottleneck of multi-energy synergy and precise load matching: This invention is not a simple superposition of new energy and traditional equipment, but a deep integration of technologies to convert unstable new energy input into stable, reliable power output that is precisely matched to complex downhole conditions. It has overcome the core problem of green and low-carbon development in off-grid oilfields and provided a brand-new solution for the economic and effective development of marginal oilfields and remote blocks. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the intelligent submersible screw pump system and control method based on multi-energy collaborative power supply of the present invention.

[0030] The components include: 1. Photovoltaic power generation unit; 2. Wind power generation unit; 3. Energy storage unit; 4. Backup diesel power generation unit; 5. Intelligent microgrid controller; 6. Bidirectional frequency converter; 7. Well condition monitoring sensor; 8. Downhole electric heating device; 9. Submersible screw pump oil production device; and 10. Power cable.

[0031] In the picture:

[0032] (1) Solid line (——): indicates the path of electrical energy transmission.

[0033] (2) Connection point This indicates the electrical connection between devices.

[0034] (3) Double arrow (<-->): indicates bidirectional charging and discharging of electrical energy between energy storage unit 3 and smart microgrid controller 5.

[0035] (4) Dashed arrow (-->): indicates the transmission and feedback path of data signals, forming a closed-loop control. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "top", and "bottom" are based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of this invention and to simplify the description. It is not intended to indicate or imply that the component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0038] like Figure 1As shown, this embodiment provides an intelligent submersible screw pump system and control method based on multi-energy collaborative power supply. Specifically, it includes: a photovoltaic power generation unit 1, consisting of a photovoltaic panel and a DC / DC converter, connected to the input terminal of the intelligent microgrid controller 5, primarily generating solar energy and outputting stable DC power to provide a stable power supply for the submersible screw pump oil extraction device 9 and the energy storage unit 3; a wind power generation unit 2, consisting of a wind turbine and an AC / DC rectifier, connected to the input terminal of the intelligent microgrid controller 5, primarily generating wind energy and rectifying unstable AC power into stable DC power for output, providing a stable power supply for the submersible screw pump oil extraction device 9 and the energy storage unit 3; and an energy storage unit 3, consisting of a lithium iron phosphate battery and a supercapacitor, connected to the output terminal of the intelligent microgrid controller 5, whose main function is to store excess electricity to ensure power supply during weather-related emergencies. In the event that the wind power generation unit 2 and the photovoltaic power generation unit 1 are unable to operate, the submersible screw pump oil production device 9 is provided with electrical energy. The intelligent microgrid controller is used to formulate an energy priority scheduling strategy in real time based on the output prediction of the photovoltaic power generation unit 1 and the wind power generation unit 2, the status of the energy storage unit 3, and the downhole operating conditions to achieve energy scheduling. The bidirectional frequency converter 6 is connected to the intelligent microgrid controller 5 and the submersible screw pump oil production device 9 to convert unstable DC power into AC power with adjustable frequency to provide driving power for the submersible screw pump oil production device 9. The well condition monitoring sensor 7 is installed downhole to monitor downhole pressure, temperature, and flow rate in real time to provide the bidirectional frequency converter 6 with reference data for optimized operation of the submersible screw pump oil production device 9. The downhole electric heating device 8 is connected to the intelligent microgrid controller 5 and placed downhole to use residual electricity to clean and prevent wax from the oil well.

[0039] The specific operation process is as follows:

[0040] Step 1: According to the work requirements, place the photovoltaic power generation unit 1, wind power generation unit 2, energy storage unit 3, and backup diesel power generation unit 4 in the optimal positions at the well site, and connect them to the input terminal of the intelligent microgrid controller 5 to form a ground intelligent power supply microgrid system.

[0041] Step 2: Arrange the well condition monitoring sensor 7, downhole electric heating device 8, power cable 10 and screw pump oil production device 9 downhole to form a downhole artificial lifting system and data acquisition system, so as to realize the function of collecting well fluid and downhole operating data to the surface.

[0042] Step 3: Connect one end of the power cable 10 to the screw pump oil production unit 9, and the other end to the output terminal of the bidirectional frequency converter 6. Connect the input terminal of the bidirectional frequency converter 6 to the output terminal of the intelligent microgrid controller 5. Connect the well condition monitoring sensor 7 to the motor of the screw pump oil production unit 9. Use carrier wave technology to transmit the collected downhole operating parameters to the bidirectional frequency converter 6. This realizes the connection between the surface intelligent power supply microgrid system and the downhole acquisition system.

[0043] Step 4: Connect the downhole electric heating device 8 to the output terminal of the intelligent microgrid controller 5. This establishes the connection between the surface intelligent power supply microgrid and the downhole heating system.

[0044] Step 5: The intelligent power supply microgrid system starts working, continuously transmitting the electrical energy converted from green energy to the downhole submersible screw pump production device 9 via power cable 10, realizing the artificial lifting of well fluid; at the same time, the well condition monitoring sensor 7 transmits downhole operating data to the bidirectional frequency converter 6 in real time, and adjusts the motor speed of the screw pump production device 9 to the economical speed range through the bidirectional frequency converter 6, while controlling the well submersion degree at the preset value, forming a closed-loop control.

[0045] Step Six: The intelligent microgrid controller 5 allocates surplus electricity to the energy storage unit 3 and the downhole electric heating device 8 based on real-time well conditions, effectively storing the surplus electricity and using the downhole electric heating device 8 to clean and prevent wax from the oil well. The backup diesel generator unit 4 is ready to intervene at any time in the event of a shortage of green energy.

[0046] This invention utilizes a multi-energy coordinated power supply to drive a submersible screw pump for artificial lift, while also taking into account the utilization of surplus electricity. It employs electric heating to overcome the technical drawback of wax buildup in submersible screw pumps. Furthermore, the closed-loop control system not only effectively reduces the energy consumption of the submersible screw pump but also extends the pump inspection cycle. It is suitable not only for artificial lift in conventional oil reservoirs but also for unconventional oil reservoirs such as heavy oil and shale oil, showing broad application prospects.

[0047] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A submersible screw pump system for new energy power supply, characterized in that, Including: a) Photovoltaic power generation unit; b) Wind power generation unit; c) Energy storage unit, composed of lithium iron phosphate battery and supercapacitor; d) Standby diesel power generation unit; e) Intelligent microgrid controller, used to formulate an energy priority scheduling strategy in real time according to new energy output prediction, energy storage state of charge, and downhole working conditions; f) Bidirectional frequency converter, connecting the intelligent microgrid controller and the progressing cavity pump motor, used to convert unstable direct current into alternating current with adjustable frequency; g) Well condition monitoring sensors, at least including downhole pressure, temperature, and flow sensors, whose output signals are used to closed-loop adjust the output frequency of the frequency converter; h) Downhole electric heating device. The progressing cavity pump belongs to rodless lifting, and wax is likely to form in the oil well. It is mainly used for wax removal and prevention in the oil well.

2. The system according to claim 1, characterized in that, The frequency converter compares the real-time fluid level value P with the preset threshold P0. When P > P0, the motor speed is automatically increased by Δn, Δn = k·(P–P0). When P < P0, the motor speed is automatically decreased by Δn, Δn = k·(P0–P), where k is an adjustment coefficient determined by exploring the variation law of motor speed with fluid level under different well conditions.

3. A control method for the system as described in claim 1 or 2, characterized in that, Including the following steps: a) Obtain the predicted data of illumination and wind speed for the next 24 hours; b) Generate a pre-scheduling plan based on the oil well production capacity - energy consumption model and determine the energy storage charge and discharge curve; c) Collect the downhole pressure in real time and calculate the priority value Qp of liquid production; ​ 4. The method according to claim 3, characterized in that, ​ 5. The method according to claim 3 or 4, characterized in that, ​ 6. The method according to claim 5, characterized in that, ​ 7. The method according to claims 5 and 6, characterized in that... ​ 8. The method according to claims 6 and 7, characterized in that... ​

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