Intelligent downhole wax removal device and method based on online fluid viscosity monitoring

Abstract

The application discloses a kind of wellbore intelligent wax removal device and method based on online fluid viscosity monitoring, belong to petroleum and natural gas exploitation technical field, wellbore intelligent wax removal device includes upper tubing, lower tubing and short circuit, torsional vibration viscosity sensor and temperature sensor on short circuit are connected with data processing center, lower tubing and short circuit are wrapped with heating insulation layer, data processing center and heating insulation layer are connected with ground power supply system;Utilize torsional vibration viscosity sensor and temperature sensor to obtain downhole fluid viscosity and temperature data, provide temperature reference for the regulation and control of heating insulation layer.The application utilizes short circuit to be installed between any two oil pipes, can flexibly measure the fluid viscosity and temperature at any position in the well, and dynamically adjusts the heating parameters according to the real-time working condition in the well, starts and stops the heating function, realizes accurate wax removal, improves the intelligence and energy saving of downhole wax removal, forms automatic closed-loop operation, without manual intervention, improves the continuous production efficiency of oil well.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, and specifically relates to a downhole intelligent dewaxing device and method based on online fluid viscosity monitoring. Background Technology

[0002] In oil and gas extraction, wax crystal deposition and wax buildup are common problems in downhole tubing, sucker rods, and fluid transport channels. Accumulated wax layers reduce the flow cross-section, increase flow resistance, leading to decreased well productivity, increased lift energy consumption, and potentially causing wellbore blockage, rod and tubing jamming, and other malfunctions. In severe cases, well shutdown is necessary, significantly impacting continuous production and operational safety. Therefore, downhole wax deposition control is a critical challenge in oil and gas wellbore operations, especially for high-viscosity crude oil extraction, where wax deposition poses a more significant constraint.

[0003] Among existing downhole dewaxing technologies, tubing electric heating dewaxing is widely used due to its significant advantages: First, it is not limited by well depth and can solve the problem of high-viscosity crude oil entering the pump, achieving preheating of crude oil before pumping to improve its fluidity; second, it does not require modification of the original oil production process of ordinary oil wells, facilitating oil production management and reducing process modification costs; third, the heating effect is controllable, ensuring smooth crude oil lifting, and only increasing power is needed when the wellhead temperature needs to be increased, making it convenient to operate and highly adaptable. Based on this, this technology has become the mainstream dewaxing method in scenarios such as high-viscosity crude oil wells and deep wells. However, existing tubing electric heating dewaxing devices and systems have shortcomings in intelligence and precision. The core problem is the lack of an online real-time monitoring and feedback mechanism for downhole fluid viscosity, resulting in the heating process not being able to accurately match the actual waxing state. Fluid viscosity is the core parameter characterizing the degree of waxing, and changes in wax crystal deposition are directly reflected in viscosity rises and falls. However, existing devices mostly use fixed power and fixed temperature for coarse control, and cannot grasp the waxing and dewaxing situation in real time through viscosity parameters, only relying on experience to preset heating parameters.

[0004] Currently, some technologies attempt to determine wax deposition using indirect parameters such as temperature and pressure. However, these parameters are easily affected by factors such as downhole flow rate, formation pressure, and crude oil composition, resulting in poor accuracy and failing to provide a reliable basis for control. This makes it difficult to reasonably control parameters even for existing equipment with advantages such as adjustable power: insufficient power leads to incomplete dewaxing and recurring problems, making it difficult to fully utilize its adaptability to high-viscosity crude oil; blindly increasing heating power, while achieving dewaxing, wastes energy and may cause problems such as crude oil cracking and formation damage, shortening the lifespan of heating elements and contradicting its original intention of convenience and efficiency.

[0005] In summary, while existing tubing electric heating dewaxing technology offers advantages such as being unrestricted by well depth, not requiring modifications to existing processes, and offering adjustable power, the lack of online fluid viscosity monitoring leads to inaccurate wax deposition detection and coarse control, failing to balance dewaxing effectiveness, energy efficiency, and operational safety. Therefore, combining online fluid viscosity detection with tubing electric heating technology to develop intelligent dewaxing devices and systems, enabling real-time wax deposition detection and adaptive heating control, and addressing these technological shortcomings, has become an urgent need in the oil and gas extraction sector. Summary of the Invention

[0006] The purpose of this invention is to provide an intelligent downhole dewaxing device and method based on online fluid viscosity monitoring, aiming to solve the technical problems in existing tubing electric heating dewaxing technology, such as lack of online fluid viscosity monitoring, inaccurate perception of wax deposition status, crude heating control, and inability to balance dewaxing effect, energy efficiency and downhole operation safety.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A downhole intelligent dewaxing device based on online fluid viscosity monitoring, the downhole intelligent dewaxing device includes a tube-shaped short joint, the short joint is equipped with a torsional vibration viscosity sensor and a temperature sensor for collecting the viscosity of the fluid in the tubing and the temperature around the tubing, the torsional vibration viscosity sensor and the temperature sensor are both connected to a data processing center.

[0009] The oil pipe has a split structure, including an upper oil pipe and a lower oil pipe. The upper oil pipe and the lower oil pipe are respectively connected to the upper and lower openings of the short connection. The lower oil pipe and the middle and lower part of the short connection are wrapped with a heating and insulation layer. The data processing center and the heating and insulation layer are both connected to the ground power supply system.

[0010] The tubing is installed inside the casing, and an insulating centralizer is installed in the annulus between the tubing and the casing. The casing is installed inside the wellbore, and a sucker rod is installed inside the tubing. A sucker rod pump is installed at the lower end of the sucker rod.

[0011] The data processing center controls the heating or heat preservation of the electric heating wire based on the temperature data collected by the temperature sensor, and controls the start and stop of the electric heating wire based on the fluid viscosity collected by the torsional vibration viscosity sensor, thereby realizing dewaxing regulation.

[0012] Furthermore, an electric heating wire is embedded in the heating and insulation layer, and the wiring terminals of the electric heating wire are electrically connected to the electrical control cabinet via a power supply cable. The electrical control cabinet is electrically connected to the ground power supply system.

[0013] Furthermore, a bypass channel is provided within the side wall of the short connector, the bypass channel extending upwards and outwards to the top surface of the short connector. An upper horizontal channel, communicating with a monitoring hole on the upper oil pipe, is provided on the upper side of the bypass channel, and a lower horizontal channel is provided on the lower side of the bypass channel, facing the gap between the upper and lower oil pipes. The torsional vibration viscosity sensor is located in the upper part of the bypass channel, with its probe corresponding to the upper horizontal channel. An electric valve is located in the middle of the bypass channel. The temperature sensor is located on the side of the bypass channel and at the top of the short connector.

[0014] The torsional vibration viscosity sensor, temperature sensor, and electric valve are all connected to the ground signal receiving equipment via data cables, and the ground signal receiving equipment is connected to the data processing center.

[0015] Furthermore, the data processing center, electrical control cabinet, and ground power supply system are all located on the ground, with the ground power supply system providing power to the data processing center, electrical control cabinet, and heating insulation layer.

[0016] Furthermore, the lower part of the torsional vibration viscosity sensor is connected to the orifice of the bypass channel via a base. The lower end of the base is connected to the pendulum via a torsion tube. Two sets of piezoelectric ceramic elements are placed inside the pendulum: one set is a driving piezoelectric ceramic for driving the pendulum, and the other set is a feedback piezoelectric ceramic, which can measure and control the rotation of the pendulum through feedback signals. A flow tube is provided outside the torsion tube and the pendulum, and the flow tube is connected to the frustum-shaped lower part of the base.

[0017] Furthermore, the torsional vibration viscosity sensor employs the core principle of torsional vibration-phase difference detection, driving a piezoelectric ceramic to drive a pendulum at its natural frequency. Resonant vibration occurs when downhole fluid flows through the sucker rod, generating viscous damping on the pendulum; the feedback piezoelectric ceramic captures two sets of resonant frequencies corresponding to a ±45° phase difference. , Calculate the resonant frequency difference Combining downhole operating condition interference compensation, the fluid viscosity is accurately calculated through formula derivation. The calculation formula is as follows:

[0018]

[0019] In the formula: : Downhole fluid dynamic viscosity, Pa·s;

[0020] The resonant frequency corresponding to a +45° phase difference, in Hz;

[0021] The resonant frequency corresponding to a -45° phase difference, in Hz;

[0022] ±45° phase difference corresponds to the resonant frequency difference, in Hz;

[0023] Torsional vibration viscosity sensor: pendulum moment of inertia, kg·m²;

[0024] : Inner radius of the cylindrical flow tube of the torsional vibration viscosity sensor, in meters;

[0025] L: Effective length of the cylindrical flow tube, in meters;

[0026] The uniform gap between the flow tube and the pendulum, in meters (m).

[0027] : Fluid velocity inside the oil pipe, m / s;

[0028] Wear amount of coating on flow tube surface, μm;

[0029] : The natural frequency of the pendulum, Hz;

[0030] Flow velocity compensation coefficient, calibrated through downhole multi-condition experiments, dimensionless;

[0031] Coating wear compensation coefficient, calibrated through downhole multi-condition experiments, dimensionless;

[0032] The real-time fluid viscosity value obtained by the above formula The data is transmitted in real time to the ground signal receiving equipment via data cable and synchronized to the data processing center. The data processing center completes the reception, analysis, storage and status monitoring of the downhole data, and synchronizes the real-time viscosity value to the electrical control cabinet.

[0033] Critical viscosity threshold of wax plugging inside electrical control cabinet After receiving the fluid viscosity value, it automatically compares and judges it with the threshold, and realizes power supply control for the downhole heating and insulation layer through the power supply cable: when the real-time fluid viscosity value... Reaching or exceeding the critical viscosity threshold for wax blockage At that time, the electrical control cabinet outputs a power supply signal to the heating and insulation layer through the power supply cable to heat and reduce the viscosity of the downhole fluid and dissolve the wax; when the real-time viscosity value Reduced to the critical viscosity threshold of wax blockage When the following occurs, the electrical control cabinet immediately cuts off the power output of the power supply cable, the heating insulation layer stops heating, and the dewaxing control is completed.

[0034] Furthermore, an insulating sucker rod is provided on the upper exterior of the sucker rod to ensure insulation between the oil pipe and the sucker rod.

[0035] Furthermore, the lower oil pipe and the middle and lower part of the short connection are filled with heat-insulating materials between them and the corresponding heating and insulation layers.

[0036] This invention also provides a downhole intelligent dewaxing method based on online fluid viscosity monitoring, comprising the following steps:

[0037] First, assemble the above-mentioned downhole intelligent dewaxing device, and simultaneously install the torsional vibration viscosity sensor and temperature sensor at the designated position above the short connector to ensure that the two can accurately collect fluid viscosity and temperature data of the target layer. Then, place the tubing and the short connector with heating and insulation layer into the target monitoring position in the wellbore in sequence.

[0038] Then, connect the main power supply of the electrical control cabinet, turn on the power switch, set the heating and insulation parameters, start the heating function, and the heating insulation layer enters normal working state; the electrical control cabinet automatically receives real-time temperature data transmitted by the temperature sensor and viscosity data transmitted by the torsional vibration viscosity sensor, and controls the start and stop of the electric heating wire in combination with the preset parameters. When the temperature of the target object reaches the set insulation temperature, the electric heating wire stops heating or switches to low-temperature insulation mode; when the temperature is lower than the insulation threshold, the electric heating wire automatically starts to supplement heat to maintain temperature stability;

[0039] When heating and insulation are no longer needed, first turn off the heating function of the heating and insulation layer through the electrical control cabinet, keep the power supply connected, and wait for the temperature of the target object to drop naturally to a safe temperature before turning off the main power supply of the electrical control cabinet and disconnecting the power supply of the ground power supply system. During this process, the temperature sensor continuously collects temperature data and transmits it to the ground to provide a basis for judging whether a safe temperature has been reached.

[0040] The technological advancements achieved by this invention compared to existing technologies are as follows:

[0041] This invention connects the upper and lower tubing via a short-circuit connection and utilizes torsional vibration viscosity and temperature sensors on the short-circuit to acquire real-time fluid viscosity and temperature data. This provides a temperature reference for regulating the heating and insulation layer, intelligently adjusting the heating state, and improving the intelligence and energy efficiency of downhole dewaxing. By installing the short-circuit between any two tubing lines, this invention can flexibly measure fluid viscosity and temperature at any location downhole and dynamically adjust heating parameters and start / stop heating functions based on real-time downhole conditions, achieving precise dewaxing. This invention integrates monitoring, heating, and control into a single automated closed-loop operation, requiring no manual intervention, reducing well shutdown frequency, improving continuous well production efficiency, and simultaneously strengthening insulation and sealing design to reduce downhole failure risks. Attached Figure Description

[0042] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0043] In the attached diagram:

[0044] Figure 1 This is a schematic diagram of the structure of a downhole intelligent dewaxing device based on online fluid viscosity monitoring, provided in an embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram of a short-circuit connection between the upper and lower oil pipes in an embodiment of the present invention;

[0046] Figure 3 This is a cross-sectional schematic diagram of the oil pipe, short connector, and heating insulation layer in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the installation of the torsional vibration viscosity sensor, temperature sensor, and electric valve on the short circuit in an embodiment of the present invention;

[0048] Figure 5 This is a side view of the torsional vibration viscosity sensor, temperature sensor, and electric valve installed at the short circuit in an embodiment of the present invention.

[0049] Figure 6 This is a cross-sectional schematic diagram of the torsional vibration viscosity sensor and electric valve installed in the bypass channel in an embodiment of the present invention;

[0050] Figure 7 for Figure 6 A partial enlarged view of the torsional vibration viscosity sensor and electric valve;

[0051] Figure 8 This is an external view of the temperature sensor in an embodiment of the present invention;

[0052] Figure 9 This is an external view of the electric valve in an embodiment of the present invention;

[0053] Figure 10 This is an external view of the torsional vibration viscosity sensor in an embodiment of the present invention.

[0054] In the picture:

[0055] 1-Upper tubing; 2-Insulated centralizer; 3-Casing; 4-Torsion vibration viscosity sensor; 5-Electric valve; 6-Electric heating wire; 7-Sucker rod; 8-Insulated sucker rod; 9-Short circuit; 10-Terminal; 11-Heating insulation layer; 12-Sucker pump; 13-Data cable; 14-Power supply cable; 15-Lower tubing; 16-Annulus; 17-Bypass channel; 18-Temperature sensor; 19-Upper horizontal channel; 20-Lower horizontal channel;

[0056] 41-Base; 42-Twist tube; 43-Piezoelectric ceramic element; 44-Pendulum; 45-Flow tube. Detailed Implementation

[0057] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. In the following detailed description of the invention, certain specific details are described in detail. However, those skilled in the art will fully understand the invention for any parts not described in detail.

[0058] Furthermore, those skilled in the art should understand that the accompanying drawings are provided only to illustrate the purpose, features, and advantages of the present invention, and are not actually drawn to scale.

[0059] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0060] like Figure 1 , 2 As shown in the figure, this invention provides a downhole intelligent dewaxing device based on online fluid viscosity monitoring. The device includes a tubular connector 9, a torsional vibration viscosity sensor 4, and a temperature sensor 18 for collecting the viscosity of the fluid inside the tubing and the temperature around the tubing. Both the torsional vibration viscosity sensor 4 and the temperature sensor 18 are connected to a data processing center. The torsional vibration viscosity sensor and the temperature sensor can be used to collect the downhole fluid viscosity and temperature in real time and transmit them synchronously to the surface data processing center.

[0061] The tubing has a split structure, including an upper tubing 1 and a lower tubing 15. The upper tubing 1 and the lower tubing 15 are tightly connected to the upper and lower openings of the short connector 9, respectively. The lower part of the lower tubing 15 and the lower part of the short connector 9 are wrapped with a heating and insulation layer 11. The data processing center and the heating and insulation layer 11 are both connected to the surface power supply system. The two ends of the short connector 9 are connected to the upper tubing 1 and the lower tubing 15 with a high-strength threaded structure, which is convenient for disassembly and assembly. It can be flexibly installed in any target well section according to the downhole monitoring and heating requirements, ensuring accurate collection of fluid viscosity and temperature data in key wax-deposited areas. At the same time, it provides a stable mounting carrier for electric valves, torsional vibration viscosity sensors, and temperature sensors, and takes into account both structural support and functional integration.

[0062] During installation, the aforementioned tubing is placed inside the casing 3, and an insulating centralizer 2 is provided between the tubing and the casing 3. The annular space 16 between the tubing and the casing 3 can serve as a space for cable laying and insulation isolation, ensuring that the tubing and the casing 3 maintain a set distance and achieve insulation isolation, avoiding short circuits or signal interference caused by contact between the two. The casing 3 is placed inside the wellbore, and a sucker rod 7 is installed inside the tubing. A sucker pump 12 is provided at the lower end of the sucker rod 7, and an insulating sucker rod 8 is installed on the upper exterior of the sucker rod 7 to further ensure the insulation performance between the tubing and the sucker rod 7, and to prevent current leakage and component corrosion.

[0063] In the specific production process, such as Figure 3 As shown, the heating and insulation layer 11 is embedded with an electric heating wire 6. The terminal 10 of the electric heating wire 6 is electrically connected to the electrical control cabinet on the ground through a power supply cable 14 passing through the annular space 16. The electrical control cabinet is electrically connected to the ground power supply system, and the power supply cable 14 has a branch connected to the ground. In specific manufacturing, ensure that the terminals of the power supply cable 14 and the terminal 10 are reliably connected, and perform insulation sealing treatment on the connection parts; tightly attach the heating and insulation layer to the target object, and fill the gaps between the electric heating wire and the corresponding short circuit and oil pipe parts with high-temperature resistant and insulating insulation material, and compact and fix it to ensure heating efficiency, insulation effect and structural stability, while avoiding temperature loss that affects the dewaxing effect. The power supply cable 14 provides AC power to the electric heating wire 6 for electric heating, which raises the temperature of the entire oil pipe and short circuit, forming a heat source; the electrical control cabinet can dynamically adjust the electrothermal conversion power according to the real-time temperature data transmitted by the temperature sensor and the viscosity data transmitted by the torsional vibration viscosity sensor to achieve the purpose of viscosity reduction and dewaxing, while avoiding excessive temperature that would cause energy waste or crude oil cracking.

[0064] In specific embodiments of the present invention, such as Figure 3-10 As shown, a bypass channel 17 is provided inside the side wall of the short-connector 9. The bypass channel 17 extends upwards and connects to the top surface of the short-connector 9. An upper horizontal channel 19, which connects to the monitoring hole on the upper tubing 1, is provided on the upper side of the bypass channel 17. A lower horizontal channel 20 is provided on the lower side of the bypass channel 17, and it is positioned towards the gap between the upper tubing 1 and the lower tubing 15. The torsional vibration viscosity sensor 4 is located on the upper part of the bypass channel 17, and its probe corresponds to the upper horizontal channel 19. The electric valve 5 is located in the middle of the bypass channel 17. The temperature sensor 18 is located on the side of the bypass channel 17 and on the top of the short-connector 9. The decision to activate the electric valve is based on the downhole fluid status. The downhole fluid status is determined by the surface data processing center by combining the viscosity data collected by the torsional vibration viscosity sensor and the temperature data collected by the temperature sensor, and then issuing start / stop commands.

[0065] During assembly, the torsional vibration viscosity sensor 4, temperature sensor 18, and electric valve 5 are all connected to the ground signal receiving equipment via data cable 13. This ground signal receiving equipment is connected to the data processing center, which analyzes and processes the data in real time, simultaneously acquiring the fluid viscosity and temperature parameters downhole. This provides data support for heating control and the start / stop of the electric valve. Simultaneously, the fluid viscosity and temperature data serve as the core basis for the ground data processing center to determine the wax deposition state and adjust heating parameters, ensuring precise matching between heating for wax removal and downhole temperature conditions.

[0066] In practical applications, the electric valve 5 serves as a downhole fluid diversion and control component. Its start / stop state is determined by the actual state of the downhole fluid, which is based on viscosity and temperature data fed back from the surface signal receiving equipment. When the fluid viscosity is too high, the risk of wax deposition increases, or the fluid flow state needs to be adjusted during the heating process, the electric valve 5 can be activated to open the bypass channel 17 to assist fluid flow and optimize the heating effect. After the fluid state returns to normal, the electric valve can be closed to maintain the normal tubing delivery path.

[0067] During the specific installation, such as Figure 1 As shown, the data processing center, electrical control cabinet and ground power supply system are all located on the ground. The ground power supply system provides power to the data processing center, electrical control cabinet and heating insulation layer 11.

[0068] As a preferred structure, such as Figure 7 As shown, the lower part of the torsional vibration viscosity sensor 4 is connected to the orifice of the bypass channel 17 via a base 41. The lower end of the base 41 is connected to the pendulum 44 via a torsion tube 42. Two sets of piezoelectric ceramic elements 43 are placed inside the pendulum 44: one set is a driving piezoelectric ceramic element used to drive the pendulum 44 to rotate; the other set is a feedback piezoelectric ceramic element that measures the pendulum's rotation angle, frequency, and other parameters in real time, and can accurately control the rotation of the pendulum 44 through feedback signals. A flow tube 45 is provided outside the torsion tube 42 and the pendulum 44. The flow tube 45 is connected to the lower frustum of the base 41, protecting the pendulum from mechanical damage. This torsional vibration viscosity sensor adopts a pendulum-type structure design, achieving coordinated driving and detection through two sets of piezoelectric ceramic elements. Based on the correlation between the pendulum's rotation characteristics and fluid viscosity, fluid viscosity data can be obtained through signal analysis, resulting in high detection accuracy and strong anti-interference capability. The torsional vibration viscosity sensor works in conjunction with the temperature sensor installed on the same side to synchronously collect fluid viscosity and temperature data at the same location downhole, ensuring data correlation and detection accuracy.

[0069] The torsional vibration viscosity sensor 4 adopts the core principle of torsional vibration-phase difference detection, driving the piezoelectric ceramic to drive the pendulum 44 at its natural frequency. Resonant vibration occurs when downhole fluid flows through sucker rod 7, generating viscous damping on pendulum 44; the feedback piezoelectric ceramic captures two sets of resonant frequencies corresponding to a ±45° phase difference. , Calculate the resonant frequency difference Combining downhole operating condition interference compensation, the fluid viscosity is accurately calculated through formula derivation. The calculation formula is as follows:

[0070]

[0071] In the formula: : Downhole fluid dynamic viscosity, Pa·s;

[0072] The resonant frequency corresponding to a +45° phase difference, in Hz;

[0073] The resonant frequency corresponding to a -45° phase difference, in Hz;

[0074] ±45° phase difference corresponds to the resonant frequency difference, in Hz;

[0075] Torsional vibration viscosity sensor: pendulum moment of inertia, kg·m²;

[0076] : Inner radius of the cylindrical flow tube of the torsional vibration viscosity sensor, in meters;

[0077] L: Effective length of the cylindrical flow tube, in meters;

[0078] The uniform gap between the flow tube and the pendulum, in meters (m).

[0079] : Fluid velocity inside the oil pipe, m / s;

[0080] Wear amount of coating on flow tube surface, μm;

[0081] : The natural frequency of the pendulum, Hz;

[0082] Flow velocity compensation coefficient, calibrated through downhole multi-condition experiments, dimensionless;

[0083] Coating wear compensation coefficient, calibrated through downhole multi-condition experiments, dimensionless;

[0084] The real-time fluid viscosity value obtained by the above formula Data is transmitted in real time to the ground signal receiving equipment via data cable 13 and synchronized to the data processing center. The data processing center completes the reception, analysis, storage and status monitoring of the downhole data, and synchronizes the real-time viscosity value to the electrical control cabinet.

[0085] Critical viscosity threshold of wax plugging inside electrical control cabinet After receiving the fluid viscosity value, it automatically compares and judges it with the threshold, and realizes power supply control for the downhole heating and insulation layer through the power supply cable: when the real-time fluid viscosity value... Reaching or exceeding the critical viscosity threshold for wax blockage At that time, the electrical control cabinet outputs a power supply signal to the heating and insulation layer through the power supply cable to heat and reduce the viscosity of the downhole fluid and dissolve the wax; when the real-time viscosity value Reduced to the critical viscosity threshold of wax blockage When the following occurs, the electrical control cabinet immediately cuts off the power output of the power supply cable, the heating insulation layer stops heating, and the dewaxing control is completed.

[0086] This invention also provides a downhole intelligent dewaxing method based on online fluid viscosity monitoring, comprising the following steps:

[0087] First, assemble the aforementioned downhole intelligent dewaxing device. Simultaneously install the torsional vibration viscosity sensor and temperature sensor at designated positions on the short connector. Place the tubing and the short connector with heating and insulation layer sequentially into the target monitoring position in the wellbore, ensuring accurate acquisition of fluid viscosity and temperature data for the target layer. Connect any two tubing sections using the short connector and install them at any downhole location as needed. Use the torsional vibration viscosity sensor and temperature sensor to collect fluid viscosity and temperature data for the target layer, achieving flexible monitoring and targeted dewaxing throughout the entire downhole section.

[0088] When installing the heating and insulation layer, ensure it fits tightly against the target object, with the electric heating wires connected to the corresponding short-circuit and oil pipe locations. Connect one end of the power cable to the wiring terminal of the heating and insulation layer, ensuring a reliable connection between the conductor end of the power cable and the terminal block. Insulate and seal the connection point. Connect the other end of the power cable to the corresponding interface on the control cabinet, following the circuit markings. Ensure the positive and negative terminals, and the phase and neutral wires, are correctly connected. After correct connection, tighten the terminals inside the control cabinet, close and lock the cabinet door. Simultaneously connect the data cable to the torsional vibration viscosity sensor, temperature sensor, electric valve, and ground signal receiving equipment to ensure smooth data transmission.

[0089] Then, connect the main power supply to the electrical control cabinet, turn on the power switch, set the heating and insulation parameters, and start the heating function. The heating insulation layer enters normal working state. The electrical control cabinet automatically receives real-time temperature data transmitted by the temperature sensor and viscosity data transmitted by the torsional vibration viscosity sensor, and controls the start and stop of the electric heating wire in combination with the preset parameters. When the temperature of the target object reaches the set insulation temperature, the electric heating wire stops heating or switches to low-temperature insulation mode. When the temperature is lower than the insulation threshold, the electric heating wire automatically starts to supplement heat and maintain temperature stability. This ensures the dewaxing effect while achieving energy saving.

[0090] When heating and insulation are no longer needed, first turn off the heating function of the heating and insulation layer through the electrical control cabinet, keep the power supply connected, and wait for the temperature of the target object to drop naturally to a safe temperature before turning off the main power supply of the electrical control cabinet and disconnecting the power supply of the ground power supply system. During this process, the temperature sensor continuously collects temperature data and transmits it to the ground to provide a basis for judging whether a safe temperature has been reached.

[0091] In summary, the present invention has the following beneficial effects:

[0092] This invention abandons the empirical proportional formulas used in traditional viscosity monitoring. Instead, it constructs a dedicated calculation formula adapted to the flow tube of a torsional vibration viscosity sensor through dynamic derivation. It embeds downhole flow velocity and coating wear compensation terms into the fluid viscosity calculation formula, eliminating the need for empirical coefficient correction and significantly improving viscosity monitoring accuracy. The formula parameters are based on actual structural measurements, automatic equipment acquisition, and initial downhole calibration values. It can be embedded into a sensor module to achieve real-time automatic viscosity calculation, making operation convenient. Furthermore, the formula relies on existing sensor structural designs, requiring only software embedding of the calculation formula for upgrades, resulting in low modification costs. Simultaneously, accurate monitoring can be linked to the dewaxing module for on-demand automatic adjustment, improving the intelligence and energy efficiency of downhole dewaxing.

[0093] By controlling heating parameters and electric valve status in a closed loop based on real-time viscosity data, incomplete dewaxing or energy waste caused by rough heating is eliminated, while secondary problems such as crude oil cracking and formation damage are avoided, thus extending the service life of the equipment.

[0094] The short connector adopts a threaded connection design, which can be flexibly installed in any well section without changing the original oil production process; the matching insulation and straightening components ensure operational safety, and the disassembly and maintenance are convenient, adapting to different well types and working conditions.

[0095] This invention integrates monitoring, heating, and control into one unit, forming an automated closed-loop operation that requires no manual intervention, reduces the frequency of well shutdowns, improves the continuous production efficiency of oil wells, and at the same time strengthens the insulation and sealing design to reduce the risk of downhole failures.

[0096] In addition, the electric valve, torsional vibration viscosity sensor, and temperature sensor in this invention are functionally equivalent replacements. Any similar device that can achieve the corresponding function of this technical solution falls within the scope of this protection. Among them, the temperature sensor and torsional vibration viscosity sensor only need to meet the requirements of downhole high temperature and high pressure conditions and be able to realize real-time temperature acquisition and data transmission. There is no need to limit the specific model, which improves the versatility of the solution.

[0097] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are 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 scope of protection of the claims of the present invention.

Claims

1. A downhole intelligent dewaxing device based on online fluid viscosity monitoring, characterized in that: The downhole intelligent dewaxing device includes a tubular short connector, which is equipped with a torsional vibration viscosity sensor and a temperature sensor for collecting the viscosity of the fluid inside the tubing and the temperature around the tubing. Both the torsional vibration viscosity sensor and the temperature sensor are connected to the data processing center. The oil pipe has a split structure, including an upper oil pipe and a lower oil pipe. The upper oil pipe and the lower oil pipe are respectively connected to the upper and lower openings of the short connection. The lower oil pipe and the middle and lower part of the short connection are wrapped with a heating and insulation layer. The data processing center and the heating and insulation layer are both connected to the ground power supply system. The tubing is installed inside the casing, and an insulating centralizer is installed in the annulus between the tubing and the casing. The casing is installed inside the wellbore, and a sucker rod is installed inside the tubing. A sucker rod pump is installed at the lower end of the sucker rod. The heating and insulation layer is embedded with an electric heating wire, and the terminals of the electric heating wire are electrically connected to the electrical control cabinet via a power supply cable. The electrical control cabinet is electrically connected to the ground power supply system. The data processing center controls the heating or heat preservation of the electric heating wire based on the temperature data collected by the temperature sensor, and controls the start and stop of the electric heating wire based on the fluid viscosity collected by the torsional vibration viscosity sensor, thereby achieving dewaxing regulation. A bypass channel is provided inside the side wall of the short connector, which extends upwards and outwards to the top surface of the short connector. An upper horizontal channel, communicating with a monitoring hole on the upper oil pipe, is provided on the upper side of the bypass channel. A lower horizontal channel, facing the gap between the upper and lower oil pipes, is provided on the lower side of the bypass channel. The torsional vibration viscosity sensor is located in the upper part of the bypass channel, with its probe corresponding to the upper horizontal channel. An electric valve is located in the middle of the bypass channel. The temperature sensor is located on the side of the bypass channel and at the top of the short connector. The lower part of the torsional vibration viscosity sensor is fitted with the orifice of the bypass channel through a base. The lower end of the base is connected to the pendulum through a torsion tube. Two sets of piezoelectric ceramic elements are placed inside the pendulum. One set is a driving piezoelectric ceramic for driving the pendulum, and the other set is a feedback piezoelectric ceramic, which can measure and control the rotation of the pendulum through feedback signals. A flow tube is provided outside the torsion tube and the pendulum. The torsional vibration viscosity sensor, temperature sensor, and electric valve are all connected to the ground signal receiving equipment via data cables, and the ground signal receiving equipment is connected to the data processing center.

2. The intelligent downhole dewaxing device based on online fluid viscosity monitoring according to claim 1, characterized in that: The data processing center, electrical control cabinet, and ground power supply system are all located on the ground, and the ground power supply system provides power to the data processing center, electrical control cabinet, and heating and insulation layer.

3. The intelligent downhole dewaxing device based on online fluid viscosity monitoring according to claim 1, characterized in that: The torsional vibration viscosity sensor employs the working principle of torsional vibration-phase difference detection, driving a piezoelectric ceramic to drive a pendulum at its natural frequency. Resonant vibration occurs when downhole fluid flows through the sucker rod, generating viscous damping on the pendulum; the feedback piezoelectric ceramic captures two sets of resonant frequencies corresponding to a ±45° phase difference. , Calculate the resonant frequency difference Combining downhole operating condition interference compensation, fluid viscosity is calculated through formula derivation. The calculation formula is as follows: ； In the formula: : Downhole fluid dynamic viscosity, Pa·s; The resonant frequency corresponding to a +45° phase difference, in Hz; The resonant frequency corresponding to a -45° phase difference, in Hz; The resonant frequency difference corresponding to a phase difference of ±45° , Hz; Torsional vibration viscosity sensor: pendulum moment of inertia, kg·m²; : Inner radius of the cylindrical flow tube of the torsional vibration viscosity sensor, in meters; L: Effective length of the cylindrical flow tube, in meters; The uniform gap between the flow tube and the pendulum, in meters (m). : Fluid velocity inside the oil pipe, m / s; Wear amount of coating on flow tube surface, μm; : The natural frequency of the pendulum, Hz; Flow velocity compensation coefficient, calibrated through downhole multi-condition experiments, dimensionless; Coating wear compensation coefficient, calibrated through downhole multi-condition experiments, dimensionless; The real-time fluid viscosity value obtained by the above formula The data is transmitted in real time to the ground signal receiving equipment via data cable and synchronized to the data processing center. The data processing center completes the reception, analysis, storage and status monitoring of the downhole data, and synchronizes the real-time viscosity value to the electrical control cabinet. Critical viscosity threshold of wax plugging inside electrical control cabinet After receiving the fluid viscosity value, it automatically compares and judges it with the threshold, and realizes power supply control for the downhole heating and insulation layer through the power supply cable: when the real-time fluid viscosity value... Reaching or exceeding the critical viscosity threshold for wax blockage At that time, the electrical control cabinet outputs a power supply signal to the heating and insulation layer through the power supply cable to heat and reduce the viscosity of the downhole fluid and dissolve the wax; when the real-time viscosity value Reduced to the critical viscosity threshold of wax blockage When the following occurs, the electrical control cabinet immediately cuts off the power output of the power supply cable, the heating insulation layer stops heating, and the dewaxing control is completed.

4. The intelligent downhole dewaxing device based on online fluid viscosity monitoring according to claim 1, characterized in that: An insulated sucker rod is provided on the upper exterior of the sucker rod to ensure insulation between the tubing and the sucker rod.

5. The intelligent downhole dewaxing device based on online fluid viscosity monitoring according to claim 1, characterized in that: The lower oil pipe and the middle and lower part of the short connection are filled with thermal insulation material between them and the corresponding heating and insulation layer.

6. A downhole intelligent dewaxing method based on online fluid viscosity monitoring, characterized in that: Includes the following steps: First, assemble the downhole intelligent dewaxing device as described in any one of claims 1-5, and simultaneously install the torsional vibration viscosity sensor and temperature sensor on the shorting, and then place the tubing and the shorting with the heating and insulation layer into the target monitoring position in the wellbore in sequence. Then, connect the main power supply of the electrical control cabinet, turn on the power switch, set the heating and insulation parameters, start the heating function, and the heating insulation layer enters normal working state; the electrical control cabinet automatically receives real-time temperature data transmitted by the temperature sensor and viscosity data transmitted by the torsional vibration viscosity sensor, and controls the start and stop of the electric heating wire in combination with the preset parameters. When the temperature of the target object reaches the set insulation temperature, the electric heating wire stops heating or switches to low-temperature insulation mode; when the temperature is lower than the insulation threshold, the electric heating wire automatically starts to supplement heat to maintain temperature stability; When heating and insulation are no longer needed, first turn off the heating function of the heating and insulation layer through the electrical control cabinet, keep the power supply connected, and wait for the temperature of the target object to drop naturally to a safe temperature before turning off the main power supply of the electrical control cabinet and disconnecting the power supply of the ground power supply system. During this process, the temperature sensor continuously collects temperature data and transmits it to the ground to provide a basis for judging whether a safe temperature has been reached.

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