Heating power supply integrated load-bearing submersible cable and heating control device thereof

Abstract

The present application relates to the technical fields of oilfield downhole working equipment, and particularly relates to a heating and power supply integrated load-bearing electric submersible cable and a heating control device thereof. The heating and power supply integrated load-bearing electric submersible cable and the heating control device thereof comprise a tubular armor layer, a filler is arranged between a power cable and a heating cable in the armor layer and is fixed by a wrapping layer, the power cable is connected with a ground power supply and a downhole device to transmit power, the heating cable is externally provided with a shielding layer and is in a bent shape in the armor layer, and two ends are connected with a direct current power supply output end to form a loop. The heating and power supply integrated load-bearing electric submersible cable and the heating control device thereof have the advantages that the armor layer is arranged to prevent the cable from shaking and support the cable, avoid damage to the insulation of the cable, and prolong the service life of the device; the heating cable and the power cable are integrated into the armor layer, and the power cable and the heating cable are lowered into the well together, thereby reducing working procedures and working costs.

Description

Technical Field

[0001] This invention relates to the field of oilfield downhole working equipment technology, and in particular to a load-bearing submersible cable with integrated heating and power supply and its heating control device. Background Technology

[0002] In oilfield downhole operations, downhole equipment needs to be connected to the surface power supply via cables. However, due to the lack of rod string disturbance within the tubing and the slow flow rate of crude oil in small- and medium-displacement wells, wax in the crude oil easily precipitates and condenses on the tubing wall, forming wax blockages and causing well shutdowns and economic losses. Current technology typically involves running an additional heating cable alongside the existing power cable for downhole equipment. This is costly and cumbersome, and the heating cable is easily damaged by the downhole environment, leading to decreased insulation and a shorter lifespan. To address these issues, existing technologies have improved the structure of the heating cable. However, these improved cables typically use three-phase power, resulting in poor heating efficiency. Furthermore, they still need to be separated from the power supply cable. Moreover, existing heating cables are usually suspended at the wellhead by a fixing device, and their own weight exerts a significant load when the cable sways downhole, further shortening its lifespan. Therefore, to address these shortcomings, a load-bearing submersible cable integrating heating and power supply, along with its heating control device, is proposed. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an integrated heating and power supply submersible cable and its heating control device, which solves the problems of high construction costs and cumbersome procedures associated with the need to install an additional heating cable to heat the downhole environment during downhole operations. It also addresses the issue of cables being easily damaged during downhole operations, leading to decreased cable insulation and shortened service life.

[0004] (II) Technical Solution To solve the above problems, the present invention provides an integrated heating and power supply submersible oil cable, comprising: The tubular armor layer is made of a hard material with good thermal conductivity. A power cable and a heating cable are installed within the armor layer. The top end of the power cable is connected to a surface power supply, and the bottom end is connected to the working equipment downhole for power transmission. The heating cable has a shielding layer on its surface to eliminate disturbances to the power cable caused by the current flow within the heating cable. The heating cable is bent within the armor layer and lowered into the well along with the armor layer. Both ends of the heating cable are connected to a DC power supply above ground, and the DC current flows within the heating cable, causing it to heat up downhole.

[0005] Preferably, each of the power cable and the heating cable contains a conductor.

[0006] Preferably, in the power cable and heating cable, an inner insulation layer is provided outside the conductor, and an outer insulation layer is provided outside the inner insulation layer, with the shielding layer of the heating cable covering the outer insulation layer.

[0007] Preferably, the inner and outer insulating layers are made of materials with good heat resistance and insulation.

[0008] Preferably, the inner insulation layer is formed by wrapping a polyimide composite film around the conductor surface and then sintering it, and the outer insulation layer is made of fluoroplastic.

[0009] Preferably, the inner wall of the armor layer is provided with a wrapping layer, and the wrapping layer contains filler material between the power cable, the heating cable and the wrapping layer.

[0010] The present invention also provides a downhole heating and power supply device, using the above-mentioned integrated heating and power supply load-bearing submersible cable, comprising: The equipment includes surface equipment and downhole equipment. The surface equipment includes a motor control cabinet and a heating control device, while the downhole equipment includes a submersible motor. The submersible motor is connected to the surface equipment via a cable body. Inside the cable body, the top end of the power cable is connected to the output end of the motor control cabinet, and the bottom end of the power cable is connected to the input end of the submersible motor. The connection points at both ends of the heating cable are connected to the output end of the heating control device, which inputs DC power into the heating cable for downhole heating and controls the heating efficiency.

[0011] Preferably, the input terminal of the heating control device is connected to an AC power source to convert AC power into DC power and input it into the heating cable.

[0012] Preferably, the heating control device includes a rectifier and a frequency converter. The output terminal of the rectifier is connected to the input terminal of the frequency converter, and the input terminal of the rectifier is connected to an AC power supply to rectify and convert the AC power into DC power, which is then input into the frequency converter.

[0013] Preferably, the input terminal of the frequency converter is equipped with a transformer, the input terminal of the transformer is connected to the output terminal of the frequency converter, the input terminal of the transformer is connected to the heating cable, and the transformer controls the voltage of the heating cable according to the ratio of the number of coils at the input and output terminals.

[0014] (III) Beneficial Effects The integrated heating and power supply submersible cable and its heating control device provided by this invention, by providing a rigid armor layer on the outermost layer of the cable, can fix the position of the cable during downhole operation, preventing the cable from shaking and providing full support for the cable, avoiding damage to its own insulation under its own weight, and extending the service life of the device; by integrating the heating cable and the power cable into the armor layer, the power cable and the heating cable can be lowered into the well together, simplifying the work process and reducing downhole working costs; by inputting DC power into the heating cable as the heating power source, the working efficiency of the device during downhole heating operation is improved. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the downhole heating power supply device of the present invention; Figure 2 This is a cross-sectional structural diagram of the integrated heating and power supply submersible cable of the present invention.

[0016] Among them, 1. power cable; 2. filler; 3. outer insulation layer; 4. conductor; 5. inner insulation layer; 6. armor layer; 7. wrapping layer; 8. shielding layer; 9. heating cable; 10. submersible motor; 11. motor control cabinet; 12. heating control device; 13. frequency converter; 14. rectifier; 15. transformer. Detailed Implementation

[0017] 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.

[0018] 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. Example 1:

[0019] like Figure 1As shown, this embodiment provides an integrated heating and power supply submersible cable, specifically including: a tubular armor layer 6, which is made of a hard material with good thermal conductivity. The armor layer 6 serves as the outer shell of the integrated heating and power supply submersible cable provided by this invention, used to support and enclose other internal components of the cable and fix them into a whole. After the required components are filled into the armor layer 6, the armor layer 6 is lowered into the well. Relying on its own strength, the armor layer 6 will fix the cable, preventing it from swaying during downhole operation. Simultaneously, the armor layer 6, in conjunction with the wellhead fixing and suspension devices, will support the cable's own weight, preventing the cable's insulation from decreasing during downhole operation due to its own weight acting entirely on the structure used to improve cable insulation. This maintains the cable's insulation during operation and extends the service life of the device. The armor layer 6 contains a power cable 1 and a heating cable 9. The top end of the power cable 1 is connected to the surface power supply, and the bottom end is connected to the working equipment underground for power transmission. The heating cable 9 is bent inside the armor layer 6 and lowered into the well along with the armor layer. Both ends of the heating cable 9 are connected to the DC power supply above ground. The DC current flows inside the heating cable 9, causing it to heat up underground. Typically, when the power cable 1 connects the surface power supply and the working equipment underground, the surface power supply is usually three-phase. Therefore, three power cables 1 are usually installed inside the armor layer 6, each connected to a voltage source of the three-phase power supply, which in turn connects to the input terminal of the working equipment underground. In special cases, such as when powering multiple working devices underground, the number of power cables 1 inside the armor layer 6 can be adjusted according to operational needs. Using DC current as the heating power source in the heating cable 9 provides higher heating efficiency and greater safety in low-voltage operating environments compared to traditional AC heating, as DC power requires a lower voltage to maintain a stable current within the heating cable 9. By integrating the heating cable 9 and the power cable 1 within the armor layer 6 to form a single integrated heating and power supply load-bearing submersible cable, both the power cable 1 and the heating cable 9 can be installed downhole simultaneously in a single operation, eliminating the need for repeated installations. This simplifies the process, reduces construction costs, and lowers the workload for workers.

[0020] Since heating cables 9 need to be installed inside and heated to the downhole environment through the electrothermal effect of heating cables 9, the material of the armor layer 6 must be able to support the weight of the internal components while ensuring that the heat in the heating cables 9 can be transferred to the well normally. This requires the armor layer 6 to have good thermal conductivity. Typically, the armor layer 6 is made of metal. Considering the material properties and economy, the armor layer 6 in this embodiment is usually made of 1mm thick 316L steel pipe. In addition to the above-mentioned required properties, 316L steel also has good corrosion resistance, can work for a long time in downhole operations, has a long service life, and can be reused multiple times.

[0021] The heating cable 9 works by passing current through it, causing it to heat up. However, if the heating cable 9 is too close to the power cable 1 during heating, the current flowing inside the heating cable 9 can disturb and affect the power transmission within the power cable 1, leading to unstable power transmission and reduced efficiency. To address this issue, a shielding layer 8 is provided on the surface of the heating cable 9 to eliminate the disturbance of the current flow within the heating cable 9 to the power cable 1. The shielding layer 8 utilizes the principle of electromagnetic shielding, tightly wound around the surface of the heating cable 9 to form a shielding layer that seals the electrons inside the heating cable 9 within the shielding layer 8, eliminating the disturbance and effect of the current inside the heating cable 9 on the power transmission within the power cable 1. Typically, the shielding layer 8 is formed of aluminum-plastic tape, which is evenly and tightly wound around the surface of the heating cable 9 to form a continuous and sealed shielding layer. In practical work, since the heating cable 9 needs to be lowered into the well, the shielding layer 8 needs to cover the entire outer surface of the heating cable 9, so the amount used is relatively large. At this time, aluminum-plastic tape is the most suitable material for shielding layer 8 under the premise of considering economy. When economic consideration is not required under special working requirements, aluminum-plastic tape can be replaced with other materials with better conductivity and ductility to make shielding layer 8.

[0022] Each of the power cable 1 and heating cable 9 contains a conductor 4. Conductor 4, as the core of both the power cable 1 and heating cable 1, carries the electricity during operation and typically uses a common copper cable core. Inside both the power cable 1 and heating cable 9, conductor 4 is surrounded by an inner insulation layer 5, and outside the inner insulation layer 5 is an outer insulation layer 3. The shielding layer 8 of the heating cable 9 covers the outer insulation layer 3. The inner insulation layer 5 and outer insulation layer 3 work together to form a double layer of protection, preventing the current flowing through conductor 4 of the power cable 1 and heating cable 9 from being transmitted into the well, thus avoiding leakage accidents and improving the safety of the device. Since the heating cable 9 generates heat during operation, and both the power cable 1 and heating cable 9 are located within the armor layer 6, the inner insulation layer 5 and outer insulation layer 3 are required to be made of heat-resistant and insulating materials to ensure that the insulation of the power cable 1 and heating cable 9 is not damaged by temperature during operation. Normally, conductor 4 generates heat when energized, therefore the heat resistance of the inner insulation layer 5 is generally greater than that of the outer insulation layer 5. Typically, the inner insulation layer 5 is formed by wrapping a polyimide composite film around the surface of conductor 4 and then sintering it, with a maximum applicable temperature of 320℃. The outer insulation layer 3 is made of fluoroplastic, with a maximum applicable temperature of 205℃. When cost is not a concern, the outer insulation layer 3 can be made of the same material as the inner insulation layer 5.

[0023] It is important to note that within the armor layer 6, an inner wall is provided with a wrapping layer 7. Inside the wrapping layer 7, between the power cable 1, the heating cable 9, and the wrapping layer 7, there is a filler material 2. The wrapping layer 7 and the filler material 2 work together to fix the positions of the power cable 1 and the heating cable 9 into a structurally stable whole. After adding the filler material 2 between the power cable 1 and the heating cable 9, the wrapping layer 7 tightly wraps the power cable 1, heating cable 9, and filler material 2, allowing them to be directly inserted into the armor layer 6. During the underground operation of the armor layer 6, the filler material 2 acts as a buffer between the power cable 1 and the heating cable 9, preventing friction between them within the armor layer 6 and avoiding damage to the insulation of their surfaces. Similar to the inner insulation layer 5 and the outer insulation layer 3, the filler material 2 and the wrapping layer 7 need to have good heat resistance to prevent damage to the heating cable 9 during operation. In this embodiment, the filler material 2 and the wrapping layer 7 are made of the same glass fiber tape, with a maximum applicable temperature of 260℃. Example 2:

[0024] like Figure 2As shown, this embodiment uses the aforementioned integrated heating and power supply submersible cable to provide a downhole heating and power supply device, including: surface equipment and downhole equipment. The surface equipment is mainly used to control the downhole equipment and provide power to it. The surface equipment includes a motor control cabinet 11 and a heating control device 12. The downhole equipment and the surface equipment are connected via the integrated heating and power supply submersible cable. Within the integrated heating and power supply submersible cable, the top end of the power cable 1 is connected to the output end of the motor control cabinet 11, and the bottom end of the power cable 1 is connected to the input end of the downhole equipment; the connection points at both ends of the heating cable 9 are connected to the output end of the heating control device 12 to form a circuit. The heating control device 12 inputs DC power into the heating cable 9 for downhole heating and controls the heating efficiency.

[0025] The motor control cabinet 11 serves as the power source for the surface and controls the downhole equipment. It provides power to the downhole equipment and controls its output electrical power to control the connected equipment and change its operating status. In practice, depending on the working environment and conditions, the motor control cabinet 11 can be replaced with other power sources, such as a three-phase power distribution cabinet, a mobile power supply, or a generator. The heating control device 12 controls the heating efficiency of the heating cable 9. During operation, depending on the type and purpose of the construction, the heating cable 9 needs to change its heating efficiency according to the work requirements. The heating control device 12 changes the output current power to alter the heating efficiency of the heating cable 9, enabling it to adapt to various downhole working environments.

[0026] The downhole equipment includes a submersible motor 10. The lower end of the power cable 1 is connected to the output end of the submersible motor 10, and the input end of the heating control device 12 is connected to an AC power source, converting the AC power into DC power which is then input into the heating cable 9. After being connected to the power cable 1, the submersible motor 10 is driven by the power cable 1. In actual operation, depending on the work content and requirements, the downhole equipment is not limited to the submersible motor 10; it can also be replaced with various mainstream submersible lift equipment such as electric submersible centrifugal pumps, electric submersible screw pumps, and electric submersible plunger pumps. Simultaneously, the heating control device 12 can be directly connected to an AC power source to convert the AC power into DC power to supply power to the heating cable 9, improving the practicality of the device and enabling it to adapt to various working environments.

[0027] The heating control device 12 includes a rectifier 14 and a frequency converter 13. The output of the rectifier 14 is connected to the input of the frequency converter 13, and the input of the rectifier 14 is connected to an AC power source, converting the AC power into DC power for input into the frequency converter 13. The rectifier 14 converts the input AC power into DC power to provide power to the heating cable 9. Since the frequency of the converted DC power is unstable, the frequency converter 13 adjusts the frequency of the input DC power to stabilize it, ensuring stable operation of the heating cable 9. The frequency converter 13 can also change the frequency of the output DC power according to operational needs, thereby ensuring that the heating efficiency of the heating cable 9 meets the operational requirements.

[0028] It should be noted that the input terminal of the frequency converter 13 is equipped with a transformer 15, the input terminal of which is connected to the output terminal of the frequency converter 13. The input terminal of the transformer 15 is also connected to the heating cable 9. The transformer 15 controls the voltage of the heating cable 9 according to the ratio of the number of coils at the input and output terminals. After the current is processed by the rectifier 14 and the frequency converter 13, although it has become DC, the voltage is relatively high. The transformer 15 can convert the high-voltage DC into low-voltage DC before inputting it into the heating cable 9. Working together with the frequency converter 13, it adjusts the heating efficiency of the heating cable 9, enabling the device to withstand various working environments of the inner tube.

[0029] In addition, transformer 15 has a circuit protection function. When the operating voltage reaches the dangerous voltage, transformer 15 will melt and break. Normally, a protection circuit is installed in the operating circuit of transformer 15. The operating current and voltage in transformer 9 also act on the protection circuit. When the operating current and voltage in transformer 15 exceed the carrying capacity of the protection circuit, the protection circuit melts and breaks the circuit in transformer 15, thereby shutting down transformer 15 and preventing damage to transformer 15 and heating cable 9 from current and voltage overload.

[0030] The integrated heating and power supply submersible cable and its heating control device provided by this invention can simultaneously run power cables and heating cables into the well, simplifying the process and reducing costs. Furthermore, it can support the weight of the cables themselves, reducing damage to the downhole cables. The specific operation process of this device is as follows: Step 1: According to work requirements, wrap the power cable, heating cable, and filler material with the wrapping layer and then insert them into the armor layer. At this point, the positions of the power cable and heating cable are fixed and they form a whole within the armor layer.

[0031] Step 2: Connect both ends of the power cable to the downhole equipment and the motor control cabinet, respectively, and connect both ends of the heating cable to the heating control device to form a circuit. Lower the cable into the well along with the armored layer. At this point, the power cable and heating cable are lowered into the well simultaneously under the protection of the armored layer; it is not necessary to lower the heating cable separately.

[0032] Step 3: Start the motor control cabinet and heating control device to simultaneously transmit power and perform downhole heating. During this process, the power cable transmits electricity from the motor control cabinet to the downhole equipment, providing power. The heating control device inputs DC current into the heating cable, and the current flowing within the heating cable heats it up, transferring the heat to the well environment to achieve downhole heating.

[0033] Step 4: Adjust the output power of the motor control cabinet and heating control device according to the work requirements so that the working power of the downhole equipment and the heating effect of the heating cable meet the work requirements.

[0034] This invention fully considers and solves the impact of heating temperature and frequency conversion control on cable insulation and long-distance vector transmission signals of downhole motors and sensors. It is not only suitable for unblocking and dewaxing in conventional oil reservoirs, but also for heat tracing production in unconventional oil reservoirs such as heavy oil and shale oil. It can be used in conjunction with various mainstream submersible oil lifting equipment such as electric submersible centrifugal pumps, electric submersible screw pumps, and electric submersible plunger pumps.

[0035] 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 oil cable integrating heating and power supply, characterized in that, include: A tubular armor layer (6) is made of a hard material with good thermal conductivity. A power cable (1) and a heating cable (9) are provided inside the armor layer (6). The top end of the power cable (1) is connected to the power supply on the ground, and the bottom end is connected to the working equipment downhole for power transmission. A shielding layer (8) is provided on the surface of the heating cable (9) to eliminate the disturbance of the current flow in the heating cable (9) to the power cable (1). The heating cable (9) is bent inside the armor layer (6) and lowered into the well with the armor layer. The two ends of the heating cable (9) are connected to the DC power supply on the surface to form a circuit. The DC current flows in the heating cable (9) to make the heating cable (9) heat up downhole.

2. The integrated heating and power supply submersible cable according to claim 1, characterized in that, Each of the power cable (1) and the heating cable (9) is provided with a conductor (4).

3. The integrated heating and power supply submersible cable according to claim 2, characterized in that, The power cable (1) and the heating cable have an inner insulation layer (5) outside the conductor (4) and an outer insulation layer (3) outside the inner insulation layer (5). The shielding layer (8) of the heating cable (9) covers the outer insulation layer (3).

4. The integrated heating and power supply submersible cable according to claim 3, characterized in that, The inner insulation layer (5) and the outer insulation layer (3) are made of heat-resistant and insulating materials.

5. The integrated heating and power supply submersible cable according to claim 4, characterized in that, The inner insulation layer (5) is formed by wrapping a polyimide composite film around the surface of the conductor (4) and then sintering it, while the outer insulation layer (3) is made of fluoroplastic.

6. The integrated heating and power supply submersible cable according to claim 3, characterized in that, The armor layer (6) has a wrapping layer (7) on its inner wall, and a filler (2) is provided between the power cable (1), the heating cable (9) and the wrapping layer (7).

7. A downhole heating and power supply device, using the integrated heating and power supply submersible cable as described in any one of claims 1-6, characterized in that, include: The surface equipment and the downhole equipment include a motor control cabinet (11) and a heating control device (12); the downhole equipment and the surface equipment are connected by an integrated heating and power supply submersible cable; in the integrated heating and power supply submersible cable, the top end of the power cable (1) is connected to the output end of the motor control cabinet (11), and the bottom end of the power cable (1) is connected to the input end of the downhole equipment; the connection points at both ends of the heating cable (9) are connected to the output end of the heating control device (12) to form a circuit, and the heating control device (12) inputs DC power into the heating cable (9) for downhole heating and controls the heating efficiency.

8. The downhole heating power supply device according to claim 7, characterized in that, The downhole equipment includes a submersible motor (10), the lower section of a power cable (1) is connected to the output end of the submersible motor (10), and the input end of a heating control device (12) is connected to an AC power source to convert AC power into DC power and input it into the heating cable (9).

9. The downhole heating power supply device according to claim 8, characterized in that, The heating control device (12) is equipped with a rectifier (14) and a frequency converter (13). The output end of the rectifier (14) is connected to the input end of the frequency converter (13). The input end of the rectifier (14) is connected to the AC power supply and rectifies the AC power into DC power, which is then input into the frequency converter (13).

10. The downhole heating power supply device according to claim 9, characterized in that, The input end of the frequency converter (13) is provided with a transformer (15), the input end of the transformer (15) is connected to the output end of the frequency converter (13), the input end of the transformer (15) is connected to the heating cable (9), and the transformer (15) controls the voltage of the heating cable (9) according to the ratio of the number of coils at the input and output ends.

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