Insulating oil pipe well fluid heating system

Abstract

The utility model relates to the field of oil exploitation, in particular to an insulating tubing well fluid heating system which mainly solves the problems that an existing electric heating device of a rod-pumped well is low in heat efficiency and large in energy loss and affects the space of a shaft. The oil pipe comprises an oil pipe body and a cable, an insulating layer is arranged on the outer surface, except oil pipe threads, of an outer insulating oil pipe body (2), an insulating layer is arranged on the inner surface of an inner insulating oil pipe body (6), and the outer insulating oil pipe body (2) and the inner insulating oil pipe body (6) are connected through an insulating short circuit (5); one end of the in-well cable (10) is connected with the control cabinet (9), and the other end is connected with the cable short circuit (4); one end of the grounding cable (11) is connected with the control cabinet (9), and the other end is connected to a wellhead flange; and the contactor (1) is connected between the outer insulating oil pipe (2) and the sleeve (15). The insulating oil pipe well fluid heating system is high in heat efficiency, good in heating efficiency and more energy-saving, does not occupy the space of a shaft, and does not affect subsequent well repair operation.

Description

Technical Field

[0001] This utility model relates to the field of oil extraction, specifically to an insulated oil pipe well fluid heating system. Background Technology

[0002] When pumping wells are in operation, low temperatures in northern regions cause waxes and gums in the crude oil to precipitate, increasing the crude oil's viscosity and reducing its fluidity. This further increases the load on the sucker rod, raises motor power consumption, and may even lead to a decrease in well production due to poor fluidity. The risk of wax deposition is also exacerbated, clogging tubing or screens and reducing fluid production. Simultaneously, if the temperature is too low (especially in water-bearing wells), hydrates or ice blockage may form, completely blocking the flow path and increasing the risk of wellbore freezing. This necessitates steam injection or chemical unblocking, thereby increasing unplanned operating costs.

[0003] Currently, the commonly used heating and insulation measures for pumping wells typically involve wrapping the wellhead and surface pipelines with insulation material to reduce heat loss. However, this insulation method cannot be used on downhole tubing. For downhole tubing, some are equipped with electric heating devices, most of which are heating cables installed on the outside of the tubing. However, these heating devices have low thermal efficiency, high energy loss, and restrict the wellbore space, affecting subsequent well workover operations. Utility Model Content

[0004] To overcome the shortcomings of existing electric heating devices for oil pumping wells, such as low thermal efficiency, high energy loss, and impact on wellbore space, this utility model provides an insulated tubing well fluid heating system. This insulated tubing well fluid heating system has high thermal efficiency, good heating efficiency, and is more energy-saving. Furthermore, it does not occupy wellbore space and will not affect subsequent well workover operations.

[0005] The technical solution of this utility model is: an insulating oil pipe well fluid heating system, including an oil pipe and a cable. The cable includes a well cable and a grounding cable. The oil pipe includes several outer insulating oil pipes and inner insulating oil pipes. The outer insulating oil pipes are provided with an insulating layer on their outer surface except for the oil pipe threads. The inner insulating oil pipes are provided with an insulating layer on their inner surface. The inner insulating oil pipes are located above all the outer insulating oil pipes. The outer insulating oil pipes and the inner insulating oil pipes are connected by an insulating short circuit. The inner surface of the insulating short circuit is provided with an insulating layer.

[0006] One end of the well cable is connected to the control cabinet, and the other end is connected to a cable short circuit after entering the well. The cable short circuit is connected between two external insulated oil pipes; one end of the grounding cable is connected to the control cabinet, and the other end is connected to the wellhead flange.

[0007] The outer insulating oil pipe is provided with a sleeve, and the bottom outer insulating oil pipe and the sleeve are connected by a contactor.

[0008] Furthermore, two adjacent external insulating oil pipes are connected by an oil pipe coupling, and the outer surface of the oil pipe coupling, except for the oil pipe thread, is provided with an insulating layer.

[0009] Furthermore, protective sleeves are fixed to both ends of the outer insulating layer of the external insulating oil pipe.

[0010] Furthermore, the insulating layer of the oil pipe coupling is externally fixed with a coupling protective sleeve.

[0011] Furthermore, insulating gaskets are provided inside both ends of the insulating short circuit.

[0012] Furthermore, the oil pipe is equipped with an insulated sucker rod inside, and the outer surface of the insulated sucker rod is provided with an insulating layer.

[0013] Furthermore, the upper end of the insulated sucker rod is connected to an insulated smooth rod, and the outer surface of the insulated smooth rod is provided with an insulating layer.

[0014] Furthermore, the control cabinet outputs DC power below 36 volts.

[0015] This invention offers the following advantages: By adopting the above-mentioned solution, an insulating layer is installed outside the tubing and tubing coupling. The lower ends of the tubing and casing are connected via a contactor and a cable. When the control cabinet power is activated, DC power flows through the cable sequentially through the tubing, tubing coupling, contactor, and casing back to the control cabinet, thus forming a circuit. During this process, the DC power generates heating power, heating the well fluid and raising its temperature. This invention significantly saves energy because it only requires a DC power output of less than 36V; it directly acts on the well fluid during heating, resulting in high thermal efficiency; and since only one cable is needed to enter the well, it does not occupy wellbore space and will not affect subsequent well workover operations. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the downhole portion of this utility model.

[0018] In the diagram, 1-Contaminator, 2-Outer insulating oil pipe, 3-Oil pipe coupling, 4-Cable short circuit, 5-Insulation short circuit, 6-Inner insulating oil pipe, 7-Insulated sucker rod, 8-Casing gate valve, 9-Control cabinet, 10-Well entry cable, 11-Grounding cable, 12-Insulated smooth rod, 13-Coupling protective sleeve, 14-Oil pipe protective sleeve, 15-Casing. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described. 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 protection scope of the present invention.

[0020] In the description of this utility model, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "top", and "bottom" are all based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of this utility model and simplify the description, and is not intended to indicate or imply that the indicated component 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 utility model.

[0021] Depend on Figure 1 , Figure 2 As shown, an insulating oil tubing well fluid heating system includes an oil tubing and a cable. The oil tubing comprises several outer insulating oil tubing 2 and inner insulating oil tubing 6. The outer insulating oil tubing 2 has an insulating layer on its outer surface except for the tubing threads. Adjacent outer insulating oil tubing 2 are connected by an oil tubing coupling 3. Similarly, the outer surface of the oil tubing coupling 3 is also covered with an insulating layer. The tubing threads of both the outer insulating oil tubing 2 and the oil tubing coupling 3 are not coated with an insulating layer, thus ensuring that the connected outer insulating oil tubing 2 forms a conductive insulating oil tubing. The outer surface of the insulating oil tubing is covered with an insulating coating.

[0022] Oil pipe protective sleeves 14 are fixed to both ends of the outer insulating layer of the outer insulating oil pipe 2. The oil pipe protective sleeves 14 are located near the oil pipe threads of the outer insulating oil pipe 2 and can protect the insulating layer of the outer insulating oil pipe 2 from damage when tightening the oil pipe with hydraulic pliers. Similarly, a coupling protective sleeve 13 is fixed to the outside of the insulating layer of the oil pipe coupling 3, which can also protect the insulating layer on the surface of the oil pipe coupling 3 from damage when tightening the oil pipe with hydraulic pliers. The oil pipe protective sleeves 14 need to be firmly fixed to the internal oil pipe to ensure that the oil pipe protective sleeves 14 and the outer insulating oil pipe 2 do not rotate relative to each other when tightening the oil pipe; similarly, the coupling protective sleeves 13 also need to be firmly fixed to the internal coupling to ensure that the coupling protective sleeves 13 and the oil pipe coupling 3 do not rotate relative to each other when tightening the oil pipe.

[0023] The inner insulating tubing 6 has an insulating layer on its inner surface to prevent electrical conduction between the tubing body and the well fluid. The length of the inner insulating tubing 6 is determined according to the water content of the oil well, typically between 6 and 60 meters. Its lower end is connected to the uppermost outer insulating tubing 2 via an insulating short connector 5, and its upper end is connected to the wellhead flange. The inner surface of the insulating short connector 5 has an insulating layer, and it connects the inner and outer insulating tubing. An insulating gasket is also provided inside the insulating short connector 5, ensuring an insulating break in the middle of the short connector. This serves both as a tubing short connector and as an electrical barrier between the upper and lower tubing, preventing electrical conduction between the outer insulating tubing 2 and the inner insulating tubing 6.

[0024] The cables include a wellbore entry cable 10 and a grounding cable 11. The wellbore entry cable 10 has an insulating coating and a steel armor protective layer, capable of carrying currents above 800A. One end of the wellbore entry cable 10 is connected to the control cabinet 9, and the other end enters the well through the casing gate 8, with the end connected to a cable short connector 4. The cable short connector 4 connects between two externally insulated tubing sections 2. To reduce cable length and save wellbore space, the cable short connector 4 is typically connected between the first and second externally insulated tubing sections 2. The end of the wellbore entry cable 10 is fixed to the cable short connector 4, and power can be supplied to the tubing through the control cabinet 9. One end of the grounding cable 11 is connected to the control cabinet 9, and the other end is connected to the wellhead flange.

[0025] This utility model also includes a contactor 1, which is connected between the bottom outer insulating oil pipe 2 and the sleeve 15, and plays a conductive role, which can transmit the current flowing through the oil pipe to the sleeve through contact with the sleeve.

[0026] An insulated sucker rod 7 is installed inside the tubing, and an insulating layer is provided on the outer surface of the insulated sucker rod 7. An insulated polished rod 12 is connected to the upper end of the insulated sucker rod 7, and an insulating layer is provided on the outer surface of the insulated polished rod 12. The purpose of the insulated sucker rod 7 and the insulated polished rod 12 is to electrically isolate the sucker rod body or polished rod body from the external well fluid.

[0027] The insulating layer in this invention can be made of polymer resin material, or it can be coated with insulating materials such as silicon carbide, aluminum oxide, or other new plastic materials.

[0028] The control cabinet 9, the wellbore cable 10, the cable shorting 4, the tubing, the contactor 1, the bushing 15, and the grounding cable 11 of this utility model form a single circuit. The control cabinet 9 outputs DC power below 36V. When the power supply to the control cabinet 9 is turned on, the DC current flows sequentially through the wellbore cable 10, the cable shorting 4, the outer insulating tubing 2, the tubing coupling 3, through the contactor 1, through the bushing 15, and then back to the control cabinet via the grounding cable 11, thus forming a circuit. When the main circuit current flows through the bushing and tubing, the DC power generates heating power, thereby raising the temperature of the well fluid and reducing the risk of waxing, scaling, and freezing due to high fluid viscosity at low winter temperatures.

[0029] During this process, the insulation short circuit 5 isolates the current between the outer insulating oil pipe 2 and the inner insulating oil pipe 6, while the inner insulating oil pipe 6, the insulating sucker rod 7 and the insulating polished rod 12 isolate the well fluid from electricity, so that only a very small portion of the current is diverted, which will not affect the main circuit.

[0030] The present invention will be further described below with reference to embodiments:

[0031] In this embodiment, contactor 1 is a 100mm-126mm-800A contactor with a main body outer diameter of 100mm, a spring-loaded contact head outer diameter of 126mm, and an inner diameter of 62mm, consistent with the specifications of ordinary oil pipes. The outer insulating oil pipe 2 has an outer diameter of 78mm, and the oil pipe coupling 3 has an outer diameter of 95mm. In this embodiment, the external insulation layer of the outer insulating oil pipe 2 and the oil pipe coupling 3 is coated with HDPE.

[0032] In this embodiment, the main circuit current flows primarily through the casing and tubing, with a designed length of 500 meters. Based on the resistivity formula, the theoretical resistance of this circuit is 0.057 ohms. If outputting a maximum 36V DC voltage, it can generate 630A of current, resulting in a heating power of 22.5kW. Through controllable adjustment of the DC voltage from 12-36V, the power can be adjusted from 2.5kW to 22.5kW. If the voltage adjustment range is increased to the industrial safety voltage of 72V, it can generate 1250A of current, resulting in a heating power of 90kW, sufficient to heat the well fluid, replace water mixing, and achieve direct single-well pumping.

[0033] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An insulated tubing well fluid heating system comprising a tubing, a cable, the cable comprising a downhole cable (10) and a grounding cable (11), characterized in that: The oil pipe comprises several outer insulated oil pipes (2) and inner insulated oil pipes (6), the outer surface of the outer insulated oil pipes (2) is provided with an insulation layer except the pipe thread, the inner surface of the inner insulated oil pipes (6) is provided with an insulation layer, the inner insulated oil pipes (6) are located above the outer insulated oil pipes (2), and the outer insulated oil pipes (2) and the inner insulated oil pipes (6) are connected through insulation short circuits (5), the inner surface of the insulation short circuits (5) is provided with an insulation layer; One end of the downhole cable (10) is connected with the control cabinet (9), the other end of the downhole cable (10) is connected with the cable short circuit (4) after entering the well, the cable short circuit (4) is connected between two outer insulated oil pipes (2); one end of the grounding cable (11) is connected with the control cabinet (9), the other end of the grounding cable (11) is connected with the wellhead flange; The outer surface of the outer insulated oil pipe (2) is provided with a sleeve (15), the outer insulated oil pipe (2) at the bottom and the sleeve (15) are connected through a contactor (1).

2. The insulated tubing well fluid heating system of claim 1, wherein: Two adjacent outer insulated oil pipes (2) are connected through an oil pipe coupling (3), the outer surface of the oil pipe coupling (3) is provided with an insulation layer except the pipe thread.

3. The insulated tubing well fluid heating system of claim 2, wherein: The outer ends of the insulation layers of the outer insulated oil pipes (2) are respectively fixed with pipe protection sleeves (14).

4. The insulated tubing well fluid heating system of claim 2, wherein: The outer surface of the oil pipe coupling (3) is fixed with a coupling protection sleeve (13).

5. The insulated tubing well fluid heating system of claim 1, wherein: The inner ends of the insulation short circuits (5) are respectively provided with insulation pads.

6. The insulated tubing well fluid heating system of claim 1, wherein: The oil pipe is internally provided with an insulated sucker rod (7), the outer surface of the insulated sucker rod (7) is provided with an insulation layer.

7. The insulated tubing well fluid heating system of claim 6, wherein: The upper end of the insulated sucker rod (7) is connected with an insulated polished rod (12), the outer surface of the insulated polished rod (12) is provided with an insulation layer.

8. The insulated tubing well fluid heating system of claim 1, wherein: The control cabinet (9) outputs direct current below 36 volts.

Images