Segmented heating system for oil well

Abstract

The utility model discloses an oil well segmented heating system, relates to the technical field of oil well thermal recovery, and mainly aims to perform segmented selective heating on an underground oil pipe of an oil well. According to the main technical scheme, the oil well segmented heating system comprises a cable outer armor arranged in an oil pipe, a first cable core, a second cable core and a temperature measuring optical fiber are arranged in the cable outer armor in parallel, the lower end of the first cable core is connected to a first connecting position on the inner side face of the cable outer armor, and the lower end of the second cable core is connected to a second connecting position on the inner side face of the temperature measuring optical fiber. The lower end of the second cable core is connected to a second connecting position on the inner side face of the cable outer armor, the second connecting position is lower than the first connecting position, the upper end of the first cable core is connected to the power supply unit through a first switch, the upper end of the cable outer armor is connected to the power supply unit through a third switch, and the upper end of the temperature measuring optical fiber is electrically connected to the input end of the controller. The output end of the controller is electrically connected to the first switch, the second switch and the third switch.

Description

TECHNICAL FIELD

[0001] The utility model relates to oil well thermal recovery technical field especially relates to an oil well subsection heating system. BACKGROUND

[0002] In the heavy oil thermal recovery process of oil field, through injecting hot fluid or steam to oil layer, the underground heavy oil is heated, the viscosity of heavy oil is reduced, the flowability of crude oil is improved, and the heavy oil is more easily exploited. For the oil well with high wax content, hot washing wax removal is generally used on the oil field, the temperature of wellbore fluid is improved through the circulation flushing of hot fluid in the wellbore, so that the wax deposited in the oil pipe is melted, thereby the purpose of wax removal is achieved.

[0003] The most important thing in these processes is hot liquid or steam; they are heated on the ground, and there are problems such as large loss and low efficiency in the process of transportation to the underground. Moreover, the heavy oil thermal recovery needs to heat the oil layer at the bottom of the oil well, and the wax deposition of the oil well is mainly in the upper part of the oil well. The hot washing wax removal mainly heats the wax deposition part in the upper part of the oil well, but the heavy oil thermal recovery and the hot washing wax removal method of the oil field heat the whole wellbore, which cannot achieve precise heating, resulting in heat loss. SUMMARY

[0004] Therefore, the utility model embodiment provides an oil well subsection heating system, and the main purpose is to selectively heat the underground oil pipe of the oil well in sections.

[0005] In order to achieve the above purpose, the utility model mainly provides the following technical scheme:

[0006] The utility model embodiment provides an oil well subsection heating system, and the main purpose is to selectively heat the underground oil pipe of the oil well in sections.

[0007] The heating cable includes a cable outer armor, a first cable core, a second cable core and a temperature measuring optical fiber, the cable outer armor is arranged in the oil pipe, the first cable core, the second cable core and the temperature measuring optical fiber are arranged in parallel in the cable outer armor, the lower end of the first cable core is connected to the first connecting position of the inner side of the cable outer armor, the lower end of the second cable core is connected to the second connecting position of the inner side of the cable outer armor, the second connecting position is lower than the first connecting position, the upper end of the first cable core is connected to the power supply unit through the first switch, the upper end of the second cable core is connected to the power supply unit through the second switch, the upper end of the cable outer armor is connected to the power supply unit through the third switch, the upper end of the temperature measuring optical fiber is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the first switch, the second switch and the third switch respectively.

[0008] The purpose of the utility model and the technical problems thereof can also be further realized by the following technical measures.

[0009] Optionally, a first high-temperature-resistant sealing filler is further included, and the first high-temperature-resistant sealing filler is filled in the outer armor of the cable.

[0010] Optionally, a base, a conical cable clamp, a cable sealing cover and a sealing gland are further included, the base is installed on the upper end of the Christmas tree of the oil pipe, the cable sealing cover wraps the conical cable clamp, the lower end surface of the cable sealing cover is bolted to the base, the sealing gland is tightly pressed on the upper end of the cable sealing cover, the cable sealing cover is filled with a second high-temperature-resistant sealing filler, and the upper end of the outer armor of the cable sequentially penetrates through the base, the conical cable clamp, the cable sealing cover and the sealing gland.

[0011] Optionally, a DTS temperature acquisition unit is further included, the upper end of the temperature measuring optical fiber is connected to the input end of the DTS temperature acquisition unit, and the output end of the DTS temperature acquisition unit is connected to the input end of the controller.

[0012] Optionally, the power supply unit includes an alternating current power supply, a rectifier, an inverter and an isolation transformer which are sequentially connected, the first switch includes a first branch switch and a second branch switch, one end of the first branch switch and one end of the second branch switch are respectively connected to the upper end of the first cable core, the other end of the first branch switch is connected to one end of the secondary winding of the isolation transformer, the other end of the second branch switch is connected to the other end of the secondary winding of the isolation transformer, one end of the second switch is connected to the upper end of the second cable core, and the other end of the second switch is connected to one end of the secondary winding of the isolation transformer, one end of the third switch is connected to the upper end of the outer armor of the cable, and the other end of the third switch is connected to the other end of the secondary winding of the isolation transformer.

[0013] Optionally, the first cable core and the second cable core are of the same structure and each include a red copper conductor and a polyimide film and a mica tape which are sequentially wrapped outside the red copper conductor.

[0014] Optionally, the temperature measuring optical fiber includes a temperature measuring core, a temperature-resistant inner sheath, a stainless steel spiral, a tensile fiber bundle, a stainless steel woven net and a temperature-resistant outer sheath which are sequentially wrapped outside the temperature measuring core.

[0015] By means of the above technical scheme, the utility model at least has the following advantages:

[0016] When the upper oil pipe needs to be heated, the controller sends a closing instruction to the first switch and the third switch, the current loop in which the first cable core and the outer armor of the cable are located is turned on, and heat is generated on the path of the current loop through the outer armor of the cable by the skin effect, so that the upper oil pipe is heated.

[0017] When the whole section of the oil pipe needs to be heated, the controller sends a closing instruction to the second switch and the third switch, the current loop in which the second cable core and the cable outer armor are located is conducted, and heat is generated by the skin effect on the path of the current loop through the cable outer armor, so that the whole section of the oil pipe is heated;

[0018] When the lower section of the oil pipe needs to be heated, the controller sends a closing instruction to the first switch and the second switch, the current loop in which the first cable core, the cable outer armor and the second cable core are located is conducted, and heat is generated by the skin effect on the cable outer armor between the first connection position and the second connection position, so that the lower section of the oil pipe is heated;

[0019] The temperature values of different positions of the oil pipe are measured by the temperature measuring optical fiber, the controller adjusts the specific heating mode (upper section heating, lower section heating or whole section heating) according to the temperature value electrical signal, and adjusts the heating power according to the difference between the set temperature and the measured temperature, so that closed-loop temperature regulation control is realized;

[0020] The skin effect heating has high efficiency, reduces energy waste, has good energy-saving effect, and reduces carbon emissions.

[0021] Since the heating component is the outer armor, it belongs to the external heating mode, which is beneficial to timely heat transfer to the surrounding medium, heat accumulation is not easy to form in the heating cable, and therefore the service life of the heating cable is guaranteed, and the maintenance of the downhole part is reduced.

[0022] By using the system, the skin effect segmented heating method is adopted, the skin effect heating pipe is placed in the wellbore of the oil well, the liquid in the wellbore is heated, the skin effect heating pipe can heat the liquid in the wellbore in sections according to different heating positions of the oil well, energy loss in the heat source transmission process is reduced, invalid heating is reduced, heating efficiency is improved, and the energy efficiency ratio is improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A structure schematic view of the oil well segmented heating system is provided for the embodiment of the utility model;

[0024] Figure 2 An axial sectional view of the oil well segmented heating system is provided for the embodiment of the utility model;

[0025] Figure 3 An axial sectional view of the heating cable;

[0026] Figure 4 A circuit connection schematic view of the oil well segmented heating system is provided for the embodiment of the utility model;

[0027] Figure 5 A control principle diagram of the oil well segmented heating system is provided for the embodiment of the utility model.

[0028] The reference signs in the drawings of the specification include: tubing 1, heating cable 2, cable outer armor 201, first cable core 202, second cable core 203, temperature measuring optical fiber 204, first switch 3, first branch switch 301, second branch switch 302, second switch 4, third switch 5, base 6, conical cable clamp 7, cable sealing cover 8, sealing gland 9, Christmas tree 10, alternating current power supply 11, rectifier 12, inverter 13, isolation transformer 14, power supply unit 15. DETAILED DESCRIPTION

[0029] To further clarify the technical means and effects taken by the present application to achieve the predetermined application purpose, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in combination with the drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0030] The present application will be further described in detail in combination with the drawings and embodiments.

[0031] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 An embodiment of the present application provides an oil well segmented heating system, which comprises: tubing 1 and heating cable 2.

[0032] The heating cable 2 comprises cable outer armor 201, first cable core 202, second cable core 203 and temperature measuring optical fiber 204, the cable outer armor 201 is arranged in the tubing 1, the first cable core 202, the second cable core 203 and the temperature measuring optical fiber 204 are arranged in parallel in the cable outer armor 201, the lower end of the first cable core 202 is connected to the first connection position of the inner side of the cable outer armor 201, the lower end of the second cable core 203 is connected to the second connection position of the inner side of the cable outer armor 201, the second connection position is lower than the first connection position, the upper end of the first cable core 202 is connected to the power supply unit 15 through the first switch 3, the upper end of the second cable core 203 is connected to the power supply unit 15 through the second switch 4, the upper end of the cable outer armor 201 is connected to the power supply unit 15 through the third switch 5, the upper end of the temperature measuring optical fiber 204 is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the first switch 3, the second switch 4 and the third switch 5 respectively.

[0033] The working process of the oil well segmented heating system is as follows:

[0034] When the upper section of the oil pipe 1 needs to be heated, the controller sends a closing instruction to the first switch 3 and the third switch 5, the current loop in which the first cable core 202 and the cable outer armor 201 are located is turned on, and heat is generated on the path of the current loop passing through the cable outer armor 201 by the skin effect, thereby achieving heating of the upper section of the oil pipe 1.

[0035] When the entire section of the oil pipe 1 needs to be heated, the controller sends a closing instruction to the second switch 4 and the third switch 5, the current loop in which the second cable core 203 and the cable outer armor 201 are located is turned on, and heat is generated on the path of the current loop passing through the cable outer armor 201 by the skin effect, thereby achieving heating of the entire section of the oil pipe 1.

[0036] When the lower section of the oil pipe 1 needs to be heated, the controller sends a closing instruction to the first switch 3 and the second switch 4, the current loop in which the first cable core 202, the cable outer armor 201, and the second cable core 203 are located is turned on, and heat is generated on the cable outer armor 201 between the first connection position and the second connection position by the skin effect, thereby achieving heating of the lower section of the oil pipe 1.

[0037] The temperature values at different positions of the oil pipe 1 are measured by the temperature measurement optical fiber 204, and the controller adjusts the specific heating mode of the oil pipe 1 (upper section heating, lower section heating, or entire section heating) according to the temperature value electrical signal, thereby forming a closed-loop control.

[0038] The skin effect heating has high efficiency, reduces energy waste, has good energy-saving effect, and reduces carbon emissions.

[0039] Since the heating component is the outer armor, it belongs to an external heating method, which is conducive to the timely transfer of heat to the surrounding medium, and heat accumulation is not easy to form inside the heating cable 2, thereby ensuring the service life of the heating cable 2 and reducing the maintenance of the downhole part.

[0040] Specifically, the first connection position is located in the middle of the cable outer armor 201, and the second connection position is located at the lower end of the cable outer armor 201; the cable outer armor 201 is made of low-carbon steel with excellent magnetic permeability.

[0041] In the specific embodiment, a first high-temperature-resistant sealing filler is also included, which is filled in the cable outer armor 201.

[0042] In the embodiment, specifically, the first high-temperature-resistant sealing filler is filled between the first cable core 202 and the second cable core 203 in the cable outer armor 201, thereby stabilizing the relative position between the first cable core 202 and the second cable core 203 and avoiding direct contact between the first cable core 202 and the second cable core 203.

[0043] Specifically, glass fiber is used as the covering material between the cable core and the inner surface of the cable outer armor 201 to avoid short circuit of the circuit at positions other than the first and second connection positions.

[0044] As shown in Figure 1 and Figure 2 In the specific embodiment, the base 6 is installed on the upper end of the Christmas tree 10 of the oil pipe 1, the cable sealing cover 8 wraps the conical cable clamp 7, the lower end surface of the cable sealing cover 8 is bolted to the base 6, the sealing gland 9 is tightly pressed on the upper end of the cable sealing cover 8, the cable sealing cover 8 is filled with a second high-temperature-resistant sealing filler, and the upper end of the cable outer armor 201 penetrates the base 6, the conical cable clamp 7, the cable sealing cover 8 and the sealing gland 9 in sequence.

[0045] In the embodiment, specifically, the base 6 is installed on the upper end of the Christmas tree 10 of the oil pipe 1 by flange connection to ensure wellhead sealing.

[0046] Specifically, the upper end of the heating cable 2 penetrates the sealing gland 9, and the cable outer armor 201 is reliably grounded.

[0047] As shown in Figure 5 In the specific embodiment, the DTS temperature acquisition unit is further included, the upper end of the temperature measuring optical fiber 204 is connected to the input end of the DTS temperature acquisition unit, and the output end of the DTS temperature acquisition unit is connected to the input end of the controller.

[0048] In the embodiment, specifically, the temperature measuring optical fiber 204 is connected to the DTS temperature acquisition unit to acquire the temperature of the oil pipe 1 at each segment of the oil well, the controller controls the heating frequency, power, time, selection of the heating segment, temperature of the heating segment and the like according to the set parameters, and feeds back the real-time data of the acquired downhole temperature and wellhead temperature to the back end for analysis.

[0049] As shown in Figure 4 and Figure 5As shown, in the specific embodiment, the power supply unit 15 comprises the alternating current power supply 11, the rectifier 12, the inverter 13 and the isolation transformer 14 connected in sequence, the first switch 3 comprises the first branch switch 301 and the second branch switch 302, one end of the first branch switch 301 and one end of the second branch switch 302 are connected to the upper end of the first cable core 202, the other end of the first branch switch 301 is connected to one end of the secondary winding of the isolation transformer 14, the other end of the second branch switch 302 is connected to the other end of the secondary winding of the isolation transformer 14, one end of the second switch 4 is connected to the upper end of the second cable core 203, and the other end is connected to one end of the secondary winding of the isolation transformer 14, one end of the third switch 5 is connected to the upper end of the cable outer armor 201, and the other end is connected to the other end of the secondary winding of the isolation transformer 14.

[0050] In the present embodiment, the rectifier 12 rectifies the alternating current into direct current, the inverter 13 modulates the direct current into a single pulse power supply of a certain frequency, and distributes it to each switch terminal through the isolation transformer 14, and by closing or opening different switches, the selection of the heating section of the oil pipe 1 is realized.

[0051] Specifically, when the upper section of the oil pipe 1 needs to be heated, the first branch switch 301 and the third switch 5 are closed, and the cable outer armor 201, the first cable core 202 and the secondary winding of the isolation transformer 14 form a closed loop.

[0052] When the entire oil pipe 1 needs to be heated, the second switch 4 and the third switch 5 are closed, and the cable outer armor 201, the second cable core 203 and the secondary winding of the isolation transformer 14 form a closed loop.

[0053] When the lower section of the oil pipe 1 needs to be cooled, the second branch switch 302 and the second switch 4 are closed, and the first cable core 202, the cable outer armor 201, the second cable core 203 and the secondary winding of the isolation transformer 14 form a closed loop.

[0054] In the specific embodiment, the first cable core 202 and the second cable core 203 have the same structure, and each comprises a red copper conductor, a polyimide film and a mica tape wrapped around the red copper conductor in sequence from inside to outside.

[0055] In the present embodiment, specifically, the core advantage of the present cable core structure lies in its "trinity" high-performance combination: (1) red copper conductor: provides excellent conductive basis; (2) polyimide film (inner layer): provides high heat resistance, high insulation, chemical resistance, radiation resistance, flexibility and mechanical protection of the inner layer barrier; (3) mica tape (outer layer): provides super high heat resistance, non-combustible, fire resistance, arc resistance, corona resistance, radiation resistance, high insulation of the outer layer barrier, and enhances the mechanical strength under high temperature.

[0056] This design is especially suitable for extreme high temperature, high reliability / long life, fire risk (fire resistance, low smoke halogen-free), chemical corrosion or radiation, etc. It is an ideal choice for high-end special cables (such as aerospace cables, nuclear power cables, ship cables, high-temperature furnace cables, fire-resistant cables, etc.).

[0057] Specifically, the first cable core 202 and the second cable core 203 are spirally twisted and twisted together, which facilitates the synchronous insertion of the first cable core 202 and the second cable core 203 into the cable outer armor 201 when the heating cable 2 is produced.

[0058] In a specific embodiment, the temperature measuring optical fiber 204 includes a temperature measuring fiber core, a temperature-resistant inner sheath, a stainless steel spiral, a tensile fiber bundle, a stainless steel woven mesh, and a temperature-resistant outer sheath, which are sequentially wrapped around the temperature measuring fiber core from the inside to the outside.

[0059] In this embodiment, specifically, the temperature measuring optical fiber 204 has excellent temperature resistance, extremely high mechanical strength and tensile performance, excellent anti-flattening and impact resistance, good bending resistance, good chemical protection and corrosion resistance, reliable signal transmission stability, and extended service life, enabling long-term, stable, and reliable high-precision temperature monitoring in the oil well pipe 1.

[0060] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any skilled person in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An oil well segmented heating system characterized by, It comprises: a tubing; a heating cable, the heating cable comprises a cable outer armor, a first cable core, a second cable core and a temperature measuring optical fiber, the cable outer armor is arranged in the tubing, the first cable core, the second cable core and the temperature measuring optical fiber are arranged in parallel in the cable outer armor, the lower end of the first cable core is connected to the first connection position of the inner side of the cable outer armor, the lower end of the second cable core is connected to the second connection position of the inner side of the cable outer armor, the second connection position is lower than the first connection position, the upper end of the first cable core is connected to the power supply unit through the first switch, the upper end of the second cable core is connected to the power supply unit through the second switch, the upper end of the cable outer armor is connected to the power supply unit through the third switch, the upper end of the temperature measuring optical fiber is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the first switch, the second switch and the third switch respectively.

2. The oil well segmented heating system according to claim 1, wherein it further comprises a first high-temperature-resistant sealing filler, and the first high-temperature-resistant sealing filler is filled in the cable outer armor.

3. The oil well segmented heating system according to claim 1, wherein it further comprises a base, a conical cable clamp, a cable sealing cover and a sealing gland, the base is installed on the upper end of a Christmas tree of the tubing, the cable sealing cover wraps the conical cable clamp, the lower end surface of the cable sealing cover is bolted to the base, the sealing gland is pressed on the upper end of the cable sealing cover, the cable sealing cover is filled with a second high-temperature-resistant sealing filler, and the upper end of the cable outer armor penetrates the base, the conical cable clamp, the cable sealing cover and the sealing gland in sequence.

4. The oil well segmented heating system according to claim 1, wherein it further comprises a DTS temperature acquisition unit, the upper end of the temperature measuring optical fiber is connected to the input end of the DTS temperature acquisition unit, and the output end of the DTS temperature acquisition unit is connected to the input end of the controller.

5. The oil well segmented heating system according to claim 1, wherein the power supply unit comprises an alternating current power supply, a rectifier, an inverter and an isolation transformer connected in sequence, the first switch comprises a first branch switch and a second branch switch, one end of the first branch switch and one end of the second branch switch are connected to the upper end of the first cable core respectively, the other end of the first branch switch is connected to one end of a secondary winding of the isolation transformer, the other end of the second branch switch is connected to the other end of the secondary winding of the isolation transformer, one end of the second switch is connected to the upper end of the second cable core, and the other end is connected to one end of the secondary winding of the isolation transformer, one end of the third switch is connected to the upper end of the cable outer armor, and the other end is connected to the other end of the secondary winding of the isolation transformer.

6. The oil well segmented heating system according to any one of claims 1 to 5, wherein The first cable core and the second cable core are of the same structure, and each comprises a red copper conductor, a polyimide film and a mica tape wrapped around the red copper conductor in sequence from inside to outside.

7. The segmented oil well heating system of any one of claims 1 to 5, wherein, The temperature measuring optical fiber comprises a temperature measuring fiber core, a temperature-resistant inner sheath wrapped around the temperature measuring fiber core in sequence from inside to outside, a stainless steel spiral, a tensile fiber bundle, a stainless steel woven net and a temperature-resistant outer sheath.

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