High-power high-temperature cable heating process for underground petroleum

Abstract

The invention discloses an underground petroleum high-power high-temperature cable heating process, and aims to solve the problems of poor cable insulation performance, short heating duration, low oil extraction production efficiency, low energy consumption and the like in the prior art. Comprising the following steps: feeding a raw material into a non-welding sheath tube formed by a vertical roller through a stainless steel band unwinding device and a conductor unwinding device of automatic equipment; magnesium oxide powder is poured into a gap between the stainless steel sheath and the conductor core wire, and the magnesium oxide powder is compacted until the density is greater than or equal to 2.8 g / cm < 3 >. And then rolling is carried out through a multi-pass vertical rolling mill and a multi-pass horizontal rolling mill, finally, the qualified heating cable is produced, and then annealing and nitrogen protection process treatment are carried out on line so as to improve the flexibility and smoothness of the cable. According to the invention, the automation level of underground heating cable production is greatly improved, the insulation compactness of the cable and the strength of a welding sheath are ensured, the production efficiency and the product quality are improved, and the device is suitable for underground oil layer heating industrial application occasions with higher requirements.

Description

Technical Field

[0001] The invention relates to the technical field of cable processing, in particular to a downhole petroleum high-power high-temperature heating cable process. Background Art

[0002] Mineral insulated cables (BTTZ cables) have been widely used in the fields of petrochemicals, nuclear energy, and electric power due to their excellent properties such as fire resistance, high temperature resistance, and radiation resistance. The insulation layer of this type of cable is filled with magnesium oxide powder, covered with a metal sheath on the outside, and copper or other conductive core wires on the inside. There are several technical difficulties in the production process of traditional mineral insulated cables: such as uneven density of magnesium oxide powder filling, unstable sheath welding, and insufficient online detection methods in the process, which can easily lead to substandard cable performance. At the same time, the degree of automation of production line equipment is low, and the product qualification rate and production efficiency need to be improved.

[0003] In the prior art, the common mineral insulated cable production process mostly uses manual or semi-automatic equipment, and there are errors in the stainless steel tube forming, welding and filling process. In particular, welding deviations are easily generated due to the inability to accurately and automatically track the weld during welding. In addition, the magnesium oxide powder is not vibrated sufficiently during the filling process, resulting in a decrease in the insulation performance of the cable, thereby affecting the product quality and stability. Therefore, it is of great practical significance to develop a mineral insulated cable production process that can improve the filling density of magnesium oxide powder, improve welding accuracy and automated production efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a downhole oil high-power high-temperature heating cable process. The process injects high-power high-temperature integrated distributed electric heating pipe cables into the ground under pressure, and the heating pipe cables heat the water or steam injected into the ground in the formation to form high-temperature and high-pressure saturated steam. The saturated steam effectively heats the oil layer, reduces the viscosity of heavy oil and super-heavy oil, increases its fluidity, improves the recovery rate, or realizes recovery; through stepless power regulation of heating power and heating time, the temperature and pressure of the oil layer are accurately controlled to meet the needs of different formations and oil reservoirs; it reduces heat energy consumption and carbon emissions, and is more energy-saving and environmentally friendly.

[0005] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0006] The present invention comprises the following steps:

[0007] S1: Prepare stainless steel strips and conductor wires according to design requirements, adjust the strip unwinding device and wire unwinding device, and preheat the magnesium oxide powder for standby use;

[0008] S2: The stainless steel strip is formed into a preliminary tube shape by a forming machine, and the longitudinal seam of the stainless steel tube is welded;

[0009] S3: Preheated magnesium oxide powder is poured into the welded stainless steel pipe, and the magnesium oxide powder is introduced into the gap between the sheath and the core wire through the fixed core pipe, and then the stainless steel pipe filled with magnesium oxide powder is vibrated;

[0010] S4: Use a vertical rolling mill for multiple rolling passes to reduce the diameter of the stainless steel pipe and further compact the magnesium oxide powder. After vertical rolling, the copper stainless steel pipe needs to be annealed online and then further rolled by a horizontal rolling mill;

[0011] S5: Use eddy current testing equipment for non-destructive testing, and then measure the diameter and take up the finished product;

[0012] S6: The finished cable is tested for core eccentricity, magnesium oxide thickness, voltage, and sheath wall thickness. The qualified cables are sealed at the head and tail to complete the processing.

[0013] Preferably, in step S1, the copper strip has a thickness of 0.85 to 3.5 mm and a width of 60 to 150 mm; the copper wire needs to be straightened according to predetermined specifications, and the diameter of the copper wire core ranges from Φ3.1 to Φ10 mm; the magnesium oxide powder should be preheated; and the initial tap density of the magnesium oxide powder should not be less than 2.1 g / cm 3 The unwinding speed of the stainless steel strip is adjusted within the range of 0.1-4m / min according to production requirements; the unwinding speed can be adjusted to 0-10m / min.

[0014] In step S2, the copper strip is pressed into a preliminary tube shape using a flat roller and a vertical roller. The forming speed can be adjusted to 0.1-3 m / min. The diameter of the formed stainless steel tube is Φ20 mm to Φ50 mm. The welding speed can be adjusted to 0.1-3 m / min.

[0015] In step S3, the filling speed is synchronized with the production line speed, and the speed range is 0.1-3 m / min; the vibration frequency is adjusted to 20-80 times / min, and the vibration force is controlled at 5-20N; the compaction density of the magnesium oxide after final vibration needs to reach ≥2.8g / cm 3 .

[0016] In step S4, the maximum rolling force of the roller is 450 kN, and the rolling speed can be adjusted to 0.1-3 m / min; the annealing temperature is controlled at 800-900°C; the outer diameter of the finished product after rolling by the horizontal rolling mill is between Φ7.3 mm and Φ30 mm, and the outer diameter tolerance of the sheath is controlled between ±0.05 mm and ±0.1 mm.

[0017] The detection accuracy of the eddy current detection equipment in step S5 is an error of ≤0.02mm, and the measurement frequency is 200 times / second; the outer diameter measurement error range is ≤0.02mm; and the take-up speed adjustment range is 1.25-10m / min.

[0018] In the step S6, the eccentricity of the core wire is detected to be no more than 0.1 mm; the thickness of magnesium oxide is no less than 80%-0.1 mm of the nominal value, and the tolerance of the sheath wall thickness is controlled within ±10%.

[0019] The beneficial effects of the present invention are:

[0020] The present invention is a process for underground oil high-power high-temperature heating cables. Compared with the prior art, the present invention solves many problems existing in the traditional production process by introducing a fully automated production line and advanced detection devices. Specifically, the present invention uses high-precision automated stainless belt forming and welding equipment to achieve precise forming and welding of stainless steel sheath pipes, thereby improving welding quality; and uses advanced magnesium oxide filling and vibration devices to ensure that the filling density of magnesium oxide powder meets standard requirements, thereby enhancing the insulation performance of the cable.

[0021] In addition, through multiple vertical and horizontal rolling processes, the dimensional accuracy of the cable sheath, such as the outer diameter and wall thickness, is significantly improved, ensuring the roundness and consistency of the cable. During the entire production process, online eddy current detection, laser diameter measurement and length measurement equipment are used to monitor the various parameters of the cable in real time to ensure the quality stability of the finished product. Through the automated production process of the present invention, production efficiency is greatly improved, the product qualification rate reaches more than 95%, reducing production costs and manual intervention, while improving the controllability of product quality.

[0022] In summary, the present invention significantly improves the degree of automation of the mineral insulated cable production line, improves the electrical and mechanical properties of the cable, and meets the technical requirements of higher-end application environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention;

[0024] Figure 2 It is a schematic structural diagram of another embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0026] Example:

[0027] like Figure 1 As shown: The present invention comprises the following steps:

[0028] S1: Prepare stainless steel strips and conductor wires according to design requirements, adjust the strip unwinding device and wire unwinding device, and preheat the magnesium oxide powder for standby use;

[0029] S1.1 Raw material preparation:

[0030] Preparation of stainless steel strip and conductor wire: According to the design requirements, the surface of the stainless steel strip is cleaned to ensure that there is no oil stain or metal impurities. The thickness of the stainless steel strip is 0.85-3.5mm and the width is 60-150mm. The conductor wire needs to be straightened according to the predetermined specifications, and the conductor wire core diameter ranges from Φ3.1 to Φ10mm.

[0031] Preparation of magnesium oxide powder: The magnesium oxide powder should be preheated to ensure its dry state and stored in a magnesium oxide storage tank. The initial tap density of the magnesium oxide powder should not be less than 2.1g / cm 3 .

[0032] S1.2 Unloading:

[0033] Stainless steel belt unwinding: Using FD400 unwinding device, the unwinding speed of stainless steel belt is adjusted in the range of 0.1-4m / min according to production requirements, with tension control function to avoid unwinding. The tension range of unwinding device is 0.4-0.6MPa.

[0034] Conductor pay-off: The conductor wire is passively paid out through the F800 / F2000 pay-off device. The pay-off speed can be adjusted to 0-10m / min to ensure that the conductor wire is not affected by excessive tension.

[0035] S2: The stainless steel strip is formed into a preliminary tube shape by a forming machine, and the longitudinal seam of the stainless steel tube is welded;

[0036] S2.1 Strip forming: The stainless steel strip enters the CX203240 forming machine through the guide wheel, and the flat roller and vertical roller are used to press the stainless steel strip into a preliminary tube shape. The forming speed can be adjusted to 0.1-3m / min. The diameter of the formed stainless steel tube is Φ20mm to Φ50mm.

[0037] S2.2 Argon arc welding: Use H800A argon arc welding system to weld the longitudinal seam of stainless steel pipe, and the welding speed can be adjusted to 0.1-3m / min. A double welding gun system is used during welding to ensure the continuity of welding, and the single welding length can reach 2000 meters. During welding, the weld alignment accuracy must be maintained, and the deviation must be controlled within ±0.01mm.

[0038] The welding current is 500A (100% duty cycle) during welding, and the arc is started at high frequency to ensure smooth welding. The welding temperature is monitored and automatically adjusted through a real-time feedback system.

[0039] S3: Preheated magnesium oxide powder is poured into the welded stainless steel pipe, and the magnesium oxide powder is introduced into the gap between the sheath and the core wire through the fixed core pipe, and then the stainless steel pipe filled with magnesium oxide powder is vibrated;

[0040] S3.1 Magnesium oxide powder filling: In the welded stainless steel pipe, the preheated magnesium oxide powder is filled into the stainless steel pipe through the G-1000T magnesium oxide filling device. The magnesium oxide is introduced into the gap between the sheath and the core wire through the fixed core tube. The filling speed is synchronized with the production line speed, and the speed range is 0.1~3m / min.

[0041] S3.2 Vibration compaction: Use a vibrating hammer to compact the stainless steel tube filled with magnesium oxide powder. The vibration frequency can be adjusted to 20-80 times / minute, and the vibration force is controlled at 5-20N. The final compaction density of magnesium oxide after vibration must reach **≥2.8g / cm 3 **, ensuring the stability of the internal insulation layer.

[0042] S4: Use a vertical rolling mill for multiple rolling passes to reduce the diameter of the stainless steel pipe and further compact the magnesium oxide powder. After vertical rolling, the stainless steel pipe needs to be annealed online and then further rolled by a horizontal rolling mill;

[0043] S4.1 Vertical rolling: Use CZ-8-220 vertical rolling mill for multiple passes to reduce the diameter of the stainless steel pipe and further compact the magnesium oxide powder. During rolling, the maximum rolling force of the roller is 450kN, and the rolling speed can be adjusted to 0.1-3m / min.

[0044] S4.2 Online annealing: After vertical rolling, the stainless steel pipe needs to be annealed online. The stainless steel pipe is heated by 1# heat treatment equipment and the annealing temperature is controlled at 800-900℃ to soften and restore its plasticity.

[0045] S4.3 Horizontal rolling: After annealing, the stainless steel pipe enters the 1# horizontal rolling mill (SPZJ-6-220) and the 2# horizontal rolling mill (SPZJ-12-220) for further rolling. The outer diameter of the finished product is between Φ7.3mm and Φ50mm, and the outer diameter tolerance of the sheath is controlled between **±0.05mm and ±0.1mm** to ensure that the design size requirements are met.

[0046] S5: Use eddy current testing equipment for non-destructive testing, and then measure the diameter and take up the finished product;

[0047] S5.1 Nondestructive testing: Use eddy current testing equipment to perform nondestructive testing to ensure that there are no cracks, pores or other defects inside the cable. The detection accuracy of the testing equipment is ≤0.02mm, and the measurement frequency is 200 times / second.

[0048] S5.2 Finished product measurement and marking: Use C-XY-50 diameter measuring device to measure the outer diameter of the finished product, with an error range of **≤0.02mm** (invention patent for heating cable technology description). At the same time, laser marking is performed using JM-0005 length measuring and marking device, with a laser power of **≥30W**, and the marking content includes production date, serial number, etc.

[0049] S5.3 Finished product take-up: The finished product is automatically taken up by the S-2000 gantry take-up device, and the take-up speed automatically matches the production line, with an adjustment range of 1.25 to 10 m / min. The reel load is **≥15 tons** to ensure the stability of the take-up.

[0050] S6: The finished cable is tested for core eccentricity, magnesium oxide thickness, and sheath wall thickness. The qualified cables are sealed at the head and tail to complete the processing.

[0051] S6.1 Finished product inspection: Each batch of finished cables must be inspected according to GB / T13033.1-2007 standards. The eccentricity of the core wire shall not exceed 0.1mm, the thickness of magnesium oxide shall not be less than 80%-0.1mm of the nominal value, and the sheath wall thickness tolerance shall be controlled within ±10%.

[0052] S6.2 Finished product packaging: After the qualified cables are marked, the heads and tails are sealed and packaged. The length of each reel of finished cable ranges from 1200 to 3000 meters to facilitate transportation and installation.

[0053] The cable manufactured by the process of this embodiment has the following technical features:

[0054] 1: Mineral insulated heating cables can achieve unlimited length requirements and wireless heating depth requirements. They can be spliced ​​through a splicing machine to meet the requirements of long-length production, which is more advantageous than limited-length heating cables on the market;

[0055] 2: The maximum temperature resistance of mineral insulated heating cable can reach 800 degrees. According to the different characteristics of underground oil, the actual required temperature is 30-90 degrees.

[0056] 3: The withstand voltage of mineral insulated heating cable can reach 7500V, and the actual working voltage is 3500V;

[0057] 3: The stainless steel outer sheath of the mineral insulated cable can withstand a pressure of 150MPA.

[0058] As another embodiment, the heating cable Figure 2As shown in the figure, 1 is a stainless steel sheath, 2 is a thermocouple, 3 is a core wire, and 4 is magnesium oxide powder; the process is the same as the above embodiment, wherein the thermocouple is a commonly used temperature measuring element, and its basic function is to convert the temperature signal into a thermoelectric potential signal, and then convert it into the temperature of the measured medium through an electrical instrument. Thermocouples are widely used in various industrial fields, such as measuring the temperature of gas or liquid in furnaces and pipelines, and the surface temperature of solids. The structure of the thermocouple usually consists of two metal conductors of different components to form a closed loop. When there is a temperature difference between the two ends, a thermoelectric potential is generated in the loop, thereby measuring the temperature. This working principle enables the thermocouple to accurately reflect the temperature change of the measured medium. In addition, the thermocouple also has its unique application form in specific applications, such as the magnet thermocouple, which can closely attach the sensor to the surface of the object through a strong adsorption force to achieve high-precision temperature measurement. In the gas stove, the thermocouple also plays the role of flameout protection. When the flame is extinguished, the thermocouple can trigger the solenoid valve to close the gas valve to ensure safety.

[0059] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A downhole petroleum high-power high-temperature heating cable process, characterized in that: The following steps are involved: S1: Prepare stainless steel strips and conductor wires according to design requirements, adjust the strip unwinding device and wire unwinding device, and preheat the magnesium oxide powder for standby use; S2: The stainless steel strip is formed into a preliminary tube shape by a forming machine, and the longitudinal seam of the stainless steel tube is welded; S3: Preheated magnesium oxide powder is poured into the welded stainless steel pipe, and the magnesium oxide powder is introduced into the gap between the sheath and the core wire through the fixed core pipe, and then the stainless steel pipe filled with magnesium oxide powder is vibrated; S4: Use a vertical rolling mill for multiple rolling passes to reduce the diameter of the stainless steel pipe and further compact the magnesium oxide powder. After vertical rolling, the stainless steel pipe needs to be annealed online and then further rolled by a horizontal rolling mill; S5: Use eddy current testing equipment for non-destructive testing, and then measure the diameter and take up the finished product; S6: The finished heating cable is subjected to core wire eccentricity detection, magnesium oxide insulation detection, sheath wall thickness detection, and pressure testing. The qualified cables are sealed at the head and tail to complete the processing.

2. The downhole petroleum high-power high-temperature heating cable process according to claim 1 is characterized in that: In step S1, the thickness of the stainless steel strip is 0.85-3.5 mm and the width is 60-150 mm; the conductor wire needs to be straightened according to the predetermined specifications, and the conductor wire core diameter ranges from Φ3.1 to Φ10 mm; the magnesium oxide powder is preheated; the initial tap density of the magnesium oxide powder should be not less than 2.1 g / cm 3 The unwinding speed of the stainless steel strip is adjusted within the range of 0.1-4m / min according to production requirements; the unwinding speed can be adjusted to 0-10m / min.

3. The downhole petroleum high-power high-temperature heating cable process according to claim 2 is characterized in that: In step S2, the copper strip is pressed into a preliminary tube shape using a flat roller and a vertical roller. The forming speed can be adjusted to 0.1-3 m / min. The diameter of the formed stainless steel tube is Φ20 mm to Φ50 mm. The welding speed can be adjusted to 0.1-3 m / min.

4. The downhole petroleum high-power high-temperature heating cable process according to claim 3 is characterized by: In step S3, the filling speed is synchronized with the production line speed, and the speed range is 0.1-3 m / min; the vibration frequency is adjusted to 20-80 times / min, and the vibration force is controlled at 5-20N; the compaction density of the magnesium oxide after final vibration needs to reach ≥2.8g / cm 3 .

5. The downhole petroleum high-power high-temperature heating cable process according to claim 4 is characterized in that: In step S4, the maximum rolling force of the roller is 450 kN, and the rolling speed can be adjusted to 0.1-3 m / min; the annealing temperature is controlled at 800-900°C; the outer diameter of the finished product after rolling by the horizontal rolling mill is between Φ7.3 mm and Φ50 mm, and the outer diameter tolerance of the sheath is controlled between ±0.05 mm and ±0.1 mm.

6. The downhole petroleum high-power high-temperature heating cable process according to claim 5 is characterized by: The detection accuracy of the eddy current detection equipment in step S5 is an error of ≤0.02mm, and the measurement frequency is 200 times / second; the outer diameter measurement error range is ≤0.02mm; and the take-up speed adjustment range is 1.25-10m / min.

7. The downhole petroleum high-power high-temperature heating cable process according to claim 6 is characterized by: In the step S6, the eccentricity of the core wire is detected to be no more than 0.1 mm; the thickness of magnesium oxide is no less than 80%-0.1 mm of the nominal value, and the tolerance of the sheath wall thickness is controlled within ±10%.

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