JPS6210702B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a conduit for an electrode device for electrically heating underground hydrocarbon resources, and more specifically, the present invention relates to a method for manufacturing a conduit for an electrode device for electrically heating underground hydrocarbon resources. This relates to a manufacturing method. In the present specification, hydrocarbon underground resources refer to bitumen contained in oil sands or tar sands, and are hereinafter referred to as oil unless otherwise specified. In recent years, with the rise in the price of oil resources, serious consideration is being given to extracting oil from oil sand layers buried underground in countries such as Canada and Venezuela. This oil sand layer normally exists several hundred meters underground as a layer approximately 50 meters thick, but due to the high viscosity of this oil, it cannot be extracted by pumping it up at room temperature. The method used was to inject heated steam into the oil sand layer to raise the temperature of the oil, lower its viscosity, and then pump it. However, this method is inefficient and expensive, so a more productive method is to bury a conduit (steel pipe or stainless steel pipe) with an electrode at its tip so that the electrode is located in the oil sand layer. Two such oil extraction conduits are installed approximately 30 to 200 meters apart, and a voltage of several hundred to several thousand volts is applied between the two electrodes to raise the temperature of the oil sand layer by Joule heat, which increases the viscosity of the oil. A method of extracting oil by lowering the amount of oil was proposed. Since the resistivity of the oil sand layer is several times higher than that of the upper stratum, it is necessary to cover the part of the conduit buried in the stratum with an electrical insulator to prevent current from flowing through the upper stratum. It won't happen. This is because if it is not covered with an electrical insulator, current will flow through the strata and will not flow between the electrodes buried in the oil sand layer. Accordingly, there is a rapidly increasing need to develop conduits coated with electrical insulators that can withstand use under these special conditions. The characteristics that this electrical insulator must have are (A) withstand voltage characteristics of several hundred to several thousand volts, not only at room temperature but also at temperatures that can reduce the viscosity of oil in the oil sand layer (approximately 300°C); friend
( ^B ) A temperature at which the water contained in the oil sand can reduce the viscosity of the oil sand layer (approximately 300°C).
(C) Mechanical strength that allows the electrode to be suspended; It is required to have sufficient mechanical impact strength to prevent damage from contact. Conventionally, attempts have been made to use polyethylene resin, nylon resin, epoxy resin, etc. as electrical insulators for the above purpose, but polyethylene resin is sensitive to heat and melts at temperatures below 100°C, while nylon resin is sensitive to hot water. Hydrolysis occurs at around 100℃. Furthermore, epoxy resins also undergo hydrolysis at around 150°C, resulting in decreased electrical insulation properties, making them impractical. This invention was made in view of the above circumstances, and aims to provide a method for manufacturing a conduit for an electrode device for electric heating of hydrocarbon underground resources, which satisfies all of the conditions (A) to (C) above. This is the purpose. In view of this purpose, the present inventors have conducted extensive research and found that the outer circumferential surface of a metal conduit preheated to 350 to 380°C has a melt viscosity of 1400 to 1,400 at 380°C.
The above-mentioned conduit is made by applying powdered polyetheretherketone resin with a particle size of 10 to 100 μm at 2000 poise by electrostatic coating and melting it at 350 to 380°C to form a resin coating on the conduit surface. It was discovered that the present invention possesses all of the characteristics (A) to (C), and the present invention was completed. This invention will be described in detail below. Examples of the polyetheretherketone resin used in the present invention include aromatic polyetheretherketones represented by the following chemical structural formula and developed by Imperial Chemical Industries Ltd. in the UK. : This polyetheretherketone resin is in powder form and has the advantage that it can be applied and coated by electrostatic coating. The particle size of this resin is 10-100
Powders with a diameter of μm, preferably 20 to 70 μm, are used. If the particle size is smaller than 10 μm, the powder will aggregate and it will not be possible to adhere the powder uniformly. In addition, if the particle size is larger than 100 μm, when the powder is applied and then heated and melted, it will not form a flat coating, and air bubbles will be trapped inside the insulator, resulting in an insulator with excellent hot water resistance and electrical properties. You can't get a body. The melt viscosity of this resin at 380℃ is 1400~
2000 poise is used. If the melt viscosity at 380℃ is greater than 2000 poise, it is necessary to increase the preheating temperature and heating melting temperature of the metallic conduit during powder coating, and to increase the heating melting time, which may cause the metallic conduit to be oxidized. , the polyetheretherketone resin deteriorates, and an insulator with excellent hot water resistance and electrical properties cannot be obtained. If the melt viscosity at 380°C is less than 1400 poise, when the powder is applied and then heated and melted, the resin will drip from the pipe surface and the film will not be flat and uniform, resulting in poor hot water resistance and It is not possible to obtain an insulator with excellent electrical properties. As the metal conduit, for example, a steel pipe or a stainless steel pipe, which has excellent corrosion resistance and good electrical conductivity, is suitable. Then the conduit is 350-380
Preheated to ℃. If the conduit is not preheated or the preheating temperature is lower than 350° C., the strength of the fusion between the polyetheretherketone resin coating and the conduit is low, and the insulating coating will peel off from the conduit after it is left in hot water. If the preheating temperature is higher than 380℃,
When the powder is deposited, the melt flow is large and the film is not flat and uniform, making it impossible to obtain an insulator with excellent hot water resistance and electrical properties. The polyetheretherketone resin powder to be applied by electrostatic powder coating is heated and melted at a temperature of 350 to 380°C. If the melting temperature is lower than 350℃,
The melt flow of the polyether ether ketone resin is insufficient, and a uniform coating is not formed, causing air bubbles to be drawn into the interior of the insulator, making it impossible to obtain an insulator with excellent hot water resistance and electrical properties. Melting temperature is 380
If the temperature is higher than .degree. C., the melt flow of the polyetheretherketone resin is large, and it drips from the conduit surface, resulting in an uneven coating, making it impossible to obtain an insulator with excellent hot water resistance and electrical properties. Next, embodiments of a conduit electrically insulated according to the present invention will be described with reference to the drawings. FIG. 1 is a partial vertical cross-sectional view of the tip of a conduit coated with electrical insulation. Ketone resin insulator 3
is coated. Generally, the length of the conduit 2 is required to be about 200 to about 600 m, but since the length of one ordinary steel pipe or stainless steel pipe is 5 to 50 m, when inserting the tip into the oil sand layer is inserted while joining the conduit. FIG. 2 is a partial longitudinal cross-sectional view of a joint portion of a conduit coated with electrical insulation. When joining the body 3b to the covered conduit 2b, taper threads 5 are cut at the ends of each of the conduits 2a and 2b, and the coupling is performed using the coupling ring 4. In that case, in order to prevent electrical leakage from the joint, the joint, that is, the surface of the coupling 4 and the end of the conduit are further coated with an insulator 3c of polyether ether ketone resin. Next, regarding the coating method and properties of the polyetheretherketone electrical insulator of the present invention,
The present invention will be described in more detail with reference to some Examples and Comparative Examples, but the present invention is not limited to these Examples. Example 1 Powder of an aromatic polyetheretherketone resin manufactured by Imperial Chemical Industries Ltd. in the UK having the above structural formula and having a melt viscosity of 1400 to 2000 poise at 380°C and prepared to a particle size of 20 to 70 μm was heated at 370°C. It was applied by electrostatic coating to a preheated metal conduit, heated and melted at 370℃ for 10 minutes,
A polyetheretherketone resin film with a thickness of 0.3 mm was formed on the outer peripheral surface of the conduit. The electrostatic coating and heating and melting operations were repeated three more times (four times in total) to obtain a desired conduit insulator. Adhesive strength of the obtained insulator at 25℃ (Kg/
cm ² ), withstand voltage value (kV/mm) and its insulator.
The adhesion strength and withstand voltage values measured at 25°C after being immersed in hot water at 300°C for 500 hours are shown in Table 1 as Example 1. Examples 2 to 8 The preheating temperature of the metal conduit and the heating and melting conditions of the polyether ether ketone resin were changed to those shown in each example in Table 1, and the other conditions were the same as in Example 1, but electrical insulation was applied to the outer peripheral surface of the conduit. The properties of the electrical insulators obtained are shown in Table 1 as Examples 2 to 8. Comparative Examples 1 to 4 The preheating temperature and heating and melting conditions for the metal conduit were different from those in the above examples, but otherwise an electric insulator was formed on the outer peripheral surface of the conduit in the same manner as in Example 1. The characteristics are shown in Table 1 as Comparative Examples 1 to 4. Comparative Examples 5 to 7 Table 2 shows the results obtained by forming an electrical insulator on the outer circumferential surface of a conduit in the same manner as in Example 1, except that polyetheretherketone resin powder having a particle size outside the range of the present invention was used. The properties of the electrical insulators are shown in Table 2 as Comparative Examples 5 to 7. Comparative Examples 8 to 9 Table 3 shows the results obtained by forming an electrical insulator on the outer peripheral surface of the conduit in the same manner as in Example 1, except that polyetheretherketone resin powder whose viscosity was outside the range of the present invention was used. The properties of the electrical insulators are shown in Table 3 as Comparative Examples 8 to 10.

【table】

【table】

[Table] As is clear from the results described in Tables 1, 2, and 3 above, the conduit coated with electrical insulation according to the present invention has electrical properties and mechanical properties. It also has excellent hot water resistance and is suitable as a conduit used for extracting hydrocarbon underground resources by electric heating.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical cross-sectional view of the distal end of a conduit coated with electrical insulation according to the present invention, and FIG. 2 is a partial vertical cross-sectional view of the joint of the conduit shown in FIG. 1... Electrode, 2, 2a and 2b... Conduit,
3, 3a and 3c...electrical insulating layer.

Claims (1)

[Claims] 1. A polyether ether ketone resin with a particle size of 10 to 100 μm and a melt viscosity of 1400 to 2000 poise at 380 °C is adhered to the outer peripheral surface of a metal conduit that has been preheated to 350 to 380 °C by electrostatic coating. 350～
A method for manufacturing a conduit for an electrode device for electric heating of hydrocarbon underground resources, characterized by being fused at 380°C.