JPS6245396B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing an electrode support conduit for electrical heating of hydrocarbon underground resources, and in particular, an electrode support conduit coated with electrical insulation and used for extracting hydrocarbon underground resources by an electrical heating method. The present invention relates to a method of manufacturing a conduit. 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 petroleum resources, extraction of oil from oil sand layers buried underground in countries such as Canada and Venezuela is being carried out in earnest. 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 sand layer to raise the temperature of the oil, lower its viscosity, and then pump it. However, this method is inefficient and costly, so a more productive method is to bury a conduit made of steel or stainless steel pipe with an electrode section at the lower end so that the electrode section is located in the oil sand layer. Two such 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 lowers 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. No. if,
If not covered with an electrical insulator, current will flow through the strata.
Current no longer flows between the electrodes buried in the oil sand layer. Accordingly, there is a rapidly increasing need to develop electrode support conduits coated with electrical insulators that can withstand use under these special conditions. The characteristics that such an electrical insulating coating must have are: (A) Voltage resistance of several hundred to several thousand volts not only at room temperature but also at temperatures of approximately 300°C, which can reduce the viscosity of oil in the oil sand layer. and 10 ⁶ Ω-cm
(B) Hot water at approximately 300°C because the water contained in the oil sand layer is heated to a temperature of approximately 300°C that can reduce the viscosity of the oil sand layer. (C) Mechanical strength that allows the electrode to be suspended, and mechanical strength that will not cause damage due to contact with the hole wall when the electrode suspended from the lower end of the conduit is buried in the oil sand layer through the buried hole. have the desired impact strength. etc. are required. This invention was made in response to the above requirements, and an object thereof is to provide a method for manufacturing an electrode support conduit for electric heating of hydrocarbon underground resources that has excellent voltage resistance, heat resistance, and mechanical strength. It is. This invention will be described in detail below. The present inventors have conducted extensive research to develop an electrode support conduit coated with an electrical insulator that has all of the characteristics (A) to (C) above. Etherketone resin film and glass fiber containing 90% or more of silica are alternately wrapped around each other, and the outer periphery is pressed using a mold.
By melting and molding polyetheretherketone resin under heat and pressure at 350 to 450℃ and 10 to 200Kg/ ^cm2 , an electrical insulator having all of the characteristics of (A) to (C) above is coated. The present inventors have discovered that an electrode supporting conduit can be obtained, and have completed the present invention. The polyetheretherketone resin used in the present invention is represented by the following chemical structural formula and includes, for example, aromatic polyetheretherketones developed by British Imperial Chemical Industries. Polyetheretherketone resin has a thickness of
A film of 0.01 to 0.20 mm, preferably 0.02 to 0.10 mm is used. If the film is less than 0.01 mm thick, the tension applied to avoid creating gaps between the layers of the film or between the layers of the glass fiber may cause the film to break, making it difficult to wind the film around the metal conduit. I can't attach it. If the film is thicker than 0.20 mm, the elastic repulsion force of the film is large and it is not possible to wrap the film layers closely, resulting in gaps between the film layers and between the film and glass fiber layers. During heating and pressure molding, air bubbles are incorporated into the insulator, making it impossible to obtain an insulator with excellent hot water resistance and electrical properties. As the glass fiber, glass fiber containing 90% or more of silica is used. If the silica content of the glass fiber is less than 90%, the surface of the glass fiber will be dissolved by hot water at 300°C, reducing the volume resistivity and mechanical strength of the electrical insulator. As the metal conduit, a steel pipe or a stainless steel pipe having excellent corrosion resistance and good electrical conductivity is suitable. The length of the conduit is determined depending on the depth of the underground oil sand layer.
Usually about 200 to 600 m is required. Next, the manufacturing process of the electrode support conduit will be described. First, a polyetheretherketone resin film and glass fiber containing 90% or more of silica are alternately wrapped around a metal conduit, and then the outer circumferential surface is applied with a pressure of 10 to 200 kg/cm ² using a mold. An insulating coating can be formed by pressing and heating to a temperature of 350 to 450°C to melt the polyetheretherketone resin and integrate it with the glass fiber. When the heating melting temperature is lower than 350℃, the melt viscosity of the polyetheretherketone resin is high, and the polyetheretherketone resin is not impregnated to the inside of the glass fiber, resulting in an insulating coating with excellent hot water resistance and electrical properties. I can't. If the heating melting temperature is higher than 450° C., thermal deterioration of the polyetheretherketone resin occurs, and an insulating coating with excellent hot water resistance, mechanical properties, and electrical properties cannot be obtained. If a polyether ether ketone resin film is directly wrapped around the outer peripheral surface of a metal conduit and heated and melted at 350 to 450°C to form a polyether ether ketone resin film, it is possible to Since the expansion coefficients of the ether ether ketone resin coating and the metal conduit are significantly different, a large internal stress is generated at the fusion surface of the metal conduit and the coating, resulting in a decrease in adhesion. In this way, when a film of only polyether ether ketone resin is formed on the outer circumferential surface of a metal conduit, when a hydrothermal cycle of 25°C and 300°C is repeated in water, the polyether ether ketone resin film forms on the metal pipe. It peels off from the surface and cannot be put to practical use. However, polyetheretherketone resin films and glass fibers containing 90% or more of silica are alternately wrapped around the outer circumferential surface of a metal conduit, and the outer circumferential surface is held in a mold and heated and pressed at a predetermined temperature and pressure. The molded insulating coating according to the present invention has a small difference in expansion coefficient from that of the metal conduit, and has high strength, so it can withstand hydrothermal cycles of 25°C and 300°C in water, and is suitable for oil sand layer heating electrodes. It is suitable as an insulator for the conduit of the device. Next, embodiments of the electrically insulating coated electrode support conduit of the present invention will be described with reference to the drawings. FIG. 1 shows the lower end of an electrode support conduit 1 coated with electrical insulation, and a metal conduit 3 to which an electrode 2 is coupled and supported.
An insulating coating 4 formed by the method described above is provided on the outer peripheral surface of the holder. In addition, the length of the metal conduit 3 is generally about 200 to 600 m.
However, since the length of each ordinary steel pipe or stainless steel pipe is 5 to 50 m, when inserting the lower end into the oil sand layer,
Insert individual conduits while sequentially joining them. FIG. 2 shows a joint of a metal conduit coated with electrical insulation, and shows a metal conduit 3a provided with an insulation coating 4a and an insulation coating 4b.
When joining the metal conduits 3b provided with the metal conduits 3a and 3b, taper screws 5 are cut at the ends of each of the metal conduits 3a and 3b, and a coupling ring 6 is used to join the metal conduits 3a and 3b. In that case, to prevent electrical leakage from the joint,
That is, an insulating coating 4c is further provided over the surface of the coupling ring 6 and the end of the metal conduit. Next, the coating method and properties of the insulating coating 4, 4a, 4b, or 4c will be explained in more detail with reference to data of examples and comparative examples, but the present invention is not limited only to these examples. . Example 1 A tape made of polyether ether ketone resin film with a thickness of 0.05 mm and a width of 30 mm was wrapped in two halves.
2 times, wrapped around the outer circumferential surface of the metal conduit, and then
A glass fiber tape having a silica content of 90% or more and having a size of 0.20 mm and a width of 30 mm was wound once in a half-overlap manner. This process of winding the polyetheretherketone resin film tape and the glass fiber tape was repeated four more times, for a total of five times, and then a layer of 0.05
A polyetheretherketone resin film with a width of 30mm and a width of 30mm was wound twice to form a composite layer of polyetheretherketone resin and glass fiber with a thickness of 3.2mm on the outer peripheral surface of the metal conduit. Next, the metal conduit wound with this composite layer was placed in a mold divided into four parts and held down, and a pressure of 50 kg/cm ² was applied in an electric furnace at 380°C.
A composite insulation coating made of polyetheretherketone resin and glass fiber containing 90% or more of silica was formed on the conduit. Adhesive strength (Kg/cm ² ) and withstand voltage (kV/mm) at 25°C of the insulating coating obtained in this way, and the insulation coating was placed in water and heated to 300°C, and then immersed in hot water at 300°C for 10 hours. After holding, the process of cooling to 25℃ is 1
The adhesion strength and withstand voltage values measured at 25°C after 5 cycles of hot water cycles are shown in the Example 1 column of Table 1. Examples 2 to 8 Experiments were conducted in the same manner as in Example 1 except that the composition and molding conditions of the composite insulating layer were changed to those shown in Table 1, and an electrically insulating coating was formed on the outer peripheral surface of the metal conduit. The properties of the obtained insulation coatings are shown in Table 1 as Examples 2 to 8. Comparative Examples 1 to 4 Experiments were conducted in the same manner as in Example 1 except that the composition or molding conditions of the composite insulating layer were changed, and an insulating coating was formed on the outer peripheral surface of the metal conduit under conditions outside the scope of the present invention. The properties of the obtained insulation coating are shown in Table 1 for Comparative Example 1.
Shown as ~4. Comparative Example 5 A polyether ether ketone resin film tape with a thickness of 0.05 mm and a width of 30 mm was wound 30 times around the outer circumferential surface of a metal conduit, the outer circumferential surface was pressed with a mold, and the tape was heated at 380°C and 50 kg/cm. It was molded under the heating and pressurizing conditions of ² to form an insulating coating of only polyether ether ketone resin on the outer peripheral surface of the metal conduit, and the properties of the obtained insulating coating are shown in Table 1 as Comparative Example 5. Comparative Examples 6 to 9 Experiments were conducted in the same manner as in Example 1, except that a glass fiber tape with a silica concentration of less than 90% was used instead of a glass fiber tape with a silica content of 90% or more.
The properties of the obtained insulation coatings are shown in Table 2 for Comparative Examples 6 to 9.
Shown as

【table】

[Table] As is clear from the results shown in Tables 1 and 2, the electrode support conduit having an electrically insulating coating formed according to the present invention has electrical properties,
It has excellent mechanical properties and hot water resistance, and has the advantage of being suitable as an electrode support conduit used for extracting hydrocarbon underground resources by electric heating.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical sectional view of the lower end of an electrode support conduit coated with electrical insulation according to the present invention, and FIG.
FIG. 3 is a longitudinal cross-sectional view of the junction of the electrode support conduit shown in the figure; 1... Electrode support conduit, 2... Electrode, 3, 3a,
3b...metal conduit, 4, 4a, 4b and 4c...
…Insulation coating, 5…Tapered screw, 6…Coupling.

Claims (1)

[Claims] 1. Polyetheretherketone resin film and glass fiber containing 90% or more of silica are alternately wrapped around the outer circumferential surface of a metal conduit several times, and the outer circumference is pressed with a mold to form a 350 to 450 A method for manufacturing an electrode supporting conduit for electric heating of hydrocarbon underground resources, characterized in that an insulating coating is formed by heating and press forming at a temperature of 10 to 200 Kg/ ^cm2 . 2. The method for manufacturing an electrode support conduit for electric heating of hydrocarbon underground resources according to claim 1, wherein the polyetheretherketone resin film has a thickness in the range of 0.01 to 0.20 mm.