JPS6320997B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrode support conduit for electric heating of underground hydrocarbon resources, and in particular to an electrode support conduit for electric heating coated with an electrical insulator, which is used when extracting underground hydrocarbon resources by an electric heating method. It is. In this specification, hydrocarbon underground resources are
Refers to bitumen contained in oil sands or tar sands, and is referred to as oil sands below unless otherwise specified. In recent years, with the rise in the price of petroleum resources, extraction of oil from underground oil sand layers in countries such as Canada and Venezuela is being carried out in earnest. This oil sand layer is usually underground
It exists in a layer approximately 50m thick 100m deep underground, but due to its high viscosity, it cannot be extracted by pumping it up at room temperature. The method used was to raise the temperature of the oil by injecting it, lower its viscosity, and then pump it out. However, this method is inefficient and expensive, so a more productive method is to use a steel tube or stainless steel tube with an electrode section supported at the lower end.
A pair of conduits is buried underground at a distance of approximately 30 to 200 m, with the electrodes located in the oil sand layer, and a voltage of several hundred to several thousand volts is applied between the two electrodes to generate heat. proposed a method for extracting oil by increasing the temperature of the oil sand layer and lowering the viscosity of the oil sand layer. In this latter oil extraction method, the resistivity of the oil sand layer is several times higher than that of the upper stratum, so the part of the conduit buried in the stratum is coated with an electrical insulator to prevent current from flowing through the upper stratum. You must do so. If it is not coated with an electrical insulator, current will flow through the strata and no current will flow 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 insulator 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) In order to heat the water contained in the oil sand layer to a temperature of approximately 300℃ that can reduce the viscosity of the oil sand layer, (c) Mechanical strength to allow the electrode to be suspended, and mechanical strength to the extent that it will not contact the hole wall and cause damage when the electrode is supported and suspended at the lower end of the conduit and is buried in the oil sand layer through the buried hole. Must have impact strength. etc. are required. The present invention was made in response to the above requirements, and an object of the present invention is to provide an electrode support conduit for electrically heating hydrocarbon underground resources that has excellent voltage resistance, heat resistance, and mechanical strength. Another object of the present invention is to create an electrical insulator obtained by wrapping a glass fiber tape impregnated with polyetheretherketone resin multiple times around the outer circumferential surface of a metal conduit, pressing the outer circumference with a mold, and applying heat and pressure. An object of the present invention is to provide an electrode support conduit for electrical heating. This invention will be described in detail below. The present inventors have conducted extensive research to develop an electrode supporting conduit coated with an electrical insulator that has all the characteristics (a), (b), and (c) above, and as a result, the outer peripheral surface of the metal conduit A glass fiber tape impregnated with polyetheretherketone resin is wrapped around the tape by pultrusion molding or compression molding, and the outer circumference is held down using a mold at a temperature of 350 to 450℃ and a pressure of 10 to 200Kg/ ^cm2. By heating and pressurizing and molding under the conditions of (a) above,
It was discovered that an electrode support conduit coated with an electrical insulator having all of the characteristics listed in (c) above can be obtained, and the present invention was completed. Examples of the polyetheretherketone resin used in the present invention include aromatic polyetheretherketones developed by Imperial Chemical Industries Ltd. in the UK, which are represented by the following chemical structural formula. A glass fiber tape having a resin content of 30 to 70% by weight is used as a tape impregnated with polyetheretherketone resin by heating and melting by pultrusion molding or compression molding. Resin content is 30% by weight
When Suemitsu's tape is used, water absorption into the electrical insulator is large, reducing the volume resistivity of the electrical insulator. If a tape with a resin content of more than 70% by weight is used, the difference in expansion coefficient between the electrical insulator and the metal conduit will generate large stress at the interface between the electrical insulator and the metal conduit and inside the electrical insulator, causing electrical damage. The mechanical properties of the insulator are reduced. 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, but it is usually between 200 and 600 meters. Next, the manufacturing process of the electrode support conduit will be described. First, a glass fiber tape impregnated with polyetheretherketone resin by pultrusion molding or compression molding is wrapped several times around a metal conduit, and then the outer circumferential surface of the tape is wrapped around a metal conduit using a mold to give a weight of 10 to 200 kg/kg.
An electrical insulator is formed by applying pressure to a pressure of cm ² and heating to a temperature of 350-450°C to melt the polyetheretherketone resin and integrate the tape. If the heating melting temperature is lower than 350℃, the polyetheretherketone resin has a high melt viscosity, so air bubbles generated between the tapes will not come out, making it impossible to obtain an electrical insulator with excellent hot water resistance and electrical properties. I can't. heating melting temperature
If the temperature is higher than 450°C, thermal deterioration of the polyetheretherketone resin occurs, and an electrical insulator with excellent hot water resistance, mechanical properties, and electrical properties cannot be obtained. If the molding pressure is lower than 10 Kg/cm ² , air bubbles inside the electric insulator will not come out, making it impossible to obtain an electric insulator with excellent hot water resistance and electrical properties. If the molding pressure is greater than 200Kg/ ^cm2 , the polyetheretherketone resin will flow out as burrs from the gaps in the mold and the glass fibers will be cut, resulting in an electrical insulator with excellent hot water resistance, mechanical properties, and electrical properties. I can't. In addition, without relying on this invention, a tape made only of polyether ether ketone resin is wrapped around the outer peripheral surface ^of a metal conduit, and the polyether ether When forming an electrical insulator consisting of a film made of only ketone resin, the expansion coefficients of the polyetheretherketone resin film and the metal conduit are greatly different. Large stresses are generated within the coating, reducing adhesion and strength of the coating. In this way, a metal conduit with a coating made of only polyetheretherketone resin formed on the outer peripheral surface can be immersed in water at 25°C.
When repeated hot water cycles at 300°C, the polyetheretherketone resin coating either peels off from the surface of the metal conduit or cracks, making it impossible to put it to practical use. However, the outer peripheral surface of the metal conduit is heated and melted and impregnated with polyether ether ketone resin by pultrusion molding or compression molding.The resin content is 30 to 70%.
The electrical insulator according to the present invention, which is made by wrapping a glass fiber tape of 10% by weight and pressing the outer circumferential surface with a mold, and molding under heat and pressure at a predetermined temperature and pressure, has a small difference in expansion coefficient from that of a metal conduit. Due to its high strength, it can withstand hydrothermal cycles of 25°C and 300°C in water, making it suitable as an electrical insulator for electrode support conduits for electrical heating of oil sand layers. Next, an embodiment of the electrode support conduit of the present invention will be described with reference to the drawings. FIG. 1 shows the lower end of the electrode support conduit covered with an electrical insulator, and as shown in the figure, the above-mentioned electrical insulator 3 is coated on the outer peripheral surface of the metal conduit 2 whose lower end is to support the electrode 1. ing. Next, the coating conditions and properties of the insulator 3 shown in FIG. 1 will be explained in more detail by giving some examples and comparative examples, but the present invention is not limited only to these examples. do not have. Example 1 A silica glass fiber containing 90% silica is impregnated with polyetheretherketone resin, the polyetheretherketone resin content is 50% by weight, and the thickness is
A tape having a size of 0.2 mm and a width of 0.3 mm was wound eight times around the outer peripheral surface of the metal conduit 2 in a half-overlap manner to form a tape layer having a thickness of 3.2 mm. Next, the metal conduit 2 wound with this tape layer is placed in a mold divided into four parts, and a pressure of 50 Kg/cm ² is applied in an electric furnace at a temperature of 400°C to coat the metal conduit 2 with polyether ether. An electrical insulator 3 made of a composite of ketone resin and silica glass fiber containing 90% silica was formed. The adhesive strength Kg/cm ² and withstand voltage kV/mm at 25°C of the electrical insulator 3 obtained in this way and the electrical insulator 3 were placed in water and heated to 300°C.
After holding for 100 hours, the process of cooling to 25°C was one cycle, and after repeating 5 cycles of hot water cycles, the adhesion strength and withstand voltage value of the electrical insulator 3 measured at 25°C were determined according to Example 1 in Table 1. It is shown in the column. Examples 2 to 14 The configuration of the tape layer and the molding conditions were
An experiment was conducted in the same manner as in the example except for the changes shown in the table. An electric insulator made of a composite was formed on the outer peripheral surface of the metal conduit 2, and the characteristics of the obtained electric insulator 3 are shown in Table 1. This is shown as Examples 2 to 14. Comparative Examples 1 to 6 Experiments were conducted in the same manner as in Example 1 except for changing the configuration of the tape layer or the molding conditions. The properties of the electrical insulators obtained are shown in Table 1 as Comparative Examples 1 to 6. Comparative Example 7 A polyether ether ketone resin tape with a thickness of 0.05 mm and a width of 30 mm was wound around the outer circumferential surface of a metal conduit 30 times, and the outer circumferential surface was held down with a mold.
It is molded under heat and pressure conditions of 380℃ and 50Kg/cm ² to form an electrical insulator made only of polyetheretherketone resin on the outer peripheral surface of the metal conduit.Table 1 shows the characteristics of the obtained electrical insulator as a comparative example. 7.

[Table] As is clear from the results shown in Table 1, the electrical insulator 3 according to the present invention has the following properties after 5 cycles of hot water cycles at 25°C to 300°C: The minimum value is 170Kg/cm ² compared to the maximum value of 90Kg/cm ² in the comparative example, and the minimum value is 25kV/cm compared to the maximum value of 16kV/mm in the comparison example.
mm, which is extremely superior, and (a) ~
All of the characteristics in (c) can be satisfied. Generally, the length of the electrode support conduit is required to be approximately 200 to 600 m, but since the length of each ordinary steel pipe or stainless steel pipe is 5 to 50 m, the electrode support conduit is required to be placed in the oil sand layer. When inserting the tip, insert the electric insulator 3 into the
The method used is to insert 50m of metal conduits while connecting them one after another. Figure 2 shows the connections between metal conduits coated with electrical insulators, as shown in the figure.
When connecting the metal conduits 2a and 2b coated with the electrical insulator 3, a taper thread 5 is cut at the end of each of the metal conduits 2a and 2b, and a coupling ring 4 having a similar taper thread is used to screw the metal conduits 2a and 2b together.
In this case, a similar electrical insulator 3a is further coated over the connection, ie the surface of the coupling 4 and the end of the conduit, in order to prevent electrical leakage from the connection. As is clear from the above description, the electrode support conduit coated with the electrical insulator of the present invention has excellent electrical properties, mechanical properties, and hot water resistance, and the electrical heating method allows the electrode support conduit to be heated underground. It is particularly effective as an electrode support conduit for electrical heating used in resource extraction.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical sectional view of an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing the connection structure of FIG. 1. 1... Electrode, 2, 2a, 2b... Metal conduit, 3, 3
a... Electrical insulator, 4... Coupling, 5... Taper screw. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1 A metal conduit and a glass fiber tape impregnated with polyetheretherketone resin are wrapped around the outer peripheral surface of the metal conduit multiple times at a temperature of 350 to 450°C and a pressure of 10 to 200 kg/cm ² . An electrode support conduit for electric heating of hydrocarbon underground resources, characterized by comprising an electric insulator formed by heating and pressurizing under certain conditions. 2. The electrode supporting conduit for electric heating of hydrocarbon underground resources according to claim 1, wherein the polyetheretherketone resin content of the tape is in the range of 30 to 70% by weight.