JPS635555B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electrode device for electric heating of hydrocarbon underground resources, and more specifically,
This invention relates to an electrode device that is connected and supported at the lower end of a conduit and used when extracting underground hydrocarbon resources by electrical heating.

In the following description, underground hydrocarbon resources refer to bitumen contained in oil sands or tar sands, and are 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 was impossible to extract it 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 expensive, so a more productive method is to bury a conduit made of steel or stainless steel pipe that supports the electrode at the bottom end so that the electrode is located in the oil sand layer. Two such conduits are installed in parallel at an interval of about 30 to 200 meters, 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 oil level. A method of extracting oil by lowering its viscosity was proposed. In this case, since the resistivity of the oil sand layer is several times higher than that of the upper stratum, it is necessary to interpose an insulator between the conduit buried in the stratum and the electrode buried in the oil sand layer. If no insulator is used, current will flow through the strata and no current will flow between the electrodes buried in the oil sand layer. Accordingly, the demand for developing insulators that can withstand use under such special conditions is rapidly increasing.

Therefore, the above-mentioned insulator must have the following characteristics: (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; at least
It shall have a volume resistivity of 10 ⁶ Ω-cm.

(B) The water contained in the oil sand layer is heated to a temperature of approximately 300°C, which can reduce the viscosity of the oil sand layer, so it must be able to withstand hot water of approximately 300°C.

(C) It must have mechanical strength to allow the electrode to be suspended and mechanical impact strength to the extent that it will not be damaged by contact with the hole wall when the electrode suspended at the tip of the conduit is buried in the oil sand layer through the buried hole.

(D) To withstand a pressure of approximately 70 kg/cm ² caused by being buried 500 meters underground.

etc. are required.

This invention was made in view of the above circumstances, and aims to provide an electrode device for electric heating of hydrocarbon underground resources, which has an insulator with excellent voltage resistance, hot water resistance, and mechanical strength. It is something.

This invention will be described in detail below.

As a result of extensive research to develop an insulator that has all of the characteristics (A) to (D) above, the inventors of the present invention have developed a cylindrical conduit, which has the same inner diameter as this conduit and a conduit whose outer diameter is the same as that of the conduit. A coupling ring having a large-diameter cylindrical part larger than the outer diameter of the conduit at its upper end, which is larger than the outer diameter of the conduit and has a tapered screw at the lower end for connecting an electrode, and a lower end of the conduit inside the large-diameter cylindrical part of the coupling ring. The above-mentioned ( The present inventors have discovered that an electrode device for electric heating of hydrocarbon underground resources can be obtained that has all of the characteristics of A) to (D), and has completed the present invention.

The polyetheretherketone resin used in this invention is represented by the following chemical structural formula:
Examples include aromatic polyetheretherketones developed by the British company Imperial Chemical Industries.

As the composite material of polyetheretherketone resin and glass fiber, a composite material having a glass content of 30 to 70% by weight is used. In the case of composite materials with a glass content of less than 30% by weight, large stress is generated at the interface between the creeping insulator and the metal conduit and inside the creeping insulator due to the difference in expansion coefficient between the creeping insulator and the metal conduit.
The mechanical properties of the creeping insulation are reduced. A composite material with a glass content of more than 70% by weight has no water-blocking properties and has poor electrical properties as a creeping insulator.

As the metal conduit, a steel pipe or a stainless steel pipe, which has excellent corrosion resistance and excellent strength at high temperatures, is suitable.

Glass mica plastic is an insulation product made from a mixture of glass powder and mica powder, heated to a temperature where the glass softens and flows under pressure, and then pressure-molded in the heated state. It refers to things (see Japanese Patent Application No. 55-51151 for details).

Next, an embodiment of the invention shown in the drawings will be described. In the figure, the lower end of a cylindrical conduit 1 made of a metal material such as steel or stainless steel is fixedly connected to a large diameter tube portion 3a of a cylindrical coupling 3 by a coupling insulator 2 made of glass mica plastic. ing. The inner diameter of the coupling ring 3 is equal to the inner diameter of the conduit 1, and a tapered thread 3b for connecting an electrode (not shown) is formed at its lower end.
The coupling ring 3 and the conduit 1 are electrically insulated by a coupling insulator 2 made of glass-mica plastic. Furthermore, a creeping insulator 4 made of polyetheretherketone resin and glass fiber is formed on the outer surfaces of the coupling 3 and the conduit 1. If there is no creeping insulator 4, the creeping insulation distance between the coupling 3 and the conduit 1 will be short, and the electrical characteristics of the electrode device will deteriorate.

Next, the manufacturing process of the above insulator will be explained.
First, the coupling ring 3 and the conduit 1 were made in a patent application filed in 1983.
They are bonded by a bonding insulator 2 made of a glass mica plastic body by the method described in No. 51151. Then,
A prepreg tape made of polyetheretherketone resin and glass fiber with a glass content of 30 to 70% by weight is wrapped around the outer surfaces of the coupling ring 3 and the conduit 1, and the outer circumferential surface is held in a mold at a temperature of 350 to 450℃. The creeping insulator 4 is formed by heating and pressing at a pressure of 10 to 100 kg/cm ² to form a creeping insulator 4 made of a composite material of polyetheretherketone resin and glass fiber having a glass content of 30 to 70% by weight.

The insulator of the electrode device of the present invention having the above structure has good electrical and mechanical properties not only at room temperature but also after a 500-hour hot water test in 300°C hot water, and has excellent electrical and mechanical properties. This is suitable as a heating electrode device used for extracting underground hydrocarbon resources.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of one embodiment of the invention. DESCRIPTION OF SYMBOLS 1...Conduit, 2...Coupling insulator made of glass mica plastic body, 3...Coupling, 3a...Large diameter cylindrical part, 3b...Tapered screw, 4...Composite of polyether ether ketone resin and glass fiber Creeping insulation made of wood.

Claims (1)

[Claims] 1. A cylindrical coupling having a cylindrical conduit, a large-diameter cylindrical part whose inner diameter is equal to the inner diameter of the conduit, and a large diameter cylindrical part larger than the outer diameter of the conduit at its upper end, and a tapered screw for connecting an electrode to its lower end. and a bonding insulator made of a glass mica plastic body interposed between the inner wall of the large-diameter cylindrical portion and the lower end of the conduit;
An electrode device for electric heating of hydrocarbon underground resources, comprising a creeping insulator made of a composite material of polyetheretherketone resin and glass fiber and coated on the outer surfaces of the conduit and the coupling ring.