JPS6311518B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electrode device for electrically heating hydrocarbon-based underground resources, and more specifically, it relates to an electrode device for electrically heating hydrocarbon-based underground resources. The present invention relates to an electric heating electrode device used to supply electricity to and heat a hydrocarbon-containing layer located underground in order to improve the fluidity of hydrocarbons.

Typical hydrocarbons with high viscosity and low fluidity that exist underground include bitiumen contained in what is generally called oil sand or tar sand, and kerogen contained in what is called oil shale. Of these, currently
Oil sands are the focus of research from an economic standpoint. The methods currently being researched to actually heat underground oil reservoirs include burying a steel casing that reaches the underground oil reservoir and injecting hot water or high-temperature, high-pressure steam.
This is a method in which two electrodes are buried in the oil layer with an appropriate distance between them, and electricity is applied between the electrodes to heat the oil layer using Joule heat. The former method has the advantage of being easy in terms of equipment, but has the disadvantage of being inefficient. Although the latter method has been theoretically and experimentally recognized to be very efficient, it has the disadvantage of being extremely difficult to use in terms of equipment.

The present invention relates to an electrode device used in the latter so-called electric heating method. It is impossible to extract underground oil sands using electric heating methods alone. In the case of the electric heating method, a tubular electrode device is installed at the bottom of the casing, and after electricity is applied to reduce the viscosity of the oil, high-temperature, high-pressure steam is injected through one casing, and oil is collected through the other casing. Be taken.

In order to facilitate understanding, characteristics required of the electrode device will be described below, including the state of existence of oil sands and the method of collection. Oil sand reserves have been confirmed in Canada, the United States, Venezuela, etc. Oil in oil sands exists along with salt water on the surface of the sand and in the gaps between the sands, but it has extremely high viscosity and has no fluidity in its natural state. The oil sand layer is partially exposed in canyons and riverbanks, but most of the oil sand layer exists at a depth of 200 to 500 meters underground, forming a layer several tens of meters thick. Excavating oil sands and separating the oil above ground is limited by economics and environmental protection, so it is necessary to extract only the oil from underground. In addition, extracting oil from shallow underground layers may cause the layers to cave in, so
It is said that it is desirable to collect from a layer below 300m.

The biggest problem with an electrode device that heats an oil sand layer by energization is that the electrical resistance of the oil sand layer is higher than that of the stratum above the oil sand layer, that is, the upper layer of the oil sand layer. Although it is difficult to express it uniformly because it differs depending on the location and other conditions, if we show the average value,
The oil sand layer is 100Ωm, and the upper stratum is
It is 10Ωm. Therefore, if electrodes are supported at the lower end of a casing made of steel pipes and a pair of electrodes is buried in the oil sand layer and energized, most of the current will be consumed in the upper stratum. In order to avoid this phenomenon, it is necessary to provide an insulating coating layer on the surface of the casing in the strata, or to insulate the electrode from the casing.

The present invention relates to the latter device, and this device will be explained below.

If this device is shown schematically, the electrode devices are arranged as shown in FIG. That is, electrodes 3 and 13 are supported by casings 1 and 11 made of steel pipes via insulating parts 2 and 12, and cables 4 and 14 for transmitting current are connected to the electrodes 3 and 13 to constitute an electrode device. ing. 5 is a power supply device, 6 is an oil sand layer, 7 is a current between electrodes 3 and 13, 8 is a ground surface, 9 is an upper oil sand layer, and 10 is a lower oil sand layer. With this device, when a voltage is applied to the electrodes 3 and 13 buried in the oil sand layer 6 from the ground power supply 5 through the cables 4 and 14, a current 7 flows according to the electrical resistance in the oil sand layer 6. Joule heat is generated and the oil sand layer 6 is heated. At this time, part of the current 7 also flows to the upper oil sand layer 9 and the lower oil sand layer 10, but the casings 1 and 11 and the electrodes 3 and 13
Since the insulating parts 2 and 12 are interposed between them, the leakage of the current 7 can be suppressed to a small level. When the oil sand layer 6 warms up, the electricity is turned off, and hot water or high-temperature, high-pressure steam is injected from the upper part of the casing 1 on one side of the electrode device.
It passes through the inside and flows out from the other casing 11 together with the oil. In order to improve the outflow of hot water or high-temperature, high-pressure steam, the electrodes 3 and 13 are usually provided with a large number of pores.

Salt water is normally fed into the electrode device through a pipe (not shown) in order to lower the contact resistance between the electrodes 3 and 13 and the oil sand layer 6, and to separate the salt water and the casings 1 and 11. electrode 3,
A partition plate (not shown) is provided above 13, and the upper part of the partition plate is filled with an insulating liquid.

Such electrode devices do not break when buried, and have sufficient strength to withstand earth pressure when buried, but when energized, the temperature rises, and the temperature rise is especially significant near the electrodes due to the high current density. However, it is still required to not deform or break, to withstand the static pressure of the liquid filled inside, and to not break or leak when hot water or high-temperature, high-pressure steam is injected. By the way, if it is buried 500m underground, the specific gravity of the liquid filled inside is 1, then it is 50Kg/cm ²
The temperature of steam with a pressure of 50 Kg/cm ² reaches 265°C.

Since the upper parts of the insulating parts 2 and 12 are connected to the casings 1 and 11 and the lower parts to the electrodes 3 and 13, a suspended load is always applied to the insulating parts 2 and 12, and the conditions are 250 Since the temperature is high at ~300°C, characteristics that meet this requirement are required.
Next, the insulating parts 2, 12 have electrodes 3, 13 at their lower ends.
is suspended, and the upper end is connected to the casings 2 and 12, and is installed several hundred meters underground, so it may come into contact with the hole wall of the stratum during the installation process.
In reality, collision becomes an unavoidable condition.
Therefore, since the overall weight is heavy, even a slight contact causes a large mechanical impact on the insulating parts 2 and 12, and the insulation parts 2 and 12 are required to have characteristics that can withstand this impact and not be damaged.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrode device for electrically heating hydrocarbon-based underground resources that satisfies the above-mentioned characteristics.

First, the present inventors conducted research on an insulated pipe joint used in a useful electric heating electrode device. The following items were listed as characteristic goals. In other words, the electrodes are held suspended, so the mechanical strength is high; a voltage of 4,000 to 5,000 V is applied between the two electrodes, so the device must have high withstand voltage characteristics that can withstand this voltage; and the temperature rises due to the current flowing between the electrodes. The temperature is approximately 300°C, but even under this temperature condition, the mechanical and electrical properties must be maintained, the material must have excellent cold and thermal shock resistance, and since contact with the hole wall will inevitably occur during burying, the mechanical casings 1, 11 and electrodes 3 above the diameter of the central through hole;
The flow resistance should be low, as is the inner diameter of No. 13. In addition,
Under the above conditions, the upper and lower casings 1 and 11 and the electrode parts 3 and 1 have a high degree of water (oil) tightness and no deterioration over time and have long-term reliability.
3 and can be easily connected.

An example of this insulated pipe joint 100 will be explained with reference to FIG. Figure a shows the product structure, which includes an internal fitting 21 and an external fitting 22, each made of steel and having a through hole in the center, and an insulator 2 interposed in the gap between them.
4. The inner metal fitting 21 has an outer circumferential ring 21-1 formed at its lower end. External metal fittings 2
2 is composed of an upper metal fitting 22-1 and a lower metal fitting 22-2, and the upper metal fitting 22-1 has an inner ring 22-3 at its upper end that faces the outer ring 21-1 of the inner metal fitting 21.
is formed. After this inner ring 22-3 penetrates the outer periphery of the wall 21-2 of the internal fitting 21, its lower end is connected to the outer periphery of the wall 22-4 of the lower fitting 22-2 by screwing or welding. 25. Note that the inner diameter of the wall portion 22-4 is larger than the diameter of the through hole of the internal fitting 21. The insulator 24 fills the gap between the internal fitting 21 and the external fitting 22, and continues from the wall 21-2 of the internal fitting 21.
and the inner circumferential surface of the wall portion 22-4 of the external fitting 22.

Next, as for the insulator 24, a glass/mica plastic body is used. This glass/mica plastic body is made from a mixture of glassy powder and mica powder.This raw material powder is heated to a temperature where the glassy material softens and can flow under pressure. It is an insulator made by molding.

This insulated pipe joint has an inner metal 3 having the shape shown in Fig. 2b.
1. Prepare the outer metals 32 and 33, use a special mold (not shown) to mold the insulator 24 made of the above-mentioned glass-mica plastic body, and then perform machining to form the insulator 24 shown in FIG. 2a. It is finished and manufactured into a product. The glass-mica plastic body used has a coefficient of thermal expansion below the glass transition temperature that is smaller than that of the steel material constituting each metal fitting. The temperature during molding is higher than the transition temperature of glass for both the metal fittings and the glass/mica plastic body, so during the cooling process after molding, the outer peripheral surface of the glass/mica plastic body is strengthened by the outer metals 32 and 33 present on the outer periphery. It is tightened. Next, when the temperature rises, the clamping force on this surface decreases, but conversely, the inner circumferential surface of the glass-mica plastic body becomes more strongly tightened by the outer circumferential surface of the inner metal 31 located inside.

In this insulated pipe joint 100, the inner fitting 21 has an outer circumferential ring 21-1, and the outer fitting 22 has an inner circumferential ring 22-1.
3, and both have metal fittings on the inner and outer circumferential surfaces of the insulator 24, so there is no possibility of loosening due to rises and falls in temperature. Therefore, in the temperature range from room temperature to 300℃, water (oil)
Not only the density properties but also the mechanical strength do not deteriorate. Moreover, the outer circumferential ring 21- of the internal fitting 21
1 and the inner circumferential ring 22-3 of the external metal fitting 22 face each other, so the suspension load strength is also extremely high. lastly,
The connection between the casings 1 and 11 and the electrode parts 3 and 13 is extremely easy since screws 23-1 and 23-2 are provided on the inner surfaces of the inner metal fitting 21 and the outer metal fitting 22, respectively.

As is clear from the above explanation, this insulation pipe joint 1
00 has most of the characteristics necessary as an insulated pipe joint for an electrode device, but it has an unavoidable defect in creeping insulation characteristics.

In the first place, in this electrode device, saline water is fed through a pipe in order to lower the contact resistance between the electrode and the oil sand layer as described above. For this reason, the saline solution also exists on the outer periphery of the insulated pipe joint, so it is necessary to form a long creeping insulation part on the outer periphery to ensure high creeping insulation properties. Regarding the inner circumferential surface, a partition plate 30 shown in FIG. Therefore, there are no defects that would pose a problem regarding the creeping insulation resistance of the inner circumferential surface.

Now, the creeping insulation characteristics of the outer circumference of this insulated pipe joint 100 are determined by the length of the insulator 24-1 formed on the outer circumferential surface of the wall portion 21-2 of the internal fitting 21.
There is naturally a limit to the length that can be constructed, and the limit is approximately 1/2 of its inner diameter. The reason is mainly due to the problem of moldability, and since a huge amount of molding equipment is required to break through this barrier, when considering the cost as well, the above-mentioned limit is suppressed.

The electrical heating electrode device of the present invention provides the above-mentioned insulated pipe joint 100 having various extremely excellent characteristics.
By taking advantage of this and securing the creeping insulation characteristics of the outer surface by other means, it is possible to achieve a structure that has all the required characteristics. Specifically, two insulated pipe joints 1
The internal fittings 21 of the insulated pipe fittings 100 are made to face each other, and an insulating tube with an insulating layer formed on the outer peripheral surface of the metal tube is joined and interposed between them, so that the insulation layer and the insulation on the outer peripheral surface of the internal fitting 21 of the insulated pipe fitting 100 are interposed. Another insulating layer is formed between the layers 24-1 to connect the two to ensure creeping insulation properties on the outer peripheral surface.

In realizing the above idea, the first problem is to obtain an insulating tube having an insulating layer firmly adhered to the outer circumferential surface. Usage conditions are room temperature to
In the case of a temperature range of about 100℃, it is possible to easily obtain the desired product by constructing an organic insulating layer that has corrosion resistance, etc., but if the usage conditions are 300℃ like this electrode device, As the situation progresses, things change dramatically. First, it is necessary to select a material that maintains heat resistance properties of 300°C. Among organic materials, materials that maintain the above characteristics are found, such as polyfluorinated ethylene (Teflon) and polyetheretherketone (Peak). The coefficient of thermal expansion of these materials is an order of magnitude different from that of the base steel pipe material, and when the temperature rises, flexible materials such as polyfluoroethylene deform significantly, and non-flexible materials such as polyether ether ketone develops into a destructive phenomenon. If the shape is small and the absolute amount of the difference between expansion and contraction is small, there may be a way to avoid this phenomenon, but as the shape becomes larger in terms of diameter, length, etc., the absolute amount of the difference between expansion and contraction becomes smaller. becomes larger. This is an inevitable physical phenomenon, and it is essentially impossible to avoid it. In the case of this electrode device, the diameter is 200~250mm and the length is 1~2mm.
Since a material of the order of m is required, the structure of the insulating layer made of the above organic material is completely unthinkable.

In the case of an insulated steel pipe that has an insulating layer on its outer circumferential surface that does not cause peeling or damage in the temperature range of room temperature to 300°C, the coefficient of thermal expansion of the insulation in the temperature range of room temperature to 300°C is similar to that of the steel pipe. That becomes a necessary condition. It satisfies this essential condition regarding the coefficient of thermal expansion, maintains electrical and mechanical properties in the temperature range from room temperature to 300°C, has excellent cold and thermal shock resistance, and has excellent corrosion resistance and long-term reliability. When it comes to insulating materials, the range of choices is extremely limited.

The electrode device of the present invention includes the above-mentioned insulated pipe joint 100.
An insulating tube is used in which the glass/mica plastic material used for the insulator is formed as an insulating layer on the outer surface of the steel tube. FIG. 3 shows an example of an insulating tube 101, in which a covering insulator 27 is formed on the outer circumferential surface of a metal tube 26, and a screw 23-1 for threading connection to a screw 23-1 of an internal fitting 21 of an insulating tube joint 100 is provided. 3 are provided at both ends of the metal tube 26. In this insulating tube 101, a steel material with a coefficient of thermal expansion of 11.8×10 ^-6 is used for the metal tube 26, and a steel material with a coefficient of thermal expansion of 11.5×10 ^-6 from room temperature to 400° C. is used for the covering insulator 27.
A glass/mica plastic body is used. As described above, since the coefficients of thermal expansion of the metal tube 26 and the insulator 27 are very similar to each other, the insulator 27 does not peel off or break when the temperature rises or falls from room temperature to 300°C. . The coefficient of thermal expansion of the glass-mica plastic body constituting the covering insulator 27 is higher than that of the insulator 24 of the insulating pipe joint 100. This can be obtained by using a material glass with a large coefficient of thermal expansion. Note that a coating insulator 27 is provided on the outer peripheral surface of the metal tube 26.
By providing a plurality of annular collar portions 26-1 so as to be embedded in the insulating material 27, the covering insulator 27 can be fixed more stably.

Next, the structure of the insulator that connects the insulator 24-1 of the insulating pipe joint 100 shown in FIG. 2 and the covering insulator 27 of the insulating tube 101 shown in FIG. 3 becomes a problem. An example of the configuration will be described below with reference to FIG. 4. The insulating tube 101 has a covering insulator 27 made of glass/mica plastic formed on the surface of the steel tube 26, and the inner fitting 21 of the insulating pipe joint 100 is attached to the end of the insulating tube 101.
A screw 23-3 is screwed into the wall portion 21-3 of the internal fitting 21 at the base of the screw 23-3.
A planar step portion 26-2 is formed opposite to the end faces of the insulator 24-1. The connecting portion 102 between the insulator 24-1 and the covering insulator 27 is formed by a screw 23-1.
The wall portion 21-2 of the insulated pipe joint 100 and the end face of the insulator 24-1 and the steel pipe 2 of the insulated pipe 101 are screwed together.
A gap is formed between the end face 26-2 of the insulator 6 and the covering insulator 27, and the gap is filled with an organic insulating material 28. Polyfluorinated ethylene or the like is preferably used as this insulating material. A portion of this insulating material 28 overflows to the outer circumferential surface, and the outer circumferential portion thereof is tightened by a metal tightening ring 29.

An embodiment of the electrical heating electrode device constructed as described above will be described with reference to FIG. In the figure 1
-4 are the same as those in FIG. 30 is electrode 3
It is a partition plate installed on the top of the. This electrode device uses 1002 insulated pipe joints, and the casing 1 and electrode 3 are connected to each external fitting 22 by screws 23-2.
and facing insulated pipe joints 10
The insulating tube 101 is attached to the internal fitting 21 of 0 with the screw 23-
The structure is such that they are interposed and connected by 1. This structure ensures complete insulation between the casing 1 and the electrode 3. Next, the creeping insulation properties on the outer circumferential surface required for this electrode device are as follows: The insulating tube 101 interposed between the two insulating pipe joints 100 has a covering insulator 27 made of glass-mica plastic on the outer circumferential surface.
The gap between the end face of the covering insulator 27 and the end face of the outer peripheral insulator 24-1 of the insulating section 100 is filled with an insulating material 28 made of an organic material, and the outer periphery of the overflowing insulating material 28 is covered with metal. Since it is tightened by the tightening ring 29 of
7 are connected to each other with complete insulation maintained by the insulating material 28, so that the creeping insulation properties of the outer circumferential surface are completely ensured.

As described above, the present invention provides an insulated pipe joint 100
An organic material with a large coefficient of thermal expansion is used to connect the insulating layers 24 and 27 on the outer periphery of the insulating tube 101 to ensure creeping insulation properties, but the gap is narrow and the amount of filling is small, causing expansion. , the absolute amount of shrinkage is small, and the outer periphery is tightened with a tightening ring 29,
By providing a buffering effect, complete water (oil)
The tightness is maintained and the desired creeping insulation properties are ensured.

In addition, necessary properties other than the creeping insulation properties of the outer peripheral surface, such as electrical insulation properties, mechanical impact strength, suspension load strength, and corrosion resistance properties, are ensured by the insulated pipe joint 100.

The embodiment shown in Fig. 5 has a configuration of two insulated pipe joints and one insulated pipe, but if necessary,
The creeping insulation resistance can be further increased by increasing the number of connections. In addition, although the casing, insulated pipe joints, insulated tubes, and electrodes are all connected by screws, they can be joined by welding, etc., and there is no problem in terms of performance and the assembly is less difficult. , the choice should be made considering economic efficiency.

As described above, the present invention stably maintains various properties including creeping insulation properties, is extremely useful as a device for underground resource recovery, and has extremely large economic and technical effects.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing how a conventional device is used, and Fig. 2 shows an embodiment of the insulated pipe joint used in the present invention. FIG. 3 is a vertical cross-sectional view showing one embodiment of an insulating tube used in the present invention, and FIG. FIG. 5 is a vertical cross-sectional view showing an embodiment of the present invention. In the figure, 1 and 11 are casings, 2 and 12 are insulating parts, 3 and 13 are electrodes, 4 and 14 are cables, 5 is a power supply, 6 is an oil sand layer, 21 is an internal metal fitting, and 21-1 is an outer ring , 21-2 is a wall part, 22 is an external metal fitting, 22-1 is an upper metal fitting, 22-2 is a lower metal fitting, 22-3 is an inner peripheral ring, 22-4 is a wall part, 23
-1 is 23-2, 23-3 is screw, 24, 24-
1 is an insulator, 25 is a joint, 26 is a metal tube, 27
is a covering insulator, 28 is an insulating material, 29 is a tightening ring, 3
0 is a partition plate, 100 is an insulated pipe joint, 101 is an insulated pipe, and 102 is a connecting portion. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. An electric heating electrode device in which an electrode is coupled and supported at the lower end of a casing made of a steel pipe via an insulating part, comprising: an inner metal fitting that is a hollow cylinder and has an outer peripheral ring formed at one end; an external fitting that is cylindrical and has an inner circumferential ring opposite to the outer circumferential ring formed at one end; and a gap between the external fitting and the internal fitting to the outer circumferential surface of the internal fitting and the inner circumferential surface of the external fitting. an insulated pipe joint comprising a glass-mica plastic molded insulator; an insulating pipe joint comprising a metal tube having an outer circumferential surface covered with a glass-mica molded insulator; The internal fittings of the insulated pipe joint are joined together, and an insulating material made of an organic substance is filled and overflows to the outside into the gap between the joints, and a metal tightening ring tightens the outer circumference of the overflowing insulating material. An electrode device for electrically heating hydrocarbon-based underground resources, characterized by comprising an insulating part. 2. An electrode device for electrically heating hydrocarbon-based underground resources according to claim 1, which includes a plurality of insulating parts. 3. The electrode device for electrically heating hydrocarbon-based underground resources according to claim 1, wherein the organic insulating material is polyfluoroethylene.