JPS6260559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrode device used for electrically heating hydrocarbon underground resources. More specifically, when producing hydrocarbons with high viscosity and low fluidity that exist underground from wells, an electrode device is used to heat and energize the underground in order to increase the fluidity of the hydrocarbons. It is related to.

"Hydrocarbons" here refer to petroleum or oil, bitumen contained in oil sands (also called tar sands),
It refers to kerogen contained in oil shells, and for the sake of simplicity, these hydrocarbons will be referred to as oil below. In addition, “production” refers to artesian,
Refers to the extraction of fluid oil from an oil well, such as pumping or fluid transfer.

If the oil existing underground has fluidity, a well is dug to reach the oil layer from the surface of the earth, and a liquid such as salt water is pumped out by self-injection using the pressure of the gas coexisting in the oil layer, pumped up, or liquid such as salt water is pumped from one well. It is possible to produce oil by injecting it into one well and letting it flow out of the other well. However, if the fluidity of underground oil is low, production cannot be achieved unless measures are taken to make the oil fluid. A common method for fluidizing oil is to reduce the viscosity of the oil by heating.The temperature suitable for fluidizing varies depending on the individual properties of the oil, but
It becomes necessary to heat the underground oil layer.

Possible methods for heating oil layers include injection of hot water, injection of high-temperature, high-pressure steam, underground electrification, underground combustion (igniting the underground oil layer and blowing air to burn it), and the use of explosives. , the latter two are difficult to control and lack generality.

Hot water or high-temperature, high-pressure steam injection methods can heat the oil layer to increase the fluidity of the oil and at the same time allow the fluidized oil to flow to the surface, but there are places in the oil layer with low passage resistance, such as cracks. If this happens, there is a risk that the oil will pass through only that area and not diffuse throughout the area.On the other hand, if the oil layer is hard and dense, hot water or steam will not diffuse and the temperature will be difficult to rise.

The current heating method involves drilling multiple wells in an oil layer, installing electrodes in these wells, and applying a potential difference between each electrode to heat the oil layer using the conductivity of the oil layer. Even if it is dense, it has the advantage of being easy to heat the whole. However, other means are required to remove the fluidized oil.

Therefore, as a method to increase the efficiency of oil production, a method has been considered that first heats the oil layer by applying electricity, and when the oil layer becomes soft, hot water or high-temperature, high-pressure steam is injected to continue heating and extract the fluidized oil. There is. In order to efficiently heat the oil layer, the electrode device used in this method must be electrically insulated to avoid current leakage outside the oil layer as much as possible. It is necessary that the pressure of the injected hot water or high-temperature, high-pressure steam does not cause damage, and furthermore, it is necessary that the hot water or high-temperature, high-pressure steam does not leak.

In order to explain this electrode device more specifically, an example in which oil is produced from oil sand will be described below.

Oil sands, also known as tar sands, have been found in Canada, Venezuela, and the United States. Oil in oil sands coexists with salt water on the surface of the sand and in the gaps between the sands.
It has extremely high viscosity and has no fluidity in its natural state. The oil sand layer is mostly 200 to 500 meters underground, with some parts exposed in canyons and riverbanks.
Excavating the oil sands and separating the oil on the ground is limited in terms of economics and environmental protection, so it is necessary to extract only the oil from underground. . Additionally, since oil production from shallow underground layers is at risk of cave-ins, it is recommended to extract oil from layers less than 300 meters underground.

The biggest problem with an electrode device that heats an oil sand layer by applying electricity is that the electrical resistance of the oil sand layer is higher than that of the stratum above the oil sand layer. It is difficult to express it uniformly because it varies depending on the location and conditions, but the average value is 100 Ω-m for the oil sand layer and 10 Ω-m for the upper stratum. For this reason, if two electrode devices are installed in which electrodes are connected to a casing made of copper pipes and the electrodes are buried in the oil sand layer and then 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 schematically shown, the electrode devices are arranged as shown in FIG. In Fig. 1, 1 and 11 are casings made of steel pipes, 2 and 12 are insulators bonded to the casings 1 and 11, 3 and 13 are electrodes bonded to the insulators 2 and 12, and 4 and 14 are insulators bonded to the casings 1 and 11. The cables that send current to the electrodes 3 and 13 are collectively called an electrode device. 5 is a power supply device, 6 is an oil sand layer, 7 is a current between electrodes 3 and 13, 8 is on the ground, 9
10 is the oil sand upper layer, and 10 is the oil sand lower layer. Electrodes 3 and 13 buried in the oil sand layer 6
When a voltage is applied 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, generating Joule heat and heating the oil sand layer 6. 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 since the insulators 2 and 12 are interposed between the casings 1 and 11 and the electrodes 3 and 13, the leakage of the current 7 is kept small. It will be done. When the oil sand layer 6 warms up, the electricity is turned off, and hot water or high-temperature steam is forced into the upper part of the casing 1 of the electrode device, passing through the oil sand layer 6.
The oil flows out from the casing 11 of the other electrode device 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 pores.

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

Regarding these matters regarding electric heating, see, for example, U.S. Patent No. 3946809 and Canadian Patent No.
It is stated in No. 1022062.

The electrode device does not break when buried, and has sufficient strength to withstand earth pressure when it is first buried.When electricity is applied, the temperature rises, which is particularly noticeable near the electrode due to the high current density, but does not cause deformation or destruction, and the internal They are required to withstand the static pressure of the liquid that fills them, 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,
If the specific gravity of the liquid filled inside is 1, it is 50Kg/
The temperature of water vapor with a pressure of 50 Kg/ ^{cm 2 reaches} 265°C.

Since the upper parts of the insulators 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 insulators 2 and 12, and the conditions are 250℃~ Since the temperature is 300℃, characteristics that meet this requirement are required.
Next, these insulators 2 and 12 have electrodes 3 and 13 suspended from their lower ends, and the upper ends are connected to the casings 2 and 12, and are installed several hundred meters underground, so they are connected to the hole wall during the installation process. In reality, contact or collision is an unavoidable condition. Since the overall weight is heavy, even a slight contact causes a large mechanical shock to the insulators 2 and 12. Characteristics that can withstand this impact and prevent damage are also required.

Much research has been conducted to obtain insulators 2 and 12 that satisfy the above-mentioned required characteristics and have practical value. The first method we investigated was to connect a flanged tubular product made of metal with a coating made of an organic resin with excellent heat resistance, such as Teflon, over the entire surface. Although it is possible to obtain a product that maintains complete characteristics regarding suspension load strength and mechanical impact strength,
The coating structure of the flange part and the connection method that maintains the insulation are extremely difficult, and although it is possible to somehow obtain a product that maintains the necessary insulation properties under room temperature conditions, it is difficult to find a connection method that maintains the required insulation properties under conditions of actual use, which is between room temperature and 250℃. When repeated, the inherent difference in thermal expansion/contraction rate causes peeling, especially at the flange portion, which leads to the breakdown of insulation, which is an unavoidable fatal defect, making it unusable.

The next material to be considered was porcelain. In the first place, the insulators 2 and 12 are required to have water (oil) tight properties as described above, so it is necessary to consider the connection method between the casings 1 and 11, the electrodes 3 and 13, and the insulators. . A commonly considered method is to shrink-fit a metal tube onto the outer periphery of a porcelain tube, and connect the metal tube by a conventional method such as welding or screwing. With this method, water (oil) tightness can be ensured at room temperature, but as the temperature rises, the shrink fit strength decreases, leading to a decrease in suspension strength, and damage due to stress generated at the tip of the shrink fit. Defects such as these begin to appear. In order to eliminate this defect, there is a method of providing flanges at both ends of the porcelain tube, interposing packing material on the contact surface, and tightening the flanges with metal.However, in this case, sufficient characteristics can be secured at room temperature, but when the temperature rises, the porcelain tube Due to the difference in the coefficient of thermal expansion with the quality, an unavoidable defect appears that the water (oil) tightness is reduced. Other porcelain materials inherently have poor mechanical impact strength, and as mentioned above, there is an inherent condition that there is an extremely high possibility that they will be damaged by mechanical impact that occurs under unexpected conditions during the installation process. The unavoidable drawback is that there is a large risk element when used in

The present inventors have succeeded in obtaining a useful electrode device for electric heating in which the above defects have been eliminated. Next, the contents will be explained in detail based on one embodiment.

First, for the insulator 2 or 12 constituting the electrode device, an insulating pipe joint 21 shown in FIG. 2a is used. The configuration of this insulated pipe joint 21 will be explained below. This pipe joint 21 is manufactured by machining from a molded product 31 shown in FIG. 2b. For ease of understanding, this molded product 31 will be explained first. This molded product 31 is composed of an inner circumferential metal fitting 32, an outer circumferential metal fitting 33, and an insulator 34. The inner circumferential metal fitting 32 has a support portion 32-2 at the lower end of the cylindrical body 32-1, and a screw 32-2 on the outer periphery of the upper portion thereof.
3 and a convex portion 32-4 having an outer diameter larger than that of the support portion 32-2, and a concave portion 32-5 that holds a gap with the screw 33-4 of the outer peripheral fitting on the upper portion thereof;
It has a structure in which a parallel part 32-6 which is larger and has an outer diameter through which the screw 33-4 can pass, and an auxiliary part 32-7 which has an outer diameter smaller than this parallel part 32-6 are connected and held. The outer circumferential fitting 33 is placed on the cylindrical body 33-1 having the same inner diameter as the inner circumferential fitting 32.
The support part 33- maintains a gap of the same size between the outer peripheral part of the support part 32-2 and the bottom surface of the convex part 32-4.
2, a recess 33-3 that maintains a gap of the same size as the above gap between the screw 32-3 and the small diameter, and the screw 32-3.
3, and has a screw 33-4 that is screwed into the recess 32-5.
The threaded part 33-7 and the parallel part 32-6, in which the interval between the thread diameter and the thread diameter of the screw, are the same as the above-mentioned interval, and the apexes are at the same height. 33-5. The material used is iron. As shown in FIG. 2b, the screws 32-3 of the inner metal fitting 32 are passed through the screws 33-4 of the outer metal fitting 33, and the support portion 32-2 is placed on the cylindrical body 33-1. At this time, maintain an equal gap between each part of both metal fittings.Insulator 34 made of glass or mica plastic is inserted into this gap.
-1, 34-2, and 34-3 are filled to seal and fix both metal fittings. Glass constituting the above insulator;
Mica plastic bodies are made from a mixture of glassy powder and mica flake-like powder.This raw material powder is heated to a temperature where the glassy material becomes soft and can flow under pressure, and then pressure molded in the heated state. It is made by.

This molded product 31 is made by using a special mold (not shown) and heated to a predetermined temperature.The inner circumferential metal fitting 32 and the outer circumferential metal fitting 33 are assembled as shown in FIG. 2b and heated to a predetermined temperature. The raw material powder is heated and inserted into a mold in a heated state, and then a cylindrical preform that can be inserted into the gap between the inner metal fitting 32 and the outer periphery of the mold is created. , heat this to a predetermined temperature, insert it in the heated state, pressurize it in the heated state, press fit into the gap between both metal fittings, and insulators 34-1, 34-
It is constructed by configuring 2,34-3.

The above preform is made by mixing 45W% powder of vitreous Nippon Fellow Co., Ltd. No. C-6 glaze for ironware enamel crushed into 200 meshes and 55W% powder of synthetic gold fluorine mica powder of 60 to 200 meshes. , water approximately 5W%
Using a separate mold (not shown), the required amount is cold-pressed into a specified cylindrical shape, and then dried to remove moisture. This was completed in 2008.

The molded product manufactured as described above is machined into an insulated pipe joint shown in FIG. 2a.
Insulators 34-1 and 34-3 are exposed and constitute external and internal insulation parts. Inner circumferential fitting 32 and outer circumferential fitting 3
3 has pipe screws 35-1, 35- for connecting metal pipes.
2 is threaded to obtain the insulated pipe joint necessary for the present invention.

The characteristics of the insulated pipe joint with this structure will be explained. General mechanical and electrical properties are insulating. The tensile properties of glass and mica plastic bodies are largely controlled by their structure.The properties of glass and mica plastic bodies are determined by the arrangement of the mica powder that constitutes them and the glass properties. First, the arrangement of mica powder will be explained. This mica powder is in the form of flakes, and the ratio of average particle diameter to thickness of the flakes is generally 30 to 50:1. On the other hand, vitreous powder is in the form of fine powder with no directionality. When the above-mentioned mixed powder is heated to a temperature at which the vitreous material becomes soft and flowable, and then is press-molded in the heated state, if the mixed powder has a plate-like shape, the mixed powder will be pressurized with almost no movement. At this time, the mica flakes are arranged parallel to the pressurized surface, making it look like a laminated product. Next, when the mixed powder is molded by pressure so that it flows and is press-fitted into the gap, the parts that are aligned in the flow direction and receive pressure without moving will be aligned parallel to the pressure direction. The direction in which the mica flakes are arranged is indicated by the chain line in b of FIGS. 2 and 4, and the upper insulator 34-4 remaining on the upper part during molding is parallel to the pressurizing surface, but the inner peripheral metal fitting 32 and the outer periphery are parallel to each other. The insulators 34-1 to 34-3 formed in the gaps between the metal fittings 33 are all parallel to the flow direction and arranged parallel to the surface of the metal fittings.

The relationship between the alignment direction of the pickles and mica flakes and their mechanical and electrical properties will be explained. First, regarding mechanical strength, tensile strength is strong in the direction parallel to the alignment and conversely, extremely strong in compression in the direction perpendicular to the alignment, but extremely weak in tension as it causes delamination. Therefore, when the thickness of the molded product reaches approximately 25 mm, in the case of a single molded product, stress occurs on the surface and inside, and as shown in the insulator 34-4 in Figures 2b and 4b, In products that are molded in contact with metal, delamination may occur due to stress caused by the difference in coefficient of thermal expansion. As mentioned above,
Mechanical strength is largely controlled by the arrangement direction.

Next, regarding the relationship with electrical characteristics, the characteristics also vary greatly depending on the arrangement direction. In the direction perpendicular to the alignment direction, a withstand voltage of 15 to 20 kv/mm is maintained, but in the parallel direction, it is largely controlled by the density. It is extremely weak.

Regarding the electrical characteristics of the insulated pipe joint 21, which is a pipe product, as shown in Fig. 2a, the inner peripheral fitting 32 is machined and finished so that the insulators 34-1 and 34-3 are exposed on one side. ing. Since all of the insulators 34-2 existing in the gap between the inner circumferential metal fitting 32 and the outer circumferential metal fitting 33 are arranged parallel to the surface of the metal fitting, the withstand voltage is extremely high and there is no problem as described above.
Next, regarding creeping insulation resistance, insulators 34-1, 34
-3 Since both are arranged parallel to the outer peripheral metal fitting 33, delamination does not occur even when the length becomes long, and the mechanical strength is stable and a long creeping length can be obtained. Next, regarding tensile strength, screw 32
-3 and 33-4 are screwed through, and the mica flakes in the gap between the screws are arranged parallel to the screws, and the tensile load causes them to be compressed, so their strength is extremely high. By changing the structure of the screw and adjusting the facing area, it is possible to obtain a screw having the required characteristics. Next, regarding mechanical impact strength, glass is an insulator, and mica powder, which is a raw material for mica molded bodies, is flaky as mentioned above, so unlike molded products containing simple powder,
Because it has high elasticity, it has far greater thermal and mechanical impact strength than general inorganic insulators, and maintains sufficient strength to withstand unexpected impacts during burial work. Next, regarding strength at high temperatures, heat resistance properties are closely related to the thermal properties of the glass used as raw materials, and the relationship with the transition temperature of the glass is dominant. There is almost no decrease in target strength. In other words, if a glass material with a dislocation temperature higher than 360°C is used, it will maintain perfect heat resistance at 300°C.

The biggest problem with this insulated pipe joint is that it is difficult to make the creepage insulation length extremely long, and the length is approximately 1/1/1 of the outside diameter of the insulators 34-1 and 34-3.
2 is the limit. If the coefficient of thermal expansion below the vitreous transition temperature of the glass or mica plastic body is made equal to the coefficient of thermal expansion of the outer peripheral fitting 33, the above limit will increase and it will be possible to have a dimension that is approximately the same as the outer diameter dimension, but such a large thermal expansion Corrosion resistance properties of glass and mica plastic bodies are extremely reduced and their practical value is poor, so taking this into consideration, the limit is about 1/2 of the outer diameter as described above.

Next, the structure of an embodiment of an electrode device using the above-mentioned insulated pipe joint 21 will be explained with reference to FIG. In the figure, numerals 1 to 4 are the same as those in FIG. Figure 3a shows the basic structure.The insulator 2 is an insulating pipe joint 212.
It is connected by a connecting tube 22 having screws 22-1 at both ends. Insulator 2
The casing 1 and the electrode 3 are both connected to both ends thereof by connection screws 35-1 and 35-2. In the case of this electrode device, the screws used to connect the casing 1 can be used as they are to connect each part, and the connection work can be carried out extremely easily, which is a great advantage. Furthermore, since each part has a communicating hole of the same size, parts necessary for the partition plate and the like can be easily attached. The biggest feature of this insulator 2 is the insulating part 34-1 of the insulating pipe joint 21,
34-3 are all located at the inner peripheral part of the outer peripheral fitting 33. This completely prevents the insulator from coming into contact with the hole wall and damaging it during burying, and the burying work can be carried out with a high degree of reliability.
In this basic configuration diagram, the insulator 2 is made up of two insulating pipe joints 21, but in order to ensure the creeping insulation length, it is sufficient to increase the number and connect them. Further, the use of this insulating pipe joint 21 is not limited to the configuration of the insulator 2, but it can also be used in the middle of the casing 1.

Next, as described above, if a highly concentrated saline solution exists on the outer periphery of the insulator 2 and a particularly high creeping insulation resistance is required, the connection pipe 22 of the insulated pipe joint 21 is By connecting an organic coating material 41 with high heat resistance properties to the insulator 34-1 on the outer periphery of the tube, it is possible to easily ensure the necessary properties. It is an effective method to construct the covering material 41 using materials. In this case, the covering material 41 is not exposed on the outer circumferential surface of the insulating pipe joint 21, so there is no risk of damage due to contact with the hole wall during burying.

FIG. 4a shows another embodiment of the present invention, and the difference from FIG. 2a is that the outer metal fitting 33 at the upper part of the insulator 34-1 is cut away, and the inner metal fitting 32 is left.
This is the point where the upper part of the insulator 34-1 is exposed to the outside.

Furthermore, as shown in FIG. 4b, by providing an insulating coating material 41 on the outer circumferential surface of the connecting pipe 22 of the insulated pipe joint, the creepage insulation distance can be further increased, and the insulation between the casing and the electrode can be further improved. can.

As described above, according to the present invention, the tensile force generated at both ends of the insulated pipe joint becomes a compressive force between the screws of the second tubular member constituting the insulated pipe joint, and compresses the insulator filled between the screws. Since the strength is much higher than the tensile strength, it has various effects such as being able to sufficiently withstand large mechanical impact strength, and being simple in structure and easy to manufacture.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing a state in which an oil sand layer is heated by an electric heating device, Fig. 3a is a sectional view showing an embodiment of the present invention, Fig. 3b
is a sectional view showing another embodiment of the present invention, FIG.
Figures 3 and b are cross-sectional views showing one embodiment of the insulated pipe joint shown in Figure 3 a and b, and a cross-sectional view showing the structure of the molded product, and Figures 4 a and b are shown in Figure 3. FIG. 2 is a cross-sectional view showing another example of the insulated pipe joint, and a cross-sectional view showing the structure of the molded product. In the figure, 1 is a casing, 2 and 22 are insulators, 3 is an electrode, 4 is a cable, and 21 is an insulated pipe joint. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first tubular member having a threaded portion at one end;
a second tubular member having at one end a threaded portion that is threaded into the thread of the first tubular member; An insulating pipe joint comprising an insulator filled in a gap formed by passing through a threaded part to seal and fix the first and second tubular members and insulate between the first and second members, an insulating pipe joint made of hydrocarbon. a metallic tubular casing buried in a stratum covering above the hydrocarbon-based underground resources; an electrode buried in the hydrocarbon-based underground resources for flowing a current to the hydrocarbon-based underground resources; An electrode device for electric heating of hydrocarbon-based underground resources, comprising the above-mentioned electrode fixed to one side and the above-mentioned metal casing fixed to the other side. 2. An electrode device for electrically heating hydrocarbon-based underground resources according to claim 1, which has a plurality of insulating pipe joints, and the plurality of pipe joints are connected by a connecting pipe. . 3. The electrode device for electrically heating hydrocarbon-based underground resources according to claim 1, wherein the insulator of the insulating joint is a glass or mica plastic body made of glass and mica powder.