JPS5816439B2 - Electrode device for electrical heating of hydrocarbon underground resources - 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, it relates to an electrode device used to heat and energize the underground to increase the fluidity of hydrocarbons that exist underground, with high viscosity and low fluidity, when produced from wells. It is something.

"Hydrocarbons" here refer to betroleum or oil, bitumen contained in oil sands (also called tar sands), and kerogen contained in oil shells. Let's call hydrogen oil.

Furthermore, "production" refers to the extraction of fluid oil from an oil well, such as artesian injection, pumping, and fluid transfer.

If the oil in the ground has fluidity, a well is dug to reach the oil layer from the surface, and the oil is pumped up by a gas field that coexists with the oil layer, pumped up, or liquid such as salt water is pumped from one well. It is possible to produce oil by such methods as draining water from other wells.

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, and at a temperature suitable for fluidization (this varies depending on the individual properties of the oil, but it becomes necessary to heat the underground oil layer). .

As methods for heating the oil layer, injection of hot water, injection of high-temperature, high-pressure steam, underground electrification, underground combustion method (igniting the underground oil layer and blowing air to burn it), and the use of explosives have been proposed. However, 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 it is possible to flow the fluidized oil to the surface due to cracks, holes, etc. If there is, there is a risk that if the oil layer is hard and dense, it will not spread to the whole area.On the other hand, if the oil layer is hard and dense, the hot water or steam will not diffuse and the temperature will be difficult to rise. The method uses the electrical conductivity of the oil layer to heat the oil layer by installing electrodes in these wells and applying a potential difference between each electrode. It has the advantage of being easy to heat.

However, other means are required to remove the fluidized oil.

Therefore, as a method to increase the efficiency of oil production, the oil layer is first heated by energization, and when the oil layer softens, hot water or high-temperature, high-pressure steam is injected to continue heating and the fluidized oil is extracted. .

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 force of the injected hot water or high-temperature, high-pressure steam does not destroy it, 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 cool sands, have been found in Canada, Venezuela, and the United States.

Oil in oil sand coexists with salt water on the surface of the sand and in the gaps between the sand, but it has extremely high viscosity and has no fluidity in its natural state.

The oil sand layer is partially exposed in canyons, riverbanks, etc., but most of it exists at a depth of 200 to 500 meters underground and several tens of meters thick.The oil sand layer is excavated and separated on the ground. Because there are restrictions on economics and environmental protection, it is necessary to extract only the oil from underground.

Furthermore, since oil production from shallow underground layers is at risk of cave-ins, it is said that it is desirable 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 differs depending on the location and conditions, but if we show the average value, the oil sand layer strength per month is 00
Ω-m, and the upper stratum is 10 Ω-m.

For this reason, if two electrode devices are installed in which electrodes are connected to a casing made of steel 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 cover layer on the surface of the casing in the stratum, 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 viewed horizontally, 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 joined to the casings 1 and 11,
3, 13 are electrodes bonded to insulators 2, 12, 4, 14
is a cable that sends current to the electrode 3゜13, and this is collectively called an electrode device.

Reference numeral 5 indicates a power supply device 6 in the oil sand layer, 7 indicates a current between the electrodes 3 and 13, 8 indicates the ground, 9 indicates an upper layer of oil sand, and 10 indicates a lower layer of oil sand.

When electric power is applied to the electrodes 3 and 13 buried in the oil sand layer 6 from the power supply device 5 on the ground through the cables 4 and 14, a current 7 flows according to the electrical resistance in the oil sand layer 6, generating Joule loss. Then, the oil sand layer 6 is heated.

At this time, part of the current 7 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, high-pressure steam is injected from the upper part of the casing 1 of one of the electrode devices. Spills out with 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, saline solution is normally fed into the electrode device through a pipe (not shown), and the saline solution and the casings 1 and 1
A partition plate (not shown) is provided above the electrode 3.13, and the upper part of the partition plate is filled with an insulating liquid.

Regarding these matters regarding electric heating, for example, U.S. Patent No. 3,946.809 and Canadian Patent No. 1,0
No. 22,062.

The electrode device does not break when buried, has sufficient strength to withstand Ueda when it is first buried, and does not deform or break, although it is particularly noticeable because the temperature rises when electricity is applied and the current density is high near the electrode.
It is required to withstand the liquid that fills the 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, if the specific gravity of the liquid filled inside is 1, it will be 50ky/cff.
The temperature of the steam with a pressure of 50 ky/i reaches 265°C.

Note that the upper part of the insulators 2, 12 is connected to the casing 111, and the lower part is connected to the electrodes 3, 13, so the insulators 2, 12
A suspension load is always applied to the material, and the condition is a high temperature of 250° C. to 300° C., so properties that satisfy this 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 the hole wall is removed during the installation process. In reality, contact or collision with other vehicles is an unavoidable condition.

Since the overall weight is heavy, even a slight contact causes a severe mechanical shock to the insulators 2 and 12.

Characteristics that can withstand this impact and prevent damage are also required.

Insulators that meet the above requirements and have practical value 2.12
A lot of research has been done to obtain this.

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 perfect characteristics in terms of suspension load strength and mechanical impact strength, it is extremely difficult to create a connection method that maintains the coating structure and insulation of the flange part.
Under room temperature conditions, it is possible to somehow obtain a product that maintains the required insulation properties, but when exposed to repeated temperatures between room temperature and 250°C, which is the actual usage condition, the flange part in particular becomes weaker due to the inherent difference in thermal expansion and contraction coefficients. An unavoidable fatal defect occurs in which a peeling phenomenon occurs and the insulation is destroyed, making it unusable.

The next material to be considered was porcelain.

In the first place, these insulators 2 and 12 contain water (oil) as mentioned above.
Since sound characteristics are required, the casing is 1°1.
1. It is necessary to consider the connection method between 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.

In this method, water (oil) sound characteristics can be ensured at room temperature, but as the temperature rises, the shrink-fitting strength decreases, leading to a decrease in suspension strength, and damage due to stress generated at the tip of the shrink-fitting. Defects such as these begin to appear.

In order to eliminate this defect, there is a method of installing flanges at both ends of the porcelain tube, interposing packing material on the contact surface, and tightening the flanges with metal.In this case, sufficient characteristics can be secured at room temperature, but when the temperature rises, Due to the difference in thermal expansion coefficient with porcelain, water (oil)
The inevitable defect that the sound characteristics deteriorate begins to appear.

In addition, since magnetic lipids inherently have poor mechanical impact strength, 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, as mentioned above. 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. 2 is used.

The configuration of this insulated pipe joint 21 will be explained below.

Reference numeral 22 in the drawing denotes a first tubular member, which has a flange 24 surrounding the entire circumference at one end of a steel pipe 23 having the same inner and outer diameter dimensions as the casing 1.

Reference numeral 25 denotes a second tubular member, which is a ring-shaped cover having an inner diameter larger than the outer diameter of the upper Q-shaped steel pipe 23 and smaller than the outer diameter of the flange 24. The part 27 has a lid part 29 having a female screw 28 at the lower part, a steel pipe 30 having the same inner and outer diameters as the casing 1 at one end, a cylindrical cavity part 31 thicker than the inner diameter of the steel pipe 30 at the upper part, and a male part on the outer periphery. The base portion 33 has a screw 32.

That is, the second tubular member 25 has a bag portion 34 at one end that accommodates the flange portion 24 of the first tubular member 22 with a gap maintained therebetween.

The first tubular member 2 is attached to the lid portion 29 of the second tubular member 25.
2, the base 33 is screwed onto the lid 29 to form an integral structure, and held so that a gap is maintained between the flange 24 of the first tubular member 22 and the bag 34 of the second tubular member 25. Then, an insulator 35 is interposed in this gap to seal and fix the first and second tubular members, and integrally with this insulator 36, the outer insulator 35 of the first tubular member 22 is inserted into the second tubular member. An inner peripheral insulator 37 having an inner diameter larger than that of the steel pipe 30 is formed in the cavity 31 of the member 25.

The insulators 35, 36, and 37 are made of glass-mica plastic bodies.

A glass mica molded body is produced by using a mixed powder of vitreous powder and mica powder as a raw material, heating the raw material powder to a temperature at which the vitreous material can flow under pressure, and then molding in the heated state.

This insulating pipe joint 21 is made by using a special mold (not shown) and heating the first tubular member 22 and the second tubular member to a predetermined temperature.
The tubular member 25 of the first tubular member 22 is heated to a predetermined temperature as shown in FIG. A preform is molded into a cylindrical shape that can be inserted into the gap of the mold, heated to a predetermined temperature, inserted in the heated state, and immediately pressurized to form the outer insulator 36. Insulator 35
, the inner peripheral insulator 37 is constructed by human intervention.

The above-mentioned preform is made of vitreous material containing 45W% powder of 42312 ironware enamel glaze manufactured by Nippon Ferro Co., Ltd., crushed into 200 mesh, and 60~20% synthetic total fluorine mica powder.
A raw material was prepared by mixing 55W% of a 0-mesh product and adding 5W% of water to make it wet. 1500g was weighed out and made into a cylinder by cold pressure molding using another mold (not shown). A shaped article was created and kept in a dryer at 120° C. for 2 hours to remove moisture and complete the creation.

Although the lid portion 29 and the base portion 33 of the second tubular member 25 are connected by screws, they may be connected by welding.

Further, the covering part 27 of the second tubular member 25 is divided into four equal parts, two of them are cut out, and the first tubular member 22 is passed through the cut parts.
The flange portion 24 is arranged so that the flange portion 24 is stored in the bag portion 34.
The bag portion 34 of the second tubular member 25 is cut out. The collar portion 24 of the first tubular member 22 may be housed.

The details of the insulated pipe joint and its manufacturing method are described in Patent No. 55-51152 filed on the same day by the same applicant.

- In the insulated pipe joint with this structure, the tensile force generated at both ends becomes a compressive force between the bag portion 34 and the collar portion 24.

Generally, the wire strength of this type of insulator is much higher than the tensile strength, and in the case of this structure, the load per unit area can be adjusted arbitrarily by increasing the facing area where compressive force is applied. Therefore, there are almost no concerns regarding mechanical strength.

Note that at high temperatures, in this case about 300° C., the heat resistance properties are closely related to the thermal properties of the glass used for the raw material powder.

In particular, the relationship with dislocation temperature is remarkable.

When using a material with a dislocation temperature of 550°C to 600°C 3
There is almost no decrease in mechanical strength at 00°C.

Next, regarding mechanical impact properties, mica powder, which is the raw material for glass mica molded bodies that are insulators, has a perfect flake shape, and the ratio of the average area diameter and thickness of each flake is generally 30 to 30.
A ratio of 50:1 is maintained.

Therefore, the glass mica plastic body has a completely laminated shape, and unlike a molded product containing mere powder, it has high elasticity.

For the above reasons, it has far greater thermal and mechanical impact strength than general inorganic insulators, and maintains sufficient strength to withstand unexpected impacts during burial work.

The biggest problem with this insulated pipe joint is that it is difficult to make the creepage insulation length extremely long;
The limit is about the same size as the diameter of.

The reason for this is that while the steel pipe 23, which is a metal, has linear thermal expansion characteristics, the glass-mica plastic body, like glass, has a transition temperature and bends near the transition temperature. When the temperature rises and falls repeatedly,
There is a risk of cracking.

Now, the structure of an embodiment of an electrode device using the above-mentioned insulating pipe joint 21 will be explained with reference to FIG.

In the figure, numerals 1 to 4 are the same as those in FIG.

FIG. 3a (right half) shows the basic configuration. The insulator 2 is composed of 212 insulating pipe joints, and the casing 1 and the electrode 3 are connected to both ends.

Each connection can be easily made by conventional metal joining methods such as welding and screws.

In the case of this electrode device, since each part has a communicating hole with the same inner diameter, necessary parts such as the aforementioned partition plate can be easily attached.

In addition, in this basic configuration diagram, there are 212 insulating pipe fittings and 2 insulators.
However, in order to ensure the creepage insulation length, it is better 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 mentioned above, if there is a highly concentrated saline solution on the outer periphery of the insulator 2 and a particularly high creeping insulation resistance is required, the insulated pipe joint 21 is connected as shown in FIG. 3b (left half). By configuring the organic coating material 41 with high heat resistance properties on the outer periphery, it is possible to easily ensure the necessary properties such as Q.
For example, it is an effective method to construct the covering material 41 using a shrinkable Teflon tube.

As explained above, the present invention uses a special insulating pipe joint to connect the casing and the electrode.

The tensile force generated at both ends of the insulated pipe joint is equal to the compressive force O between the bag portion and the collar portion.

Since the compressive strength of an insulator is much higher than its tensile strength, the electrode device of the present invention has high mechanical strength and is resistant to pressure and mechanical impact under severe conditions related to underground resource recovery. It can withstand enough.

In addition, if an insulator is provided on the inner and outer circular surfaces of the tubular member of an insulated pipe joint, or if the outer circumferential surface of the insulated pipe joint itself is covered with an insulator, the creepage insulation distance becomes longer and the insulation between the casing and the electrode increases. can be made even better.

Furthermore, if a glass mica plastic body is used as the insulator of the insulated pipe joint, an electrode device that can sufficiently withstand high temperatures can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the state in which an oil sand layer is heated by an electric heating electrode device, and Fig. 2 is a longitudinal cross-sectional view showing the structure of an example of an insulated pipe joint used for insulation constituting the electrode device. 3 is a longitudinal cross-sectional view showing an embodiment of an electrode device constructed from an insulated pipe joint and using differential insulation; FIG. 3a (right half) shows its basic configuration; and FIG. 3b ( The left half) is a diagram showing a state in which the outer peripheral surface of the insulating pipe joint is covered with an insulating material. In the figure, 1 and 11 are casings, 2 and 12 are insulators, 3,
13 is an electrode, 4 and 14 are cables, 5 is a power source, 6 is an oil sand layer, 7 is a current, 8 is above ground, 9 is an upper layer of oil sand, 10 is a lower layer of oil sand, 21 is an insulated pipe joint, 23
24 is a flange, 25 is a second tubular member, 34 is a bag, and 35, 36, 37, and 41 are insulators. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. (a) A metal tubular casing buried underground, (
(b) An electrode buried in an underground hydrocarbon-based underground resource, which allows current to flow through the underground resource, (c) A first electrode having a flange at one end.
a second tubular member having at one end a bag portion that accommodates the flange portion of the first tubular member with a gap therebetween; The second tubular member is sealed and fixed, and the insulator is provided to electrically insulate between the first and second tubular members, and connects the casing and the electrode and is electrically insulated. An electrode device for electric heating of hydrocarbon-based underground resources, comprising an insulated pipe joint for electrically heating hydrocarbon-based underground resources, and a cable connected to the two electrodes for supplying current. 2. The electrode device for electrically heating hydrocarbon-based underground resources according to claim 1, wherein a plurality of insulating pipe joints are connected. 3. The insulator of the insulated pipe joint includes an insulator interposed in the gap between the collar and the bag, and an insulator provided on the inner and outer circumferential surfaces of the tubular member in continuation with this insulator. An electrode device for electrically heating hydrocarbon-based underground resources according to item 1 or 2. 4. The electrode device for electrical heating of hydrocarbon-based underground resources according to any one of claims 1 to 3, wherein the insulator of the insulating pipe joint is made of glass and mica powder and is a plastic body of las mica. . 5. An electrode device for electrically heating hydrocarbon-based underground resources according to claims 1 to 4, wherein the outer peripheral surface of the insulated pipe joint is coated with an insulator. 6. The electrode device for electrically heating hydrocarbon-based underground resources according to claim 5, wherein the outer peripheral surface of the insulating pipe joint is coated with Teflon.