JPS6226396B2 - - 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 underground in order to increase the fluidity of hydrocarbons that exist underground, with high viscosity and low fluidity, when produced from wells. It is.

"Hydrocarbons" here refer to petroleum or oil, bitumen contained in oil sands (also called tar sands),
This refers to the kerogen contained in oil shells, and for the sake of brevity, 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 it can be self-injected by the pressure of the gas coexisting in the oil layer, pumped up, or injected with liquid such as salt water from one well. It is possible to produce oil by draining the well from the other well. However, if the fluidity of underground oil is low, production cannot be achieved unless a means is purchased to allow the oil to flow. 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 the oil layer include 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. 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 and increase the fluidity of the oil, while at the same time allowing the fluidized oil to flow to the surface. If it exists, there is a risk that it 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.

In the energization heating method, multiple wells are dug in the oil layer, electrodes are installed in these wells, and a potential difference is applied between each electrode to heat the oil layer using the conductivity of the oil layer. However, it has the advantage of being easy to heat the entire area. 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, and must be electrically insulated to prevent current leakage outside the oil layer. It is necessary that the pressure of the heated 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 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 is mostly underground, at a depth of 200 to 500 m and approximately 50 m thick. The oil sand is excavated and the oil is separated above ground. Because there are restrictions on economics and environmental protection, it is necessary to extract only the oil from underground. In addition, oil production from shallow underground layers is at risk of cave-ins.
It is said that it is desirable to collect from layers below 300m underground.

To schematically show the case where an oil sand layer is heated by electricity, an electrode device is arranged as shown in FIG. In FIG. 1, 1 and 11 are main pipes made of steel pipes, 2 and 12 are tubular insulators joined to the main pipes 1 and 11, 3 and 13 are joined to the insulating pipes 2 and 12, and openings 3a, The electrodes 13a and 4 and 14 are cables that send current to the electrodes 3 and 13, and these are collectively referred to as an electrode device. 5 is a power supply device, 6 is an oil sand layer, 7 is a current between the electrodes 3 and 13, 8 is the ground, 9 is an oil sand upper layer, and 10 is an oil sand lower layer. Cables 4 and 1 are connected to the electrodes 3 and 13 buried in the oil sand layer 6 from the power supply device 5 on the ground.
When a voltage is applied through the oil sand layer 6, a current 7 flows depending on the electrical resistance in the oil sand layer 6, generating Joule loss 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 the main pipes 1 and 1
Since the insulating tubes 2 and 12 are interposed between the electrodes 1 and the electrodes 3 and 13, 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 top of the main pipe 1 on one side of the electrode device, passing through the oil sand layer 6 and passing through the main pipe 11 on the other electrode device. It flows out with more oil. In order to improve the outflow of hot water or high-temperature and high-pressure steam, the electrodes 3 and 13 are provided with pores 3a,
13a is open.

Electrode devices have a temperature rise when energized, and this tendency is particularly large for electrode 1 due to the high current density.
The adjacent insulator 2 also becomes very hot. Furthermore, when high-temperature, high-pressure steam is injected, for example, if it is buried 500 meters underground, if the specific gravity of the liquid filled inside is 1, a pressure of 50 Kg/cm ² will be applied, and 50 Kg/cm ²
The temperature of water vapor with a pressure of 265℃ reaches.
For these conditions, among the components of the electrode device,
Since the main conduit 1, electrode 3, and cable 4 are made of metal materials, there is almost no problem, but the insulator 2
Since they are made of non-metallic materials, their range of selection is limited.

It has corrosion resistance properties against hot water at a temperature close to 300°C, especially since salt is present in the real world. Moreover, since the electrode 3 is suspended below the insulator 2, a suspension load is always applied. Due to the above conditions, no organic material has been found that retains the characteristics, and as a result, the product is limited to porcelain tubular products. In the case of porcelain tubes, the biggest problems are that the required length, for example, 3 to 7 m, cannot be molded as a single piece, and that the mechanical impact strength is low.

The former problem can be bonded using metal materials, but the latter problem is extremely difficult to solve.

Mechanical impact strength becomes a particular problem in the process of burying the main pipe 1 in a vertical hole excavated approximately 500 meters underground with the electrode 3 at the bottom and the insulator 2 in between. Due to the cost of vertical hole drilling, the diameter of the hole is limited, and holes with a large inner diameter that can be afforded are generally not drilled. Therefore, in this embedding process, the electrode 3
The insulator 2 may come into contact with or collide with the hole wall, and it is practically impossible to completely avoid this phenomenon.

A method for dealing with the above problem in the prior art will be explained with reference to FIG.

In the figure, 1, 2, 3, 3a, 4, 6 and 9 are the same as in FIG. Reference numeral 21 denotes a hole wall made of cement and formed inside the vertical hole. Insulation tube 2
Since a monolithic porcelain tube of the required length cannot be obtained, the porcelain tube 2-1 is constructed by connecting a plurality of porcelain tubes 2-1.
Although three consecutive wires are shown in FIG. 2, in reality, the required number of wires are connected. A connector 22 is made of a metal material and connects the porcelain tubes 2-1 to each other and the porcelain tubes 2-1 to the main pipe 1 and the electrode 3, respectively. There are several joining methods, such as shrink fitting and tightening using a packing material (not shown), but they are joined while maintaining watertightness. A shock absorber 23 is installed around the outer periphery of the insulator 2, and serves to prevent the electrode 3 and the insulator 2 from directly contacting or colliding with the hole wall 21 and receiving a large mechanical shock during the embedding process. In this case, the connector 22
Since it is constructed using the fulcrum as a fulcrum, it is impossible to use metal materials due to insulation, and organic materials, which are insulators, are used exclusively. It had a fatal flaw in that it had poor mechanical strength and, in particular, almost no elasticity, so it could be damaged by contact, making it difficult to function as a shock absorber.

The present invention has been made in order to eliminate the above-mentioned defects, exhibit a sufficient buffering effect, and provide an electrode device that can be safely buried underground.

The present invention will be explained with reference to FIG. In Figure 3, 1, 2, 3, 3a, 4, 6, 9, and 22
is the same as in Figure 2.

The insulating tube 2-1 constituting the insulator is one that holds a plurality of annular support rings 2-2 on its outer periphery. The shock absorber 23 is installed using the support ring 2-2 as a fulcrum. In this case, insulation is completely ensured, so it is possible to use metal materials for the buffer 23.
Appropriate materials can be selected and used with elastic modulus taken into consideration, and the buffering effect can be fully demonstrated, making it possible to safely bury the electrode device underground, and the defects of conventional products have been completely eliminated. In addition, although FIG. 3 shows a state in which the buffer 23 is installed with the support ring 2-2 of the adjacent porcelain tube 2-1 as a fulcrum, It is also possible to install the shock absorbers 23 at the same time, and by mixing shock absorbers 23 with different elastic forces, it is possible to make the effect even more remarkable.

In the case of the embodiment shown in FIG.
-2 is provided multiple times, but even if there is only one,
This can be implemented as long as the width of the support ring is a creepage distance that can maintain insulation between the shock absorbers 23, 23.

Note that the operations for heating the oil sand layer 6 and taking out the oil are the same as in the conventional apparatus.

In the present invention, as is clear from the above invention, a plurality of support rings 2-2 are provided on the porcelain tube 2-1 constituting the insulator 2, and the shock absorber 23 is
When installing a shock absorber 23, since insulation is completely ensured, it is possible to use a metal material with high elasticity and mechanical strength for the shock absorber 23, which prevents damage to the insulator 2 during the process of burying it underground. A greatly improved electrode device that can be installed safely has been obtained, and its effects are extremely significant.

[Brief explanation of the drawing]

Fig. 1 is a sectional view schematically showing a state in which an oil sand layer is heated by an electric heating electrode device, Fig. 2 is a sectional view showing the main part of the prior art electrode device, and Fig. 3 is a sectional view of the present invention. FIG. 2 is a cross-sectional view showing the main parts of the electrode device. In the figure, 1 and 11 are main pipes, 2 and 12 are insulated pipes,
3, 13 are electrodes, 3a, 13a are openings, 4, 1
4 is the cable, 5 is the power supply, 6 is the oil sand layer,
7 is electric current, 8 is above ground, 9 is upper oil sand layer, 1
0 is the lower layer of oil sand, 2-1 is porcelain insulation pipe,
2-2 is a support ring, 22 is a connector, and 23 is a buffer. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In an electrode device in which a plurality of porcelain insulating tubes are arranged between a main conduit and a tubular electrode, the opposing ends of each tube are connected by a joining fitting, and the electrode device is inserted into an excavated hole to apply a voltage to the electrode, Each of the plurality of insulating tubes has a support ring on its outer periphery, and is supported by the support ring and is insulated from each other, and is provided with a metal shock absorber that protects the insulating tube from the hole wall of the excavation hole. An electrode device for electrically heating hydrocarbon-based underground resources.