JPS59145897A - Production of electrode support conduit for electrical heating of underground hydrocarbon resources - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an electrode support conduit for electric heating of hydrocarbon underground resources, and more specifically,
This invention relates to a method for manufacturing an electrode support conduit, which is used when extracting underground hydrocarbon resources by electric heating, and has an electrically insulating coating on the outside and a corrosion-resistant protective layer on the inside.

Here, hydrocarbon underground resources refer to bitumen contained in oil sands or tar sands.
), and is hereafter typically referred to as oil sand.

In recent years, as the price of petroleum resources has soared, efforts are being made in earnest to extract oil from underground oil sand layers in countries such as Canada and Venezuela. This oil sand layer usually exists several hundred meters underground as a layer with a thickness of about Sθ meters, but because this oil sand has a high viscosity, it cannot be extracted by pumping it up at room temperature.

Therefore, methods of heating the oil sand by some means to lower its viscosity and extracting the oil content have not been adopted.

One method is to increase the temperature of the oil by injecting heated steam into the oil sand layer. However, this method has the problem of low efficiency and therefore high cost.

As a more productive method for kneading, a pair of conduits made of steel or stainless steel tubes with electrodes supported at their lower ends are connected, the electrodes are located in the oil sand layer, and the electrodes are located in the oil sand layer.
Buried underground at intervals of c30-20θ meters,
An AC voltage of several hundred to several thousand volts is applied between both electrodes, and the Joule heat generated by the current flowing through the oil sand layer raises the temperature of the oil sand layer, lowering the viscosity of the oil and extracting oil. It was suggested that.

In this latter oil extraction method, the resistivity of the oil sand layer is several times higher than that of the upper stratum, and if a voltage is applied over the entire length of the conduit buried underground, an unnecessary large current will flow, resulting in economical power consumption. Due to its nature, a conduit with an insulated surface is required so that current can flow only through the oil sand layer.

On the other hand, when the viscosity of the oil sand layer decreases due to energization of the electrode section, there is a method of injecting high-pressure steam to collect oil sand into one conduit and collecting the oil sand through the other conduit. However, it is necessary to apply a protective layer to the inner surface of the conduit to prevent corrosion due to water vapor and oil sand. Furthermore, K injects salt water into the oil sand layer through a conduit in order to reduce the electrical resistance of the oil sand layer and promote the generation of Joule heat.
It is also necessary to provide the inner surface of the conduit with corrosion resistance against this saline solution W.

The characteristics that must be possessed by the corrosion-resistant protective layer provided on the inner surface of such a conduit are summarized.

(δ,) Must be able to withstand temperatures of approximately 300°C that can reduce the viscosity of the oil sand layer below a certain level during electrical heating.

(b) About injected into the conduit during oil sand extraction,
? Resistant to corrosion by water vapor at 00°C and oil sands extracted.

(c) Scales that can withstand corrosion from salt water.

becomes.

[,Therefore, the purpose of the present invention is to achieve the above (a), (
b).

It is an object of the present invention to provide a method for manufacturing an electrode support conduit for electric heating of hydrocarbon underground resources, which forms a corrosion-resistant protective layer on the inner surface of the metal conduit, which has all of the characteristics of (c).

Another object of the present invention is to arrange a discharge electrode made of a metal core wire to which a negative electrode voltage is applied inside a metal conduit, use the metal conduit as a positive electrode, and statically apply powder with excellent corrosion resistance to the inner surface of the metal conduit. An object of the present invention is to provide a method for manufacturing an electrode support conduit coated with electrolytic powder.

A further object of the present invention is to provide a method for manufacturing a vertical electrode support conduit that forms a uniform corrosion-resistant protective layer on the inner surface of a long metal conduit or a small diameter metal conduit.

This invention will be explained in detail below.

First, the powder for electrostatic powder coating used in this invention is polyetheretherketone resin, and furthermore, this polyetheretherketone resin is combined with short silica glass fibers, quartz powder, or alumina powder that has good hot water resistance. Examples include powders mixed with As the polyetheretherketone resin, aromatic polyetheretherketones represented by the chemical structural formula below and developed by Imperial Chemical Industries Ltd. in the UK are suitable.

Next, as the negative discharge electrode placed inside the metal conduit, a metal core wire with the smallest possible diameter is used, and by forming an unequal electric field inside the metal conduit, a corona discharge that applies a charge of 1M to the powder is generated. It can be made easier to occur. At this time, if the pressure inside the metal conduit is reduced, corona discharge is more likely to occur. Due to this corona discharge, the gas molecules in the metal conduit are ionized, and in a state where positive ions and negative ions are not formed, when powder is flowed through the metal conduit at an appropriate flow rate, the negative ions formed near the discharge electrode are The powder is negatively charged by the corona and adheres to the inner surface of the metal conduit, which is at a positive potential with respect to the discharge electrode.

If the metal conduit having the powder adhered to its inner surface is heat-treated in a heating furnace, and the powder is adhered to the inner surface of the metal conduit by the internal method of the metal conduit, post-treatment using a heating furnace becomes unnecessary. In this case, the insulation resistance of the powder adhering to the inner surface of the metal conduit is reduced because the metal conduit is at a high temperature. Therefore, this powder tends to lose charge in the powder accumulation layer inside the metal conduit, and reverse ionization from the inner surface of the metal conductor (positive electrode) to the discharge electrode side, that is, positive corona, is less likely to occur, causing the powder to accumulate. The layer thickness can be increased. The above-mentioned reverse ionization causes the volume resistivity of the deposited layer of powder to be approximately /θ″
It can be prevented if it is less than Ω・σ.

Further, instead of raising the temperature of the metal conduit, this back ionization can also be prevented by maintaining the inside of the metal conduit at an appropriate humidity.

The above has described the case where the discharge electrode made of a metal core wire is used as the negative electrode, but since the way the powder is charged differs depending on the type of powder, it may be preferable to use the discharge electrode as the positive electrode.

A more specific embodiment based on the method described above will be explained with reference to FIG. Here, a polyether ether ketone resin having a particle size of 10 μm to 100 μm is used as the powder. First, the metal conduit on which the corrosion-resistant protective layer 3 is to be formed on one inner surface is heated to θθ° C. by an induction heating coil λ placed around the metal conduit. On the axis of the metal conduit, a discharge electrode made of a metal core wire is supported and arranged by a flange S made of an insulator. keep. In this state, polyetheretherketone resin powder is flowed into the metal conduit l through the inlet. This powder continuously flows through the metal conduit at an appropriate flow rate and flows out of the metal conduit 7 from the discharge rotor. Nitrogen was used instead of air as the carrier gas for introducing the powder into the metal conduit.

By using nitrogen gas as a carrier gas, deterioration of the polyether ether ketone resin due to oxidation can be prevented, or a mixture thereof may be used.

Thus, the thickness is 0.0! - (A metal conduit l with a corrosion-resistant protective layer 3 formed on the inner surface in a range of 2 km is heated at 3θO℃
As a result of a test in which it was immersed in hot water for an ioo hour, the corrosion-preventing effect was good, no peeling or cracking was observed in the corrosion-resistant protective layer 3, and it was found that it could sufficiently withstand salt water. Understood.

Furthermore, in the above, short silica glass fibers or quartz powder is added to the polyetheretherketone resin.

Alternatively, a similar effect was found in tests in which a corrosion-resistant protective layer was formed using composite powders mixed with alumina powder.

On the other hand, instead of polyetheretherketone resin, epoxy resin or vinyl chloride resin powder is used.

The corrosion-resistant protective layer formed by the method of this invention is 30d'C
It was confirmed that cracks occurred in hot water, making it impossible to put it to practical use.

FIG. 2 shows another embodiment of the discharge electrode used in the method of the present invention, in which a plurality of protruding blow-off holes /l are provided on the side wall of the discharge electrode lθ made of a metal pipe, and a polygon is formed in the hollow part of the discharge electrode IO. Ether ether ketone resin powder flow. The pressure inside the metal conduit (not shown) is reduced in advance, and the powder blown out from the blow-off hole l/ is charged by corona discharge generated at the tip of the blow-off hole. By using the discharge electrode 10 having such a protruding blow-off hole 11, the electric field at the tip of the blow-off hole/l can be increased, so that there is an effect of generating corona discharge at a low voltage.

Thus, the metal conduit having the corrosion-resistant protective layer formed on its inner surface is coated with an appropriate electrically insulating coating on its outer surface, and is used as an electrode support conduit.

As described above, the present invention provides the above-mentioned (a), (b) +' (C) which the corrosion-resistant protective layer formed on the inner surface of the electrode supporting conduit for electrically heating underground hydrocarbon resources should have.
The present invention has the effect that it satisfies the characteristics of pipes and can easily manufacture desired pipes, even if they are long or thin.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an apparatus for explaining one embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of another embodiment of a discharge electrode used in the present invention. No. Metal conduit, 2. Induction heating coil, 3. Anti-corrosion protective layer, Hiroshi... Discharge electrode, S. Flange, L. DC power supply, g. Inlet, 9. Discharge port. , io...Discharge electrode, l/...-Blowout hole. Agent Shin Kuzuno −

Claims (1)

[Scope of Claims] (1) A discharge electrode is disposed inside the metal conduit along the axis of the metal conduit (7, by applying a DC voltage between the discharge electrode and the metal conduit, the discharge electrode is A corona discharge is generated in the vicinity of the electrode, and the powder made of polyetheretherketone resin, which is introduced into the metal conduit together with a carrier gas, is charged with the corona discharge, and the electric potential of the metal conduit is changed. A method for producing an electrode support conduit for electric heating of hydrocarbon underground resources, characterized in that a corrosion-resistant protective layer is formed by the powder on the inner surface of the metal conduit due to a potential difference with the potential of the discharge electrode. (2) Metal A method for producing an electrode supporting conduit for electric heating of hydrocarbon underground resources according to claim 1, which comprises heating the conduit in advance. (3) The powder is polyether ether ketone resin, silica glass short fiber 9 quartz powder. The method for producing an electrode supporting conduit for electric heating of hydrocarbon underground resources according to claim 7, wherein the carrier gas is a mixture of at least one selected from alumina powder and alumina powder. A method for producing an electrode supporting conduit for electric heating of hydrocarbon underground resources according to claim 1. (Claim 7 in which the discharge electrode 51 is a metal core wire)
A method for producing an electrode supporting conduit for electric heating of hydrocarbon underground resources as described in 2. (A) The discharge electrode is a metal pipe having a plurality of protruding outlets on the surface, and powder is introduced into the metal pipe, and the powder is removed by the pressure difference between the inside of the discharge electrode and the inside of the metal conduit. The electrode support for electric heating of hydrocarbon underground resources according to claim 7, which generates corona discharge between the metal conduit and the tip of the blow-off hole when the metal conduit is blown from the blow-off hole into the metal conduit. Method of manufacturing conduit.