JPS62151700A - Heat-insulating double pipe - 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 Field of Industrial Application This invention relates to an insulated double pipe used when injecting high-temperature steam etc. underground for the tertiary recovery of crude oil in an oil well. Must be related to.

Conventional technology In general, in the recovery of petroleum resources, in the initial stage after oil well drilling, crude oil can be recovered by self-injection due to natural pressure within the crude oil-containing layer or by being pumped up from the ground surface (-next recovery). , when the natural pressure underground drops, water or gas is injected to increase the pressure, and the pressure is used for recovery (secondary recovery). However, if recovery becomes difficult, it is possible to increase the fluidity of the crude oil by injecting high-temperature steam underground to raise the temperature, or by injecting chemicals to increase the fluidity of the crude oil and pump it to the surface (tertiary recovery). It is being done.゛When injecting high-temperature steam underground in the above-mentioned tertiary recovery, it is necessary to prevent the temperature of the high-temperature steam from decreasing due to heat loss from the pipe walls while it reaches the underground crude oil-containing layer. Therefore, it is desirable to use an insulated double pipe to inject high-temperature steam.

I-insulated double pipes consist of an outer pipe and an inner pipe arranged concentrically with a gap between them, and a heat insulating layer such as vacuum insulation between the outer pipe and the inner pipe, which prevents high-temperature water vapor, etc. from passing into the inner pipe. It is designed to prevent a drop in the temperature of the transported object, and the type shown in FIG. 3 has been the most popular insulated double pipe used for the tertiary recovery of crude oil as described above. This heat-insulating double pipe has a large number of ring-shaped centerizers 2 fitted on the outer circumferential surface of an inner pipe 1 made of a straight J-ply pipe at predetermined intervals in the length direction, and each centerizer 2 It is fixed to an inner tube 1 by welding or the like, and an outer tube 3 made of a straight J' blank tube is arranged so as to concentrically surround the inner tube 1.

In addition, the pipe end portion of such an insulated double pipe (as shown in FIG. Welded and further outer tube 3
It is known that a male screw portion 4 for connection is formed on the outer surface near the tube end of the tube. Here, the centerizer 2 and the expanded tube end 1A of the inner tube 1 cause the inner tube 1 and the outer tube 3 to
A gap is secured between the two to form the heat insulating layer 5.

Problems to be Solved by the Invention In the case of a conventional insulated double pipe having a wrong end at the end as shown in FIG. 3, it is necessary to expand the end when manufacturing the inner pipe 1. When performing 7JI machining, the actual situation is that the tip of the tube end portion should not be made thinner.In this way, if the tip of the expanded tube end portion of the inner tube 1 is thinned, that portion Not only will there be a problem that the strength of the inner tube 1 will be reduced, but also when welding the inner tube 1 with the outer tube 3, the thinner end of the inner tube 1 may be cut, resulting in poor welding.

One way to avoid problems like the above is to thicken the end of the inner tube in advance, but this has the disadvantage of increasing the number of steps and manufacturing costs. . It is also conceivable to cut off the thinned part of the inner tube due to expansion and then weld it to the outer tube, but in this case, the cut off causes a decrease in material yield, which also has the disadvantage of increasing costs by 3G.

The present invention was made against the background of the above circumstances, and it is an object of the present invention to provide a heat-insulating double pipe that does not cause thinning of the pipe end portion as in the prior art.

Means for Solving the Problems This invention provides an insulated double pipe in which an outer pipe and an inner pipe are arranged concentrically and a heat insulating layer is provided between the outer pipe and the inner pipe. is deep drawn to reduce its diameter, and its reduced diameter tip is joined to the tube end of the inner tube.

Function: In the insulated double pipe of the present invention (contrary to conventional insulated double pipes), the pipe end of the outer pipe is reduced in diameter by deep drawing, and the tip of the reduced diameter part is It is joined to the end of the inner tube.When the end of the outer tube is reduced in diameter by deep drawing in this way, compressive force is applied, so the reduced diameter end of the tube is thickened. Therefore, the number of bullets at the end of the outer tube is ensured sufficiently, and no welding defects occur when joining the end of the inner tube by welding.

Embodiment FIG. 1 shows 11 rows of pipe end portions of the insulated double pipe of the present invention.

The outer pipe 3 is made of a non-porous steel pipe, etc., and is used for high-temperature steam injection in oil wells as described above! In the case of heavy pipes, the length is, for example, 9.5rn or 12m,
In addition, its outer diameter is approximately 88.9 to 139.7 g, and its wall thickness is 5.
．． It is approximately 0 to 10.0#. On the other hand, the inner tube 1 is also made of a seamless steel tube, and its outer diameter is, for example, 48.3.
- About 88.98, wall thickness is 3.5 to 10. Roughly speaking, the width of the gap between the outer tube 3 and the inner tube 1, which should become the heat insulating layer 5, is about 5 to 15 rnIn.

The diameter of the tube end portion 3A of the outer tube 3 is reduced by deep drawing,
On the other hand, the inner tube 1 remains straight, and the tip of the reduced diameter tube end 3A of the outer tube 3 is joined to the tube end 1A of the inner tube 1 by welding 6. A male threaded portion 4 is formed on the outer circumferential surface of the straight tubular portion of the outer tube 3 near the tube end 3A to be connected to another adjacent insulated double tube using a jig 7.

Here, since the reduced diameter tube end 3A of the outer tube 3 has been reduced in diameter by deep drawing, it is subjected to compression processing during the deep drawing process, and is rather thickened.

As mentioned above, as a specific method for reducing the diameter of the tube end 3A of the outer tube 3 by deep drawing L), an oil bath deep drawing machine is used to reduce the diameter of a long steel tube of 9IrL or more. Since it is difficult to process the tube ends, it is desirable to use an upsetter for thickening the tube ends, for example, as described below.

An upsetter is a device that increases the thickness of a long steel pipe by holding the end of the pipe with a die and applying compressive force in the axial direction from the end of the steel pipe with a punch. Deep drawing of the tube end is performed using a similar upsetter. That is, as shown in FIG.
is held, and the tube end portion 3A of the outer tube 3 is deep drawn by the compressive force of the punch 10 in the tube axis direction. Although this processing may be performed cold, it is preferable to perform the above-mentioned processing after heating the tube end portion 3A of the outer tube 3 by induction heating, as in the case of normal upset processing.

In the example shown in FIG. 1, the tip of the tube end 3A of the outer tube 3 is connected to the inner tube 1.
Although the inner tube 1 is welded to the outer surface of the distal end thereof, it goes without saying that it may be welded to the distal end surface of the inner tube 1 depending on the case. In addition, in the example shown in FIG. 1, a centerizer 2 is provided between the outer tube 3 and the inner tube 1, but instead of this centerizer 2, the outer tube 3
A dimple portion that protrudes inward may be formed on the circumferential surface of the substrate.

Effects of the Invention In the insulated double pipe of the present invention, thinning of the pipe end of the steel pipe constituting the insulated double pipe is effective (this can be prevented, and the strength of that part may be reduced or welding defects may occur). In addition, there is no need to increase the thickness of parts that are expected to become thinner, so there is no increase in the number of processes, and there is no need to cut off parts that have become thinner. Various effects such as improved yield can be obtained.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of a main part showing an example of the insulated double pipe of the present invention, and Fig. 2 is a schematic cross-sectional view showing an example of a method of deep drawing the inner pipe of the insulated double pipe of the present invention. 3 are longitudinal sectional views of essential parts showing an example of a conventional heat-insulating double pipe. 1... Inner tube, 3... Outer tube, 3A... Pipe end of outer tube, 5... Heat insulating layer.

Claims (1)

[Scope of Claims] In an insulated double pipe in which an outer pipe and an inner pipe are arranged concentrically and a heat insulating layer is provided between the outer pipe and the inner pipe, the end of the outer pipe is deep drawn and contracted. An insulated double pipe characterized in that the diameter of the pipe is reduced, and the reduced diameter tip is joined to the pipe end of the inner pipe.