JP2006301009A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical fiber cable with which an optical sensor system exploration is carried out even at a temperature of 300 °C or higher corresponding to a depth of 10 km or larger in an oil exploration/drilling work. <P>SOLUTION: The optical fiber cable can be used even at such a place exposed to a high temperature as a temperature monitoring sensor system in an oil drilling or the like because the outer layer side of an optical fiber 11 is cooled by a cooling means 20, and exploration using the optical sensor system is materialized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical fiber cable, for example, a heat-resistant optical fiber cable provided with a cooling mechanism used in a temperature monitoring sensor system such as oil well mining, and can be used even at a high temperature of 300 ° C. or higher. It is about the cable.

In recent years, in a temperature monitoring sensor system used for oil well mining, a sensor based on an optical signal has been increasingly used from a sensor based on an electric signal that has been conventionally used because of its effectiveness (see, for example, Patent Document 1). .
The sensor in this temperature monitoring sensor system is used in the form associated with an oil well drill. Therefore, it is usually used at a depth of 2 to 3 km from the ground, and the ambient temperature reaches 150-200 ° C. due to geothermal heat. Until now, in the optical fiber cable used in this environment, the optical fiber cable material has been made of metal, and the fiber coating material has been made of heat-resistant polyimide resin or Teflon resin.

FIG. 7 illustrates an optical fiber cable conventionally used. FIG. 7A is a transverse sectional view, and FIG. 7B is a longitudinal sectional view.
As shown in FIG. 7, in a general optical fiber cable 100 used for oil well exploration, the outer layer 101 is made of metal such as Inconel having excellent heat resistance and anticorrosion, and the inner layer 102 is excellent in heat resistance. Metal such as stainless steel is used. A jelly 103 is used inside the inner layer 102 for the purpose of waterproofing, and an optical fiber 104 covered with a heat-resistant material as described above is housed in the center.
JP-A-6-300944

  By the way, the exploration depth of oil wells tends to increase year by year (currently 5-7 km, and in the future we are considering up to 10 km). It is considered to be. For this reason, the heat-resistant temperature required for the optical fiber cable is also required to be 300 ° C. or higher, and the conventional optical fiber cable as described in FIG. 7 cannot withstand high temperatures and cannot perform appropriate measurement. There was an inconvenience.

  The present invention has been made in view of the above-described problems, and its purpose is to perform optical sensor system exploration even at a high temperature of 300 ° C. or higher corresponding to a depth of 10 km or more in an oil well exploration / mining business. It is to provide an optical fiber cable.

  In order to achieve the above-described object, an optical fiber cable according to the present invention has a storage space for storing a coated optical fiber, and includes cooling means for cooling the optical fiber through the storage space. It is characterized by.

In the optical fiber cable configured as described above, the outer layer side of the optical fiber is cooled by the cooling means, so that it can be used in places exposed to high temperatures such as temperature monitoring sensor systems such as oil well mining. Exploration using an optical sensor system becomes possible. Here, the term “optical fiber” refers to an optical fiber coated with a resin coating around a bare fiber consisting of a core and a clad.
Further, by cooling the optical fiber by the cooling means and storing the optical fiber in the storage space, it is possible to prevent the space from serving as a heat insulating material and causing the optical fiber to reach a high temperature.

  In addition, as described above, the optical fiber cable according to the present invention is characterized in that the storage space for storing the optical fiber is filled with a gel-like material.

  In the optical fiber cable configured in this way, waterproofing can be achieved by filling the storage space provided on the outer layer side of the optical fiber with a gel substance.

  In addition, as described above, the optical fiber cable according to the present invention is characterized in that the gel-like material is gelled at 300 ° C.

  In the optical fiber cable configured as described above, even if the optical fiber cable is exposed to a high temperature of 300 ° C. or higher, the gel-like material is interposed, so that the optical fiber is not deteriorated even if the optical fiber receives a lateral pressure.

Further, as described above, the optical fiber cable according to the present invention includes a cooling means for cooling the optical fiber, and the cooling means is provided in the cable, and a coolant is provided in the longitudinal direction of the cable. Even if the tip of the cable is exposed to a high temperature of 300 ° C. by injecting the coolant into the cooling tube, the surface temperature of the optical fiber is 10 m from the tip. It is characterized by being 100 ° C. or lower.

  In the optical fiber cable configured as described above, even if the tip of the cable is exposed to a high temperature of 300 ° C. by the cooling means, the surface temperature of the optical fiber becomes 100 ° C. or less at 10 m from the tip of the cable. Therefore, the optical fiber can be used even in a high temperature environment.

  The optical fiber cable according to the present invention includes a cooling means for cooling the optical fiber, as described above, and is characterized in that the cooling pipes are provided at two or more locations in the cable.

  In the optical fiber cable configured as described above, since the optical fiber is cooled by cooling pipes provided at two or more locations in the cable, the external temperature is shut off even in a higher temperature environment, and the internal temperature is kept below a predetermined temperature. And can be used at high temperatures.

In addition, as described above, the optical fiber cable according to the present invention is provided with cooling pipes filled with a coolant as cooling means for cooling the optical fiber at two or more locations in the cable. The cross-sectional area of the coolant flow path is in the range of 6.0 to 24.0 (mm ² / tube).

In the optical fiber cable configured in this way, the outer diameter of the optical fiber cable is desired to be as thin as possible from the viewpoint of cost and structure, but if it is too thin, the coolant cannot be supplied smoothly and it is difficult to obtain a sufficient cooling effect. become. For this reason, by restricting the cross-sectional area of the coolant flow path of the cooling pipe to the range of 6.0 to 24.0 (mm ² / tube), it is possible to prevent the outer diameter from becoming large and to sufficiently cool the cooling pipe. An effect was obtained.

  Further, as described above, the optical fiber cable according to the present invention is provided with cooling pipes filled with a coolant as cooling means for cooling the optical fiber at two or more locations in the cable, It is a low-temperature liquefied gas such as liquid helium or liquid argon.

In the optical fiber cable configured in this way, the cooling pipe is filled with an ultra-low temperature liquefied gas such as liquid helium or liquid argon to cool the optical fiber, so that the high temperature can be prevented from reaching the inside, It is possible to prevent the optical fiber from becoming high temperature.
Needless to say, the low-temperature liquefied gas is an incombustible gas such as an inert gas.

  In addition, as described above, the optical fiber cable according to the present invention is provided with cooling pipes filled with a coolant as cooling means for cooling the optical fiber at two or more locations in the cable, and one end side of the cable. The coolant is injected into the cooling pipe, the cooling pipe is connected to another cooling pipe in the cable on the other end side of the cable, and the coolant is circulated on the one end side.

  In the optical fiber cable configured as described above, the coolant is circulated through a plurality of cooling pipes, so that the coolant can be reused without being discharged to the outside, both in terms of cost and environment. It is valid.

  In addition, as described above, the optical fiber cable according to the present invention is provided with an outlet for injecting the coolant into the cooling pipe from one end of the cable and allowing the coolant to flow out to the other end of the cable. It is characterized by that.

  In the optical fiber cable configured in this way, even if the liquefied coolant is heated and vaporized, it is discharged from the outlet provided at the other end of the cable, so that the coolant is contained in the cable. It is possible to prevent charging and to supply new coolant smoothly to the other end side.

  In addition, as described above, the optical fiber cable according to the present invention is provided with an outlet for injecting the coolant into the cooling pipe from one end of the cable and flowing the coolant out to the other end of the cable. And the said outflow port contains the through-hole formed in the side surface of the cable of the said other end side, It is characterized by the above-mentioned.

  In the optical fiber cable configured as described above, since the outflow port through which the coolant flows out is included in the configuration including the through hole formed in the side surface of the cable, it can be easily formed, and from the through hole The flowing out coolant rises along the side surface of the cable, and the whole can be efficiently cooled.

  Further, as described above, the optical fiber cable according to the present invention includes a through hole formed on a side surface of the cable with an outlet for allowing the coolant to flow out to the outside. Is in the range of 0.5 to 2.0 mm.

  In the optical fiber cable configured as described above, by providing an appropriate size outlet, the coolant can be held in a filled state in the cooling pipe, and the outflow efficiency of the coolant to the outside can be increased. .

  In addition, as described above, the optical fiber cable according to the present invention is a through-hole serving as an outlet for injecting the coolant into the cooling pipe from one end of the cable and flowing the coolant out to the other end of the cable. The number of the through holes is 2 or more / tube.

  In the optical fiber cable configured as described above, the exhaust efficiency of the coolant to the outside can be increased by providing a plurality of through holes.

  In addition, the optical fiber cable according to the present invention is characterized in that an oil well drilling drill is attached to the distal end side of the cable and a function of monitoring the temperature in the cable on the distal end side of the cable is provided.

  In the optical fiber cable configured as described above, the outer layer side of the optical fiber is cooled by the cooling means, so that it can also be used in places exposed to high temperatures such as temperature monitoring sensor systems such as oil well mining, etc. Exploration using a sensor system is possible.

  According to the present invention, since the outer layer side of the optical fiber is cooled by the cooling means, it can be used in a place exposed to high temperatures such as a temperature monitoring sensor system such as oil well mining. The effect that the exploration that had been possible becomes possible.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the drawings.
FIG. 1 (A) is an explanatory view showing an outline of a system using the optical fiber cable of the present invention for oil well exploration, and FIG. 1 (B) is an explanatory view showing a relationship between depth and underground temperature.
As shown in FIG. 1A, there is a station 1 on the sea, which controls the exploration and excavation work of the oil well 5 on the seabed 2. A pipe 3 for sucking oil from the sea station 1 toward the sea floor 2 is laid vertically, and a drill 4 for making a hole in the sea floor 2 is installed at the tip. The temperature sensor optical fiber cable 10 is a heat-resistant optical fiber cable and is attached to the pipe 3.
As shown in FIG. 1B, the influence of geothermal heat increases as the depth from the seabed 2 increases, and the environmental temperature also rises. For example, it can be seen that the temperature reaches 300 ° C. or more at a depth of 8 to 10 km.

2A is a cross-sectional view showing an optical fiber cable according to an embodiment of the present invention, FIG. 2B is a longitudinal cross-sectional view, and FIG. 2C is an external side view of the distal end portion of the optical fiber cable.
As shown in FIG. 2, the optical fiber cable 10 according to the present invention includes a cooling unit 20 that cools the optical fiber 11 on the outer layer side of the optical fiber 11.
A storage space 12 for storing the optical fiber 11 in the axial center is provided between the optical fiber 11 and the cooling means 20. The storage space 12 is filled with a gel-like material 13 such as a jelly-like waterproof admixture, and the gel-like material 13 is gelled at 300 ° C. Here, the optical fiber 11 refers to a fiber in which a bare fiber 11a composed of a core and a clad at the center is coated with a resin coating 11b.

On the other hand, the cooling means 20 is provided in two locations in the cable, and is a cooling tube 14 and 15 having a hollow structure for allowing a coolant 21 to be described later to flow in the longitudinal direction of the cable. By injecting the coolant 21 into 22a and 22b, even if the tip of the cable is exposed to a high temperature of 300 ° C., it has a cooling ability to make the surface temperature of the optical fiber 100 ° C. or less at 10 m from the tip of the cable. Is.
In this embodiment, the cooling pipes 14 and 15 have a double-pipe hollow pipe structure arranged coaxially. However, the cooling pipes 14 and 15 are not limited to such a configuration. It can also be set as the structure arrange | positioned in the layer.
The cross-sectional area of the flow path of the coolant 21 in each of the cooling pipes 14 and 15 is set in a range of 6.0 to 24.0 (mm ² / tube). That is, it is desired to make the outer diameter of the optical fiber cable 10 as thin as possible from the viewpoint of cost and structure, but if it is made too thin, the coolant 21 cannot be supplied smoothly and it becomes difficult to obtain a sufficient cooling effect. For this reason, by restricting the cross-sectional area of the hollow spaces 22a and 22b to a range of 6.0 to 24.0 (mm ² / tube), it is possible to prevent an increase in outer diameter and to provide a sufficient cooling effect. I tried to get it.

In the hollow spaces 22a and 22b, as the coolant 21, for example, liquid helium (boiling point −270 ° C.), liquid argon (boiling point: −189.2 ° C.), liquid nitrogen (boiling point −210 ° C.), liquid oxygen (boiling point −218). .8 ° C) or the like. The low-temperature liquefied gas is an incombustible gas such as an inert gas, and is fluidly supplied with pressure from the station 1 (see FIG. 1) side.
Thereby, the heat outside the optical fiber cable 10 does not reach the inside of the cooling means 20, and the temperature of the inner portion of the cooling means 20 is cooled and kept below a predetermined temperature.

Further, as shown in FIG. 2C, the coolant 21 injected into the cooling pipes 14 and 15 from one end side (upper end) of the optical fiber cable 10 is applied to the outer surface 23 on the other end side of the optical fiber cable 10. An outlet 24 that can flow out of the optical fiber cable 10 is provided in communication with each of the hollow spaces 22a and 22b. The outlet 24 is formed as a through hole, and is preferably formed within a range of 10 m or less from the other end side (tip portion) of the cable.
Thereby, the coolant 21 can be smoothly supplied to the tip of the optical fiber cable 10, and the whole can be efficiently cooled. Further, even if the liquefied coolant 21 is heated and vaporized, it is discharged from the through hole (24) provided at the tip of the optical fiber cable 10, so that it is prevented from filling the optical fiber cable 10. It is possible to cool the optical fiber 11 stably.

Further, it is desirable that the through holes (24) are substantially circular and have a diameter in the range of 0.5 to 2.0 mm.
Thus, by providing the through-hole (24) having an appropriate size, the coolant 21 can be held in the hollow space 22 while being filled, and the efficiency of the coolant 21 flowing out can be increased. Further, by providing a plurality of through holes (24), it is possible to increase the efficiency of outflow of the coolant 21 to the outside, and to cool the tip of the optical fiber cable 10 efficiently.

About the optical fiber cable 10 comprised as mentioned above, the operation | movement is demonstrated using FIG. 3 and FIG.
First, a measurement method in a temperature monitoring sensor system used for oil well mining will be described. As shown in FIG. 6, part of the optical signal (laser light) that enters from the optical fiber 11 includes backscattered light that has the property of being scattered and returning to the place where the light enters. The intensity of the Raman scattered light contained has a property that changes sensitively with temperature. Therefore, the location and temperature at which the scattered light is generated can be measured from the time until the light incident on the optical fiber 11 returns to the incident side as backscattered light and the intensity of the Raman scattered light. That is, since the propagation speed in the optical fiber 11 is known in advance, it is possible to know the scattered light generated at which point by measuring the round-trip time until the light returns to the light incident side. Scattered light includes two components, Stokes light and anti-Stokes light, which are weak but whose light intensity depends on temperature, and the intensity ratio of these two components is expressed as a function of temperature. Therefore, the temperature of the optical fiber 11 can be obtained by detecting this. Also, it can be divided into a distributed measurement method and a point measurement method depending on the type of fiber used.

The distributed measurement method is a measurement method that uses a multimode fiber and uses light in the 850 nm band or 1400 nm band, and measures temperature changes in a distributed manner over a wide range of several kilometers at intervals of several tens of meters or several meters. This is a method (indicated by α in FIG. 1A).
On the other hand, the point-type measurement method is a measurement method that uses a single-mode fiber and uses light in the 1550 nm band, and is a method of measuring a temperature change at only one point (indicated by β in FIG. 1A).

FIG. 3 shows the structure and temperature distribution example of the optical fiber cable 10 when the point type measurement method is used.
In this measurement method, since measurement is performed at the tip of the optical fiber cable 10, the temperature in the optical fiber cable 10 is kept constant by continuously supplying the coolant 21 at a constant flow rate. Since the temperature of only the oil well 5 portion having the highest external temperature is rapidly increased, when the oil well 5 is present at the tip portion, the temperature inside the optical fiber cable of this portion also rises due to the coolant 21 flowing out from the tip portion. Sensing temperature changes.

FIG. 4 shows an example of an optical fiber cable structure and a temperature distribution when the distributed measurement method is used.
In this measurement method, since measurement is performed in the longitudinal direction of the optical fiber cable 10, it is necessary to adjust the type and flow rate of the coolant 21. As an example, a case where liquid argon is injected into the hollow space 22b of the outer tube 15 and nitrogen gas (liquefaction) is injected into the hollow space 22a of the inner tube 14 at a constant flow rate is shown. In this case, since the cooling action is weaker than when liquid argon is injected into both the hollow spaces 22a and 22b (see the column B in FIG. 5), the heat conduction into the optical fiber cable 10 cannot be completely blocked. Since the temperature in the optical fiber cable 10 located in a very high temperature area where the oil well 5 exists is higher than the temperature in the optical fiber cable in the other area, the temperature change can be sensed. Various combinations of the coolant 21 to be injected into the hollow spaces 22a and 22b are conceivable depending on the external temperature, and adjustment is required each time. FIG. 5 shows the temperature inside the optical fiber cable by other combinations.

As shown in FIG. 5, the combination of the coolant 21 filling the hollow space 22a of the inner layer and the coolant 21 filling the hollow space 22b of the outer layer, the optical fiber cable 10 with respect to an outside temperature of 350 to 400 ° C. It can be seen that the temperatures inside the are greatly different. For example, by filling the hollow spaces 22a and 22b with liquid helium as the coolant 21, the internal temperature can be lowered to -20 to 30 ° C. Therefore, the above-mentioned special materials such as polyimide and Teflon can be used as the coating material. Even if it is not used, the optical fiber 11 using a general-purpose coating material such as nylon (usually usable up to about 85 ° C.) can be used.
Note that the values shown in FIG. 5 are comparisons in the case where the same flow rate of the coolant 21 is supplied to the optical fiber cable 10 having the same structure and the same length.

  As described above, according to the optical fiber cable 10 described above, an optical sensor can be used even at a depth of 10 km or more (300 ° C. or more in terms of heat resistant temperature), which has been difficult to cope with in the oil well exploration and mining business. Exploration using the system becomes possible.

The optical fiber cable of the present invention is not limited to the embodiment described above, and appropriate modifications, improvements, etc. are possible.
For example, in the above-described embodiment, the case where the plurality of outlets 24 are provided on the outer surface of the distal end portion of the optical fiber cable 10 and the supplied coolant 21 flows out to the outside is illustrated. The cooling pipes 14 and 15 having the hollow space 22 provided in multiple layers are prepared while eliminating the outlet, and the coolant 21 is injected into the cooling pipe 15 from one end side of the cable, and at the other end side (tip portion) of the cable. The cooling pipe 15 can be connected to another cooling pipe 14 in the cable, and the coolant 21 can be circulated on one end side of the cable. In this case, the coolant 21 can be reused, which is effective both in terms of cost and environment.

  As described above, since the optical fiber cable according to the present invention cools the outer layer side of the optical fiber by the cooling means, it should be used also in a place exposed to a high temperature such as a temperature monitoring sensor system such as oil well mining. It has the effect of enabling exploration using an optical sensor system. For example, as a heat-resistant optical fiber cable having a cooling mechanism used in a temperature monitoring sensor system such as oil well mining, It is useful as an optical fiber cable that can be used even at high temperatures.

(A) is explanatory drawing which shows the outline | summary of the system which used the optical fiber cable of this invention for the oil well search. (B) is explanatory drawing which shows the relationship between depth and underground temperature. (A) is a cross-sectional view showing an optical fiber cable according to an embodiment of the present invention. (B) is a longitudinal sectional view. (C) is an external side view of the tip of the optical fiber cable. It is explanatory drawing which shows the structure and temperature distribution example of an optical fiber cable at the time of using a point type | mold measuring method. It is explanatory drawing which shows the structure and temperature distribution example of an optical fiber cable at the time of using a distributed measurement method. It is a table | surface which shows the cooling effect with respect to the combination of various coolants in a distributed type measuring method. It is a figure explaining the measurement principle which uses optical fiber itself as a temperature sensor. It is sectional drawing which shows the conventional optical fiber cable.

Explanation of symbols

4 Oil well drill 10 Optical fiber cable, heat-resistant optical fiber cable 11 Optical fiber 12 Storage space 13 Gel-like material 20 Cooling means 21 Coolant 22 Hollow space 24 Outlet

Claims (13)

  An optical fiber cable comprising: a storage space for storing a coated optical fiber; and cooling means for cooling the optical fiber through the storage space.   The optical fiber cable according to claim 1, wherein the storage space is filled with a gel-like material.   The optical fiber cable according to claim 2, wherein the gel-like material is gelled at 300 ° C.   The cooling means is a cooling pipe provided in the cable for circulating a coolant in the longitudinal direction of the cable. By injecting the coolant into the cooling pipe, the end of the cable is exposed to a high temperature of 300 ° C. However, the optical fiber cable according to claim 1, wherein the surface temperature of the optical fiber is 100 ° C. or less at 10 m from the tip.   The optical fiber cable according to claim 4, wherein the cooling pipe is provided at two or more locations in the cable. 5. The optical fiber cable according to claim 4, wherein a cross-sectional area of a coolant flow path of the cooling pipe is in a range of 6.0 to 24.0 (mm ² / tube).   The optical fiber cable according to claim 4, wherein the coolant is a low-temperature liquefied gas such as liquid helium or liquid argon.   Injecting the coolant into the cooling pipe from one end of the cable, connecting the cooling pipe to another cooling pipe in the cable on the other end of the cable, and circulating the coolant to the one end The optical fiber cable according to claim 4.   The optical fiber cable according to claim 4, wherein an outlet for injecting the coolant into the cooling pipe from one end side of the cable and allowing the coolant to flow out to the other end side of the cable is provided.   The optical fiber cable according to claim 9, wherein the outlet includes a through hole formed in a side surface of the cable on the other end side.   The optical fiber cable according to claim 10, wherein the through hole has a diameter in a range of 0.5 to 2.0 mm.   The optical fiber cable according to claim 10, wherein the number of through holes is two or more / tube.   The optical fiber cable according to any one of claims 1 to 12, wherein an oil well drilling drill is attached to the distal end side of the cable, and a function of monitoring the temperature in the cable on the distal end side of the cable is provided.

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