Downhole Cables with Optical Fiber and Copper Elements

ES 2 565 239 T3

DESCRIPTION

Well cables with copper and fiber elements

Cross reference to related requests

This application claims the priority of provisional application US 60/823959, filed on August 30, 2006.

Field of Invention

1. Field of Invention

The apparatus and methods consistent with the present invention relate to a hybrid well cable and, more particularly, to a hybrid well cable having both copper and fiber elements.

two. Description of Related Art

Hybrid cables with fiber and a copper wire are used for several purposes. For example, they are used to supply power through the copper wire while detecting the fiber. Furthermore, the detection can also be done by means of the copper wire. Such hybrid cables have also been used in manhole cables for use in wells. The logging cables are intended to be placed inside, for example, an oil well to collect measurements from samples of the well structure. After completing the measurements, and verifying that the data has been collected, the log wire is removed from the oil well.

Existing technology (see Figure 1) for hybrid type well cables having both fiber and copper elements includes (1) a fiber / gel filled stainless steel core tube (4) with a copper wire ( 6) wrapped around the tube and an insulating layer around the copper wire / tube, configuration that is produced by Gulf Coast Downhole Technologies located in Houston, TX. Another existing structure (2) has a central copper wire insulated with small plastic tubes filled with fiber gel with an insulator around it. This structure (2) is produced by Draka.

The disadvantage of the article (1) is that the copper wire 6 is not easily separated from the stainless steel tube (4). Attaching the sensing elements to the cable, when the cable is finished, ie disassembled, is a complicated procedure. The user needs to ensure that the copper wire is separated from the stainless steel tube and it has to be insulated again and the insulation has to be removed to obtain the copper wires. Another disadvantage is that the stainless steel central tube has to be of such a size that the excess fiber length (EFL) inside the tube must be relatively low, in the case where a multi-mode optical fiber is extended within it. . This fiber is commonly used for temperature sensing, so it is often used in this type of tube. Mono-mode fiber optics are also used in the well for detection. It is less sensitive than multi-mode fiber optics, so excess fiber may be slightly larger, but since multi-mode and mono-mode fiber optics are commonly run on the same cable, excess fiber length will be handled. by multi-mode fiber. If the stainless steel tube is about 2 millimeters (0.080 inches) or less, then the EFL can only be 0.10 to 0.15% of the length of the fiber inside the core to still have good performance. optical. This limits the amount of tension that the cable can feel before the fiber is also under tension. This can be a problem for environments where the temperature of the cable will rise.

More particularly, in fiber optic well cables, a 6.35mm (1/4) metal tube is used to house the fiber optic core. With this diameter and the tube wall thickness of 6.35 mm (1/4), typically 0.71 mm or 0.89 mm (0.028 or 0.035), the inside diameter of the metal tube is 6.35 mm (1/4) is fixed. This results in the cable designer being required to work in a small space to accommodate the desired copper and fiber elements. To fit a 2 mm (0.080 inch) fiber filled stainless steel tube within this 6.35 mm (1/4) tube and to include the copper elements with the appropriate level of insulation to ensure proper performance of the copper, the size of the stainless steel tube is limited.

In general, as the size of the stainless steel tube increases, more excess fiber can be drawn into the tube and still have acceptable optical performance (too much fiber can create optical loss). Excess fiber is needed within the stainless steel tube to ensure good optical performance during temperature changes within, for example, the oil well. As the temperature rises, the metal expands faster than the fiber, and in the absence of excess fiber inside the stainless steel tube, the fiber would be under tension while the temperature increases. High tension reduces fiber life, can increase attenuation (optical loss), and can affect other attributes of the fiber. In a single tube configuration of the article (1), with the copper wire wrapped around the tube, the geometry is such that the center of the stainless steel tube is small, that is, 2 mm (0.080 inches) or less. This is a drawback in this type of design, since the size of the center of the stainless steel tube limits the EFL within the tube.

ES 2 565 239 T3

Item (2) overcomes the EFL problems of Item # 1 by braiding the plastic tubes around the insulated copper wire. However, due to the size of the plastic tubes, the amount of benefit is limited. Braiding provides radial movement of the fibers within the tube, which increases the amount of cable tension experienced by the plastic tubes before the fiber experiences tension. However, with this structure, the disadvantage is that the inherent strength of the structure is limited because the strength of the structure element is only in the central copper wire. This becomes problematic, as processing stresses in the core and installation practices can result in high levels of stress in the cable, thus exposing the fiber under tension. Another disadvantage of article (2) is its resistance to being crushed. The plastic tube limits the amount of external force that can be applied to it, to still have good optical performance.

GB2240638 describes a fiber optic cable with a core provided with helical braided A elements. A metal tube B containing optical fibers is supported by the core.

Document US2001 / 0032730 describes a metallic optical overhead cable comprising a metal tube having a longitudinal weld seam and containing one or more optical waveguides and a metal wire which is connected to the metal tube in a locking manner. force or form.

Document WO 00/72071 discloses a submarine optical cable with a sheath and a core comprising optical fibers that are encased in a metal tube. The tube is arranged near the axis of the cable. The cable comprises at least two metal tubes that are twisted in SZ.

Summary of the invention

Exemplary embodiments of the present invention overcome the above disadvantages and other disadvantages not described above. Furthermore, the present invention does not need to overcome the disadvantages described above, and an exemplary embodiment of the present invention may not overcome some of the problems described above.

According to a first aspect, a method of manufacturing a cable is provided, the method comprising: forming a first helical shape on a first outer circumferential surface of a first metal tube, the first metal tube having a fiber element housed in the same; and braiding a first copper element in a helical space formed by the metal tube.

According to a second aspect, there is provided a cable for wells comprising:

a metal tube comprising: a first metal tube having a helical shape on a first outer circumferential surface thereof, wherein the first metal tube has a fiber element housed therein; and a first copper element stranded in a helical space formed by the metal tube.

The present invention provides a well wire that increases a stress free window of the well wire.

The present invention also provides a well wire that can be elongated by tension or temperature, without unduly forcing an optical fiber into an element in the well wire.

The foregoing and other objects of the present invention are further achieved by providing a method of manufacturing a cable that includes forming a first helical shape on a first outer circumferential surface of a first metal tube, the first metal tube having a fiber element. housed inside, and braiding a copper element in a helical space formed by the first metal tube.

The first metal tube can be a stainless steel tube filled with fiber gel or it can be gel free.

In accordance with yet another aspect of the present invention, a cable is provided that includes a first metal tube having a helical shape on a first outer circumferential surface thereof, where the first metal tube has a fiber element housed therein. interior, and a copper element stranded in a helical space formed by the first metal tube.

The method may further comprise: forming a second helical shape on a second circumferential surface of a second metal tube; place the first metal tube, and the second metal tube parallel to the first metal tube, such that the first outer circumferential surface of the first metal tube is in contact with the second circumferential area of ​​the second metal tube, in a braiding machine; placing the first copper element and a second copper element in the interstitial areas of the first metal tube and the second metal tube, in the braiding machine; and braiding the first metal tube, the second metal tube, the first copper element, and the second copper element together by activating the braiding machine; where the braiding further comprises braiding the first copper element in a first interstitial space

ES 2 565 239 T3 helical of the first helical shape on the first circumferential surface and the second helical shape on the second circumferential surface, and braiding the second copper element in a second helical interstitial space of the first helical shape on the first circumferential surface and the second helical shape on the second circumferential surface.

Braiding further includes helixing the first metal tube, the second metal tube, the first copper element, and the second copper element together.

Before the placement of the first metal tube and the second metal tube, the method further includes forming a first helical shape on the first circumferential surface of the first metal tube, and forming a second helical shape on the second circumferential surface of the second tube. of metal, wherein the braiding further comprises braiding the first copper element in a first helical interstitial space of the first helical shape on the first circumferential surface and the second helical shape on the second circumferential surface, and braiding the second copper element in a second interstitial space helical of the first helical shape on the first circumferential surface and the second helical shape on the second circumferential surface.

The method may further include placing a plastic extrusion at a distal end of the first braided metal tube, the second metal tube, the first copper element, and the second copper element.

The cable may further comprise: a second metal tube parallel to the first metal tube, such that the first outer circumferential surface of the first metal tube is in contact with a second circumferential area of ​​the second metal tube; and a second copper element, the first copper element and the second copper element arranged in the interstitial areas of the first metal tube and the second metal tube.

Brief description of the figures

The foregoing and / or other aspects of the present invention will become more apparent from describing certain exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

Figure 1 shows a hybrid type well cable that includes a metal tube with copper wire wrapped around the tube and an insulating layer around the copper wire, where the metal tube is not preformed.

Figure 2 shows a cross section of a well cable according to a first embodiment of the present invention;

Figure 3 shows a side view of a metal tube and the braided copper element in the helical spaces formed in the metal tube during a method of manufacturing the well cable of the first exemplary embodiment of the present invention;

Fig. 4 shows another side view of the metal tube and the copper element that is braided in the center in the braiding process during the well cable manufacturing method of the first exemplary embodiment of the present invention;

Figure 5 shows a preform making the helical shape on the circumferential outer surface of the metal tube;

Figure 6 shows a cross section of a double tube well cable in accordance with a second exemplary embodiment of the present invention; Y

Figure 7 shows a cross section of a multi-tube well cable according to a third exemplary embodiment of the present invention.

Detailed description of exemplary embodiments

Certain exemplary embodiments of the present invention will now be described in greater detail with reference to the accompanying figures.

In the following description, the same reference numbers in the drawings are used for the same elements, even in different figures. Topics defined in the description, such as detailed construction and elements, are provided to aid in a thorough understanding of the invention. Thus, it is clear that the present invention can be carried out without these specially defined issues. Furthermore, well-known functions or constructions are not described in detail, as these would obscure the invention in unnecessary detail.

A well cable according to an exemplary embodiment of the present invention, and a method of manufacturing the well cable of this exemplary embodiment, will be described with reference to Figure 2 and Figure 3. Figure 2 shows a cross section of a well cable in accordance with the first exemplary embodiment of the present invention.

ES 2 565 239 T3

The well cable 10-1, shown in Figure 2, includes a metal tube 14, and the copper element 16, and the jacket 20 and a metal tube 22. As shown in Figure 2, the metal tube 14 has a fiber element 18 housed therein. Figure 3 shows the metal tube 14 of Figure 2 with a helical shape (141, 142) in an outer circumferential area thereof, and a copper element 16 disposed within the helical space formed by the metal tube.

In this exemplary embodiment, metal tube 14 is a fiber gel filled stainless steel tube with a diameter of 2.006mm (0.079). However, the metal tube 14 can be made of Incoloy 825, Inconel 625, or any other type of metal.

The copper element 16 is a copper wire, which is an American Wire Gauge (AWG) conductor 18, with a diameter of 2.006 mm (0.076). The sleeve 20 may be a plastic extrusion that can be placed over an upper end of the metal tube 14 and the copper element 16. In this exemplary embodiment, the sleeve 20 has a diameter of 4.29 mm (0.169), but the sleeve 20 is not limited to this diameter.

The core, that is, the metal tube 14 and the copper element 25 16, are placed within the metal tube 22. The metal tube 22 can be made of Incoloy 825, stainless steel (SS) 316, or any other suitable metal. The wall thickness of the metal tube 22 can vary depending on the desired requirements of a customer. Common wall thicknesses are 0.71mm (0.028), 0.89mm (0.035), and 1.2mm (0.049), but the present invention is not limited to these wall thicknesses. The metal tube 22 has a diameter of 6.35mm (1/4). The core goes inside the 6.35mm (1/4) metal tube with a wall thickness of 0.89mm (0.035). However, the core is not limited to these thicknesses. As would be obvious to one skilled in the art, the present invention can be adapted for other wall thicknesses. In this exemplary embodiment, the well wire is for a fixed installation.

Next, an exemplary method for manufacturing the well wire shown in Figure 2 is described with reference to Figures 2 to 5. A coated copper element 16 and metal tube 14 are placed in a braiding machine. Braiding machines are well known in the art. The copper element 16 and the metal tube 14 are in mechanisms that control the tension of each element to ensure consistency in the braiding process. These two elements are guided from their tension control mechanisms to the point where they meet. At this point, as shown in figure 5, a preformer is located through which the metal tube 14 passes. This preformer 100 is used to impart a permanent helical bend in an element, so that it retains this shape in the structure of the cable. In the most common type of preformer 100, it is a series of three rollers (102a, 102b and 102c) that hold the element (the metal tube 14) that will pass, with the ability to adjust the distance of the first (102a) up to the third roller (102c), while the second roller (102b) can be adjusted to create a gap necessary to obtain the desired curvature of the fastened element, in this case, the metal tube 14. As shown in Figures 3 and 4, a helical shape 141, 142 is cast on a circumferential outer surface of metal tube 14 in the preforming process by means of rollers 102a, 102b, and 102c.

The effectiveness of the back braiding of the copper element 16 and the metal tube 14 as a whole is crucially dependent on the precision of the preform of the stainless steel tube 14. A high level of precision is required in the preform process to ensure that the element of Copper 16 and metal tube 14 are twisted evenly, as shown in Figure 3. The resulting diameter of the two braided elements has a typical variation of <0.102mm (0.004). This variation is an exemplary non-limiting variation, and the present invention does not require this variation as a firm necessity for the copper element 16 and the metal tube 14 stranded to be inserted within the metal tube 22. The metal tube 22 may allow greater variation. To achieve this level of variation, the control of the tension of the two elements must be fair and very low, and allow control of the tension in the two elements individually. In the exemplary embodiment shown in Figure 3, the preforming of the metal tube 14 and the braiding of the copper element into a helical shape formed by the metal tube 14, result in a twist diameter Dt 'equal to a diameter D14 of the metal tube 14 plus the diameter D16 of the copper element 16. That is, Dt '= D14 + D16. Accordingly, according to this exemplary embodiment of the present invention, the twist diameter Dt 'is reduced by the length of a diameter D16 of the copper element 16 when compared to the braiding of the copper element 6 on the metal tube. 4, which did not go through the preforming process, as shown in figure 1.

In particular, as shown in figure 1, a resulting torsional diameter Dt (after the copper wire 6 is wrapped around the stainless steel tube 4 that has not been preformed), is equal to a diameter D4 of the tube of steel 4 plus twice the diameter D6 of the coated copper wire 6. That is, Dt = D4 + 2x + D6. As such, if the metal tube 4 is not preformed, the core will need to be inserted into a larger metal outer tube, thus increasing manufacturing costs.

As the tension varies, the quality of the helical shape 141, 142, formed in the metal tube 14 will degrade, which will cause the resulting diameter to vary. This is critical because of the need for the braided copper element 16, and the metal tube 14, to be inserted into the metal tube 22 and to be able to slide into the tube 22 with minimal effort. If the helical shape 141, 142, molded into the metal tube 14 is not formed properly, that is, either the metal tube 14 is excessively preformed (the helical diameter is

ES 2 565 239 T3 too large) or the preform is too small (resulting in an essentially straight steel tube with the copper wire wrapped around it), the two elements will be forced into place during the insertion process into the tube metallic 22. This results in unwanted compression and tension on the copper element 16 and the metal tube 14, which can compromise the performance characteristics of the copper element 16 and fiber 18 housed within the metal tube 14.

In this exemplary embodiment, the tension for each element (the copper element 16 and the metal tube 14) were kept different to achieve the same tension in each element. This is due to a post-processing phase, when the copper element 16 and the metal tube 14 are in a relaxed state or a tension-free state, the two elements will relax in the same proportion, so that the linear length resulting from these elements is the same. If this is not done, the member having less tension relative to the other member would flex out of position to absorb the resulting compression imparted from the other, more stressed member. This can result in processing problems during the procedure of adding the plastic sleeve 20 to the two elements and placing the two elements within the metal tube 22. If an element between the copper element 16 and the metal tube 14 has a lower stress relative to the most stressed element, the less stressed element can flex out of position and can be damaged in various ways. For example, it can get caught by production equipment or bend over on itself, especially on copper wire.

After the metal tube 14 is preformed, it continues to what is called the closure point, where the copper element is guided as well. As shown in Figure 4, since the copper element 16 is significantly less hard than the stainless metal tube 14, the copper element 16 will form the helix of the stainless steel tube. In other words, the metal tube 14 and the copper element 16 are twisted concentrically about their center, as shown in figure 4. After this point, the two elements, which are now twisted together, are guided at the entrance of the machine.

In this exemplary embodiment, each copper element 16 and metal tube 14 have a diameter of approximately 1.98mm (0.078). After these two elements are braided together, a plastic extrusion 20 is then placed over them to hold them together. This plastic is not required in the exemplary embodiment, but can be provided as an additional feature. The diameter of the extrusion is approximately 4.34mm (0.171). This structure is then inserted, for example, into the 6.35mm (1/4) metal tube 22 with a wall thickness of 0.89mm (0.035), so that the resulting inner diameter of the 6mm metal tube , 35mm (1/4) is 4.57mm (0.180). The structural dimensions are not critical and can be adjusted to other element sizes, that is, a different dimension of the copper element 16 and a different dimension of the fiber-filled stainless metal tube 14, and the outer tube 22 is not required to have a diameter. 6.35mm (1/4) or 0.89mm (0.035) wall thickness.

Next, a double tube well cable according to a second exemplary embodiment of the present invention and a manufacturing method of the double tube well cable will be described with reference to FIG. 6.

Figure 6 shows a cross section of a double tube well cable 10-2, in accordance with the second exemplary embodiment of the present invention.

As shown in Figure 6, the well cable 10-2 includes a first metal tube 14a, a second metal tube 14b, where both the first metal tube 14a and the second metal tube 14b have the element fiber 18 housed therein. Well cable 10-2 further includes a first copper element 16a and a second copper element 16b.

As shown in Figure 6, the second metal tube 14b is positioned parallel to the first metal tube 14a. A first circumferential surface of the first metal tube 14a is in contact with a second circumferential area of ​​the second metal tube 14b. The first and second copper elements (14a and 14b) are placed in interstitial areas 24 of the first metal tube 14a and the second metal tube 14b.

The plastic jacket 20 holds the first metal tube 14a, the second metal tube 14b, the first copper element 16a, and the second copper element 16b are held together by the plastic jacket 20. This combination can then be introduced into of metal tube 22, similar to the well wire illustrated in Figure 2.

The characteristics of the first metal tube 14a, the second metal tube 14b, the first copper element 16a, the second copper element 16b, the plastic jacket 20, and the metal tube 22, may vary as described above with respect to Figure 2. For example, in this exemplary embodiment, the copper element 16 may be a 21 AWG conductor. The diameter of the first metal tube 14a, and the second metal tube 14b, may be 1.17mm (0.046), but is not limited to this limitation.

To make the double tube well wire 10-2 shown in Figure 6, the first metal tube 14a, the second metal tube 14b, the first copper element 16a, and the second copper element 16b are stranded.

ES 2 565 239 T3 with each other at the same time. Each of the elements 14a, 14b, 16a and 16b are placed in a braiding machine. At the point where these elements would meet, the braiding machine mechanism is designed to control the desired positions of the fasteners. Once the first metal tube 14a, the second metal tube 14b, the first copper element 16a, and the second copper element 16b are in the desired positions, that is, the first metal tube 14a and the second tube metal 14b are in contact with each other, the first copper wire 16a and the second copper wire 16b are located in the interstitial areas of the first metal tube 14a and the second metal tube 14b, and these are twisted together to form the nucleus. This method of braiding is called planetary braiding, where the individual elements are braided in such a way that they are not twisted on their own axis, but wrapped with the other elements.

Unlike cable 10-2 of the first exemplary embodiment shown in Figure 2, in double tube cable 10-2 of this exemplary embodiment, the metal tube 14a and the second metal tube 14b do not have to pass through of the preforming process shown in Figure 5. Preforming of the first metal tube 14a and the second metal tube 14b may be an optional feature. The preforming of the first metal tube 14a and the second metal tube 14b is not necessary when the tube 14a and the tube 14b have the same characteristics. As these components 14a, 14b, 16a, and 16b are helically formed, they twist about the center, resulting in a uniform twist. Therefore, in this case, the diameters of the first copper element 16a and the second copper element 16b would not contribute to the diameter of the resulting diameter of the stranded components (14a, 14b, 16a and 16b), since these are placed in the interstitial helical spaces of the first metal tube 14a and the second metal tube 14b, during the braiding process.

Figure 7 shows a 10-3 multi-tube well cable. The cable 10-3 includes a copper element 16 'and the multiple metal tubes 14' stranded together with the copper element 16 '. The plastic jacket 20 can be placed over the braided elements (16 ', 14') to hold the elements together, to form a core. Subsequently, this core can be inserted into the metal tube 22.

The above embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be quickly applied to other types of apparatus. Furthermore, the description of the exemplary embodiments of the present invention is considered to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.