MXPA98007167A - Well recording cable with fiber optic / electric combination - Google Patents

Abstract

The present invention relates to a well logging cable with optical / electrical fiber combination, comprising at least one electrical conductor, isolated, and a plurality of armored or armored wires that encircle the electrical conductor. The armored or armored wires include at least one tube having an optical fiber placed inside the tube. In a preferred embodiment, the armored or armored wires are placed in two concentric layers that circumscribe or limit the electrical conductor. One or more of the armored or armored wires in the innermost layer of armored wires includes the tube that has the optical fiber placed therein. The tube has an external diameter that is substantially the same as the armored or armored wires in the layer in which the tube is located. The inner diameter of the tube is selected to provide enough space for the optical fiber to move around freely, but to have enough compressive strength for the tension and side loads that are expected to be applied to the cable. In a particular modality. The tube includes an inner layer consisting of a thin-walled tube, a layer of sheet metal wrapped around the outside of the inner layer, and an outer layer consisting of another thin-walled tube on the outside of the layer of the outer layer.

Description

WELL RECORDING CABLE WITH FIBER OPTIC / ELECTRICAL COMBINATION DESCRIPTION OF THE INVENTION The invention relates to the field of armored or armored electric cables used in the well register. More specifically, the invention relates to well logging cables, which include one or more optical fibers for communicating data and / or control signals between the surface of the earth and the well logging instruments attached to one end of the well. registration cable. Typically, electric well registration cables include one or more insulated electrical conductors, surrounded by a plurality of steel armored or armored wires that provide the cable with resistance to stress and abrasion resistance. The electrical conductors transmit the electrical energy to the well registration instruments attached to one end of the cable, and transmit the data and / or the control signals between the equipment located on the surface of the earth and the well registration instruments. Some well logging instruments transmit the signal data at such high speeds that it is difficult to use electrical conductors for such data transmission. When such well logging instruments are used, it is desirable to use optical fibers to carry optical data telemetry, since optical telemetry typically has much higher data rate capacity than electrical telemetry. Well logging instruments that use optical data telemetry, preferably, must receive electric power from the surface of the earth through the logging cable, just as for electric telemetry logging instruments, in this way it is A recording cable including a combination of electrical conductors and optical fibers is desirable. Various types of cable with optical / electrical fiber combination are known in the art. A sales brochure entitled "Electro-Optical Mechanical Umbilicals" published by Vector Cable Company, Sugar Land, Tex. (date of unknown publication) shows several configurations for an electric cable that includes both optical fibers and electrical conductors surrounded by armored or steel armored wires. However, the cables described in the Vector Cable Company brochure are typically 1,693 cm. (2/3 of an inch) or more of external diameter, making them impractical for use as a well log cable. Typical well log cables do not exceed approximately 1,346 cm. (17/32 of an inch) external diameter. This is mainly due to the limitations of space in the typical well logging instrumentation system, and as is known in the art also relates to the use of certain well drilling pressure control equipment with line wires, the use of which becomes more difficult to use as the diameter of the recording cable increases. Another type of cable with fiber optic / electric combination is described in U.S. Patent No. 4,697,875 issued to Priaroggia. The cable described in the Priaroggia patent '875 is completely unsuitable for use as a well log cable, because the electrical conductors are externally located to a wire rope resistance member, and are externally covered with a cover of plastic. As is well known in the well logging art, the typical well log wire must have an abrasion resistant material such as steel on the outside. Other well logging cables with optical / electric fiber combination are described in U.S. Patent No. 4,696,542 issued to Thompson and U.S. Patent No. 4,522,464 issued to Thompson et al. The cables described in these patents have limitations with their use as well log cables which are well documented in US Pat. No. 4, 495,547 issued to Rafie et al. And assigned to the agent of this invention. More specifically, the cables described in the Thompson '542 and Thompson et al' 464 patents do not have, to the greatest extent possible, the electrical and mechanical characteristics of the well log cables having only electrical conductors. It is desirable to have such electrical and mechanical properties in a well registration cable to facilitate the use of such recording cables, in situations where the recording instruments attached to the cable only include electrical telemetry, thus avoiding the need to have different cable types available for each type of instrument telemetry system. The Rafie et al. '547 patent discloses various configurations for a well logging cable with optical / electrical fiber combination that retains the preferred electrical and mechanical characteristics of conventional well log cables having only electrical conductors. However, the cables described by Rafie et al. '547 require costly and difficult-to-use connection devices to make electrical and optical connections to the well registration instruments attached to the end of the cable. What is needed is a well logging cable with optical / electrical fiber combination that retains the electrical and mechanical characteristics of a conventional electric well log cable, which has only electrical conductors, and includes the electrical connection capacity and Mechanical to well logging instruments using electrical / mechanical, conventional connection techniques. The invention is a well logging cable with optical / electrical fiber combination. The cable includes at least one insulated electrical conductor and a plurality of armored or armored wires that encircle the electrical conductor. In one embodiment of the invention, the cable includes seven insulated electrical conductors arranged in a regular hexagonal pattern. The armored or armored wires include at least one tube that has an optical fiber placed inside the tube. In a preferred embodiment of the invention, the armored or armored wires are placed in two concentric layers that circumscribe or restrict the electrical conductors. One or more of the armored or armored wires in the inner layer of armored wires includes the tube that has the optical fiber placed therein. The tube has an outer diameter that is substantially the same as the armored or armored wires in the layer in which the tube is located. The inner diameter of the tube is selected to thereby provide enough space for the optical fiber to move around freely, but retain enough compressive strength for the tension and side loads that are expected to be applied to the cable.

In a particular embodiment of the invention, the tube includes an inner layer consisting of a thin-walled tube, a layer of sheet metal wrapped around the exterior of the inner layer, and an outer layer consisting of another thin-walled tube in the outside of the sheet metal layer. The sheet metal layer substantially fills the annular space between the inner layer and the outer layer, so that the tube behaves mechanically in a manner similar to a solid tube having the same internal and external diameters. DESCRIPTION OF THE DRAWINGS Figure 1 is a cross section through a well registration cable according to the invention. Figure 2 shows steel tubes having optical fibers therein, used in replacement of one or more of the armored or armored wires, inside and / or outside of the recording cable shown in Figure 1. Figure 3 shows a design alternative for the steel tubes shown in Figure 2, wherein the tube consists of an inner layer, a sheet metal layer and an outer layer. In Figure 1 a cross section of a well logging cable with optical / electrical fiber combination according to the invention is shown. The recording cable 10 includes a central bundle of conductors 2. The central bundle 2 for the cable 10 shown in Figure 1 includes seven insulated electrical conductors 9 arranged in a regular hexagonal pattern. Each of the electrical conductors 9 can be formed from braided copper wires 12 surrounded by an insulating sheath 8 made of plastic or other suitable flexible, electrically insulating material. Typical dimensions for conductors 9 are described, for example, in a product catalog published by Camesa, Inc., Rosenberg, Tex., Which lists the construction of each of the conductors 9, including seven stranded copper wires each of 0.0325 cm. (0.0128 inches) in diameter, surrounded by an insulating sheath or cover of 0.213 cm. (0.084 inches) of polypropylene or "TEFZEL" (trade name of the copolymer made by E. I. DuPont de Nemours &Co.). The hollow spaces 14 between the conductors 9 within the hexagonal pattern can be filled with a suitable plastic insulating material, well known in the art. It will be clearly understood that the configuration of the central beam 2 shown in Figure 1 is only an example and is not proposed to limit the invention to seven isolated conductors 9. Other configurations acceptable for the central beam 2 are well known in the art and may include a different number of, or different sizes of, electrical conductors. For example, certain smaller diameter well log cables well known in the art include a central beam consisting of only an insulated electrical conductor. Other well log cables include three or four insulated electrical conductors in the central bundle 2. An alternative design to stranded copper conductors, shown in the Camesa, Inc. catalog, is described, for example, in the patent No. 5,495,547 issued to Rafie et al. The alternative electrical conductor 9 may include a copper-coated steel wire of approximately 0.068 cm. (0.027 inches) in diameter surrounded by nine copper wires, each approximately 0.0329 cm. (0.0128 inches) in diameter, all of which are surrounded by a covering or insulating wrap of approximately 0.213 cm. (0.084 inches) in diameter. This configuration for the alternative electrical conductor is shown in Figure 3 in the '547 patent of Rafie et al. Any type of electrical conductor 9 as is accurately described herein, can be electrically connected to well registration instruments (not shown) by the use of sealed electrical connectors, well known in the art. Again with reference to figure 1, the central bundle 2 is typically surrounded by two concentric layers of steel armored or armored wires. The armored wires 4, 6 can also be formed of corrosion resistant alloy such as one known by the trade name MP-35N, where the recording wire is intended to be used in well bores having corrosive fluids therein. Armored or armored wires include interior shielded wires shown at 4, which form the innermost concentric layer. For the cable 10 shown in Figure 1, the armored or armored wires 4 may include eighteen steel wires, each having an external diameter of approximately 0.1294 cm. (0.047 inches). The armored or armored wires 4 are typically themselves surrounded by an outer layer of armored wires 6. For the cable shown in Figure 1, the armored or armored wires 6 may include eighteen steel wires, each having a outer diameter of approximately 0.168 cm. (0.066 inches). It will be clearly understood that other numbers, diameters of, and number of armored or armored wire layers can be used with this invention consistent with minimizing the outer diameter of the cable 10 and at the same time providing commercially acceptable cable breaking strength. 10. The numbers, diameters of, and numbers of layers of the armored or armored wires shown in Figure 1 are only intended to serve as an example of a suitable configuration and are not intended to limit the invention.

In the invention, one or more of the internal armored or armored wires 4, such as one shown in 4A, may consist of a steel tube having an optical fiber placed therein, as will be further explained. Alternatively, or in addition to the tube shown at 4A, one or more of the outer armored or armored wires 6, such as one shown at 6A, may consist of a steel tube having an optical fiber placed thereon, as will be explained further. If the armored or armored wires 4, 6 are formed of a corrosion-resistant alloy, such as the previously described MP-35N, then the tubes 4A, 6A should be formed of the same or a similar material to provide the resistance to the desired corrosion ..

The tube 4A which is replaced by one of the armored or armored wires 4 is shown in more detail in Figure 2. This tube 4A must have an external diameter substantially the same as the outer diameter of the armored wires or inner battles 4, so that the symmetry of the layer of armored or armored wires is maintained. In this example, the outer diameter of the tube 4A, therefore, may be approximately 0.1294 cm. (0.047 inches). An optical fiber 16 placed inside the tube 4A can be of the types known in the art. The fiber 16 shown in this example has an outer diameter of approximately 0.0178 cm. (0.007 inches). The internal diameter of the tube 4A in this example is approximately 0.0584 cm. (0.023 inches). The inner diameter of the tube 4A must be selected to provide enough space for the optical fiber 16 to move about freely within the tube 4A, but also must not be more than that which is reasonably necessary for the optical fiber 16, so that the tube 4A will have sufficient strength to resist compression under the tension and lateral load that is likely to be applied to the cable (10 in Figure 1). Methods for calculating a maximum internal diameter of the tube 4A that will take into account the maximum voltage and lateral load expected in the recording cable 10 are known in the art, including the finite element analysis that can be performed using a computer program sold under the trade name "ANSYS" by Southpoint, 275 Technology Dr., Canonsburg, PA. As previously explained, one or more of the outer armored or armored wires (6 in Figure 1) could also consist of a 6A steel tube (or corrosion resistant alloy tube as previously explained) within which it is placed. an optical fiber 18. In the example in figure 2, the tube 6A can have an external diameter of 0.168 cm. (0.066 inches) and an internal diameter of approximately 0.0584 cm. (0.023 inches) to accommodate optical fiber 18. The external and internal diameters of tube 6A should be selected to meet substantially the same mechanical criteria as tube 4A by replacing one of the internal armored or armored wires (4 in figural). It should be noted that the replacement of one or more of the outer armored or armored wires (6 in Figure 1) by the tube 6A may be less desirable than the replacement of one or more of the armored or armored wires inside (4 in the figural) with the tube 4A, from the point of view of the possibility of failure of the tube 6A due to wear on its outer surface by abrasion with continuous use. The example of the tube 6A is mainly proposed to show that the invention will not be limited in scope to the replacement of armored wires or inner battles 4 by the tube 4A. Figure 3 shows a different design for the tube 4B, which is proposed to facilitate the splicing of the well registration cable at any intermediate position along its length, while maintaining the hydraulic integrity of the tube 4B, so that the fluid under very high pressure, as is typically present in a well bore, can be excluded from the interior of the tube 4B. The tube 4B consists of an outer layer 20, a layer of sheet metal 22 and an inner layer 24. The optical fiber 16 is positioned within the interior of the inner layer 24 in such a manner as it is in the first embodiment of this invention.

The outer layer 20 may be a thin-walled tube, which in this example may have a diameter of about 0.1294 cm. (0.047 inches) and an internal diameter of approximately 0.0939 cm. (0.037 inches). The external diameter of the outer layer 20 is selected in this example for the case where the tube 4B will be included within the inner layer of armored or armored wires in the cable (shown in Figure 1 in 10). The outer layer 20 could also have an outer diameter of approximately the same as that of the armored or armored wires in the outer layer of the armor or armor (6 in Figure 1) if this is where the tube is to be located. The outer layer 20 can be made of steel or of the corrosion-resistant alloy, such as MP-35N used for any of the other armored or armored wires (4 in Figure 1) in the cable.

The inner layer 24 can also be formed from the thin-walled tube. In this example, the inner layer 24 has an internal diameter of approximately 0.0508 cm. (0.020 inches) and an outer diameter of approximately 0.0711 cm. (0.028 inches). The inner diameter of the inner layer 24 must be large enough to allow the fiber 16 to move around freely, but not greater than that necessary to maintain sufficient compressive strength and tensile strength of the tube 4B, such as it is. the case for the first embodiment of the tube (4A in Figure 2) in this invention. The inner layer 24 can be made of the same material as the outer layer 20, but this is not necessary for the construction of the tube 4B. The annular space between the inner layer 24 and the outer layer 20 can be filled with a metal sheet 22 wrapped in a helical pattern around the outside of the inner layer 24. The thickness of the metal sheet 22 should be about the same as the width of the annular space between the inner layer 24 and the outer layer 20. Since the annular space between the outer layer 20 and the inner layer 24 is substantially filled by the metal sheet 22, the tube 4B will have almost the same compressive strength as that of the solid construction tube (4A in Figure 2) in the first embodiment of the invention. It is contemplated that where the recording cable (10 in Figure 1) is to be spliced, the fiber 16 could be coupled using the techniques known in the related media. The inner layer 24 could be coupled using a thin-walled steel sleeve (not shown) that fits over the outside of the inner layer 24 and can be welded or otherwise coupled to exclude fluid entry under high pressure from enter the interior of the inner layer. The metal sheet 22 can be replaced by compressible material such as plastic, or it can be omitted, over the range in which the sleeve is located (not shown). Then the outer layer 20 can be joined by butt welding or the like to provide the mechanical coupling between the ends joined through the splice. The tube 4B in Figure 3 has approximately the same internal and external diameter as the solid construction tube (4A in Figure 2) and retains substantially the same mechanical properties of the solid construction tube (4A in Figure 2), but is better adapted to maintain hydraulic integrity through a splice than the solid construction pipe (4A in Figure 2). Those skilled in the art will devise other embodiments of this invention that do not depart from the spirit of the invention as described herein. Accordingly, the invention will be limited in scope only by the appended claims.

Claims (9)

1. CLAIMS 1. A well logging cable with optical / electrical fiber combination, characterized in that it comprises: at least one insulated electrical conductor; and a plurality of armored or armored wires encircling at least one electrical conductor, the armored or armored wires comprise at least one tube having an optical fiber placed therein. The well registration cable according to claim 1, characterized in that the armored or armored wires are placed in a plurality of substantially cylindrical layers surrounding at least one electrical conductor, the at least one tube has a substantially external diameter the same as an external diameter of the other armored or armored wires placed in one of the concentric layers. The well registration cable according to claim 2, characterized in that the at least one tube has an internal diameter selected to provide free movement of the optical fiber therein and to provide sufficient resistance for the voltage loads and laterals applied to the well log cable. 4. The well registration cable according to claim 2, characterized in that the tube is placed inside an innermost one of the plurality of concentric layers. 5. The well registration cable according to claim 1, characterized in that the armored or armored wires comprise steel. 6. The well registration cable according to claim 1, characterized in that the armored or armored wires comprise a corrosion resistant alloy. The well registration cable according to claim 1, characterized in that the at least one tube comprises an inner layer, a layer of metallic plate placed on an outer surface of the inner layer, and an outer layer placed in an outer layer. outer surface of the sheet metal layer. 8. The well registration cable according to claim 1, characterized in that the armored or armored wires are placed in a plurality of substantially cylindrical layers that encircle the at least one electrical conductor, and the outer layer has an external diameter substantially the same as an external diameter of the others of the armored or armored wires placed in one of the concentric layers. The well registration cable according to claim 7, characterized in that the inner layer has an internal diameter selected to provide free movement of the optical fiber therein and to provide sufficient compressive strength for the stress loads and lateral, applied to the well log cable.