CN213339733U - Cable suitable for underground environment - Google Patents

Abstract

The utility model discloses a cable suitable for environment in pit, include: a central core structure consisting of a central core (102) and a protective layer (104); a polymer fiber layer (108) configured to provide tensile strength and load bearing capacity to the cable structure; an inner layer (106) formed within the polymer fiber layer 108, the inner layer (106) being capable of inhibiting the ingress of water or gas; an outer layer (110) surrounding the polymer fiber layer (108); and an outer protective sheath (112). The cable is configured to protect internal structures that may be adversely affected by exposure to a downhole environment by at least two protective layers, an inner layer (106) and an outer layer (108). In some examples, the structure to be protected is enclosed in a protective tube within a protective outer sheath. The structure provides strength and load bearing capabilities to structures such as polymer fibers in the cable by protecting the fibers from exposure to gases or liquids in the wellbore.

Description

Cable suitable for underground environment

Technical Field

The utility model relates to a cable suitable for environment in pit can be used to carry the cable of other types of equipment in logging tool and the pit shaft in the oil gas well to and can be used to with the cable that is located the equipment communication in the environment in pit.

Background

For many years, many types of cables have been used to communicate with logging instruments and other equipment located in a downhole environment. The most common of these cables is commonly referred to as "steel cord". These armor layers are also used as cable television cables because they comprise one or more layers of steel wire armor, but in many environments they are heavy and not suitable for incorporation in the field. For example, in many high pressure environments, it is not only difficult, but also potentially environmentally undesirable, to obtain an adequate pressure seal around the wireline. One method of establishing a seal in such high pressure environments involves the high pressure package injecting grease under high pressure to provide the necessary seal between various types of seal packing elements and uneven surfaces of the steel cord. However, such systems can generate a significant amount of friction that resists movement of the cable. In addition, the grease injected often poses an environmental hazard.

Because of these difficulties with cables, cables have been proposed to minimize the problems associated with uneven outer surfaces and also to reduce the weight of the cable. While these proposed cables are believed to have certain advantages over wired cables, they are not perfect for all applications.

In addition, in downhole environments, many corrosive materials (e.g., H)₂S) generally adversely affect its load-bearing capacity. In most conventional cables, the optical fibers are next to the outermost layer. Thus, any damage to the outermost layer will allow corrosive liquids or gases to directly contact the fibers, resulting in potential degradation of the fibers. Any damage to such an outermost layer will typically introduce water into the fibers, further potentially degrading the fibers. It has been proposed to include a layer of PETP tape between the outer layer and the optical fiber; however, such adhesive tape layers are not known to be resistant to problematic permeation by water or corrosive gases or liquids. As a result, conventional synthetic fiber cables provide less than ideal performance in many types of downhole operations.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention provides a cable suitable for use in a downhole environment, the downhole cable configured to protect an internal structure that may be adversely affected by exposure to the downhole environment through at least two protective layers. The structure provides strength and load bearing capabilities to structures such as polymer fibers in the cable by protecting the fibers from exposure to gases or liquids in the wellbore.

Preferably, the structure to be protected will be enclosed in a protective tube within a protective outer sheath.

Preferably, the cable has a tensile strength of at least 4000psi, although greater tensile strength is virtually always desirable.

Preferably, the cable has an outer diameter of 0.300 inch to 0.500 inch.

Preferably, the cable comprises a cylindrical central core, constituted by a communication element capable of carrying data signals, such as an electrical conductor or an optical fibre. If the core is an electrical conductor, it is preferably a metal conductor, and further includes a protective coating.

Drawings

FIG. 1 depicts an example cable utilizing a uniform symmetric single element core structure.

Reference numerals: a cable (100); a central core (102); a protective layer (104); an inner layer (106); a polymer fiber layer (108); an outer layer (110); an outer protective sheath (112).

Detailed Description

The cables described herein are configured to protect internal structures that may be adversely affected by exposure to a downhole environment by at least two protective layers. In this case, polymer fibers and the like structures, including the above-described PBO fibers provided in some downhole cables for strength and load-bearing capacity, are protected from exposure to gas or fluid in the wellbore by at least two different protective layers. Thus, even if the outermost protective layer is damaged, there is an additional protective layer between such polymer fibers and the gas or fluid in the wellbore. This additional protective layer not only protects the optical fibers and other inner layers from gases and other liquids, but also provides abrasion resistance when the outer jacket is damaged. Cables that may benefit from such a structure may include cables having only 1 or 2 data-capable structures, such as electrical conductors or optical fibers; up to cables with more conductors or optical fibers, seven of which are common industry specifications. As illustrated in fig. 1, such a cable may comprise a protective tube surrounding the polymer fiber layer, wherein both are concentric with the central core of the cable; or such polymer fibers or other structures to be protected are distributed in a plurality of separate groupings, each of which is retained within its own protective tube.

Referring in more detail to the drawings, and in particular to fig. 1, there is depicted an exemplary invention of one configuration of a cable 100 according to the present invention. In the depicted embodiment, cable 100 is designed to be uniformly cylindrical. Accordingly, each concentric material layer within cable 100 is intended to have a symmetrical cross-section as shown in fig. 1, within the practical circumstances of conventional manufacturing techniques and the use impact of such cables. Cable 100 includes a central core structure comprised of a central core 102 and a protective layer 104. The cylindrical central core 102 is made up of communication elements capable of carrying data signals, such as electrical conductors or optical fibers. If the central core 102 is an electrical conductor, it is preferably a metal conductor, and also includes a protective coating. An example of such conductors and coatings is a copper conductor coated with a nickel protective layer. If the central core 102 is an optical fiber, it may be desirable to encapsulate the optical fiber in a protective tube.

The protective layer 104 surrounds the central core 102. The protective layer 104 may be formed of any material suitable for use in downhole conditions. In applications where the core includes an electrical conductor, the protective layer is also typically electrically insulating. In some applications, particularly when the central core 102 includes one or more optical fibers, the protective layer 104 is formed of metal, and in some embodiments is provided in the form of a metal jacket as described above around the optical fibers. When the insulating protective layer 104 is required, a layer formed of or at least including a perfluoroalkoxy fluorocarbon is presently preferred. In some cases, other materials, such as polytetrafluoroethylene, may be used. However, in general, the higher capacitance of PTFE can cause problems with data transmission through the carrier, such as where the central core 102 is an electrical conductor. PFA also typically has a higher effective temperature rating, thereby increasing its applicability in downhole cables. PFA is also more crack resistant than PTFE.

The cable 100 comprises concentric layers intended to protect the polymer fiber layer 108, in fact, in a protective tube, formed between an inner layer 106 inside the polymer fiber layer 108 and an outer layer 110 surrounding the polymer fiber layer 108. The inner layer 106 and the outer layer 110 are selected because they can withstand the adverse materials and conditions in the downhole environment and, thus, can protect the polymer fiber layer 108 from potentially damaging materials and conditions. As previously mentioned, when the polymer fiber layer 108 is formed in the PBO fibers, in whole or at least in part, it is important that the inner and outer layers 106, 110 protect the PBO fibers from fluids and gases in the downhole environment even if the outer protective sheath 112 is damaged, and that if the core is designed to eliminate gas, water and corrosive migration, no "water-blocking agents" or liquids need to be added to the inner layer 106. This water-blocking agent is an inert material, such as silicone oil, which will inhibit the ingress of water or gas. Generally, an inert viscous material is one whose viscosity is generally suitable to resist migration under at least some operating conditions. Generally, the viscosity is greater than about 10 Pa-S. Higher viscosities are generally considered as a positive quality for most applications, considered desirable. As noted above, it is desirable to completely soak the PBO or other fibers in the fluid block material so that gases and water cannot migrate to or within the PBO fiber layer.

Additionally, to provide direct electrical circuitry through cable 100, it is preferred that at least one of, or possibly both of, inner layer 106 and outer layer 110 be formed from a solid electrical conductor, such as a metal conductor, including, for example, a suitable solid metal conductor. However, for many corrosive environments, solid metal conductors may not be as advantageous as metal alloys, such as nickel-containing alloys, other possible alternatives being other metal alloys. As yet another alternative, the solid metal or other metal layer may be coated with a protective coating, which may be of one or more types. Examples of suitable coatings include: nickel; powder coatings, such as fluoropolymer coatings, e.g., ethylene-chlorotrifluoroethylene coatings; as well as any other suitable coating that provides the necessary corrosion and temperature resistant coating to protect the conductor in the intended environment. If the outer layer 110 is a metal, it may be used as a final outer protective layer. Or coated and protected with a suitable downhole compatible plastic.

If it is desired that either of the inner layer 106 and the outer layer 110 be other than a metallic material, that layer should be made of a plastic material, such as polyetheretherketone; or another material such as fluorinated ethylene propylene or another high density polypropylene. It is contemplated that the use of polyetheretherketone or a metal layer helps to maintain a uniform and cylindrical appearance of cable 100. Polyetheretherketone has the advantage of being insoluble in water, gases and liquid hydrocarbons. If another material is used, the material is preferably one that is relatively resistant to migration or other permeation by water or gas. One advantage of using non-metallic materials in cable 100 is that weight savings can be realized.

Claims (4)

1. A cable adapted for use in a downhole environment, comprising: the cable includes: a central core structure; a polymer fiber layer (108); an inner layer (106) formed inside the polymer fiber layer 108; an outer layer (110) surrounding the polymer fiber layer (108); and an outer protective sheath (112).

2. A cable suitable for use in a downhole environment according to claim 1, wherein: the central core structure is composed of a central core (102) and a protective layer (104).

3. A cable suitable for use in a downhole environment according to claim 1, wherein: the polymer fiber layer (108) is capable of providing tensile strength and load bearing capacity to the cable.

4. A cable suitable for use in a downhole environment according to claim 1, wherein: the inner layer (106) is capable of inhibiting the ingress of water or gas.

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