HEATING CABLE FOR EXTRACTION PIPES OF VISCOUS HYDROCARBONS OR PARAFFINIC IN CONVENTIONAL WELLS AND TYPE TIGHT WELLS, VERTICAL OR DIRECTIONAL, WITH FLOODED ANNULAR IN CASUAL OR PERMANENT FORM, SUITABLE FOR USE BETWEEN LOW AND HIGH FLUID PRESSURES RANGES

Abstract

A heating cable for an extraction pipe of viscous hydrocarbon or paraffinic in a well, the heating cable including a sleeve made of a flexible material, the sleeve has a perimeter, an internal cavity, and a continuous homogeneous length, the sleeve is free of perforations; electrically conductive conductors placed inside the sleeve, the electrically conductive conductors are parallel to each other and separate from each other by a space; a primary insulation layer independently wrapping each one of the electrically conductive conductors; a layer including of a single fluoropolymer material completely filling up the entire cavity of the sleeve and forming a solid structure that encases the electrically conductive conductors, the primary insulation layer, the entire space between the electrically conductive conductors, and the entire perimeter of the sleeve; a metallic shield surrounding the layer consisting of the single monolithic fluoropolymer material, the metallic shield has a shape of a ribbon; the heating cable is flat.

Description

REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation in part Application of U.S. application Ser. No. 15/700,137, filed Sep. 10, 2017, entitled HEATING CABLE FOR EXTRACTION PIPES OF VISCOUS HYDROCARBONS OR PARAFFINIC IN CONVENTIONAL WELLS AND TIGHT TYPE WELLS, VERTICAL OR DIRECTIONAL, WITH FLOODED ANNULAR IN CASUAL OR PERMANENT FORM, SUITABLE FOR USE BETWEEN LOW AND HIGH FLUID PRESSURE RANGES, pending, which is a continuation of U.S. application Ser. No. 14/249,847 filed Apr. 10, 2014, entitled, HEATING CABLE FOR EXTRACTION PIPES OF VISCOUS HYDROCARBONS OR PARAFFINIC IN CONVENTIONAL WELLS AND TIGHT TYPE WELLS, VERTICAL OR DIRECTIONAL, WITH FLOODED ANNULAR IN CASUAL OR PERMANENT FORM, SUITABLE FOR USE BETWEEN LOW AND HIGH FLUID PRESSURE RANGES, abandoned, the content of which is incorporated herein by reference, which claimed priority over Argentinean Application No. 20130101184, filed Apr. 12, 2013.

FIELD OF THE INVENTION

[0002] The present invention relates to a heating cable for extraction pipes of viscous hydrocarbon or paraffinic in conventional wells and tight type wells, vertical or directional, with flooded annular in eventual or permanent cases, suitable for use between low and high fluid pressure ranges, the cable being flat with parallel electric conductors, with high operational flexibility.

[0003] The purpose of this heating type cable is to avoid and/or unblock obstructions in extraction well pipes for hydrocarbons caused by the accumulation of substances, such as paraffin and hydrates, as well as to reduce the high oil viscosity rates, hindering the fluid removal, especially when this fluid is at the lower paraffin viscosity or precipitation temperature values, lower than the suitable limit values, and exposed to high pressure, for example, over a 1000 psi and reaching more than even the 10,000 psi.

BACKGROUND OF THE INVENTION

[0004] The prior art shows a special heating cable in which the heating effect is achieved by a short circuit between the core and one of the surface layers.

[0005] In addition, the prior art shows a heating cable which includes fiber optic conductors. The fiber optic allows measuring the well's temperature; and therefore, it is also used to detect fluid presence by the temperature difference.

[0006] Also, the prior art shows a heating cable whose structure is predominantly made of lead, intended to the three-phase power supply which is applied directly on the pipe. In the practice, this type of cable has resulted in numerous faults, only tolerated low heating powers and required very high currents, therefore they are not suitable for oil production pipes of high viscosity or pressure.

[0007] The prior art shows a heater that is fixed onto the concrete walls of non-intubated wells.

[0008] In addition, the prior art shows a heat pump, which heats the intake making a short circuit between the pumping tree and the wall of the tube production.

[0009] Finally, the prior art shows a heating cable for oil production pipes characterized because it includes the combination of a thermo conductive metal outer pipe and inner flexible cover with electrically insulating properties, anti-corrosive and mechanical strength properties, wherein the cover is formed by a plurality of overlapped layers which includes: (a) first an electrically insulating inner layer which surrounds the power electrical wires for the heater elements connected to the conductor along the device; (b) a second enmeshing metallic layer that surrounds the first layer; (c) a third polymeric layer that surrounds the second layer; and (d) an outer shielding layer, which surrounds the third layer. Although this heating cable, under certain conditions, properly meets its function, when it is subjected to high pressures inside of the hydrocarbon production well, begins to have structural and functional deficiencies. It is to say, through the interstices of the metallic mesh, the high pressure causes deformation in the insulating layer that surrounds the electrical conductors, thus affecting the dielectric capacity of the insulation layer, which results even more noticeably by the chemical effects of the fluid that is filtered between the mesh and the insulating layer. In addition, the metallic mesh is permeable to the radio frequencies, which, due to their own flow current can generate interference on other cables or instruments used in the well.

[0010] With the current state of technology, it is common that the wells are brought to exploitation limits that were before impossible, and is usual that the wells are of high pressure, for example, the tight type of wells of recent development in the world. All of this leads to all accessories and elements used in the extraction should be more resilient, so it is essential that the development of new elements is highly resistant to high pressure and temperatures, as is the cable that is the object of the present invention.

Advantages of the Invention

[0011] In the heating cable of the present invention, the number of layers that define its structure with regard to the succession of layers of the conventional cables has been reduced, allowing to simplify the manufacturing process, lowering the time than the standard time involved, and reducing the electric energy consumption of the required materials or supplies, all of which translates into lower cable manufacturing cost.

[0012] Regarding the advantages in the use of this cable, it is worth mentioning, for example, that it is extremely suitable to withstand high pressure and temperatures without risk of leakage between the layers that could damage its structure, such as is the case in conventional cables, thus, increasing the cable service life, and maintaining the electrical conductors insulated efficiently and protected even in the presence of very high fluid pressure.

[0013] In the present invention the term "monolithic layer" means a solid layer made of a single strong material.

[0014] The structure of the monolithic (solid) layer of the fluoropolymer materials gives the cable a great mechanical resistance to the compression and, at the same time, a high dielectric coefficient without fissures, which gives a high reliability and a wider range of operation. Also, these structural features provide a greater resistance to reinstallation operations arising from "pulling" operations, usually in wells and particularly critical in horizontal or directional wells by high mechanical exposure of them.

[0015] The particular design of this invention makes it small enough to enter in very tight tubing--casing combinations that no other systems in the industry can do. Also require lower currents for high power which make the application easier to feed with standard field power sources. It is particularly suited to new high-pressure wells that use those combinations like Non-Conventional wells Tight or Shale. It is also very useful when used in "in liner" installations in horizontal or deviated wells, no matter if they are Conventional or Non-Conventional. The liner is smaller than the casing and in general the space available to install anything inside a liner is very limited. The small section required to install this heater makes it the best option when liners are small (from 5'' to 7'') without compromising oil flow or power output.

[0016] The particular structure of the heater makes it also very simple to modify, adapt or repair, thereby maintaining the low profile and also its operational safety.

SUMMARY OF THE INVENTION

[0017] It is an object of the present invention to provide a heating cable for extraction pipes of viscous hydrocarbon or paraffinic in conventional wells and tight type wells, vertical or directional, with flooded ring in eventual or permanent cases, suitable for use between low and high fluid pressure ranges. This cable, of flat type with parallel electric conductors, is also suitable for use in both vertical and directional wells, with high operational flexibility in a wide range of variables. Each one of the electric conductors is covered by a primary insulation layer, and the assembly thereof is monolithically coated by a main insulating layer of fluoropolymer material resistant to the high pressure of the surrounding fluid. Outside of the main insulating layer, the cable structure is complemented with an external shield defined by a thin layer of metallic material.

[0018] The invention relates to a heating cable for an extraction pipe of viscous hydrocarbon or paraffinic in a well, the heating cable including a sleeve made of a flexible material, the sleeve has a perimeter, an internal cavity, and a continuous homogeneous length, the sleeve is free of perforations; electrically conductive conductors placed inside the sleeve, the electrically conductive conductors are parallel to each other and separate from each other by a space; a primary insulation layer independently wrapping each one of the electrically conductive conductors; a layer including a single fluoropolymer material completely filling up the entire cavity of the sleeve and forming a solid structure that encases the electrically conductive conductors, the primary insulation layer, the entire space between the electrically conductive conductors, and the entire perimeter of the sleeve; a metallic shield surrounding the layer consisting of the single monolithic fluoropolymer material, the metallic shield has a shape of a ribbon; the heating cable is flat.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For greater clarity and understanding of the present invention, it is illustrated in several figures where it is represented according to the preferred embodiments, for example, where:

[0020] FIG. 1 is a cross-sectional view of the heating cable;

[0021] FIG. 2 is a partial cross-sectional perspective view of a section of the heating cable;

[0022] FIG. 3 shows, as an example of application of the heating cable, a section of the hydrocarbons extraction pipe on which are fixed the thermo conductive conductors in which interior extends the cable; and

[0023] FIG. 4 shows a cross sectional view showing the thermo conductive conduits attached to a rod located in the interior of the production pipe.

DETAILED DESCRIPTION OF THE INVENTION

[0024] In FIGS. 1 and 2 can be seen that the heating cable 1 object of the present invention. The heating cable 1 is flat and includes:

[0025] A sleeve 1a made of a flexible material. The sleeve 1a has a perimeter, an internal cavity, and a continuous homogeneous length. The sleeve 1a is solid and free of perforations.

[0026] Electrically conductive conductors 2 are placed inside the sleeve 1a. The electrically conductive conductors 2 are parallel to each other and separated by a space.

[0027] A primary insulation layer (3) independently wraps each one of the electrically conductive conductors 2.

[0028] Each conductor will be individually protected in order to increase the operational safety.

[0029] The insulating layer consisting of a single element insulating material needs to be flexible yet very resistant to outer pressure (crushing) and at the same time maintain an extremely high dielectric value. This consideration is based on the fact that such layer is thin and will be exposed to pressure, high temperatures, and eventually to aggressive chemicals if the outer layer is damaged. In such case, It will act as a second barrier of defense and will maintain the heater in operation until a pulling activity may allow to repair it.

[0030] Using a single material makes it simpler and fulfills the required characteristics. Using different layers of different materials may seem better but that adds a complexity that in the end goes against the final objective. A failure probability increases whit the use of more layers. In general, several layers are used when you cannot achieve the different characteristics with only one. For example, adding a metal clad to increase mechanical resistance. (That is not needed in the presented design)

[0031] That increases failure probability, increases size (which is critical as explained in uses with tight spaces) and also increases cost and complicates or voids repair possibilities.

[0032] A layer consisting of a single fluoropolymer material (4) completely fills up the entire cavity of the sleeve 1a and forms a solid structure (monolithically) that encases the electrically conductive conductors 2, the primary insulation layer (3), the entire space between the electrically conductive conductors 2, and the entire perimeter of the sleeve 1a.

[0033] The single fluoropolymer material (4) is resistant to the high pressure of the surrounding fluid.

[0034] Filling completely the entire cavity of the sleeve 1a with the single fluoropolymer material (4) provides a solid structure having the electrically conductive conductors 2 that gives the heating cable a great mechanical resistance to the compression and, at the same time, a high dielectric coefficient without fissures, which gives a high reliability and a wider range of operation.

[0035] Different fluoropolymers may be but not all of them are suitable to fulfill all requested variables. For example, Polytetrafluoroethylene (PTFE) can withstand higher temperatures but it is not hard enough for the application. Others may cover one of the required characteristics but not all of them at the same time.

[0036] One of the preferable fluoropolymers may be Ethylene tetrafluoroethylene (ETFE). The ETFE provides the necessary strength while maintaining a high dielectric insulation and excellent chemical resistance.

[0037] In one embodiment, the present invention uses Polyether ether ketone (PEEK). The PEEK is a non-fluorinated polymer option that will be technically suitable, but cost it is considerably higher.

[0038] An external shield (5) is placed outside the solid layer (4). The external shield (5) is made of a thin layer of a metallic material. The external shield (5) may be, for example, in the form of a ribbon wound around the fluoropolymer material (4).

[0039] On the example of the preferred embodiment, which is described and illustrated, the electrical conductors 2 are multifilament conductors.

[0040] In another preferred embodiment, the cable 1 includes three lines of conductors 2 which correspond to each one of the phases of the three-phase power applied.

[0041] FIG. 3 shows a typical hydrocarbons extraction pipe 6 which is placed in a production well, on which are fixed, heat exchangers and thermo conductive metallic conduits 7, through support devices having anchors 8 and clamps 9. Throughout the conduits 7, the heating cable 1 of the present invention is extended.

[0042] FIG. 4 shows an alternative use of the cable 1, in the practice, the thermo conductive conduits 7 can be attached, for example, to a rod 10 located in the interior of the production pipe 6 in position substantially coaxial with the mounting and fastening devices (8,9). In this way, the thermo conductive conduits 7 with the cable 1 inside, will define a direct heat exchange medium with the fluid transported by the production pipe, it is worthy to say that without the duct 5 being in contact with the inner wall of the production pipe, but directly with the circulating fluid within it.

[0043] The heating cable may include a flexible sleeve; and

[0044] a solid core placed inside the flexible sleeve;

[0045] the solid core includes solid layer consisting of a single fluoropolymer material and encasing a plurality of electrically conductive conductors that are individually wrapped with a primary insulation layer and a metallic shield surrounding the layer consisting of the single monolithic fluoropolymer material;

[0046] wherein the electrically conductive conductors are parallel to each other and separate from each other by a space.

[0047] Having thus particularly described and determined the nature of the present invention and how it is to be realized, is claimed, in exclusive the right and property.

Claims

1. A heating cable for an extraction pipe of viscous hydrocarbon or paraffinic in a well, the heating cable comprising: a sleeve made of a flexible material, the sleeve has a perimeter, an internal cavity, and a continuous homogeneous length, the sleeve is free of perforations; electrically conductive conductors placed inside the sleeve, the electrically conductive conductors are parallel to each other and separate from each other by a space; a primary insulation layer independently wrapping each one of the electrically conductive conductors; a layer consisting of a single fluoropolymer material completely filling up the entire cavity of the sleeve and forming a solid structure that encases the electrically conductive conductors, the primary insulation layer, the entire space between the electrically conductive conductors, and the entire perimeter of the sleeve; a metallic shield surrounding the layer consisting of the single fluoropolymer material, the metallic shield has a shape of a ribbon; wherein the heating cable is flat.

2. The heating cable comprising: a flexible sleeve; and a solid core placed inside the flexible sleeve; wherein the solid core includes solid layer consisting of a single fluoropolymer material and encasing a plurality of electrically conductive conductors that are individually wrapped with a primary insulation layer and a metallic shield surrounding the layer consisting of the single monolithic fluoropolymer material; wherein the electrically conductive conductors are parallel to each other and separate from each other by a space.

3. A heating cable for an extraction pipe of viscous hydrocarbon or paraffinic in a well, the heating cable comprising: a thermo conductive conduit; and a heating cable including: a sleeve made of a flexible material, the sleeve has a perimeter, an internal cavity, and a continuous homogeneous length, the sleeve is free of perforations; electrically conductive conductors placed inside the sleeve, the electrically conductive conductors are parallel to each other and separate from each other by a space, a primary insulation layer independently wrapping each one of the electrically conductive conductors, a layer consisting of a single fluoropolymer material completely filling up the entire cavity of the sleeve and forming a solid structure that encases the electrically conductive conductors, the primary insulation layer, the entire space between the electrically conductive conductors, and the entire perimeter of the sleeve, a metallic shield surrounding the layer consisting of the single fluoropolymer material, the metallic shield has a shape of a ribbon, wherein the heating cable is flat; wherein the flat cable passes through the thermo conductive conduit; wherein the thermo conductive conduit secured to a rod located inside an extraction pipe; wherein the rod and the thermo conductive conduit are not in contact with inner walls of the extraction pipe, but in direct contact with the fluid transported inside the extraction pipe.