Umbilical and method of perforating an umbilical

Abstract

The present application relates to the technical field of submarine cable, and especially relates to a kind of umbilical cable and umbilical cable punching method.The umbilical cable includes: inner sheath, inner layer functional unit group, outer sheath, outer layer functional unit group and armored layer.Inner layer functional unit group is arranged in inner sheath, outer layer functional unit group is arranged between inner sheath and outer sheath, armored layer includes armored sheath and metal armor, metal armor is arranged between armored sheath and outer sheath;Multiple first water inlets are arranged in outer sheath along the length direction, and multiple second water inlets are arranged in armored sheath along the length direction.The umbilical cable provided by the present application can make seawater enter the space where outer layer functional unit group is located through second water inlet and first water inlet in sequence by arranging multiple first water inlets on outer sheath and multiple second water inlets on armored sheath along the length direction, and can reduce the friction torque between outer layer functional unit group and outer sheath under the action of seawater, to avoid torque accumulation causing birdcage accident.

Description

Technical Field

[0001] This invention relates to the field of submarine cable technology, and in particular to an umbilical cable and a method for drilling holes in the umbilical cable. Background Technology

[0002] The steel tube-type electro-hydraulic composite umbilical cable for underwater production systems is a key component of underwater production systems, especially deep-water production systems. Its main function is to provide electro-hydraulic power and chemical injection channels for underwater production systems, while also providing data transmission channels for control signals from the upper modules and the underwater production system.

[0003] Traditional deep-sea umbilical cables typically consist of functional unit groups and an outer sheath enclosing these units. However, due to the unique operating environment of deep-sea umbilical cables, they are prone to bending and swaying under ocean currents. This results in significant frictional torque between the functional units and the outer sheath. Accumulated torque can lead to birdcage damage. A birdcage damage refers to damage occurring in the cable's armor layer or functional units due to excessive twisting or bending, causing localized fractures or deformations in the armor layer and creating a birdcage-like structure. This damage exposes the cable's internal structure, potentially leading to cable malfunction, insulation failure, or other faults. Summary of the Invention

[0004] This invention provides an umbilical cable and a method for drilling holes in the umbilical cable, in order to solve the defect of existing deep-sea umbilical cables that are prone to causing birdcage accidents.

[0005] The present invention provides an umbilical cable, comprising: an inner sheath, an inner functional unit group, an outer sheath, an outer functional unit group, and an armor layer.

[0006] The inner functional unit group is disposed within the inner sheath, and the outer functional unit group is disposed between the inner sheath and the outer sheath. The armor layer includes an armor sheath and metal armor, and the metal armor is disposed between the armor sheath and the outer sheath. The outer sheath is provided with a plurality of first water inlets spaced apart along the length direction, and the armor sheath is provided with a plurality of second water inlets spaced apart along the length direction.

[0007] According to the umbilical cable provided by the present invention, the spacing between adjacent first water inlets is 50m to 150m, and the spacing between adjacent second water inlets is 50m to 150m.

[0008] According to the umbilical cable provided by the present invention, the inner functional unit group includes a plurality of first steel tube units evenly distributed circumferentially within the inner sheath, and a second steel tube unit filling the spaces between adjacent first steel tube units; the outer functional unit group includes a plurality of electrical units spaced circumferentially, the plurality of electrical units dividing the area between the inner sheath and the outer sheath into a plurality of installation spaces, and at least one third steel tube unit is provided in each installation space.

[0009] According to the umbilical cable provided by the present invention, the inner functional unit group includes three first steel pipe units distributed in an equilateral triangle, and a second steel pipe unit is provided between adjacent first steel pipe units, wherein the diameter of the first steel pipe unit is larger than the diameter of the second steel pipe unit.

[0010] And / or, the outer functional unit group includes four electrical units spaced apart circumferentially, the four electrical units dividing the area between the inner sheath and the outer sheath into two first mounting spaces and two second mounting spaces, the two first mounting spaces being arranged opposite each other, the two second mounting spaces being arranged opposite each other, three third steel pipe units being arranged adjacently in the first mounting space, and one fourth steel pipe unit being arranged in the second mounting space.

[0011] According to the umbilical cable provided by the present invention, two first fillers are further provided in the first installation space. The outer side of the first filler is fitted with the outer sheath. The inner side of one of the first fillers is fitted with the third steel pipe unit located at the first end of the first installation space, and the inner side of the other first filler is fitted with the third steel pipe unit located at the second end of the first installation space. The first end of the first filler abuts against the corresponding electrical unit, and the second end of the first filler abuts against the third steel pipe unit located in the middle.

[0012] According to the umbilical cable provided by the present invention, two second fillers are further provided in the second installation space. The outer side of the second filler is attached to the inner surface of the outer sheath, the inner side of the second filler is attached to the outer surface of the inner sheath, the first end of the second filler is attached to the corresponding electrical unit, and the second end of the second filler is attached to the fourth steel pipe unit.

[0013] According to the umbilical cable provided by the present invention, an optical unit for detecting the degree of bending of the umbilical cable is further provided between the second filler and the outer sheath, and at least one deformation channel is provided in the second filler.

[0014] Another aspect of the present invention provides a method for drilling holes in an umbilical cable, comprising the following steps.

[0015] Obtain the material and thickness data of the sheath, and determine the allowable tear stress of the sheath based on the material and thickness data of the sheath.

[0016] One end of the umbilical cable is lowered into the water at a speed of V, causing an air column of length L to form inside the sheath.

[0017] Based on the descent speed V of the umbilical cable and the length L of the air column inside the umbilical cable, the internal pressure P1 at the top of the air column is determined.

[0018] Based on the internal pressure P1 at the top of the air column, the circumferential stresses on the inner and outer surfaces of the sheath are determined. .

[0019] The circumferential stress on the inner and outer surfaces of the sheath The perforation spacing of the water inlet holes on the sheath is determined by comparing the perforation with the allowable tear stress of the sheath and based on the comparison results.

[0020] According to the umbilical cable drilling method provided by the present invention, the internal pressure P1 at the top of the air column satisfies the following formula.

[0021] ;

[0022] in, γ = , air density, This refers to the density of seawater.

[0023] According to the umbilical cable drilling method provided by the present invention, the circumferential stress The following expression is satisfied.

[0024] ;

[0025] =- ;

[0026] ;

[0027] ;

[0028] in, The radial stress of the sheath, The inner diameter of the sheath is [missing information]. The outer diameter of the sheath. The radius value is used in the formula for calculating coefficients A and B.

[0029] The umbilical cable provided by the present invention has multiple first water inlets spaced apart on the outer sheath and multiple second water inlets spaced apart along the length of the armor sheath. Seawater can enter the space where the outer functional unit group is located through the second water inlets and the first water inlets in sequence. Under the action of seawater, the frictional torque between the outer functional unit group and the outer sheath can be reduced, avoiding the accumulation of torque that could cause birdcage accidents.

[0030] The umbilical cable perforation method provided by this invention can determine the minimum spacing of perforations on the sheath according to the material and thickness of the sheath, preventing the umbilical cable from being squeezed and burst by internal pressure during the lowering process.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a cross-sectional schematic diagram of the umbilical cable provided in an embodiment of the present invention.

[0034] Figure 2 This is a flowchart illustrating the umbilical cable perforation method provided in an embodiment of the present invention.

[0035] Figure 3 This is a schematic diagram of step S220 in the umbilical cable punching method provided in the embodiment of the present invention.

[0036] Figure 4 This is one of the force analysis diagrams of the sheath in the umbilical cable punching method provided in the embodiments of the present invention.

[0037] Figure 5 This is the second stress analysis diagram of the sheath in the umbilical cable perforation method provided in the embodiments of the present invention.

[0038] Figure label:

[0039] 10. Inner sheath; 110. Inner functional unit group; 111. First steel pipe unit; 112. Second steel pipe unit; 20. Outer sheath; 210. Outer functional unit group; 211. Electrical unit; 212. Third steel pipe unit; 213. Fourth steel pipe unit; 214. First filler; 215. Second filler; 216. Optical unit; 30. Armor layer; 310. Armor sheath; 320. Metal armor. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0041] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0043] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] The following is combined Figures 1 to 5 This invention describes the umbilical cable and the umbilical cable drilling method provided by the present invention.

[0046] See Figure 1 As shown, the umbilical cable provided in this embodiment of the invention includes: an inner sheath 10, an inner functional unit group 110, an outer sheath 20, an outer functional unit group 210, and an armor layer 30.

[0047] The inner functional unit group 110 is located inside the inner sheath 10, and the outer functional unit group 210 is located between the inner sheath 10 and the outer sheath 20. The armor layer 30 includes an armor sheath 310 and a metal armor 320, with the metal armor 320 located between the armor sheath 310 and the outer sheath 20. The outer sheath 20 is provided with a plurality of first water inlets at intervals along its length, and the armor sheath 310 is provided with a plurality of second water inlets at intervals along its length.

[0048] The umbilical cable provided by the present invention has multiple first water inlets spaced apart on the outer sheath 20 and multiple second water inlets spaced apart along the length direction on the armor sheath 310. Seawater can enter the space where the outer functional unit group 210 is located through the second water inlets and the first water inlets in sequence. Under the action of seawater, the frictional torque between the outer functional unit group 210 and the outer sheath 20 can be reduced, avoiding the accumulation of torque that could cause birdcage accidents.

[0049] Specifically, the outer sheath 20 is provided with a plurality of first water inlets at intervals along its length. These first water inlets can be evenly spaced, for example, with a spacing of 100 mm between adjacent first water inlets. Alternatively, the first water inlets can be spaced non-uniformly, for example, with a spacing between 50 mm and 150 mm between adjacent first water inlets. Similarly, a plurality of second water inlets can be evenly spaced, for example, with a spacing of 100 mm between adjacent second water inlets. Again, the plurality of second water inlets can be spaced non-uniformly, for example, with a spacing between 50 mm and 150 mm between adjacent second water inlets.

[0050] It should be noted that the distance between adjacent first / second water inlets is the center-to-center distance between the holes. For example, when the first / second water inlet is a circular hole, the distance between adjacent first / second water inlets is the center-to-center distance.

[0051] The first and second water inlets can be in the shape of regular shapes such as circles, triangles, and squares, or other irregular shapes. This invention does not impose any specific limitations on this.

[0052] Both the inner functional unit group 110 and the outer sheath 20 functional unit group can include steel pipe units, electrical units 211, optical units 216, and fillers, etc.

[0053] The steel pipe unit is used to provide a gas or liquid transport channel for the underwater production system. For example, gaseous or liquid fuels or chemical agents can be transported to the underwater production system through the steel pipe unit.

[0054] Electrical unit 211 is used to provide power or electrical signals to the underwater production system.

[0055] Optical unit 216 is used to detect the bending deformation of the umbilical cable. The fiber optic sensor in optical unit 216 senses the changes in optical signals caused by bending. Specifically, when the umbilical cable bends, the refractive index and optical path of the fiber change, thereby affecting the transmission and intensity of the optical signal. These changes can be detected and analyzed to monitor and assess the degree of bending and potential damage to the umbilical cable, and to detect the location of bending and damage.

[0056] The filler is used to secure functional units such as the steel tube unit, electrical unit 211, and optical unit 216 within the internal structure of the umbilical cable, helping to maintain the relative positions of these units and preventing them from moving when the umbilical cable is bent or subjected to stress. The filler prevents displacement of the functional units within the umbilical cable, thereby reducing the risk of damage caused by vibration, impact, or external pressure. Furthermore, the filler helps maintain the overall structural stability and shape consistency of the umbilical cable, ensuring its mechanical strength and durability during operation.

[0057] It should be noted that both the inner functional unit group 110 and the outer sheath 20 functional unit group may include at least one of the following: a steel pipe unit, an electrical unit 211, and an optical unit 216, and may or may not include filler. The number of steel pipe units, electrical units 211, and optical units 216 in the inner functional unit group 110 and the outer sheath 20 functional unit group can be single or multiple, depending on the specifications of the umbilical cable and specific usage requirements; this invention does not impose specific limitations in this regard.

[0058] The armor layer 30 provides mechanical protection for the functional units of the umbilical cable. It includes a metal armor 320 and an armor sheath 310. The metal armor 320 is fitted onto the outer sheath 20, and the armor sheath 310 is fitted onto the metal armor 320. The metal armor 320 typically consists of multiple metal wires tightly wound around the outer sheath 20 and working in conjunction with the armor sheath 310 to form the armor layer 30.

[0059] According to some embodiments of the present invention, the spacing between adjacent first water inlets is 50m to 150m, and the spacing between adjacent second water inlets is 50m to 150m. By setting the spacing between the first and second water inlets to 50m to 150m, it can be ensured that seawater can enter the umbilical cable through water inlets at different locations, and it can also prevent the sheath from being torn by internal pressure during the process of lowering the umbilical cable into the sea.

[0060] Specifically, the sheath (including the outer sheath 20 and the armor sheath 310) is typically made of HDPE (High-Density Polyethylene) material, with a thickness usually between 3mm and 10mm (e.g., 5mm). During the umbilical cable lowering process, an air column is generated within the sheath, which exerts internal pressure and circumferential stress on the sheath. When the circumferential stress exceeds the allowable tear stress of the sheath, the sheath will rupture. In this embodiment, by setting the spacing between the first water inlet and the second water inlet to 50m to 150m, it can be ensured that the circumferential stress exerted by the air column within the sheath during the umbilical cable lowering process is within the allowable tear stress, preventing damage to the sheath.

[0061] See Figure 1 and Figure 2As shown, according to some embodiments of the present invention, the inner functional unit group 110 includes a plurality of first steel pipe units 111 evenly distributed circumferentially within the inner sheath 10, and second steel pipe units 112 filling the spaces between adjacent first steel pipe units 111; the outer functional unit group 210 includes a plurality of electrical units 211 spaced circumferentially, the plurality of electrical units 211 dividing the area between the inner sheath 10 and the outer sheath 20 into a plurality of installation spaces, each installation space containing at least one third steel pipe unit 212. With the above arrangement, the plurality of first steel pipe units 111 arranged circumferentially in the inner layer and the second steel pipe units 112 filling the spaces between adjacent first steel pipe units 111 can provide multiple gas or liquid transmission channels. Simultaneously, a stable support structure can be formed in the inner layer of the umbilical cable, providing stable support for the outer functional unit group 210. The electrical units 211 dividing the area between the inner sheath 10 and the outer sheath 20 into multiple installation spaces helps to organize and protect the internal functional units and reduce interference. Meanwhile, the third steel pipe unit 212 forms an additional protective layer on the outer layer of the umbilical cable, enhancing the protection of internal components and thus improving the cable's durability and service life.

[0062] See Figure 1 As shown, according to some embodiments of the present invention, the inner functional unit group 110 includes three first steel pipe units 111 arranged in an equilateral triangle. Figure 1 (Numbered 1, 2, 3), a second steel pipe unit 112 is provided between adjacent first steel pipe units 111 ( Figure 1 (Numbers 4, 5, and 6 in the middle) The diameter of the first steel pipe unit 111 is larger than the diameter of the second steel pipe unit 112. By limiting the size and number of the first steel pipe unit 111 and the second steel pipe unit 112, the three first steel pipe units 111 arranged in an equilateral triangle can be fixed to each other, and the second steel pipe unit 112 can be fixed by adjacent first steel pipe units 111. At the same time, the outer sides of the first steel pipe unit 111 and the second steel pipe unit 112 can abut against the inner sheath 10, so that the first steel pipe units 111 and the second steel pipe unit 112 located in the inner layer can remain stable.

[0063] Specifically, in this embodiment, the diameter of the first steel pipe unit 111 is twice the diameter of the second steel pipe unit 112.

[0064] See Figure 1 As shown, according to some embodiments of the present invention, the outer functional unit group 210 includes four electrical units 211 arranged circumferentially. The four electrical units 211 divide the area between the inner sheath 10 and the outer sheath 20 into two first mounting spaces and two second mounting spaces. The two first mounting spaces are arranged opposite to each other, and the two second mounting spaces are arranged opposite to each other. Three third steel pipe units 212 are adjacent to each other in the first mounting space. Figure 1(Numbers 7, 8, 9, 10, 11, 12) A fourth steel pipe unit 213 is located within the second installation space. Figure 1 (Nos. 11 and 12). By dividing the area into multiple installation spaces, the utilization of internal space and component organization are optimized, while the configuration of four electrical units 211 and multiple steel pipe units enhances the mechanical strength and stability of the cable.

[0065] See Figure 1 As shown, according to some embodiments of the present invention, two first filler members 214 are further provided in the first installation space. The outer side of the first filler member 214 is fitted with the outer sheath 20, the inner side of one first filler member 214 is fitted with the third steel pipe unit 212 located at the first end of the first installation space, and the inner side of the other first filler member 214 is fitted with the third steel pipe unit 212 located at the second end of the first installation space. The first end of the first filler member 214 abuts against the corresponding electrical unit 211, and the second end of the first filler member 214 abuts against the third steel pipe unit 212 located in the middle. By providing two first filler members 214 in the first installation space, the gap between the third steel pipe unit 212 and the outer sheath 20 can be filled, providing stable support for the three third steel pipe units 212 simultaneously and preventing the third steel pipe units 212 from slipping.

[0066] It should be noted that the "first end of the first filler 214" specifically refers to the end of the first filler 214 that is close to the adjacent point unit, and the "second end of the first filler 214" specifically refers to the end of the first filler 214 that is far away from the adjacent point unit.

[0067] See Figure 1 As shown, according to some embodiments of the present invention, two second filler members 215 are further provided in the second installation space. The outer side of the second filler member 215 is attached to the inner surface of the outer sheath 20, the inner side of the second filler member 215 is attached to the outer surface of the inner sheath 10, the first end of the second filler member 215 is attached to the corresponding electrical unit 211, and the second end of the second filler member 215 is attached to the fourth steel pipe unit 213. The provision of the second filler member 215 can fill the gap between the inner sheath 10 and the outer sheath 20, providing additional support for the fourth steel pipe unit 213 and enhancing the stability of the overall structure. At the same time, by providing two second filler members 215 in the second installation space, the fourth steel pipe unit 213 can be limited and fixed by the second filler members 215, ensuring its stability.

[0068] See Figure 1As shown in some embodiments of the present invention, an optical unit 216 for detecting the degree of bending of the umbilical cable is further provided between the second filler 215 and the outer sheath 20. The second filler 215 contains at least one deformation channel. By providing the optical unit 216, the bending and damage locations of the umbilical cable can be detected. The at least one deformation channel in the second filler 215 allows deformation during bending and high-load tension of the umbilical cable. A slippage tendency exists between the optical unit 216 and the outer sheath 20, allowing the optical unit 216 to adjust its own strain and reduce damage accumulation.

[0069] Specifically, the fiber optic sensor in optical unit 216 senses changes in the optical signal caused by bending. When the umbilical cable bends, the refractive index and optical path of the fiber change, thus affecting the transmission and intensity of the optical signal. These changes can be detected and analyzed to monitor and assess the degree of bending and potential damage to the umbilical cable, and to detect the location of bending and damage.

[0070] The umbilical cable punching method provided by the present invention is described below. The umbilical cable punching method described below can be referred to in correspondence with the umbilical cable described above.

[0071] See Figure 2 As shown, the umbilical cable punching method provided in this embodiment of the invention includes the following steps.

[0072] S210. Obtain the material data and thickness data of the sheath, and determine the allowable tear stress of the sheath based on the material data and thickness data of the sheath.

[0073] S220. Lower one end of the umbilical cable into the water at a speed of V, so that an air column of length L is formed inside the sheath (which can be regarded as the opening distance of the sheath being L).

[0074] S230. Based on the umbilical cable lowering speed V and the length L of the air column inside the umbilical cable, determine the internal pressure P1 at the top of the air column.

[0075] S240. Based on the internal pressure P1 at the top of the air column, determine the circumferential stress on the inner and outer surfaces of the sheath. .

[0076] S250, circumferential stress on the inner and outer surfaces of the sheath. The perforation spacing of the water inlet holes on the sheath was determined by comparing the perforation with the allowable tear stress of the sheath and based on the comparison results.

[0077] The umbilical cable perforation method provided by this invention can determine the minimum spacing of perforations on the sheath according to the material and thickness of the sheath, preventing the umbilical cable from being squeezed and burst by internal pressure during the lowering process.

[0078] Specifically, in step S210, after obtaining the material and thickness data of the sheath, the initial value of the allowable tear stress of the sheath can be obtained. The final value of the allowable tear stress is usually calculated using the allowable factor k. For example, if the outer sheath uses 5mm thick HDPE material, the initial allowable tear stress is 26MPa. Using the allowable factor k=0.67, the final allowable tear stress is 17.42MPa. Step S220 can be found... Figure 3 As shown.

[0079] See Figures 3 to 5 As shown, according to some embodiments of the present invention, the internal pressure P1 at the top of the air column satisfies the following formula.

[0080] ;

[0081] in, γ = , air density, This refers to the density of seawater.

[0082] Specifically, based on water depth L and the speed of deployment V The internal pressure at the top of the air column can be calculated. At this point, the top of the air column is considered to have no external pressure. As the air column grows and the descent speed increases, the sheath experiences internal pressure... There is a risk of the sheath bursting under pressure; therefore, it is necessary to control the minimum perforation spacing of the sheath to prevent it from being crushed by internal pressure during lowering. It's bursting at the seams.

[0083] See Figures 3 to 5 As shown, according to some embodiments of the present invention, circumferential stress The following expression is satisfied.

[0084] ;

[0085] ;

[0086] ;

[0087] ;

[0088] in, For the radial stress of the sheath, The inner diameter of the sheath. The outer diameter of the sheath. The radius value is used in the formula for calculating coefficients A and B.

[0089] when = or When, radial stress The values ​​of are shown in the following formula, which is used to analyze the limit values. For example, when = hour, =- ,when = hour, .

[0090] Specifically, the internal pressure experienced by the sheath Can be considered as negative radial stress The circumferential stress on the sheath can be calculated using the above formula. Then calculate the circumferential stress. By comparing the allowable tear stress value with that of the sheath, the opening distance of the water inlet holes on the sheath can be adjusted to prevent the sheath from bursting.

[0091] Taking a high-density polyethylene outer sheath umbilical cable with an outer diameter of 232mm and a thickness of 5mm as an example, after the above calculation process, the minimum drilling spacing of the water inlet holes on the sheath is 76m. Furthermore, by adjusting the sheath thickness or selecting a sheath made of other materials, the minimum drilling spacing of the water inlet holes on the sheath will change accordingly.

[0092] It should be noted that the above-mentioned umbilical cable perforation method can be applied to the armor sheath 310 and the outer sheath 20 in the umbilical cable.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for perforating an umbilical cable, characterized in that, the umbilical cable comprises: an inner sheath, an inner layer functional unit group, an outer sheath, an outer layer functional unit group and an armor layer; the inner layer functional unit group is arranged in the inner sheath, the outer layer functional unit group is arranged between the inner sheath and the outer sheath, and the armor layer comprises an armor sheath and a metal armor, the metal armor being arranged between the armor sheath and the outer sheath; the outer sheath is provided with a plurality of first water inlet holes spaced apart along the length direction, and the armor sheath is provided with a plurality of second water inlet holes spaced apart along the length direction; the perforating method comprises: obtaining material data and thickness data of the sheath, and determining the allowable tearing stress of the sheath based on the material data and thickness data of the sheath; lowering one end of the umbilical cable into water at a speed V, so that an air column with a length L is formed in the sheath; determining the internal pressure P1 of the top end of the air column based on the lowering speed V of the umbilical cable and the length L of the air column in the umbilical cable; determining hoop stresses σ of the inner and outer surfaces of the sheath based on the internal pressure P1 at the top of the air column H ; circumferential stress σ H respectively, and the punching interval of the water inlet hole on the sheath is determined according to the comparison result.

2. The method of claim 1, wherein, the distance between adjacent first water inlet holes is 50m to 150m, and the distance between adjacent second water inlet holes is 50m to 150m.

3. The method of claim 1, wherein, the inner layer functional unit group comprises a plurality of first steel pipe units uniformly distributed in the inner sheath in the circumferential direction, and a second steel pipe unit filled between adjacent first steel pipe units; the outer layer functional unit group comprises a plurality of electrical units arranged in the circumferential direction, and the plurality of electrical units divide the area between the inner sheath and the outer sheath into a plurality of installation spaces, and at least one third steel pipe unit is arranged in the installation space.

4. The method of claim 3, wherein, the inner layer functional unit group comprises three first steel pipe units arranged in an equilateral triangle, and the second steel pipe unit is arranged between adjacent first steel pipe units, and the diameter of the first steel pipe unit is greater than the diameter of the second steel pipe unit; and / or, the outer layer functional unit group comprises four electrical units arranged in the circumferential direction, and the four electrical units divide the area between the inner sheath and the outer sheath into two first installation spaces and two second installation spaces, the two first installation spaces are oppositely arranged, and the two second installation spaces are oppositely arranged, three third steel pipe units are arranged in the first installation space, and one fourth steel pipe unit is arranged in the second installation space.

5. The method of claim 4, wherein, two first fillers are further arranged in the first installation space, the outer side of the first filler is attached to the outer sheath, one inner side of the first filler is attached to the third steel pipe unit at the first end of the first installation space, and the other inner side of the first filler is attached to the third steel pipe unit at the second end of the first installation space, the first end of the first filler abuts against the corresponding electrical unit, and the second end of the first filler abuts against the third steel pipe unit at the middle.

6. The method of punching a umbilical cable according to claim 4, wherein, two second fillers are further arranged in the second installation space, the outer side of the second filler is attached to the inner surface of the outer sheath, the inner side of the second filler is attached to the outer surface of the inner sheath, the first end of the second filler is attached to the corresponding electrical unit, and the second end of the second filler is attached to the fourth steel pipe unit.

7. The method of punching a umbilical cable according to claim 6, characterized in that, The second filler is provided with at least one deformation channel.

8. The method of claim 1, wherein, The internal pressure P1 of the air column top end satisfies: where γ = p air × g, P2= p water × g x L, p air is the air density, p water is the seawater density.

9. The method of claim 1, wherein, The circumferential stress σ H satisfies: where σ r is the radial stress of the jacket, R1 is the inner diameter of the jacket, R2 is the outer diameter of the jacket, and r is the radius value in the A, B coefficient calculation formula.

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