Umbilical cable and umbilical cable punching method

Abstract

The invention relates to the technical field of submarine cables, in particular to an umbilical cable and an umbilical cable punching method. The umbilical cable comprises an inner sheath, an inner layer function unit group, an outer sheath, an outer layer function unit group and an armor layer. The inner layer function unit group is arranged in the inner sheath, the outer layer function unit group is arranged between the inner sheath and the outer sheath, the armor layer comprises an armor sheath and a metal armor, and the metal armor is arranged between the armor sheath and the outer sheath; the outer sheath is provided with a plurality of first water inlet holes at intervals along the length direction, and the armored sheath is provided with a plurality of second water inlet holes at intervals along the length direction. According to the umbilical cable provided by the invention, the plurality of first water inlet holes are formed in the outer sheath at intervals, and the plurality of second water inlet holes are formed in the armored sheath along the length direction at intervals, so that seawater can enter a space in which the outer-layer functional unit group is located through the second water inlet holes and the first water inlet holes in sequence; friction torque between the outer layer function unit group and the outer sheath can be reduced, and birdcage accidents caused by torque accumulation can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of submarine cables, and in particular to an umbilical cable and an umbilical cable drilling method. Background Art

[0002] The steel tube type optoelectronic liquid composite umbilical cable for underwater production system is one of the key components of underwater production system, especially deepwater production system. Its main function is to provide electrical hydraulic power and chemical injection channels for underwater production system, and provide data transmission channels for upper module control signals and underwater production system.

[0003] Traditional deepwater umbilical cables generally include a functional unit group and an outer sheath that wraps the functional unit group. However, due to the special working environment of deepwater umbilical cables, the umbilical cables are prone to bending and swinging under the action of ocean currents, resulting in a large friction torque between the functional unit and the outer sheath. The accumulated torque can easily cause birdcage accidents. "Birdcage accidents" refer to the armor layer or functional unit of the cable, which is subjected to excessive twisting or bending, resulting in partial fracture or deformation of the armor layer, thus forming damage similar to the birdcage structure. This damage will lead to the exposure of the internal structure of the cable, which may cause cable function failure, insulation damage or other failures. Summary of the invention

[0004] The invention provides an umbilical cable and an umbilical cable punching method, which are used to solve the defect that the existing deep-water umbilical cable is prone to cause bird cage accidents.

[0005] One aspect of 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 arranged in the inner sheath, the outer functional unit group is arranged between the inner sheath and the outer sheath, the armor layer includes an armor sheath and a metal armor, and the metal armor is arranged between the armor sheath and the outer sheath; the outer sheath is provided with a plurality of first water inlet holes at intervals along the length direction, and the armor sheath is provided with a plurality of second water inlet holes at intervals along the length direction.

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

[0008] According to the umbilical cable provided by the present invention, the inner layer functional unit group includes a plurality of first steel tube units uniformly distributed in the inner sheath along the circumferential direction, and the second steel tube units filled between adjacent first steel tube units; the outer layer functional unit group includes a plurality of electrical units arranged at intervals along 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 tube unit is provided in the installation space.

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

[0010] And / or, the outer layer functional unit group includes four electrical units arranged at intervals along 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 arranged opposite to each other, and the two second installation spaces are arranged opposite to each other, three third steel pipe units are adjacent to each other in the first installation space, and a fourth steel pipe unit is arranged in the second installation space.

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

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

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

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

[0015] Material data and thickness data of the sheath are obtained, and the allowable tear stress of the sheath is determined based on the material data and thickness data of the sheath.

[0016] One end of the umbilical cable is lowered into the water at a speed V, so that an air column with a length of L is formed in the sheath.

[0017] Based on the lowering speed V of the umbilical cable and the length L of the air column in the umbilical cable, the internal pressure P at the top of the air column is determined. 1 .

[0018] Based on the internal pressure P at the top of the air column 1 , determine the hoop stress on the inner and outer surfaces of the jacket .

[0019] The hoop stress on the inner and outer surfaces of the jacket The stresses are compared with the allowable tear stress of the sheath respectively, and the punching spacing of the water inlet holes on the sheath is determined according to the comparison results.

[0020] According to the umbilical cable drilling method provided by the present invention, the internal pressure P at the top of the air column 1 Satisfy the following formula.

[0021] ; in, γ = , is the air density, is the density of sea water.

[0022] According to the umbilical cable drilling method provided by the present invention, the hoop stress Satisfy the following formula.

[0023] ; =- ; ; ; in, is the radial stress of the sheath, is the inner diameter of the sheath, is the outer diameter of the sheath, It is the radius value in the A and B coefficient calculation formula.

[0024] The umbilical cable provided by the present invention has a plurality of first water inlet holes spaced apart on the outer sheath, and a plurality of second water inlet holes spaced apart along the length direction on the armored sheath, so that seawater can enter the space where the outer functional unit group is located through the second water inlet holes and the first water inlet holes in sequence. Under the action of seawater, the friction torque between the outer functional unit group and the outer sheath can be reduced, thereby avoiding torque accumulation and causing birdcage accidents.

[0025] The umbilical cable punching method provided by the present invention can determine the minimum spacing of the holes punched on the sheath according to the material and thickness of the sheath, thereby preventing the umbilical cable from being crushed and exploded by internal pressure during the lowering process.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a schematic cross-sectional view of an umbilical cable provided in an embodiment of the present invention.

[0029] Figure 2 It is a schematic diagram of the flow of the umbilical cable drilling method provided in an embodiment of the present invention.

[0030] Figure 3 It is a schematic diagram of step S220 in the umbilical cable drilling method provided in an embodiment of the present invention.

[0031] Figure 4 This is one of the force analysis diagrams of the sheath in the umbilical cable drilling method provided in an embodiment of the present invention.

[0032] Figure 5 This is the second stress analysis diagram of the sheath in the umbilical cable drilling method provided in an embodiment of the present invention.

[0033] Reference numerals: 10. Inner sheath; 110. Inner functional unit group; 111. First steel tube unit; 112. Second steel tube unit; 20. Outer sheath; 210. Outer functional unit group; 211. Electrical unit; 212. Third steel tube unit; 213. Fourth steel tube unit; 214. First filling piece; 215. Second filling piece; 216. Optical unit; 30. Armor layer; 310. Armor sheath; 320. Metal armor. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and 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 devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0036] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0037] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0038] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0039] Combine the following Figures 1 to 5 The present invention describes an umbilical cable and an umbilical cable drilling method.

[0040] See also Figure 1 As shown, the umbilical cable provided by the embodiment of the present invention includes: an inner sheath 10 , an inner layer functional unit group 110 , an outer sheath 20 , an outer layer functional unit group 210 and an armor layer 30 .

[0041] The inner functional unit group 110 is arranged in the inner sheath 10, the outer functional unit group 210 is arranged between the inner sheath 10 and the outer sheath 20, the armor layer 30 includes an armor sheath 310 and a metal armor 320, and the metal armor 320 is arranged between the armor sheath 310 and the outer sheath 20; the outer sheath 20 is provided with a plurality of first water inlet holes at intervals along the length direction, and the armor sheath 310 is provided with a plurality of second water inlet holes at intervals along the length direction.

[0042] The umbilical cable provided by the present invention has a plurality of first water inlet holes spaced apart on the outer sheath 20, and a plurality of second water inlet holes spaced apart along the length direction on the armored sheath 310. Seawater can enter the space where the outer functional unit group 210 is located through the second water inlet holes and the first water inlet holes in sequence. Under the action of seawater, the friction torque between the outer functional unit group 210 and the outer sheath 20 can be reduced, thereby avoiding torque accumulation and causing birdcage accidents.

[0043] Specifically, the outer jacket 20 is provided with a plurality of first water inlet holes at intervals along the length direction, and the plurality of first water inlet holes can be arranged in the outer jacket 20 in a uniformly spaced manner. For example, the spacing between adjacent first water inlet holes is 100m. The plurality of first water inlet holes can also be arranged in the outer jacket 20 in a non-uniformly spaced manner, for example, the spacing between adjacent first water inlet holes is between 50m and 150m. Similarly, the plurality of second water inlet holes can be arranged in the outer jacket 20 in a uniformly spaced manner. For example, the spacing between adjacent second water inlet holes is 100m. The plurality of second water inlet holes can also be arranged in the outer jacket 20 in a non-uniformly spaced manner, for example, the spacing between adjacent second water inlet holes is between 50m and 150m.

[0044] It should be noted that the spacing between adjacent first water inlet holes / second water inlet holes is the center spacing of the holes. For example, when the first water inlet holes / second water inlet holes are circular holes, the spacing between adjacent first water inlet holes / second water inlet holes is the center spacing of the circles.

[0045] The shapes of the first water inlet hole and the second water inlet hole can be regular shapes such as circle, triangle, square, etc., or can be other irregular shapes, which are not specifically limited in the present invention.

[0046] The inner layer functional unit group 110 and the outer sheath 20 functional unit group may both include a steel pipe unit, an electrical unit 211 , an optical unit 216 , a filling member, and the like.

[0047] The steel pipe unit is used to provide a gas or liquid transmission channel for the underwater production system. For example, the steel pipe unit can be used to transport gas or liquid fuel or chemical agents to the underwater production system.

[0048] The electrical unit 211 is used to provide transmission power or electrical signals to the underwater production system.

[0049] The optical unit 216 is used to detect the bending deformation of the umbilical cable. The optical fiber sensor in the optical unit 216 can sense the change in the optical signal caused by the bending. Specifically, when the umbilical cable is bent, the refractive index and optical path of the optical fiber will change, thereby affecting the transmission and intensity of the optical signal. These changes can be detected and analyzed to monitor and evaluate the bending degree and possible damage of the umbilical cable, and can detect the bending and damage location of the umbilical cable.

[0050] The filler is used to fix the steel pipe unit, the electrical unit 211, the optical unit 216 and other functional units in the internal structure of the umbilical cable, helping to maintain the relative positions between the functional units and preventing them from moving when the umbilical cable is bent or stressed. The filler can prevent the displacement of the functional units inside the umbilical cable, thereby reducing the risk of damage caused by vibration, impact or external pressure. In addition, the filler helps to maintain the structural stability and shape consistency of the entire umbilical cable, ensuring the mechanical strength and durability of the umbilical cable during operation.

[0051] It should be noted that both the inner layer functional unit group 110 and the outer sheath 20 functional unit group may include at least one of the steel pipe unit, the electrical unit 211, and the optical unit 216, and may include or exclude fillers. The number of the steel pipe unit, the electrical unit 211, and the optical unit 216 in the inner layer functional unit group 110 and the outer sheath 20 functional unit group may be single or multiple, and is set according to the specifications of the umbilical cable and specific usage requirements, and the present invention does not specifically limit this.

[0052] The armor layer 30 is used to mechanically protect the functional units of the umbilical cable, and includes a metal armor 320 and an armor sheath 310. The metal armor 320 is mounted on the outer sheath 20, and the armor sheath 310 is mounted on the metal armor 320. The metal armor 320 is usually formed by a plurality of metal wires tightly wrapped around the outer sheath 20 and the armor sheath 310 to form the armor layer 30.

[0053] According to some embodiments of the present invention, the spacing between adjacent first water inlet holes is 50m to 150m, and the spacing between adjacent second water inlet holes is 50m to 150m. By setting the spacing between the first water inlet holes / the second water inlet holes to 50m to 150m, it can be ensured that seawater can enter the interior of the umbilical cable through the water inlet holes at different positions, and the sheath of the umbilical cable can be prevented from being broken by the internal pressure during the process of lowering the umbilical cable into the sea.

[0054] Specifically, the sheath (including the outer sheath 20 and the armored sheath 310) is usually made of HDPE (High-Density Polyethylene) material, and its thickness is usually set between 3mm and 10mm (such as 5mm). During the lowering of the umbilical cable, an air column will be generated in the sheath, which will generate internal pressure on the sheath and exert hoop stress. When the hoop 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 hole / the second water inlet hole to 50m to 150m, it can be ensured that the hoop stress exerted by the air column in the sheath during the lowering of the umbilical cable is within the allowable tear stress, thereby preventing damage to the sheath.

[0055] See also Figure 1 and Figure 2As shown, according to some embodiments of the present invention, the inner layer functional unit group 110 includes a plurality of first steel pipe units 111 uniformly distributed in the inner sheath 10 along the circumferential direction, and a second steel pipe unit 112 filled between adjacent first steel pipe units 111; the outer layer functional unit group 210 includes a plurality of electrical units 211 spaced apart along the circumferential direction, and the plurality of electrical units 211 divide the area between the inner sheath 10 and the outer sheath 20 into a plurality of installation spaces, and at least one third steel pipe unit 212 is arranged in the installation space. Through the above arrangement, the plurality of first steel pipe units 111 arranged in the inner layer along the circumferential direction and the second steel pipe unit 112 filled between adjacent first steel pipe units 111 can provide a plurality of gas or liquid transmission channels, and at the same time, a stable support structure can be formed in the inner layer of the umbilical cable to provide stable support for the outer layer functional unit group 210. The electrical unit 211 divides the area between the inner sheath 10 and the outer sheath 20 into a plurality of installation spaces, which helps to organize and protect the internal functional units and reduce interference. At the same time, the third steel pipe unit 212 forms an additional protective layer on the outer layer of the umbilical cable, thereby improving the protection capability of the internal components, thereby increasing the durability and service life of the cable.

[0056] See also Figure 1 As shown, according to some embodiments of the present invention, the inner layer functional unit group 110 includes three first steel pipe units 111 ( Figure 1 Numbers 1, 2, and 3 in the figure), a second steel pipe unit 112 is provided between adjacent first steel pipe units 111 ( Figure 1 4, 5, and 6 in the figure), the diameter of the first steel tube unit 111 is greater than the diameter of the second steel tube unit 112. By limiting the size and number of the first steel tube unit 111 and the second steel tube unit 112, the three first steel tube units 111 distributed in an equilateral triangle can be fixed to each other, and the second steel tube unit 112 can be fixed by the adjacent first steel tube unit 111. At the same time, the outer sides of the first steel tube unit 111 and the second steel tube unit 112 can abut against the inner sheath 10, so that the first steel tube unit 111 and the second steel tube unit 112 located in the inner layer can remain stable.

[0057] Specifically, in this embodiment, the diameter of the first steel pipe unit 111 is twice the diameter of the second steel pipe unit 112 .

[0058] See also Figure 1 As shown, according to some embodiments of the present invention, the outer layer functional unit group 210 includes four electrical units 211 arranged at intervals along the circumferential direction, and the four electrical units 211 divide the area between the inner sheath 10 and the outer sheath 20 into two first installation spaces and two second installation spaces, the two first installation spaces are arranged opposite to each other, the two second installation spaces are arranged opposite to each other, and three third steel pipe units 212 ( Figure 1Numbers 7, 8, 9, 10, 11, 12), a fourth steel pipe unit 213 ( Figure 1 11, 12). By dividing the area into multiple installation spaces, the utilization of the internal space and the organization of components are optimized, while the configuration of four electrical units 211 and multiple steel pipe units enhances the mechanical strength and stability of the cable.

[0059] See also Figure 1 As shown, according to some embodiments of the present invention, two first filling pieces 214 are further provided in the first installation space, and the outer side of the first filling piece 214 is in contact with the outer sheath 20, the inner side of one of the first filling pieces 214 is in contact with the third steel tube unit 212 located at the first end of the first installation space, and the inner side of the other first filling piece 214 is in contact with the third steel tube unit 212 located at the second end of the first installation space, and the first end of the first filling piece 214 abuts against the corresponding electrical unit 211, and the second end of the first filling piece 214 abuts against the third steel tube unit 212 located in the middle. By providing two first filling pieces 214 in the first installation space, the gap between the third steel tube unit 212 and the outer sheath 20 can be filled, and the three third steel tube units 212 can be stably supported at the same time to prevent the third steel tube units 212 from slipping.

[0060] It should be noted that the above-mentioned “first end of the first filling piece 214 ” specifically refers to an end of the first filling piece 214 close to the adjacent dot unit, and the above-mentioned “second end of the first filling piece 214 ” specifically refers to an end of the first filling piece 214 away from the adjacent dot unit.

[0061] See also Figure 1 As shown, according to some embodiments of the present invention, two second filling pieces 215 are further provided in the second installation space, the outer side of the second filling piece 215 is in contact with the inner surface of the outer sheath 20, the inner side of the second filling piece 215 is in contact with the outer surface of the inner sheath 10, the first end of the second filling piece 215 is in contact with the corresponding electrical unit 211, and the second end of the second filling piece 215 is in contact with the fourth steel pipe unit 213. The second filling piece 215 can fill the gap between the inner sheath 10 and the outer sheath 20, provide additional support for the fourth steel pipe unit 213, and enhance the stability of the overall structure. At the same time, by providing two second filling pieces 215 in the second installation space, the fourth steel pipe unit 213 can be limited and fixed by the second filling piece 215 to ensure its stability.

[0062] See also Figure 1As shown, according to some embodiments of the present invention, an optical unit 216 for detecting the bending degree of the umbilical cable is further provided between the second filling piece 215 and the outer sheath 20, and at least one deformation channel is provided in the second filling piece 215. By providing the optical unit 216, the bending and damage position of the umbilical cable can be detected. At least one deformation channel is provided in the second filling piece 215, which can deform when the umbilical cable is bent and stretched under high load, and there is a slip tendency between the optical unit 216 and the outer sheath 20, so that the optical unit 216 adjusts its own strain and reduces damage accumulation.

[0063] Specifically, the optical fiber sensor in the optical unit 216 senses the change in the optical signal caused by bending. When the umbilical cable is bent, the refractive index and optical path of the optical fiber will change, thereby affecting the transmission and intensity of the optical signal. These changes can be detected and analyzed to monitor and evaluate the degree of bending and possible damage of the umbilical cable, and to detect the bending and damage location of the umbilical cable.

[0064] The following is a description of the umbilical cable punching method provided by the present invention. The umbilical cable punching method described below and the umbilical cable described above can be referenced to each other.

[0065] See also Figure 2 As shown, the umbilical cable drilling method provided by the embodiment of the present invention includes the following steps.

[0066] S210, obtaining material data and thickness data of the sheath, and determining the allowable tear stress of the sheath based on the material data and thickness data of the sheath.

[0067] S220. Lower one end of the umbilical cable into the water at a speed V, so that an air column with a length of L is formed in the sheath (which can be regarded as the opening distance of the sheath is L).

[0068] S230, based on the lowering speed V of the umbilical cable and the length L of the air column in the umbilical cable, determine the internal pressure P at the top of the air column 1 .

[0069] S240, based on the internal pressure P at the top of the air column 1 , determine the hoop stress on the inner and outer surfaces of the jacket .

[0070] S250, the hoop stress on the inner and outer surfaces of the sheath The stresses are compared with the allowable tearing stress of the sheath respectively, and the punching spacing of the water inlet holes on the sheath is determined according to the comparison results.

[0071] The umbilical cable punching method provided by the present invention can determine the minimum spacing of the holes punched on the sheath according to the material and thickness of the sheath, thereby preventing the umbilical cable from being crushed and exploded by internal pressure during the lowering process.

[0072] Specifically, in step S210, after obtaining the material data and thickness data of the sheath, the initial value of the allowable tear stress of the sheath can be obtained. Usually, the final value of the allowable tear stress can be obtained by calculating according to the allowable coefficient k. For example, the outer sheath is made of HDPE material with a thickness of 5mm, and the initial value of the allowable tear stress is 26Mpa. According to the allowable coefficient k=0.67, the final value of the allowable tear stress is 17.42MPa. Step S220 can be found in Figure 3 shown.

[0073] See also Figures 3 to 5 As shown, according to some embodiments of the present invention, the internal pressure P at the top of the air column 1 Satisfy the following formula.

[0074] ; in, γ = , is the air density, is the density of sea water.

[0075] Specifically, according to the water depth L and lowering speed V , we can find the internal pressure at the top of the air column At this time, the top of the air column is considered to have no external pressure. As the air column grows and the speed of lowering increases, the jacket is under internal pressure. Therefore, it is necessary to control the minimum perforation spacing of the jacket to prevent the jacket from being squeezed and exploded during the lowering process. Crowded.

[0076] See also Figures 3 to 5 As shown, according to some embodiments of the present invention, the hoop stress Satisfy the following formula.

[0077] ; ; ; ; in, is the radial stress of the sheath, is the inner diameter of the sheath, is the outer diameter of the sheath, It is the radius value in the A and B coefficient calculation formula.

[0078] when = or When the radial stress The value of is shown in the following formula, which is used to analyze the limit value. For example, when = hour, =- ,when = hour, .

[0079] Specifically, the internal pressure of the sheath Can be regarded as negative radial stress The above formula can be used to calculate the hoop stress on the sheath: , and then the calculated hoop stress By comparing with the allowable tearing stress value of the sheath, the opening distance of the water inlet holes on the sheath can be adjusted to avoid the sheath from being squeezed and exploded.

[0080] 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 punching spacing of the water inlet holes on the sheath is 76m. In addition, by adjusting the sheath thickness or selecting a sheath made of other materials, the minimum punching spacing of the water inlet holes on the sheath changes accordingly.

[0081] It should be noted that the above-mentioned umbilical cable drilling method can be applied to the armored sheath 310 and the outer sheath 20 in the umbilical cable.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An umbilical cable, characterized in that: include: Inner sheath, inner functional unit group, outer sheath, outer functional unit group and armor layer; The inner functional unit group is arranged in the inner sheath, the outer functional unit group is arranged between the inner sheath and the outer sheath, the armor layer includes an armor sheath and a metal armor, and the metal armor is arranged between the armor sheath and the outer sheath; The outer sheath is provided with a plurality of first water inlet holes at intervals along the length direction, and the armor sheath is provided with a plurality of second water inlet holes at intervals along the length direction.

2. The umbilical cable according to claim 1, characterized in that: 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 umbilical cable according to claim 1, characterized in that: The inner layer functional unit group includes a plurality of first steel tube units uniformly distributed in the inner sheath along the circumferential direction, and the second steel tube units filled between adjacent first steel tube units; The outer layer functional unit group includes a plurality of electrical units spaced apart along 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, wherein at least one third steel pipe unit is disposed in the installation space.

4. The umbilical cable according to claim 3, characterized in that: The inner layer functional unit group includes three first steel tube units distributed in an equilateral triangle, the second steel tube unit is arranged between adjacent first steel tube units, and the diameter of the first steel tube unit is greater than the diameter of the second steel tube unit; And / or, the outer layer functional unit group includes four electrical units arranged at intervals along 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 arranged opposite to each other, and the two second installation spaces are arranged opposite to each other, three third steel pipe units are adjacent to each other in the first installation space, and a fourth steel pipe unit is arranged in the second installation space.

5. The umbilical cable according to claim 4, characterized in that: Two first filling pieces are also provided in the first installation space, and the outer sides of the first filling pieces are in contact with the outer sheath, the inner side of one of the first filling pieces is in contact with the third steel pipe unit located at the first end of the first installation space, and the inner side of the other first filling piece is in contact with the third steel pipe unit located at the second end of the first installation space, the first end of the first filling piece abuts against the corresponding electrical unit, and the second end of the first filling piece abuts against the third steel pipe unit located in the middle.

6. The umbilical cable according to claim 4, characterized in that: Two second filling pieces are also provided in the second installation space, the outer side of the second filling piece is in contact with the inner surface of the outer sheath, the inner side of the second filling piece is in contact with the outer surface of the inner sheath, the first end of the second filling piece is in contact with the corresponding electrical unit, and the second end of the second filling piece is in contact with the fourth steel pipe unit.

7. The umbilical cable according to claim 6, characterized in that An optical unit for detecting the bending degree of the umbilical cable is further provided between the second filling piece and the outer sheath, and at least one deformation channel is provided in the second filling piece.

8. A method for drilling a hole in an umbilical cable, characterized in that: include: Acquiring material data and thickness data of the sheath, and determining the allowable tear stress of the sheath based on the material data and thickness data of the sheath; Lowering one end of the umbilical cable into the water at a speed V, so that an air column with a length of L is formed in the sheath; Based on the lowering speed V of the umbilical cable and the length L of the air column within the umbilical cable, determine the internal pressure P1 at the top of the air column; Based on the internal pressure P1 at the top of the air column, the hoop stress on the inner and outer surfaces of the jacket is determined. ; The hoop stress on the inner and outer surfaces of the jacket The stresses are compared with the allowable tear stress of the sheath respectively, and the punching spacing of the water inlet holes on the sheath is determined according to the comparison results.

9. The umbilical cable drilling method according to claim 8, characterized in that: The internal pressure P1 at the top of the air column satisfies: ; in, γ = , is the air density, is the density of sea water.

10. The umbilical cable drilling method according to claim 8, characterized in that: The hoop stress satisfy: ； =- ； ; ; in, is the radial stress of the sheath, is the inner diameter of the sheath, is the outer diameter of the sheath, It is the radius value used in the A and B coefficient calculation formulas.

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