阅读说明：本技术 将电缆安装到管道中 (Installing a cable into a conduit ) 是由 威廉·格里福恩 亚历山大·于尔 克里斯托夫·古特伯雷 于 2019-04-03 设计创作，主要内容包括：用于将电缆安装到管道中的方法,该方法包括以下步骤：-确定最大压力,-设定泄漏塞的泄漏模式,以泄漏压降开始,泄漏压降等于或低于最大压力,-将泄漏塞附接到电缆的最前端,-将电缆的最前端引入管道中,-将加压液体供应到管道中：在供应端口处和在供应压力下,使得电缆被泄漏塞拉动,-在最前端到达第二末端之前,在靠近泄漏塞的位置处超过了泄漏压降。(A method for installing a cable into a conduit, the method comprising the steps of: -determining a maximum pressure, -setting a leakage pattern of the leakage plug, starting with a leakage pressure drop, which is equal to or lower than the maximum pressure, -attaching the leakage plug to the foremost end of the cable, -introducing the foremost end of the cable into the conduit, -supplying a pressurized liquid into the conduit: at the supply port and under supply pressure, such that the cable is pulled by the leakage plug, -the leakage pressure drop is exceeded at a location close to the leakage plug before the foremost end reaches the second end.)

1. Method for installing a cable (1) into a conduit (3) having two ends, the method comprising the steps of:

-determining a maximum pressure (p) based on the burst pressure or working pressure of the pipe (3) taking into account the installation temperature and/or the installation time_max)，

-setting the leakage pattern of the leakage plug (7) to a leakage pressure drop (Δ ρ) over the entire leakage plug (7)_{Leakage of}) Initially, the leakage pressure drop is determined to be equal to or lower than the maximum pressure (p)_max)，

-attaching the leakage plug (7) to the foremost end of the cable (1),

-introducing the forwardmost end of the cable (1) into the conduit (3) at a first end (31),

-supplying a pressurized liquid into the conduit (3):

supplying a pressurized liquid into the conduit at a supply port arranged between the foremost end equipped with the leakage plug (7) and the first end (31), and

at the supply pressure (p)_sup) Supplying pressurized liquid into the conduit at a supply pressure equal to or higher than a predetermined pressure,

so that the cable (1) is pulled by the leakage plug (7),

-the leakage pressure drop (Δ ρ) is exceeded at a position close to the leakage plug (7) before the foremost end reaches a second end (32)_{Leakage of}) Causing the leakage mode to begin.

2. Method according to the preceding claim, wherein the duct (3) presents a trajectory with a non-constant height, comprising the steps of: adjusting the supply pressure (p) before the foremost end reaches the second end (32)_sup) Such that along the portion of the duct (3) between the first end (31) and the foremost end of the cable (1) filled with liquid, the pressure of the liquid is each lower than the maximum pressure (p)_max)。

3. The method according to the preceding claim, wherein the supply pressure is regulated so that, at any point along the portion of the duct (3) between the first end (31) and the forwardmost end of the cable (1) filled with liquid:

-for a point at a height above said first end (31), said supply pressure (p)_sup) Less the pressure loss caused by the viscosity of the liquid reaching the point considered, greater than the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the point considered and the height of the first end (31), and/or

-said supply pressure (p) for a point at a lower level than said first end (31)_sup) Less the pressure loss caused by the viscosity of the liquid reaching the point considered, plus the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the point considered and the height of the first end (31), is greater than zero and lower than the maximum pressure (p)_max)。

4. The method of any of claims 1-3, wherein:

-adjusting the supply pressure (p) if the second end is located at a higher level than the first end_sup) Such that said supply pressure (p)_sup) Minus the pressure loss caused by the viscosity of the liquid over the entire length of the pipe, minus the leakage pressure drop (Δ p)_{Leakage of}) Equal to the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the second end and the height of the first end, or

-adjusting the supply pressure (p) if the second end is located at a lower height than the first end_sup) Such that said supply pressure (p)_sup) Minus the pressure loss caused by the viscosity of the liquid over the entire length of the pipe, minus the leakage pressure drop (Δ p)_{Leakage of}) And, plus the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the second end and the height of the first end, is equal to 0.

5. The method according to any one of the preceding claims, further comprising the step of: when the leakage mode is started, the pressurized liquid is supplied at a flow rate exceeding the leakage flow rate of the leakage plug (7).

6. Method according to any of the preceding claims, wherein before the start of the leakage mode, a flow rate Φ defined in the following formula is used_vSupplying the pressurized liquid:

wherein:

Φ_vis the flow rate (m) of the supplied pressurized liquid³/s)，

D_cIs the outer diameter (m) of the cable (1),

D_dis the inner diameter (m) of the pipe (3),

v_{cable with a protective layer}Is the speed (m/s) at which the cable (1) enters the conduit.

7. The method of any preceding claim, wherein:

-the two ends are located at different heights, and

-introducing the forwardmost end of the cable (1) at the first end (31) of the duct (3), which is the end located at the highest height.

8. Method according to any of the preceding claims, wherein the leakage pressure drop (Δ ρ) is adjusted during installation_{Leakage of}) And wherein:

-said leakage pressure drop (Δ p)_{Leakage of}) Increase before the leakage plug (7) travels through the uphill section of the pipe (3), or gradually during the travel of the leakage plug through the uphill section of the pipe, or

-said leakage pressure drop (Δ p)_{Leakage of}) -reducing before or during the travel of the leakage plug (7) through the downhill section of the pipe (3).

9. The method according to any of the preceding claims, wherein the method comprises the following initial steps:

-measuring or determining the inner diameter of the pipe (3), the outer diameter of the cable (1) and the slope of the pipe (3) between its ends,

-setting the leakage surface of the leakage plug (7) equal to or greater than the diameter D_Hole(s)The surface of the circular hole of (a):

more preferably:

even more preferably:

wherein:

wherein:

D_cis the outer diameter (m) of the cable (1),

D_dis the inner diameter (m) of the pipe,

Δp_{leakage of}Is the leakage pressure drop (Pa) across the leakage plug (7),

ρ_wis the density (kg/m) of the pressurized liquid³)，

Alpha is the average angle of the pipe (3) to the horizontal plane,

g is the acceleration of gravity (9.81 m/s)²)，

μ_wIs the dynamic viscosity (Pas) of the pressurised liquid.

10. Method according to claim 1, wherein the pipe (3) has an almost horizontal trajectory, and wherein the method comprises the initial steps of:

-measuring or determining the inner diameter of the pipe (3), the outer diameter of the cable (1),

-setting the leakage surface of the leakage plug (7) equal to or greater than the diameter D_Hole(s)The surface of the circular hole of (a):

more preferably:

even more preferably:

wherein:

wherein:

D_cis the outer diameter (m) of the cable (1),

D_dis the inner diameter (m) of the pipe,

Δp_{leakage of}Is the leakage pressure drop (Pa) across the leakage plug (7),

ρ_wis the density (kg/m) of the pressurized liquid³)，

μ_wIs the dynamic viscosity (Pas) of the pressurised liquid.

11. Method according to any one of the preceding claims, wherein the flow rate of the pressurized liquid supplied into the conduit (3) is:

-before the leakage mode starts, is set to a first flow value Φ_v1，

-after the start of the leakage mode, set to a second flow Φ_v2，

Wherein phi_v2≥5Φ_v1。

12. The method according to any one of the preceding claims, comprising the steps of: before the leak mode begins, the pump used to supply the pressurized liquid is changed.

13. The method according to any one of the preceding claims, the method comprising:

-a step of measuring the pressure during installation at a location close to the leakage plug (7),

-correcting the supply pressure (p) according to the pressure measured at a position close to the leakage plug (7)_sup) The step (2).

Technical Field

The present invention relates to the installation or introduction or laying of cables into pipelines.

Background

Installation of the cable into a pipeline (buried or located on the seabed) may be achieved by floating techniques. In this technique, a cable is introduced into a conduit and a pressurized liquid is introduced simultaneously to generate a drag force along the cable to push the cable into the conduit. However, this technique for introducing large power cables into very large pipes requires very high flow rates, resulting in a high volume of liquid being supplied at the inlet of the pipe and discharged at the outlet of the pipe. In addition, high-flow pumps are required.

Installation of the cable into the pipeline (buried or located on the seabed) may also be achieved by pulling pigs (pull pigs) attached along the cable to push the cable by the pulling force generated by the pressurized liquid, but in this case too much pressure may damage the pipeline (risk of bursting) or the cable (risk of rupture). As disclosed in document WO2011054551a2, a liquid may be used when the pulling pig is attached to the cable.

Disclosure of Invention

The present invention aims to solve the above-mentioned drawbacks of the prior art and firstly proposes a method for installing a cable into a conduit, which method reduces the risk of damaging the conduit or the cable and/or reduces the risk of the need for liquid supply, while still aiming to run the cable through a long conduit.

To this end, a first aspect of the invention is a method for installing a cable into a conduit having two ends, the method comprising the steps of:

-determining a maximum pressure based on a burst pressure or working pressure of the conduit and/or based on a maximum strength of the cable,

-setting the leakage pattern of the leakage plug to start with a leakage pressure drop over the leakage plug, which is determined to be equal to or lower than the maximum pressure,

-attaching a leakage plug to the foremost end of the cable,

-introducing the foremost end of the cable into the conduit at the first end,

-supplying a pressurized liquid into the conduit:

supplying a pressurized liquid into the conduit at a supply port arranged between a forwardmost end provided with a leakage plug and the first end, and

supplying a pressurized liquid into the conduit at a supply pressure, the supply pressure being equal to or higher than a predetermined pressure,

so that the cable is pulled by the leakage plug,

-the leakage pressure drop is exceeded at a position close to the leakage plug before the foremost end reaches the second end, resulting in the leakage pattern starting. In other words, the above method proposes to use a pulling technique (no or almost no leakage at the leakage plug) in the first stage and a technique similar to the floating technique (large leakage of liquid at the leakage plug) to lay the cable into the pipeline in the second stage. During the first phase, the liquid supply is limited to the flow required to "follow" the cable (so no significant additional flow is required), and during the second phase, the pressure at the side of the leakage plug is no greater than the maximum pressure (so no excessive pressure is applied to the pipe wall or the cable).

According to one embodiment, the conduit exhibits a trajectory having a non-constant height, and the method comprises the steps of: the supply pressure is regulated before the forwardmost end reaches the second end, so that along the portion of the conduit between the first end and the forwardmost end of the cable filled with liquid, the pressure of the liquid is lower than the maximum pressure. In other words, the predetermined supply pressure is adjusted according to the slopes along the pipe and the distance of these slopes from the liquid inlet.

Advantageously, the maximum pressure is also determined taking into account the installation temperature and/or the installation time. In other words, as the first parameter considered, the value of the burst pressure or working pressure depends on the operating temperature and/or the installation time.

Advantageously, the supply pressure is regulated so that, at any point along the portion of the duct between the first end and the forwardmost end of the cable filled with liquid:

-for a point at a height above the first end, the supply pressure minus the pressure loss caused by the viscosity of the liquid reaching said considered point is greater than the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of said considered point and the height of the first end, and/or

-for points at a height lower than the first end, the supply pressure minus the pressure loss caused by the viscosity of the liquid reaching said considered point, plus the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of said considered point and the height of the first end, is greater than zero and lower than the maximum pressure.

Advantageously, the method further comprises the steps of: when the leak mode is initiated, pressurized liquid is supplied at a rate that exceeds the leak rate of the leak plug. During the second phase, the leakage plug is significantly opened in order to allow a substantial increase in the flow to be supplied at the supply port in order to push the cable with a significant drag force along the entire cable length.

Advantageously, before the start of the leakage mode, the flow Φ defined in the formula is_vSupplying a pressurized liquid:

wherein:

Φ_vis the supplied pressurized liquid flow rate (m)³/s)，

D_cIs the outer diameter (m) of the cable,

D_dis the inner diameter (m) of the pipe,

v_{cable with a protective layer}Is the velocity (m/s) of the cable into the conduit.

According to the above embodiment, during the first phase (before the start of the leakage mode) no or hardly any substantial liquid flow passes the closed or almost closed leakage plug.

Advantageously:

the two ends are located at different heights, and

-introducing the forwardmost end of the cable at a first end of the conduit, the first end being the end located at the highest level. The forwardmost end of the cable is introduced at the first end of the duct so that, due to the liquid density and the height difference between the highest level of the first end and the height of the forwardmost end, the pressure exerted at a location close to the leakage plug gradually increases while the leakage plug moves towards the second end located at the lowest level. The method is particularly suitable for laying cables in pipes which are oriented (usually) downhill. In other words, the installation is preferably done with the highest end to push the cable to the lowest end, since the leakage mode will automatically start when the supply pressure plus hydrostatic pressure exceeds the leakage pressure drop, thereby protecting the pipe and/or cable from excessive pressure. This method with medium term opening allows the installation of cables using a strict pulling technique (low demand for liquid) until the height difference switches the switch to leakage mode to avoid overpressure duct damage.

In summary, one aspect of the invention relates to a method for installing a cable into a conduit having two ends located at different heights, the method comprising the steps of:

-determining a maximum pressure based on a burst pressure of the conduit and/or based on a maximum strength of the cable,

-setting the leakage pattern of the leakage plug to start with a leakage pressure drop over the leakage plug, which is determined to be equal to or lower than the maximum pressure,

-attaching a leakage plug to the foremost end of the cable,

-introducing the forwardmost end of the cable into the conduit at the end having the highest height,

-supplying a pressurized liquid into the conduit:

supplying pressurized liquid into the conduit at a supply port arranged between a forwardmost end provided with a leakage plug and an end having the highest height, and

supplying a pressurized liquid into the conduit at a supply pressure, which is equal to or higher than a predetermined pressure,

so that the cable is pulled by the leakage plug,

-the leakage pressure drop is exceeded at a position close to the leakage plug before the foremost end reaches the lowest level end, resulting in the leakage pattern starting.

Advantageously, the supply pressure is set such that:

-the supply pressure minus the pressure loss caused by the viscosity of the liquid reaching the foremost end of the cable, plus the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the end of highest height and the height of the foremost end of the cable,

is less than:

-a maximum pressure. According to this embodiment, the supply pressure is calculated and limited to avoid any excessive stress along the downhill pipeline.

Advantageously, the supply pressure is set such that:

-the supply pressure minus the pressure loss caused by the viscosity of the liquid reaching the second end, plus the hydrostatic pressure caused by the density of the liquid and the difference in height between the two ends,

is less than:

-a maximum pressure. According to this embodiment, the supply pressure is calculated and limited to avoid any excessive stress along the downhill pipeline.

Advantageously, the supply pressure is set such that:

-the supply pressure minus the pressure loss caused by the viscosity of the liquid reaching a portion of the pipe having a height lower than the height of the second end, plus the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the first end and the height of the portion of the pipe having a height lower than the height of the second end,

is less than:

-a maximum pressure. According to this embodiment the supply pressure is calculated and limited such that any excessive stress along the downhill pipeline is avoided even if a part of the pipeline is located below the second end (at a lower level).

In any case, the predetermined pressure is equal to or higher than the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the first end and the height of the portion of the conduit having a height higher than the height of the first end. According to this embodiment the supply pressure is calculated such that it is ensured that the pipe will be filled with liquid even if a part of the pipe is located above the first end (at a higher level).

Advantageously, during installation, the leakage pressure drop is regulated, and:

-the leakage pressure drop increases before the leakage plug travels through the uphill section of the pipe, or gradually during the travel of the leakage plug through the uphill section of the pipe, or

-the leakage pressure drop is reduced before or gradually during the travel of the leakage plug through the downhill section of the pipe. According to this embodiment, the leakage plug is (remotely) controlled during installation to adjust its leakage pressure drop according to the rise/fall conditions. Particularly advantageously, the leakage pressure drop is performed after the leakage plug reaches a portion of the duct located at a level lower than the second end, and travels upwards with an increase in its height; this avoids the pipe being subjected to excessive stress at its lowest level.

Advantageously:

-adjusting the supply pressure (p) if the second end is located at a higher level than the first end_sup) So that the supply pressure (p) is_sup) Minus the pressure loss caused by the viscosity of the liquid over the entire length of the pipe, minus the leakage pressure drop (Δ p)_{Leakage of}) Equal to the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the second end and the height of the first end, or

-adjusting the supply pressure (p) if the second end is located at a lower height than the first end_sup) So that the supply pressure (p) is_sup) Minus the pressure loss caused by the viscosity of the liquid over the entire length of the pipe, minus the leakage pressure drop (Δ p)_{Leakage of}) And, plus the hydrostatic pressure caused by the density of the liquid and the difference in height between the height of the second end and the height of the first end, is equal to 0.

The above-described embodiment of adjusting the supply pressure according to the above-described conditions ensures that the pipe is filled with water even if the trajectory is not at a constant height and even if the leakage plug is in leakage mode.

Advantageously, the method comprises the following initial steps:

-measuring or determining the inner diameter of the pipe, the outer diameter of the cable and the slope between the ends of the pipe,

-setting the leakage surface of the leakage plug equal to or larger than the surface of the circular hole having a diameter:

wherein:

wherein:

D_cis the outer diameter (m) of the cable

D_dIs the inner diameter (m) of the pipe

Δp_{Leakage of}Is the leakage pressure drop (Pa) across the entire leakage plug

ρ_wIs the density (kg/m) of the pressurized liquid³)

Alpha is the average angle of the pipe to the horizontal

g is the acceleration of gravity (9.81 m/s)²)

μ_wIs the dynamic viscosity (Pas) of the pressurized liquid.

According to the above embodiment, once the leakage pattern begins, the leakage surface is calculated to allow a large amount of liquid flow.

Advantageously:

advantageously, the flow rate of the pressurized liquid supplied into the duct is:

before the start of the leakage mode,is set to a first flow value phi_v1，

-after the start of the leakage mode, set to a second flow Φ_v2，

Wherein phi_v2≥5Φ_v1。

In other words, one aspect of the present disclosure relates to the use of a leakage plug or a leakage plug having a leakage surface equal to the surface of a circular hole having a diameter that meets the following criteria:

if the pipe has a horizontal or nearly horizontal trajectory (the slope of the pipe from the horizontal is equal to or not greater than 5 °), the method comprises the initial steps of:

-measuring or determining the inner diameter of the pipe, the outer diameter of the cable,

-setting the leakage surface of the leakage plug equal to or greater than the diameter D_Hole(s)The surface of the circular hole of (a):

more preferably:

wherein:

wherein:

D_cis the outer diameter (m) of the cable,

D_dis the inner diameter (m) of the pipe,

Δp_{leakage of}Is the leakage pressure drop (Pa) across the entire leakage plug,

ρ_wis the density (kg/m) of the pressurized liquid³)，

μ_wIs the dynamic viscosity (Pas) of the pressurized liquid.

Advantageously:

wherein:

wherein:

D_cis the outer diameter (m) of the cable,

D_dis the inner diameter (m) of the pipe,

Δp_{leakage of}Is the leakage pressure drop (Pa) across the entire leakage plug,

ρ_wis the density (kg/m) of the pressurized liquid³)，

μ_wIs the dynamic viscosity (Pas) of the pressurized liquid.

Advantageously, the method comprises the steps of: before the leak mode begins, the pump used to supply the pressurized liquid is changed.

Advantageously, the method comprises:

-a step of measuring the pressure during installation at a location close to the leakage plug,

-a step of correcting the supply pressure on the basis of the pressure measured at a position close to the leaky plug.

Drawings

Other features and advantages of the invention will appear more clearly from the following detailed description of a particular non-limiting example of the invention, illustrated by the accompanying drawings, in which:

figure 1 shows an overall view of the installation of a cable into a duct using the method according to the invention;

figure 2 shows an example of a pulling pig that can be used during the installation shown in figure 1;

figure 3 shows an example of a trajectory of the pipe of figure 1, in which the pressure inside the pipe varies along its length;

figure 4 shows a pressure profile for installing a cable into the pipe of figure 3 according to a first scenario;

fig. 5 shows a liquid flow through a pulling pig during installation of the cable in the duct of fig. 3 according to a first scenario;

fig. 6 shows a pressure profile for installing a cable into the pipe of fig. 3 according to a second scenario;

fig. 7 shows a pressure profile for installing a cable into the pipe of fig. 3 according to a third scenario;

fig. 8 shows a pressure profile for installing a cable into the pipe of fig. 3 according to a fourth scenario;

fig. 9 shows a pressure profile for installing a cable into the pipe of fig. 3 according to a fifth scenario;

fig. 10 shows a pressure profile for installing a cable into the pipe of fig. 3 according to a sixth scenario.

Detailed Description

Fig. 1 shows an overall schematic view of the installation of a cable 1 into a conduit 3. The cable 1 is installed from the drum 2 into the pipe 3 by means of a device 4, which device 4 comprises a drive belt 5, a filling chamber 6 (where the liquid is water) and a leakage plug 7.

In order to push the cable 1 correctly into the conduit 3, a leakage plug 7 is attached to the foremost end of the cable 1, and after introduction into the conduit 3, water is injected under pressure into the conduit 3 via the water injection chamber 6, thereby creating a pressure on the leakage plug 7 in order to pull the cable into the conduit 3. Advantageously, there is only one single ingot or leakage plug 7 attached to the cable 1.

Fig. 2 shows a detailed view of a preferred embodiment of the leakage plug 7. The communication signal is coupled to the cable 1 (which typically includes an electrically shielded wire 10) by an inductive device 8 controlled by an electronic device 9. The electrical shielding 10 of the cable can be used, for example, for acquiring and transmitting said signals. This signal is then connected to battery operated electronics 11 arranged in the leakage plug 7, which electronics 11 control a solenoid 12 which operates a cylindrical valve 13, thereby changing the size of the opening 14. This opening 14 is arranged in series with the openings 15 and 16, so that the leakage plug can be opened or closed.

Optionally, a force sensor (not shown) may also be installed between the cable 1 and the leakage plug 7, included in the monitoring device. Optionally, a pressure sensor may be incorporated, enabling the local pressure in the vicinity of the leaky plug 7 to be measured and analyzed.

The cylindrical valve 13 may completely block the opening 14 so that the leakage plug 7 does not leak between its rear end (where the cable 1 is attached) and its opposite front end. The leakage plug 7 is considered to be operating in a non-leakage mode. Instead, the opening 14 may be fully open, and in this case the leakage plug 7 is considered to be operating in leakage mode.

In the leakage mode, a pressure drop will occur depending on the size of the holes and openings through which the liquid passes. This pressure drop will be referred to as leakage pressure drop Δ p in the following_{Leakage of}。

According to another embodiment, not shown, the leakage plug 7 may comprise a valve which is not electrically controlled, but is pushed into the closed position only by a spring whose preload is adjustable before being introduced into the pipe 3. Under liquid pressure, the spring may be pushed to open the valve and allow the leakage plug to leak. The preloading of the spring will (pre-) determine the leakage pressure drop Δ p_{Leakage of}。

According to a further embodiment, the spring may be pushed by a (pulling) force between the cable and the leakage plug, thereby with a preset force (or pressure drop Δ p)_{Leakage of}) And (4) opening.

A first aspect of the present disclosure relates to the use of a leakage plug 7 for installing a cable 1 in two stages. In the first phase, the mode of operation of the installation is typically pulling. In this first mode, the leakage plug (almost) has no leakage, and the cable 1 is pulled due to the pressure on the leakage plug caused by the water pressure.

After a considerable distance or after a number of turns or bends, the pressure is compensated by friction or by traction effects, so that the maximum distance that can be achieved in the first (non-leaking) mode is achieved.

A first aspect of the present disclosure providesA switch from a first mode to a second mode corresponding to a floating technique is presented. For this reason, if a predetermined pressure (hereinafter referred to as "leakage pressure drop" or Δ p) is applied_{Leakage of}) The leakage plug 7 is set to leakage before the leakage plug 7 is inserted. In other words, if the leakage plug 7 is subjected to a pressure difference between its front side and its rear side greater than a predetermined leakage pressure drop Δ p_{Leakage of}The leakage plug 7 will leak.

Thus, the mounting method comprises the steps of: the liquid pressure is increased to force the leakage plug 7 to leak, and then a significantly increased flow is generated, so that the injected liquid generates a drag force along the entire length of the cable 1, allowing further installation of the cable 1 into the conduit 3.

In other words, during the first phase, the liquid flow is limited to a minimum to follow only the leaky plug (in non-leaky mode, so that there is no significant speed difference between the liquid and the cable 1), and once the maximum distance is reached in this non-leaky mode, the pressure is increased to force the leaky plug 7 into a leaky mode during which the flow is significantly increased, thereby generating a drag force along the entire cable 1, thereby increasing the installation distance that can be achieved.

In detail, during the first phase, the liquid flow Φ is defined by the following equation_v：

Wherein:

Φ_vis the supplied pressurized liquid flow rate (m)³/s)，

D_cIs the outer diameter (m) of the cable,

D_dis the inner diameter (m) of the pipe,

v_{cable with a protective layer}Is the velocity (m/s) of the cable into the conduit.

If the leaky plug 7 is in a strictly non-leaking mode, the flow Φ is defined by the following equation_v：

During the second phase, the liquid flow is multiplied by a factor of at least 2, preferably 5, to generate a sufficient drag force. Advantageously, the method may comprise the step of changing the pump supplying the liquid (or adding a second pump): during the first phase, the first pump has a "low" flow rate and a "medium or high" pressure capacity, and during the second phase, the second pump has a "high" flow rate and no reduced pressure capacity.

The leakage plug 7 is set to be at a leakage pressure drop Δ p_{Leakage of}Lower leakage, the leakage pressure drop being chosen to be lower than or equal to the maximum pressure defined taking into account the characteristics of the duct 3. In other words, the pipe 3 has a pressure above which it may be damaged or even cause bursting, and the maximum pressure is defined accordingly. The maximum pressure is chosen to be below the burst pressure of the pipe and may of course be chosen to be safely below the maximum pressure taking into account safety factors. For this reason, the operation temperature and the operation time are also considered.

A second aspect of the present disclosure is the use of a leakage plug 7 in a non-leaking mode or in a leaking mode when the pipe 3 has a non-horizontal trajectory (i.e. the pipe 3 has a non-constant height).

In this case, the invention proposes a specific strategy for laying the cable 1 into the conduit 3, with the leaky plug 7 in non-leaky mode or in leaky mode. In other words, the invention proposes to set a specific supply pressure and/or a specific leakage pressure drop Δ p for the leakage plug 7, depending on the trajectory of the pipe_{Leakage of}。

In particular, in the case of a trajectory as shown in fig. 3, the duct 3 has a height z at a first level₁At a first end 31, and below the height z₁Second height z of₂And a second end 32. However, the first portion of the duct 3 has a positive slope to reach the position x₁A third height z of the vicinity₃(greater than height z)₁) At an intermediate point 33. The pipe 3 then has a negative slope to reach a position at a fourth height z₄(lower than the height z)₁) At the intermediate point 34.

Then, the pipe 3 reaches the position x again₂A height z of the vicinity₃And then reaches position x before reaching second end 32_{Low 3}Is the lowest height z of₅. According to a preferred embodiment of the method the supply of liquid and the introduction of the cable 1 into the conduit 3 is done through the first end having the highest height. In the present case, the highest end is located at what is referred to hereinafter as the height z_supFirst height z of₁At a first end 31 (for supplying liquid).

Hereinafter, the horizontal pressure p_horIs defined as the pressure present in the pipe 3 when the pipe 3 is horizontal. At the liquid supply port, the pressure is equal to the supply pressure p_supAnd decreases according to the viscous flow of the liquid and further decreases after passing through the leakage plug 7, wherein the leakage pressure difference is set to Δ p_{Leakage of}。

For a pipe 3, p filled with water and water to the second end 32_hor(x) Given by:

along a conduit section with a cable

Along the pipe section without cable (behind the leakage plug 7)

Here, x is a coordinate describing a position in the pipe, 0 at the supply port (first end 31) and x at the end of the pipe (second end 32)_{End part}。Δp_viscIs the total viscous pressure drop caused by the flowing liquid:

here,. phi.,. phi._VIs the volume flow rate, D_dIs the diameter of the pipe, D_cIs the diameter of the cable, mu_wIs the dynamic viscosity of a liquid(water 0.0011Pas), p_wIs the density of the liquid (1000 kg/m water)³) And D is_hydroIs the hydraulic diameter.

In the case of a trajectory incline (i.e. a pipe trajectory following a varying height), the hydrostatic pressure p must be taken into account_hydrBecause of the effective pressure p to which the pipe 3 is subjected_effAccording to hydrostatic pressure p_hydrAnd (4) changing.

This can be done by applying a hydrostatic pressure p_hydrAdded to horizontal pressure p_horTo complete. Hydrostatic pressure p relative to the supply port_hydrIs equal to

p_hydr＝-ρ_wg(z_x-z_sup)，

Wherein z is_xAnd z_supIs the height (positive up) at position x and the supply port, respectively. It is easier to define the hydrostatic height function ρ graphically_wg(z_x-z_sup) Then needs to be driven from the horizontal pressure p_horSubtracting the hydrostatic height function to obtain an effective pipe pressure p along the section of pipe having the cable_eff：

p_eff(x)＝p_hor(x)-ρ_wg(z_x-z_sup)

According to a first scenario, fig. 4 shows the hydrostatic height function ρ when installing the cable 1 into the pipe 3 of fig. 3_wg(z_x-z_sup) And horizontal pressure p_hor. Hydrostatic height function ρ_wg(z_x-z_sup) Having the same profile as the trajectory of the pipe 3. Effective pressure p along a conduit section with a cable_effCan simply pass through the horizontal pressure p_horCurve of (d) and hydrostatic height function ρ_wg(z_x-z_sup) Is obtained by a vertical distance between the two, the effective pressure p_effAt point x, is the maximum of_{Low 3}And at position x_{End part}Is zero at the second end 32 because that end is at atmospheric pressure.

Note that: while the leakage plug 7 is still inside the pipe 3, the volume in front of the leakage plug 7 is at atmospheric pressure; when the leakage plug 7 comes out, the whole situation changes, since the liquid can freely leak.

Note also that from the latter case, the boundary condition Δ p may be calculated_visc(and the flow rates derived therefrom):

Δp_visc＝p_sup-ρ_wg(z₂-z_sup)-Δp_{leakage of}

According to the invention, the supply pressure p_supAnd the leakage pressure deltap over the entire leakage plug 7_{Leakage of}Are all set so that the horizontal pressure p_horAlways in still water height function ρ_wg(z_x-z_sup) The method comprises the following steps:

p_eff(x) Not less than 0 or p_hor(x)≥ρ_wg(z_x-z_sup) (1)

At position x_{Low 3}In the lowest point (right-hand depression in the height distribution) of (a), the maximum pressure p is indicated_max. This pressure must not be higher than the maximum pressure that the pipe 3 can withstand (this maximum pressure can be chosen as its normal use pressure or as a burst pressure with a safety factor taking into account the operating temperature and/or the installation time). In general, all positions in the pipeline apply:

p_eff(x)≤p_maxor p_hor(x)-ρ_wg(z_x-z_sup)≤p_max(2)

Note that when the recess is at "depth" h_Depressions(on both sides) to result in ρ_wgh_DepressionsGreater than the maximum pressure p_maxThen, equation (2) cannot be satisfied.

Also note that the supply pressure p at the inlet_supIs chosen just enough to make the horizontal pressure p_horAt position x₂Is related to hydrostatic pressure p_hydrTangent or just at hydrostatic pressure p_hydrTo ensure that the loss of viscosity does not prevent the leakage plug 7 from passing this point.

FIG. 5 shows the flow through the leakage plug 7_VpAs a function of the position x of the leak plug 7 in the pipe 3. The height distribution of the pipe 3 is given by reference to the dotted line toThe different scales show the height z.

The different positions of the leakage plug 7 are indicated in capital letters. Until A, the pressure on the leakage plug 7 is less than the set maximum pressure, so that the leakage plug 7 is in non-leakage mode, such that the flow phi through the leakage plug 7_VAlmost zero.

Then, when point a is reached, the leakage plug 7 opens and rapidly produces a large flow Φ_VpUntil when the leakage plug 7 first contacts the bottom of the depression in the pipe (position X)₁) Maximum flow at A1_VpUntil now, when the leakage plug 7 follows the contour of the depression in the pipe 3 up to the point a2, the flow rate Φ_VThere is little reduction.

Then, when the depression in the conduit 3 starts to be filled (in front of the leakage plug 7), the flow rate Φ_VpDecreases rapidly until it is zero at a 3. The position of a2 and how quickly the flow rate decreases (position of A3) depends on the maximum flow rate through the conduit 3 and the volume of the conduit 3 in the depression. Next, as the height z increases, the flow rate Φ_VAgain remaining at zero for a period of time until position B of the leaky plug 7.

Then, the leakage plug 7 opens again and the flow Φ_VAnd (4) increasing. At the arrival C, in the steeper part of the pipeline trajectory, the flow phi_VpIncreasing more rapidly. At arrival D, the flow rate Φ_VpReaches its maximum value until the leakage plug 7 reaches the outlet of the pipe 3, i.e. X_{End part}Up to point E.

According to a second scenario, fig. 6 shows the hydrostatic height function ρ when installing the cable 1 into the pipe 3 of fig. 3_wg(z_x-z_sup) And horizontal pressure p_hor. For the following specific cases: p is a radical of_supAnd Δ p_{Leakage of}Is set so that the effective pressure p_effOnly two depressions in the height distribution of the pipe track are reached (at position x)₁At and position x_{Low 3}At) maximum pressure p_maxThis is plotted. Equations (1) and (2) are still observed. For this purpose, the pressure p at the supply port_supIs set to a pressure slightly higher than that in FIG. 4, the wholeLeakage pressure Δ p on the leakage plug_{Leakage of}Is set to be small and the viscous pressure drop deltap_viscWith a consequent greater (i.e. greater flow rate). In this case, the operating conditions are maximized so that the installation of the cable 1 is faster than in the condition of fig. 4.

According to a third scenario, fig. 7 shows the hydrostatic height function ρ when installing the cable 1 into the pipe 3 of fig. 3_wg(z_x-z_sup) And horizontal pressure p_hor. For the following specific cases: supply pressure p_supAnd the leakage pressure deltap across the leakage plug_{Leakage of}Is set so that the effective pressure p_effOnly the left-hand depression (at position x) in the height distribution of the pipe track is reached₁And x₂Maximum pressure p in (b) of_maxThis is plotted. Equations (1) and (2) are still respected. Now, the pressure p at the supply port_supIs set to a pressure still slightly higher than in fig. 4, the leakage pressure Δ p across the leakage plug_{Leakage of}Is set to be small and the viscous pressure drop deltap_viscWith a consequent greater (i.e. greater flow rate).

Note that the supply pressure p can also be set_supAnd the leakage pressure deltap across the leakage plug_{Leakage of}So that the viscous pressure drop Δ p_viscMinimized (i.e., less traffic).

According to a fourth scenario, fig. 8 shows the hydrostatic height function ρ when installing the cable 1 into the pipe 3 of fig. 3_wg(z_x-z_sup) And horizontal pressure p_hor. Pressure p at the supply port_supAnd a leakage pressure difference Δ p across the leakage plug 7_{Leakage of}Is set the same as in fig. 4, but now the leak plug 7 is positioned in the duct 3 in the following position: effective pressure p_effJust reaching into the local left side depression (position x)₁-x₂At) maximum pressure p_maxThe position of (a). Here the viscous pressure drop Δ p_viscWill be less than the viscous pressure drop in fig. 4. In this case, the pipe 3 downstream of the leakage plug 3 will no longer be filled with liquid (here water), since a steep slope in this downhill area will require more than a portion of the pipe 3 filled with the cable 1 and liquidThe flow rate supplied in the branch is larger. The effective pressure p immediately after the leakage plug 7 is then_effWill be zero. Horizontal pressure p downstream of the leakage plug 7_horIndicating that the water flow is not filling the pipe and the effective pressure p during the first part_effIs zero. Then, a horizontal pressure p is reached_horLine to hydrostatic height function ρ_wg(z_x-z_sup) The point where the lines meet, since here the pipe 3 is again filled with liquid and the effective pressure p_effOr may become non-zero again. If the leakage plug 7 starts to leak (and there is no liquid in the pipe 3 downstream of the leakage plug 7), there is no effect on the liquid-filled portion of the (associated) cable 1 and pipe 3 (upstream of the leakage plug 7).

In fig. 9, the leak plug 7 is closer to the supply port 31 than in fig. 8. Now, the setting of fig. 4 can no longer be maintained. In this case, the leakage pressure difference Δ p of the leakage plug 7_{Leakage of}Is set to be small. In fig. 10 the position of the leakage plug 7 is the same as in fig. 9, but now the setting of the leakage plug 7 is not changed, but the pressure p at the supply port is reduced_supAgain such that equation (2) is satisfied and the maximum pressure p is not exceeded_max. In this case, the pressure at which the leak plug 7 starts to leak has not been reached (non-leakage mode). Thus, there is no flow over the pipe 3 and a viscous pressure drop Δ p_viscIs zero.

However, once the effective pressure equals the maximum pressure p_maxThe leakage plug 7 will leak to avoid any damage to the pipe 3.

It will, of course, be understood that obvious improvements and/or modifications may be effected by those skilled in the art, while remaining within the scope of the invention as defined by the appended claims.