CN103398218B - Construction and protection method for long-distance parallel subsea pipeline - Google Patents

Abstract

The invention relates to a construction and protection method for a long-distance parallel subsea pipeline. The method comprises the steps of comparative analysis on original pipeline design material and a research report, analysis on pipeline parallel laying risk points, analysis on a pipe-laying ship mooring system, analysis on an anchor cable catenary and rendering and filed conduction of a construction anchor settling drawing. By means of research on the anchor cable catenary, with combination of a calculation result, the construction anchor settling drawing is rendered according to the engineering ship anchor settling theory, and the stress situation of each anchor in the anchor settling state of a ship under the extreme working condition is counted through relative software. The method has the advantages of economical, efficient, free of pollution, strong in operability and the like. In addition, the construction requirement is met.

Description

A kind of long distance parallel subsea pipeline construction guard method

Technical field

The present invention relates to the technical field of undersea pipe-laying, be specifically related to a kind of long distance parallel subsea pipeline construction guard method.

Background technique

Along with offshore oil and gas field exploitation is constantly to deep layer and frontier expansion, offshore platform process treating flow process more and more simplifies, increasing submerged pipeline is used, inevitably there will be pipeline installation and existing pipeline parallel phenomenon in pipe installation process, the present invention for this reason problem provides simple and practical operating method.

At present, domestic and international specification does not have corresponding specification to long distance parallel pipeline pipe laying construction resist technology, domestic long distance parallel pipeline construction precedent, and only engineering ship rear anchor hawser crossover line in place arranges floating drum and do not carry out moving anchor job execution.

For above situation; we are on the basis of consulting data at home and abroad; by large component analysis; develop the method for a set of satisfied long distance parallel subsea pipeline construction protection; the method is based on catenary equation; investigated long distance parallel subsea pipeline cloth anchor method, achieve the control to pipe laying construction cloth anchor, solve a difficult problem for long distance parallel subsea pipeline protection.The method proposes the solution of long distance parallel subsea pipeline construction first, the safety of pipeline during having ensured original pipeline operation.Breach traditional buoy anchoring system mode first, distance parallel subsea pipeline resist technology successful Application will be grown in the branch line submarine pipeline state key project financing of the second west to east gas pipeline project Hong Kong.

The method has the features such as economy, efficient, pollution-free, strong operability, meets construction requirement.

Summary of the invention

For above-mentioned deficiency of the prior art, the present invention seeks to based on catenary equation, investigated long distance parallel subsea pipeline cloth anchor method, achieve the control to pipe laying construction cloth anchor, solve a difficult problem for long distance parallel subsea pipeline protection.The method proposes the solution of long distance parallel subsea pipeline construction first, the safety of pipeline during having ensured original pipeline operation.Consider controlled investment, reduction of erection time, facilitate the aspect factors such as site operation, form the technological scheme being applicable to long distance parallel subsea pipeline construction protection.

In order to realize foregoing invention object, this application provides following technological scheme:

(1) original pipeline design data and survey report comparative analysis

By to original pipeline design data and the pipeline route survey report adopting GeoPulse sub-bottom profiler/pipeline instrument, analyze the present routing condition of pipeline, pipe top buried depth and cover soil property type.

(2) pipeline parallel lays risk point analysis

Risk sources maximum in construction operation in the anchor of operation boats and ships and anchor hawser on the impact of pipeline.Because long distance is parallel, pipe laying barge construction is a dynamic process, often complete an extra large pipe job execution, need to carry out folding and unfolding anchor hawser reach pipe laying barge, and there is rising of cycle and to cast anchor operation, anchor hawser crosses over original pipeline, there is the scraping to original pipeline and sawing risk, works operation of casting anchor and there is this risk equally.

(3) pipe laying barge mooring system is analyzed

By to the research of self mooring system of construction operation pipe laying barge, specify each parameter of mooring system.Comprise anchor weight, anchor hawser model, anchor hawser length and windlass maximum pull etc.

Adopt anchoring analytical technology, check cloth anchor scheme and whether meet mechanical equilibrium requirement; Specify the mechanics projecting point of each cloth anchor scheme, the cloth anchor work of accurate instruction practice of construction, thus avoid the destruction that the mechanical structure of the cloth anchor schematic design making of mistake causes to extra large pipe.

(4) mooring line catenary analysis

Boats and ships are when casting anchor mooring, and anchor cable is stretched wire state.Anchor hawser wire rope has good flexibility and uniform quality, and therefore single anchor chain or the anchor cable of wire rope can regard as simple cautionary suspension line, is below catenary formula.

$y=a[\sec \mathrm{\α}\left(\mathrm{ch}\frac{x}{a}\right)-1]+\mathrm{tg\α}\·\mathrm{sh}\frac{x}{a}=\frac{R}{w}[\frac{1}{\cos \mathrm{\α}}(\frac{e^{\frac{x\·w}{R}}+e^{\frac{-x\·w}{R}}}{2}-1)+\mathrm{tg}\·\frac{e^{\frac{x\·w}{R}}+e^{\frac{-x\·w}{R}}}{2}]---\left(1\right)$

The y depth of water in formula, m;

R effect external force aboard ship, t;

X anchoring point to the horizontal equivalent of chaining point, m;

A weighs anchor angle, °;

W every meter chain weight, t/m

Assuming that the anchor cable hitching boats and ships to be an intensity very large, and do not have ponderable anchor cable.The pulling force H acting on boats and ships is substantially horizontal, and this power acts on anchor by anchor cable.When anchor cable tension and when not dragging of anchor, horizontal pull H0 and the environmental forces H of anchor balance, i.e. H0=H.Equilibrium of forces as shown in Figure 1.If the angle theta of the horizontal force H0 at anchor point O place, vertical force V0, tension force T0 and tension force and horizontal force ₀, the vertical force V of hawse pipe outlet port A, tension force T, and the angle theta of tension force and horizontal force.Following equation is had according to equilibrium of forces:

V ₀=H ₀tanθ ₀=Htanθ ₀(2)

$T_0=\sqrt{{H_0}^2+{V_0}^2}=H\sec {\mathrm{\θ}}_0---\left(3\right)$

If anchor cable is ponderable, anchor cable linear mass load is in the seawater w, and the length of anchor cable (catenary) is the horizontal equivalent of s, A to O is x, and vertical distance (depth of water) is z.

$\frac{w}{H}s=\tan \mathrm{\θ}-\tan {\mathrm{\θ}}_0---\left(4\right)$

$\frac{w}{H}z=\sec \mathrm{\θ}-\sec {\mathrm{\θ}}_0---\left(5\right)$

$\frac{w}{H}x=\ln \left(\frac{\sec \mathrm{\θ}+\tan \mathrm{\θ}}{\sec {\mathrm{\θ}}_0+\tan {\mathrm{\θ}}_0}\right)---\left(6\right)$

Simulated program based on VB programming has the features such as friendly interface, computational speed be fast, and is easy to grasp.The program adopted is that VB writes.

Program solution step:

Determine initial catenary parameter a (each anchor cable is the same).

Set up the newton iteration formula of each anchor cable about a value.

Carry out iteration.

Determine whether requirement, meet, terminate to calculate; Otherwise, increase iterations, until full

Till foot condition.

(5) the cloth anchor figure that constructs draws and field conduct

According to cloth anchor principle, draw cloth anchor figure, crossover line side, anchor point and pipeline safety distance will consider to slip anchor distance, ensure to be greater than more than 100 meters.Arrange the indication buoy of three color different interval 30 meters every 200 meters above original pipeline.Need the tension force of pre-imputation during site operation cloth anchor, cast anchor operation time guarantee that anchor to be placed on safely on anchor boat deck and fixing, avoids landing from anchor boat.Work the shape of casting anchor by special messenger's charge of overseeing anchor hawser stressing conditions and anchor hawser between operational period.

Beneficial effect:

1, for first domestic.Parallel subsea pipeline is constructed, and pipeline specifications is without clear stipulaties and recommend way, and the construction of long distance parallel subsea pipeline, at home and abroad all beyond example;

2, economic, efficient, strong operability can effectively solve engineering place marine area function zoning complexity, boats and ships frequent activity, program practice sternly, the tight requirement of implementing plan duration.

3, long distance parallel subsea pipeline construction protection, constructing forms danger to primary tube line, moves anchor Job Operations improper, very easily works the mischief to original pipeline, produce immeasurable consequence in construction.The program can meet the feature that this project program practice is tight, the implementing plan duration is tight, meets field engineering requirement.

4, long distance parallel subsea pipeline construction guard method, can achieve good effect, can solve the actual conditions of the construction of long distance parallel pipeline and duration anxiety in engineering.Compare conventional scheme, reduce investment outlay, produce obvious economic benefit.

5, long distance parallel subsea pipeline construction guard method, at home and abroad all beyond example, applies first, successfully solves the difficult problem with city, precipice pipeline parallel 6.11 kilometers in the branch line submarine pipeline engineering of the second west to east gas pipeline project Hong Kong.Therefore, the breakthrough of this technology, has great importance to the technical barrier etc. of China's parallel pipeline construction protection that fills the domestic gaps, solves.Construction for submarine pipeline of the same trade provides strong reference reference value.

Accompanying drawing explanation

Fig. 1 basis cloth anchor figure

The phase diagram of Fig. 2 anchor hawser stretched wire

Fig. 3 anchor hawser stretched wire state free-body diagram

Fig. 4 program computation interface

Fig. 5 indication buoy schematic diagram

Fig. 6 straight line section of walking abreast cloth anchor figure

Fig. 7 camber line section of walking abreast cloth anchor figure

Fig. 8 progressive section of cloth anchor figure

Embodiment

Long distance parallel subsea pipeline arrangement and method for construction:

By presetting pretensioning, going out different water depth anchor hawser according to catenary program computation and touching mud point overhanging horizontal length, guaranteeing that anchor hawser touches mud point outside original pipeline, to ensure that anchor hawser does not contact with pipeline.

Catenary equation program calculation data

Three kinds of operating modes for pipeline parallel exists:

The pipeline straight line section of walking abreast;

The pipeline curve section of walking abreast;

Progressive section of pipeline.

(1) the pipeline straight line section of walking abreast construction

Go out to cross over according to program computation the distance that anchor hawser touches the original pipeline of mud point.By controlling pipe laying barge pretensioning, when ensureing that pipe laying barge moves, anchor hawser touches mud point outside precipice municipal administration line, ensures that anchor hawser is above pipeline, does not contact with pipeline.At anchor point reasonable Arrangement anchor point monitoring ship, the moment monitoring position of anchor point, anchor hawser length, each anchor are relative to the angle of pipe laying barge.

(2) the pipeline curve section of walking abreast construction.

Go out to cross over anchor hawser by catenary program computation and touch mud point distance, reasonable cloth anchor, control pipe laying barge anchor hawser tension variation realizes anchor hawser and touches mud point outside original pipeline, avoids the contact of anchor hawser and pipeline.At anchor point reasonable Arrangement anchor point monitoring ship, the moment monitoring position of anchor point, anchor hawser length, each anchor are relative to the angle of pipe laying barge.

(3) progressive section of pipeline construction.

Go out to cross over anchor hawser by catenary program computation and touch mud point distance, reasonable cloth anchor, control pipe laying barge anchor hawser tension variation realizes anchor hawser and touches mud point outside original pipeline, avoids the contact of anchor hawser and pipeline.At anchor point reasonable Arrangement anchor point monitoring ship, the moment monitoring position of anchor point, anchor hawser length, each anchor are relative to the angle of pipe laying barge.

Last it is noted that obviously, above-described embodiment is only for example of the present invention is clearly described, and the restriction not to mode of execution.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here exhaustive without the need to also giving all mode of executions.And thus the apparent change of amplifying out or variation be still among protection scope of the present invention.

Claims (3)

1. a long distance parallel subsea pipeline construction guard method, is characterized in that, comprise the steps:

Step one, original pipeline design data and survey report comparative analysis,

By to original pipeline design data and the pipeline route survey report adopting GeoPulse sub-bottom profiler or pipeline instrument, analyze the present routing condition of pipeline, pipe top buried depth and cover soil property type;

Step 2, pipeline parallel lay risk point analysis,

Risk sources maximum in construction operation in the anchor of operation boats and ships and anchor hawser on the impact of pipeline;

Step 3, pipe laying barge mooring system are analyzed,

By to the research of self mooring system of construction operation pipe laying barge, specify each parameter of mooring system, comprise anchor weight, anchor hawser model, anchor hawser length and windlass maximum pull;

Step 4, mooring line catenary analysis,

Boats and ships are after casting anchor, and anchor hawser is stretched wire state, and anchor chain or wire rope have good flexibility and uniform quality, and single anchor chain or the anchor hawser of wire rope regard as simple cautionary suspension line;

Step 5, construction cloth anchor figure draw and field conduct,

By to mooring line catenary research, in conjunction with result of calculation, according to engineering ship cloth anchor point theory, draw construction cloth anchor figure, and adjust this cloth anchor-shaped state of boats and ships each anchor hawser stressing conditions under extreme operating condition by related software.

2. method according to claim 1, it is characterized in that: self mooring system of the pipe laying barge in described step 3 is analyzed, by to the research of self mooring system of construction operation pipe laying barge, specify each parameter of mooring system, comprise anchor weight, anchor hawser model, anchor hawser length and windlass maximum pull.

3. method according to claim 1, is characterized in that: the mooring line catenary analysis in described step 4, and boats and ships are after cloth anchor, anchor hawser is stretched wire state, single anchor hawser is considered as simple catenary, according to catenary formula, passes through method of iteration, according to construction depth of water situation, preset different tension force, calculate engineering ship in same depth of water situation, go out mud point is touched in chain hole horizontal equivalent to anchor hawser, selection level distance is greater than the spacing of pipeline parallel, determines pretensioning size.