KR101681710B1 - Semi-submersible marine structure - Google Patents

Semi-submersible marine structure Download PDF

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Publication number
KR101681710B1
KR101681710B1 KR1020120012451A KR20120012451A KR101681710B1 KR 101681710 B1 KR101681710 B1 KR 101681710B1 KR 1020120012451 A KR1020120012451 A KR 1020120012451A KR 20120012451 A KR20120012451 A KR 20120012451A KR 101681710 B1 KR101681710 B1 KR 101681710B1
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KR
South Korea
Prior art keywords
semi
pontoon
transverse vibration
vibration reducing
columns
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KR1020120012451A
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Korean (ko)
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KR20130091148A (en
Inventor
김용수
박병원
김대웅
김덕수
김철현
남종오
Original Assignee
대우조선해양 주식회사
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/06—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water
    • B63B2039/067—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water effecting motion dampening by means of fixed or movable resistance bodies, e.g. by bilge keels

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Earth Drilling (AREA)

Abstract

A semi-submergible offshore structure is disclosed. The semi-submergible offshore structure of the present invention comprises: a pontoon provided with a plurality of columns supporting a deck; And a lateral rocking relief portion disposed at an upper portion of the pontoon and disposed between the plurality of columns to cancel an excitation force generated by waves to reduce lateral rocking.

Description

{SEMI-SUBMERSIBLE MARINE STRUCTURE}

The present invention relates to semi-submergible offshore structures, and more particularly, to semi-submerged offshore structures that perform drilling for oilfield development in the ocean.

The depth of the oil field currently under development is gradually shifting to deep sea. In order to develop oilfields, drilling operations should be preceded by confirmation of the oil stores, and the depth of drilling is also shifting to deep sea due to the trend of oil field development.

Drilling-ship, drilling-rig, jack-up, and drilling-barge are examples of typical offshore structures for drilling. Among these, Drill-ship and Drilling-Rig are available for deep drilling. Drill-ship is a ship-type drill ship, which has the advantage of long-term operation without the help of a supply vessel because of the large loading space. However, due to the disadvantage of poor performance due to the ship type, the input is limited in the sea area where the sea environmental load due to waves and the like is high.

Drilling-Rig is also called semi-submersible. Semi-submersible is composed of column and pontoon, and it has good merit because of small repair area. Therefore, it is possible to input even in the sea area where the marine environmental load is relatively high, and it is putting a lot of effort into the development of the deep sea oil field.

However, according to recent research and solid line measurement results, the stability and efficiency of the drilling work are lowered due to the inclination of the semi-submersible while maintaining a constant angle during the work or the long swaying motion of the long period.

Korean Patent Registration No. 10-1039371 (Holding Company, Ltd.) 2011. 05. 31.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a semi-submergible offshore structure capable of improving stability and efficiency of a drilling operation by preventing slanting at a certain angle in a marine environment or preventing long-period swaying.

According to an aspect of the present invention, there is provided a pontoon in which a plurality of columns for supporting decks are provided; And a transverse vibration reducing portion provided on the upper side of the pontoon and disposed between the plurality of columns to cancel an excitation force generated by waves to reduce rolling motion.

The Rolling may be a 2 nd order Roll is caused by the 2 nd order wave component of the field generated due to the overlap of the wave acting on the semi-submersible offshore structure period.

The transverse rocking reduction unit may include a lateral rocking reduction member protruding toward the deck in an upper portion of the pontoon.

The transverse motion reducing member may be provided to be foldable on the pontoons.

The transverse motion reducing member may be a partition wall vertically provided on the upper surface of the pontoon.

The transverse vibration reducing member may be a partition wall inclined at an acute angle with respect to the deck direction with respect to the bottom of the upper surface of the pontoon.

The transverse motion reducing member may have a rectangular shape, a trapezoidal shape, a triangular shape, or a polygonal shape including a rectangular shape whose upper portion is an ellipse.

The columns may be spaced apart from each other, and the transverse vibration reducing members may be spaced apart from each other at a central portion of the pontoons with respect to a longitudinal direction of the pontoons.

The pair of horizontal rocking reduction members may be disposed at regular intervals.

Wherein the lateral rocking reduction member is provided at a height lower than a height of the center of the column with respect to a height from an upper surface portion of the pontoon to a bottom surface portion of the deck, It can be exposed above the sea level based on the self-weight draft of the offshore structure.

The transverse vibration reducing portion may further include a reinforcing member provided on the pontoon to reinforce the transverse vibration reducing member.

The reinforcing member may be provided on the pontoon so as to be foldable.

According to another embodiment of the present invention, there is provided a semi-submergible offshore structure including a plurality of columns supporting a deck and a pontoon on which the plurality of columns are provided, And a transverse vibration reducing unit disposed between the plurality of columns for canceling an excitation force generated by waves to reduce rolling motion.

Embodiments of the present invention can improve stability and efficiency of a drilling operation by preventing a semi-submergible offshore structure from being inclined at a certain angle from the sea or causing long-period swaying due to a transverse vibration reducing portion provided in a pontoon have.

1 is a schematic view of a semi-submergible offshore structure according to an embodiment of the present invention.
2 is a graph illustrating a resonant period of a semi-submergible offshore structure according to an embodiment of the present invention.
FIG. 3 is a graph showing a long period and an inclination of a semi-submergible offshore structure in a model test of a semi-submergible offshore structure according to an embodiment of the prior art.
4 is a graph showing a 2 nd order wave of a long period due to superposition of waves in a semi-submergible offshore structure according to an embodiment of the related art.
Figure 5 is a graph showing the 2 nd order Rolling phenomenon occurs in semi-submersible offshore structure in accordance with one embodiment of the prior art.
FIG. 6 is a graph illustrating a 2 nd order lateral rocking phenomenon occurring in a semi-submergible offshore structure according to an embodiment of the present invention.
Fig. 7 is an enlarged view of the area "A" in Fig.
8 is a view showing an operating state of the lateral movement reducing section shown in FIG.
9 to 12 are views schematically showing a semi-submergible offshore structure according to another embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

2 is a graph showing a resonance period of a semi-submergible offshore structure according to an embodiment of the present invention, and FIG. 3 is a graph showing a resonance period of a semi-submergible offshore structure according to an embodiment of the present invention. FIG. 4 is a graph showing a long period and an inclination of a semi-submergible offshore structure in a model test of a semi-submergible offshore structure according to an embodiment of the prior art. FIG. is a graph showing the 2 nd order of the long-wave occurs due to superposition of waves in a marine structure, Figure 5 is a graph showing the 2 nd order Rolling phenomenon occurs in semi-submersible offshore structure in accordance with one embodiment of the prior art, Fig. 6 is a graph showing a 2 nd order lateral rocking phenomenon occurring in a semi-submergible offshore structure according to an embodiment of the present invention, and Fig. 7 is an enlarged view And Fig. 8 is a view showing an operating state of the lateral movement reducing section shown in Fig.

As shown in these drawings, the semi-submergible offshore structure 1 according to the present embodiment includes a pontoon 100 having a plurality of columns 200 for supporting a deck D, And a transverse vibration reducing part 300 provided at an upper side of the piezoelectric vibrator 100 and disposed between the plurality of columns 200 to cancel the excitation force generated by the waves to reduce rolling motion.

Prior to the description of this embodiment, the description of the cause of the 2 nd order rolling sway phenomenon by the superposition of waves in the marine environment and the meaning of the 2 nd order rolling sway phenomenon are defined.

The semi-submerged structure used for crude oil drilling in the ocean includes a horizontal pontoon 100 immersed in the sea surface and a column 200 installed vertically on the upper side of the pontoon 100. This semi-submerged structure has a smaller repair area (area of cross section cut along the waterline) than conventional vessels because the column is in contact with the water plane.

As the repair area becomes smaller, the restoring force in the vertical direction and the restoring moment in the lateral direction become smaller, so that the resonance period in the corresponding direction becomes longer. Thus, the semi-submergible structure has a resonance period of about 50 seconds or more do.

Considering that a typical ocean wave period does not exceed 20 seconds, the vertical and transverse resonance periods of a semi-submersible structure are significantly distant from the wave period. Therefore, there is no possibility that the semi-submergible structure will have a large behavior due to the resonance phenomenon caused by overlapping the self-resonant period and the wave period of the semi-submerged structure.

However, according to the recent survey, the semi - submerged structure tilts at a constant angle in a general marine environment, or the semi - submerged structure has a long - period swaying phenomenon. A long period generally means a cycle having a period of 50 seconds or more.

According to a recent study this phenomenon was found to be 2 nd order Roll is the cause of the semi-submersible structure. This can be seen from the data based on the model of the semi-submergible structure. As a result of experiments under constant wave conditions based on the model of the semi-submergible structure, the longitudinal semi-swaying and tilting phenomena similar to the solid line measurement occurred in the model of the semi-submergible structure, as shown in FIG.

This half is caused by the long-cycle 2 nd order wave component of which may result from a superposition of the waves acting on the submersible structure, this embodiment has the lateral shake of the long to the semi-submersible structure inclined or semi-submersible structure by such a phenomenon The occurrence of the phenomenon is defined as a 2 nd order transient phenomenon.

Between the vertical and the orbital period is 2 nd order caused by the overlap of the semi-submersible structure with the wave, when consider that having at least 50 seconds the long-wave component of the Roll of the generally semi-submersible structure (see Fig. 4) Resonance phenomenon can be expected.

The efficiency of the present embodiment can be found through numerical calculation using numerical calculation conditions set the same as experimental conditions. In an embodiment of the prior art, as shown in FIG. 5, the semi-submergible structure tilts in the same manner as in the numerical calculation experiment, and the 2 nd order lateral rocking phenomenon can be predicted through numerical calculation.

However, this embodiment is as shown in Figure 6 by the Rolling reduction section 300 provided in the pontoon 100, and, had significantly reduced skew is by one embodiment of the prior art, resulting in 2 nd order It can be confirmed that the rolling phenomenon is remarkably reduced.

The podoon 100 and the column 200 of the semi-submergible offshore structure 1 according to the present embodiment and the transverse vibration reducing section 300 provided on the pontoon 100 will now be described in detail.

The pontoon 100 is slightly submerged in the sea surface when the offshore structure is moving in the sea, but when the drilling operation is performed at a predetermined position, the entire pontoon 100 is kept submerged below sea level.

8, the pair of pontoons 100 may be spaced apart in parallel. Although not shown in the pontoons 100, various types of pontoons 100, such as a main engine unit, a ballast, a fuel tank, Equipment and equipment necessary for operation and cargo may be loaded.

1, a lower end of the column 200 is connected to an upper portion of the pontoon 100 and an upper end of the column 200 is connected to a bottom portion of the deck D to support the deck D, In an embodiment, the columns 200 may be spaced apart from one another in a single pontoon 100, or may be provided in a plurality of columns.

1, the transverse vibration reducing section 300 is provided on the upper side of the pontoons 100 between the plurality of columns 200, and is provided with a 2 nd order wave component acting on the ocean structure according to the present embodiment. It prevents the generation of 2 nd order fluctuation phenomenon by canceling the excitation force by 2 nd order wave component.

Specifically, 2 nd order wave component of the long period caused by the overlap of the wave that is, Fig. 2 nd order wave component on the basis of 8 delivered from left to right are - Rolling reduction unit 300 provided in the left portion of the pontoon (100) It is not possible to maintain the 2 nd order wave component.

As a result, the generation of the 2 nd order wave component is suppressed, and the excitation force due to the 2 nd order wave component is canceled by colliding with the transverse vibration reducing section 300, so that the 2 nd order transverse fluctuation phenomenon is significantly reduced.

In the present embodiment, as shown in Fig. 8, the transverse vibration reducing section 300 may be provided such that a pair of the transverse vibration reducing section 300 is disposed in each pontoon 100 between the pair of columns 200, A plurality of transverse vibration reducing sections 300 may be provided, which are disposed between the first and second transverse vibration reducing sections 200.

1, the transverse vibration reducing section 300 includes a transverse vibration reducing section 300 and a transverse vibration reducing section 300. The transverse vibration reducing section 300 includes a transverse vibration reducing section 300, A vibration reducing member 310 and a reinforcing member 320 provided on the pontoon 100 to reinforce the lateral vibration reducing member 310.

1 and 8, the horizontal movement reducing member 310 of the horizontal movement reducing section 300 may be a partition wall provided between the pair of columns 200. In the present embodiment, reducing member 310 pair between a pair of columns 200 to offset the 2 nd order wave component of the long transmitted from the left and right of the column 200 on the basis of Fig. 8 in the left and right sides of the column (200) A separation can be provided.

In addition, each from the center of the Roll-reducing member 310 to be evenly offset the 2 nd order wave components of the long, as shown in Figure 1, the pontoon 100 pontoon 100 relative to the longitudinal direction of the One pair may be arranged at equal intervals in the direction of the column 200 of FIG.

Furthermore, the Rolling reduction member 310 includes a 2 nd order for effective cancellation of the wave components, as shown in Figure 1, doedoe provided at a lower height than the center height of the column 200, a side portion of the long this embodiment Can be exposed above sea level based on the self-weight draft of the semi-submergible offshore structure (1) according to the example. The height of the central portion of the column 200 in the present embodiment is based on the height from the upper surface portion of the pontoon 100 to the bottom portion of the deck D. [

7, the horizontal movement reducing member 310 may have a rectangular shape, and may have a width corresponding to the horizontal width of the pontoon 100 in the present embodiment.

In particular, in the present embodiment, the transverse vibration reducing member 310 may be provided so as to be able to be folded on the pontoon 100 to reduce frictional resistance with sea water in the sea surface area when moving from sea to sea. Although the folding means of the horizontal movement reducing member 310 is not shown in the present embodiment, a pivot shaft is provided on the upper surface of the pontoon 100 and the lower portion of the horizontal movement reducing member 310 is hingedly coupled to the pivot shaft Method or the like.

1 and 7, the reinforcement member 320 of the transverse vibration reducing portion 300 is provided on the upper side of the pontoon 100 to reinforce the transverse vibration reducing member 310, The reinforcing member 320 may be manufactured in the form of a reinforcing piece 321 or a truss 322. [

Also, in this embodiment, the reinforcing member 320 can be foldably provided on the upper side of the pontoons 100 by the folding means such as the above-described horizontal movement reducing member 310 described above.

9 to 12 are views schematically showing semi-submergible offshore structures 1a to 1d according to another embodiment of the present invention.

In the case of the above-described embodiment, the horizontal movement reducing member 310 is formed in a rectangular shape and provided perpendicular to the pontoon 100 (see FIG. 7). 9 to 11, the transverse vibration reducing members 310a to 310d of the semi-submergible offshore structures 1a to 1d according to another embodiment of the present invention are designed so that the sea environment, that is, the wave height, And can have various shapes.

In this embodiment, the horizontal movement reducing members 310a to 310d have a trapezoidal shape as shown in Fig. 9, a triangular shape as shown in Fig. 10, and a rectangular shape having an oval shape as the upper side as shown in Fig. Etc., and can have various heights.

12, the horizontal movement reducing members 310a to 310d are inclined in the range of an acute angle with respect to the deck D with respect to the bottom of the upper surface portion of the pontoon 100, .

As described above, in the semi-submergible offshore structure according to the present embodiment, the semi-submergible offshore structure is prevented from being inclined at a certain angle from the sea due to the transverse vibration reducing portion provided in the pontoon, There is an advantage that the stability and efficiency of the drilling operation can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

1,1a ~ 1d: semi-submergible offshore structure 100: pontoon
200: column 300: transverse vibration reducing section
310, 310a to 310d: transverse vibration reducing member 320: reinforcing member
D: Deck

Claims (14)

A plurality of columns supporting the deck;
A pontoon on which the plurality of columns are provided; And
A cyclic component disposed in the upper portion of the pontoon and disposed between the plurality of columns and having a low frequency of at least 50 seconds in which a large area acts longitudinally on the semi-submergible offshore structure, And one or more transverse vibration reducing portions positioned to face the 2nd order wave component causing the transverse vibration of the structure,
The columns are spaced apart from each other,
In order to reduce the rolling sway by canceling the excitation force of the 2nd order wave and the 2nd order wave applied to the semi-submergible offshore structure,
And a lateral rocking relief member which is a partition wall protruding obliquely in a vertical or acute angle in the direction of the deck at an upper portion of the pontoon,
The transverse vibration reducing members are spaced at equal intervals from each other at a central portion of the pontoons with respect to a longitudinal direction of the pontoons and are spaced apart from each other at a central portion of the pontoons with respect to a height from a top surface portion of the pontoons to a bottom surface portion of the deck, Wherein the upper side region is exposed on the sea surface based on the self-weight draft of the semi-submergible offshore structure and is provided in a lateral width corresponding to the lateral width in the longitudinal direction of the pontoons,
Characterized in that the transverse vibration reducing member varies the cycle of the 2nd order wave component transmitted from the one column to the other column between the pair of columns and the column. delete delete The method according to claim 1,
Wherein the transverse vibration reducing member is provided to be foldable on the pontoon. delete delete The method of claim 4,
Wherein the transverse vibration reducing member has a polygonal shape including a quadrangular shape, a trapezoidal shape, a triangular shape, or a quadrangular shape having an upper portion oval. delete delete delete The method of claim 7,
The rolling-
Further comprising a reinforcing member provided on the pontoon to reinforce the transverse vibration reducing member. The method of claim 11,
Wherein the reinforcing member is foldably provided on the pontoon. delete delete
KR1020120012451A 2012-02-07 2012-02-07 Semi-submersible marine structure KR101681710B1 (en)

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KR1020120012451A KR101681710B1 (en) 2012-02-07 2012-02-07 Semi-submersible marine structure

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KR101681710B1 true KR101681710B1 (en) 2016-12-13

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Publication number Priority date Publication date Assignee Title
KR101601025B1 (en) 2014-12-01 2016-03-21 한국해양과학기술원 Motion attenuating platform for offshore structures and marine semi-submersible structures equipped with it

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62292587A (en) * 1986-06-10 1987-12-19 Sumitomo Heavy Ind Ltd Underwater floating body for semi-submerged marine structure
KR20020037926A (en) * 2000-11-16 2002-05-23 김형벽ㅂ High-efficiency Bilge Keels
KR20050034601A (en) * 2001-10-09 2005-04-14 씨호스 이퀴프먼트 코포레이션 Method and apparatus for achieving hydrostatic stability of a floating structure while ballasting
KR101039371B1 (en) 2010-11-25 2011-06-08 주식회사 지주 Pontoon

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