Method of repairing a floating semi-submersible drilling platform

 

The invention relates to shipbuilding, and more specifically to a method of repair of floating structures, in particular the floating semi-submersible drilling platforms. Examination and repair of platforms produced in the course of its operation afloat without interrupting communication with the borehole. This in turn dried up group of compartments. Constantly support platform within the allowable settlement of strength, stability, and resistance to flooding and landing to ensure safety in the operation mode, and a violent storm. To access some of the compartments forming additional openings in the bulkheads between compartments. After the repair passages is eliminated. For repair of individual groups of compartments pre deballasting platform. It podplyvaet at the lowest possible operating draught of dminwithout interrupting the communication with the borehole. This is an opportunity to repair the platform afloat without docking and without interrupting communications with the borehole. 2 C.p. f-crystals, 11 ill.

The invention relates to the field of shipbuilding and repair of floating structures, in particular semi-submersible floating platforms.

Widely known is the cation (see Pat. Norway 148953, MKI663 With 1/00 from 31.03.1981 year). They effectively solve the problem of repair of the platform, however, require removal of the latter from operation and docking and docking is one of the most costly processes in shipbuilding due to the high cost of dock structures.

Also known some methods of repair of floating structures, in particular semi-submersible floating platforms afloat without drydocking.

One of such known methods of repair of floating structures, mainly semi-submersible floating platform containing operations of dismantling the damaged part of the hull and welding of newly manufactured parts removed damaged parts without the use of drydocking (see and.with. The USSR 1625764, MKI663 In 9/04 from 1988).

However, this known method is designed to repair only the individual metal platforms, in particular, inclined braces, which is above water, and may not be used in the repair of other critical elements, such as the lower pontoons under water.

There is also known a method of repairing a floating semi-submersible drilling platform having a stabilizing columns and the lower postprocess operation, and anchor the restraint system; includes examination of individual compartments by accessing them via the regular aisles and subsequent repair (see international application WO 99/57011 from 29.04.99 g, MKI663 IN 35/44).

For examination and repair of ballast compartments specified 15 known platform needs to be put in the dock and accordingly decommissioned because provided in the housings of the lower pontoons platform staff passes can be accessed only in compartments, which are located thrusters.

Drydocking, as mentioned above, is one of the most costly processes in ship repair. Before I go on drydocking it is necessary to conduct underwater technical works on disconnecting from the well or wells and maintenance of wells, removal of the platform from anchorage. When you return to the point of operation you want to perform the registration anchorage, re-entry wells and connecting to them. In addition, the repair of the platform ceases to give products. The cost of the above works, as well as losses from the termination of sales even more significant than the cost of drydocking.

Technical re the key into the dock without interrupting communications with the bore, without removing the platform from operational status and detach the anchor links.

This is achieved in a method of repairing a floating semi-submersible drilling platform having a stabilizing columns and the lower pontoons, divided into watertight compartments, as well as technological equipment associated with the well is in operation, and anchor the restraint system; includes examination of compartments by accessing them via the regular aisles and subsequent repair of the fact that the inspection and repair of platforms produced in the course of its operation afloat without interrupting communication with the borehole. This in turn drain the group's waterproof compartments platform, while constantly support platform within the allowable settlement of strength, stability, and resistance to flooding and landing to ensure safety in the operation mode, and a violent storm. For access in separate watertight compartments form additional passages, with said additional passages formed in the bulkhead common to the above-mentioned compartments and compartments available for examination, and then, after the repair, an additional pass of repair of individual groups waterproof compartments, pre-produce deballasting platform, in which she podplyvaet at the lowest possible operating draught without interrupting communication with the borehole. This is achieved by the fact that the additional passages formed in the form of openings watertight compartments.

For a more complete understanding of the problems below are excerpts from "CODE for construction and equipment of mobile drilling units (MODU CODE), International Maritime Organization, London, 1989 - "Code (collection of regulations) for the construction and equipment of floating drilling rigs", the international Maritime Organization, London, 1989

Chapter 3, section 3.4.3 - the Installation must have sufficient freeboard for and must be divided into compartments by watertight decks and bulkheads to provide sufficient buoyancy and stability..." Chapter 4 p. 4.9.1 - "Installation must be equipped with efficient ballast systems, pumps, able to take or to pump out the ballast in any ballast tank under normal conditions or when moving Pets... managed the ballasting gravity".

p. 4.9.2 - "Ballast system should provide the ability to transfer intact installation from the maximum normal operating the public means of keeping the installation at a given point, they must have a sufficient safety margin and should be designed to hold the mounting point for all design conditions."

Chapter 14, "Performance requirements" p. 14.1 - ". ..On Board facilities must be available and must be available for all whom they concern, instruction manual, which contains guidance on safe operation of the installation as normal and expected emergency conditions."

p. 14.1.2 - "the instruction manual shall include: 1. Description and characteristics of the installation.

. ..3. The limiting design parameters for each mode, including precipitation, ground clearance, the height of the waves...

5. The location is waterproof and splash-water compartments...

...6. The location, type, and number of permanent ballast, available at the facility.

...10. Information about stability... corresponding to the criteria of stability undamaged and damaged installation.

p. 14.1.3.4 instruction manual should also contain for installations with a stabilizing columns description, schemes and guidelines for the management of ballast system and alternative means for managing ballast system...

p. 14.1.3.7, the method of changing modes of operation.

p. 14.1.3.8 - who storm, etc. etc.

In Fig. 1 shows a General view of a floating semi-submersible drilling platform, repaired according to the invention; Fig. 2 - on the same platform, side view, without technological equipment, anchor systems and pipelines; Fig. 3 - section a-a of Fig.2 (top view on one of the lower pontoon, a second symmetrical layout); Fig.4 - section b-B of Fig.2 (one of the lower pontoon, a second symmetrical layout); Fig. 5 schematically shows the location of the watertight compartments (ballast tanks) in the lower pontoons and lower parts of the stabilizing columns; Fig.6-11 - implementation steps of the proposed method of repair.

Repaired by the present method semi-submersible platform 1 consists of the bottom two pontoons 2, eight stabilizing columns 3, the upper shell with the technological equipment 4 and braces 5. Platform 1 is connected with underwater wells (not shown) and installation of single buoy mooring loading (not shown) flexible pipelines 6 and is held at the point of operation of the anchor system 7. The lower pontoons 2 platform 1 split lengthwise 8 9 and transverse watertight bulkheads to separate watertight compartments. A large part of the waterproof deferred ballast tanks 11. The numbering of the ballast tanks 10 port and starboard (LB and TRB) of the lower pontoons 2 101(LB and TRB) to 1010(LB and TRB), and the numbering of the ballast tanks 11 columns 3 111(LB and TRB) to 114(LB and TRB). For filling and draining of tanks 10 and 11, the platform is equipped with a ballast system, including piping with valves and pumps (not shown).

In operation, the platform 1 is immersed for a certain draught d, the minimum operating draft denoted by dminlower the pontoons 2 and the lower part of the columns 3 are located under water. Ballast tanks 10 and 11 are filled with sea water. For access to ballast tanks 11 columns 3 from dry compartments 12 of the latter are the passages of the neck 13. For access to ballast tanks 10 pontoons 2 under stabilizing columns 3, regular passages - deck cap 14. Getting into the ballast tanks 10 the bottom of the pontoons 2, outside the area of the stabilizing columns 3 possible through regular neck 15; however, during operation, these necks are under water at a depth of 9-11 meters. Therefore, for access to ballast tanks 10, outside the area of the stabilizing columns 3, in the process Remo the examination. These additional passages formed in the openings 16.

Method of repairing a floating semi-submersible drilling platform according to the invention is carried out in the following sequence.

The platform 1 is in the operational state. Connection with the wells is not interrupted, the condition of the anchor system 7 normal working. Examine and record the filling of all ballast tanks 10 and 11.

stage 1 renovations for Example, found that ballast tanks 105, 111, 112and 114the left and right sides, as well as the ballast tank 1010TRB dry. Opening of the regular cap 13, leading from the dry compartments 12 columns 3 in ballast tanks 11 columns 3, fail and provide ventilation and temporary lighting (not shown), install if necessary, temporary ramps (not shown) and provide all necessary safety measures on maintenance of works (see, for example, paragraph 10.9 "Preparation of water tanks and ballast tanks to repair", "safety on vessels of the Navy", Reglamentaria MMF, M., 1975, S. 171-172), conduct inspection of these tanks and their repair if necessary (see Fig.6). Then from ballast tanks 112LB, 112TRB and 114TRB in stabilityselector and repair of ballast tanks 105LB, 105TRB, 1010TRB (see also Fig.6), while also fail and provide ventilation, temporary lighting, install if necessary, temporary ladders and provide all the security measures work.

stage 2 renovations
Through ballast system produce the draining of the tanks 106LB and 106TRB. This corresponds to the operating instructions of the platform. Thus, on the basis of a specific assessment of the security platform (stability, subdivision, strength, restraint system) permit or pdfsprite platform through deballasting to precipitation dminor take the ballast in the other compartments to ensure previous precipitation without pitch and roll.

From the dry tank 105LB and 105TRB in the transverse watertight bulkheads 9, shared with tanks 106LB and 106TRB, form additional passages - cut neck 16 for access to the tanks 106LB and 106TRB. After that, make examination and repair of tanks 106LB and 106TRB (see Fig. 7). After completion of the cap 16 zadravec (or disassemble, and cuts choke). The platform returns to its original position by Panych tanks 104LV and 104TRB, 107LB and 107TRB by deballasting. This procedure also corresponds to the operating instructions of the platform.

On the basis of a specific assessment of the security platform (stability, subdivision, strength, restraint systems) allow any pdfsprite platform, or accept the ballast in the other compartments to ensure continued precipitation without pitch and roll.

From the dry ballast tanks 112LB, 112TRB and tanks 113LB, 113TRB through the neck 14 are tanks in the bottom of the pontoons 2 and make examination and repair (Fig.8).

After completion of the work platform 1 return to its original position by ballasting.

stage 4 repairs
Through ballast system produce draining ballast tanks 102LB and 102TRB, as well as the tank 1010LB by deballasting. This procedure also corresponds to the operating instructions of the platform. From the dry ballast tanks 111LB, 111TRB and 114LB through the neck 14 fall into the tanks 102LB and 102TRB, as well as in tank 1010LB (see Fig.9).

stage 5 repairs
Through ballast system produce Ouse is. Getting into the tanks 109LB and 109TRB conduct of dry ballast tanks 114LB and 114TRB stabilizing columns 3 through the neck 14.

To get into the tanks 101LB and 101TRB need to leave after the fourth stage dry tanks 102LB and 102TRB, of which in the transverse bulkheads 9 cut additional cap 16 in the tank 101LB and 101TRB (see Fig.10).

After repair of tanks 101LB and 101TRB cap 16 is eliminated.

After the repair, perform parabolictrough platform 1.

stage 6 repairs
Through ballast system produce draining ballast tanks 103LB, 103TRB and 108LB, 108TRB. To contact them should be dry neighbouring tanks 105LB and 105TRB, and 109LB and 109TRB.

In the transverse watertight bulkheads 9 common to tanks 105LB, 105TRB and tanks 103LB, 103TRB, as well as tanks 109LB, 109TRB and 108LB, 108TRB cut additional cap 16 for access to the tanks 105LB, 105TRB and 108LB, 108TRB (see Fig.11). Produce inspection and repair of these tankwagon conditions, recommendations operating instructions and taking into account operating experience in conducting such operations may be adopted other variants of the sequence of operations, ballasting and deballasting.

Thus, using the invention it is possible to spend inspection and repair from within themselves ballast compartments and equipment that are in them, the most effective, simple and less time-consuming way, not taking the platform out of service without interrupting its connection with the well, afloat, without docking.

The estimated economic effect of the proposed method in the repair of one semi-submersible platform type "Aker H-3" will be about 5 million dollars.


Claims

1. Method of repairing a floating semi-submersible drilling platform having a stabilizing columns and the lower pontoons, divided into watertight compartments, as well as technological equipment associated with the well is in operation, and anchor the restraint system, which includes the examination of the mentioned compartments by accessing them via the regular aisles and subsequent repairs, characterized in that the inspection and repair of platforms which are groups waterproof compartments platform, constantly support platform within the allowable settlement of strength, stability, and resistance to flooding and landing to ensure safety in the operation mode, and a violent storm, and for access in separate watertight compartments form additional passages, with said additional passages formed in the bulkhead common to the aforementioned separate compartments and compartments available for examination and repair, and then after the repair, additional passages eliminated.

2. Method of repairing a floating semi-submersible drilling platform under item 1, characterized in that for repair of certain groups waterproof compartments pre-produce deballasting platform, in which she podplyvaet at the lowest possible operating draught without interrupting communication with the well.

3. Method of repairing a floating semi-submersible drilling platform under item 1, characterized in that the additional passages formed in the form of openings watertight compartments.

 

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4 cl, 22 dwg

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