Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B17/02—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/02—Surface sealing or packing
  • E21B33/03—Well heads; Setting-up thereof
  • E21B33/035—Well heads; Setting-up thereof specially adapted for underwater installations
  • E21B33/037—Protective housings therefor
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B17/02—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
  • E02B17/021—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto with relative movement between supporting construction and platform
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/01—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells specially adapted for obtaining from underwater installations
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B7/00—Special methods or apparatus for drilling
  • E21B7/12—Underwater drilling
  • E21B7/136—Underwater drilling from non-buoyant support
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0039—Methods for placing the offshore structure
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0056—Platforms with supporting legs
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0056—Platforms with supporting legs
  • E02B2017/0065—Monopile structures
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0056—Platforms with supporting legs
  • E02B2017/0069—Gravity structures

Definitions

• the present invention concerns a structure for the production of oil and/or gas from oil/gas fields located in geological formations under the sea bed.
• the present invention concerns a structure which can, in particular, be used for the production of oil and/or gas at moderate depths of the sea, i.e. depths of up to 200 metres.
• production means all phases of the work and equipment which are associated with the extraction of oil and/or gas, including drilling and testing, as well as the installation and operation of equipment, etc. for the extraction of oil and/or gas from the formation under the sea bed.
• the floating structures have the major advantages that they can be moved (removed) when production in the field in which they are located ceases, and that they can be used at greater depths of the sea. However, greater risks and technical problems are associated with the use of floating structures.
• the fixed structures are, however, solid and safe and have long lives, although they are generally expensive to build and use.
• the present invention represents an intermediate stage between a floating and a fixed structure. Intermediate because it is easy and inexpensive to build and use and it can easily be moved, but it rests on the sea bed.
• the present invention is characterised by a body which is designed to be lowered and placed on the sea bed and which extends from the sea bed above the surface of the sea.
• the lower part of the structure contains a space designed to hold equipment for the production of oil and/or gas and the upper part, as a minimum, contains a passage or column/shaft for the installation of hoists, pipes, cable paths, etc. and for communication with the surface.
• Fig. 1 shows a perspective view of a structure in accordance with the present invention.
• Fig. 2 shows an outline of a preferred embodiment of the structure in accordance with the present invention.
• Figs. 3 and 4 show cross-sections of the structure along the lines A-A and B-B in Fig.
• Fig. 5 shows a sequence of pictures of the structure shown in perspective. a) shows the structure under construction, b) shows how an annular equipment and operation part is positioned on the base part of the structure, c) shows the structure being towed out and d) shows the structure in an operative situation.
• Fig. 6 shows an alternative embodiment of a structure according to the invention.
• Fig. 7 shows, in enlarged scale, a cross section along lines C-C of the structure shown in Fig. 6.
• Fig. 8 shows the structure in Figs. 6 and 7 under installation.
• Figure 1 shows a structure 1 for the production of oil and/or gas in accordance with the present invention.
• the structure is designed to be placed on the sea bed and extends from the sea bed up to a level above the surface of the sea.
• the lower part 2 of the structure comprises a preferably circular, voluminous part with an internal space/internal spaces which is/are designed to hold the necessary equipment 6 for the production of oil and gas and which is/are indicated in part in the area 5 of the structure which has been cut open.
• the upper part 3 of the structure 1 which is connected to the lower part, comprises a preferably circular, column-like part which is designed to hold hoists, pipes and cables, etc. 7 which is shown in part in another section 8 of the structure which has been cut open.
• a helicopter deck 9 an area (not shown in detail) for taking on supplies, or pipes, valves, etc. and other equipment for discharging oil/gas (not shown either) in connection with the upper part of the structure.
• a helicopter deck 9 an area (not shown in detail) for taking on supplies, or pipes, valves, etc. and other equipment for discharging oil/gas (not shown either) in connection with the upper part of the structure.
• 1 is thus a structure in which the equipment for the production of oil and gas is placed in a cavity/cavities in the structure directly above the sea bed and can be operated and monitored (maintained) under "atmospheric" conditions, as the cavity/cavities is/are in direct communication with the atmosphere above the surface of the sea.
• the structure in accordance with the present invention can easily be moved to a new oil/gas field as, using a ballast system (not shown in detail), it can be lifted and then towed to the desired location.
• the present invention is much more reliable as the equipment is placed directly above the sea bed and there is no need for risers.
• Fig. 2 shows an outline and Figs. 3 and 4 show horizontal sections of a preferred embodiment of a structure in accordance with the present invention.
• the structure 1 consists of a column-shaped (pipe-shaped) part 13 which is connected to a lower foundation part 12 which is designed to rest on the sea bed.
• the column-shaped part 13 and the foundation part 12 are built expediently as an integrated section, for example of concrete in accordance with conventional principles (see Fig. 5 a) ).
• the structure consists of an annular part 11 with an internal space/internal spaces which is/are designed to hold the necessary production equipment (not shown in detail).
• the ring part 11 can also expediently be made of concrete and has an internal diameter which corresponds to the external diameter of the column 12. It is made as a separate section and is placed on the foundation 13 by threading it down over the column either after the column and foundation have been lowered over the oil/gas field in question or before the structure is towed out (see Fig. 5 b)).
• the column 12 and the annular part 13 are provided with corresponding, initially closed openings (not shown) and, after the ring part has been positioned, the openings are opened in order to achieve free passage from the ring part 11 to the surface via the column 12.
• Both the lower part of the column and the foundation and the ring parts are provided with ballast tanks (not shown) so that the buoyancy can be regulated while the respective parts are being lowered.
• Fig. 5 shows a sequence of pictures which illustrate the construction, assembly, towing out and operative positioning of a structure in accordance with the present invention.
• the structure is constructed in concrete at a suitable location in accordance with a conventional method with sliding falsework, see Fig. 5 a).
• the structure is assembled as shown in Fig. 5 b). This is done by first lowering the foundation and the column 12, 13, then placing the ring part 11 on a lighter or similar and towing it into position above the column 12, and finally lowering the ring part down over the column 12.
• the ring part While it is being towed to its destination, the ring part is kept in a position on the surface of the sea so as to create sufficient buoyancy and stability during the towing operation, as shown in Fig. 5 c). Finally, as shown in Fig. 5 d), when the structure has been towed to its destination over an oil/gas field, the necessary ballast is placed in the respective structural parts so that the ring part can be lowered to the foundation and the structure as a whole can be placed on the sea bed.
• ballast water is pumped out of the respective structural parts so that the structure again assumes the position shown in Fig. 5 c) for towing.
• Fig. 6 shows an alternative embodiment of the structure according to the invention. It comprises, as with the previously described structures, a column-like part 14 with an upper helicopter or service deck 15, and a lower base part 16.
• the base part is, however, in this embodiment provided with individual fixed 17 or releasable 18 (see also Fig. 8) ballasting or production cells.
• the fixed cells 17 are an integral part of the base, whereas the releasable cells are designed to be submerged and attached to the base 16 after having placed the structure 14,16 on the sea bed.
• the base 16 may be provided with an upwardly open cavity 19, whereby the cell 18 has a complementary shape to fit in the cavity 19. Openings (not shown) may further be provided between the cells 17,18 and column 14.
• Fig. 7 shows, in enlarged scale, a cross section of the base along line C-C in Fig. 6.
• the base in this example is provided with totally six cells, three fixed cells 17 and three releasable cells.
• the releasable cells 18 may be provided with production oil/gas equipment before being submerged and attached to the base 16.
• the fixed cells may be used for ballasting.
• the number of fixed and releasable cells may be of different number than what is shown in this figure.
• Fig. 8 shows a situation of the construction 14,16 according to Figs. 6 and 7 where a cell 18, under installation, is being submerged by means of pull line 20, which pulls the cell 18 towards the cavity 19 in which it is designed to be attached to the base 16.
• a towing barge 21 is holding the cell 18 in position under the installation process.
• the cells 17,18 may be of segment shape.
• the structure can be made of materials other than concrete, for example steel.
• the construction, towing and installation of the structure can take place in other ways. For example, if it is constructed in steel, it can be towed to its destination as a horizontal structure on which the ring part has been positioned before towing out.
• the structure can be fitted with two or more ring parts arranged above one another instead of just one ring part.

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• Engineering & Computer Science (AREA)
• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• Physics & Mathematics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Earth Drilling (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=19900461

Family Applications (1)

Country Status (4)

Family Cites Families (5)

• 1997
  • 1997-03-05 NO NO971001A patent/NO309436B1/no not_active IP Right Cessation
• 1998
  • 1998-02-25 AU AU64246/98A patent/AU6424698A/en not_active Abandoned
  • 1998-02-25 WO PCT/NO1998/000054 patent/WO1998039550A1/en not_active Ceased
  • 1998-02-25 EP EP98909878A patent/EP0961867A1/de not_active Withdrawn

Non-Patent Citations (1)

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