JPS6331609B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a marine platform used for marine resource development.

There are three types of platforms used for drilling and producing oil and gas deposits on the seabed: jacket type, mooring type, jack up type, and gravity type, each of which has advantages but also disadvantages. be.

In other words, for the jacket type, the water depth is approximately
If the length exceeds 200 m, the weight of the structure will increase significantly, installation by towing will be technically difficult, the construction period will be long, and the construction cost will increase significantly. The mooring types that have a proven track record are the semi-sub type and the combination of a single-point mooring buoy and a ship, but both of them suffer from a drop in operating efficiency due to turbulence under severe sea and meteorological conditions. Many of these types employ submarine tunnels and subsea risers, making maintenance and inspection difficult. In addition, with the jack-up type, the weight of the structure increases significantly as the water depth increases, resulting in higher construction costs. Similarly, for the gravity type, the weight of the structure increases significantly as the water depth increases.
Furthermore, since the upper and lower structural parts of the platform are integrally constructed, it is difficult to arrange a construction site such as a deep-water harbor.

The present invention was made in view of the above-mentioned shortcomings of conventional marine platforms, and utilizes the superior functional parts of the jacket type, mooring type, and gravity type to create a new type of marine platform. This is what we intend to provide. That is, the present invention includes a caisson that sits on the seabed, a tower that stands on the caisson, and a plurality of mooring ropes that are fixed at one end to the top of the tower and are extended radially so that their tips can be removed from the caisson. It consists of a mooring device that is fixed to the seabed at a remote location with an anchor and has an intermediate sinker in the middle of each mooring line, and the joint between the caisson top surface and the tower bottom surface is concentric and bulges upward with the same radius of curvature. It is characterized by its spherical shape, which makes it a marine plastic that has a low structural weight even when the water depth increases, has excellent wave resistance and stability, and is easy to tow and install. We can expect the realization of Tutoform.

Hereinafter, an embodiment of the marine platform of the present invention will be described with reference to the drawings. As shown in FIG. has been done.

As shown in FIG. 2, the caisson part A has an opening 2 in the center of the caisson 1 for passing a conductor pipe 17 for well drilling and production wells, and a bulkhead 3 around the opening 2. Therefore, a large number of tanks 4, 4 for storing ballast water and produced crude oil...
At the same time, the lower surface of the caisson 1 is provided with a skirt 5 that protrudes downward and penetrates into the submarine ground E.
is provided.

As shown in Fig. 3, Tower B is formed of a truss structure with vertical legs 6, 6, etc. arranged at the four corners, and at its upper end is a deck on which well drilling equipment and crude oil production equipment are mounted. 7 is listed.
The lower end portion thereof is provided with a structure to be joined to a support portion installed on the upper surface of the caisson 1, as will be described later.

The support part C is a structural part that supports the tower B on the upper surface of the caisson 1, and the tower B and the caisson 1 are formed by curved surfaces forming concentric spherical parts that bulge upward with the same radius of curvature. Joined. That is, on the upper surface of the caisson 1, on the outside of the opening 2, narrow supports 8, 8, . , the respective supporting bodies 8 are connected to each other by a rod 9, and constitute a supporting part of the tower B on the caisson 1. On the other hand, at the lower end of the tower B, each vertical leg 6 and the connecting legs 10, 10, . An annular joined body 11 is formed in an annular shape so as to be in contact with the supporting body 8 and has a curved joint surface 12 corresponding to the supporting body 8 at a location corresponding to the supporting body 8 . Therefore, if an external force acts on tower B and causes it to sway, the support of caisson 1 and the joined body 1 of tower B
The curved joint surface with 1 is allowed to slide relatively.
The curved joint surface of the tower B is slightly wider than the support 8, and a stopper 1 is provided on the outside of the curved joint surface to prevent the tower B from rotating around the vertical axis.
3 is provided.

The mooring device D is for ensuring that the tower B is in an upright position, and has a plurality of mooring cables 14 fixed to the upper part of the tower B, one end of which is extended radially, and the middle part of the mooring cables 14 is connected to the submarine ground E by an intermediate singer 15. At the same time, the distal end portion is further fixed with an anchor 16. Under normal conditions, the intermediate sinker 15 acts as an anchor, and tower B is supported by the mooring rope between the intermediate sinker 15 and tower B. However, when the external load becomes large, such as in an abnormal environment, the intermediate sinker 15 lifts up. anchor 16
Tower B is supported by the entire mooring cable 14 from to tower B.

FIG. 4 shows another embodiment of the present invention,
The difference from the previous embodiment lies in the structure of the support portion C. That is, the curved joint surfaces of the support body 8 and the annular joint body 11 joined thereto are formed into curved surfaces based on the spherical surface 17 that bulges downward, contrary to the case of the previous embodiment. In this case as well, the supporting action of tower B is the same as in the previous embodiment.
Note that the other configurations are the same as those of the previous embodiment, so the same reference numerals are given to the equivalent parts, and the explanation will be omitted.

As explained above, the hybrid structure marine platform of the present invention includes a concrete gravity-type caisson that sits on the seabed, a flexible structure tower that stands on the caisson, and one end fixed to the top of the tower. The mooring device consists of a plurality of mooring lines, each of which is attached to an anchor on the seabed at the other end, and has intermediate sinkers in the middle. Since it is formed into a spherical shape with the same radius of curvature that swells out, it has many excellent effects as described below.

(1) Since the tower is a flexible structure, its natural vibration period can be increased to avoid synchronization with the wave period and earthquake period.

(2) Because the tower is supported by mooring lines, the weight increase with increasing water depth is much smaller than that of jacket, gravity, or jackup types. Moreover, since the mooring line has an intermediate sinker in the middle, the angle at which the mooring line is stretched up to the sinker is appropriate under normal conditions, but in abnormal environments where large external forces act, the angle of the mooring line can be adjusted against the swinging of the tower.
As the tension angle of the mooring cable becomes larger, the weight action of the intermediate sinker works, making it possible to appropriately control the swinging.

(3) Since the joint between the tower and the caisson is a spherical joint, no bending moment is generated due to horizontal external force applied to the tower. Furthermore, since the bonded spherical surface is a convex surface that bulges upward, foreign matter such as sand and dirt is difficult to enter.

(4) Since the caisson is a gravity type concrete caisson, it can have an oil storage function, and does not require large-scale civil engineering work when it is sunk, so the towing installation cost is low.

(5) The caissons and towers can be constructed separately in existing facilities, making it convenient for towing and shortening the overall construction period.

[Brief explanation of the drawing]

FIG. 1 is a partially longitudinal front view showing an embodiment of a marine platform having a hybrid structure according to the present invention;
FIG. 2 is a plan view showing the caisson and the support body, and FIG. 3 is a slope view showing the state of the joint between the caisson and the tower. A... Caisson part, B... Tower, C... Supporting part, D... Mooring device, E... Seabed ground, 1... Caisson, 2... Opening, 5... Skirt, 6...
Vertical leg, 7...Deck, 8...Support, 11...
zygote, 14... mooring rope, 15... intermediate sinker, 16... anchor.

Claims (1)

[Claims] 1. A concrete gravity-type caisson that sits on the seabed, a flexible structure tower erected on top of the caisson, and a plurality of mooring cables with one end fixed to the top of the tower, which are stretched radially and connected to their tips. is fixed to the seabed at a distance from the caisson by an anchor, and has an intermediate sinker in the middle of each mooring line, and the joint between the upper surface of the caisson and the lower surface of the tower is concentric and extends upward. A marine platform with a hybrid structure characterized by being formed into a spherical shape with the same radius of curvature.