JPS62258014A - Method for setting off-shore platform - Google Patents

Abstract

PURPOSE:To shorten a setting period and reduce a setting cost, by a method wherein an upper structure is taken in tow to a setting place with the buoyancy of a lower hull to seat the structure on a lower jacket, and wherein the seating section of the lower hull is fixed. CONSTITUTION:An upper structure 3 is put in a floating state on the sea with the buoyancy of a lower hull 6 and is taken in tow to a setting site with a constructed lower jacket 1. After that, the structure 3 is positioned on the lower jacket 1, and the lower hull 6 is regulated in ballast. On the top receiver 2 of the lower jacket 1, the upper structure 3 is mounted, and the seating section of the lower hull 6 is fixed on the top receiver 2 of the lower jacket 1. As a result, it can be easily set on the lower jacket, and a setting period can be shortened, and a setting cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a method of installing an offshore platform for oil and gas drilling and production onto a subsea constructed lower jacket.

(Prior Art) An offshore platform for oil and gas drilling and production installed offshore is installed on a lower jacket constructed under the sea by the following installation method. That is, currently most of the platforms are 1000~
The construction will be divided into blocks of 2,000 tons or less, each block will be transported by lift barge etc. to the installation site, and each block will be lifted in sequence by a large derrick barge (a work boat equipped with a lift barge) at the installation site. They are installed sequentially on top of the lower jacket.

(Problems to be Solved by the Invention) In the conventional installation method, since a large derrick barge is used at the installation site, there are problems in that the installation period becomes long and the installation cost increases.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, the present invention provides a structure in which a lower jacket constructed under the sea is constructed such that its top part is submerged under the sea surface, and an offshore platform (integrated A superstructure with a lower hull with adjustable ballast attached to the bottom of a structure (built as a structure) via a column is assembled and manufactured on land, for example at a dock, and this superstructure is floated on the sea by the buoyancy of the lower hull. towing the towed structure to the installation location where the lower jacket is constructed; after positioning the towed structure on the lower jacket, ballasting the lower hull and seating the superstructure on the lower jacket; After the upper structure is seated, the lower hull seating portion is fixed and installed on the lower jacket.

(Operation) All the superstructures including the offshore platform are assembled on land, and the superstructures are floated on the sea and then towed and installed, so there is no need to use a large derrick barge at the installation site. Therefore, it is possible to shorten the installation period and reduce installation costs.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the figure, 1 is a lower jacket constructed under the sea as a side of a gas well, an oil well, etc. It is sunk to a predetermined depth H. The depth H at which this jacket top support sinks below the sea surface of the seat 2 is a water depth at which the lower hull 6 of the upper structure 3, which will be described later, does not touch the bottom while floating on the sea.

an upper structure 3 installed on the lower jacket 1;
is assembled and manufactured on land, for example, at a dock, and consists of an offshore platform 4 built as an integral structure, and a lower hull 6 with adjustable ballast attached to the bottom of the offshore platform 4 via a column 5. has been done. The lower hull 6 has an internally partitioned ballast tank (not shown), and trim, heel (inclination), and stuttering can be adjusted by adjusting the ballast of this ballast tank.

The offshore platform installation method of the present invention involves floating the upper structure 3 assembled on land on the sea by the buoyancy of the lower hull 6, and pulling it with a tugboat (not shown) to attach the lower jacket 1. be towed to the installation site where it is being constructed. Then, after positioning the structure 3 on the lower jacket 1 as shown by the imaginary line in Figure 1, the ballast adjustment of the lower hull 6 (adjustment to reduce the buoyancy and sink the upper structure 3 as a whole) is performed. Then, the top support of the lower jacket 1 seats the upper structure 3 (lower hull 6) on the seat 2 as shown in FIG.
After seating, attach the seating part of the lower hull 6 to the lower jacket 1.
The top support is fixedly installed on the seat 2.

Note that the ballast tank of the lower hull 6 is used as various storage tanks after installation.

(Effects of the Invention) Since the offshore platform installation method of the present invention is as described above, the upper structure with the lower hull attached to the lower part of the offshore platform via the column is floated on the sea and towed. Since it can be easily installed on top of the roof and does not require the use of large derrick barges at the installation site, it is possible to shorten the installation period and reduce installation costs.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an installation method of an offshore platform according to an embodiment of the present invention with the upper structure being towed at sea, and Fig. 2 is an illustration of the installation state in which the upper structure is seated and fixed on the lower jacket. It is. 1...Lower jacket, 2...Top support is seat, H...
・The depth of the top support is below the sea surface of the seat, 3...superstructure, 4...offshore platform, 5...column, 6...lower hull.

Claims (1)

[Claims] This superstructure consists of a lower jacket built in the sea, the top of which is submerged below the sea surface, and an upper structure assembled and manufactured on land, with a lower hull with adjustable ballast attached to the bottom of the offshore platform via a column. After the body is floated on the sea by the buoyancy of the lower hull and towed to the installation site and positioned on the lower jacket, the ballast of the lower hull is adjusted and the upper structure is seated on the lower jacket. A method for installing an offshore platform, characterized in that the lower hull seating part of the body is fixed to the lower jacket.