Offshore structure and method of sinking same
First Claim
1. A method for sinking a structure having a first end portion and a second end portion to the sea bed comprising the steps of:
- a. ballasting said first end portion of the structure to sink said first end portion to the sea bed while said second end portion is closed to ballast;
b. ballasting said second end portion of the structure, after said first end portion is sunk, to sink said second end portion to the sea bed;
c. attaching at least one removable buoyancy member to the structure during at least one of steps a and b to maintain stability of the structure;
d. attaching at least two piles at the end corresponding to said first end portion of the structure;
e. spacing the piles over the length of said end; and
f. fixedly positioning the piles vertically so that bottom portions thereof are lower than a skirt on the structure to absorb the force of impact of said first end portion with the sea bed and to maintain the skirt out of contact with the sea bed until both ends of the structure have been sunk to the sea bed.
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Accused Products
Abstract
An offshore structure and a method of sinking it to the sea bed. In accordance with one aspect of this invention, the structure is sunk asymmetrically by first sinking a first end portion thereof and then sinking the other end portion. The first end portion is sunk by ballasting it while the other end portion is closed to ballast. The structure is provided with sufficient water plane area while sinking each end portion to maintain stability during the sinking process. In accordance with another aspect of this invention, at least two spaced-apart piles are provided at the end corresponding to the first end portion to absorb the force of impact with the sea bed and to maintain a skirt on the structure out of contact with the sea bed until both ends of the structure have been sunk to the sea bed.
13 Citations
18 Claims
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1. A method for sinking a structure having a first end portion and a second end portion to the sea bed comprising the steps of:
- a. ballasting said first end portion of the structure to sink said first end portion to the sea bed while said second end portion is closed to ballast;
b. ballasting said second end portion of the structure, after said first end portion is sunk, to sink said second end portion to the sea bed;
c. attaching at least one removable buoyancy member to the structure during at least one of steps a and b to maintain stability of the structure;
d. attaching at least two piles at the end corresponding to said first end portion of the structure;
e. spacing the piles over the length of said end; and
f. fixedly positioning the piles vertically so that bottom portions thereof are lower than a skirt on the structure to absorb the force of impact of said first end portion with the sea bed and to maintain the skirt out of contact with the sea bed until both ends of the structure have been sunk to the sea bed. - View Dependent Claims (2, 3, 6, 7, 8)
- a. ballasting said first end portion of the structure to sink said first end portion to the sea bed while said second end portion is closed to ballast;
- 4. A method for sinking a structure having a first end portion which terminates at a first end and a second end portion which terminates at a second end to the sea bed comprising attaching at least two piles to the structure at the first end of the structure, spacing the piles over the length of the first end, fixedly positioning the piles vertically so that bottom portions thereof are lower than a skirt on the structure, ballasting the first end portion of the structure while the second end portion is closed to ballast to sink the first end thereof to the sea bed while allowing the piles to absorb the force of impact of the first end with the sea bed and to maintain the skirt out of contact with the sea bed until both the first and second ends of the structure have been sunk to the sea bed, ballasting the structure to sink the second end thereof to the sea bed after the first end has been sunk to the sea bed, and releasing the piles so that they are free to move vertically relative to the skirt.
- 9. In an offshore structure having a skirt for penetrating the sea bed upon sinking thereof to the sea bed, a first end portion which terminates at a first end, a second end portion which terminates at a second end, at least two piles attached to the structure at said first end of the structure and spaced-apart over the length of said first end, means for fixedly positioning said piles so that they extend downwardly beyond said skirt to absorb the force of impact of said first end with the sea bed and to maintain the skirt out of contact with the sea bed until both said first and second ends of the structure have been sunk to the sea bed, means for releasing said piles so that they are free to move vertically relative to the skirt, and means for sinking said first end portion without sinking said second end portion.
Specification