Shell Offshore Inc.

Shell Oil Comapny

Dale M Gallaher

George E Sgouros

Mark Adrian Smith

A method is disclosed for redeploying an offshore platform structure from a first site to a second sight of different water depth in which the connection is released between a subsea jacket base and a plurality of piles which are anchored in the ocean floor at the first site. The offshore platform structure is vertically raised by pumping air into a tank member at the top of the subsea jacket base and the surface tower which is supported upon subsea jacket base is reworked while the jacket base is vertically raised. This operation is less difficult than attempting operations offshore on a horizontally disposed surface tower. The offshore platform structure is transported to the second site and the tank member is ballasted to vertically lower the offshore platform to the second site where it is installed.

Method for enhanced redeployability of hyjack platforms

An offshore platform structure is disclosed for temporarily using a jack-up rig for well operations in deepwater applications having a bottom founded jacket base which supports a surface tower which extends above the ocean surface and a subsea rig support interface which is adapted to support the jack-up rig for well operations. At least one selectively buoyant rig support buoyancy tank connected to the rig support interface whereby a portion of the temporary load on the jacket base in supporting the jack-up rig for drilling operations may be alleviated.

Hyjack platform with buoyant rig supplemental support

An offshore platform structure is disclosed for temporarily using a jack-up rig for well operations in deepwater applications in which a jacket base supports a surface tower and a subsea rig support interface adapted to accept the jack-up rig for well operations. The bottom founded jacket base is designed for dynamic response with the mass of the jack-up engaged and at least one ballastable rig support buoyancy tank connected to the rig support interface whereby the weight of the jack-up rig is substantially offset by buoyant forces supplied by the rig support buoyancy tank when the jack-up rig is deployed on the jacket base and the mass of the jack-up rig is substantially replaced in the offshore platform structure by ballast in the rig support buoyancy tank when the jack-up rig is removed.

Hyjack platform with compensated dynamic response

An offshore platform structure is disclosed for facilitating use of a jack-up rig for well operations in deepwater applications while reducing the jacket size and increasing the flexibility of field development. The structure has a bottom founded jacket base and a surface tower supported by the jacket base and extending above the ocean surface. A platform deck is supported by the surface tower and a subsea rig support interface is presented at the top of the jacket base which is adapted to receive the jack-up rig for well operations. Another aspect of the present invention is an offshore platform system which includes a jack-up rig having a plurality of legs extending from a combination hull/deck structure and engaging the rig support interface. Well operations equipment provided by the jack-up rig which includes a cantilever deck extending from the combination hull and deck structure to present a derrick in substantial vertical alignment with the surface tower.

Offshore platform structure and system

The present invention is a reusable jacket base for an offshore platform having a plurality of jacket legs with an interconnecting framework. Pile sleeves are connected to the jacket legs which have a vertically extended, open-ended cylindrical member having a second stage sleeve which is connected to the jacket leg and a first stage sleeve projecting coaxially from the second stage sleeve. First and second stage locking profiles are presented inside the first and second stage sleeves, respectively. The first stage sleeve is thus accessible for cutting operations, severing both the first stage sleeve with the first pile-to-pile sleeve connection inside and the connected pile section within. This allows retrieval of the platform jacket, but preserves a second stage pile sleeve for re-deployment. Another aspect of the present invention is an improved pile sleeve adapted to facilitate reuse.

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Metairie, LA, United States of America

Dale M Gallaher