# US 2010/0166500 A1 · Freestanding hybrid riser system and method of installation

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- Number: US 2010/0166500 A1
- Document ID: US20100166500A1
- Status: Published application
- Kind: A1
- Application number: 12/648,510
- Filed: 2009-12-29
- Published: 2010-07-01
- Earliest claimed: 2008-12-29
- Assignees: Petroleo Brasileiro S.A. - Petrobras
- Inventors: Francisco Edward Roveri; Jose Mauricio Teixeira da Gama Lima
- Web page: https://patentgrep.com/patent/US20100166500A1

## CPC

- E21B 17/012: {with buoyancy elements (E21B17/015 takes precedence)}
- E21B 17/015: {Non-vertical risers, e.g. articulated or catenary-type}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

This invention relates to an improved freestanding hybrid riser system (FHRS) with new component configurations at the interfaces at the top (3) and bottom (5) ends of the vertical section of the riser (1) in comparison with configurations already installed by the industry. This proposed invention also describes a method for installation of the proposed FHRS which makes it possible to use vessels which are more available on the world market and therefore to bring about improved technical and operational gains.

## Claims

### Claim 1

Improved freestanding hybrid riser system, characterised in that it has new configurations for the top (3) and bottom (5) ends of the vertical section of the riser (1) and these new configurations are tubular structures in the form of spatial portals known as the Top Riser Assembly (TRA) (16) and Bottom Riser Assembly (BRA) (18).

### Claim 2 (depends on 1)

Improved freestanding hybrid riser system according to claim 1, characterised in that the TRA (16) provides a load path for the pull applied by the floating tank (2) at a point located at a horizontal distance h1 which is the distance between the principal axis of the tie bar (4) and the vertical section of the riser (1), while the vertical force exerted by the flexible jumper (12) is applied at a horizontal distance (h1+h2) which is the distance between the vertical section of the riser (1) and the end of the vertical connection module (17) connected to the TRA (16) and h1 and h2 depend upon design variables such as the water depth (WD) and the dimensions of the system components.

### Claim 3 (depends on 1)

Improved freestanding hybrid riser system according to claim 1, characterised in that a fitting connected to a vertical connection module (17) is located outside the limits of the horizontal projection of the floating tank (2), enabling the flexible jumper (12) to be connected after installation of the vertical section of the riser (1).

### Claim 4 (depends on 1)

Improved freestanding hybrid riser system according to claim 1, characterised in that the vertical reaction force at the interface between the riser (1) and the base (8) is transmitted to the Bottom Riser Assembly (BRA) (18) at a point located at a horizontal distance h3 which is the distance between the vertical axis of the base (8) and the vertical section of the riser (1), while the vertical force exerted by the rigid juniper (9) is applied at a horizontal distance h4 which is the distance between the vertical section of the riser (1) and the interface between the BRA (18) and the rigid jumper (9) and h3 and h4 depend upon design variables such as the water depth (WO) and the dimensions of the system components.

### Claim 5 (depends on 1)

Improved freestanding hybrid riser system according to claim 1, characterised in that the flexjoint (19) significantly attenuates the bending moment transmitted by the lower strengthening joint (7) to the structure of the BRA (18) and the rigid jumper (9), in that it acts as a filter for the bending forces produced.

### Claim 6

Method for installation of the improved freestanding hybrid riser system, characterised in that it uses a vessel equipped with dynamic positioning of the PLSV (22) type which can be used to install pipe using the Reel Method and another vessel of the crane and lay barge type—BGL1 (25) having a nominal capacity of 1000 tons to carry out the final installation activities.

### Claim 7 (depends on 7)

Method for installation of the improved freestanding hybrid riser system according to claim 7, characterised in that the lower strengthening joint (7) is connected to the BRA (18) onshore and the assembly is transported to the place where the proposed FHRS is installed on the deck of the PLSV vessel (22).

### Claim 8 (depends on 7)

Method for installation of the improved freestanding hybrid riser system according to claim 7, characterised in that the assembly of the lower strengthening joint (7) with the BRA (18) is lifted by the crane (24) of the PLSV vessel (22) and is transferred to the tower (23) where the first standard joint (21) is welded to the lower strengthening joint (7) and the standard joints (21) are subsequently lowered by the Reel Method.

### Claim 9 (depends on 7)

Method for installation of the improved freestanding hybrid riser system according to claim 7, characterised in that the assembly comprising the BRA (17), lower strengthening joint (7) and standard joints (21) is vertically supported by the bottom part of the tower (23) of the PLSV vessel (22) and the crane (24) on that vessel lifts the upper strengthening joint (6) from the deck and transfers it to the tower (23) where it is welded to the top end of the standard joints (21) and subsequently the assembly is lowered by a steel cable to a depth where a transfer can be made to a crane and lay barge—BGL1 (25) having a high load lifting capacity which concludes installation of the proposed FHRS.