# US 4,398,846 A · Subsea riser manifold with structural spanning member for supporting production riser

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- Number: US 4,398,846 A
- Document ID: US4398846A
- Status: Granted
- Kind: A
- Application number: 06/246,526
- Filed: 1981-03-23
- Granted: 1983-08-16
- Earliest claimed: 1981-03-23
- Assignees: Mobil Oil Corporation
- Inventors: Fredric A. Agdern
- Web page: https://patentgrep.com/patent/US4398846A

## CPC

- E21B 43/0175: {Hydraulic schemes for production manifolds}
- E21B 41/08: Underwater guide bases, e.g. drilling templates; Levelling thereof
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A subsea riser mainfold system is disclosed for handling marine well fluids from multiple subsea wells and transmitting the well fluids through a marine production riser. The system includes a marine floor base template having a support structure and a manifold chamber supported thereon. Pile guides are connected to the template for fixing the template to the marine floor. The sealed manifold chamber hull is mounted on the template between the pile guides, enclosing manifold means for operatively connecting the subsea wells to the production riser. An improved structural spanning support member extends over the manifold chamber hull for receiving and supporting the marine production riser. This spanning member has an upper riser-receiving platform portion and structural spider arms connected between the platform production and the pile guides through the spanning member.

## Claims

### Claim 1

A subsea riser manifold system for handling marine well fluids from multiple subsea wells and transmitting the well fluids to a surface facility comprising:
a riser system including a buoy located below the surface of the water, a lower rigid section extending vertically downwardly from and maintained under tension by said buoy, and an upper flexible section between said buoy and the surface facility; said lower rigid section including a plurality of lower section flowlines supported by said buoy, and a strength member; said upper flexible section including a plurality of flexible flowlines, each connected to a respective one of said lower section flowlines;
a marine floor base template including a support structure and a plurality of pile guides connected to the template for fixing the template to the marine floor;
a sealed manifold chamber hull mounted on said support structure between said pile guides;
a structural spanning support member extending over said hull for receiving and supporting said strength member; said spanning member having an upper riser-receiving platform portion vertically spaced from said hull, and a plurality of spanning arms extending downwardly and outwardly from said platform portion, each of said spanning arms being connected to a respective one of said pile guides; and
said hull comprising manifold means therein for operatively connecting the subsea wells through said spanning member to said lower section flowlines, and means for maintaining a low pressure atmosphere;
whereby the buoyed riser load is transmitted directly to the pile guides through said spanning member.

### Claim 2 (depends on 1)

The system of claim 1 wherein said hull is a fluid-tight horizontal cylindrical pressure vessel.

### Claim 3 (depends on 2)

The system of claim 2 wherein a pair of said spanning arms extend downwardly and outwardly from said platform portion on each of opposite sides of said pressure vessel.

### Claim 4 (depends on 1)

The system of claim 1 wherein said spanning member includes a funnel structure for receiving said strength member.

### Claim 5 (depends on 1)

The system of claim 1 wherein said flexible flowlines extend in a catenary loop between said buoy and said surface facility.