# US 2013/0153240 A1 · Offshore Well Drilling System With Nested Drilling Risers

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- Number: US 2013/0153240 A1
- Document ID: US20130153240A1
- Status: Published application
- Kind: A1
- Application number: 13/719,468
- Filed: 2012-12-19
- Published: 2013-06-20
- Earliest claimed: 2011-12-19
- Assignees: Cameron International Corporation
- Inventors: William Puccio; David Cain; Vijay A. Cheruvu; Shian Jiun Chou
- Web page: https://patentgrep.com/patent/US20130153240A1

## CPC

- E21B 19/006: {including heave compensators}
- E21B 7/12: Underwater drilling (using heave compensators E21B19/09)
- E21B 7/132: from underwater buoyant support
- E21B 17/01: Risers
- E21B 17/012: {with buoyancy elements (E21B17/015 takes precedence)}
- E21B 19/004: {supporting a riser from a drilling or production platform}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

An offshore well drilling system for drilling a subsea well, including a floating platform, an external riser extending from the subsea well, and an internal riser extending from the subsea well to the platform. The internal riser is nested within the external riser. The system also includes an external riser tension device to apply tension to the external riser. The system also includes an internal riser tension device, separate from the external riser tension device, to apply tension to the internal riser.

## Claims

### Claim 1

An offshore well drilling system for drilling a subsea well, including:
a floating platform;
an external riser extending from the subsea well;
an internal riser nested within the external riser and extending from the subsea well to the platform;
an external riser tension device to apply tension to the external riser; and
an internal riser tension device, separate from the external riser tension device, to apply tension to the internal riser.

### Claim 2 (depends on 1)

The system of claim 1, further including well pressure control equipment located on the platform and connected with the internal riser, the well pressure control equipment being the only well pressure control equipment for the well.

### Claim 3 (depends on 1)

The system of claim 1, wherein the internal riser is free to move within the external riser.

### Claim 4 (depends on 1)

The system of claim 1, further including the internal riser tension device to tension the internal riser independently of the external riser.

### Claim 5 (depends on 1)

The system of claim 1, further including the external riser tension device to tension the external riser independently of the internal riser.

### Claim 6 (depends on 1)

The system of claim 1, further including the internal riser connectable with the external riser such that the external riser is capable of applying tension to the internal riser in tension.

### Claim 7 (depends on 1)

The system of claim 1, further including the external riser connectable with the internal riser such that the internal riser is capable of applying tension to the external riser.

### Claim 8 (depends on 1)

The system of claim 1, further including the internal riser tension device to place the internal riser in tension dynamically.

### Claim 9 (depends on 1)

The system of claim 1, further including the external riser tension device including at least one of an air can, balloon, and foam.

### Claim 10 (depends on 1)

The system of claim 1, wherein the internal riser extends from an upper end of the external riser when installed.

### Claim 11 (depends on 1)

The system of claim 1, wherein only a portion of the internal riser is nested within the external riser.

### Claim 12

An offshore well drilling system for drilling a subsea well, including:
a floating platform;
a subsea wellhead;
an external riser extending from the subsea wellhead;
an internal riser nested within the external riser and extending from the subsea wellhead to the platform;
an external riser tension device to place the external riser in tension;
an internal riser tension device, separate from the external riser tension device, to dynamically place the internal riser in tension; and
well pressure control equipment located on the platform and connected with the internal riser, the well pressure control equipment being the only well pressure control equipment for the well.

### Claim 13 (depends on 12)

The system of claim 12, wherein the internal riser is free to move within the external riser.

### Claim 14 (depends on 12)

The system of claim 12, further including the internal riser tension device to tension the internal riser independently of the external riser.

### Claim 15 (depends on 12)

The system of claim 12, further including the external riser tension device to tension the external riser independently of the internal riser.

### Claim 16 (depends on 12)

The system of claim 12, further including the internal riser connectable with the external riser such that the external riser is capable of applying tension to the internal riser in tension.

### Claim 17 (depends on 12)

The system of claim 12, further including the external riser connectable with the internal riser such that the internal riser is capable of applying tension to the external riser.

### Claim 18 (depends on 12)

The system of claim 12, further including the external riser tension device including at least one of an air can, balloon, and foam.

### Claim 19 (depends on 12)

The system of claim 12, wherein the internal riser extends from an upper end of the external riser when installed.

### Claim 20 (depends on 12)

The system of claim 12, wherein only a portion of the internal riser is nested within the external riser.