# US 8,146,667 B2 · Dual gradient pipeline evacuation method

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- Number: US 8,146,667 B2
- Document ID: US8146667B2
- Status: Granted
- Kind: B2
- Application number: 12/804,258
- Filed: 2010-07-19
- Published: 2012-01-19
- Granted: 2012-04-03
- Earliest claimed: 2010-07-19
- Inventors: Marc Moszkowski; Benton Frederick Baugh
- Web page: https://patentgrep.com/patent/US8146667B2

## CPC

- E21B 43/36: Underwater separating arrangements (E21B43/38 takes precedence)
- E21B 41/0007: {for underwater installations (E21B41/005, E21B41/04, E21B41/06, E21B41/08, E21B41/10 take precedence)}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

The method of removing a first liquid from a subsea pipeline which has a central portion lower than each of the ends of the subsea pipeline by pumping a second lower density fluid into the pipeline and the either removing the second lower density fluid by either displacing it with gas or evaporating the second lower density fluid to a gas.

## Claims

### Claim 1

The method of removing a first liquid from a subsea gas pipeline which has an intermediate portion which is lower than the ends of said subsea pipeline, comprising:
displacing said first liquid from said subsea pipeline by pumping a second liquid into said pipeline, and
allowing at least a portion of said second liquid to evaporate to a gas.

### Claim 2 (depends on 1)

The method of claim 1 further comprising said first liquid is water.

### Claim 3 (depends on 1)

The method of claim 1 further comprising said second liquid is propane.

### Claim 4 (depends on 1)

The method of claim 1 further comprising said second liquid is butane.

### Claim 5 (depends on 1)

The method of claim 1 further comprising said second liquid is a propane/butane mixture.

### Claim 6 (depends on 1)

The method of claim 1, further comprising separating said first liquid from said second liquid during said pumping operations with a pig which seals in the bore of said subsea gas pipeline.