# US 12,000,246 B2 · Method for evacuating hydrocarbon from a subsea process module

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- Number: US 12,000,246 B2
- Document ID: US12000246B2
- Status: Granted
- Kind: B2
- Application number: 17/924,328
- Filed: 2021-05-07
- Published: 2023-06-08
- Granted: 2024-06-04
- Earliest claimed: 2020-05-11
- Applicants: FMC Kongsberg Subsea AS
- Inventors: Leif Arne Tønnessen; Lachlan McKenzie
- Web page: https://patentgrep.com/patent/US12000246B2

## CPC

- E21B 43/01: specially adapted for obtaining from underwater installations
- E21B 41/0007: {for underwater installations (E21B41/005, E21B41/04, E21B41/06, E21B41/08, E21B41/10 take precedence)}
- E21B 43/0107: {Connecting of flow lines to offshore structures (E21B43/013 takes precedence)}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

Method for evacuating hydrocarbon from a subsea process module (210), the subsea process module having an upper fluid connection point (222) and a lower fluid connection point (232), the method comprising: connecting (110) a receiving container line (220) to the upper fluid connection point (222) of the subsea process module (210); connecting (120) a liquid adding line (230) to the lower fluid connection point (232) of the subsea process module (210); displacing (130) hydrocarbon by a liquid displacement medium added through the liquid adding line (230); removing (140) the liquid adding line from the lower fluid connection point (232); connecting (150) a gas adding line (260) to either the upper fluid connection point (222) or a lower fluid connection point (232); connecting (160) a receiving container line (220) to the lower fluid connection point (232) and or another lower fluid connection point; diluting (170) the remaining hydrocarbon by a gas medium added through the gas adding line (260).

## Claims

### Claim 1

A method for evacuating hydrocarbons from a number of pockets within a subsea process module, the subsea process module having a number of upper fluid connection points and a number of lower fluid connection points, the method comprising:
connecting a receiving container line to one of said upper fluid connection points of the subsea process module;
connecting a liquid adding line to one of said lower fluid connection points of the subsea process module;
displacing hydrocarbon from the subsea process module through the receiving container line by adding a liquid displacement medium through the liquid adding line;
removing the liquid adding line from said one of said lower fluid connection points;
connecting a gas adding line to one of said upper fluid connection points or one of said lower fluid connection points;
connecting the receiving container line to one of said lower fluid connection points; and
adding a gas medium through the gas adding line to thereby dilute a gas-phase portion of the hydrocarbon that has been trapped in at least one of said pockets within the subsea process module.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the subsea process module is a subsea compressor module.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the liquid displacement medium is a high-density liquid medium.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the high-density liquid medium includes monoethylene glycol (MEG).

### Claim 5 (depends on 1)

The method according to claim 1, wherein the gas medium is nitrogen.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the step of displacing the hydrocarbon includes displacing a liquid-phase portion of the hydrocarbon.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the displacing step includes transferring fluid from the subsea process module to an external container connected to the receiving container line.

### Claim 8 (depends on 7)

The method according to claim 7, wherein the external container is a flow conditioning unit.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the displacing step is continued until a first predetermined condition is met.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the first predetermined condition is met when a measured amount of liquid displacement medium exceeds a predetermined limit.

### Claim 11 (depends on 9)

The method according to claim 9, wherein the displacing step includes transferring fluid from the subsea process module to an external container connected to the receiving container line, and wherein the first predefined condition is met when a liquid level in the external container exceeds a predetermined level limit.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the diluting step is continued until a second predetermined condition is met.

### Claim 13 (depends on 1)

The method according to claim 1, further comprising, subsequent to the diluting step, retrieving the subsea process module from a subsea location.