Subsea compressor cleaning method wherein the cleaning liquid is retrieved from the multiphase process fluid

Patent metadata

Field	Value
Publication number	US-9518588-B2
Application number	US-201214407379-A
Country	US
Kind code	B2
Filing date	Jun 11, 2012
Priority date	Jun 11, 2012
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

There are described methods and apparatus for operating and/or cleaning a compressor. In an embodiment, a first fluid comprising gas may be passed through the compressor, while the compressor operates to compress the first fluid. A second fluid may be passed through the compressor, the second fluid comprising gas and liquid from at least one well. The second fluid may be passed through the compressor for a limited time period to clean a surface inside the compressor, while the compressor operates to compress the second fluid.

First claim

The invention claimed is:

1. A method of operating and cleaning a compressor, the method comprising:
a. passing a first fluid through the compressor, said first fluid comprising gas, and said compressor operating to compress the first fluid passed therethrough;
b. modifying the first fluid to produce a second fluid comprising gas and liquid, said gas and liquid being from at least one well, wherein said modification comprises cooling said gas of the first fluid upstream of the compressor to condensate liquid, the liquid contained in the second fluid including said condensate liquid, or wherein said modification comprises changing the level of compression of the fluid by the compressor; and
c. passing the second fluid through the compressor, wherein said second fluid is passed through the compressor for a limited time period to clean a surface inside the compressor, said compressor operating to compress the second fluid passed therethrough.

2. The method as claimed in claim 1 , which further includes, subsequent to step b, the following step:
d. when said limited time period is over, passing a third fluid through the compressor wherein said third fluid contains either less liquid than said second fluid or no liquid.

3. The method as claimed in claim 1 which further includes:
determining the presence or potential presence of a deposit of material on said surface of the compressor; and
performing at least one of said step c and step d upon said determination, wherein said step d comprises: when said limited time period is over, passing a third fluid through the compressor, wherein said third fluid contains either less liquid than said second fluid or no liquid.

4. The method as claimed in claim 1 , wherein said step c is performed to least partly remove a deposit of material on said surface of the compressor, in order to clean said surface of the compressor.

5. The method as claimed in claim 1 , wherein the first fluid has a composition which, upon passage of the first fluid through the compressor, causes formation of a deposit on said surface inside the compressor.

6. The method as claimed in claim 1 , wherein the first fluid has a liquid content of 0 to 5% by weight.

7. The method as claimed in claim 1 , wherein the liquid contained in the second fluid is present in a greater amount than any liquid contained in the first fluid.

8. The method as claimed in claim 1 , wherein the amount of liquid contained in the second fluid is sufficiently great that complete vaporization of the liquid does not occur by passage of the second fluid through the compressor.

9. The method as claimed in claim 1 , which further includes:
identifying a changed performance of the compressor, said changed performance suggestive of a need for cleaning; and
performing at least one of said step c and/or step d after said identification, wherein said step d comprises: when said limited time period is over, passing a third fluid through the compressor, wherein said third fluid contains either less liquid than said second fluid or no liquid.

10. The method as claimed in claim 1 , which further includes:
measuring a property of the first fluid; and
performing step c and/or step d after said measurement or based upon said measured property, wherein said step d comprises: when said limited time period is over, passing a third fluid through the compressor, wherein said third fluid contains either less liquid than said second fluid or no liquid.

11. The method as claimed in claim 10 , which further includes using the measured property of the first fluid to identify a presence or possible presence of a deposit, and wherein said performance of step c and/or step d is based on said identification.

12. The method as claimed in claim 1 , which further includes:
measuring a property of a compressed fluid produced by compression of the first fluid upon passage through the compressor;
using the property of the compressed fluid to determine a need for cleaning; and
performing at least one of said step c and step d based on the determined need for cleaning, wherein said step d comprises: when said limited time period is over, passing a third fluid through the compressor, wherein said third fluid contains either less liquid than said second fluid or no liquid.

13. The method as claimed in claim 1 , which further includes:
measuring a property of a fluid to be compressed by the compressor or a fluid produced by compression by the compressor, or measuring a performance of the compressor;
comparing the measured property of said fluid or performance of the compressor with a reference value;
determining a need for cleaning based on said comparison; and
performing at least one of step c and/or step d upon determination the need for cleaning, wherein said step d comprises: when said limited time period is over, passing a third fluid through the compressor, wherein said third fluid contains either less liquid than said second fluid or no liquid.

14. The method as claimed in claim 1 , wherein said at least one well is a hydrocarbon well.

15. The method as claimed in any claim 1 , wherein the gas contained in the second gas comprises hydrocarbon gas, and the liquid contained in the second gas comprises at least one of hydrocarbon liquid, gas condensate and water.

16. A method of cleaning a compressor, the method comprising:
passing a fluid through the compressor, said fluid containing gas and liquid;
compressing the fluid to a first level of compression using the compressor; and
subsequently reducing the level of compression of the fluid by the compressor to a second level of compression, being lower than said first level of compression, wherein said second level of compression is chosen such that the fluid passed through the compressor cleans a surface inside the compressor.

17. The method as claimed in claim 16 , wherein said cleaning of the surface comprises removing a deposit from said surface of the compressor.

18. The method as claimed in claim 16 which includes a subsequent step of increasing the level of compression of fluid by the compressor to a third level of compression, being higher than said second level of compression.

19. The method as claimed in claim 18 , wherein said third level of compression is higher than said first level of compression.

20. The method as claimed in claim 18 , wherein at said first or third levels of compression, the fluid contains no liquid or insufficient liquid for cleaning said surface of the compressor.

Assignees

• Brenne Lars
• Bjørge Tor
• Underbakke Harald
• Kibsgaard Svend Tarald
• Statoil Petroleum As

Inventors

• Brenne Lars
• Bjørge Tor
• Underbakke Harald
• Kibsgaard Svend Tarald

Classifications

• F04D29/705

  Adding liquids · CPC title

• F04D29/701 Primary

  especially adapted for elastic fluid pumps · CPC title

• B08B9/0328

  by purging the pipe with a gas or a mixture of gas and liquid · CPC title

• F04D31/00

  Pumping liquids and elastic fluids at the same time · CPC title

• F04D25/0686 Primary

  specially adapted for submerged use · CPC title