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

Patent metadata

Field	Value
Publication number	US-2016290366-A1
Application number	US-201615185562-A
Country	US
Kind code	A1
Filing date	Jun 17, 2016
Priority date	Jun 11, 2012
Publication date	Oct 6, 2016
Grant date	—

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, whilst 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, whilst the compressor operates to compress the second fluid.

First claim

What is 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 from a separator, said compressor operating to compress the first fluid passed therethrough; b. mixing well fluid bypassed from upstream of the separator with said gas from the separator to produce a second fluid comprising gas and liquid, said gas and liquid being from at least one well; 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 . A method as claimed in claim 1 , which further includes, subsequent to step c, 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 . A 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/or 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 . A method as claimed in claim 1 , wherein 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 . A 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 . A method as claimed in claim 1 , wherein the first fluid has a liquid content of 0 to 5% by weight.

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

9 . A 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 or based on 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 . A 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 . A 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 the deposit, and wherein said performance of step c and/or step d is based on said identification.

12 . A 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/or 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 . A 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 said 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 . A method as claimed in claim 1 , wherein said well is a hydrocarbon well.

15 . A method as claimed in 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 . Apparatus for cleaning a compressor, the apparatus comprising:
a supply system for passing first and second fluids through the compressor for compressing the first or second fluids, said second fluid comprising gas and liquid from at least one well; and a control system arranged to supply the second fluid into the compressor via the supply system for a limited period of time to clean an inside surface of the compressor, wherein the first fluid comprises gas from a separator, and wherein the supply system comprises a branch arranged for well fluid to bypass the separator such that the well fluid is mixed or combined with the gas from the separator to produce the second fluid.

Assignees

• Statoil Petroleum As

Inventors

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

Classifications

• F04D31/00

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

• B08B5/02

  Cleaning by the force of jets, e.g. blowing-out cavities {(airguns or nozzles per se B05B1/005)} · CPC title

• B08B9/0328

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

• F04D29/701 Primary

  especially adapted for elastic fluid pumps · CPC title

• F04D29/705 Primary

  Adding liquids · CPC title