Arrangement and method for monitoring of annulus volume
Assignee4Subsea AS
InventorsTorbjørn AMUNDSEN, Carl Olav WICKMANN, Henrik TVEDT
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Abstract
The present description is related to integrity monitoring of an annulus volume in a pipe. More specifically, the present disclosure is related to an arrangement and a method for determination of annulus free volume of a pipe. The monitoring can as an example be performed by use of a logical unit which controls the annulus testing by use of diffusion or gas feed, and also give input to calculation of the pipe's remaining lifetime. Further, the arrangement can as an example save and present results, allow for user specified settings and set off alarms it critical values are detected.
Claims28
An arrangement for determination of annulus free volume (301, 401) in a pipe, the arrangement comprising:
- a reference volume (304, 404),
- at least one valve (302, 402) connected to the annulus volume (301, 401) and the reference volume (304, 404) for depressurization of the annulus volume (301, 401) to the reference volume (304, 404),
- at least one valve (305, 405) connected to the reference volume (304, 404) and at least one outlet (306, 406) for depressurization of the reference volume (304, 404), and
- at least one pressure instrument (316, 416, 303, 403) for pressure measurement of the annulus volume (301, 401), where the mentioned valves (302, 402, 305, 405) and the at least one pressure instrument (303, 403, 316, 416) is arranged to read off and control the pressurization and depressurization, and where pressure measurements in the reference volume (304, 404) and in the annulus volume (301, 401) prior to and after depressurization, together with the reference volume (304, 404) dimension/size are used for calculation of the annulus free volume.
Arrangement according to claim 1, where the calculation of the annulus free volume is performed by equations according to claim 17.
A method for determination of annulus free volume (301, 401) in a pipe, characterized by acts comprising:
- establishing a pressure difference between the annulus volume (301, 401) and the reference volume (304, 404),
- performing a number of depressurizations from the annulus volume (301, 401) to the reference volume (304, 404), where the number of depressurizations is one or more,
- measuring the annulus volume pressure prior to and after the number of depressurizations, and
- calculating the annulus free volume based on the measured pressure in the annulus volume (301, 401) prior to and after the number of depressurizations, pressure in the reference volume (304, 404) prior to and after each of the number of depressurizations and the reference volume dimension/size.
Dependencies are inferred from the claim text.