Method for sampling and analysis of production from a subsea well for measuring salinity of produced water and also volumetric ratio between liquid fractions

摘要

The Invention concerns a permanent subsea sampling and analysis system (1), which typically is integrated into a replaceable equipment module for a choke valve (2) of a subsea production well. The analysis system (1) separates a sample into liquid fractions consisting of crude oil, condensate and produced water and then measures the salinity of the water as well as the volumetric ratio between the liquid fractions. With this equipment it will be possible to check, at regular intervals, the development in salinity of the produced water from a singular well without disturbing the production from the well. The information from the analysis system (1) may be used to update the calibration set-up of the multiphase flow meter of the well, or to reveal a possible water breakthrough resulting from water injection into a reservoir, or for other reservoir analyses. Due to the analysis equipment becoming permanently installed on the subsea well equipment, costs of taking samples via intervention operations from vessels are avoided, also avoiding temporary shut-down of production from other wells producing to a joint subsea manifold for the purpose of investigating which well may possibly have experienced water breakthrough.