Fluid Characterization in a subsea on-line multiphase fluid sampling and analysis sytem

The trend in subsea petroleum production systems in offshore field developments points towards integrated production and processing facilities at the seabed along with more extensive use of multiphase transportation technology.

The SOFA (Subsea On-line multiphase Fluid sampling and Analysis) system designed by Christian Michelsen Research in cooperation with the University of Bergen is an autonomous metering station for permanent installation subsea. The SOFA carries out fluid analysis subsea, and the current method of transfer of fluid samples to surface by a remote operated vehicle is avoided.
A laboratory prototype for capturing multiphase fluid samples in a dedicated measurement chamber/sample container has been built and tested. This is equipped with ultrasound sensors, a dual modality densitometer (DMD) gamma-ray system, pressure and temperature sensors, which together with conductivity, permittivity or similar measurements will be used as a multi-modality system for fluid characterisation.

This paper presents experimental results for fluid sampling and characterisation based on multimodality. The focus is on detection and monitoring of water salinity, water density and oil density. In addition, perspectives for operational use are discussed.