This paper presents results from a flow test performed by TechnipFMC (TFMC) in December 2019 at the DNVGL Materials Laboratory in Oslo. A replica subsea multiphase meter (MPM) that includes a Venturi was used firstly to calibrate an Acoustic Sand Detector (ASD) for the X-mas Tree (XT) specific geometry, and secondly to monitor the impact of sand over the life of a typical high-rate subsea gas well.
The replica subsea MPM body was built to mimic the subsea installation on a 5-inch TFMC Subsea 2.0 XT. Several sensors were then mounted on the test rig – including ASDs and Wall Thickness Monitors (WTM) on the MPM block. Phase 1 testing was conducted over a range of air velocities with various sand particle sizes and with water injection to assess ASD sensitivity. In Phase 2, high air velocity and simultaneously high sand loading were applied to evaluate the response of erosion monitoring sensors and the mechanical robustness of the system.
It was shown that the sensitivity of the ASD mounted on the MPM block was satisfactory and that furthermore, standardized calibration curves can be generated, thereby allowing a more accurate measurement of the sand mass flow rate for the specific XT geometry. The capability of WTMs placed at the meter Venturi to monitor long-term erosion was also demonstrated.
To our knowledge, such a complete flow test with sand has never been performed on a full-scale subsea MPM geometry. The knowledge produced has allowed the verification of the accuracy of CFD erosion models, ASD calibration and the potential for development of an Erosion Monitoring System (EMS) using inputs from a range of sensors integrated into a single ROV-retrievable XT mounted metering system.