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Challenge: Ascertain cause of inaccurate water/liquid ratio (WLR) and gas/oil ratio (GOR) measurements acquired using Vx multiphase well testing technology.
Solution: Collaborate with OEM OneSubsea regarding log files from Vx technology and historical data from FRIEND remote surveillance and diagnostic system.
An operator was producing from fields offshore West Africa. The Vx multiphase well testing technology deployed in the operation began reporting high WLRs and GORs although the producing interval was known to contain no water. The operator therefore sought a solution for these unreliable measurements reported with Vx technology.
The operator turned to OneSubsea for a solution because, as the OEM, it knew the technology best. After consulting with the operator about the issue, OneSubsea requested the log files of the Vx technology and historical data saved in the FRIEND remote surveillance and diagnostic system. Critical flowmeter parameters from these datasets were closely examined. The operating point had shifted over time to the left side.
Based on these observations, OneSubsea concluded that a solid deposit may have formed on the Vx technology flowmeter window, specifically on the beam path where the flowmeter emitted gamma ray. Solid deposition can make the empty pipe reference inaccurate and potentially affect the calculation of the fractions based on the number of the counts received on the detector side, resulting in uncertainty in the flow rate reports.
OneSubsea issued an updated configuration file for the Vx technology flowmeter in question. The possible solid deposit on the Vx technology window was assumed to be a permanent physical part of the meter, and new empty pipe references on both low and high energy levels were used to update the configuration.
The operator installed the updated file prepared by OneSubsea. This update on the configuration file compensated for the plausible solid deposit formed on the Vx technology window and took the operating point back to the oil-gas line. As a result, the WLR reported using Vx technology changed from nearly 30% to 1.5%, which matched the operator’s expectation for the field. Based on the assumptions provided by the operator, the accuracy for calculating the WLR was improved by almost 28.5%.