Evaluation of Commercially Available Virtual Flow Meters (VFMs)

摘要

This report documents a project to improve subsea flow measurements to allow the flowrates of individualrnwells to be known more accurately. Because production revenues are determined from flowrates,rnimproved flow measurement reduces the financial risk to stakeholders, including producers and the U.S.rngovernment. Improved measurement also helps to improve reservoir recovery. In this study, commerciallyrnavailable flow models were evaluated for their suitability as virtual flow meters (VFM).rnVirtual flow meters use input from sensors installed at various measurement points (nodes) in thernwellbore, on the seabed and in surface facilities. The evaluation of this approach to flowrate metering isrnparticularly meaningful in deepwater subsea applications to complement and backup physical measurementsrnrobustly and in a cost effective manner. The soft implementation of this modeling approachrnleverages already existing information from various measurement devices in the in the wellbore andrnsubsea infrastructure.rnThe study aimed at assessing the implementation and performance of commercially available VFMrnsoftware packages using real production data from a subsea well equipped with a subsea multiphasernflowmeter (MPFM). The study consisted of three evaluation rounds involving five commercial VFMrnproducts. The models were tuned incrementally using the subsea multiphase meter elemental computingrnparameters consisting of total mass flowrate, gas volume fraction (GVF), and water-liquid ratio (WLR).rnThe results from a series of ‘blind’ tests were compared to actual flowrates with the objective to establishrnthe sensitivity of the models’ results to the measurement devices, the parameters used in the tuning, andrnmeasurement devices and fluids properties inconsistencies.rnCompared to other evaluations, the study is based on existing production data from a live well in whichrnextensive data quality checks were necessary prior to sharing the data with VFM suppliers. Such effortrnled to consistent and conclusive results from at least three VFM packages that completed all three studyrnrounds. The findings from the study using this data set confirm the robustness of VFM techniques inrnestimating production flowrates with adequate tuning. It was also established that VFM can be a costrneffective and reliable backup measurement instrument to an ailing subsea multiphase meter where partialrnmeter measurement and VFM can restore functionality to the combined flow measurement system.