System adapted for metering flow of a fluid, the system comprising: a vibratable flowtube for receiving a multiphase fluid flow including water and a petroleum fluid; a driver (46a, 46b) configured to vibrate the flowtube; a pair of sensors (48a, 48b) positioned to detect movement of the flowtube at different locations on the flowtube and output sensor signals indicative of the detected movement; a pressure sensor positioned to measure a pressure of the multiphase fluid; a temperature sensor positioned to measure a temperature of the fluid; and one or more processors configured to receive the sensor signals, determine a phase difference between the sensor signals, and use the determined phase difference to determine a fluid flow rate through the flowtube, wherein said one or more processors are further configured to: receive a signal from the pressure sensor indicative of the pressure of the multiphase fluid in the flowtube; receive a signal from the temperature sensor indicative of the temperature of the multiphase fluid in the flowtube; and receive a signal from a meter indicative of relative amounts of multiple different liquids in the multiphase fluid; characterized in that said one or more processors are further configured to: determine an amount of dissolved gas in the multiphase fluid using the pressure, the temperature, and the relative amounts the multiple liquids in the multiphase fluid, according to a gas solubility model, wherein the gas solubility model includes an adjustable tuning factor that allows the gas solubility model to be tuned to account for the fact that actual petroleum fluids do not always behave in the same way, and determine the fluid flow rate by using a mapping between a plurality of inputs and at least one output related to the fluid flow rate, wherein the inputs comprise a raw mass fluid flow rate, pressure of the fluid, temperature of the fluid, and the relative amounts of the multiple liquids in the multiphase fluid. a vibratable flowtube for receiving a multiphase fluid flow including water and a petroleum fluid; a driver (46a, 46b) configured to vibrate the flowtube; a pair of sensors (48a, 48b) positioned to detect movement of the flowtube at different locations on the flowtube and output sensor signals indicative of the detected movement; a pressure sensor positioned to measure a pressure of the multiphase fluid; a temperature sensor positioned to measure a temperature of the fluid; and one or more processors configured to receive the sensor signals, determine a phase difference between the sensor signals, and use the determined phase difference to determine a fluid flow rate through the flowtube, wherein said one or more processors are further configured to: receive a signal from the pressure sensor indicative of the pressure of the multiphase fluid in the flowtube; receive a signal from the temperature sensor indicative of the temperature of the multiphase fluid in the flowtube; and receive a signal from a meter indicative of relative amounts of multiple different liquids in the multiphase fluid; receive a signal from the pressure sensor indicative of the pressure of the multiphase fluid in the flowtube; receive a signal from the temperature sensor indicative of the temperature of the multiphase fluid in the flowtube; and receive a signal from a meter indicative of relative amounts of multiple different liquids in the multiphase fluid;