Glossary

Where applicable MEDENG has adopted multiphase flow measurement definitions from API RP 86-2005, API Recommended Practice for Measurement of Multiphase Flow.

commingle: To combine the hydrocarbon streams from two or more wells, units, leases, or production facilities into common vessels or pipelines.

emulsion: Colloidal mixture of two immiscible fluids, one being dispersed in the other in the form of fine droplets.

equations of state (EOS): Equations which relate the compositions, pressures, temperatures, and various other physical properties of gases and liquids to one another, and are used to predict the transformation of physical state when conditions change.

flow regime: The physical geometry exhibited by a multiphase flow in a conduit; the geometrical distribution in space and time of the individual phase components, i.e. oil, gas, water, any injected chemicals, etc. Forexample, liquid occupying the bottom of a horizontal conduit with the gas phase flowing above.

gas-oil ratio (GOR): The ratio of gas volume flow rate to the liquid hydrocarbon volume flow rate at any point, expressed at standard conditions, usually in standard cubic feet per barrel (SCF/BBL) or standard cubic meters of gas per cubic meter of liquid hydrocarbon (m3/m3).

gas volume fraction (GVF): The fraction of the total volumetric flow at actual conditions in the pipe which is attributable to gas flow, normally expressed as a percentage.

hold-up: The cross-sectional area locally occupied by one of the phases of a multiphase flow, relative to the cross-sectional area of the conduit at the same local position.

multiphase flow: Flow of a composite fluid which includes natural gas, hydrocarbon liquids, water, and injected fluids, or any combination of these.

phase: A term used in the sense of one constituent in a mixture of several. In particular, the term refers to oil, gas, water, or any other constituent in a mixture of any number of these.

pressure-volume-temperature (PVT) relationship: Application of Equations of State (EOS) to a composite fluid to calculate the change in properties in going from one set of conditions (P and T) to another.

slip: Conditions that exists when the phases have different velocities at a cross-section of a conduit.

standard conditions: A set of standard (or reference) conditions, in terms of pressure and temperature, at which fluid properties or volume flow rates are expressed.

turndown ratio: The width of the operational range of a device, and is defined as the ratio of the maximum capacity to minimum capacity

void fraction: The cross-sectional area locally occupied by the gas phase of a multiphase flow, relative to the cross-sectional area of the conduit at the same local position.

watercut (WC): The water volume flow rate, relative to the total liquid volume flow rate (oil and water), both converted to volumes at standard pressure and temperature. The WC is normally expressed as a percentage.

well trajectory: The trajectory of production parameters displayed by a well over time, sometimes shown in a flow or composition map.

wet gas: A particular form of multiphase flow in which the dominant fluid is gas and in which there is a presence of free-flowing liquid.