Patent RU-2695957-C1 (RU)
Title: Method of determining volume fractions of water and free gas in a stream of crude oil and a measuring system for its implementation
Inventor: ANIKIN PAVEL VLADIMIROVICH
IPC: G01F1/74
Filed: 2018-11-29
Granted: 2019-07-29
Abstract: FIELD: oil and gas industry. 
     SUBSTANCE: invention relates to a method and device for continuous determination of flow parameters of a mixture and is intended for use in oil and gas industry. Method of determining volume fractions of water and free gas in a stream of crude oil includes passing a stream of crude oil in form of an oil and gas mixture through an ejecting channel formed by the surface of the streamlined body with serially converting flow zones: a channel narrowing region accelerating the transmitted stream; a zone which stabilizes the flow velocity of the flow with a constant cross-section of the channel corresponding to the dimensions of its narrowest cross-section; and a channel expansion zone which reduces flow rate of flow, as well as continuous measurement of the crude oil flow by the sensors of the frequency characteristic and subsequent determination of the content of water and free gas in it by calculations, additionally before passing the flow of crude oil through the channel narrowing zone, it is homogenised, and after moving of the flow into the channel expansion zone, it is decelerated with provision of gravitational separation of the heavy fraction of crude oil in form of a mixture of oil and water, and this separated heavy fraction of crude oil in form of a mixture of oil and water is fed into separate flow chamber formed in the ejection channel with reverse passive circulation of mixture, wherein continuous measurement of frequency characteristic of crude oil dielectric permeability is subjected to both its total flow in zone with constant cross section of channel corresponding to dimensions of its narrowest cross section, and flow of its heavy fraction in form of mixture of oil and water, and each current value of frequency characteristic of dielectric permeability of oil-water mixture is used to calculate volume fraction of water and free gas in crude oil, wherein volume fraction of water in crude oil is calculated by formula: 
     
       
     
     where: W is water volume fraction in heavy fraction of crude oil flow with predominant filling with oil/water mixture, %; f w  – frequency of moisture content sensor during calibration by water, Hz; f n  – frequency of moisture content sensor during calibration by oil, Hz; f wn  – current value of moisture content sensor frequency for water-oil mixture, Hz, and volumetric fraction of free gas in crude oil is calculated by formula: 
     
       
     
     where: G is volume fraction of gas in light fraction of crude oil flow with predominant gas filling, %; f G  is the gas content sensor frequency during air calibration, Hz; f Gwn  – current value of gas content sensor frequency in OGWM, Hz; f wn  – current value of moisture content sensor frequency for water-oil mixture, Hz; as well as a measurement system for realizing said method. 
     EFFECT: reduced error of determination of volume fractions of water and free gas in crude oil flow. 
     3 cl, 4 dwg