Patent ID: 6546809
Filing Date: 2003-04-15
Classification: E21B,G01F

Abstract:
Method for the measurement of the liquid and gas flow rates QL and QG in a multiphase fluid stream flowing in a conduit (2) and having an overall flow rate Q, comprising:withdrawing a portion of the overall flow rate Q of said stream from a section of area A1 in which substantially isokinetic conditions are established, at a sampling section of area A2, A2 being a fraction of A1; separating out said withdrawn portion of fluid stream into single liquid and gas components; measuring the liquid and gas flow rates qL and qG forming said withdrawn portion of fluid stream and calculating their sum q; obtaining pressure signals to measure the pressure drop &Dgr;p occurring in said fluid stream in at least one of a first constricted section (3) and a second constricted section (4) located upstream and, respectively, downstream of said sampling section; from said pressure drop &Dgr;p calculating the overall flow rate Q, or at least the flow rate QG of the gas fraction thereof, flowing in the corresponding constricted section, on the basis of the relation &Dgr;p=&agr;Q2, &agr; being the calibration coefficient of the constricted sections; calculating the ratio between the flow rate value obtained from said relation and the flow rate q of said withdrawn portion, to verify that it is at least approximately equal to ratio A1/A2; varying the sampled portion flowrate if the ratio between the overall flowrate to the withdrawn portion flowrate is not approximately equal to A1/A2 and repeating the measure; and, calculating the overall liquid and gas flow rates QL and QG from the liquid gas phase flow rates qL and qG in said withdrawn portion from the relations QL=(A1/A2).qL and QG=(A1/A2).qG.