Articulo tecnico sobre medidor multifasico

MULTIPHASE FLOW METERING AN EVALUATION OF DISCHARGE COEFFICIENTS J.A. AJIENKA O. E. ENAIBE O.O. OWOLABI

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JCPT94-08-07 Multiphase Flow Metering: An Evaluation of Discharge Coefficients J.A. AJIENKA, O.E. ENAIBE University of Port Harcourt O.O. OWOLABI The Pennsylvania State University where required 1. 9" (' ,d ....................................................................... (2) it is known that of prediction of cn'tical [P (@iL, + p,LGRI)l ................................................................... (3) answered are how do we ent for multiphase flow 0.00504 z, T, (R - R,) meterin fficient for critical (B,, + 1) + rnuitiph 1.) R Figu presented with which4 ,B,, + WOR)+ 0.0 353 g R.................................(4) me@ to obtainactual- multiphase ft both cn'tical and subcritical flows. It is P2 shown that CD for multiphase critical flow cannot be the saine Letting to be equal to X, then:. for multiphase subcritical flow. P, k k Introduction LGR, (i -- X) + _Xk - 1 P2 k-I Multiphase flow is a complex phenonienon: As a result the F majority of published correlations are highly empirical. This affects the general validityof these correlations for all ranges of 1,GR, , x k I fluid properties as they are limited to the quality and scope of the .....................(5) data base from which they are developed. Therefore, correlation which performs well within the range ol' data Llsed to develop it. 5.615 (B @ +WOR) may fail outside this range, l@GR, B,, (R - Rs) Multiphase flow through restrictions is usuallyevaluated under ....... ... I.....................................................(6) critical or subcritical flow conditions. As a standard oilfield pracFlow is critical if the pressure ratio (X = X,) is equal to the critical tice, wellhead flow performance is evaluated under critical flow pressure i-atio. Otherwise. flow is subcritical. while flow performance through subsurface chokes and safetyAshford's analytical correlation for critical flow is given bv: valves is done through subcritical flow. Critical or sonic flow is flow in which downstream pressure and temperature perturbations _ are not transmitted upstream to affect the fl(lw rate. unlike in sub0. S58 C 3,,d2 critical flow. q,, Available critical multiphase orifice ilo'A correlations can be v + 0.56 categorized as follows(l): P, I .Analytical models, applying mathematical analysis based on fundamental principles, to a siiiipiified physical inodel with A'+O.76 P, 2 the development of equations. 2 Empirical correlations using diinensioli@ll analysis to select (B'+O.01353yg R)+( I B'+O.01353,y, R,) ............... 11.........(7) and group the most important variables. 3. Empirical correlations from field oi- laboratory data.where Examples of category I correlations are those of Tangren et A'= 5 04 x i(I-3 Tiz, (R -- Rs) al.(2), ROS(3), Poettmann and Beck(4), Ashl'ord(51. a generalized .............................................................(8) model by Ajienka(6) and Ajienka and IkokU(7). The simplified form of the generalized model applicable to both continuous liquid B'- 6 .4(,y(, +,y@ WOR) phase flow andcontinuous gas phase t'low is given by Equation ....................................................................(9) P, (B,, + 'A'OR) (10) qTP = f b@,R.PF .......... P, ....................... ....................................... 11................................ (1) Whilc the earlier analytical models assume that critical flow October 1994, Volume 33, No. 8 57

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MuItiphase Flow Metering: An Evaluation of Discharge Coefficients
J.A. AJIENKA. O.E. ENAIBE
University of Port Harcourt

0.0. OWOLABI
The Pennsylvania State University

Abstract
The orifice discharge coefficient (Co) is the constant required to correct theoretical flowrate to actual...