Operation features of a narrowing device in separationless three-phase flow-meter

Dual-Isotope Spectrometric Gamma Densitometer for Diagnostics of Three-Phase Oil–Water–Gas Flows

“…cubic parabola, given, e.g., in [5], where I i s the measured intensity of the passed gamma radiation, while the indices g and w refer to gas and water and Q is the volumetric flowrate.…”

“…While creating these GDs, a relation for error determination, e.g., the water cut of the oil-water mixture [6], serves useful purposes: (5) where d is the inner tube diameter; μ 0 and μ w are the linear absorption coefficients for oil and water, respectively; t is the time of measuring; and N* is the number of photons per unit time at the detector input. This relation is derived for quasi-stationary flows with stratified or annular flow regimes [6] under the condition that an error is determined only by a statistical error.…”

“…While creating experimental GDs for the diagnostics of three-phase oil-water-gas flows, the specifics of requirements for a measuring system should be taken into account. This system must ensure measuring temperatures T of the flow and the flowmeter housing, flow pressure P, and pressure drop ∆P through the ND; it must respond to possible oscillations of parameters in flows with gas [5,7] and average the measured parameters; it must implement a rather complex algorithm for processing the primary signals of the system for the purpose of obtaining the soughtafter quantities of the component composition and flowrates of three-phase flow components; and it must transmit information to a certain server using the ( )…”

“…1. Because in the test-bench room, the temperature should change not frequently and not considerably, the temperature compensation of the NaI response whenever required was performed manually by chang- [5,7] as aids for the diagnostics of two-phase flows of oil-stratal water, exxsol-water, water-air, and the liquefied natural gas (LNG). In particular, the system of diagnostics of two-phase oilsaltwater flows on the basis of the 137 Cs isotope and a conical ND satisfies the GOST requirements [8] within the w range from 0 to 95% [7].…”

“…The composition of the three-phase flow components ϕ, w , and α is determined by three relations which are obtained on the basis of process descriptions, e.g., in [2] as functions of linear coefficients of absorption of gamma quanta with two different energies of photons in gas, water, and oil, as well as intensities of gamma rays (initial and passed through the flow) with two different energies, where ϕ = A g /(A g + A l ) is the actual volumetric gas content, A is the cross-sectional area, the indices g and l refer to gas and liquid, w = (ρ -ρ o )/(ρ w -ρ o ) is the volumetric water cut, ρ is the average density, the indices w and o refer to water and oil, and α = (1 -w -ϕ) is the volumetric oil content. To determine the volumetric flowrate of the mixture Q, a narrowing device is used, which operates in accordance with the fourth simplified relation with the horizontal orientation of the multiphase [5]: ΔP = ξ -2 ρQ 2 + ΔP fr , where ΔP is the measured full pressure drop on the narrowing device, which is composed of the drop in hydrodynamic pressure ΔP hd = ξ -2 ρQ 2 due to the flow narrowing in the ND, estimated from the Bernoulli law under the assumption of the zero flow viscosity, and the frictional pressure drop is ΔP fr ; ξ = A 1 A 2 [2/( )] 1/2 is the geometric parameter of the ND, and A 1 and A 2 are the larger and smaller cross sections of the conical ND. The influence of the latter component is more significant the higher the flow viscosity is, which is especially typical for oil, whose viscosity is several times more than that for water.…”