An investigation of wet gas over-reading in orifice plates under ultra-low liquid fraction conditions using dimensional analysis

• Dimensional analysis was used to establish the wet gas over-reading correlation in orifice plate.
• The correlation was used for the non-separation measurement of wet natural gas with liquid fraction lower than 0.5%.
• The relative deviation of this correlation is better than ±2% in experimental verification.

Wet gas represents a special gas-liquid two-phase flow case which is often encountered in the oil and gas industry, such as wet natural gas extraction from a condensate field. The on-line, non-separation measurement of wet gas under ultra-low liquid fraction conditions is an important research area that presents significant technical challenges. In this paper, a method based on dimensional analysis is investigated that may enable predictions of the over-reading parameter in wet gas with liquid fractions less than 0.5% using non-separation measurement. A standard orifice plate with a diameter of 50 mm and a beta ratio of 0.55 was used as the flow measurement device. The dimensional analysis method was used to investigate the flow characteristics of a wet gas flowing through an orifice plate for Lockhart-Martinelli parameters ranging from 0 to 0.08, gas Froude numbers ranging from 0.5 to 2.4 and liquid gas density ratios ranging from 75 to 170. A measurement-based correlation of the wet gas over-reading parameter in an orifice plate is derived using dimensionless parameters combined with physical analysis. The experimental data shows that the relative deviation of this correlation is less than ±2% in experimental verification. The results of this study show that this method can be applied to the non-separation measurement of wet natural gas from the ultra-low liquid fraction of an oil and gas field in the future.