Abstract: Gas reservoirs in the East China Sea gas fields,which operated by water flooding,are commonly developed.Some gas wells produced along with water,the water/gas ratio of which are high.The traditional two-phase flow wellbore pressure calculation methods were employed to predict wellbore pressure distribution.However,it was found that the current models suffer from low prediction accuracy,which affects the diagnosis of liquid loading conditions in gas wells and the selection of drainage and production measures.To address this issue,gas-liquid two-phase flow patterns under different well diameters,inclinations,and water/gas ratios were analgzel and,a new flow pattern discrimination method suitable for high water/gas ratios was derived based on the discrimination model by corrected Kaya flow pattern.Additionally,the empirical coefficients related to the Mukherjee-Brill liquid holdup calculation formula were revised.Introducing dimensionless parameters characterizing the water/gas ratio and angular correction factors.On this basis,a new pressure drop model applicable to high water/gas ratio gas reservoirs was established.The research shows that the new liquid holdup calculation model achieves an average calculation error of less than 15% for liquid holdup under different pipe diameters and inclinations.The new wellbore pressure drop calculation method improves the prediction accuracy of wellbore pressure in water-injected gas wells in the East China Sea by over 50%,with an error not exceeding 8% compared to measured values.The new method has significant application value for predicting the pressure distribution of two-phase flow in high water/gas ratio gas wells and is of great guiding significance for optimizing operational systems and selecting drainage and gas production processes in the middle and later stages of water-drive gas reservoir development.

Key words: gas well, high water/gas ratio, inclination, flow pattern, liquid holdup, pressure distribution