Research of Improvement and Optimization of Critical Flow Rate Model in Condensate Gas Well

Abstract

Abstract Critical flow rate models are widely used for liquid loading prediction in gas wells, take Turner's model as representative, but these models only analyze critical flow rate under wellhead or bottom hole condition, and take surface tension as constant, which results in a relatively large deviation between prediction result and actual liquid loading condition in condensate gas wells. In order to increase precision of liquid loading prediction, critical flow rate models are improved, aiming at solving above-mentioned problems. Different distribution of critical flow rate and surface tension along wellbore are considered, and the largest value of critical flow rate is taken as criterion of liquid loading condition, surface tensions under different temperature and pressure conditions are also calculated. Besides, on the basis of analyzing temperature and pressure distribution in dry gas wellbore by using temperature and pressure coupling method, a reasonable temperature and pressure coupling calculation model for condensate gas well is established, which considers the actual situation that both condensate and formation water exist in wellbore and revises relative density and flow rate of gas accordingly. Through verification by field case, it can be seen that precision of liquid loading prediction of improved critical flow rates models increases compared to that of original models, amongst which the precision of and the increased range of precision of liquid loading prediction of improved Li Min's model is highest. Therefore, the improved Li Min's model is the most suitable model for liquid loading prediction in condensate gas well.