Whole wellbore liquid loading recognition model for gas wells

Abstract

Liquid loading is a serious issue in the production of gas wells. In order to recognize liquid loading, the flow regime and the transition criteria of the gas-liquid two-phase in the wellbore were obtained by theoretical analysis. The prediction correlation for the size of the entrained droplet was given for every flow pattern. Based on the force balance condition of the largest droplet in the gas core, the dimensionless critical gas mass flow rate was defined to recognize liquid loading along the whole wellbore. The influence of different factors on liquid loading was analyzed by an example. The results show that there are three kinds of flow regime in the wellbore, which are co-current annular flow with disturbance wave torn off, co-current annular flow with bag breakup and churn-annular flow with wave under-cut. The maximum size of the droplet in the gas core depends on the droplet breakup process under co-current annular flow and droplet entrainment process under churn-annular flow. The dimensionless critical gas mass flow rate decreases with the increase of gas flow rate and the decrease of tube diameter, which reduces the possibility of liquid loading. Liquid loading can be avoided by the decrease of surface tension. The viscosities of the gas and liquid phases have slight influence on the dimensionless critical gas mass flow rate.