Prediction of Liquid Loading in Gas wells

Abstract

Abstract It is a well known fact that the hydrocarbon demand increases by the day. Now, in order to meet this ever increasing demand it is essential for us to produce at the required rate over a specified period of time. The most prominent problem affecting production in gas wells is Liquid Loading. It is basically the inability of gas to remove liquids being produced in the wellbore. This occurs when the velocity of gas being produced falls down a particular value known as "critical velocity". The produced liquid will accumulate in the well creating a static column of liquid, therefore creating a back pressure against formation pressure and reducing production until the well ceases production. This problem should be predicted early and dealt properly to prevent economic losses and produce efficiently. Some notable correlations that exist for predicting the critical rate required for liquid unloading in gas wells include Turner et al., (1969), Coleman et al., (1991), Nosseir et al. (1997) and Li et al. (2001). However, these correlations offer divergent views on the critical rates needed for liquid unloading and for some correlations in particular, at low wellhead pressures below 500 psia. In this paper, we compared the critical velocity graphs obtained from different models for four different wells and concluded that Turner model gives the most conservative value of critical velocity of all the methods for any value of pressure. The turner model is most widely used and accepted in oil and gas industries and moreover all the theories are based on the Turners model. Using Nodal Analysis we integrated IPR and TPR curves to find out the operating point of the wells. Then by intersecting turner model curve with the future IPR curves we predicted the year in which the problem of liquid loading may occur. This will help us in taking necessary precautions beforehand. After liquid loading has occurred, there are different deliquification techniques to deload the well. They have been presented in this paper, which help in reinitiating gas production.