Publications

Depletion of the reservoirs leads to a decrease in production rate and continuously drops below its minimum critical velocity. At this point, the liquid which flows vertically upward with gas begins to fall back into the wellbore. Liquids accumulation in the tubing creates additional pressure drop and gives more restriction for gas in the reservoir to come into wellbore. At a certain point the well will cease to flow at all. Smaller diameter tubing string (so-called, velocity string) installation is one of methods applied in Semberah to overcome liquid accumulation in wellbore of low production gas wells. This paper explains the success application of velocity string project in the observed field. Furthermore, velocity string selection candidate and design were examined to have better understanding of velocity string performance. Well selection included identification of well behavior, evaluation of surface back-pressure, and production tubing size. Inflow and outflow performance was matched with actual data prior to detail assessment for the installation. A good understanding of comprehensive well selection is an important factor to have a success of velocity string installation project. Low-cost yet effectively maintaining base production application is demonstrated through this project. A successful application of velocity string in observed field may encourage application of low-cost deliquification methods in other fields to prolong well production life. Keywords: velocity string, liquid loaded gas well, deliquification