TECHNICAL AND ECONOMICAL EVALUATION OF THE DELIQUIFICATION METHOD FOR GAS WELL(SS7) IN THE SONGO SONGO GAS FIELD

Abstract

This study was conducted to investigate the most suitable deliquification method for removing the accumulated liquid from the well SS7 to surface. This study began by determining different sources of liquid into the well SS7 and then predicting liquid loading problem. The identification of liquid sources in the well SS7 was performed using correlations and identified the contribution of both liquid from condensation and coning water to the produced liquid from the well SS7. Liquid loading prediction was performed using Turner droplet model and the system performance curve developed in Prosper software. Both of the two alternatives predicted the existence of liquid loading at the current producing period (2016) in the well SS7. The predicted liquid loading in the well SS7 gave the challenge which leads to the new study of finding the best alternative of removing the accumulated liquid to surface and increases gas flow. Several liquid unloading method were evaluated both technically and economically to find the best alternative which can be proposed for SS7. Technical factor selected Gas lift, Plunger lift, Velocity string and ESP as the most effective method in accordance with the SS7 conditions. The selected methods by technical criteria were further evaluated considering the economics factors to find out which among the four selected method gave positive NPV. The results from economical evaluation selected Plunger lift, Gas lift and ESP as the most suitable method for SS7 because they generated the positive NPV. Final decision was performed based on the magnitude of the generated positive NPV which leads to the selection of Plunger Lift to be the optimum method for removing liquid from the bottom of the well SS7. An engineering design of the Plunger lift operating parameters for lifting an average liquid of 122STB produced from well SS7 was performed. The estimated parameters were, maximum and minimum casing build up pressure 1442 psia and 1199 psia respectively. The other parameter calculated were the minimum gas rate per cycle of 15Mscf/day required to lift the Plunger and the liquid above it to surface and the maximum number of cycle required per day were 149 cycle/day.