Gas Lift Technique a Tool to Production Optimization

Abstract

The paramount aim of every oil and gas operator is to minimize both capital and operating costs and more importantly, maximize cumulative oil production in the most cost-effective manner for the entire field. This is to say that a true production optimization requires an operator to take a logical look at the field’s production systems from the subsurface to surface facilities. Therefore, when an oil well fails to flow naturally, it requires an assisted lifting system. Gas lift system is one of the few artificial lift methods used to start up a well and/or increase the producing life of oil and gas wells. The principle of Gas lift is by lowering the hydrostatic pressure inside the production tubing through the injection of lighter fluid into the annulus. GT oil field in the Niger Delta was used as case study; it has a production life span of eighteen years. To increase GT production and extend the lifetime of the field, the operator decided to start up an artificial lift project with an aim of optimize its production. To select the best artificial lift method to use, an economic evaluation was carried out using PROSPER for gas lift and a base case (Natural Flow) and then a production forecast with the different scenarios was performed for six years. In technical comparison, PROSPER simulation results shows that Gas lift technique gave a higher production rates when compared with the Base Case (Natural Flow), and in terms of economic comparison by considering factors like: water cut and replacement of failed pump, gas lift system was preferred for proper production optimization techniques. However, gas lift was chosen for GT based on the availability of the readily compressed gas, higher life time expectance and lower installation and operational cost as compared to other artificial lift techniques.