Successful Wellbore Fluid Unloading Using Locally Manufactured Swab Cups for Underbalance Perforation: Swabbing Operation Case Study from the Nubi-Mahakam Field, Indonesia

Abstract This paper discusses a successful approach to unloading wellbore fluids using locally manufactured swab cups for underbalance perforation, based on operational practices from the Nubi-Mahakam Field, Indonesia. In oil and gas reservoir development, the accumulation of liquid in wells is a common challenge that must be addressed before initiating production. This is particularly relevant in the Mahakam Work Area (WK Mahakam), where liquid lifting operations are routinely performed. These operations include, but are not limited to, liquid lifting from new wells before the first perforation, after heavy intervention operations like sediment washing or cementing, and from dead wells due to natural liquid accumulation from the reservoir. The method involves using a swab cup device lowered into the well using slickline, allowing liquid within the well to be lifted out. This technique effectively unloads wellbore fluids, creating the necessary conditions for underbalance perforation. The use of a locally manufactured swab cup, designed with a high-grade rubber material, has shown impressive results, with an efficiency rate of 91% and a cost of less than USD 10,000 per well. This approach has successfully unlocked marginal reserves in several wells within the Mahakam Field. This case study demonstrates the viability of swabbing operations as a cost-effective alternative to coiled tubing for unloading wellbore fluids to achieve underbalance perforation, particularly in fields with marginal reserves. By utilizing locally manufactured equipment, which can be produced more quickly and at a lower cost, the efficiency of the operation is significantly improved, providing a reliable solution for future well interventions in the Mahakam Field.