Reservoir Monitoring in Complex Borehole Environment – Gas field Case Studies in Nam Con Son Basin

Effective reservoir management in mature gas-condensate fields necessitates close and accurate monitoring of formation fluid saturations, particularly under complex completion scenarios and variable borehole fluid compositions. Traditional pulsed neutron logging (PNL) tools often fall short, leaving room for uncertainty in fluid saturation analysis. To address these challenges, a new generation of PNL tools has been developed; engineered with self-compensated and enhanced measurements, these tools redefine reliability in gas saturation evaluation. From 2019 to 2025, this technology was deployed across several aging wells in Nam Con Son Basin—wells that had been producing since the early 2010s and recently faced rising water production and shifting gas-water contacts (GWC). Through time-lapse logging, the tool enabled accurate tracking of GWC movement, empowering timely interventions and smarter reservoir decisions. Case studies reveal its resilience in complex environments, delivering high-confidence saturation data that directly fed into updated reservoir simulation models and optimized management strategies.