Maximizing Value of Information: Real-Time Pulsed Neutron Logging Optimization for Reservoir Monitoring and Behind-Casing Opportunity Maturation

Introduction

Reservoir surveillance in mature fields faces challenges such as complex wellbore geometries, aging completions, and gravel packs, which, coupled with high E-line costs, require strategies that maximize data value. Advanced cased-hole saturation logging using Pulsed Neutron Logging (PNL) offers a solution to identify untapped reserves and assess hydrocarbon potential behind casing.

Method and/or Theory

A case study from a 40-year-old field in the Balingian basin, Malaysia, applied Pulsar* technology to evaluate two high water-cut zones and screen additional opportunities. Pulsar integrates Sigma, C/O ratio, Hydrogen Index (HI), Inelastic Gamma Spectroscopy, and FNXS for robust saturation profiling, even in gravel-packed intervals. The team executed a hybrid high-speed pass (GHS mode) for comprehensive wellbore assessment within time and cost constraints, followed by targeted low-speed passes for high-resolution data in zones indicating hydrocarbons. Real-time interpretation enabled dynamic optimization, and PNX estimates aligned closely with reservoir models, validating predictive simulations.

Conclusions

The approach identified four new oil-bearing intervals—two scheduled for immediate production (0.2 MMSTB potential) and two for future optimization—extending well life by five years. This case demonstrates the value of integrating Pulsar technology, agile workflows, and real-time interpretation to transform routine logging into a strategic, reserve-adding intervention.