Survival Analysis of Matrix Bypass Events in West Sak

Summary

This project applied survival analysis to Matrix Bypass Events (MBEs) in the West Sak reservoir on Alaska’s North Slope, which cause catastrophic increases in watercut and require costly well interventions. The analysis aimed to identify factors influencing the likelihood and timing of MBEs, including producing layer, well configuration, and reservoir management practices, to support more effective waterflood operations and long-term recovery.

Project Highlights

• Conducted survival analysis on historical MBE data to quantify risk factors and event timing
• Assessed the impact of producing layer, horizontal/vertical well configurations, and producer-injector patterns on MBE likelihood
• Revealed that layer effects were dominant while gradient/voidage effects from previous studies were not reproducible after accounting for other factors with a robust statistical analysis
• Provided actionable insights to reservoir engineers, supporting discussions on waterflood management and guidance

Technical Innovation

• Leveraged advanced survival analysis techniques to model time-to-event data for MBEs
• Integrated well configuration and reservoir management variables to isolate key contributors
• Automated data preparation and analysis for rapid scenario evaluation

Impact

The survival analysis clarified the primary drivers of MBEs in West Sak, showing that specific layers were much more likely to experience early events, while previously assumed benefits of voidage replacement and gradient management were not supported after controlling for other factors. Although engineering guidance on pressure gradients was not changed, the results provided valuable context for reservoir engineers, enabling more informed waterflood management and intervention planning.