Passive Seismic Monitoring of Induced Seismicity from Hydrocarbon Production Operations in the Niger Delta

This study develops an original passive seismic monitoring and induced seismicity characterisation framework for hydrocarbon production operations in the Niger Delta, addressing a significant gap in the understanding and management of reservoir-induced seismicity in Nigeria. Induced seismicity from oil and gas operations including fluid injection, production-induced pore pressure changes, and reservoir compaction is a global concern with safety, regulatory, and community impact implications. The Niger Delta's complex fault system, significant hydrocarbon production, and dense human settlement create conditions where induced seismicity monitoring and assessment are critical but largely absent. This study designs, installs, and operates a seismic monitoring network comprising 12 broadband seismometers deployed around three producing fields in Rivers and Bayelsa States for a 30-month monitoring period. A calibrated detection threshold of magnitude 0.5 is achieved. Microseismic event cataloguing uses waveform cross-correlation detection and S-P arrival time differential location methods. A full moment tensor inversion methodology is developed for the Nigeria production geology context to characterise fault activation mechanisms. Statistical time-series analysis tests for temporal correlations between production-injection operations and seismic event rates. Findings reveal 1,284 microseismic events of magnitude minus 0.2 to 2.8 over the monitoring period, significantly more than recorded in the national seismic catalogue. Event clustering is spatially correlated with mapped faults on the flanks of producing structures. A statistically significant correlation between water injection volume and increased seismic event rate is demonstrated at one field with a 3-week lag. The study provides an original monitoring and attribution framework for Niger Delta induced seismicity and recommends the monitoring network be expanded as a regulatory requirement.

Keywords: passive seismic monitoring, induced seismicity, Niger Delta, microseismic, hydrocarbon production.