Passive Seismic Monitoring

There is considerable interest in the engineering community in the real-time identification of “events”within time series data with low S/N. This is especially true for acoustic emission analysis which is utilized for monitoring and inspecting the integrity and safety of many structures such as metal and concrete bridges, gas and oil pipe lines, large storage tanks, and aerospace vehicles. A particular important application of acoustics emission analysis is within the field of passive seismology.  A passive seismic monitoring (PSM) system is designed to acquire and analyze, in real time, the acoustic signals collected by an array of appropriate seismic transducers. Seismic activity is often observed in the vicinity of underground excavations, deep open pits and quarries, around and below large reservoirs where fluids are being injected into, or removed from, permeable subsurface formations, and adjacent to the sites of large underground explosions.

Extreme examples of energy release can cause violent rockbursts resulting in fatalities and injuries among underground personnel and damage to mine structures (e.g., drifts, stopes, shafts, etc.). Passive seismic systems are capable of detecting rock failures in the vicinity of underground excavations caused by the sudden release of strain energy resulting from the redistribution of stresses around openings. Various hydrocarbon production sites also benefit from seismic monitoring systems during certain phases of production. Primary or secondary extraction or the injection of material into the reservoir to enhance production can cause significant stress changes. These stress changes can result in failures of the overlying strata and the migration of hydrocarbons to aquifers or to the ground surface. Thus PSM can be used to satisfy environmental concerns, meet regulatory requirements and assess the development of induced fracturing within the reservoir.  In addition, the passive seismic monitoring systems have been successful in identifying and locating casing failures due to steam stimulation in oil sands. During filling of hydroelectric or large irrigation reservoirs, changes in regional loading and pore pressures cause significant stress variations within the surrounding rock mass.  These can induce a wide range of micro and macroseismic events, some of which are capable of causing damage to adjacent structures or to the dam itself. PSM can locate and characterize these potentially hazardous induced events.

BCE offers state-of-the-art hardware and software solutions for PSM. These systems incorporate customized multi-channel, high bandwidth acquisition systems with advanced analytical event detection, source location, and source parameter estimation software packages. These optimal estimation algorithms incorporate data inversion, iterative forward modeling, and the relative new non-linear optimal estimation technique referred to as sequential Monte Carlo filtering or more commonly particle filtering.

Real Time Event Detection Utilizing Advanced Bayesian Recursive Estimation Techniques such as Particle Filtering

Before (event within measurement noise)

After (real time optimal event detection filter -  reference: "Baziw, E. J. (2005), "Real‑Time Seismic Signal Enhancement Utilizing a Hybrid Rao‑Blackwellised Particle Filter and Hidden Markov Model Filter", IEEE Geosci. Remote Sensing Letters, vol. 2, no. 4, pp. 1-5, Oct."):