Ambient Seismic Monitoring - Global Geophysical Services
Ambient Seismic Monitoring
Global’s ambient seismic monitoring directly images acoustic activity in the subsurface. The method images rock volumes that are acoustically active under naturally occurring conditions, under hydraulic stimulation or during production-related activities. Monitoring can be performed before, during and after stimulation providing knowledge of natural fractures, faults, stimulated rock volume and the active production volume.
Ambient seismic monitoring provides valuable predrill information for exploration and development planning. Ambient seismicity during this period is the earth’s natural, continuous background seismicity. Ambient images reveal fracture zones and volumes of rock that are likely to have high hydraulic conductivity/fracture permeability. In projects to date, high-activity fracture zones and rock volumes seen in predrill ambient images are correlated with areas of increased production in conventional fractured reservoir plays, zones of fluid loss during drilling, low fracture treating pressures, and the potential for fracture hits on adjacent wells.
During a frac, fluid pressure and stress changes illuminate fracture fairways over large areas. These signals are recorded continuously throughout the entire duration of the frac and are used to directly image the fracture networks activated by pressure changes. Monitoring during fracturing provides direct images of the Stimulated Rock Volume (SRV), the main induced fracture surfaces, and the natural fracture network stimulated by fracturing. The SRV reveals induced fractures and stimulated natural fractures as complex surfaces and networks.
This type of frac monitoring images the effect of stimulation and shows the progression of fractures opened during the frac’ing process, providing completion engineers with the insight needed to guide drilling decisions and improve frac designs.
An Active Production Volume is similar to an SRV but is an image of the reservoir volume that is seismically active during production. The same imaging methods are applied weeks, months or years after stimulation to image the fracture networks and the APVs. Active production volumes can be computed for producing wells from ambient seismic data recorded in times when there is no frac’ing. This monitoring images the volume directly connected to the wellbore while the well is in production. Monitoring production volumes periodically over time allows for identification of missed pay, planning for intervention on existing wells and planning for infill drilling.
Global’s ambient seismic monitoring allows you to discern the impact of both natural and induced fractures and to determine the cumulative affect they have on actual well productivity.