Passive subsurface imaging around the KAUST shallow well site using a multi-scale seismic acquisition system

Passive seismic monitoring to assess seismic activity and analyze subsurface structures in and around well sites.

On-campus shallow monitoring well at King Abdullah University of Science and Technology (KAUST), in Saudi Arabia.

The main challenge for seismic monitoring at the site is the unconsolidated topmost layer of sand and construction debris that strongly weakens the seismic wave energy.

Researchers deployed various types of seismic sensors targeting different spatial and frequency-resolution scales to monitor seismic energy during drilling and from other random surface sources (e.g., vehicular traffic).

Four three-component broadband stations deployed over a period of 5 to 18 months before drilling and a dense array of autonomous STRYDE nodes (measuring the vertical component of the particle acceleration field), which acquired data for about one month during drilling.

The array was composed of 89 nodes with a spacing of 2 m and a total offset of 176 m. Seismic interferometry was applied on a portion of the data acquired while drilling operations were stopped (about 7 days) to synthesize surface waves and extract their dispersive behavior (i.e., dispersion curves) between 5 and 15 Hz.