Improved shear wave measurements using autoseis sources

An automated impulse source (autoseis) is valuable during routine production measurements of downhole shear wave velocities (V-s) because it provides repeatable events and expedites the field testing times. The autoseis is particularly advantageous for use during seismic piezocone testing (SCPTu) and seismic flat dilatometer tests (SDMT), especially for pseudo-interval systems but also helpful for true-interval geophone measurements. Special applications rifle autoseis units includes: (1) the collection of frequent-interval V-s at 0.2-m depths compared to traditional 1-m intervals; and (2) continuous V-s measurements during constant push at 20 mm/s. Frequent-interval testing provides a better delineation V-s profiles with finer details in the profile. Continuous Vs testing reduces field testing times with increased production of results.