Seismic imaging using an e-vib: A case study analyzing the signal properties of a seismic vibrator driven by electric linear synchronous motors (LSM's)

Seismic imaging characteristics of a prototype electrically driven, linear synchronous motor (LSM) based, vertical-force seismic vibrator (“e-vib”) were evaluated at a site in the Netherlands. The system weighs 1.65 t and excites seismic signals with a peak force of 6.7 kN. Data were recorded along two collocated geophone based-nodal and landstreamer MEMS-based (micro-electromechanical sensors) 2D seismic profiles. To obtain a broad bandwidth dataset, the e-vib operated with a 1-200 Hz linear sweep. Shot gathers of the merged nodal-landstreamer dataset show good quality seismic data of a broadband nature. The processed merged dataset demonstrates high-resolution reflections of the stratigraphic members from approximately 200 m to 2 km, with visible reflections as deep as 2.5 to 2.9 km. As a reference, we also processed a legacy 3D microspread dataset acquired at the same site with a magnitude stronger (14.1 t, 67.5 kN) hydraulic vibrator. Comparison of our nodal-landstreamer seismic section versus 2D slices extracted from the processed microspread volume suggests similar signal penetration depth and same key marker horizons seen in both. Analysis of the reaction mass and base-plate accelerometer signals recorded with the e-vib source operating both on grass and asphalt surfaces shows that the e-vib has low total harmonic distortion. The results obtained indicate that, although relatively small, the e-vib is capable of generating high-quality, broadband seismic data