Shallow subsurface imaging using high resolution seismic reflection methods

Abstract

In order to evaluate the use of shallow seismic technique to map the bedrock up to the depth of 20-25 meters, three high resolution seismic reflection profiles were carried out. The data were acquired using a Strata Visor with 48-channel, 40 Hz geophones and a weight drop system as seismic source. Seismic reflection data were recorded using a CMP (common mid-point) acquisition method. The results show that the bedrock lies at about 18-25 meters depth. The bedrock related horizon observed here is of low frequency, its depth is almost similar in all three seismic lines and thus giving us the enough confidence in results and also following the subsurface structure. Reflection line 3 is been crossed by reflection line 1 and reflection line 2. To confirm the structure and same statics, I did tie these lines to confirm and the reflectors are exactly matching, hence no need to give any shifting. There is high frequency loss due to high attenuation in near surface. A good structural image of subsurface is visible from the seismic sections and for interpreter it's easy to mark structure and integrate it with other methods. With the proper equipment, field parameters and particularly great care in data collection and processing, we can image reflections from layers as shallow as 25 meters.