Pulled array seismic (PAS) – A new method for shallow, high-resolution reflection seismic data acquisition

Along with the increasing demands in Denmark for new and deeper groundwater resources, the application of shallow reflection seismic methods has been intensified. While the traditionally low-priced and extensively used electric and electromagnetic methods are used successfully for mapping of the more shallow geology, reflection seismic is an ideal method for mapping of deep (up to several hundreds of metres) buried quaternary valleys and deep tertiary (Miocene) aquifers as well as faults. The cost for carrying out shallow onshore reflection seismic surveys has, however, been a limiting factor towards the use of seismic data in mapping of groundwater resources. Previously, results using a towed land streamer with gimbal mounted geophones and a pipe gun or sledgehammer as seismic source, has been presented by van der Veen and Green, 1998 and van der Veen et. al. 2001. RAMBOLL has developed a new method for shallow reflection seismic data acquisition called Pulled Array Seismic or PAS using a towed trail of conventional geophones and a seismic vibrator as energy source. The new method is considerably faster and more cost-effective compared to traditional shallow reflection seismic data acquisition, and the data quality is fully comparable also to deeper conventional seismic data. Since the first commercial data acquisition with this new method took place in August 2000 there has been a substantially interest for the method. RAMBOLL has thus acquired 106 km of Pulled Array Seismic on 28 lines for 6 different clients in Denmark and southern Sweden.