SEGJ Technical Conference

A simulation of seismic wave propagation to evaluate heterogeneous structure and near surface effects for time-lapse studies

Abstract For the time-lapse study in CCS and EOR, we have proposed the method using the seismic ACROSS (Accurately Controlled and Routinely Operated Signal System) and geophone array. However, it is considered that the near surface effects and their temporal changes caused by water content changes, temperature and surface wave generation, are very large for time-lapse estimation, in particular in time-lapse studies, and we would like to evaluate and reduce the near surface effects by the comparison of surface and borehole geophone records. We have carried out field experiment in Japan using a seismic source and simulation studies to evaluate the effects of near surface and heterogeneities such as having holes in the ground. We also evaluate the near surface effects by changing geophone depths. The result shows that if a seismic source is at the surface, the scattered wave caused by each hole is very large. Near surface source also generates very large surface waves. We will evaluate the sediment thickness by change of geophone depths.