Improving imaging and repeatability on land using virtual source redatuming with shallow buried receivers

Abstract

Time-lapse surface seismic monitoring typically suffers from different sources of nonrepeatability related to acquisition imperfections as well as due to complexity of the subsurface. Placing sources and receivers below the surface can improve seismic data repeatability. However, it is not always possible to bury a large number of sources, and therefore the next best option is monitoring with surface sources and buried sensors. We have discovered that redatuming of surface sources to the shallow buried receivers produced a reliable image of target reflectors despite the fact that receivers were placed in the near-field zone of the source. We redatumed data with the virtual source method using crosscorrelation of the measured wavefields. We found that redatuming also reduced nonrepeatability of seismic data associated with changes in acquisition geometry, variable source coupling, and daily/seasonal variations in the near surface. We developed these results with a synthetic case study using a realistic 1D elastic model with a free surface and acquisition geometry from an actual field experiment conducted in Saudi Arabia.