VSP – Beyond Time-to-Depth

VSP or Vertical Seismic Profile was originally designed and is currently primarily used, to give us time-to-depth for seismic well tie. Beyond time-to-depth a number of possibilities exist. Recently, there has been considerable interest in VSP imaging, with extensive surveys being acquired both on land and offshore. Modeling studies using full-waveform finite-difference method (FDM) show us what we can image for a particular acquisition geometry and geology, with best image results seen with 3D VSP surveys incorporating a large VSP array in the well and a 2D source pattern acquired using a surface seismic shooting vessel. Traditionally, VSP imaging has been implemented using surface seismic processing algorithms. However, the VSP geometry poses its own challenges and unique opportunities. In this article we explore some imaging methods to attempt to take advantage of the VSP geometry. In addition we discuss the use of permanent in-well seismic sensors for reservoir monitoring.