3D VSP Feasibility Workflow using 3D Wave Equation Modelling and Reverse Time Migration

Accurately imaging steep dip reflectors and salt boundary are very important tasks for exploration in deep water sub-salt environments where reserves are often trapped underneath overhangs of massive salt bodies. Pre-stack depth migration for surface seismic imaging has been proved to be essential for seismic exploration in such complex areas. Although they require high computing power, full two-way solutions of the wave equation -suited for such complex environments- have been used in the past few years more intensively not only for surface seismic imaging purpose but also for pre-survey modelling. With the recent development of long downhole geophone arrays, VSP techniques have emerged to complement surface seismic with improved resolution, better high dip structure definition and to fill in "imaging holes" in complex sub-salt plays where surface seismic is blind. And the recent step-change advances in computing power have made the use of full two-way solutions commercially viable as well for large VSP projects. We propose a complete VSP feasibility study workflow based on 3D wave equation acoustic modelling and reverse time migration imaging illustrated by a case study from West Africa.