SEISMIC 4D FOUR-DIMENSIONAL

Three-dimensional seismic data represent static reservoir properties, because the data are collected during one instant in time. Four-dimensional, or “timelapse” seismic data, offer the opportunity to monitor the movement of reservoir fluids while they are being produced. Thus, 4D seismic measures dynamic reservoir properties. The underlying principle of 4D seismic is that acoustic properties of reservoir strata will change as a function of change in fluid content and type within the rock’s pore spaces. Thus, 3D seismic surveys that are shot in the same (or similar) manner, at the same location, and at successive times during the life of a field, record rock-fluid changes that result from fluid movement.