Extraction of Acquisition and Processing Attributes from a Time-Lapse Ocean-Bottom Seismic Elastic Finite-Difference Study

Observing changes of seismic amplitude and event timing over time within recorded seismic data are a well-established path to understanding the subtler changes to reservoir properties during injection and production phases of reservoir development. To understand the impact of acquisition tolerances and factors such as noise, ghost, and multiple energy on these reservoir changes, we must move away from real recorded seismic data and look at key issues in isolation with synthetic data.

We created a small four-component ocean-bottom seismic (OBS) data set using elastic finite-difference modelling where we have full control of the physical changes at the reservoir as well as free-surface effects and deviations from nominal acquisition geometry.

We chose elastic finite-difference modelling to include interface waves into PP and VZ data as well as to allow full modelling VX and VY components to infer 4D response from the subsequently derived radial component.

Our results confirm that geometry errors rapidly degrade the observed 4D response, but that the cumulative effect of geometry deviations, tidal statics, and water velocity corrections could also mask expected reservoir changes.