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Breaking the seismic 4D ‘image’ paradigm of seismic monitoring

 

Habib Al Khatib*, Yessine Boubaker* and Elodie Morgan* present a focused 4D seismic monitoring method that predicts the optimal source and receivers’ location for the monitoring of strategic areas.

Seismic imaging techniques were designed for exploration. To better image the subsurface, the industry developed high-resolution 3D seismic monitoring methods which used systems able to record hundreds of thousands of channels simultaneously. In the 1990s when the need for reservoir monitoring appeared, repeating the seismic image over time was a natural progression and delivered high quality results. Later, to increase the detection threshold, expensive permanent systems have then been installed enabling a world record detection threshold levels.
Yet, since then, improvements in seismic structural images combined with reservoir dynamic simulations provide more accurate predictions. With reduced uncertainty, lighter seismic monitoring approaches could be considered: focused seismic monitoring could provide more frequent observations at strategic subsurface locations to rapidly validate or invalidate flow simulations.
In this article we present a focused 4D seismic monitoring method that predicts the optimal source and receiver locations for the monitoring of strategic areas, capitalizing on existing 2D/3D seismic and reservoir knowledge. Such a light acquisition set-up using conventional equipment is agile enough to enable frequent detections of changes in several locations. The method is illustrated using two field cases that show excellent correlation results with observation well data which illustrate a better reservoir understanding of dynamics arising from our approach.

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