4-D Seismic Modeling for Feasibility Assessment

In many reservoirs, engineers are using 4D seismic as a reservoir management tool. With the deficiency of new oil fields in the future years, geoscientists will be called upon design and evaluate a 4D program. This research work describes the general considerations from a rock physics point of view, analyzing what specific pre-program modeling is necessary, how would you calculate the interval between time lapses to maximize impact and minimize cost, what data you would require and then specifically (quantitatively) how you would analyze the seismic response.

Based on rock laboratory measurements, correspondent to a world class reservoir rock - Berea Sandstone, a 3D geological model was built. It is a simple three layer, top shale (seal), sandstone (reservoir), and limestone (source rock), forming an anticline structure. After calculating the reservoir volumetric, the model was used as an input in a reservoir simulator. The total producing time of the field was 30 years.

With this workflow we can select a desire time stages of the reservoir, and use it as input in a full wave equation software. Then, we run an elastic seismic modeling getting the synthetic seismic response of the reservoir at the desire time.

This exercise do not focus in the specific details of the seismic acquisition aspects. Instead, it focus is the economic, rock physics parameters and fluid properties necessaries that may affect the final decision at the time to re-acquire the seismic survey. Also I consider different scenarios based on the reservoir fluid, such as gas, oil, and/or GOR.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California