Aspects of Rock Physics in 4-D Seismology

Zhijing Wang, Steve Jenkins, Michel Bee, Michael Waite, Michael Cates, and Robert Langan

In recent years, time-lapse 3-D or 4-D seismology has been used to identify bypassed oil, to monitor steam and CO₂ injection processes, and even to track the movement of the injected water. However, the feasibility of applying seismic technology to monitoring oil recovery processes and the ability to interpret the seismic results depend to a large extent on the understanding of the physics or seismic properties of the reservoir rocks and fluids.

We have carried out several laboratory rock physics investigations on seismic properties of reservoir rocks in relation to oil recovery processes. Particularly, we found that seismic properties were dramatically affected by the injected steam in heavy oil sands, by the injected CO₂ in carbonate rocks, and in some cases, by the injected water in light oil reservoir sands.

In this paper, we present laboratory results of seismic properties of oil sands from several places in the world, including Indonesia, Canada, and California, and of West Texas carbonates undergoing CO₂ injection. We discuss the effects of reservoir geology, fluid properties, and recovery process on the seismic properties and how the laboratory results can be used in the feasibility studies and seismic interpretations. We also show examples of 4-D and cross-well seismic results from the Duri field, Indonesia, and from a West Texas carbonate field undergoing CO₂ flooding.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California