From Bureau of Economic Geology, The University of Texas at Austin (
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SIPES Meeting, Austin, Texas, February 20, 2002

Are Those Extra Dimensions Worth It?
3-D and 4-D Modeling of Oil Reservoirs and Aquifers

Scott W. Tinker
Director, Bureau of Economic Geology, The University of Texas at Austin
State Geologist of Texas


Three-dimensional computer modeling was once limited to the playground of the majors, as software, hardware, and manpower requirements were prohibitively expensive for independent professionals. Technology has been evolving steadily over the past decade, and 3-D modeling tools are now fairly common in the toolkit of many subsurface geologists.

Historically, geologists have described geologic problems with 2-D renderings (maps, cross sections, tables, and graphs). The application of 3-D and 4-D (time being the fourth component) modeling tools to these geologic problems has had tremendous impact on the description and modeling of hydrocarbon and water subsurface reservoirs. In some cases, the models indicate that many of these original interpretations adequately described the system, whereas in other cases we are seeing things that we never dreamed possible.

The modeling and visualization of complex subsurface geology, combined with the ability to model the movement of fluids and gases within and through the volume, have revolutionized our understanding of subsurface behavior. Models now help oil companies extract incremental hydrocarbon reserves previously thought to be unrecoverable and help hydrologists model the volume and quality of water in aquifers to forecast future resource allocations.

I will emphasize the importance of accurate geologic frameworks in 3-D modeling and show several animated examples of 3-D hydrocarbon and aquifer models, mainly from Texas. We might even catch a ride on the back of a camcorder with a headlamp and head into the subsurface of West Texas to visit a classic Texas giant up close and personal!