Seismic Imaging

(advances in seismic-imaging computers are finding more energy sources)

One of the important new tools for geologists is the three-dimensional seismic-imaging computer

With great effort and cost, a Russian drilling crew shipped a rig into an Arctic swamp far north of Moscow and drilled for weeks through rock; only to find more rock. After eight dry holes in 2002, they gave up.

In 2004, a team of geologists returned to the site, this time with three-dimensional seismic imaging computers, and placed the rig with pinpoint accuracy over what is now the commercially productive Val Gamburtseva deposit.

Searching for untapped reserves, geologists must venture into environments ever more remote and hostile to industrial development. Russia will need ice-capable offshore platforms, undersea pipelines, seismic imaging and modern techniques like horizontal drilling.

—Excerpts from "Looking to the West for new tools of the trade"
by Andrew E. Kramer; International Herald Tribune, page 16; April 10, 2006.

How seismic-imaging functions

There are two types of seismic images produced as the sound waves travel into the ground. Reflected waves travel downward, bounce off a layer or object in the soil or rock and return to the surface. Refracted waves are those which travel downward then turn at a geologic boundary, such as the surface of a rock layer, and travel along it before returning back to the surface.

Reflected waves generally show more subsurface detail. However, multiple “echoes” can make reflections very difficult to interpret. Refracted waves are typically used to profile shallow bedrock; that is, rock less than 100 feet below the ground.

Seismic exploration is the use of seismic energy to probe beneath the surface of the earth, usually as an aid in searching for economic deposits of oil, gas, or minerals; but also for engineering, archeological and scientific studies.

In exploration seismology, the seismic method is applied at or near the earth's surface to measure the elastic properties of the subsurface and to detect variations in those properties. Variations and discontinuities in subsurface elastic properties may be indicative of changes in lithology or pore fluids.

Seismic exploration is the use of seismic energy to probe beneath the surface of the earth, usually as an aid in searching for economic deposits of oil, gas, or minerals.

Exploration seismology has been applied for subsurface investigations of depths as great as 150 km; however, it is particularly useful for depths up to 10 km. For these depths, the seismic method is capable of detecting and spatially resolving features at scales as small as tens of meters or less.

This resolving power is significantly finer than the resolving ability of other remote geophysical methods for this depth regime. Because this region of the earth's subsurface includes nearly all of its oil and gas reserves, exploration seismology plays a prominent role in the energy industry.

Fast, accurate imaging of complex, oil-bearing geologies, such as overthrusts and salt domes, is the key to reducing the costs of domestic oil and gas exploration. Geophysicists say that the known oil reserves in the Gulf of Mexico could be significantly increased if accurate seismic imaging beneath salt domes was possible.

A range of techniques exist for imaging these regions, but the highly accurate techniques involve the solution of the wave equation and are characterized by large data sets and large computational demands. Massively parallel computers are necessary to provide the computational power for these highly accurate imaging techniques.

Pointing to a page about seismic imaging The unit of seismo-, -seismic words are available.