What Seismic Exploration is
One of the biggest breakthroughs in natural gas exploration has come through the use of basic seismology. Seismology refers to the study of how energy, in the form of seismic waves, moves through the earth's crust and interacts differently with various types of underground formations.
The basic concept of seismology is quite simple:
A. The earth's crust is composed of different layers, each with its own properties. Energy (seismic waves) traveling underground interacts differently with each of these layers.
B. Transmitted from a source, these seismic waves travel through the earth, and are reflected back toward the source. Each underground layer reflects the waves in a different direction, depending on the makeup of the layer.
C. This reflection allows for the use of seismology to identify the properties of underground geology. Geophysicists are able to artificially create vibrations on the surface and record how these vibrations are reflected back to the surface.
How Seismic Exploration is used
Using seismology for the exploration of natural gas involves artificially creating seismic waves, the reflection of which are then picked up by sensitive pieces of equipment called “geophones,” imbedded in the ground.
The data picked up by these geophones are then transmitted to a seismographic recording truck, which records the data for further interpretation by geophysicists and natural gas reservoir engineers. This information can then be analyzed to determine the locations of natural gas, as well as how to most effectively extract the gas.
3-D Seismic Imaging
3-D imaging utilizes seismic field data to generate three dimensional “pictures” of underground formations and geologic features. 3-D seismic allows geophysicists and geologists the opportunity to study the composition of the earth's crust in a particular area.
This is extremely useful in the exploration of natural gas, as an actual image can be used to estimate the probability of formations existing in a particular area and the characteristics of that potential formation. This technology has raised the success rate of exploration efforts. In fact, the use of 3-D seismic has increased the likelihood of successful reservoir locations by up to 50%.
By providing data about the location of natural gas reservoirs, 3-D seismic imaging ensures more accurate placement of drillsites and results in more productive wells.