What is Seismic Survey?

seismic survey
                                                      Seismic Survey

I. Q: What is Seismic Survey?

A: The seismic survey is one form of a geophysical survey that aims at measuring the earth’s (geo-) properties by means of physical (-physics) principles such as magnetic, electric, gravitational, thermal, and elastic theories. It is based on the theory of elasticity and therefore tries to deduce elastic properties of materials by measuring their response to elastic disturbances called seismic (or elastic) waves.Seismic survey is the most important method in geophysical survey and the most effective way to solve oil and gas survey problems.


II. Q: What is an energy source?

A: The energy source is typically either a small amount of dynamite in a shot hole, drilled to depths of 5 to 150 feet or vibrations generated from a series of “vibroseis” trucks.


III. Q: How are the sound waves collected?

A: The reflected sound waves are detected by listening devices called geophones that are laid out along the seismic line. They are usually attached to cables, that connect into a recording truck/doghouse where the seismic data is recorded onto computers.


IV. Q: What is the difference between 2D and 3D?

A: 2D seismic lines are single lines of regularly spaced geophone stations (e.g. every 55 feet). Energy source points are established along the line typically at every 2nd or 3rd station. The same line contains recording cables and geophones as well as source points. 3D seismic programs are generally a uniform and evenly spaced grid of lines. Receiver lines containing the recording devices (geophones) usually, but not always, run in a direction perpendicular to the source lines. The spacing between lines can vary from project to project. Spacing between energy source points will also vary from project to project.