Seismic reflection surveys provide explorers with structural images of the sub-surface. The delivered product of a seismic reflection survey is a sub-surface profile image where the vertical axis is seismic wave travel time or, in cases of advanced processing, depth. The product allows the explorer to better determine geological structures such as unit boundaries, faults and folds. Depending on the objective of the survey, more information is incorporated in order to make decisions on further exploration activities.
In effect, seismic reflection surveys produce 2D profiles or 3D imagery (cubes) expressing the seismic reflection coefficient. This coefficient expresses the amount of energy reflected at a sub-surface boundary. The reflection coefficient is proportional to seismic impedance which is in turn related to the velocity of seismic waves through the sub-surface and the density of the sub-surface materials.
Onshore seismic reflection surveys for natural resources usually cover wide geographical areas. These may be dessert lands, transition zones such as swamp and mangrove areas, hills, farmlands, lakes or tidal flats. The GII has experience in all these areas around the globe.
Seismic reflection surveys may also be carried out in High Resolution in smaller areas when the objectives are shallower such as in the Engineering and Homeland Security sectors.
The process begins with survey design. During the design, the GII’s geophysicists and geodetic experts plan together with the client and local representatives the placement and orientation of seismic lines. On each seismic receiver line geophone receivers will be placed at a spacing which influences the final product’s resolution. Furthermore, along seismic source lines the seismic source, be it seismic vibrator vehicles or special seismic explosives, will transmit seismic (sound) waves into the ground.
Once the design is approved, geodetic surveying and permitting with local communities and land owners commences. The surveying team will create very precise geodetic grids using advanced GPS technology and will precisely mark the location of every geophone to be planted. The permitting team will collect consent from every single land owner whose land will be crossed while fulfilling the survey.
After surveying and permitting is completed the geophone layout begins. Depending on which type of recording system is chosen for your project, cabled or nodal geophones, the planting and moving sequence of geophones will vary. In cases where explosives are the chosen seismic source, seismic shot holes will be drilled in parallel with the surveying and geophone planting.
Finally, production starts and the seismic sources transmit the seismic waves into the ground. Daily in-field Quality Control is performed by our expert geophysicists on the data to make sure that the highest data quality is achieved.
Next steps will include Advanced Processing and Interpretation of the seismic data.
Contact us to determine the right design, layout, timeline and crew size for your project’s needs.
Terrain Types
- Farmlands
- Deserts and Dunes
- Mountains
- Forests
- Delicate Natural Habitats
- Urban
- Transition Zones
- Lakes and Shallow Water
Main Technologies
Seismic Sources
- Seismic Vibrator Buggy: INOVA AHV-IV 364 PLS Commander (SPECS)
- Shallow Borehole Explosives
- Accelerated Weight Drop (AWD)
- Drop Hammer
- Sledge Hammer
- Air Guns
Recording Systems
- INOVA G3i SPM 24 bit cabled system
- INOVA Quantum Innoseis Nodal Systems (SPECS)
- INOVA Hawk SN11 Nodal systems
- Geode 24 1C stations (vertical 10Hz, horizontal 8Hz), single S-wave & single P-wave
Ancillary Equipment
- Portable and 4x4 tractor mounted shot-hole drilling rigs
- GPS Systems: Trimble R-10 and R-8 GNNS, Topcon GR-3
- Total station: Topcon 7505
- Garmin handhelds
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