Techniques
Seismic Tomography
Borehole Seismic Tomography
Creating a subsurface velocity image
Borehole Seismic Tomography is used to derive an image of seismic velocity between two or more boreholes by measuring travel time between source and receivers along various ray paths. The technique is used for detailed and targeted evaluation of a material.
The result
A velocity tomogram
Overlapping ray paths are used in computations to create a velocity image, also known as a tomogram. The tomogram helps identify anomalous zones that are visible as velocity contrasts.
One hole is used as source hole, and for wave generated at various depths in this hole, travel times are measures at number of receivers in the other hole, also known as receiver hole. This yields a network of overlapping ray paths, which are used in computations to create a velocity image, also known as tomogram. The tomogram helps identifying anomalous zones that are visible as velocity contrasts.
Applications
Typical applications are:
- Determination of material properties
- Identification of features like fault zones and voids
- Mapping of loose zones, sinkholes, anomalous zones in structures like dams
- Study of old foundations
The application areas of seismic tomography are
High-resolution targeted investigations
Experts with PARSAN have been involved in high resolution seismic tomography for various projects in the country, and have used it for number of new application areas.
