Terravision Exploration Ltd can present GPRplus™ data in three different ways:
1. Permittivity Profiling
Permittivity profiles are low resolution and often used for understanding larger geological structures in unexplored areas such as in space exploration.
A permittivity profile shows the distribution of relative dielectric permittivity (RDP) in the subsurface.
2. Reflection Profiling
A reflection profile is the most common method of displaying GPR data and is often used to provide greater resolution of the subsurface. A reflection profiles displays the reflections generated at the interface between materials of contrasting dielectric permittivity. The higher the contrast, the stronger the reflection.
3. Time-slices from 3D Interpolation
A time-slice is the interpolation of several vertical GPR profiles to produce an amplitude map for a given time value. The depth of the time-slice is then calculated by accounting for the velocity of the signal.
Terravision Exploration Ltd is able to apply a series of filters to GPRplus™ data to best highlight features of interest or suppress unwanted reflections. This post-processing is an incredibly important step that precedes comprehensive data analysis.
Terravision Exploration can create the best post-processing flow to get the most out of your data and help turn the non-intuitive, intuitive.
Data is collected by the operator and downloaded into a laptop for analysis on proprietary software. It takes roughly one day to fully analyse one kilometre of data. Ongoing analysis will take place after data collection each day, where a good understanding of the results will be possible. The final report will be delivered no later than 21 days following the completion of data collection.
Data processing of the radargram is made in such a way that the algorithmic filters are selected that highlight the lithological (horizontal and vertical boundaries), as well as the structural heterogeneity of the profile. When selecting a setting we are guided by the known geological data to calibrate geophysical boundaries, according to the geological horizons and irregularities. At every point on the profile, we are able to review the geo-electric properties of the material. This enables Terravision to confidently track the different geo-electrical layers through the whole profile.
On completion of data collection, a written report will be completed within an agreed timeline. Terravision Exploration will adapt the report format to best suit the client’s requirements.
As standard, the written report will contain:
Analysed geophysical data
Relevant geo referencing
Summary & recommendations
RATE OF COLLECTION
We assume that by “manual” data collection, we will generate between 2.5km to 3.5km of line kilometres per day on land. A video example can be seen at
(a) http://youtu.be/JXEiahFUAww and
This is an arbitrary calculation, and when surveying for smaller targets, it may be necessary to have a much greater “shot concentration” – i.e. more shots over shorter distances, so that several shots pass through each void. Factors such as definition and detail required, size of target features, and antenna/transmitter arrays all define the speed.
As mentioned above, Terravison sees features in real time, and can instantly download data to obtain an initial analysis. Real time analysis can determine whether the target area is interesting and allow “marking” by a DGPS operator.
Preliminary analysis on a laptop can be conducted immediately – on site - to confirm whether the objectives are being met in more detail.