Borehole surveys
Geophysical borehole surveys as a full service from field acquisition to data processing & interpretation or to the extent required by the customer.
Borehole survey provides useful information
Borehole geophysics provide accurate information about the drill hole wall and the area around the hole. GRM offers downhole measurements up to a depth of 2500 metres.
Measurements are often taken alongside the drilling project to ensure the hole stays open and to provide immediate information to guide the drilling when conductive and/or magnetic formations can be detected around the hole and below the bottom of the hole, e.g. by TEM measurement of the hole.
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Mapping unpierced leads around the hole i.e. Off-holes
Determining the size and continuity of intersected conductors
3D model of conductors
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Observation of magnetic anomalies around the hole
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IP and RES measurement
Reddish mineralisation (reserve anomaly)
Determination of specific resistance differences
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Mineralization intersected with at least one hole
Determining the continuity between holes
Determining the continuity over wider area with combined ground measurements
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Actual XYZ location of the hole from the beginning to the end of the hole
During or after drilling through pipes in an open hole
Hole logs produce a directional image of the borehole wall, a "virtual scan", which can be used to accurately determine the orientation and dip of different geological units, both in individual fissures and in interesting mineralisation.
Hole pattern services include:
- Optical imaging
- Acoustic imaging
In-situ physical measurement
In-situ physical measurements are used to determine the physical properties of the bedrock through which the hole has been drilled.
The results provide a better understanding of the geophysical responses caused by different rocks and allow the geophysical properties of each geological feature to be recorded. This will allow the selection of the most appropriate methods for further investigations at the site and the performance of more accurate 3D modelling of the existing geophysical data.
Parameters to be defined by in-situ measurement services:
- Susceptibility
- Normal resistivity & Focused resistivity
- Chargeability (IP effect)
- Inductive conductivity
- Density (gamma-gamma)
- Natural gamma radiation
- P- and S-wave speed
