Gravity Surveys

AGL Delivers

Aurora Geosciences offers both reconnaissance and seismic line profile gravity surveys to the petroleum exploration industry.

Our particular expertise is in conducting helicopter gravity surveys using carrier phase GPS receivers to obtain elevation control.  Most of our work is at high latitudes where careful pre-survey planning is required to ensure optimum survey production.

• Accurate & precise leveling. Elevation control to within + 5 cm over long base lines is maintained with carrier phase GPS receivers operating in Fast Static or Kinematic mode.  Conventional leveling with total station instruments can be performed on smaller grids or along 2D lines.
• Accurate data. We use Scintrex Autograv CG-3 and CG-3M gravimeters. These instruments have automatic tilt compensation and excellent instrument drift compensation.  Residual drift can be kept to less than 20 microGal per hour even under -40C conditions and operators can quickly identify tares in the field from check-in drifts.
• Precise near-station terrain corrections. Using reflector-less laser range finders, crews can quickly and accurately measure terrain elevations surrounding the gravity station.  The greater volume of terrain data collected in this manner permits a more accurate determination of the near-station terrain effect than can be achieved with conventional clinometer surveys.
• DTM far-station terrain corrections. We extract digital terrain models from available topographic maps and the global digital terrain models (GLOBE 5.0) and use these to compute far station terrain corrections to 100 km. Areas within 5 km of the gravity stations are commonly gridded with a 200 m cell size and more distant areas are gridded with a 1000 m cell size. These corrections can be important when surveying in mountainous areas where terrain strongly influences the apparent Bouguer anomaly vertical gradient.