Conventional gravimeters are extremely sensitive weighing devices routinely capable of distinguishing anomalies less than 1 part in 107 of the Earth's ambient field, and gradiometers, which measure the first derivative of the gravitational field, to about 1 part in 3000. Observations of the Earth's gravity field are made with a variety of instruments from different types of platforms, each with its own characteristic measurement accuracy, spatial resolution, and cost of acquisition. Applications of gravity within the oil industry are just as varied, impacting all phases of the business from global tectonic studies to frontier exploration to prospect selection to seismic processing to well logging to reservoir monitoring to site hazard and engineering studies to environmental analysis. Advances inthree technologies, satellite altimetry, Global Positioning System (GPS), and gravity gradiometry, have dramatically improved our ability to acquire higher resolution gravity data. This, in turn, has increased the impact that analysis of gravity data has on exploration applications.
In southeast Asia, inexpensive satellite gravity predicts previously undiscovered minibasins for the frontier exploration group, allowing it to relocate its seismic lines to the more prospective areas.
In the deep-water Gulf of Mexico, drilling operations are suspended while Eddy Whopper, a large vortex of swirling water shed from the Loop Current, passes the drill ship. The drillers, warned by predictions from the ocean circulation model constrained by satellite gravity determinations of the local geoid, are