Gravity Map Zeroes in on Likely Oil
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Map shows variations in gravitational force across the surface of the Earth. Knowledge about these small variations is a valuable tool in oil exploration.
A unique new high-resolution map of the Earth’s gravitational force provides a hitherto unseen level of detail, covering both land and sea regions with a resolution of only two kilometers. The map shows small variations in gravitational force across the surface of the Earth — knowledge that is a valuable tool in oil exploration.
Previously, oil companies identified interesting areas in the first phases of exploration using protracted, expensive measurements from planes or ships. However, since subterranean oil deposits are encapsulated in relatively light materials, such as limestone and clay, they have less gravitational force than the surrounding materials. This means that areas of interest appear clearly on the gravitational map, and oil exploration can be planned much more efficiently.
Ole Baltazar, senior scientist at DTU Space, headed the development of the map, which he says will be particularly useful as the ice melts in the oil-rich Arctic regions: “The map will also be worth its weight in gold when the ice in the Arctic seriously begins to melt, revealing large sea regions where it is suspected that there are large deposits of oil underground. With our map, the companies can more quickly start to drill for oil in the right places without first having to go through a resource-intensive exploration process.”
The success of the new map is due in large part to the fact that it is not based on direct gravitation measurements but on observations of the height of the sea, which reflects the gravitation.
“Height measurements have the advantage that it is possible to determine the gravitational field very locally and, thus, make a gravitational map with a resolution of a few kilometers. For comparison, the resolution of satellite measurements of gravitational force is typically around 200 kilometers. Satellite gravitation measurements are used, for example, to explore conditions in the deeper strata of the Earth, but are not well suited to our purposes,” explains Baltazar.
The U.S. company Fugro has already made use of the gravitational map, initiating a research partnership with DTU Space.
“Ole Baltazar’s gravitational map is the most precise and has the widest coverage to date,” says Li Xiong, Vice President and Head Geophysicist with Fugro. “On account of its high resolution and accuracy, the map is particularly useful in coastal areas, where the majority of the oil is located.”