A new way to look at the Earth began with the launch of the first satellite in 1957. Today more than 2,200 satellites orbit the Earth, many providing a steady stream of scientific data. Accurate satellite imagery may be the most cost-effective source of data collection in oil and gas exploration. And it often has the ability to reach parts of the Earth that are otherwise too difficult to access.
The most common and valuable types of satellite data used in the energy industry include multi-spectral, hyperspectral, gravity, magnetic and remote sensing (the use of aerial photography [often satellites], combined with other methods to view that which cannot be seen by the unaided eye).
NEOS geoscientists generate valuable interpretive products using satellite or public data, including:
- Assessments of basin-scale geologic trends
- Maps of basin architecture and regional structure
- Maps of key lineaments, regional fault systems, and intrusions
- 2-D and 3-D structural and stratigraphic models
- Maps of basement topography, faulting and composition
- Assessments of relative acreage prospectivity derived using predictive analytics.
In this blog series, we look closely at the data provided by satellites that reside in the public domain, to see what value can be gleaned, as well as encountered limitations that result from partial spatial samples or true global coverage.
The above images are provided by University of Texas Center for Space Research and NASA.
What is it: The GRACE (Gravity Recovery And Climate Experiment) mission is dedicated to making detailed measurements of the Earth’s gravity field anomalies. Its twin satellites fly about 220 kilometers apart in a polar orbit 500 kilometers above Earth. They map the Earth’s gravity field by making accurate measurements of the distance between the two satellites, using GPS and a microwave ranging system. GRACE is on an extended mission, which is expected to continue through 2015.
The GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) satellite is also used to measure gravity. Orbiting at the lowest altitude of any observation satellite, its instrumentation was a highly sensitive gravity gradiometer, mapping the Earth’s gravity field at unprecedented resolution.
Bouguer gravity anomaly, distinguishing thick from thin crust by more negative and positive values. Image provide by ESA/IRENA.
Value: Gravity data is used to define areas of varying density within the Earth for insights into subsurface structure and composition. Satellite gravity data has improved greatly in the last five years and is ideal for imaging basin and tectonic elements, and regional reconnaissance. The data is available for most parts of the world, including both onshore and offshore environments. Also, since the gravity satellite data is available now, there is no lag time for acquiring new data.
Limitations: Like most satellite data, the limitation of the satellite data is resolution. It cannot detect subtle variations in the subsurface.
Swarm Satellite – Data available via ESA
‘Snapshot’ of the main magnetic field at Earth’s surface as of June 2014 based on Swarm data. Red represents areas where the magnetic field is stronger, while blues show areas where it is weaker. Image provide by ESA.
What is it: As for magnetic data, there have been several satellites since the late 1970s that have collected the Earth’s magnetic field. The most recent is the SWARM mission, which is comprised of three identical satellites. These satellites have new generation instruments to deliver extremely accurate satellite magnetic data. It joins the Orsted and CHAMP satellites, both still in operation.
Value: Magnetic data deduces subsurface lithology and structure, including the presence of ore deposits, intrusive and extrusive bodies, and faults. In hydrocarbon exploration, magnetic techniques help geoscientists infer both total sediment thickness and the thermal maturation history of a basin by imaging the basement structure.
Limitations: Again, the limitations of the magnetic satellite data is resolution. It is ideally used for regional reconnaissance or basin imaging, where preliminary insights can help guide more detailed programs aimed at highgrading acreage or sweet spot mapping.