Difference between revisions of "Magnetotellurics case history: frontier basin analysis (Amazon Basin, Colombia)"
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==Survey results== | ==Survey results== | ||
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The MT data clearly delineated a thick sedimentary section with internal units that could be correlated from site to site. Three resistivity “packages” were observed: | The MT data clearly delineated a thick sedimentary section with internal units that could be correlated from site to site. Three resistivity “packages” were observed: | ||
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* >1000 ohm-m (crystalline basement) | * >1000 ohm-m (crystalline basement) | ||
| − | + | [[:file:applying-magnetotellurics_fig16-5.png|Figure 1]] shows a simulated cross section in the Amazon basin based on MT data. | |
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==Post-MT program== | ==Post-MT program== | ||
Revision as of 15:41, 21 January 2014
| Exploring for Oil and Gas Traps | |
| |
| Series | Treatise in Petroleum Geology |
|---|---|
| Part | Predicting the occurrence of oil and gas traps |
| Chapter | Applying magnetotellurics |
| Author | Arnie Ostrander |
| Link | Web page |
| Store | AAPG Store |
A regional exploration program to study a large unexplored area in the Colombian Amazon basin was conducted by Amoco Production Company in 1987 and 1988.[1] This study area was very large [approximately 300,000 km2 (115,000 mi2)] and remote with dense jungle cover, rugged terrain, and limited road access.
The first phase of the program consisted of 31,700 km (19,700 mi) of airborne gravity and magnetics. The large-scale structures delineated in these surveys were then further investigated by MT The MT survey was feasible with a light helicopter because the crew was small and equipment was light and compact. Data were collected from 43 sites, with a typical spacing of 10–20 km (6–12 mi).
Survey results[edit]
The MT data clearly delineated a thick sedimentary section with internal units that could be correlated from site to site. Three resistivity “packages” were observed:
- 40–100 ohm-m (sedimentary)
- 150–250 ohm-m (sedimentary)
- >1000 ohm-m (crystalline basement)
Figure 1 shows a simulated cross section in the Amazon basin based on MT data.
Post-MT program[edit]
Encouraged by the evidence from the MT survey, Amoco decided to shoot a small seismic program and drill a shallow stratigraphic test. This program was positioned on the edge of a subbasin defined in the MT data. There generally was good agreement between the MT data, the seismic data, and the borehole geology.
The airborne gravity and magnetic data, followed by the surface MT survey, provided a very cost-effective means of regional basin definition and led directly to a well-positioned seismic survey and well site.
See also[edit]
- What is magnetotellurics?
- What does an MT survey measure?
- How are MT data acquired?
- Case history: rugged carbonate terrain (Highlands of Papua New Guinea)
- Case history: Precambrian overthrust (Northwestern Colorado)
- Case history: volcanic terrain (Columbia River Plateau)
References[edit]
External links[edit]
| find literature about Magnetotellurics case history: frontier basin analysis (Amazon Basin, Colombia) |
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