Classification of Sand dunes Using JERS-1 Data for Petroleum
Exploration in the Eastern Junggar Basin, People's Republic of China
Discussion and Conclusions
It is indicated in Figure 3 that Unit 1L dominates in the southeastern and northwestern parts of the study area, while Units 3M, 3H and 4H are dominant in the central, northeastern and southwestern parts of the study area. This indicates that it would be easier to conduct a seismic operation in the southeastern and northwestern parts of the study area because the dune's wavelength is mainly long and their energy if low. It is predicated that in the areas covered by Units 3M, 3H and 4H, operation would be less efficient and the survey design and equipment would require changes.
Considering that the slope of the dune is one of the most important parameters as well as the classified units mentioned above, when planning transportation and operation, the ratio of Wavelength and Relief Energy was defined as Slope Index. This new index simply means that the smaller and the Slope Index, the gentler the slope and vice versa. For determination of Slope Index of each sand dune unit, the following expedient figures were adopted on the categories of Wavelength and Relief Energy, respectively.
| Wave-length (m) |
1 |
2 |
3 |
4 |
| 350 |
250 |
150 |
50 |
| Relief Energy (m) |
L |
M |
H |
| 10 |
15 |
20 |
In order to create a base map, both an appropriate seismic source (vibrator or dynamic and the associated efficiency of operation were considered and plotted on the basis of the Slope Index. Practical considerations for selecting a seismic source is that, track-mounted vibrator is an efficient tool for flattened or very gentle slopping areas, while dynamite can be used all-around regardless of topography, but normally requires drilling operation which inevitably limits the daily production of shooting.
Based on the above discussion, the entire area of the study was classified into four zones as below and was mapped in Figure 4.
Figure 4. Classification Map of Sand for Seismic Survey Planning.
Va : Vibrator easily workable in the N-S direction (Slope Index = 0.03)
Vb : Vibrator workable in the N-S direction (Slope Index = 0.04)
Da : Dynamite source required, Zone of gentle and low relief energy
(Slope Index = 0.06-0.08)
Db : Dynamite source required, Zone of steep slope and high relief energy.
(Slope Index >0.10)
It is evident in Figure 4 that N-S lines between the dunes, would be much easier to shoot than E-W lines, as the former crosses fewer dunes than the latter. Furthermore, this base map provide information when deciding the location, direction and length of the lines, seismic source and ways to detour dunes for logistics.
Based upon the above satellite image interpretation as well as a field verification survey, the results conclude that remote sensing technology can provide a variety of information for seismic planning. Any knowledge obtained will make a great technical and economic impact on hydrocarbon resources exploration in untrodden areas.
Acknowledgments
The authors are grateful to Mr. Toru KAWAKAMI, General manager of the Department of Research and Development of the Earth Remote Sensing Data Analysis Center, for permission to present this paper. They also are much indebted to Mr. Li Da Zeng, Senior Engineer of the Geological Exploration Department of the Xinjiang Petroleum Administrative Bureau, who kindly provided technical support during the field verification survey, and Mr. Koji HAYASHI, General Manager of the Exploration Department of Japan Energy Development Co., Ltd., for critical reading of the manuscript.
References
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Carroll, A. R., Brassell, S. C. and Graham, S. A. (1992) : Upper Permian lacustrine oil shales, southern Junggar basin, northwest China, AAPG Bull. vol. 76, no. 12, p. 1874-1902.
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ERSDAC (1996) : JERS-1 data application for resources exploration in the eastern Junggar basin, People's Republic of China. in Report on search and development of remote sensing technology for non-renewable resources (in Japanese with English abstract).
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Mackeee, E. D. (1979) : Introduction to a study of global and seas. In McKee, E. D. ed, A study of global sand seas, U. S. Geol. Survey Prof. Paper, 1052, p. 1-21.
