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Remote Sensing Research for Geological Area Selection of Coalbed Maehane in Qinshui Basin, Shanxi, Chian

Feng Fucheng, Mao Yaobaom Wan Young, Wang Xinmin
Aerophotogrammetry & Remote Sensing Bureau of Chian Coal
Xi'an, China, 710054

How to improve exploration effect, reduce expolaration cost by applying new technology and synthetic exploration tracts is a important tactics is a important problem in geological area selection of coalbed methane. . Taking Qinshui basin as a case study, which is most potential area of coalbed methane, this paper demonstrates the working procedures, methods and effects of remote sensing research in techonic characteristics of geology, of coal seam, highly permeability and rich coal gas area detection. The Research results have been testified by severzl drilling holes of coalbed methane.

Qinshui Basin is located in middle southern Shanxi province, China. It belongs to Carboniferous and Permian period coal field of middle northern china. Affected by Yanshang movement, the basin is a large. Synchinorium in Northeast direction. The prospective reserve of coalseam is about three hundred billion tons.

Processing from geological characteristics research of coalbed methane and deposition regularity research, coal gas bearing characteristics and permeability characteristics which affect business exploarations are analyzed and predicted by remote sensing technology.

The advantage of coalbed methane exploaration in Qinshui Basin is hig coal gas content and saturation degree of coal gas, which was controlled by tectonic characteristics and coal bearing characteristics of the basin. The disadvantage is that the coalseam cleats are not developed. The permeability is relative low due to the high metamorphic degree of coal (most coal in the basin are anthracites). So the key works in geological area selection of coalbed methane is to seek for the area where the tectonic fracture are developed and the tectonic fracture are developed and the coal seam have additional permeability.

It is difficult for traditional methods to look for such area. On the contrary, the remote sensing technology can solve the problem due to its advantage in researching tectonic characteristics.

Taking SPOT satellite imagery and TM imagery as basic information source. Using several techniques such as digital imagery processing and computer information extraction, tectonic control analysis of coal gas, linear structure and fractal analysis, tectonic bent analysis of coal seam, paleo and modern earth stress analysis. The developed fracture areas of coal seam are predicted and higher permeability areas are selected.

The principles of remote sensing detector
Premeability of coal seam is related to coal seam fracture, coal seam fractures, coal seam fractures can improve permeability of coal seam. According to our research, joint system of land surface are similar in trend, location and spatial arrangement when underground coal seam and strata of land Surface belong to one set of strata combination and they are controlled by same paleo tectonic background. Therefore joint system of land surface can be detected by remote sensing interpretation and statistical analysis of linear features.

The methods of remote sensing detection
  • Tectonic stability assessment can define the area where coalbed methane is preserved in good condition.
  • Predicting fracture developed area of coal seam in tectonic stability areas
  • Digital imagery enhancement processing This process can obtain optimum imagery for liner feature interpretation.
  • Linear feature interpretation Linear feature display as linear scarps, linear drainage, linear erosion features, aligned geomorphic linear and significant geomorphic trend.
  • Statistical analysis of linear feature To define the preponderant direction, the direction can represent possible trend regional fractures.
  • Statistical analysis and fractal geometry analysis of linear features In tectonic - geomorphological assessments units distribution intensity of linear features was calculated by statistical analysis and classified in different level by taking use of fractal geometry value is, the more intensive the linear feature distribution is, the more developed the fracture of coal seam is.
  • To understand open or close state of coal seam fractures by modern earth stress analysis.
  • Selecting favourable area of high permeability by analogy analysis.
  • To predict developed area of tectoclases in coal seam by structure bent degree analysis.
  • Surface strata joints survey and underground coal seam fracture survey.
Geological Area Selection
  • The criteria of area selecting
  • High Gas Content The thickness of coal seam is thicker than 6m, burying degree of coal seam in depth is depth is proper.
  • Additional permeability is produced by tectonic fractures. Favourable area can be defined by fractal geometric value.

    The fractal geometric value are more than 1.7 in favourable areas, and is between 1.6-1.7 in relatively favourable areas.
  • Main fractures in coal Seam should be in opening state
  • Area Selection Results Using Remote sensing technology, 6 tectonic stable areas in basin were delineated, 11 favourable areas of coalbed methane for exploration are selected in 22 assessment units in the tectonic stable areas. They are mainly Located in Jincheng mining area, Yangquan mining area, Xishan mining area, Anze-Qinyuan area.
Suggesstion and Recommendation
  • Strengthening the relationship research of land surface strata joints and underground coal seam fracture.
  • To set up effective and scientific method for area selecting by combing remote sensing, earth physical exploration and drilling.