Abstract：In order to study the structural complexity of main coal seam No. 6 in Bide block, Zhina coalfield, Guizhou province, the four parameters of the structural curvature, fault strength, fault density and fault fractal dimension were chosen to construct an evaluation index system for the complexity by using analytic hierarchy process. Combining the fractals theory and the development with distribution of faults and folds in the block, the complexity of the structure of coal seam No. 6 was quantitatively studied and evaluated, and the complexity of reservoir structure was zoned. The results showed that the types of the tectonic complexity in the study area were mainly simple and moderate, and the structural complex areas were mostly concentrated in the fringe of the block where developed faults and large folds; the complexity of the structure was mainly controlled by large folds such as Yanjiao syncline and Agong syncline. The faults exacerbated the complexity of the reservoir to a certain extent which indicated the structures within the block had a significant control over coal seam No. 6.

Keyword：Bide block;coal reservoir;structural complexity;analytical hierarchy process;quantitative assessment;