Construction of index system of “Hierarchical progressive” geological selection of coalbed methane in multiple seam area of eastern Yunnan and western Guizhou

In terms of the geological characteristics of multiple coal seams,high crustal stress and complex tectonic in eastern Yunnan and western Guizhou,the concept of favorable area,dessert area and vertical dessert in the process of coalbed methane(CBM) geological selection was put forward,and the relationship of “ Hierarchical progressive” be- tween the three was clarified. The favorable area refers to the favorable syncline in a number of secondary syncline. The dessert area refers to the “target area” for the development of CBM from favorable syncline. The vertical dessert is a vertical optimization of the combination layer in the “target area” of CBM development. The key indexes of CBM geo- logical resources,geological resources abundance and recoverable resources were put forward in the optimization index system of favorable area aimed at the characteristics of a large of secondary syncline,great difference in many parameters and exploration degree. The amount of CBM geological resources and the abundance of CBM geological resources are one vote veto. The key indexes of fault fractal dimension,tectonic curvature and buried depth were proposed in the optimization index system of the dessert area aimed at the characteristics of complex tectonic and high crustal stress in the study area. The fractal dimension value of the fault is one vote veto. The key indexes of coal structure,critical de- sorption pressure difference and reservoir pressure gradient difference were put forward in the optimization index sys- tem of the vertical dessert aimed at the characteristics of the development of multiple coal seams and the interlayer in- terference in the study area. The coal structure is one vote veto. In all stages,the corresponding reference indexes were put forward. Finally,the index system of CBM geological selection for the characteristics of the study area was con- structed.