Abstract:

Based on field investigation and data of borehole pumping test, the structure, hydrogeology and their controls to the
coalbed methane (CBM) preservation in eastern margin of the Ordos basin were discussed. Results showed that the compression
faults and folds with nearly south-north direction develop well in the basin margins, and the tectonic deformation weaken
gradually towards the center of the basin, which indicates the structure both in the margin and center of the basin is all conducive
to the CBM preservation. Five hydrological units in the area were distinguished based on the geomorphological and geological
conditions such as the structure and groundwater recharge and discharge. Hydrodynamic in southwestern Hancheng unit is
stronger than that in other units in the eastern, and that in the Liulin unit is strongest among the eastern units. Superposition of
the hydrodynamic variation on the tectonic setting makes the differentiation of CBM preservation conditions. CBM content in
middle Yellow River depression increases with the increase of the burial depth. Hydrodynamic favorable to CBM preservation in
northern Liulin unit occurs at the western part of the Liulin Spring in the unit. Groundwater dynamic at the northern part of the
Longmenshan unit may be favorable to CBM preservation. Good CBM preservation occurs in the northwest part of the Hancheng
unit due to the stagnant groundwater.