Structure Control on Gas Deposition in Qidong Minefield of Huaibei Mining Area

Based on gradual control theory of gas deposition structure and regional structure evolution, the paper discussed gas deposition controlled by the struct ure formed under different period and different property structure stress field after coal formation of Qidong Minefield in Huaibei Mining Area.The results showed that Ya nshan period was the key period to control the gas deposition, series faults and folds formed under a role of a NW- SE horizontal extrusion stress field settled the struc ture pattern and gas position features in Huaibei Mining Area.In the structure evolution process after the coal formation, the EW directional structure was in extrusion at the initial period and in tensile at the late period and was favorable for the gas dissipation.A NE- NNE directional structure roughly experienced three evolution process es, including the extrusion shearing-tensile-extrusion and the NW directional structure was always in an extrusion state.The NW directional structure was the most favor able for gas keeping, NE- -NNE directional structure was the second and the EW directional structure was the worst.The different property faults formed in different peri ods in Qidong Minefield changed the gas deposition pattern within the minefield and caused the gas deposition features differentiation in the south and north, and partiti on in the east and west. The gas deposition features and control factors between each fault and block would be different and each fault and block would be an independ ent gas geological unit.