Abstract: In this paper, to optimize the surface borehole network for gas drainage above the abandoned gob, considering the geometric boundary intersection of the gas leading fracture zones as the criterion for the connection of adjacent abandoned gobs, the method and procedures to judge the connection of adjacent abandoned gobs both in longitudinally and horizontally were given, and the region division method of gobs based on the connectivity of abandoned gobs was put forward. Meanwhile, according to the gas sources in abandoned gob, the calculation model of gas reserves in abandoned gob was built by using separate source method. In addition, the pipe network optimal layout problem of the surface borehole for gas drainage from abandoned gob was transferred equally to a graph theory problem solving in the minimum spanning tree of weighted connected graph, and Kruskal method was clearly illustrated to solve the formation of the minimum spanning tree. Finally, the method and procedures were further explained to optimize the surface borehole network arrangement for gas drainage from abandoned gob.

Key words: abandoned gob, gas drainage, surface borehole