Controlling effects of structural-hydrogeological conditions on coalbedmethane accumulation in Xishan Coalfield

Coalbed methane rich integration were controlled by many factors such as structure, sedimentary environment, hydro-geological conditions, magnetic activity. In order to study the main controlling factors of coalbed methane enrichment and its accumulation law in Xishan Coalfield, this paper collected and sampled the data, and found that the main controlling factors of the coalbed methane in Xishan Coalfield were structure and hydro-geological conditions. The hydro-dynamic and hydro-chemical fields of Taiyuan Formation aquifer and Shanxi Formation aquifer were studied the data of the hydro-logical pore from several Xishan Coalfield.And then the favorable structural, hydrodynamic and hydro-chemical factors for coalbed methane were found out by using the gas content of coalbed methane wells, and three structural-hydrodynamic reservoir-forming models were proposed. Finally, based on the previous studies, this paper proposed identification criteria of coalbed methane enrichment area under the structure-hydrodynamic control system to identify the enrichment area in the study area. The results show that: ①Xishan coalfield strata hydrodynamic field can be divided into: south-central systemⅠ, northwestern system Ⅱand east system Ⅲ; the hydrodynamic activity was relatively weak in the southern Yuanxiang，Dongqu coal mine,near Duerping fault and in the core of Shuiyuguan syncline, which was conducive to CBM accumulation. ②The water chemistry that was conducive to the enrichment of coalbed methane was sodium bicarbonate; ③Three modes of structure-hydrodynamics which were beneficial to coalbed methane accumulation and accumulation were proposed: monoclinic-hydrodynamic accumulation, syncline-hydrodynamic accumulation, fault-hydrodynamic accumulation.④The coalbed methane enrichment areas in Xishan Coalfield were identified：one was near Xingjiashe and the other was in the south of Duerping. The above method was used to quantify and standardize the control effect of structural-hydrological and geological conditions on coalbed methane accumulation, which was beneficial to reference and utilization of other blocks.