The coalbed groundwaters contain primarily sodium and bicarbonate and are effectively devoid of sulfate, calcium and magnesium. The groundwaters are typically freshwater, with total dissolved solids (TDS) values ranging from 814 to 2657 mg/L. Differences in hydrogeology and structural geology divide the study area into four gas domains. In the northern Hancheng area, the predominant northwest flow of groundwater has resulted in higher gas content in the west (> 12 m3/t) than in the east (8-12 m3/t), even though the coals in the east have high thermal maturity (2.1%-2.3% Ro). The area with the highest gas content (> 16 m3/t) is in the region near the downthrown side of the Xuefeng-Nan Thrust Fault in the northern Hancheng area, and the fault forms a barrier to the northwestward flow of groundwater. The area with the lowest gas content (< 4 m3/t) is in the southwest Heyang area, where there is no entrapment mechanism and the gas has been flushed out of the coals due to a reduction of hydrostatic pressure and active groundwater flow from the east. Structural and hydrodynamic mechanisms, especially the intensity of the hydrodynamic activity and the groundwater flow pathways, are important for gas accumulation in the Weibei field.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址:北京市海淀区学院路29号 邮编:100083 电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700 |