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Formation Mode of Shallow Natural Gas in the Laoshishan Tunnel on the Kunming-Nanning Passenger Dedicated Line
(1 China Railway Eryuan Engineering Group Co. Ltd., Chengdu 610031;
2 School of Resources and Environment, Southwest Petroleum University, Chengdu 610500)
Abstract Focused on the emission and burning of natural gas in the Laoshishan tunnel on the Kunming-Nanning passenger dedicated line, which passes through a non-coal stratum, the formation mode of natural gas was researched regarding the causes of tunnel hazards and natural gas sources. Based on the geological conditions of the emission area, the characteristics of the oil-gas generation layer, the reservoir layer, and the bearing layer were analyzed, proving that: 1) the anticline structure at the tunnel's exit is the affected area for oil and gas migration; 2) a series of underlying generation layers have the capacity to generate oil and gas; and 3) the shallow accumulation of oil and gas is possible via the fault structure. According to a comparison of gas concentrations before and after tunnel excavation, it is determined that shallow natural gas mainly comes from deep rock below the tunnel floor, and the rock around the tunnel body may have already been affected by accumulation at individual sections. The causes of shallow natural gas in the Laoshishan tunnel are obtained by analyzing gas distribution characteristics and the gas formation mode: namely, the gas comes from the shale of the Qiongzhusi formations of the deep Silurian system and the Cambrian system with migration along the Longquansi fault zone.
Abstract：
Focused on the emission and burning of natural gas in the Laoshishan tunnel on the Kunming-Nanning passenger dedicated line, which passes through a non-coal stratum, the formation mode of natural gas was researched regarding the causes of tunnel hazards and natural gas sources. Based on the geological conditions of the emission area, the characteristics of the oil-gas generation layer, the reservoir layer, and the bearing layer were analyzed, proving that: 1) the anticline structure at the tunnel's exit is the affected area for oil and gas migration; 2) a series of underlying generation layers have the capacity to generate oil and gas; and 3) the shallow accumulation of oil and gas is possible via the fault structure. According to a comparison of gas concentrations before and after tunnel excavation, it is determined that shallow natural gas mainly comes from deep rock below the tunnel floor, and the rock around the tunnel body may have already been affected by accumulation at individual sections. The causes of shallow natural gas in the Laoshishan tunnel are obtained by analyzing gas distribution characteristics and the gas formation mode: namely, the gas comes from the shale of the Qiongzhusi formations of the deep Silurian system and the Cambrian system with migration along the Longquansi fault zone.
WANG Guang-Neng-1,
SU Pei-Dong-2,
DU Yu-Ben-1 etc
.Formation Mode of Shallow Natural Gas in the Laoshishan Tunnel on the Kunming-Nanning Passenger Dedicated Line[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(6): 7-11
2014, Vol. 51 