Study On Gas Movement Law And Risk Control Of Tunnel Construction In Oil And Gas Fields

With the continuous expansion of the railway network,the number of tunnels constructed through oil and gas formations has gradually increased,and is mainly concentrated in mountainous areas in central and western China.The gas problem has gradually become a key issue in the construction of tunnels in the region.Although many scholars have done a lot of research on gas tunnels at present,the researches mostly focus on the layered tunnels of coal measures,and the research on gas tunnels in oil and gas fields is still shallow.In addition,the gas occurrence in oil and gas field areas is very different from coal-bearing strata.For example,the gas occurrence in oil and gas field areas has a high degree of uncertainty and is greatly affected by adverse geological structures such as source-cut faults and joint zones.,Greatly increasing the risk of construction.Therefore,in this paper,taking the high gas tunnel in the oil and gas field area—Longquanshan Tunnel as the engineering background,the method of combining regional geological analysis and theoretical analysis with numerical simulation is used to analyze the gas occurrence in the tunnel site,the tunnel construction to the surrounding rock mechanical field,and the gas Analysis of the migration law,combined with the actual working conditions,research on the gas management plan,and achieved the following results:(1)Based on the study of the geological structure history of Longquan Mountain area,and combined with the site survey results,the main sources of gas in the surrounding rock of the tunnel site,reservoir space,and trap structure are analyzed,and the influence of gas occurrence is studied.(2)A numerical model is established for tunnel construction simulation.Under the condition that the stress field of the surrounding rock is disturbed,the change law and influence range of the mechanical field of the surrounding rock,the development of the plastic zone in the surrounding rock,and its changing rule are analyzed.The changes of the gas pressure field in the surrounding rock are analyzed,and the simulation results and the actual monitoring data are analyzed and checked to obtain the gas migration law in the surrounding rock under the disturbance condition.(3)Based on the gas management plan of Longquanshan Tunnel,the tunnel ventilation plan is studied.Affected by differences in gas occurrence,a single treatment solution cannot effectively solve the gas problem.A comprehensive treatment plan combining grouting,gas drainage and construction ventilation in the tunnel site was proposed to guide on-site risk control and achieve efficient gas treatment.The purpose of the question.