土壤气抽提多井方案的数值模拟研究

以存在石油烃污染的北京市某加油站场地为研究对象,设计了土壤气抽提(SVE)原位修复系统,应用AIR3D软件对SVE作用下土壤包气带的气压场进行数值模拟.划定以土壤气压强低于或等于101.122kPa的区域为抽气影响区域.模拟结果显示,单井的抽气影响区域不能满足要求;多井抽气时,井间区域土壤气体真空度受多井共同作用,扩大了抽气的影响区域.抽气井不同布置情况下井间距大小对相互作用效果存在影响.研究发现,井间相互作用随着井间距的增大而减小,井间距存在临界值.井间距临界值与抽气井的布置形式相关.对于本研究中的2眼井、3眼井、4眼井情景,此临界值分别在3~5m、5~8m、8~10m区间.超过此临界值时井间相互作用将显著减弱,并导致抽气影响区域不能覆盖整个井间范围.

Simulation of multiple wells system in soil vapor extraction

A numerical simulation of the air pressure distribution in the contaminated vadose zone was conducted using the AIR3D model,based on the designed in-situ SVE remediation system for the contaminated gas-station site.An affected area was defined as the domain which has an air pressure lower than 101.122kPa.At first,a single well was used in the simulation,but the result turned out that the affected area was not sufficient to cover the contaminated zone.Then a multiple wells system was proposed,and the combined and enhanced effect was observed.Further,the influence of well interval and well distribution on the affected area was discussed in the multiple wells system.The numerical results showed that interaction between wells decreases along with the increase of the well interval.There existed a critical value representing the maximum well interval of the combined effect.The critical well interval varied with the change of the well distribution pattern.The critical well intervals in the 2-well,3-well,4-well systems discussed in this study are in intervals of 3-5m,5-8m,8-10m respectively.In well systems with larger well intervals than the critical values,interaction between wells would decrease significantly,and the affected area would not cover the entire inter-well area.