花管与潜水面相交下的冲击试验模型研究

STUDY OF MODEL OF SLUG TESTS PERFORMED IN WELLS WHEN WELLS SCREENED ACROSS WATER TABLE

针对潜水井中的冲击试验,在花管与潜水面相交的情况下,由于注入井中的水分潜水面上、下两个部分流入含水层中,造成模型由线性变成非线性的问题,建立新的潜水井中的冲击试验计算模型,给出模型的解析解,并运用溶质浓度示踪技术,算出从潜水面以下部分流走的的水量,最终得到含水层渗透系数。而这与传统研究中,仅通过对测井的有效半径进行修正,来解决这一问题的方法不同。以西藏江雄水库库区一潜水完整井为例,进行现场试验,运用建立的模型,计算出含水层的渗透系数,并将其与Bouwer-Rice潜水井冲击试验模型的计算结果、以及抽水试验的结果进行对比,试验结果表明,建立的模型能够真实地反映地层的渗透特性。对冲击试验标准水头恢复曲线特征进行分析得出:当曲线以较慢速率下降时,才真正反映含水层的渗透特性。

For the slug tests performed in wells screened across the water table in phreatic aquifer,the water injects into the wells through the upper and lower parts of the water table. By calculating the amount of the water flowed away from the lower part of the water table using the technique of tracer test with the concentration of solute,a new model of slug test in phreatic aquifer is built up;and the analytical solution of the new model is given. It′s different from the traditional ways to solve this problem,which usually do it by changing some coefficients to correct the radius of the wells. To demonstrate the correctness of this theory,a series of slug tests are conducfed in a fully penetrating well in the Jiangxiong Reservoir in Tibet. And then the hydraulic conductivity of the formation is calculated using the method. By comparing the result of this value to the calculating results of Bouwer-Rice slug,the results show that the proposed model can truly reflect the permeability characteristics of the formation. By analyzing the standard recovery curve of the slug test,it shows that curve can truly reflect the permeability characteristics of the aquifer when the curve decreases in a slower rate.