低渗透性裂隙介质中激发强度对Slug试验的影响研究

Studies on Effect of the Excitation Intensity on Slug Test Results in Low Permeability Fractured Media

Slug试验是一种经济、快速测定介质渗透系数的原位试验方法。但对于低渗透性裂隙介质中不同激发强度对Slug试验影响的报道较少。通过在低渗透性裂隙介质中对同一试验段采用“小—中—大”激发方式开展Slug试验,利用前人建立的Bouwer&Rice理论模型求取低渗透性裂隙介质的渗透系数,对比分析在不同激发强度条件下低渗透性裂隙介质渗透系数计算结果的差异性,并通过求取雷诺数来表征不同激发强度下钻孔附近的实际地下水流态,讨论了适宜的激发强度。试验结果表明:随着激发强度的增加,地下水非线性流作用显著,受非线性流的影响,采用常规Slug试验理论模型求取的地层渗透系数估计值偏低,故在低渗透性裂隙介质中开展Slug试验时,应采用较小的激发强度。

Slug test is an economical and rapid method for determining the hydraulic conductivity in situ.However,little attention has been paid on the effect of excitation intensity on the Slug test in the permeability fractured media.Adopting the“small-medium-large”stimulation method of Slug test for the same test section in the low permeability fractured media,and the theoretical model of Bouwer&Rice established by the previous researchers to derive the hydraulic conductivity of low permeability fractured media,this paper compares the hydraulic conductivity calculation results,calculates the Reynolds number to characterize the groundwater flow pattern near the boreholes,and discusses the appropriate hydraulic conductivity.The results show that with the increase of excitation intensity,the nonlinear flow of groundwater is enhanced,and the hydraulic conductivity of the stratum obtained from the conventional Slug test theoretical model is estimated to be low.In conducting the Slug test in a permeability fractured media,a small excitation intensity should be used.