气压式振荡试验确定地层渗透系数适宜性

Applicability of the hydraulic conductivity determination of formation by pneumatic slug tests

为评价滨海地区海(咸)水入侵区不同类型地层渗透性,提出振荡试验适宜模型选择方法。利用Geoprobe系统对不同平面位置地层实施了气压式振荡试验,部分点位进行了分层测试;利用配线法计算地层渗透系数。结果表明:当试验目标层为承压含水层时,利用Butler模型分析欠阻尼振荡试验,KGS模型分析过阻尼振荡试验,均可获得良好的计算结果;当试验目标层为弱透水层时,KGS模型可用于过阻尼振荡试验的数据分析,但计算结果会受到相邻高渗透性含水层以及钻孔编录不准确的影响。地层渗透性等级未知条件下,需根据地层类型、介质岩性、测试井结构和水位恢复过程曲线特征选择适宜的振荡试验分析模型,以准确获取地层渗透系数值。

To evaluate the permeability of a coastal formation in a seawater（ saltwater） intrusion area and to introduce a method to select applicable slug test models,pneumatic slug tests were implemented using a Geoprobe system at different plane positions. Layered slug tests were also performed at several test sites. The matching-type curves method was used to calculate the hydraulic conductivity parameters of formation. The results show that,if the test target formation is a confined aquifer,good results are obtained from the calculations by analyzing either the overdamped oscillation slug tests using the KGS model or the underdamped oscillation slug tests using the Butler model. If the test target formation is an aquitard,the KGS model can be used to analyze the overdamped oscillation slug tests. The calculation results will be affected by the presence of an adjacent aquifer with high hydraulic conductivity and also by the inaccuracy associated with borehole logging. If the conditions of formation have unknown permeability grade,a reasonable slug test solution model must be chosen to calculate the hydraulic conductivity parameters precisely by analyzing concurrently the layer type,the formation type,the test well structure,and the characteristics of the water level recovery.