磁共振探测估算含水层渗透系数的原位试验研究

通过一个完整的磁共振探测（MRS）、钻探、抽水试验过程，开展了MRS估算含水层渗透系数的原位试验研究。在分析MRS估算渗透系数准确性的基础上，系统剖析了引起准确性差异的主要因素，并对进一步提高估算效果提出了建议。结果显示：（1）采用现阶段常用的参数设置，与抽水试验计算值相比，MRS估算渗透系数的差值为抽水试验计算值的17.59%。（2）MRS推断的含水层顶板、底板埋深与钻孔揭示的信息相比，差值分别为4.11m、1.03m，表明其对估算渗透系数准确性的影响较小。（3）CP值是影响估算准确性的重要因素，其值为10-9数量级符合大多数地层的特点。另外，通过在已知渗透系数的钻孔附近进行MRS，从而获取CP参考值，应用该值估算的渗透系数准确性高于常用的参数设置。（4）指数a、b设置方面，应用Seevers公式（a=1、b=2）的估算效果优于Kenyon公式（a=4、b=2）。本成果有助于提高MRS估算渗透系数方法在野外条件下的适用性。

In-situ test of magnetic resonance sounding (MRS) in estimating aquifer hydraulic conductivity

In this paper, we carried out an in-situ test of magnetic resonance sounding (MRS) for the estimation of hydraulic conductivity; specifically, this in-situ test was composed of the MRS, drilling and pumping tests. The accuracy of hydraulic conductivity estimation by MRS was analyzed. The influencing factors on the estimation accuracy of MRS was discussed, and some suggestions were put forward to improve the estimation effect. Results were simply described as following: (1) The error of hydraulic conductivity estimated by MRS was 17.59% when the parameter settings took the common parameter settings. (2) The errors of aquifer roof and bottom plate location estimated by MRS were 4.11m and 1.03m, respectively, indicating that the in-situ test provided minor influence on the estimation of hydraulic conductivity. In particular, CP, which was obtained from MRS detection in the vicinity of boreholes (with known hydraulic conductivity), was empolyed to estimate hydraulic conductivity, resulting in higher accuracy than that estimated with common parameter settings. (3) The value of CP was an important influencing factors which generally was assigned to a magnitude of 10-9 fit with the characteristics of most aquifer. (4) The Seevers formula (a=1, b=2) is more applicable than the Kenyon formula (a=4, b=2). These results can be used to improve the applicability of MRS method in estimating aquifer hydraulic conductivityin the field