基于双Packer抽水试验的洛河组水文地质特征垂向变异性研究

Vertical variability of hydrogeological characteristics of Luohe Formation by double packer system pumping test

  • 摘要: 为了精细探查鄂尔多斯盆地巨厚洛河组水文地质条件并定量评价其含水层段富水性垂向变异特征,提出采用导水系数进行含水层富水性评价,给出了导水系数法富水性7级分级标准;采用双Packer系统对陕西高家堡井田DJ1、DJ2钻孔洛河组垂向10个固定厚度层段进行抽水试验并计算水文地质参数,采用综合富水性指数法对洛河组垂向分层并对比分析其垂向分层水文地质特征。结果显示:(1) 提出导水系数富水性分级标准,即T≤1 m2/d、1 m2/d<T≤10 m2/d、10 m2/d<T≤50 m2/d、50 m2/d<T≤100 m2/d、100 m2/d<T≤200 m2/d、200 m2/d<T≤400 m2/d、T>400 m2/d依次表示富水性极弱、弱、中等、强、很强、特强、极强。(2) 采用综合富水性指数法将洛河组垂向上划分为上段、中上段、中下段和下段4个含水层段。(3) 洛河组垂向分层水文地质特征存在差异。中上段和中下段厚度相对较大,分别为122.20~124.30 m和113.30~148.70 m,岩性以砂岩类地层为主,渗透系数K分别为0.598 9~0.708 5 m/d和0.111 5~0.211 5 m/d,导水系数T分别为65.60~116.94 m2/d和11.05~30.89 m2/d,均相对较大,富水性中等至很强,为主要含水层段;上段和下段厚度相对较小,分别为20.45~35.20 m和57.60~91.19 m,岩性为砂泥岩互层,渗透系数K分别为0.064 6 m/d和0.005 1~0.009 0 m/d,导水系数T分别为1.58 m2/d和0.34~0.66 m2/d,均相对较小,富水性极弱至弱,为次要含水层段。(4)导水系数在多个含水层段之间具有确定的换算关系,采用导水系数法评价显示洛河组含水层段富水性在垂向上存在显著差异,现场应用效果良好。

     

    Abstract: To investigate the hydrogeological conditions of the thick Luohe Formation in Ordos Basin and quantitatively evaluate vertical variation characteristics of its aquifer’ s water-rich, proposes the method of using the coefficient of transmissibility to evaluate the water-rich of the aquifer, and give the seven level classification standard of water-rich by the method of determining coefficient of transmissibility. The double-packer system was used to carry out the pumping tests of 10 vertical sections of fixed thickness of the Luohe Formation in the DJ1 and DJ2 boreholes in the Gaojiabao mine field, shaanxi, and the hydrogeological parameters were calculated. Using the comprehensive water-rich index method to stratify the Luohe Formation vertically and analyze its hydrogeological characteristics vertically. The results show that: (1) The water-rich standards of coefficient of transmissibility are given; when T≤1 m2/d, 1 m2/d<T≤10 m2/d, 10 m2/d<T≤50 m2/d, 50 m2/d<T≤100 m2/d, 100 m2/d<T≤200 m2/d, 200 m2/d<T≤400 m2/d and T>400 m2/d, the water-rich is very weak, weak, medium, strong, very strong, especially strong, and extremely strong. (2) The Luohe Formation is vertically divided into four aquifers including the upper, middle-upper, middle-lower and lower aquifers by the comprehensive water-rich index method. (3) The Luohe Formation vertical hydrogeological characteristics are different. The middle-upper and middle-lower formation are the main aquifers, which are dominated by sandstone strata and relatively thick (122.20-124.30 m and 113.30-148.70 m, respectively), the permeability coefficient K (0.598 9-0.708 5 m/d and 0.111 5-0.211 5 m/d, respectively) and coefficient of transmissibility T (65.60-116.94 m2/d and 11.05-30.89 m2/d, respectively) have relatively large values, and the water-rich are from medium to very strong; The upper and lower formation are the secondary aquifers, which are dominated by sand-mudstone strata and relatively small (20.45-35.20 m and 57.60-91.19 m, respectively), the permeability coefficient K (0.064 6 m/d and 0.005 1-0.009 0 m/d, respectively) and coefficient of transmissibility T (1.58 m2/d and 0.34-0.66 m2/d, respectively) have relatively small values, and the water-rich are from very weak to weak. (4) The coefficient of transmissibility has a definite calculation relationship among multiple aquifers. The coefficient of transmissibility method is used to evaluate the vertical water-rich of the Luohe Formation, and there are significant differences. Therefore, the application was successful.

     

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