潮汐水位振幅和位相变化研究及其在地下水异常分析中的应用

将多孔介质中井-含水层-隔水层的潮汐水位振幅和位相的计算公式推广到裂隙饱水岩体潮汐分析中,分析了裂隙含水层中井与裂隙,裂隙与微裂隙的潮汐孔压响应原理和水流交换过程,提取了影响裂隙含水层潮汐水位振幅和位相的主要因素,应用井-裂隙排水产生的井水位引潮高的振幅比A和位相差a2主要随径向等效导水系数T同向变化,裂隙和微裂隙(孔隙)排水产生的孔压-引潮高的振幅比D和位相差a1主要随不排水条件下微裂隙与裂隙间振幅比E' /E反向变化的规律,提出了潮汐井水位振幅和位相的8种不同变化类型,分析了不同类型所反映的含水层形变,并用于分析东川、弥勒和西昌川03等3口井井水位振幅和位相变化的成因.     

潮汐水位振幅和位相变化研究及其在地下水异常分析中的应用

将多孔介质中井-含水层-隔水层的潮汐水位振幅和位相的计算公式推广到裂隙饱水岩体潮汐分析中, 分析了裂隙含水层中井与裂隙, 裂隙与微裂隙的潮汐孔压响应原理和水流交换过程, 提取了影响裂隙含水层潮汐水位振幅和位相的主要因素, 应用井-裂隙排水产生的井水位-引潮高的振幅比A和位相差α₂主要随径向等效导水系数T同向变化, 裂隙和微裂隙(孔隙)排水产生的孔压-引潮高的振幅比D和位相差α₁主要随不排水条件下微裂隙与裂隙间振幅比E'/E反向变化的规律, 提出了潮汐井水位振幅和位相的8种不同变化类型, 分析了不同类型所反映的含水层形变, 并用于分析东川、 弥勒和西昌川03等3口井井水位振幅和位相变化的成因.      

深井水位的固体潮效应

本文从体应变固体潮对深井水位影响的偏微分方程出发,考虑到含水层和井孔之间相互渗流的边界条件,用叠加原理、冲量定理和分离变量法等方法得出了方程的解.通过对这个解中水井含水层参数给予一些可能的值进行数值计算,讨论了水井固体潮系数和位相滞后与水井含水层参数间的关系,较好地解释了井水位对固体潮响应的位相滞后现象.计算表明,井孔的半径、含水层的孔隙度及固体骨架的体压缩系数愈大,含水的导水系数愈小,则水井水位的固体潮系数愈小,而水位对固体潮响应的位相滞后愈大.井水对长周期的潮汐响应比对短周期的更好.      

井孔变径与井水位的固体潮效应

根据多孔介质渗流理论和弹性理论，在井孔变径条件下，得出水井含水层系统对潮汐信号响应的偏微分方程，认为井径变化相当于改变了井水柱的有效高度，从而影响了水井含水层系统的固有振动周期。分析了井孔变径对潮汐信号响应的周期特征，认为当含水层水体很大（含水层水平面积比井孔面积大得多），且含水层的渗透系数也很大的条件下，井径变化对井水位固体潮响应幅度影响很小     

用重锤试验求承压含水层的水文地质参数

井孔响应试验通常指重锤试验,即测量井中水位突然变化时引起的井孔—含水层系统的强迫—自由振动响应。在许多情况下,它能可靠地确定含水层导水系数和其它特性。根据理论计算,该试验法影响范围一般可达100m。井孔—含水层系统的响应特性可分为三类:过阻尼振荡,临介阻尼振荡和欠阻尼振荡。 我们使用数值拉普拉斯变换方法,应用Cooper有关瞬时取水过阻尼响应的理论,计算出给定井孔—含水层系统模型对瞬间取水响应的理论曲线,然后将实际观测曲线与理论曲线对比,就能求出含水层的导水系数和弹性贮水系数。文中列出的三口测井用重锤试验求出的导水系数与抽水试验结果对比发现,数值相差较大,可能是由于实际含水层并非理想模型,或是给出的含水层厚度误差较大,致使计算结果误差较大。据Van der kamp有关欠阻尼响应的理论,计算出井孔—含水层系统的振动特性和响应能力,如角频率、阻尼系数和导水系数等。 井孔响应试验的显著特点是经济,简便,很多井的试验在数分钟之内即可完成。     

相邻两井对大地震的不同水力响应模型研究——页岩影响分析

大地震引起了左家庄和宝坻(相距～50km)两井中截然不同的同震水位响应.我们用水位的气压和潮汐响应来分析解释此现象.结果表明,宝坻井的观测含水层中存在页岩,且此井受裂隙影响很大,储水效应较差.页岩的复杂裂隙或者各向异性可能会导致此井观测含水层处于半封闭状态,从而导致垂直向排水的发生.通过多方计算分析后,我们将这两口井划分为两种模型—1.水平流动模型;2.水平流动+垂直流动的混合流动模型.由于裂隙影响,宝坻井的观测含水层介质与外界的水力沟通性在震前就较强(震前渗透率就比较大),所以宝坻井观测含水层与外界的孔隙压差异较小,导致同震渗透率上升较小甚至没有变化,这些因素是导致该井同震水位变化幅度总是非常微小的原因.     

地震波作用引起的井-含水层系统渗透率变化

正当井-含水层系统处于封闭性良好的承压体系中时,可视为一个天然体应变仪,外力作用引起含水层介质体应变的微小变化,井水位都能灵敏的做出响应。远场地震引起的井水位产生的水震波是地震波作用于井-含水层系统最直接的体现形式之一。国内外学者在水震波响应机理研究方面取得了很多进展,Cooper等(1965)研究了水位对地震波的影响因素,认为影响水位对地震波响应的因素有井孔的尺寸、含水层的导水系数、贮水系数、孔隙度以及波的类型等,并     

井-含水层系统对固体潮的动态响应及其影响因素

长期以来对于井水位固体潮的研究主要是建立在瞬时响应基础上的,鉴于瞬时响应模型不能反映井-含水层系统对固体潮响应的真实过程及含水层水力学特性对水位潮汐的影响,本文提出了动态响应模型,系统地研究了井-含水层系统对固体潮的动态响应过程及其影响因素。通过对井水位潮汐动态过程的研究,可以了解含水层的水文地质特征。井-含水层系统作为灵敏的体应变仪,井水位异常变化反映了地下应力、应变的变化。监测地下水位变化,只有在对井水位固体潮等正常背景有了明确的认识后,才有可能从水位变化中排除正常干扰,得到可靠的异常信息。 本文将在研究含水层渗透性、贮水率、井径、含水层厚度及潮汐频率对水位潮汐影响的基础上,研究井-含水层系统对固体潮响应的动态过程,力求反映井水位潮汐的真实图象。     

鲁—14井井径变化试验的解释

对鲁－14井井径变化试验的井水位潮汐资源进行了反复调和分析，结果表明试验前后井水位对气压和固体潮的响应改变较小。根据多孔介质渗流理论和弹性理论，对这一现象进行了解释，认为井径变化相当于改变了井水柱的有效高度，从而影响了水井含水层系统的固有振动周期。分析了井孔变径对潮汐信号响应的周期特征，认为在含水层水体很大（含水层水平面积比井孔面积大得多），且含水层的渗透系数也很大的条件下，井径变化对井水位畦体潮响应幅度影响很小。     

华蓥山地区4口井水位潮汐动态特征研究

本文选择沿华蓥山断裂带分布的荣昌等4口观测井,利用Baytap-G潮汐分析方法,计算各井水位和气压及理论固体潮的潮汐振幅谱,比较其潮汐频谱差异,通过对主要潮汐分波振幅的回归计算定量分析各井水位受气压潮和固体潮影响的大小。基于对井水位正常动态的认识,选择各井水位潮汐的主要分波,对井水位长时序数据进行分析计算,提取水位潮汐响应特征参数(振幅比和相位差),进而探讨特征参数动态变化特征。最后对井水位受气压潮和固体潮影响的差异原因进行了初步探讨。结果表明,荣昌井水位主要受气压作用的影响,北碚、大足、南溪三口井水位受固体潮-气压潮综合作用的影响,而荣昌井水位只受气压潮影响可能与该井所处含水层裂隙发育且该井未下设止水套管有关;荣昌井P_1S_1K_1波和南溪井M_2波振幅比和相位差在几次大震后没有明显变化,说明地震波没有使井孔与含水层之间的水流交换发生显著变化,而北碚井和大足井M_2波振幅比和相位差分别在汶川和芦山地震时发生变化,反映了地震波的疏通影响。     

中国大陆井水温度潮汐动态的统计与调和分析

用收集到的全国356个井水温度测点的数据, 分析了水温对地球固体潮汐的响应, 统计出 35个存在水温潮汐现象的测点。 利用Baytap-G调和分析方法, 计算了水温潮汐分波的振幅、 振幅比和相位差。 结果表明: 水温潮汐现象是一类较普遍的地球物理现象, 其机制与水位潮汐相关, 可用水动力学模式解释; 水温潮汐变化特征还受太阳辐射热、 含水层和地温的影响, 自流井水温记录潮汐现象的能力高于非自流井、 东部地区水温测点记录潮汐现象的能力高于西部, 与太阳辐射热的影响有关, 在含水层附近的水温测点, 其潮汐动态比其他井段显著, 在受地温影响较大的井段, 水温的潮汐变化幅度与水温梯度成正比; 水温的应力-应变灵敏度量级为0.01～10℃/10^-6m·s^-2。     

川滇地区井水位潮汐响应特性分析

利用Baytap-G潮汐分析软件对川滇地区12口观测井数字化水位的长时序数据进行计算, 提取井水位潮汐响应特征参数(振幅比和相位差), 分析其形态、 阶段变化等特征, 探讨地震前后井水位潮汐响应特征参数的变化情况, 为深入分析井水位与固体潮、 气压之间响应关系的研究提供新的方法和途径。 结果表明, 泸沽湖井等10口受固体潮影响的井水位振幅比和相位差变化相对稳定; 而南溪井和大姚井受到气压-固体潮综合作用影响的井水位振幅比和相位差变化则比较离散。 其中江油川10井、 泸沽湖井、 东川井等3口井水位振幅比和相位差对大震的响应显著, 并给出了地震能量密度与这三口井水位M₂波相位差和振幅比的变化关系。     

Determination of aquifer parameters based on measurements of tidal effects on a coastal aquifer near Beihai,China

Measurements of the tide and groundwater levels in coastal zones are of importance in determining the properties of coastal aquifers. The solution to a one‐dimensional unsteady groundwater flow model in a coastal confined aquifer with sinusoidal fluctuation of the tide shows that the tidal efficiency decreases exponentially with distance and the time lag increases linearly with distance from the coast. The aquifer property described by the ratio of storage coefficient to transmissivity is determined if the damping constant of the tidal efficiency or the slope of the time lag with distance are obtained on the basis of tidal measurements. Hourly observations of the tide and groundwater levels at 10 wells on the northern coast near Beihai, China show that with distance from the coast, tidal efficiency decreases roughly exponentially and the time lag increases roughly linearly. The estimated ratio of storage coefficient to transmissivity of the confined aquifer ranges from 1·169 × 10^?6 d m^?2 to 1·83 × 10^?7 d m^?2. For a given transmissivity of 750 m² d^?1, the storage coefficient of the aquifer is 8·7675 × 10^?4 with the tidal efficiency method and 1·3725 × 10^?4 with the time lag method. The damping constant of the tidal efficiency with distance can be defined as the tidal propagation coefficient. The value of the confined aquifer is determined as 0·0018892 m^?1. Copyright © 2007 John Wiley & Sons, Ltd.     

井-含水层系统地下水类型定量分析和判别

利用水位、 气压和理论固体潮数据, 采用卷积回归法中水位对气压的阶跃响应函数， 定量地分析和判定了华北北部板桥井、 大灰厂井、 黄骅井、 大甸子井、 丰镇井和三号地井的井-含水层系统的地下水类型， 并结合研究时段内各井的气压系数和M₂波潮汐因子的结果进行了对比分析． 结果表明: ① 各井的滞后时间与阶跃响应函数之间存在明显的以e为底的指数函数关系， 且底数e的系数的正负决定了井-含水层系统的地下水类型； ② 承压井的阶跃响应函数随滞后时间的增大而增大， 且最佳阶跃响应函数值越大， 相应的气压系数和M₂波潮汐因子也越大， 反之亦然； ③ 潜水井和半承压水井的阶跃响应函数随滞后时间的增大而减小， 其最佳阶跃响应函数与气压系数和M₂波潮汐因子间的关系不明显， 可能与含水层的水力特性、 井孔结构及固体潮汐波的频率有关．      

Non-Darcian flow in a single confined vertical fracture toward a well

Non-Darcian flow towards a well which fully penetrates a confined single vertical fracture is presented in this paper on the basis of the Izbash equation. We have obtained semi-analytical solutions for non-Darcian flow by using the Boltzmann transform and developed the non-Darcian flow well functions for cases with and without the effect of wellbore storage. The results show that the non-Darcian flow type curves are more or less deviated from the Darcian flow type curve. The non-linear effect is mainly attributable to the turbulent factor, v, a dimensionless parameter related to the pumping rate, the fracture aperture, the fracture thickness, and two constants k′ and n used in the Izbash power-law. The non-linear effect appears to be less sensitive to the power-law index, n. When excluding wellbore storage, the well function at early times is proportional to v^−1/(n−1)u^−n/(n−1), where u is a dimensionless term inversely proportional to time; whereas the well function at late times is approximated as , where A₀(n) is a finite term depending on n. When considering wellbore storage, drawdowns inside the well with different v values approach the same asymptotic value at small times, and the effect of wellbore storage is only found at the early stage of pumping.     

Analytical studies of groundwater-head fluctuation in a coastal confined aquifer overlain by a semi-permeable layer with storage

Analytical studies are carried out to investigate groundwater-head changes in a coastal aquifer system in response to tidal fluctuations. The system consists of an unconfined aquifer, a semi-confined aquifer and a semi-permeable confining unit between them. An exact analytical solution is derived to investigate the influences of both leakage and storage of the semi-permeable layer on the tide-induced groundwater-head fluctuation in the semi-confined aquifer. This solution is a generalization of the solution obtained by Jiao and Tang (Water Resource Research 35 (1999) 747–751) which ignored the storage of the semi-confining unit. The analytical solution indicates that both storage and leakage of the semi-permeable layer play an important role in the groundwater-head fluctuation in the confined aquifer. While leakage is generally more important than storage, the impact of storage on groundwater-head fluctuations changes with leakage. With the increase of leakage the fluctuation of groundwater-head in the confined aquifer will be controlled mainly by leakage. The study also demonstrates that the influence of storativity of the semi-permeable layer on groundwater-head fluctuation is negligible only when the storativity of the semi-permeable layer is comparable to or smaller than that of the confined aquifer. However, for aquifer systems with semi-permeable layer composed of thick, soft sedimentary materials, the storativity of the semi-permeable layer is usually much greater than that of the aquifer and its influence should be considered.     

Some analytical solutions for sensitivity of well tests to variations in storativity and transmissivity

The theory of a pumping test or a slug test to measure aquifer transmissivity or storativity assumes that the aquifer properties are uniform around the well. The response of the drawdown to small spatial variations in aquifer properties in the volume of influence is determined by spatial weighting functions or Fréchet kernels, which in general are functions of space and time. The Fréchet kernels determine the effective “volume of influence” of the measurements at any time. Under the assumption that the well is a line sink we derive explicit analytical expressions for the Fréchet kernels for storativity and for transmissivity for both pumping and slug tests. We also derive the total sensitivity functions for uniform variations in storativity and transmissivity and show that they are the spatial integrals of the Fréchet kernels. We consider both the case of separate pumping and observation wells and also the radially symmetric case of observations made at the pumped or slugged well. The “volume of influence” is symmetric with respect to the pumping or slugged well and the observation well, and far from the well the contours of equal spatial sensitivity approach the shapes of ellipses with a well at each focus, rather than circles centered on the pumping well. We use the analytical solutions to investigate the nature of the singularities in the spatial sensitivity functions around the wells, which govern the importance of inhomogeneities close to the well or observation point.     

气压变化及其对地壳形变和深井水位的影响

根据北京塔院地区1984和1985年的微气压计记录采用频谱分析和调和分析两种方法得出了大气潮谱的详细结构;用负荷勒甫数代替潮汐勒甫数,仿照固体潮的有关公式,导出了大气潮引起的地壳应变和地倾斜公式;使用北京塔院井的水位观测资料结合当地的气压资料,分析了气压变化对深井水位的影响.理论计算和实测资料的分析结果基本相符,特别是两种结果都得出S₂大气潮引起的体膨胀约为S₂固体潮体膨胀的20％.     

Joint simulation of transmissivity and storativity fields conditional to steady-state and transient hydraulic head data

The self-calibrated method has been extended for the generation of equally likely realizations of transmissivity and storativity conditional to transmissivity and storativity data and to steady-state and transient hydraulic head data. Conditioning to transmissivity and storativity data is achieved by means of standard geostatistical co-simulation algorithms, whereas conditioning to hydraulic head data, given its non-linear relation to transmissivity and storativity, is achieved through non-linear optimization, similar to standard inverse algorithms. The algorithm is demonstrated in a synthetic study based on data from the WIPP site in New Mexico. Seven alternative scenarios are investigated, generating 100 realizations for each of them. The differences among the scenarios range from the number of conditioning data, to their spatial configuration, to the pumping strategies at the pumping wells. In all scenarios, the self-calibrated algorithm is able to generate transmissivity–storativity realization couples conditional to all the sample data. For the specific case studied here the results are not surprising. Of the piezometric head data, the steady-state values are the most consequential for transmissivity characterization. Conditioning to transient head data only introduces local adjustments on the transmissivity fields and serves to improve the characterization of the storativity fields.