共查询到20条相似文献,搜索用时 15 毫秒
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The Nguyen and Pinder method is one of four techniques commonly used for analysis of response data from slug tests. Limited field research has raised questions about the reliability of the parameter estimates obtained with this method. A theoretical evaluation of this technique reveals that errors were made in the derivation of the analytical solution upon which the technique is based. Simulation and field examples show that the errors result in parameter estimates that can differ from actual values by orders of magnitude. These findings indicate that the Nguyen and Pinder method should no longer be a tool in the repertoire of the field hydrogeologist. If data from a slug test performed in a partially penetrating well in a confined aquifer need to be analyzed, recent work has shown that the Hvorslev method is the best alternative among the commonly used techniques. 相似文献
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J.J. Butler Jr S. Knobbe E.C. Reboulet D.O. Whittemore B.B. Wilson G.C. Bohling 《Ground water》2021,59(6):808-818
Many of the world's major aquifers are under severe stress as a result of intensive pumping to support irrigated agriculture and provide drinking water supplies for millions. The question of what the future holds for these aquifers is one of global importance. Without better information about subsurface conditions, it will be difficult to reliably assess an aquifer's response to management actions and climatic stresses. One important but underutilized source of information is the data from monitoring well networks that provide near-continuous records of water levels through time. Most organizations running these networks are, by necessity, primarily focused on network maintenance. The result is that relatively little attention is given to interpretation of the acquired hydrographs. However, embedded in those hydrographs is valuable information about subsurface conditions and aquifer responses to natural and anthropogenic stresses. We demonstrate the range of insights that can be gleaned from such hydrographs using data from the High Plains aquifer index well network of the Kansas Geological Survey. We show how information about an aquifer's hydraulic state and lateral extent, the nature of recharge, the hydraulic connection to the aquifer and nearby pumping wells, and the expected response to conservation-based pumping reductions can be extracted from these hydrographs. The value of this information is dependent on accurate water-level measurements; errors in those measurements can make it difficult to fully exploit the insights that water-well hydrographs can provide. We therefore conclude by presenting measures that can help reduce the potential for such errors. 相似文献
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A B‐Spline Framework for Smooth Derivative Computation in Well Test Analysis Using Diagnostic Plots 下载免费PDF全文
In the oil and gas industry, well test analysis using derivative plots, has been the core technique in examining reservoir and well behavior over the last three decades. Recently, diagnostics plots have gained recognition in the field of hydrogeology; however, this tool is still underused by groundwater professionals. The foremost drawback is that the derivative function must be computed from noisy field measurements, usually based on finite‐difference schemes, which complicates the analysis. We propose a B‐spline framework for smooth derivative computation, referred to as Constrained Quartic B‐Splines with Free Knots. The approach presents the following novelties in relation to methodological precedents: (1) the use of automatic equality derivative constraints, (2) a knot removal strategy and (3) the introduction of a Boolean shape parameter that defines the number of initial knots to choose. These can lead to evaluate both simple (manually recorded drawdown measurements) and complex (transducer measured records) datasets. Furthermore, we propose an additional shape preserving smoothing preprocess procedure, as a simple, fast and robust method to deal with extremely noisy signals. Our framework was tested in four pumping tests by comparing the spline derivative with regards to the Bourdet algorithm, and we found that the latter is rather noisy (even for large differentiation intervals) and the second derivative response is basically unreadable. In contrast, the spline first and second derivative led to smoother responses, which are more suitable for interpretation. We concluded that the proposed framework is a welcome contribution to evaluate reliable aquifer tests using derivative‐diagnostic plots. 相似文献
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David Meiri 《Ground Water Monitoring & Remediation》1989,9(2):78-81
A tracer test was used to evaluate whether cross contamination exists along a monitoring well completed through a shallow ground water system in fractured clay and screened in a sand and gravel aquifer. The fractured clay is separated from the sand and gravel deposit by a layer of highly plastic unfractured clay. A natural vertical downward hydraulic gradient of approximately 0.5 exists between the shallow system and the sand and gravel aquifer. Ground water contamination was detected in an adjacent monitoring well screened in the fractured clay and in the monitoring well screened in the sand and gravel deposit. No ground water contamination was apparent in an intermediate well screened in the unfractured clay layer. A tracer of sodium bromide was injected into a shallow boring near the monitoring wells. The tracer was detected in the monitoring well in the sand and gravel aquifer after three to seven days. The bromide concentration continued to increase in this well with time while the concentration in the shallow boring declined. This trend of tracer concentration indicates the tracer has in fact migrated downward and possibly traveled along the well column. 相似文献
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宁波台ZK03井气氡仪在2017年12月更新为BG2015测氡仪,2018年12月又增上ATG6138M痕量汞仪,两套仪器采用同一脱气装置,记录显示采用原系统气氡仪、气汞仪数据离散度大,分析原因是一方面该井流量逐年降低使原脱气装置显现弊端,由于设计缺陷集气室进水量小造成原出水口不能实现水封空气出现跑气现象;另一方面ATG6138M痕量汞仪设计有定时吸气功能,原装置液面与脱气口间距小,部分水汽吸入仪器,引起仪器工作不稳定。为此,该台进行针对性设计改造,监测数据显示此次改造解决了原脱气装置缺陷,取得良好的效果。 相似文献
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Ekkehard Holzbecher 《Ground water》2013,51(1):128-134
For a well in the vicinity of a surface water body, a formula is developed that relates the share of bank filtrate on total pumpage, that is, the discharge ratio, on one side, to basic well and aquifer characteristics on the other. The application of the formula is demonstrated for solving the inverse problem: for an aimed discharge ratio, well characteristics (pumping rate, distance to shore) can be determined. Other useful applications of the formula are outlined. 相似文献