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Water Quality Variations for Pumping Wells 总被引：3，自引：0，他引：3
Kenneth D. Schmidt 《Ground water》1977,15(2):130-137
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Explicit algebraic equations are derived to determine approximate maximum pumping rates or minimum injection rates to limit sea water intrusion to a prespecified distance from the coastline. The equations are based on Strack's (1976) single-potential solution. The maximum pumping rates and minimum injection rates applied at wells with uniform spacing to control the inland movement of the fresh water-salt water interface in a coastal aquifer could be calculated from Strack's (1976) solution without the need of a numerical optimization algorithm. When wells are distributed in a simple fashion, the maximum intrusion location can be identified precisely for pumping cases and approximately for injection cases. For pumping cases, critical points are the limit of allowable salt water intrusion, whereas no such limit exists for injection cases. Once an application site is identified, a series of design curves for pumping and injection rates can be developed for arbitrary intrusion limits. When a user is interested only in the largest pumping rates associated with critical points, one design curve can yield complete information. 相似文献
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《Ground Water Monitoring & Remediation》1986,6(3):64-67
The DuPont Victoria Texas plant has gained 195 well-years of experience in operating and maintaining underground injection wells since 1953. This experience demonstrates that it is very important to locate wells where proper geology exists for ground water protection. The well construction features and materials are equally important. Well operation at this plant features a leak detection system that continuously monitors the mechanical integrity of the wells. The evaluation of these monitoring data provides early detection of problems before the environment can be harmed. Investigation and diagnostic techniques are then used to determine the nature and exact location of problems, whether they exist at the surface or downhole in the injection tubing, packer or casing. Once the problem is defined, remedial action is instituted. Finally the success of the repair is confirmed through additional testing.
Only a limited number of repairs have been required over the past 33 years and all have been carried out without endangering the environment. 相似文献
Only a limited number of repairs have been required over the past 33 years and all have been carried out without endangering the environment. 相似文献
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Ferenc Székely 《Ground water》2013,51(5):762-767
The vertical variation of drawdown around pumping wells generates an induced flow in the observation wells. A set of governing equations is presented to couple the drawdown variation and the vertical flux distribution in observation wells. A numerical example is performed to justify the governing equations and to verify the solution methods used by the simulation software WT. The example analyzes the effect of skin loss, wellbore storage, and vertical segmentation on the drawdown and induced flow in observation well during pumping. The evaluation of the Fairborn pumping test involves a vertically homogeneous and anisotropic water table aquifer, uniform well‐face drawdown conditions in the pumping well and simulation of the drawdown evolution in the observation well with and without the effect of induced flow. The computer calibrations resulted in small differences between the measured and simulated drawdown curves. 相似文献
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《Ground Water Monitoring & Remediation》2008,28(2):75-80
In a recent field study, the performance of four production wells was evaluated. The intake of a vertical turbine test pump was set below the top of the screened interval of the wells due to anticipated drawdown. Water level sounding tubes were welded to the well casing at various depths in each well. Drawdown data collected at various depths were used to evaluate the vertical head distribution in the wells under various pumping stresses. A direct relationship was observed between the head loss and the location of the pump intake in the production wells. A vertical head profile developed, suggesting that the location of the pump intake controlled the location of water production from the aquifer. The head loss in the wells observed during pumping was directly proportional to well discharge and annulus size between the well casing and the vertical turbine pump shaft. The pressure differences that developed in the wells created increased drawdown in water level sounding tubes installed deep in the wells compared to the total drawdown observed in the production wells. Certain implications should be considered based on the evaluation of the data obtained from this study. Because water management decisions are made using well test data, the quality of the data is crucial. In instances where well performance is evaluated using water level data collected from water level sounding tubes that are located close to a pump intake (in this case deep in the well), it should be recognized that well performance could be underestimated. 相似文献
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Frank A. Rayner 《Ground water》1981,19(1):103-104
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Pieter S. Pauw Sjoerd E.A.T.M. van der Zee Anton Leijnse Gualbert H.P. Oude Essink 《Ground water》2016,54(4):521-531
This article deals with the quantification of saltwater upconing below horizontal wells in freshwater lenses using analytical solutions as a computationally fast alternative to numerical simulations. Comparisons between analytical calculations and numerical simulations are presented regarding three aspects: (1) cyclic pumping; (2) dispersion; and (3) finite horizontal wells in a finite domain (a freshwater lens). Various hydrogeological conditions and pumping regimes within a dry half year are considered. The results show that the influence of elastic and phreatic storage (which are not taken into account in the analytical solutions) on the upconing of the interface is minimal. Furthermore, the analytical calculations based on the interface approach compare well with numerical simulations as long as the dimensionless interface upconing is below 1/3, which is in line with previous studies on steady pumping. Superimposing an analytical solution for mixing by dispersion below the well over an analytical solution based on the interface approach is appropriate in case the vertical flow velocity around the interface is nearly constant but should not be used for estimating the salinity of the pumped groundwater. The analytical calculations of interface upconing below a finite horizontal well compare well with the numerical simulations in case the distance between the horizontal well and the initial interface does not vary significantly along the well and in case the natural fluctuation of the freshwater lens is small. In order to maintain a low level of salinity in the well during a dry half year, the dimensionless analytically calculated interface upconing should stay below 0.25. 相似文献
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M. Wojciech Kawecki 《Ground water》2011,49(3):445-449
Traditional methods of analyzing pumping tests in single wells fail when the well loss is very high due to a low transmissivity skin. Because of the restricted rate at which water can enter a high loss well from the aquifer, well casing storage becomes a significant factor. Additionally, if a slug of water enters the well from the pump column immediately after the pump is switched off, it has a long‐lasting significant effect on the recovering water level in the well because it cannot be absorbed rapidly by the aquifer. A theoretical model is derived here that simulates the water level in a well in these circumstances. In the model, the continuously changing rate of water inflow from the aquifer to the well is approximated by a step function with a finite difference time step. It is demonstrated by a real example that the model can be applied easily to analyze pumping tests, including tests with a varying pumping rate. The analysis confirms suspected high well loss, calculates the unknown rate of backflow, and determines the aquifer's transmissivity. 相似文献
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Festus F. Akindunni Robert W. Gillham Brewster Conant Jr. Thomas Franz 《Ground water》1995,33(2):264-274
A transient axisymmetric saturated-unsaturated numerical flow model was coupled with a particle tracking model to investigate the movement of contaminants when a shallow unconfined aquifer is pumped at a constant rate. The particle tracking model keeps track of locations and masses of solutes in the aquifer, and the time of capture by the well. At the end of each time-step the flow model solves the Richard's equation for the hydraulic head distribution from which elemental velocities are calculated. Solutes are then displaced for a period equivalent to the time-step using both the magnitude and direction of the elemental velocities. Numerical experiments were performed to investigate effluent concentrations in wells with screens of different length and in different positions relative to zones of stratified contamination. At early times of pumping the effluent concentrations were similar to the concentrations adjacent to the well screen, but at late times, the concentrations approached the vertically averaged concentration in the aquifer. Time to attain the vertically averaged concentration was determined by the well geometry, initial location of the contaminant plume in relation to the well screen, and hydraulic properties of the aquifer. The results are consistent with the hydraulics of flow to a pumping well and of particular importance, they demonstrate that short-term pump tests could give erroneous design concentrations for pump-and-treat systems. The model provides a means of quantifying arrival times and mixing ratios. It could therefore provide a useful means of designing production wells in aquifers with stratified contamination and more efficient recovery systems for aquifer remediation. 相似文献
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Analytical Solutions for Gas Flow Due to Gas Injection and Extraction from Horizontal Wells 总被引：2，自引：0，他引：2
Ronald W. Falta 《Ground water》1995,33(2):235-246
Analytical solutions are developed for modeling the transient and steady-state gas pressure and the steady-state streamfunction fields resulting from gas injection and extraction from a pair of parallel horizontal wells. These solutions apply to cases in which the ground surface is open to the atmosphere, and in which the porous media is anisotropic but homogeneous. By neglecting end effects due to the finite length of the wells, the three-dimensional gas flow field is approximated as a two-dimensional cross section perpendicular to the wells. These solutions may be used to develop estimates of the horizontal well system behavior and to analyze horizontal well gas pump tests, and are useful for numerical model verification. 相似文献