- Email: [email protected]
Sensitivity analysis of slug tests. Part 2. Observation wells
HYDROGEOLOGYzWATER from unlined canals. Return flow from irrigation aad infiltration from rainfall contribute to the replenishment of the water table. The seepage from all these sources leads to build-up of the water table creating the problem of waterlogging and salinity. Aa analytical solution to the problem of water table rise in a finite length phreatic aquifer based on appropriate transformations is obtained. The proposed solution is simpler thaa the available solution aad for the selected illustrative auaierical example gives fairly close results. (Authors) 956079
Simulation of groundwater interception at Lake Ranfurly, Victoria, incorporating variable density flow and solute transport K. A. Narayaa & D. Armstrong, Journal of Hydrology, 165(1-4), 1995, pp 161-184. The movement of salt from Lake Ranfurly West towards the River Murray and the associated groundwater interception scheme has been modelled in cross-section using the SUTRA model. Concentration profiles in the aquifers aad salt loads to the river under various management scenarios were computed under conditions of both density-dependent and aoadeasitydependeat flow. The model siamlatioas have shown that the salt load to the river is: 1) dependent on the rate of pumping from interception bores, 2) dependent on the aquifer(s) in which grouadwater is intercepted, aad 3) marginally greater for density-dependent Bow behaviour at less than full interception compared with calculations which neglect deasitydepeadeat flow. (Authors) 956080 Uranium (VI) adsorption to ferrihydritez application of a surface complexation model T. D. Waite, J. A. Davis, T. E. Payne, G. A. Waychunas & N. Xu, Geochimica et Cosmochimica Acta, 58(24), 1994, pp 5465-5478. The mobility of U in water-rock systems is dependent both upon its ability to form insoluble precipitates and, particularly at relative low total uranium coaceatratioas, upon its tendency to adsorb to solid substrates. In this study U(VI) adsorption by ferrihydrite was observed over a wide range of U(Vl) concentrations, pH, aad at two partial pressures of carbon dioxide. A two-site surface complexatioa model was able to describe the experimental data well over a wide raage of conditions. The results demonstrate that the speciatioa of adsorbed U(VI) may be constrained by the coordination environment at the surface, giving rise to surface speciatioa for U(VI) that is significantly less complex than aqueous speciatioa. (from Authors)
Measurement of water pressure and its effects
PRESSURE
261A
magnitude of the error arising in a variety of commonly faced field wafiguratioas is the basis for practical guidelines for the analysis of slug-test data that caa be utilized by field practitioners. (from Authors) 956082 Sensitivity 8aalysis of slug tests. Part 1. The slugged well C. D. McElwee, G. C. Bohling & J. J. Butler Jr, Journal of Hydrology, 164(1-4), 1995, pp 53-67. The techniques of sensitivity analysis are applied to the Cooper et al. model for slug tests in confined aquifers. The sensitivity analysis enables a family of generic sensitivity coellicieats for transmissivity (2’) aad storage coefficient (s) to be defined by two parameters a (related to 5’)and 8 (related to time aad 7’). Generally, aa increased number of measuremeats improved parameter estimation, if properly placed in time. (from Authors) 956083 Sensitivity analysis of slug tests. Part 2. Observation wells C. D. McElwee, J. J. Butler Jr, G. C. Bohliag & W. Liu, Journal of Hyrbology, 164(1-4), 1995, pp 69-87. An investigation of the radial dependence of the Cooper et al. analytical solution for a slug test in a confined aquifer shows that the use of one or more observation wells caa vastly improve the parameter estimates, particularly the estimate of the storage parameter. Generally, the observation well must be fairly close (about 10 m or less) to the slugged well to be effective. The storage coefficient must be small in order to see the effect of the slug at greeter distances from the stressed well. Since the temporal aad spatial dependence of the sensitivities for transmissivity and storage are considerably different, the addition of one or more observation wells will substantially reduce the correlation between these two parameters, which will result in much better estimates than are usually obtained in slug tests. (from Authors) 956084 Estimation of statistical parameters for censored lognormal hydraulic conductivity measurements Xiaa-Huaa Wea, Mathematical Geology, 26(6), 1994, pp 717-731. Field tests of hydraulic conductivity in low permeability formations are subject to censoring due to the detection liarit of the iastrumeats used. An iterative method of estimating the mesa aad variance of hydraulic conductivity data with a presumed log-normal distribution function is presented. This method accounts for data below the lower detection limit aad thus gives distribution parameters that are more representative for the underlying distribution. The pmposed method is tested on two simulated normally distributed random datasets having different variaaces. The results show that the means aad variaaces estimated by the proposed method are very accurate. (from Author)
956OfIl Slug tests in partially penetrating wells Z. Hyder, J. J. Butler Jr, C. D. McElwee & Wenxhi Liu, Water Resources Research, 30(11), 1994, pp 2945-2957.
956085 The electric and hydraulic anisotropic behavior of the Jeanne d’Arc Basin reservoirs H. S. Salem, Journal of Petroleum Science & Engineering, 12(l), 1994, pp 49-66.
The slug test is one of the most commonly used techniques by hydrogeologists for estimating hydraulic conductivity in the field. This technique, consists of measuring the recovery of head in a well after a near instantaneous change in water level at that well. In this paper a semianalytical solution is presented to a mathematical model describing the flow of grouadwater in response to a slug test in a confined or unconfined porous formation. The model is employed to investigate the error that is introduced into hydraulic conductivity estimates through use of currently accepted pr-%Xice~ for the analysis of slug-test response data. The
This study attempts to ntauerically determine the electric and hydraulic aaisotropies produced by watrasts in electric aad hydraulic coaductivities when electric and hydraulic currents flow along aad perpendicular to the bedding planes. This study was carried out for reservoirs in 14 Hihernia and Terra Nova wells in the Jeanne d’Arc Basin (JDB), offshore Newfoundland, Canada. Determination of electric anisotropy coefficients and hydraulic anisotropy coefficients indicates that permeability shows more contrast ia the horizontal and vertical directions than resistivity. Tortuosity, electrolyte salinity, water-hydrocarbon saturation, orientation of
Simulation of groundwater interception at Lake Ranfurly, Victoria, incorporating variable density flow and solute transport K. A. Narayaa & D. Armstrong, Journal of Hydrology, 165(1-4), 1995, pp 161-184. The movement of salt from Lake Ranfurly West towards the River Murray and the associated groundwater interception scheme has been modelled in cross-section using the SUTRA model. Concentration profiles in the aquifers aad salt loads to the river under various management scenarios were computed under conditions of both density-dependent and aoadeasitydependeat flow. The model siamlatioas have shown that the salt load to the river is: 1) dependent on the rate of pumping from interception bores, 2) dependent on the aquifer(s) in which grouadwater is intercepted, aad 3) marginally greater for density-dependent Bow behaviour at less than full interception compared with calculations which neglect deasitydepeadeat flow. (Authors) 956080 Uranium (VI) adsorption to ferrihydritez application of a surface complexation model T. D. Waite, J. A. Davis, T. E. Payne, G. A. Waychunas & N. Xu, Geochimica et Cosmochimica Acta, 58(24), 1994, pp 5465-5478. The mobility of U in water-rock systems is dependent both upon its ability to form insoluble precipitates and, particularly at relative low total uranium coaceatratioas, upon its tendency to adsorb to solid substrates. In this study U(VI) adsorption by ferrihydrite was observed over a wide range of U(Vl) concentrations, pH, aad at two partial pressures of carbon dioxide. A two-site surface complexatioa model was able to describe the experimental data well over a wide raage of conditions. The results demonstrate that the speciatioa of adsorbed U(VI) may be constrained by the coordination environment at the surface, giving rise to surface speciatioa for U(VI) that is significantly less complex than aqueous speciatioa. (from Authors)
Measurement of water pressure and its effects
PRESSURE
261A
magnitude of the error arising in a variety of commonly faced field wafiguratioas is the basis for practical guidelines for the analysis of slug-test data that caa be utilized by field practitioners. (from Authors) 956082 Sensitivity 8aalysis of slug tests. Part 1. The slugged well C. D. McElwee, G. C. Bohling & J. J. Butler Jr, Journal of Hydrology, 164(1-4), 1995, pp 53-67. The techniques of sensitivity analysis are applied to the Cooper et al. model for slug tests in confined aquifers. The sensitivity analysis enables a family of generic sensitivity coellicieats for transmissivity (2’) aad storage coefficient (s) to be defined by two parameters a (related to 5’)and 8 (related to time aad 7’). Generally, aa increased number of measuremeats improved parameter estimation, if properly placed in time. (from Authors) 956083 Sensitivity analysis of slug tests. Part 2. Observation wells C. D. McElwee, J. J. Butler Jr, G. C. Bohliag & W. Liu, Journal of Hyrbology, 164(1-4), 1995, pp 69-87. An investigation of the radial dependence of the Cooper et al. analytical solution for a slug test in a confined aquifer shows that the use of one or more observation wells caa vastly improve the parameter estimates, particularly the estimate of the storage parameter. Generally, the observation well must be fairly close (about 10 m or less) to the slugged well to be effective. The storage coefficient must be small in order to see the effect of the slug at greeter distances from the stressed well. Since the temporal aad spatial dependence of the sensitivities for transmissivity and storage are considerably different, the addition of one or more observation wells will substantially reduce the correlation between these two parameters, which will result in much better estimates than are usually obtained in slug tests. (from Authors) 956084 Estimation of statistical parameters for censored lognormal hydraulic conductivity measurements Xiaa-Huaa Wea, Mathematical Geology, 26(6), 1994, pp 717-731. Field tests of hydraulic conductivity in low permeability formations are subject to censoring due to the detection liarit of the iastrumeats used. An iterative method of estimating the mesa aad variance of hydraulic conductivity data with a presumed log-normal distribution function is presented. This method accounts for data below the lower detection limit aad thus gives distribution parameters that are more representative for the underlying distribution. The pmposed method is tested on two simulated normally distributed random datasets having different variaaces. The results show that the means aad variaaces estimated by the proposed method are very accurate. (from Author)
956OfIl Slug tests in partially penetrating wells Z. Hyder, J. J. Butler Jr, C. D. McElwee & Wenxhi Liu, Water Resources Research, 30(11), 1994, pp 2945-2957.
956085 The electric and hydraulic anisotropic behavior of the Jeanne d’Arc Basin reservoirs H. S. Salem, Journal of Petroleum Science & Engineering, 12(l), 1994, pp 49-66.
The slug test is one of the most commonly used techniques by hydrogeologists for estimating hydraulic conductivity in the field. This technique, consists of measuring the recovery of head in a well after a near instantaneous change in water level at that well. In this paper a semianalytical solution is presented to a mathematical model describing the flow of grouadwater in response to a slug test in a confined or unconfined porous formation. The model is employed to investigate the error that is introduced into hydraulic conductivity estimates through use of currently accepted pr-%Xice~ for the analysis of slug-test response data. The
This study attempts to ntauerically determine the electric and hydraulic aaisotropies produced by watrasts in electric aad hydraulic coaductivities when electric and hydraulic currents flow along aad perpendicular to the bedding planes. This study was carried out for reservoirs in 14 Hihernia and Terra Nova wells in the Jeanne d’Arc Basin (JDB), offshore Newfoundland, Canada. Determination of electric anisotropy coefficients and hydraulic anisotropy coefficients indicates that permeability shows more contrast ia the horizontal and vertical directions than resistivity. Tortuosity, electrolyte salinity, water-hydrocarbon saturation, orientation of