What information can we get from pumping tests?-comparing pumping test configurations using sensitivity coefficients

Leven, Carsten; Dietrich, Peter

doi:10.1016/j.jhydrol.2005.06.030

Cited by 58 publications

(62 citation statements)

References 40 publications

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“…However, compared to single-hole tests, the results have a higher degree of non-uniqueness. In the case of transmissivity, these observations have regions of positive and negative sensitivity (Leven et al 2006). Wh positive correlation between drawdown and transmissivity exists within a circular area between the observation wells, outside the circle the sensitivity is negative (Figure 3).…”

Section: Instrumentationmentioning

confidence: 96%

“…Particularly short type curves without a characteristic shape are susceptible to non-uniqueness (Daungkaew et al 2000), and require a careful interpretation with respect to the types of heterogeneities and their distance to the well. Single-hole tests have radially-symmetric negative sensitivity, in which the sensitive area increases with time (Leven et al 2006 Eq. (3), the radius of investigation is about 220 m. 50 C their spatial distributions and directions.…”

Section: Instrumentationmentioning

confidence: 99%

“…Therefore, the initial pressure response can be evaluated, and its sensitivity is particularly relevant. Initially, cross-hole tests are most sensitive to the region within between the pumping and observation wells (Leven et al 2006, Figure 3). With increasing duration, the sensitivity is shifted to areas further away from the circle and can be used for characterisation of more distant points in the aquifer (e.g.…”

Section: Instrumentationmentioning

confidence: 99%

“…However, the hydraulic parameters show significant differences in space, disproving the assumption of homogeneity. This contradiction was resolved by using the additional results from approach (iii) and interpreting them with consideration to spatially and temporally-dependent sensitivities (Leven et al 2006, Vasco et al 2000. The parameters identified in this manner were attributed to the area for which the method provided the most sensitive results.…”

Section: Introductionmentioning

confidence: 99%

“…In this context, it must be considered that heterogeneous parameter distributions may provide the image of a rather homogeneous aquifer with calibrated hydraulic parameters representing a mean value. This is of particular relevance for cross-hole pumping tests, since the sign of the sensitivity varies in space, and the magnitude and most sensitive regions vary in time (Leven et al 2006). While type curve analysis is an established method for pumping test evaluation, the authors are not aware of publications which consider spatial and temporal sensitivities for a comprehensive interpretation.…”

Section: Introductionmentioning

confidence: 99%

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Hydraulic characterisation of the Stuttgart formation at the pilot test site for CO2 storage, Ketzin, Germany

Wiese¹,

Böhner²,

Enachescu³

et al. 2010

International Journal of Greenhouse Gas Control

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The paper presents an approach for the interpretation of hydraulic tests of a CO 2 storage reservoir. The sandstone reservoir is characterised by a fluviatile channel structure embedded in a low-permeability matrix. Pumping tests were carried out in three wells, with simultaneous pressure monitoring in each well. The hydraulic parameters (permeability and storativity) and the boundary configurations were calibrated using three different approaches: (i) parameter calibration and type curve interpretation for single-hole tests, (ii) calibration of the entire build-up phase for cross-hole tests, and (iii) calibration of the initial pressure response for cross-hole pumping tests. In addition, the arrival time of the pressure response was determined and provides additional information about the pathways of hydraulic connection. The measured pumping test permeabilities of the formation were much lower than those measured on the cores, which is very unusual. The pumping test permeabilities are mainly between 50 and 100 millidarcy (mD), while core samples show a mean aquifer permeability of 500 to 1,100 mD. Based on this it was concluded that some kind of continuous low permeability structure exists, which was supported by core material. Three possible aquifer configurations were considered. The first and second were derived from traditional pumping test analysis and were conceptualised using flow boundaries. Each of the analyses provides a different result. A method was developed in which these differences were resolved by interpreting the pressure response with respect to its spatial and temporal sensitivity. This solution lead to a third configuration which was mainly based on spatially-variable permeabilities. Taking into account the pumping test results, the geological background and the behaviour of injected CO 2 , we consider only the third configuration to be realistic. The results are in good agreement with modelled CO 2 arrival times and pressure history.

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Section: Instrumentationmentioning

confidence: 96%

Section: Instrumentationmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hydraulic characterisation of the Stuttgart formation at the pilot test site for CO2 storage, Ketzin, Germany

Wiese¹,

Böhner²,

Enachescu³

et al. 2010

International Journal of Greenhouse Gas Control

View full text Add to dashboard Cite

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Resolution analysis of tomographic slug test head data: Two‐dimensional radial case

Paradis

Gloaguen

Lefebvre

et al. 2015

Water Resources Research

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Hydraulic tomography inverse problems, which are solved to estimate aquifer hydraulic properties between wells, are known to be ill-conditioned and a priori information is often added to regularize numerical inversion of head data. Because both head data and a priori information have effects on the inversed solution, assessing the meaningful information contained in head data alone is required to ensure comprehensive interpretation of inverse solutions, whether they are regularized or not. This study thus aims to assess the amount of information contained in tomographic slug tests head data to resolve heterogeneity in K h , K v /K h , and S s . Therefore, a resolution analysis based on truncated singular value decomposition of the sensitivity matrix with a noise level representative of field measurements is applied using synthetic data reflecting a known littoral aquifer. As an approximation of the hydraulic behavior of a real aquifer system, synthetic tomographic experiments and associated sensitivity matrices are generated using a radial flow model accounting for wellbore storage to simulate slug tests in a plane encompassing a stressed well and an observation well. Although fine-scale resolution of heterogeneities is limited by the diffusive nature of the groundwater flow equations, inversion of tomographic slug tests head data holds the potential to uniquely resolve coarse-scale heterogeneity in K h , K v /K h , and S s , as inscribed in the resolution matrix. This implies that tomographic head data can provide key information on aquifer heterogeneity and anisotropy, but that fine-scale information must be supplied by a priori information to obtain finer details.

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Analytical sensitivity analysis of transient groundwater flow in a bounded model domain using the adjoint method

Lü

Vesselinov

2015

Water Resources Research

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Sensitivity analyses are an important component of any modeling exercise. We have developed an analytical methodology based on the adjoint method to compute sensitivities of a state variable (hydraulic head) to model parameters (hydraulic conductivity and storage coefficient) for transient groundwater flow in a confined and randomly heterogeneous aquifer under ambient and pumping conditions. For a special case of two-dimensional rectangular domains, these sensitivities are represented in terms of the problem configuration (the domain size, boundary configuration, medium properties, pumping schedules and rates, and observation locations and times), and there is no need to actually solve the adjoint equations. As an example, we present analyses of the obtained solution for typical groundwater flow conditions. Analytical solutions allow us to calculate sensitivities efficiently, which can be useful for model-based analyses such as parameter estimation, data-worth evaluation, and optimal experimental design related to sampling frequency and locations of observation wells. The analytical approach is not limited to groundwater applications but can be extended to any other mathematical problem with similar governing equations and under similar conceptual conditions.

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What information can we get from pumping tests?-comparing pumping test configurations using sensitivity coefficients

Cited by 58 publications

References 40 publications

Hydraulic characterisation of the Stuttgart formation at the pilot test site for CO2 storage, Ketzin, Germany

Hydraulic characterisation of the Stuttgart formation at the pilot test site for CO2 storage, Ketzin, Germany

Resolution analysis of tomographic slug test head data: Two‐dimensional radial case

Analytical sensitivity analysis of transient groundwater flow in a bounded model domain using the adjoint method

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