Two‐dimensional characterization of hydraulic heterogeneity by multiple pumping tests

Li, Wei; Englert, Andreas; Cirpka, Olaf A.; Vanderborght, Jan; Vereecken, Harry

doi:10.1029/2006wr005333

Cited by 74 publications

(82 citation statements)

References 44 publications

(96 reference statements)

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“…The high storage coefficients may be an indication of contact with another aquifer layer and thus a water source between the wells, or they may be the result of vertical cross-flow in the observation wells. In this case, however, they are probably the result of overfitting due to unresolved spatial heterogeneity (Li et al 2007). The permeability between Ktzi 200 and Ktzi 201 shows values between 166 and 431 mD, which is significantly greater than the mean aquifer permeability.…”

Section: Cross-hole Observationsmentioning

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: Cross-hole Observationsmentioning

confidence: 99%

“…Several methods exist for the identification of spatial structures and variability (e.g. Vasco et al 2000, Vasco et al 2001, Li et al 2007, Wiese and Nützmann 2008. However, these approaches were designed to analyse large datasets and do not permit the evaluation of single-hole tests.…”

Section: Instrumentationmentioning

confidence: 99%

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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show abstract

“…A second group of methods estimates a single best solution that captures some of the details at smaller scales, namely those which are important for groundwater flow and transport predictions, and also estimates an uncertainty associated with the prediction [e.g., Hernandez et al, 2003;Vermeulen et al, 2004;Tonkin and Doherty, 2005;Tonkin et al, 2007]. Often, the calibration focuses on the uncertain hydraulic conductivities, but sometimes also other parameters like the storativities [Hendricks Franssen et al, 1999;Li et al, 2007] or recharge rate [Hendricks Franssen et al, 2004 are subject to calibration. Only rarely, like in the Representer Method [Bennett, 1992;Valstar, 2001] the uncertainty of the model itself is considered.…”

Section: Motivationmentioning

confidence: 99%

Real‐time groundwater flow modeling with the Ensemble Kalman Filter: Joint estimation of states and parameters and the filter inbreeding problem

Franssen

Kinzelbach

2008

Water Resources Research

260

303

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[1] Real-time groundwater flow modeling with filter methods is interesting for dynamical groundwater flow systems, for which measurement data in real-time are available. The Ensemble Kalman Filter (EnKF) approach is used here to update states together with parameters by adopting an augmented state vector approach. The performance of EnKF is investigated in a synthetic study with a two-dimensional transient groundwater flow model where (1) only the recharge rate is spatiotemporally variable, (2) only transmissivity is spatially variable with s lnT 2 = 1.0 or (3) with s lnT 2 = 2.7, and (4) both recharge rate and transmissivity are uncertain (a combination of (1) and (3)). The performance of EnKF for simultaneous state and parameter estimation in saturated groundwater flow problems is investigated in dependence of the number of stochastic realizations, the updating frequency and updating intensity of log-transmissivity, the amount of measurements in space and time, and the method (iterative versus noniterative EnKF), among others. Satisfactory results were also obtained if both transmissivity and recharge rate were uncertain. However, it was found that filter inbreeding is much more severe if hydraulic heads and transmissivities are jointly updated than if only hydraulic heads are updated. The filter inbreeding problem was investigated in more detail and could be strongly reduced with help of a damping parameter, which limits the intensity of the perturbation of the log-transmissivity field. An additional reduction of filter inbreeding could be achieved by combining two measures: (1) inflating the elements of the predicted state covariance matrix on the basis of a comparison between the model uncertainty and the observed errors at the measurement points and (2) starting the flow simulations with a very large number of realizations and then sampling the desired number of realizations after one simulation time step by minimizing the differences between the local cpdfs (and bivariate cpdfs) of hydraulic head for the large ensemble and the corresponding cpdfs for the reduced ensemble. The two measures, which cause very limited CPU costs, allowed making 100 stochastic realizations for the reproduction of the states as efficient as 200-500 untreated stochastic realizations.

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“…They include numerical studies [e.g., Gottlieb and Dietrich, 1995;Yeh and Liu, 2000;Bohling et al, 2002;Yeh, 2005, 2006;Fienen et al, 2008;Ni and Yeh, 2008;Castagna and Bellin, 2009;Xiang et al, 2009;Liu and Kitanidis, 2011], followed by laboratory sandbox studies [e.g., Liu et al, 2002;Brauchler et al, 2003;Illman et al, 2007;Liu et al, 2007;Illman et al, 2008;Yin and Illman, 2009;Illman et al, 2010;Berg and Illman, 2011a;Illman et al, 2012] and then experimental field studies [e.g. Bohling et al, 2007;Li et al, 2007;Straface et al, 2007;Cardiff et al, 2009;Illman et al, 2009;Berg and Illman, 2011b;Brauchler et al, 2011;Huang et al, 2011]. All these studies have consistently shown that transient HT can identify not only the pattern of the heterogeneous hydraulic conductivity field but also the variation of specific storage.…”

Section: Introductionmentioning

confidence: 99%

Joint interpretation of sequential pumping tests in unconfined aquifers

Mao

Yeh

Wan

et al. 2013

Water Resources Research

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[1] In this study, we developed a stochastic estimator for characterizing the hydraulic heterogeneity in both unsaturated and saturated zones of unconfined aquifers using transient drawdown data from sequential pumping tests. This estimator was built upon the successive linear estimator by Yeh et al. (1996), the simultaneous successive linear estimator by Xiang et al. (2009), and the 3-D finite element program for flow and transport through heterogeneous media by Srivastava and Yeh (1992). The estimator was tested afterward using simulated data sets of sequential pumping tests in a synthetic unconfined aquifer where saturated conductivity, specific storage, saturated water content, and pore-size distribution parameter vary spatially in three dimensions. Test results show that the estimator is able to produce parameter fields that capture the overall 3-D pattern of the true heterogeneous parameter fields. We subsequently validated the estimated parameter fields by assessing their ability to predict drawdowns during an independent pumping test, which was not used during the estimation phase. Results of the validation show that the predicted drawdowns based on the estimated heterogeneous parameter fields are in close agreement with the true drawdowns. In addition, predicted drawdowns based on the parameter fields from the joint interpretation are superior to those based on the parameters estimated from the homogeneous conceptual model. Lastly, while many field experiments are necessary to fully assess the robustness of this estimator and sequential pumping tests, results of this study suggest they are a promising characterization technique for unconfined aquifers.

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Two‐dimensional characterization of hydraulic heterogeneity by multiple pumping tests

Cited by 74 publications

References 44 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

Real‐time groundwater flow modeling with the Ensemble Kalman Filter: Joint estimation of states and parameters and the filter inbreeding problem

Joint interpretation of sequential pumping tests in unconfined aquifers

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