Authors: By YenChen Huang HundDer Yeh
Publish Date: 2012/09/05
Volume: 26, Issue: 14, Pages: 4039-4057
Abstract
Yeh and Chen J Hydro 3423–4283294 2007 integrated a slug test solution for a well having a finitethickness skin with the simulated annealing SA to determine the hydraulic parameters of the skin zone and formation zone Some results obtained in positiveskin scenarios are however not accurate if compared with the target values of the parameters This study first employs the sensitivity and correlation analyses to quantify the relationship between two normalized sensitivities and analyze the resulting errors in parameter estimates It is found that the inaccuracy in parameter estimates can be attributed to following two problems 1 the normalized sensitivities of the skin thickness and hydraulic conductivity are highly correlated and 2 the SA algorithm is very sensitive to roundoff error in wellwaterlevel WWL data A parameter identification approach is thus developed based on the extended Kalman filter EKF coupled with the solution used by Yeh and Chen J Hydro 3423–4283294 2007 to determine the parameters in six positiveskin scenarios where the parameters were not accurately determined before We show that previous two problems can be overcome by the proposed approach because it is designed to account for uncertainties of measurements Moreover the EKF can save 998 and 999 computing time when compared with the results using the SA in analyzing 20 WWL data and 47 WWL data respectivelyResearch leading to this paper has been partially supported by the grant from Taiwan National Science Council under the contract numbers NSC 992221E009062MY3 NSC 1002221E009106 and NSC 1013113E007008 The authors would like to thank the reviewer for his/her constructive comments and suggested modifications
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