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The transition problem in pumped aquifers
Author(s) -
Johnson Mark L.,
Brutsaert Willem F.
Publication year - 1979
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr015i005p01266
Subject(s) - drawdown (hydrology) , aquifer , compressibility , mechanics , flow (mathematics) , boundary value problem , finite difference method , multiphase flow , nonlinear system , geology , phase transition , geotechnical engineering , water table , mathematics , physics , groundwater , thermodynamics , mathematical analysis , quantum mechanics
Confined aquifers may develop water table conditions near the well bore and under prolonged pumping stresses this condition may spread to the recharge area. This situation is defined as the transition problem. The physics of the transition problem is examined by modeling well flow with a finite difference computer simulator. The computer simulator is based on two‐dimensional, two‐phase flow and takes into consideration formation compressibility, fluid (air and water) compressibility, solubility of air in water and a seepage face boundary condition at the well bore. A fully implicit finite difference scheme is used to solve the nonlinear flow equations by employing a modified Newton iteration process. The results obtained in this study agree with field data. Current analytical approaches seem to overestimate drawdown levels in time. The analysis shows that the transition problem is a unique combination of confined and unconfined flow. Gravity flow near the well bore appears to dominate the total flow pattern and affects drawdown at farther distances from the well bore where flow is radial. It was also shown that partially penetrating wells behave much like fully penetrating wells at certain radial distances from the well bore.