| Abstract: | Conventional interpretation of flow logs assumes that hydraulic conductivity is directly proportional to flow change with depth. However, well construction can significantly alter the expected relation between changes in fluid velocity and hydraulic conductivity. Strong hydraulic conductivity contrasts between lithologic intervals can be masked in continuously screened wells. Alternating intervals of screen and blank casing also can greatly complicate the relation between flow and hydraulic properties. More permeable units are not necessarily associated with rapid fluid-velocity increases. Thin, highly permeable units can be misinterpreted as thick and less permeable intervals or not identified at all. These conditions compromise standard flow-log interpretation because vertical flow fields are induced near the wellbore.
AnalyzeHOLE, an integrated wellbore analysis tool for simulating flow and transport in wells and aquifer systems, provides a better alternative for simulating and evaluating complex well-aquifer system interaction. A pumping well and adjacent aquifer system are simulated with an axisymmetric, radial geometry in a two-dimensional MODFLOW model. Hydraulic conductivities are distributed by depth and estimated with PEST by minimizing squared differences between simulated and measured flows and drawdowns. Hydraulic conductivity can vary within a lithology but variance is limited with regularization. Transmissivity of the simulated system also can be constrained to estimates from single-well, pumping tests. Water-quality changes in the pumping well are simulated with simple mixing models between zones of differing water quality. These zones are differentiated by backtracking thousands of particles from the well screens with MODPATH. An Excel spreadsheet is used to interface the various components of AnalyzeHOLE by (1) creating model input files, (2) executing MODFLOW, MODPATH, PEST, and supporting FORTRAN routines, and (3) importing and graphically displaying pertinent results. |
| Genre: | USGS Numbered Series |
| ProdID: | 97898 |
| Citation Author: | Halford, Keith |
| Citation Contributing Office: | U.S. Geological Survey |
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| Citation Edition: | - |
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| Citation Language: | ENGLISH |
| Citation Larger Work Title: | Chapter 2 of Section F, Groundwater, Book 4, Hydrologic Analysis and Interpretation |
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| Citation No Pagination: | N |
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| Citation Online Only Flag: | N |
| Citation Phsyical Description: | Report: viii, 47 p.; Application Files (ZIP) |
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| Citation Publisher: | U.S. Geological Survey |
| Citation Series: | Techniques and Methods |
| Citation Series Code: | TM |
| Citation Series Number: | 4-F2 |
| Citation Search Results Text: | AnalyzeHOLE - An Integrated Wellbore Flow Analysis Tool; 2009; TM; 4-F2; Chapter 2 of Section F, Groundwater, Book 4, Hydrologic Analysis and Interpretation; Halford, Keith |
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| Citation Year: | 2009 |
| Type: | citation/reference |
| Text: | AnalyzeHOLE - An Integrated Wellbore Flow Analysis Tool; 2009; TM; 4-F2; Chapter 2 of Section F, Groundwater, Book 4, Hydrologic Analysis and Interpretation; Halford, Keith |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/tm_4_f2.jpg |
| URL (INDEX PAGE): | http://pubs.usgs.gov/tm/tm4f2/ |
| Date Other: | Sat, 3 Oct 2009 00:00 -0500 |
| Publisher: | U.S. Geological Survey |
