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Techniques and Methods 4–F2

Chapter 2 of
Section F, Groundwater
Book 4, Hydrologic Analysis and Interpretation

AnalyzeHOLE—An Integrated Wellbore Flow Analysis Tool

By Keith Halford

Thumbnail of and link to report PDF (5.5 MB)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.

For additional information contact:
Director, Nevada Water Science Center
U.S. Geological Survey
2730 N. Deer Run Road
Carson City, Nevada 89701
http://nevada.usgs.gov/water/

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Suggested citation:

Halford, Keith, 2009, AnalyzeHOLE—An integrated wellbore flow analysis tool: U.S. Geological Survey Techniques and Methods 4-F2, 46 p.



Contents

Preface

Abstract

Introduction

Approach

Example Applications

Description of AnalyzeHOLE

Installation of AnalyzeHOLE

Data Requirements and Entry

AnalyzeHOLE Commands

Acknowledgments

References Cited

Appendix A. Explanation of User-Specified Variables in AnalyzeHOLE

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