273 Hydrogeology I: Physical Hydrogeology

Wednesday, 3 November 2010
1:30 PM - 5:30 PM
Room 402

FLASH – A PROGRAM FOR FLOW-LOG ANALYSIS OF SINGLE HOLES

Paper number: 273-7
Program: Technical Sessions
Time: 3:00 PM – 3:15 PM

Authors

Abstract

Historically, borehole-flow logs have been used to delineate flow zones under ambient conditions or to determine zone contributions under stressed conditions. More recently, flow logs have been analyzed to estimate flow-zone transmissivity and far-field heads. This type of quantitative analysis requires collection of logs and water levels under both ambient and stressed conditions and use of an analytical or numerical model.

The USGS computer program, FLASH (Flow Log Analysis for Single Holes), provides an easy-to-use utility for the quantitative analysis of flow logs collected in single boreholes. The code is based on a multi-layer, analytical solution for steady-state radial flow to a single borehole. FLASH provides a simple graphical user interface (GUI) for calibration of an analytical borehole-flow model and for estimation of flow-zone transmissivities and far-field heads. Flow zones can be discrete fractures, fracture zones, or aquifer layers. FLASH is embedded within a Microsoft Excel spreadsheet and uses Visual Basic for Applications (VBA) routines to invoke the Excel solver for automated parameter estimation.