Assessing borehole geophysical data by simulating borehole flow in - PowerPoint PPT Presentation

Assessing borehole geophysical data by simulating borehole flow in fractured bedrock aquifers Andrew S. Reeve and Joseph Sawdey University of Maine, Dept. of Earth Sciences asreeve@maine.edu Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

What is a fractured bedrock aquifer? Aquifer Subsurface unit that yields a significant amount of water to a well. Fractures Breaks in rock that groundwater flows through Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Assess fractured bedrock aquifer with: rock core surface geophysics borehole geophysics Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Assess fractured bedrock aquifer with: rock core surface geophysics borehole geophysics Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Caliper Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Heat-Pulse Flow Meter Model Flow Data: Results: Transmissivity Far-field Head Purpose: Water Supply Contaminant Transport Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Borehole Data (Jonesboro, Maine) Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Borehole Flow Model Presented in Paillet (1998) Maximize value of data Quantify hydraulic parameters for discrete zones Model not widely Soil/Sediment available Bedrock Trail and error Equilibrium level methodology Level after Based on superposed removing 'slug' Far-Field Head 1 sequence of slug tests Integral equation for recovery Cooper, Bredehoeft, Far-Field Head 2 Papadopulos (1967) Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Borehole Flow Model Recovery (length) 0 0 Andrew S. Reeve and Joseph Sawdey Slug 3 Slug 2 Slug 1 S l u g T e s t Time R e s Simulating borehole flow p o n s e

Borehole Flow Model Recovery (length) Slug 1 e s n o p s Slug 2 e R t s e T g u Fracture Response l S to Slug 3 Fracture Response to Slug 1 Slug 3 0 0 Time Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Borehole Flow Model Recovery (length) Slug 1 e s n o p s Slug 2 e R t s e T g u Fracture Response l S to Slug 3 Fracture Response to Slug 1 Slug 3 Fracture Response 0 to Response to Slug 1 0 Time Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Simplified Program Structure Assign Hydraulic Numerically Integrate Data to Borehole (scipy.integrate.quadpack.quad) Interpolate Recovery vs. Time (scipy.interpolate.UnivariateSpline) Loop over time Loop over fractures Sum fracture responses to slugs using Interpolation Update well water level Return flow in well between fractures Borehole Flow Data Compare with measured Data (scipy.optimize.leastsq) Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Validation Q(Analytic)=0.5000 gpm Q(Dt=0.5)=0.4999 gpm Q(Dt=2.0)=0.4999 gpm Andrew S. Reeve and Joseph Sawdey Simulating borehole flow

Borehole Flow Model Fit Head Diff.=0.096 m Head Diff.=-0.038 m Head Diff.=-0.047 m Andrew S. Reeve and Joseph Sawdey Simulating borehole flow