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Simulation Assessment of Direct Push Injection Logging for High-Resolution Aquifer Characterization
Gaisheng Liu1, Robert C Borden2, James J Butler1
1Kansas Geological Survey, University of Kansas, Lawrence, KS, 66047.
Ground Water
|September 5, 2018
Summary
Direct push injection logging (DPIL) accurately determines hydraulic conductivity (K) in permeable soils. In less permeable soils, specific storage (Ss) influences K estimation, and slow probe advancement minimizes errors.
Area of Science:
- Environmental science
- Hydrogeology
- Geotechnical engineering
Background:
- Direct push injection logging (DPIL) is a common method for measuring vertical hydraulic conductivity (K) profiles in environmental investigations.
- A lack of rigorous analysis exists regarding DPIL's physical processes and performance under varied hydrogeological and operational conditions.
Purpose of the Study:
- To analyze the physical processes governing DPIL.
- To evaluate DPIL performance across different hydrogeological settings and operational parameters using numerical simulations.
Main Methods:
- Numerical simulations were employed to model DPIL processes.
- The study analyzed the relationship between injection rate, pressure, hydraulic conductivity (K), and specific storage (Ss).
Main Results:
- The ratio of injection rate to pressure directly estimates K for K > 10^-6 m/s.
- For K < 10^-6 m/s and Ss > 10^-3 /m, Ss significantly impacts K estimation, requiring additional data.
- Probe advancement significantly affects pressure readings in formations with low K and Ss, especially in fine-grained materials.
Conclusions:
- DPIL is effective for estimating K in moderate to high hydraulic conductivity formations with low specific storage.
- Accurate K estimation in low-permeability materials necessitates considering specific storage and minimizing probe advancement speed (e.g., 0.5 cm/s) to reduce pore water pressure artifacts.
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