Dipole Flow Tracer Test Models for Identifying Skin Properties and Ambient Groundwater Flow Effects

Area of Science:

• Hydrogeology
• Environmental Science
• Geochemistry

Background:

• Dipole flow tests with a tracer (DFTT) are valuable for aquifer characterization.
• Previous studies have not comprehensively addressed skin and ambient groundwater flow (AGF) effects on DFTT.
• Understanding these effects is crucial for accurate solute transport interpretation.

Purpose of the Study:

• To develop a mathematical model for DFTT that incorporates skin and AGF effects.
• To investigate DFTT's potential for identifying skin properties.
• To establish methods for mitigating AGF impacts on DFTT.

Main Methods:

• Development of a mathematical model for DFTT including skin and AGF.
• Analysis of solute transport under various skin conditions and AGF influences.
• Categorization of breakthrough curves (BTCs) based on skin effects.
• Definition of a dimensionless parameter to quantify AGF impact.

Main Results:

• Negative skin enhances tracer transport, acting as a preferential pathway.
• AGF effects on BTCs can be erroneously interpreted as reactions.
• Four distinct BTC types were identified, each indicative of specific skin properties.
• A dimensionless parameter quantifies AGF's overestimation of reaction rates.

Conclusions:

• The developed model accurately accounts for skin and AGF in DFTT.
• DFTT can identify skin properties, and AGF effects can be managed.
• Adjusting field parameters to maintain a dimensionless parameter below 3.7% minimizes reaction rate overestimation to under 50%.