A closed form slug test theory for high permeability aquifers

Area of Science:

• Hydrogeology
• Aquifer Testing

Background:

• Slug tests are crucial for determining aquifer properties.
• Existing analytical models may not fully account for wellbore effects like casing friction.
• Accurate hydraulic conductivity is vital for groundwater resource management.

Purpose of the Study:

• To develop a modified analytical slug test theory incorporating casing friction.
• To provide closed-form equations for pressure and velocity fluctuations.
• To improve the accuracy of hydraulic conductivity estimations in high permeability aquifers.

Main Methods:

• Incorporated a linear estimate of casing friction into existing slug test theory.
• Developed consistent, closed-form equations for free surface, pressure, and velocity fluctuations.
• Linearized turbulent casing shear stress using a characteristic velocity for analytical solutions.

Main Results:

• The modified theory accurately describes pressure fluctuations, accounting for inertia and casing friction.
• Slug tests in the Plymouth-Carver Aquifer yielded a consistent hydraulic conductivity of 1.5 x 10(-3) m/s.
• The new model provides more accurate hydraulic conductivity than the Springer and Gelhar (1991) model, which underestimated values by up to 25%.

Conclusions:

• The inclusion of casing friction significantly improves slug test analysis for high permeability aquifers.
• The developed analytical solution offers a reliable method for determining hydraulic conductivity from transducer data.
• This approach refines aquifer characterization and supports better groundwater management decisions.