A general numerical model for water level response to harmonic disturbances in aquifers considering wellbore effects

Stiff, Smooth, and Solid? Complex Fracture Hydraulics' Imprint on Oscillatory Hydraulic Testing

“…Field experimental setups may also inadvertently lead to an apparent period‐dependence in returned hydraulic parameter estimates. For example, non‐Darcian flow or borehole storage effects on test analysis may lead to errors in test interpretation (e.g., Quinn et al., 2011; Xing et al., 2022). Patterson and Cardiff (2023) used simple analyses and analytical models to explore the potential of non‐Darcian flow and borehole storage as potential mechanisms contributing to the period‐dependent flow parameters returned during their field experiments and showed that these experimental design effects do not fully account for the apparent period‐dependence in effective hydraulic parameter estimates.…”

Water level response to harmonic disturbances in confined aquifers: modeling, global sensitivity, and applications

“…In contrast, oscillatory pumping tests stand out with their adjustable periods, which can be artificially controlled from a few seconds to several minutes. Previous studies observed a diminishing impact on water lever responses when source period exceeds hundreds seconds (Cooper et al 1965, Xing et al 2022. Therefore, in this study, the main focus is on shortperiod (less than hundreds of seconds) sources to analyze their influence on water level responses.…”

“…A disturbance source, represented by 𝐴𝐴 0 and 𝑇𝑇 0 , exhibits amplitude attenuation and phase delay during the pressure diffusion process in aquifers, attributed to the damping effect of the porous medium (Black andKipp 1981, Cardiff et al 2013). When considering wellbore effects, such as the water column inertia and wellbore storage, water level amplitude (𝐴𝐴 𝑤𝑤𝑤𝑤 ) can be either attenuated, remain equivalent, or amplified, and the phase (𝑃𝑃 𝑤𝑤𝑤𝑤 ) might be delayed, stay in-phase, or even advanced (Cooper et al 1965, Liu et al 1989, Xing et al 2022. Despite these insights gathered from previous studies, it is necessary to clarify the following practical issues: (1) determining the conditions under which the monitoring well reacts to aquifer disturbances, (2) understanding the potential response mechanisms of water level amplitude and phase, and (3) identifying the impact of wellbore effects on water level responses.…”

“…Periodical aquifer disturbance sources can mechanistically be divided into two categories, the pressure diffusion (PD) source and the volumetric strain (VS) source (Xing et al 2022). PD sources cause water level oscillations through the process of pore pressure diffusion in the aquifer, e.g., ocean tides and oscillatory pumping tests.…”

“…However, due to the wellbore effect, it remains controversial whether the well water level response can truly reflect the pore pressure changes in the aquifer (Xing et al, 2022). Based on the developed general well-aquifer model, a global sensitivity analysis of the associated nine parameters on water level responses is conducted.…”