Research of tidal water level amplitude and phase and application to causation analysis of well water level changes

The theory of the amplitude and phase shift of tidal well water-level variation in well-aquifer-aquiclude system (WAAS) is introduced to study hydraulic flow among the well, fractures and micro-fractures (porosity) in the well-fracture-micro-crack fracture (porosity) system (WFMS). While analyzing the tide induced pore pressure and the hydraulic flow process in WFMS, the main factors affecting amplitude and phase shift in WFMS were drawn up. The amplitude ratio A and phase α₂ of the tide water-lever caused by hydraulic flow between the well and fractures vary with the same tendency as equivalent transmissivity (T). The amplitude ratio D and phase α₁ of tidal water-lever caused by hydraulic flow between fracture and micro-crack (porosity) vary in opposite trend with the tidal amplitude ratio (E'/E) between fracture and micro-crack under undrained condition. An analysis table on aquifer deformation is listed in this paper according to the changes of well water level, tidal amplitude and phase ratio. And is used to analyze abnormal causes of water level changes in Dongchuan, Mile and Xichangchuan 03 three wells.