Heave Induced Aquifer Water Level Fluctuations

摘要

Abnormal water level fluctuations in Quaternary aquifers have been evident since early 1994 in one part of the Cold Lake Field undergoing Cyclic Steam Stimulations in the Clearwater, while in other areas no response to steaming operations have been observed. Recent high resolution seismic of the Quaternary has demonstrated a complicated geology with ice thrusting events leading to isolation of parts of the aquifers into small pockets. Coupling this geological observation with poro-elastic modelling of the effects of Clearwater dilation caused by steaming and subsequent recompaction by production has led to an explanation of the observed water level fluctuations. The mechanism causing water level rises is compression of a pocket of aquifer sand due to Clearwater dilation as a result of steam injection. For aquifer pockets directly over the steam injection location, aquifer dilation, rather than compression, results from the Clearwater dilation, causing water levels to fall. Aquifer sands that are extensive allow pressure equilibration and no apparent water level changes due to nearby Clearwater dilation. Net injection to the Clearwater appears to be a significant correlative indicator of Clearwater dilation, but sensitivity of the aquifer water level change to net injection decreases with increasing steam cycle number. First principle numericalrnsimulations coupling fluid flow and formation stress-strain behaviour support the relationships developed.