GRAVITY MONITORING OF A WATER-FLOODED ZONE IN AREAL SWEEP

摘要

Methods, systems, and devices for characterizing a water-flooded zone in an earth formation resulting from injection of water to the formation through an injector well borehole intersecting the formation. The method includes estimating horizontal elongation of the water-flooded zone using a gravity field change in the injector well borehole. Estimating horizontal elongation may include predicting a gravity field change for each of a plurality of model water-flooded zones for the borehole, wherein each model water-flooded zone is an elliptical cylinder having finite height and semi-axes; and fitting the gravity field change to one of the predicted gravity field changes corresponding to one of the plurality of elliptical cylinder model water-flooded zones. The gravity field change may comprise a difference between a first estimated gravity field in the injector well borehole before injection and a second estimated gravity field in the injector well borehole after injection.