Monitoring fluid stored in a subterranean formation

Abstract

A fluid monitoring system includes at least one injection wellbore formed from a terranean surface into a subterranean formation; a fluid injection assembly configured to circulate a fluid through the at least one injection wellbore and into the subterranean formation; at least one monitor wellbore formed from the terranean surface into or near the subterranean formation, where the at least one monitor wellbore is separated from the at least one injection wellbore by the subterranean formation; at least one acoustic energy source positioned in the at least one monitor wellbore and configured to emit acoustic energy from the at least one monitor wellbore into the subterranean formation; and at least one acoustic energy receiver positioned in the at least one monitor wellbore and configured to receive acoustic energy reflected from the fluid circulated into the subterranean formation to the at least one acoustic energy receiver.

Dependencies are inferred from the claim text.