Methods and related systems are described for making measurements at multiple locations in an annular region of a cased sequestration well. A first tool module is positionable within the well and adapted to directly or indirectly measure changing pressure at a first location in the annular region of the well. A pressure change is induced at the first location in the annular region. A second tool module is positionable within the well and adapted to directly or indirectly measure changing pressure at a second location in the annular region. The measured pressure changes at the second location are in response to the induced pressure change at the first location.