Use of minor borehole obstructions as seismic sources

Abstract

An acoustic system and method for monitoring a hydrocarbon reservoir. Wellbore tube wave energy may be created by natural or ambient sources or tube waves may be excited intentionally. Wellbore tube wave energy is converted to seismic body wave energy at minor borehole obstructions or irregularities. Each obstruction or discontinuity position along the borehole has an associated unique waveform source coda that may be measured for processing the body waves radiated into the earth formation surrounding the well bore. A plurality of sensors detects the radiated seismic energy after the seismic body wave energy has transited intervening earth formations. The system may be employed for permanent monitoring of mineral resources and resource management. Measurements of reservoir characteristics may be acquired at many different times over the productive life of a reservoir. A time-lapse profile may be created that is representative of the temporal and areal changes in the petrophysical characteristics and mineral content or distribution of the intervening earth formation.

Dependencies are inferred from the claim text.