Guided mode beamforming for probing open-hole and cased-hole well environments

A downhole tool that uses acoustic energy to probe a wellbore traversing a subterranean formation, the downhole tool comprising:

• at least one transmitter configured to emit borehole guided mode acoustic signals that propagate in the wellbore;
• a receiver array comprising a plurality of receiver elements, wherein each receiver element of the receiver array is configured to detect acoustic waveforms that result from propagation of the acoustic borehole guided mode signals in the wellbore and apply variable amplification and a variable time delay to the detected acoustic waveforms, wherein the variable amplification is controlled by an amplification factor assigned to the given receiver element, and wherein the variable time delay is controlled by a time delay assigned to the given receiver element;
• and
• a controller that configures the at least one transmitter to emit the borehole guided mode acoustic signals that propagate in the wellbore and assigns a set of amplification factors and time delays to the receiver elements of the receiver array and combines signals resulting from the application of the variable amplification and the variable time delay to the detected acoustic waveforms such that sensitivity of the receiver elements of the receiver array is focused at a desired zone-of-interest in the wellbore corresponding to the set of amplification factors and time delays assigned to the receiver elements of the receiver array.