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

A method for localizing acoustic energy within a wellbore traversing a subterranean formation, the method comprising:

• providing a downhole tool that can be conveyed within the wellbore, the tool having a transmitter array comprising a plurality of transmitter elements, wherein each transmitter element can be configured to emit an acoustic borehole guided mode signal at variable amplitude and variable time delay, wherein the variable amplitude is controlled by an amplitude factor assigned to the given transmitter element, and wherein the variable time delay is controlled by a time delay assigned to the given transmitter element;
• and
• assigning a set of amplitude factors and time delays to the transmitter elements of the transmitter array to control operation of the transmitter elements of the transmitter array such that the transmitter elements produce a focused acoustic beam at a desired zone-of-interest, wherein the focused acoustic beam is formed at the desired zone-of-interest in the wellbore by combination of acoustic borehole guided mode signals transmitted by the transmitter elements of the transmitter array controlled according to the set of amplitude factors and time delays assigned to the transmitter elements of the transmitter array, wherein:
• the set of amplitude factors and time delays for the transmitter elements of the transmitter array are determined based upon a model that relates wellbore coordinates to amplitude factors and time delays for the transmitter elements of the transmitter array that will produce focused acoustic beams at different zones in the wellbore.