A method comprising: determining a measurement plan comprising one or more acoustic measurements (604, 608); lowering in a borehole penetrating a subsurface formation a toolstring having one or more phased array modules (200; 324, 326, 328, 502), wherein each phased array module comprises: a plurality of acoustic transducers operable to emit an acoustic excitation signal and receive an echo signal; and a programmable circuit (212,222) configured to set one or more variables of the phased array modules; configuring the one or more phased array modules, wherein configuring the one or more phased array modules includes programming the programmable circuit to set the one or more variables of the one or more phased array modules according to the measurement plan; performing (632, 640) the one or more acoustic measurements of the measurement plan using the configured one or more phased array modules; and characterizing one or more of the formation, a casing disposed in the borehole, and/or an annulus between the casing and the formation, using results of the performed one or more acoustic measurements; the method being characterized in that performing the one or more acoustic measurements comprises: performing a first one of the one or more acoustic measurements while the toolstring is moved in a first trip through a first portion of the borehole, wherein a phased array module utilized for the first acoustic measurement is configured to emit acoustic excitation signals simultaneously at a plurality of azimuths distributed fully around the borehole; the method further comprising: updating the measurement plan by processing results of the first acoustic measurement and changing parameters of one of the acoustic measurements of the measurement plan and/or adding an acoustic measurement to the measurement plan; and performing a second acoustic measurement while the toolstring is moved in a second trip through a second portion of the borehole, wherein the second acoustic measurement is the changed and/or added acoustic measurement, and wherein the first portion of the borehole comprises at least a part of the second portion of the borehole. determining a measurement plan comprising one or more acoustic measurements (604, 608); lowering in a borehole penetrating a subsurface formation a toolstring having one or more phased array modules (200; 324, 326, 328, 502), wherein each phased array module comprises: a plurality of acoustic transducers operable to emit an acoustic excitation signal and receive an echo signal; and a programmable circuit (212,222) configured to set one or more variables of the phased array modules; a plurality of acoustic transducers operable to emit an acoustic excitation signal and receive an echo signal; and a programmable circuit (212,222) configured to set one or more variables of the phased array modules; configuring the one or more phased array modules, wherein configuring the one or more phased array modules includes programming the programmable circuit to set the one or more variables of the one or more phased array modules according to the measurement plan; performing (632, 640) the one or more acoustic measurements of the measurement plan using the configured one or more phased array modules; and characterizing one or more of the formation, a casing disposed in the borehole, and/or an annulus between the casing and the formation, using results of the performed one or more acoustic measurements; the method being characterized in that performing the one or more acoustic measurements comprises: performing a first one of the one or more acoustic measurements while the toolstring is moved in a first trip through a first portion of the borehole, wherein a phased array module utilized for the first acoustic measurement is configured to emit acoustic excitation signals simultaneously at a plurality of azimuths distributed fully around the borehole; the method further comprising: updating the measurement plan by processing results of the first acoustic measurement and changing parameters of one of the acoustic measurements of the measurement plan and/or adding an acoustic measurement to the measurement plan; and performing a second acoustic measurement while the toolstring is moved in a second trip through a second portion of the borehole, wherein the second acoustic measurement is the changed and/or added acoustic measurement, and wherein the first portion of the borehole comprises at least a part of the second portion of the borehole. updating the measurement plan by processing results of the first acoustic measurement and changing parameters of one of the acoustic measurements of the measurement plan and/or adding an acoustic measurement to the measurement plan; and performing a second acoustic measurement while the toolstring is moved in a second trip through a second portion of the borehole, wherein the second acoustic measurement is the changed and/or added acoustic measurement, and wherein the first portion of the borehole comprises at least a part of the second portion of the borehole.