Laboratory simulation on acoustic well-logging with phased array transmitter

Two small scale acoustic phased arrays with 4 elements are designed and set up in our laboratory and experiments are made on them. It is found that both the directivity and the radiation lobe width of the arrays can be regulated by changing the fire delay time between the neighbor elements. The results measured are in good agreement with those calculated. Then, assigning the phased arrays as acoustic transmitters and hydrophone as receiver, the small scale acoustic well-logging simulations are carried out both on an aluminium model well and on a concrete model well. The experimental results show that, by increasing the fire delay time between the neighbor elements, the steered angle of the arrays become larger and larger, and the generation conditions of refracted compressional wave and refracted shear wave are satisfied successively, while the refracted compressional wave, refracted shear wave and Stoneley wave are strengthened separately. Therefore, by choosing the distance between neighbor elements of an array and the acoustic frequency appropriately, the main lobe of the arrays can be widened to cover the first critical angle of refracted compressional wave in all kinds of formation, which makes it possible to apply phased array acoustic well-logging in any formation continuously without regulating directivity of the phased array.