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Among the various geophysical well logging techniques, acoustic logging can work at adequate frequency，it features good resolution and detection distance. The directional radiation of acoustic power based on acoustic phased arc array transmitter that can significantly improve the signal to noise ratio of acoustic logging detector is a key technology for a multidimensional array acoustic logging tool. The phased arc array transmitter comprises several transducer stations, which arranges several transducers around a circle. Because of confined space and the finite capacity of power supply, the sharp increment of transducers results in a challenge to excitation circuits. In this paper, three excitation methods based on the transformer, half-bridge, and full-bridge ware proposed, and then these methods ware studied by experiment in a water pool. In the experiment, a transducer that was excited by the three excitation circuit creates an acoustic wave in a water pool. Meanwhile, a hydrophone that was 2m away from the transducer received the acoustic signal. The amplitude of the received acoustic signal and the power consumption of the excitation circuit ware recorded to evaluate the efficiency of the excitation circuit. By analyzing the structure of the three excitation cir-cuit and the experimental results, we can learn the excitation method based on the half-bridge features outstanding advantage in miniaturization and efficiency. And the excitation methods based on the half-bridge also has good simplicity on excitation frequency adjustment. Moreover, a 32-channel excitation circuit based on half-bridge for phased arc array transmitter was designed. The excitation circuit was divided into two parts that ware separately installed into two small pressure-bearing cartridges. These two pressure-bearing cartridges are mounted on both sides of the transducer array with 32 transducers to form an active downhole acoustic phased arc array transmitter. The active downhole acoustic phased arc array transmitter was measured in the water pool. Experimental results are conforming to theoretical simulation. This proves the good feasibility of the excitation method. The active downhole acoustic phased arc array transmitter had been tested in the field for five times. The highest temperature in the field test is 160℃ and the maximum pressure is 140MPa. The field test proves the excitation circuit has good feasibility and practicability.
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