An experimental study on azimuthal reception characteristics of acoustic well-logging transducers based on phased-arc arrays

Abstract

New technologies and methodologies of acoustic logging must be developed to facilitate the exploration and development of heterogeneous and anisotropic reservoirs. Thus, design, fabrication, and performance testing of new transducers have drawn considerable attention. We evaluated a new type of acoustic receiver based on the phased-arc array. An acoustic phased-arc array receiver is composed of numerous piezoelectric elements uniformly distributed on a circumference. Several adjacent elements form a phased-arc subarray. Phased-arc subarrays can output several waveform traces, which comprise the waveforms of azimuthal reception. The directivity of the element and phased-arc subarray is crucial to azimuthal reception of the receiver. Related experiments were done to verify the performance of the transducer. Test results revealed that the angle width of the main lobe of a phased-arc subarray was substantially narrower than that of any single element of the phased-arc array, and the amplitude difference corresponding to the incident direction measured by the phased-arc array was more obvious than that by independent elements. The direction of incident acoustic waves to the receiver was easily determined with the signal amplitudes of the phased-arc subarrays. The direction of the incident waves determined by subarray was in accordance with the real direction of the incident waves and better than that by independent elements. The advantages of azimuthal reception would significantly improve the azimuthal resolution and the signal-to-noise ratio of acoustic logging data. Azimuthal reception may be also important for evaluation of anisotropy and circumferential heterogeneity.