Borehole ultrasonic piezoelectric transducer and borehole ultrasonic logging instrument

Abstract

The present invention provides a borehole ultrasonic piezoelectric transducer and a borehole ultrasonic logging instrument, wherein the borehole ultrasonic piezoelectric transducer includes a casing, and the casing is provided with a positive electrical connector and a negative electrical connector; The piezoelectric composite sheet arranged in the housing, the two ends of the piezoelectric composite sheet are respectively provided with a metal positive electrode and a metal negative electrode, the metal positive electrode is connected to the positive electrical connector, and the metal negative electrode Connect the negative electrode connector; the matching layer group arranged on the metal positive electrode side of the piezoelectric composite sheet; the backing damping block arranged on the metal negative electrode side of the piezoelectric composite sheet, the back The lining damping block absorbs the ultrasonic energy radiated backward by the piezoelectric composite sheet. The borehole ultrasonic logging tool includes the borehole ultrasonic piezoelectric transducer. The invention reduces the acoustic impedance of the vibrating chip by the piezoelectric composite material, and solves the impedance mismatch between the downhole transducer and the propagation medium with a multi-layer matching layer structure.

Description

technical field [0001] The invention relates to a borehole wall ultrasonic piezoelectric transducer and a borehole wall ultrasonic logging instrument, belonging to the field of air drilling. Background technique [0002] Air drilling is an underbalanced drilling technology that uses compressed air as a circulating medium. It has many advantages such as high ROP, short well construction period, reduction or avoidance of formation leakage and reservoir damage. It is the most potential drilling in the 21st century. one of the technologies. In recent years, domestic air drilling technology has developed rapidly. For example, more than ten wells of air hammer gas drilling have been carried out in western oilfields in my country, with a cumulative footage of more than 10,000 meters. However, in the process of high-efficiency rock-breaking drilling, air drilling has brought complicated situations such as serious irregularity of wellbore cross-section, increased wellbore roughness,...

AI Technical Summary

Problems solved by technology

Therefore, the ultrasonic piezoelectric transducers used for the detection and imaging of borehole shape and borehole wall characteristics in the existing wireline / logging while drilling cannot be used in the air drilling environment due to impedance mismatch, which greatly limits the downhole ultrasonic imaging The scope of application of logging technology

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