Geophones for recording acoustic waves in water

Title : Geophones for recording acoustic waves in water

Abstract:

In the modern concept, the geophone is an electrodynamic converter. The geophone has a mechanical resonance at frequency f0. In practice, a characteristic area is used after resonance with a linear frequency dependence (f1) limited to a frequency of 110-120 Hz. The amplitude-frequency characteristic of a piezoelectric transducer has a quadratic dependence of the amplitude on the frequency (f2). But the disadvantage of the piezoelectric transducer is its high impedance, which requires the mandatory use of a preamplifier with a high input impedance. The current requirements for increasing the resolution of seismic exploration of oil and gas by amplitude and frequency have served as a pretext for developing a new geophone converter similar to an electrodynamic geophone, but which uses a section before mechanical resonance with a cubic amplitude-frequency dependence (f3) as the performance characteristic. This allowed solving the problems inherent in traditional geophones, namely: expand the range of recorded frequencies from 1 to 1000 Hz, increasing the upper limit of the frequency of received signals to 1 (5) kHz. In parentheses, the calculated data for the fifth generation geophone are given. The new transducer was developed on the basis of the magnetoelastic effect in a ferromagnet with a crystalline structure (iron-aluminum alloy), which allowed the construction of a vector sensor with a single inertial mass and three electric windings. Modern hydrophones use mainly piezoelectric effects of crystalline and ceramic materials with high sensitivity to pressure. But the large output impedance of the piezoelectric transducer requires a special preamplifier with a high input impedance. The hydrophone, unlike a geophone with an inert mass, is a scalar device. To determine the direction of arrival of the acoustic signal, and this is one of the main tasks of the device, it is necessary to create special antennas of large dimensions. With the use of a new transducer, a hydrophone with an inertial system can be constructed that will measure three components of the wave velocity vector (pressure gradient) of the acoustic wave in water.

Keywords: Geophone, Hydrophone, Scalar Measurement, Vector Measurement, High Resolution, Vibrating Speed, Gradient Pressure

Biography:

Askold Belyakov was born in 1932. He holds higher technical (1950-1956), economic (1963-1964), postgraduate (1968-1970), and political (1978-1979) degrees, a Candidate of Technical Sciences degree (1971), and the title of Senior Research Fellow (1975). In 1956, he graduated from the Moscow Power Engineering Institute (MEI) with a qualification as a thermal engineer. After graduation, he worked in the field of automation in the mining and metallurgical industries. From 1960 to 1968, he headed the automation laboratory at the Zaporozhstal plant in the Ukrainian SSR. In 1968, he entered full-time postgraduate studies at the Moscow Institute of Chemical Engineering (MIKhM), which he completed ahead of schedule in 1970 by defending his candidate's dissertation. He was then hired through a competitive process as the head of the automation laboratory at the All-Union Research Institute of the Chemical Industry. In 1975, he was awarded the title of Senior Research Fellow. In 1980, he was hired through a competitive process as a Senior Research Fellow at the Institute of Physics of the USSR Academy of Sciences, and in 1997 he was appointed to the position of Leading Research Fellow. He retired in 2016. The total number of publications is 160, including 43 author's certificates for inventions in the USSR and patents in the Russian Federation. Since 2013, I have been living in San Francisco, California, USA.