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A Multi-Modes LWD Sonic Transmitter

IP.com Disclosure Number: IPCOM000202692D
Publication Date: 2010-Dec-22
Document File: 5 page(s) / 175K

Publishing Venue

The IP.com Prior Art Database

Abstract

We propose a new type of borehole acoustic transmitter that can generate strong acoustic impulses for LWD sonic logging. In addition, it is capable of generating different acoustic modes. The acoustic impulse is generated when a hammer strikes an acoustic resonator mounted outside the tool collar. The resonator enhances the acoustic radiations through the borehole fluid and coupled the acoustic energies to the formation. The principle is based on firing a magnetic actuation coil that moves a plunger connecting to at least one mechanical hammer by a guided cable using pulley to change the cable moving direction. The cable reduces the acoustic coupling toward the tool body while hammer striking the resonator and therefore, reduces tool arrivals. In this design, the electrical pulsing of the coil can be adjusted to control the hammer striking speed. In addition, there are built-in retracting elements to return the hammer to its origin after each firing. The length and diameter of the resonator determine the dominating frequency of the source and therefore can be adjusted depending on the characteristics one wants its source to achieve. This impulse source has a very wide bandwidth and can easily be pressure compensated and operate at extreme pressure and temperature environments as encountered in LWD environment.

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