LWD sonic logging tool works and technical performance
Acoustic logging while drilling equipment working principle and structure.
From right to left by the upper short section of the electronic circuit portion of the sound source, omnidirectional sound source, acoustic isolators, an array of receivers, the receiver electronics section, a lower nipple like.
Its working principle is: the sound source is located in the drill collar in an upper portion of the emitter at an optimum frequency energy emitted acoustic pulse to the formation around the wells, the array is received by the receiver during the broadcast signal along the borehole wall and travels downward in the surrounding formation, reception after signal conversion, the system first with embedded technology advanced, the received acoustic analog signal into a digital signal, and using the finite element method such as a digital signal into an acoustic time (data) value. Finally, the original acoustic waveform data and acoustic waveform data pre-stored in the cache memory or in a well-designed drilling fluid pulse telemetry real time transmission to the surface [9].
The main technical performance of the instrument are described below:
(1) the use of a full set of cylindrical piezoelectric crystal to the transmitter of the instrument, providing 360 ° coverage of the wellbore and surrounding formation, the sound source may be within the frequency range 10-18000Hz FM, and can be transmitted to the monopole and dipole
(2) by 4 full receiver array to the receiver array 6, a pitch of 228.4mm. Receiver array sound source in a straight line, to achieve a multi-pole excitation radial excitation.
(3) with insulation to avoid acoustic wave propagating directly from the transmitter to the receiver of the instrument. APX sound insulation tape is designed to 3m, which features a plurality of frequency regulation, signal insulation capacity of up to -40dB, an excellent sound insulation effect.
A sound source (4) having a receiver of the instrument's transmission frequency optimization function, which has received a lot of several bands lower than the instrument itself, can significantly reduce the interference of the receiver and the drill pipe connection. In the case where the transmission source turned off, the main instrument measured signal noise below 5kHz of PDC bits.
Acceleration (5) for noise detection count of three accelerometers mounted on a receiver for capturing the flow of drilling noise and vibration generated when drilling the drill string, and then extracted by optimizing the formation signal filtering techniques.
(6) the first quadrupole wave technology uses quadrupole wave transmission technology, compatible signal transmitting and receiving monopole and dipole. This allows multiple combinations of instruments to transmit different formations, different measurement mode, there are more practical.
