SU598007A1 - Method of measuring attenuation coefficient at acoustic well logging - Google Patents

Description

(54) METHOD FOR MEASURING THE DETERMINATION RATIO AT THE LKUGTCHCH WITHOUT OF THE WELLS OF SATURATORS, which leads to an error in the measurement of the attenuation coefficient in the acoustic logging of the squash. The aim of the invention is to increase the accuracy of measurement. The goal is achieved by measuring in a known method, based on the amplitude and frequency of the formation of different signal lengths of acoustic transducers that have passed a different path length, from a voltage-slowing voltage pulse on the storage capacitor of the detector of the near signal relative to the radiator receiver, they form a sequence of pulses exponentially falling back edge, which is fed to an amplitude comparator, and compared with slow ccrp during the clock with the voltage of the ciirHa.noB detector and then the KOfvinap.iTopa pulses are selected using the coincidence scheme and B; They will match the capacitors of the detector signal detector to the near and far publishers, which will then be recorded using an instrument for measuring average current. Compounding the duration of a cycle time is a p01: SP {e}, it obtains measurement accuracy due to mutual errors with a positive and negative sign. FIG. 1 shows an example implementation of the method; YAP FIG. 2 - voltage plots on the circuit elements The replication circuit is connected with the system of fire amplitudes of signals that came to 11, respectively, from the near Hundred from one receiver to the receiver and to the long-range transmitters of the three-channel lemma probe of the well device. In the jToii system, each of the emitters is excited at certain intervals of time, corresponding to a cycle duration T. , and the shift between the MOMcuTavui excitation of the one and the other radiator corresponds to half of the tact's duration. Accumulator A detector of the screen detector of the near-emitter at the beginning of each clock cycle is charged with several nepBbiNoi signal inputs, and then slowly discharged, and the voltage on it decreases, decreasing by the time of the next clock signal by 10-15%, due to the need to preserve the resolution of the equipment. Thus, on the storage capacitor of the detector of the screens of the near-emitter, there is a slowly varying pattern within the clock and then above U. The voltage of the storage capacitor of the detector of the far-emitter U has a similar form due to a temporary shift in the excitation of the emitters and this voltage is 180 degrees (half the time duration) relative to the voltage U.f. The main elements of the circuit implementation method are the circuit formaking 1, the quantizing generator 2, the amplitude comparator 3, the selector 4. using the circuit 1 for which a slowly varying voltage is applied from the main capacitor of the signal emitter detector and rectangular pulses 0 of the quantizing generator 2, is obtained in each cycle of the sequence of pulses of 4C exponentially 1 m back edge. The formation circuit contains a parallel RL circuit and a controllable transistor switch, the state of which, closed or open, is determined by the polarity of the pulses of the quantizing oscillator 2. When a negative pulse arrives and the J of the quantizing oscillator 2 is opened, the RC circuit capacitor charges to the value of the voltage corresponding to the given moment of time {J, when a positive pulse arrives, the key is closed and the capacitor exponentially discharges through the loop resistor to 0. The discharge time is determined by n hundred xoy discharge loop time T. The impulse U formed in this way, with an exponentially falling falling front and a peak coinciding with the curve and, is repeated with each subsequent period of operation of the quantizing oscillator 2, and only about 100 times (n) during the operating cycle of the radiator. A self-oscillating multivibrator, implemented on an operational amplifier, is used as a quantizing generator 2. Sequence of pulses U. obtained using the circuit form {1, serves w comparator 3, where it is compared in amplitude with a slowly varying voltage U 2 on the capacitor capacitor of the detector of the far-emitter signal fed to the second input of the col- orator 3, which was completed at the operational amplifier, at the moment of the amplitude of the fronts pulses and circuits forcing 1 with a voltage Ug at the output of the coltarator 3, jumps occur. Biased changes, for example, in each cycle, form a sequence of rectangular pulses Uy, the fronts of which correspond to the trigger times of the comparator 3. The pulses and J are passed through a selector 4 made in the coincidence circuit where the pulses and the quantizing generator 2 are simultaneously applied. to the selector of positive pulses U, and U ,. At the selector output, rectangular positive Hbie pulses U 5, the beginning and end of each of which correspond to moments in the belt, when the falling exponent of each nz pulses C, have a value of U. and U, respectively. The intensity of the pulses obtained at the specified amplitude-interval As is known, the conversion is determined by the expression T RC -En n pulses during each clock cycle of the emitters. The average current can be defined as 1j.p - m-RC s g151 where m is a constantT1P1a value depending on the number of impulses and shtyleyyusti that and parameters of the coincidence circuit. Since U. and J are proportional to the amplitudes of the signals from the near and far radiators, the damping coefficient can be defined as

L K1.r

where K is the proportionality coefficient.

As can be seen from the expression for i,, in Teiejme of each clock cycle, the average currents from each of the n pulses are output and the output of the coincidence circuit. Since the voltages U and U are shifted by 180 °, during the first half of the operation cycle of the near and emitter, when the accumulator capacitor of the detector of the signal of the near radiator is less discharged than the accumulator capacitor of the detector of the signal of the far emitter, and, therefore, an error with a negative sign in the definition of a. In the second half of the cycle, when the accumulative capacitor of the far-emitter detector siphls appears to be less discharged, there is an error with a positive sign. Since the pressure on the capacitors during the cycle of operation of each of the emitters varies according to the same law and the number of pulses in each half of the cycle is one-sided (the possible error in 1 pulse at 100 pulses per cycle can be neglected), The negative errors S f f S5 are equal and mutually compensate for 2 2. .V2., (B. TS-A1 A i

Here Td Gd are the fast bits of the detectors of 3 signals of the near and far emitters, respectively.

1so, in the indications of the regasgrator carote your own, fixing the average value of the current from the pulses Ug, there will be an elimination error, JQ

associated with a time shift in the measurement channels.

The use of the proposed method for measuring the attenuation coefficient of a trpc acoustic wellbore curve ensures 1t significant reductions in instrumental error and, as a result, increased reliability of information: about rocks intersected by a well.

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Claims (3)

1. US Patent No. 3270316, cl. 340-18, 1966. 2. US patent number 3251029, cl. 340-18 1966. 3. Equipment for logging oil and gas wells. VNIIOENG, M., 1973, p. 50-53. J2 / f register / pair Phi. П-Л-П-П-ПГШ sh 3 SSSBSEWT l - П il П П П П n Ftfif