SU750411A1 - Device for acoustical logging of wells - Google Patents

Description

The invention relates to geophysical well survey methods, in particular, to acoustic logging. In acoustic logging (AK), the time when elastic waves propagate in rocks is determined by the first inputs of the useful signal, the amplitude of which exceeds a certain level. In order to improve the noise immunity of the AK equipment, the accumulation of the received signal in the random access memory is used, and after the accumulation is completed, the total signal is recorded on the magnetic tape for measuring the time and amplitude parameters. In this case, the useful signal is summed in phase, while the noise is randomly summed . However, the efficiency of accumulation of the useful signal decreases with. the appearance of a time shift of the first entry of the useful signal in adjacent premises relative to each other. The time shift of the first arrivals is observed when the diameter of the well, the speed of sound over the depth of the well, and depends on the logging speed. A device for acoustic well logging is known in which the effect of the time shift on the effect of synchronous accumulation of the useful signal is reduced by introducing delayed feedback to the ground recorder of the amplifier, the value of which is recorded depending on the acoustic wave propagation time obtained by the recorder l. The presence of an amplifier delayed by the period of sending feedback ensures the accumulation process, and a change in the magnitude of the feedback in the range from 0 to 1 proportional to the change in the recorded speed of sound ensures the optimum number of accumulations. Closest to the invention. This is an acoustic logging device that stores the useful signal arrival time of the previous package in auxiliary memory 2. When the signal of the next package is received, the newly measured time is compared with the stored time of the previous one. parcels If the absolute difference between the two signals is less than the preselected threshold value, such as the period of the emitted acoustic signal, then the measurement is considered true, and the last signal is transferred to the auxiliary storage unit and measuring storage. However, device 23 only passively states cases of a jump to the nopSoroBHM phase by the device. The scheme does not produce a timely analysis of the accuracy of the acoustic signal, and only later, based on the results of the measurements and comparisons, a false measurement is rejected, which leads to a loss of information and, consequently, to a decrease in the accuracy of measurements.

The aim of the invention is to improve the measurement accuracy of the device.

This is achieved by the fact that in a known acoustic logging device comprising a downhole tool consisting of an emitter, a receiver, an electronic unit, and ground equipment including a synchronizer, an amplifier, a radiation pulse extraction circuit, a measuring trigger, a threshold device, a counting pulse generator, key, pulse counter, measuring drive, auxiliary memory block with control circuit, the synchronizer output connected to the zero pulse counter input, output of the impuser allocation circuit The radiation is connected to the installation input of the trigger unit, and the output of the trigger with the second key input, two pulse extenders and a matching circuit are entered, the input of one of the expanders directly connected to the output of the threshold device, and the other the extender outputs are connected via a coincidence circuit with the zero input of the measuring trigger.

The drawing shows a block diagram of the proposed acoustic logging device.

An acoustic well logging device comprises a downhole tool consisting of a receiver 1, radiated. the driver 2, the electronic unit 3 and the ground equipment consisting of the synchronizer 4, the amplifier 5, the injection pulse b of the pulse emitter signal, the downhole tool, the measuring trigger 7, the threshold device 8, the series of counting pulse generator 9, the key 10, the pulse counter 11, as well as the measuring storage unit 12, the auxiliary storage unit 13 with the control circuit 14, the expanders 15, 16 and the coincidence circuit 17. The counting pulse generator 9 is connected via a control circuit 14 to the auxiliary storage unit and 13, performed, for example, in a shift register. In this case, the control circuit 14

It can be performed i-a ring; modulo counter, equal to the number of cells of the shift register. The output of the cells of the counter 11 is connected to the inputs of the sensing accumulator 12. The signal output of the downhole tool is connected through an amplifier 5 to a threshold device 8 and to a radiation pulse extraction circuit b and then to the unit input of a measuring trigger unit 7, the output of which is connected to one of the inputs of the key 10. The input of the extension 15 is connected directly to the output of the threshold device 8, and the input of the extender 16 is connected via an auxiliary storage unit 13. The outputs of the extenders 15 and 16 are connected via a matching circuit -17 to the input of the zero setting KSR Control trigger 7 and write enable input measuring 12.Rasshiriteli accumulator 15 and 16 are, / for example, a monostable multivibrator, with a small reduction time.

The device works as follows.

The pulses from the synchronizer 4 output synchronize the operation of the radiator 2 of the downhole tool, and the counter 11 is reset. Receiver 1 converts the acoustic signal transmitted through the loop into an electrical signal, which, after amplification in the electronic unit 3, is transmitted through the cable to the ground equipment. Through the amplifier 5, the signal, generally consisting of radiation pulses, interference and the desired signal, is fed to the radiation pulse extraction circuit 6, the radiation pulse emission circuit 6 generates a pulse corresponding to the radiation moment from the received signal. trigger 7. trigger 7 opens the key 10, which transmits pulses from the generator of counting pulses 9 to the input of counter 11, thereby starting the propagation time of the acoustic signal-In the borehole. At the same time, the pulse produced by the extraction circuit gives permission for the passage of pulses from the generator of counting pulses 9 through the control circuit 14 to the clock input of the auxiliary storage unit 13, providing information stored in it to the time of emission of the signal.

The signal from amplifier 5 is also fed to. the input of the threshold device 8, which forms, when the received signal exceeds a certain level, a sequence of short pulses, ow. This sequence of pulses is fed to the input of the expander 15 and simultaneously to the input of the auxiliary storage unit 13.

Claims (2)

When a 13th pulse of the threshold / Device 8 pulse appears at the input of the memory unit, a unit is recorded in the first cell of the shift register of the memory unit 13. The newly recorded unit, as well as the previously recorded information, is moved through the register by means of pulses of the generator of counting pulses 9, fed through the control circuit 14 to the clock input of the register. Consequently, simultaneously with recording the pulses of the threshold device from the received signal of the last parcel from the output of the memory unit 13, a sequence of pulses of the threshold device from the signal of the previous one going to the expander 16 is given. In expanders 15 and 16 the duration of each incoming pulse increases up to 4-12 µs, depending on the expected time shift of the useful signal between the sendings. The sequence of extended pulses corresponding to both the input signal and the signal from the thresholds of the previous and last parcel is fed to the input of the matching circuit 17. The pulses of the threshold device corresponding to the disturbance are randomly distributed in time, and the arrangement of the pulses corresponding to the useful signal coincides with the send ki to the parcel by increasing their duration in expanders 15 and 16. Therefore, the appearance of a pulse at the output of the coincidence circuit 17 indicates that the useful signal arrives at la This pulse triggers the measuring trigger 7, closes the key 10 and the counter code 11, corresponding to the arrival time of the useful signal, is transferred to the measuring storage 12. Thus, the decision to allocate the first entry of the useful signal in the proposed device occurs on the basis of a comparison in time of the pulses of different parcels. . Due to this feature, the proposed device responds inertia-free to changes in the arrival time of the useful signal. The decision on the arrival time of the useful signal corresponds to the time of arrival of the useful signal of the last parcel with increasing time from the parcel to the parcel of the time being measured, and not the average arrival time of the useful signal of the analyzed number of parcels. Due to the fact that the pulses of the threshold device 8 are further analyzed with the purpose of distributing the useful signal against the background of impulses from interference, the threshold level is made more sensitive, which reduces the likelihood of a jump to phase and improves the measurement accuracy. Since, in this device, the auxiliary storage unit is connected directly to the threshold device, as a result of which, in the memory unit, all information about the threshold device operation is recorded on the received signal, both on the useful signal and on the noise. This feature allows selection of the useful signal against the background of interference when comparing the signal of the previous parcel with the newly received signal of the last parcel, which increases the noise immunity and, ultimately, the measurement accuracy. The invention The device for acoustic well logging, comprising a downhole tool consisting of a radiator, a receiver, an electronic unit and ground equipment including a synchronizer, an amplifier, a threshold device, a radiation pulse extraction circuit, a measuring trigger, a counting pulse generator, a pulse counter, an auxiliary memory unit with a control circuit, a measuring storage device, the synchronizer output connected to the pulse counter zero input, the output of the pulse extraction circuit The radiation is connected to the installation input of the trigger unit, and the output of the trigger with the second key input is different from the fact that, in order to improve the measurement accuracy of the device, two pulse extenders and a coincidence circuit are introduced, and the input of one of the expanders is directly connected to the output threshold the device, and the input of the other through the auxiliary memory block, while the outputs of the expanders are connected via a coincidence circuit with the input of the zero setting of the measuring trigger. Sources of information taken into account during the examination 1. USSR author's certificate No. 399815, cl. G 01 V 1/40, 1972. 2. The patent of France No. 2171957, cl. 6 01 V 1/40, 1975. (Prototype).