SU779963A1 - Device for acoustic well-logging - Google Patents

Description

(54) DEVICE FOR ACOUSTIC WELLS OF WELLS

I

The invention also relates to the field of geophysical methods for investigating wells, in particular, to acoustic logging.

With acoustic logging time

The propagation of elastic vibrations in mountainous rocks is determined by the PS nepBbnvi by the inputs of the useful signal, whose amplitude exceeds a certain level.

An acoustic logging device is known in which the acquisition time of the useful signal in the auxiliary storage unit 1 is memorized. During the reception of the next parcel, the newly measured time is compared with the stored entry time of the previous parcel in the memory. If the absolute difference between the two signals is less than the preselected noporxjBoro value, for example, the period of the emitted signal, then the measurement

the last signal is considered true; is transmitted to the auxiliary storage unit and the measurement drive. However, this device only passively ascertains cases of jumps to the phase with a threshold device. The scheme does not make a timely analysis of the reliability of the acoustic signal extraction 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, a decrease in the measurement accuracy.

The closest to this technical solution is an acoustic logging device, in which the principle of synchronous accumulation and separation of the useful signal is carried out against the background of interference by comparing the time of occurrence of all the triggering pulses of the threshold device to the received signal of the last emission period with the triggering pulses of the threshold device

The previous emission period is 1.

 A symptom of detecting the first arrivals of a useful signal against the background of interference is the simultaneous arrival of the above device pulses with a threshold device, extended to allow for a possible change in the arrival time of the useful signal from one radiation period to another (vertical velocity gradient in the well). The coincidence circuit cso signal gives a command to roll over the measuring trigger, when this closes the process of measuring the arrival time of the useful signal 5. However, a coincidence signal is generated in different ways, depending on the observed velocity gradient. In the case when the radiation period is one to the last 20, the propagation time of the sound in the rock increases, the coincidence circuit generates a signal at the moment of appearance of the pulse of the threshold device of the last radiation period. The corresponding 25th extended pulse of the previous period and the emission prepares a coincidence circuit for operation and only confirms that it is not a noise that is recorded, but a useful signal. In the case of recalling

From one radiation period to another, the propagation time of the sound decreases; at the output of the coincidence circuit, a signal is produced at the time of the appearance of the pulse of the preceding radiation period. Thus, the device in this case has an ionicity, which will increase with an increase in the number of accumulated signals of different periods, radiation. In addition to Tcffo, when changing the arrival time to an increase in the useful signal's time, the device does not measure the time in the first phase in which the useful signal 45 is received with a minimum propagation time in the rock, which reduces the measurement accuracy. Since decreasing the propagation time of the sound triggers the measuring trigger when the pulse is output from the auxiliary storage unit, in order to obtain diagrams of sufficient accuracy (ttl μs), a memory unit with a write-read cycle time less than 55 T. μs is required. With a standard probe length of 1.5 m sviKocTb memory while maintaining accurate recording i i μs will be 1024 bits. Implementation of small-sized

a block of memory with the specified parameters is a rather complicated task.

The aim of the invention is to improve the accuracy of measuring the time interval during the registration of the kinematic characteristics of the rocks of the well section.

This goal is achieved by the fact that in an acoustic logging device, a power amplifier, a synchronizer, a threshold device, a memory unit, expanders between the match pattern and a measuring trigger, an intermediate trigger is inserted, the unit installation input of which is connected to the extender output connected to the threshold device, and the output of the intermediate trigger is with the input of the measuring zero.

The drawing shows a block diagram of a device for measuring interval time.

The interval time measurement device comprises an amplifier 1 connected to a synchronizer 2 and a threshold device 3, a memory unit 4, expanders 5.6, a matching circuit 7, an intermediate trigger 8, a measuring trigger 9. The output of the synchronizer 2 is connected to the input of the memory unit 4 and the input, the setting of the measuring trigger unit 9. The output of the threshold device 3 is connected to the input of the memory unit 4, and through the expander 5 to the input of the coincidence circuit 7 and the installation input zero of the intermediate trigger 8. The output of the memory unit 4 is connected via the expander 6 to another The input is the coincidence circuit input 7, the output of which is connected to the installation input of the unit of intermediate trigger 8. The output of intermediate trigger 8 is connected to the installation input of the zero- ing trigger.

The device works in the following way.

The acoustic logging signal is fed through amplifier I to the input of syn, chronizer 2 and input to threshold device 3. Synchronizer 2 generates a pulse corresponding to the radiation moment, which sets the unit in measurement trigger 9 and clears the operation of memory block 4. Trigger pulses of threshold device 3 the signal is fed to the input of the expander 5 and to the input of the memory unit 4. Simultaneously, from the output of the memory unit 4 to the input of the expander 6, the threshold device triggers to the signal of the previous period and radiation. The extended pulses from the extenders 5,6 are fed to the coincidence circuit 7.. .

The front of the pulse from the output of the coincidence circuit 7 sets the unit to an intermediate one, but does not command the end of the process to measure the sound propagation time in the measuring trigger 9. The tilting out of the measuring trigger 9 is produced by dropping the pulse of the intermediate trigger 8. The zeroing of the intermediate trigger 8 is always performed from the fall to the pulse of the threshold device 3, expanded in the expander 5. In this case, the measured true time of propagation. the path of sound in the rock for each channel (T T-) is added to the constant-20 time -t p for which the pulse of the threshold device .3 is being expanded in the expander 5. However,

calculating the interval time A T the specified time tp is excluded, 25

Thus, the break of the measuring trigger in the device is always carried out by the triggering pulses of the threshold device 3 to the signal of the last period of radiation, which excludes the possible 30

Ability to skip the values of the propagation time of the useful signal when changing the arrival time to increasing the arrival time. This allows an increase in the number of parcels for a simultaneous 35 accumulation of up to three or more;

p registration accuracy. The pulses coming from the memory unit 4 and giving information about the triggering of the threshold device to the signal in the previous period of radiation, now have only to confirm that this threshold pulse in the last period of radiation to the useful signal a no noise. The accuracy of 45 occurrences in time of the pulses from the output of the memory unit 4. the device no longer has

Claims (2)

1.Patent of France M 2171957, cl. Q01 V 1/40, published 1975. 2. USSR author's certificate According to the application number 2524421, CL G O1 1 / 4O D. 977 (prototype). S.