SU1203450A1 - Apparatus for synchronizing acoustic logging equipment - Google Patents

Description

one

This invention relates to acoustic well survey methods.

The purpose of the invention is to increase the accuracy of measuring the kinematic parameters of elastic waves by reducing the level of interference in the information channel.

Figure 4.1 shows a block diagram of a synchronization device; figure 2 is a timing diagram illustrating its work.

In the ground control unit 1, the synchronization device consists of a synchronization unit 2 and a control unit 3, which includes a generator of 4 clock pulses and a driver of 5 alternating starting pulses. Block 2 synchronization, and contains the discriminator 6 zero and two formers 7 and 8 synchronization pulses.

The ground control unit I is connected by a geophysical cable 9 to a downhole device 10, which includes a selector 11 trigger pulses, a transmitter unit 12 for a three-element probe emitter, a discriminator 13 zero and a trigger pulse generator 14.

The device works as follows.

When the ground panel 1 is turned on and the power is supplied to the inputs of the 4 clock pulses of the control unit 3, the discriminator 6 zero of the synchronization unit 2 and the discriminator 13 zero, the supply network voltage of the downhole tool 10 enters (Fig. 2, curve 15). The discriminators 6 and 13 form identical pulse sequences, the pulse fronts of which correspond in time to the zero crossing of the supply network of the downhole tool 10 (Fig. 2, curve 16).

The clock pulse generator 4 periodically, at predetermined time intervals, produces, with reference to the power supply network zero, two sequences of pulse signals (FIG. 2, curves 17 and 18), which, using the first and second inputs, start the driver 5 different polarity starting pulses (FIG. .one

Formed and power-amplified opposite polarity pulses are mixed and alternately cycle 03450

It is received from the driver 5 through the phantom power supply circuit to the input of the downhole tool 10 (Fig. 2, curve 19). In selector II

5, per channel, they are separated per channel.

If the input of the selector 11 receives a starting impulse of negative polarity - a sign of the first

10 channels, in this case, a normalized pulse appears at its first output, connected with the driver 14 for the trigger pulses. As the main element of the former 14

15 in the simplest case, is a memory element, for example, R, S is a trigger, then it is tilted at the K input. At the output of the driver 14, a trigger pulse appears logic O (figure 2, curve 20). The discriminators 6 and 13, respectively, of the ground control unit 1 and the downhole tool 10, form a sequence of pulses directly from the network voltage.

25 coal form. In time, the leading edges of the output pulses of the discriminators 6 and 13 correspond to the moments of zero crossing of the sinusoidal voltage of the network (Fig. 2, curves

30 15 and 16). Therefore, after tilting, after a time equal to one half-period of network voltage, the output impulse of the discriminator 13 short-triggers, the shaper 14 returns

 in the initial state. At the output of the driver 14, logical 1 appears again (FIG. 2, curve 20). At the same time, a positive differential is allocated by the input device of the radiator bumper block 12.

The emitter of the three-element acoustic probe is excited, the base of which is formed by two pressure receivers. Acoustic oscillations are emitted into the well, which, having passed through the test medium, are fed to the receivers of the first and second channels of the probe. But in this cycle, only the receiver of the first (near) channel is connected to the amplifier-transmitting to the path. Therefore, amplification and transmission via the information channel to the ground control unit I of the signal from the first receiver of the probe occurs.

At the same time, in the ground panel 1, the output impulse of the first control channel of the generator 4 clock pulses

50

55

pulses (negative polarity starting pulse generation channel) is fed to the input of a synchronization pulse generator 7, where it is memorized, for example, by a KS trigger (Fig. 2, curve 21). The KS trigger of the synchronizer pulse 7 returns to its initial state The operation is performed by the output signal of the discriminator 6 zero, at a time equal to that of the shaper 14 of the starting pulses of the downhole tool 10, the half-period of the supply voltage. Since the discriminator 6 of the ground control unit 1 and the discriminator 13 of the downhole tool 10 operate synchronously and in phase, the logical 1 at the output of the former 7 of the ground control unit 1 appears simultaneously with the logical 1 at the output of the former 14 start pulses of the downhole tool 10. Therefore, a positive difference at the output of the former 7, it is used as a synchronization pulse of the first channel of Sync.1, from the moment of its appearance in the computing device of the console 1 the time of propagation of elastic waves in the first to analogue t (from the transmitter probe of the downhole tool through the test medium to the near receiver).

Measurement of time i, is performed while recording the arrival of the first instances of the information signal. After this, the tact of measuring the time of propagation of elastic waves through the second channel of the probe ij is performed (radiator — medium under study).

In this case, a control signal appears in the second output of the 4 clock pulse generator (Fig. 2, curve 18), which is already memorized by the synchronization pulse shaper 8, performed similarly to the shaper 7. Logic O appears at the output of the shaper 8 (Fig. 2 , curve 22). At the same time, an output starting pulse of positive polarity of the former 5 of the control unit 3 of the ground control station 1 via geophysical cable 9 starts the second channel of the selector 11 of the downhole tool 10 Output pulse of the second channel

with ju T5 20 25 o

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five

0

five

of the selector Yu, the RiS trigger of driver 14 is triggered by the start-up ICOB, which, as in the previous cycle, returns to its initial state through a pulse of discriminator 13 after a period of time equal to the half-period of the network voltage.

At the output of the driver 14, a trigger pulse appears logical 1 (FIG. 2, curve 20), with a positive differential which, through block 12, excites the probe emitter.

The process of measuring the time of propagation of elastic waves through the second channel t begins.

A synchronization pulse Sync 2, formed from a positive differential at the output of the imaging unit 8 of the synchronization unit 2 of the ground control unit 1, when the output of the discriminator 6 zero arrives at its second input (figure 2, curve 22), is taken as a starting point. At the same time, the shaper 7 of the first synchronization channel is also scanned at the second input, but its connection 1sh does not change.

After excitation of the transmitter probe of the downhole tool 10, after a time depending on the spacing of the transmitter — the long-range receiver and the characteristics of the surrounding medium — an information signal is sent from the long-range receiver along the amplifying and transmitting path to the ground control panel 1. device console 1 is the measurement of time i. j and the calculation of the formula

A -iz-i, (1)

where ii and ij are the propagation times of the elastic waves according to the first (near) and second (far) channels of the probe, respectively;

D-i is the interval time value.

This ends one measurement cycle. The process described below is repeated.

In the process of conducting research, alternate connection to the measuring and transmitting path of the receiving

The NIKS of the probe of the downhole tool 10 is performed by the output pulses of the selector 11.

Thus, the principle of operation of the synchronization device is based on the temporal reference to the same phase of the mains voltage of the beginning of the measuring cycle in two parts of the equipment (the surface control panel and the downhole device connected by a cable line.

In the synchronization device, the starting pulses formed in the ground control unit and the excitation moment of the radiator are rigidly connected to the zero crossing of the sinusoidal voltage of the downhole power supply network. Moreover, the excitation of the emitter is delayed with respect to the starting pulse at the same time — one half-period of the supply voltage. This allows, without transmitting from the downhole tool to the ground console, the pulse of the moment of excitation of the radiator to form in the synchronization unit the signals that are the starting point of the propagation time of elastic waves along the first and second instrumentation measurement channels.

The advantage of the proposed synchronization device for acoustic logging equipment, the well tool of which contains tre 3034506

An elemental probe with a measuring base formed by two pressure receivers, as compared to a known synchronization device, for an apparatus with a three-element probe containing two emitters and a pressure receiver, consists in a higher accuracy of measuring the interval time, since the error in fixing the transition moment supply voltage through zero in the ground control and the moment of starting the radiator of the downhole tool for both channels of measuring the propagation time of elastic waves one and

The same is, therefore, when calculating the interval time Ai by the formula (1), the error caused by phase shifts in the transmission of power from the surface console to the downhole tool via a geophysical cable and the time delay in the transmitter's excitation channel is zero.

20

mains, missing,

When using probes with a length of 0.5-1.2 m, the signal-to-noise ratio in a high-speed section is improved: the measurement accuracy of the main kinematic parameter of the longitudinal refracted waves - the interval time is increased.

The technical and economic effect is achieved by increasing the reliability and quality of the obtained geophysical information.

Compiled by V.Krutin Editor A.Sabo Tehred d.BOYKO

Order 8411/48 Circulation 747 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch ShSh Patent, Uzhgorod, Proektna St., 4

FIG. g

Proofreader L.Patai

Claims (1)

ACOUSTIC LOGGING DEVICE SYNCHRONIZATION DEVICE, consisting of a borehole and a ground part interconnected by a geophysical cable, to which also a downhole tool power network is connected, while the ground part contains a synchronization unit and a control unit consisting of a clock pulse generator and a generator of multipolar trigger pulses, moreover, the input of the clock generator is connected to the power supply network of the downhole tool, both outputs of the clock generator are connected to the shapers once non-polar trigger pulses, the output of which is connected to the geophysical cable, and the downhole part consists of a trigger pulse selector and a three-element probe emitter excitation block connected to the geophysical cable, characterized in that, in order to increase the accuracy of measuring the kinematic parameters of elastic waves by reducing the level interference in the information communication channel in the ground part of the synchronization unit is made in the form of a discriminator of zero and two formers of synchronization pulses, the first inputs of which coot— g are identical with the first and second outputs of the clock pulse generator of the control unit, the second inputs of the synchronization pulse shapers are combined and connected to the power supply of the downhole tool through a zero discriminator, and a zero discriminator and a start pulse shaper are introduced into the borehole part, the first and second inputs of which connected respectively to the first and second outputs of the trigger pulse selector, the third input of the trigger pulse shaper is connected to the input of the trigger pulse selector, and the output the driver pulse generator is connected to the input of the excitation unit of the emitter of the three-element probe. SU. „1203450