SU119627A1 - A device for geophysical measurements in boreholes simultaneously of several parameters - Google Patents

Description

For geophysical measurements in boreholes simultaneously of several parameters, devices are used that operate according to the principle of a low-channel distribution telemetering system. They consist of surface and downhole equipment, including synchronous and in-phase switches. During operation of such devices, not only information pulses are transmitted from downhole equipment, but also a series of service pulses, including standard signal pulses.

A disadvantage of the known devices is that they do not allow the non-contact distribution of the pulses and their amplification.

To eliminate these drawbacks, it is proposed to apply them. magnetically modulated elements, which play the role of switches, in which the distribution of pulses over time is carried out by including phase-changing elements made up of RC-Hen.04eK elements in the excitation windings.

The drawing shows a schematic diagram of the proposed device.

The operation of the device is based on the sequential transmission of short pulses from the well, which characterize the measured values. Each measured value is determined by the difference of the amplitudes of one pair of impulses of different polarity. The separation of pairs of pulses in the receiving equipment according to the recording devices is carried out by the method of coincidence in time of the measured drug pulses and the service arms of the pulses generated at strictly defined times for each of the channels. All necessary temporal shifts at the transmitting and receiving side are established by selecting specific and constant phase relationships. Device power

No. 119627

carried by alternating current with a frequency of about 400 Hz from the generator /; in the downhole equipment current flows through the core cable 2 and through the ground. This current is then converted by the generator 3 into a low frequency current used to supply the electrodes of 4 (or sensors) of the downhole measurement unit.

The potential difference, removed from the measuring electrodes 5 or the measuring resistance of the sensor, is fed to the input of the magnetic modulation element 6, also fed from the generator /. Due to the use of a magnetically soft material such as permallo in the core element and the excitation winding, a strong periodic saturation of the core is created and short-term voltage pulses of various polarities appear at the element output, which are several tens of times shorter than the period of the exciting current. When the voltage between the electrodes 5 is zero, the positive and negative pulses have an equal amplitude. When a voltage appears between the electrodes, the pulses of one polarity, depending on the sign of this voltage, increase, and the impulses of the other polarity decrease. The difference of the amplitudes of these pulses to a certain extent is proportional to the measured voltage. At the output of the magnetic modulation element 6, in addition to these pulses, oscillations with a smaller amplitude arise, due to the nature of the operation of this element. In order to eliminate the error in the measurements associated with these oscillations, the output of element 6 is connected to the amplitude discriminator 7, which passes in line 8 only pulses having an amplitude greater than the cut-off voltage. The voltage to the discriminator 7 is supplied from the rectifier 9, supplied with current from the generator. In the ground equipment, measuring pulses are fed to the input of the phase-rotating element 10. In addition to these pulses, a series of service pulses from the peak transformer are also fed to the input of element 10. When the measuring pulses coincide with the pulses supplied from the peak transformer //, the output of element 10 is a voltage proportional to the difference of amplitudes of positive and negative pulses, which is recorded by the measuring device 12. To create a compensation voltage in the ground equipment in parallel with the device 12, an additional magnetic modulation element 13 is connected, which through the discriminator 14, fed from rectifier 15, sends to the line pulses of different polarity shifted in time relative to eniyu to the pulses supplied from a downhole tool. Thus, in one period of the supply current, two pairs of pulses must be passed along the line to measure each quantity. During the first half period, a positive pulse from the downhole tool and a negative compensation from ground equipment, and during the second half period, a negative pulse from the downhole tool and a positive compensation pulse. In the downhole tool, the compensation pulses are sensed and released by the phase shifter 16 and the peak transformer 17 in the same manner as in the ground equipment.

The voltage from element 16, proportional to the difference in amplitudes of the compensation pulses, is connected in series with the measured voltage and compensates for the latter. The magnitude of the undercompensation is set depending on the gain of the circuit and the expected amplitude of the change in the measured voltage. Power supply of magnetic modulation elements 6 to 13 w. peak transformers L and / 7 are from generator /. Thus, the operation of all elements of the circuit is rigidly synchronized and is independent of the parameters of the cable.

In order to sequentially send pulses to the line from each magnetic modulation element 6, the excitation currents in them are phase shifted. Correspondingly, the pulses arising at the output of the compensation elements 13 are shifted in time. This is achieved by feeding their excitation windings from the phase-rotation elements 10 and 16 containing RC-chains. Peak transmitters // and 17 are configured so that each magnetic modulation element 13 reacts only to the pulses of the corresponding magnetic modulation element 6. This achieves separation of incoming pulses through its own channels and provides measurement and recording of them using a multichannel recording device . In order to eliminate errors in measurement caused by the distortion of information pulses when transmitting them through a cable from a well, a ratiometric measurement scheme in which standard-signal pulses are used as a reference signal can be applied in the proposed device.

Subject invention

Claims (2)

1. A device for geophysical measurements in boreholes of several parameters simultaneously, operating according to the principle of a low-channel distribution telemetering system, consisting of surface and downhole equipment, including synchronous and synphasio operating switches, and in which, in addition to information pulses, a series of service pulses are sent from the well equipment including standard-signal pulses, characterized in that, in order to effect non-contact pulse distribution and amplification of the latter, with eneny guides performs the role of insulation switches magnitomodul elements peak-type, in which the timing pulses is accomplished by including in the field winding fazovraschayuschih elements composed of elements RC-chains. 2. A device according to claim 1, characterized in that, in order to eliminate measurement errors caused by distortion of information pulses when transmitting them through a cable from a well, a ratiometric measurement scheme is applied, in which standard signal pulses are used as a reference signal. - 3 - # 119627