SU1255711A1 - Method of measuring temperature gradient downwardly of borehole - Google Patents

Description

This invention relates to well testing using thermometry.

The purpose of the invention is to improve the accuracy of measuring the temperature gradient in the well.

The drawing shows a block diagram of a device for measuring a temperature gradient along a wellbore.

The device contains a downhole thermometer 1 connected by a logging cable 2 to a ground apparatura including an amplifier 3, a shaper 4 rectangular pulses connected to a key 5, a measuring roller 6, a selsyn-sensor 7 cable lengths, a quantization step shaping circuit 8, RS-triggers 9 -12 with separate inputs, keys 13-19, counter-dividers 20 and 21, generator 22 high-frequency pulses, counting triggers 23-25, reversible counters 26 and 27, digital-to-analog converter 28 and recorder 29.

A device for measuring the temperature gradient along the wellbore works as follows.

To directly record the temperature gradient over the wellbore, one should remember the temperature value at a certain point in the well. Then, in the next point, also remember the temperature value and subtract it from the value obtained in the nerve point, etc. If the distance between points at which temperature measurement occurs (quantization step over depth) is constant and equal to a certain LF, then the temperature difference at adjacent measurement points will be proportional to

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The signal from the downhole thermometer 1 in the form of electrical oscillations, the period duration of which is proportional to temperature, goes through cable 2 to amplifier 3, and from it to the shaper 4 square-wave pulses. The formed rectangular pulses, the repetition period of which is proportional to the temperature, arrive at the key 5. When the cable 2 moves, the shaft of the sensor 7 of the sensor 7 rotates along the measuring roller 6, from which the signal to the formation circuit 8 is received. This scheme can be performed, for example, in the form of a disk with holes, which is rotated by the selsyn receiver synchronously with the rotation of the selsyn sensor. At the level of the holes in the disk, the illuminator is installed and opposite the photodetector. When a hole between the illuminator and the photodetector hits, an electrical impulse arises, which is fed to the installation input of trigger 9 and opens the key 5. Thus, the command to measure at the next well point is formed. From key 5, rectangular pulses are sent to RS-flip-flop I) and counter-divider 20. Trigger 10

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is set to one and gives the resolving potential to one of the inputs of the key 13, at the second input of which there is already a resolving potential from the RS flip-flop 11, which is set to one by the pulse "Reset. Therefore, the pulses from the high-frequency generator 22 of the rectangular pulses arrive at the inputs of the keys 14-17. Depending on the initial state of the counting triggers 23 and 24, the outputs of which are connected to the second inputs of the keys 14-16 and 18, the pulses from the high-frequency generator 22 will pass to the summing or subtracting inputs of the reversing counters 26 and 27. Moreover, the initial states of the counting triggers 23 and 24 are selected in such a way that, if high-frequency pulses arrive at the summing input of counter 26, they are fed to counter 27 at the subtractive input. Thus, the absolute temperature code is recorded in one of the counters, and in the other counter it is subtracted from the previous value.

After passing through the divider 20 a certain number of NI pulses (for example: 1000 pulses) coming from the downhole temperature sensor 1, a pulse appears at its output, which flips the RS flip-flop 11 to the zero state. The key 13 is closed and the high-frequency pulses from the generator 22 are not fed to the counters 26 and 27. The number of counted high-frequency pulses that were fed to the summing input of the first reversing counter is proportional to the period of electrical oscillations from the downhole sensor 1, i.e. absolute temperature at a given point of the well. In the second counter, the information on which was fed to the subtracting input, the code is proportional to the temperature difference in two points. Next, the pulses from the divider 20 go to the counter-divider 21, which after counting a certain number of pulses N2 sends a command to the digital-analogue converter 28 Mats from the counter that currently has a temperature difference code. Next, the analog signal is recorded by the recorder 29, for example, a logging logger, AI. At the same time, the pulse of the divider 21 flips the RS flip-flop 12 into one state. It allows me to resolve the P1II potential on the keys 18 and 19. Depending on the state of the counting trigger 25, connected by its input to the RS trigger 10, one of the reversible counters 26 or 27, in which there were information on temperature differences. The second counter stores information about the temperature at a given point in the well. From trigger 12, the “Reset command is sent to reset RS-flip-flops to prepare the device for the next cycle.

After the sensor 1 passes a certain distance from the borehole, determined by the operation of the quantization step formation circuit 8, the operation cycle of the device is repeated.

Thus, it is possible to record the direct gradient of the d-gB well and obtain high sensitivity (on the order of 0.005 ° C), which is largely determined by the magnitude and stability of the frequency of the high-frequency pulse generator. The well testing of the device confirmed its high metrological and operational characteristics.

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Claims (1)

DEVICE FOR MEASURING A TEMPERATURE GRADIENT BY A BOREHOLE, containing a frequency temperature sensor connected by a cable to ground-based equipment, including an amplifier and a rectangular pulse generator, a generator, a counter-divider, a digital-to-analog converter with a recorder, and a measuring roller, characterized in that, for the purpose of to increase the accuracy of measurement, an additional selsyn sensor with a quantization step formation circuit, eight keys, four RS-flip-flops, three countable flip-flops, and a second counter-divider are additionally introduced into it and two reversible counters, the outputs of which are connected to a digital-to-analog converter, and the counting inputs are connected to the outputs of four keys connected by the first inputs to the outputs of two counting triggers, and the second to the output of the key associated with the generator and the outputs of two RS-triggers, and the inputs of the indicated counting flip-flops are connected to the output of the first RS-flip-flop, the input of which is connected to the output of the key controlled by the square-wave pulse generator and the third RS-flip-flop connected to the quantization step generation circuit, and the output of the specified key is connected to the first counter-divider, the output of which is connected to the second RS-trigger and to the input of the second counter-divider, and the output of the latter is connected to the control input of the digital-to-analog converter and the installation input of the fourth RS-trigger, the output of which is connected to the line "Reset" and with the first inputs of two keys, the outputs of which are connected to the installation inputs of the reversible counters, and the other inputs of the keys are connected to the outputs of the third counting trigger, connected by the input to the first RS-trigger. SU,.,. 1255711 I