SU463087A1 - Lateral well logging equipment - Google Patents

Description

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The invention relates to equipment for lateral and electric well logging with element-by-element measurement of the potential of the screen electrode and the current of the central electrode and recording the apparent resistivity (CS) curve on a logarithmic scale.

Known electrical logging equipment with elementwise measurement of potential and current.

The eminencies are also logarithmic, allowing the potential device to stream the potential and current signals, after which the logarithm of the current is subtracted from the logarithm of the voltage and the CS curve is obtained on a logarithmic scale.

In lateral logging equipment, a measuring signal that varies over a wide range is transmitted by two or more telemetric channels of different sensitivity.

The range of variation of the current of the central electrode over the borehole is several thousand amperes, therefore, the transmission of the current signal without distortion is provided by two telemetric channels of different sensitivity. The ratio of the measurement limits of the more sensitive current channel to the measurement limits of the less sensitive gok channel is conveniently chosen to be equal to the base of the logarithm.

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The three telemetric equipment channels, of which one is the telemetric potential channel and two telemetric current channels connected to the inputs of three logarithmic converters, receive the potential signal of the screen electrode (/ e and two current signals

. / o the central electrode, / o and -, where a - is based on the logarithm. From the outputs of logarithmic converters, the signals log Y are removed: ,, log / o and log / n - D, where / is the transfer characteristic of the logarithmic converter.

The log L / g and log / o signals are fed to the input of one of the subtraction circuits, and the signals from the UE and log / o signals are fed to the other, K.

From the output of the first subtraction circuit, the signal is taken and fed to the input of the recorder,

 ,

equal to log, from the output of the second circuit you (1

reading is removed and fed to the register

25 rator signal equal to log

+ K. Both signals are recorded on a logging diagram in the form of two CS curves, shifted one relative to the other by a decade of logarithm30. The known equipment does not ensure the reliability of all points on both QS curves, since the same QS values can be obtained at different values of the thermal and current, including the current and current, which are outside the dynamic range of one or another telemetering device. current channel, where the measurement error exceeds the allowable. In order to isolate unreliable sections of the CS curves: it is necessary to record the control curve of the current of the neutral electrode on a linear scale and, depending on its depth, determine those sections on the curves of the CS where the current flow has gone beyond the dynamic range of a particular TV measuring device current. The purpose of the invention is the creation of equipment, providing it with registration on a single logging chart in one descent of the instrument for the entire range of changes, and their resistance with the required accuracy. This goal is achieved by switching between the logarithmic converters of both current channels and the subtraction circuit of the automatic switch. In order to obtain a logging diagram in the form of one continuous curve, a source of compensating voltage is connected to the input of the automatic switch. As a result, the well logging time is shortened, and the processing and interpretation of the charts are facilitated. The drawing shows a block diagram of the proposed antsarature. The lateral well logging equipment consists of a more sensitive current measurement channel 1, more sensitive current detection channel 2, a potential measurement channel 3, logarithmic converters 4, 5 and 6, an automatic switch 7, a compensating voltage source 8, a subtraction circuit 9, a recorder 10 The outputs of both telemetric current channels 1 and 2 and the telemetric channel of non-potential 3 are connected to the inputs of logarithmic converters 4, 5 and 6, respectively. The outputs of the logarithmic converters 4 and 5 are connected to the input of the automatic switch 7, to which are also connected the outputs of the compensating voltage source 8 and the telemetric current channel 1. The output of the automatic switch 7 is connected to the input of the subtraction circuit 9, to which the output of the logarithmic converter 6 is also connected poteptsiala The output of the subtraction circuit 9 is connected to the registrar 10. The equipment operates as follows. The input of the logarithmic converter 4 receives a current / o signal. At the same time, the input of the logarithmic converter 5 receives a current signal equal to / o / a, where a is the test of the logarithm. From the output of the logarithmic converter 4 is removed and fed to the input of the automatic switch 7 sigpal, equal to log / Q. From the output of the logarithmic converter 5, a signal equal to log / o - K is removed and fed to the other input of the automatic switch. The automatic switch 7 is controlled by the signal of the more sensitive telemetric channel of the current / so that, at the current / o, the upper limit of the measuring range of this channel 1, the automatic switch disconnects from the subtraction circuit 9 the output of the logarithmic converter 4 and connects the output of the logarithmic converter 5 to the less sensitive telemeter meter channel 2. In this case, a signal equal to log / o is sent to the input of the subtraction circuit. At the same time, a compensating signal equal to K is inputted to the subtraction circuit. At a current value of / o corresponding to the lower limit of the range, less than sensitive the current channel, the automatic switch disconnects from the subtraction circuit 9 the output of the logarithmic converter 5 together with the compensating signal meter and connects the output of the logarithmic converter 4. Thus, when switching current channels to the input of the subtraction circuit, the signal equal to log / 0. A signal equal to log U is supplied to the other input of the subtraction circuit. On the f / e input of the recorder, a log - log p signal is sent to the CC. The subject of the invention is the equipment for side logging of wells with a system of element-by-element measurement of the potential of the screen electrode and the current of the central electrode and their subsequent logarithmization, containing one tele measuring channel of the plasma and two tele measuring channels of the current, logarithmic converters connected to the output of each of the telemetric channels and the subtraction potential log and current , characterized in that, in order to ensure the registration of one logging data for one Bora of the whole range of changes in apparent resistances with the required accuracy, an automatic switch is connected between the logarithmic converters of the current channels and the subtraction circuit, which connects the subtraction circuits to the logarif of the measuring device, and the measuring current limit is optimal for this well point.

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