Well diameter and pole plate pressure measuring circuit for micro-resistivity imaging logging

Abstract

The invention discloses a borehole diameter and pole plate pressure measuring circuit for micro-resistivity imaging logging, which is characterized in that constant current is generated by a constant current source module, and the borehole diameter, the pole plate pressure and a resistance signal of a calibration resistor are accurately converted in a voltage form. By means of the current control module and the time-sharing transmission module, transmission of six borehole diameter signals, one polar plate pressure signal and one calibration resistance signal according to the time sequence is achieved. Meanwhile, the calibration resistance signal can be used for calibration, and the influence of the temperature on the measurement result is eliminated. Finally, interference signals are filtered out through a filtering module, and accurate sampling voltage signals are obtained. The device and the method have the advantages of accurately and quickly measuring the borehole diameter and the polar plate pressure signal, and can realize temperature calibration in a high-temperature underground environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial intelligence and relates to a borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging. Background Art

[0002] Micro-resistivity imaging logging adopts the lateral focusing working principle. To reduce the influence of mud shunting in the wellbore, the pad body is closely attached to the well wall by means of a pusher. Alternating current is emitted by the emission electrodes on the pad body and returns to the upper loop electrode of the instrument through the loop formed by the mud in the wellbore and the formation. The pusher, metal connections of the pad body, etc. play a role in potential focusing, enabling the current flowing out of the array electrodes in the middle of the pad to enter the formation perpendicular to the pad surface. Pad pressure is a quantitative characterization parameter of the fit degree between the pad body and the well wall. In engineering applications, it is necessary to determine the appropriate pad pressure through pre-logging design, which should not only ensure that the pad body is closely attached to the well wall to reduce the influence of mud, but also ensure that the friction force between the pad body and the well wall is small enough to reduce the risk of the instrument getting stuck. The borehole diameter curve is an important input curve in the data processing process. The pad images in the instrument (wellbore) coordinate system are serially located in the geodetic coordinate system to accurately obtain geological structure information such as fracture dip and strike. Therefore, micro-resistivity imaging logging needs to measure and record the 6-channel borehole diameter and 1-channel pad pressure signals of its pusher.

[0003] Currently, the measurement of borehole diameter and pad pressure values is mainly obtained by measuring the resistance value of the potentiometer connected to the push arm. During the logging process, due to the sudden change and uncertainty of the wellbore environment, in order to obtain accurate borehole diameter and pad pressure data, the measurement circuit must have the ability of real-time high-precision acquisition. At the same time, the change of downhole temperature will affect the circuit performance, resulting in deviation of the acquisition value, and the signal measurement circuit needs to have a temperature calibration function. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the acquisition accuracy of the measurement circuit in the prior art is low and there is a lack of temperature calibration function, resulting in deviation of the circuit acquisition value, and to provide a borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging includes: a constant current source module, a current control module, a time-division transmission module, and a signal filtering module;

[0007] The constant current source module is connected to the current control module, the current control module is connected to the caliper and plate pressure potentiometers and the calibration resistor; the caliper and plate pressure potentiometers and the calibration resistor are connected to the time-division transmission module; the time-division transmission module is connected to the filtering module; the constant current source module provides a constant current to the current control module; the current control module distributes the current to the potentiometers and calibration resistor of the caliper and plate pressure according to the time sequence to generate corresponding voltage signals; the time-division transmission module transmits the corresponding voltage signals to the signal filtering module according to the time sequence; the filtering module is used to filter out the noise in the voltage signal.

[0008] A further improvement of the present invention lies in:

[0009] Further, the current control module distributes the current to the potentiometers and calibration resistor of the caliper and plate pressure according to the time sequence to generate corresponding voltage signals, and the time-division transmission module transmits the corresponding voltage signals to the signal filtering module according to the time sequence. Specifically, the constant current source module outputs a constant current that flows through the potentiometers of six calipers and one plate pressure and a high-precision standard resistor to generate eight groups of voltage signals. The eight groups of voltage signals are converted into a time-division voltage signal through the time-division transmission module for digital-to-analog conversion and acquisition; the voltage signal generated by the standard resistor is used for calibration of the other seven signals.

[0010] Further, the constant current source module includes: a first reference source U1, a first integrated operational amplifier U2, a first capacitor C1, a first resistor R1, a second resistor R2, and a first transient suppression diode D1; the positive power supply terminal of the first reference source U1 is respectively connected to one end of the first capacitor C1 and the power input port; the other end of the first capacitor C1 is grounded; one end of the second resistor R2 is connected to the output terminal of the first reference source U1, and the other end of the second resistor R2 is respectively connected to the positive input terminal of the first integrated operational amplifier U2 and one end of the first transient suppression diode D1, and the other end of the first transient suppression diode D1 is grounded; one end of the first resistor R1 is respectively connected to the ground terminal of the first reference source U1 and the output terminal of the first integrated operational amplifier U2; the other end of the first resistor R1 is connected to the negative input terminal of the first integrated operational amplifier U2; the positive input terminal of the first integrated operational amplifier U2 is connected to the current control module.

[0011] Further, the current control module includes a third analog switch U3 and a transient suppression diode; the drain terminal DA of the third analog switch U3 is connected to the positive input terminal of the first integrated operational amplifier U2, and the output terminal of the third analog switch U3 is connected to one end of the transient suppression diode; the other end of the transient suppression diode is grounded, the output terminal of the third analog switch U3 is connected to the caliper and plate pressure potentiometers and the standard resistor, and the standard resistor is connected to the time-division transmission module; the first logic input terminal, the second logic input terminal, and the third logic input terminal of the third analog switch U3 are used to receive external timing input signals.

[0012] Further, the output terminals of the third analog switch U3 include a first output terminal, a second output terminal, a third output terminal, a fourth output terminal, a fifth output terminal, a sixth output terminal, a seventh output terminal, and an eighth output terminal; the first output terminal, the second output terminal, the third output terminal, the fourth output terminal, the fifth output terminal, the sixth output terminal, the seventh output terminal, and the eighth output terminal are connected to the borehole diameter and the plate pressure potentiometer as well as the calibration resistor to convert the current signal into a voltage signal.

[0013] Further, the transient suppression diodes include: a second transient suppression diode D2, a third transient suppression diode D3, a fourth transient suppression diode D4, a fifth transient suppression diode D5, a sixth transient suppression diode D6, a seventh transient suppression diode D7, an eighth transient suppression diode D8, and a ninth transient suppression diode D9; one end of the first output terminal of the third analog switch U3 is connected to one end of the second transient suppression diode D2, one end of the second output terminal of the third analog switch U3 is connected to one end of the third transient suppression diode D3, one end of the third output terminal of the third analog switch U3 is connected to one end of the fourth transient suppression diode D4, one end of the fourth output terminal of the third analog switch U3 is connected to one end of the fifth transient suppression diode D5, one end of the fifth output terminal of the third analog switch U3 is connected to one end of the sixth transient suppression diode D6, one end of the sixth output terminal of the third analog switch U3 is connected to one end of the seventh transient suppression diode D7, one end of the seventh output terminal of the third analog switch U3 is connected to one end of the eighth transient suppression diode D8, and one end of the eighth output terminal of the third analog switch U3 is connected to one end of the ninth transient suppression diode D9; the other ends of the second transient suppression diode D2, the third transient suppression diode D3, the fourth transient suppression diode D4, the fifth transient suppression diode D5, the sixth transient suppression diode D6, the seventh transient suppression diode D7, the eighth transient suppression diode D8, and the ninth transient suppression diode D9 are all grounded.

[0014] Further, the time-division transmission module includes a fourth analog switch U4 and a fourth resistor R4. The first input terminal of the fourth analog switch U4 is connected to the first output terminal of the third analog switch U3, the second input terminal of the fourth analog switch U4 is connected to the second output terminal of the third analog switch U3, the third input terminal of the fourth analog switch U4 is connected to the third output terminal of the third analog switch U3, the fourth input terminal of the fourth analog switch U4 is connected to the fourth output terminal of the third analog switch U3, the fifth input terminal of the fourth analog switch U4 is connected to the fifth output terminal of the third analog switch U3, the sixth input terminal of the fourth analog switch U4 is connected to the sixth output terminal of the third analog switch U3, the seventh input terminal of the fourth analog switch U4 is connected to the seventh output terminal of the third analog switch U3, and the eighth input terminal of the fourth analog switch U4 is connected to the eighth output terminal of the third analog switch U3; the eighth input terminal of the fourth analog switch U4 is connected to one end of the fourth resistor R4; the other end of the fourth resistor R4 is grounded. The first logic input terminal, the second logic input terminal, the third logic input terminal, and the enable input terminal of the fourth analog switch U4 are used to receive external timing input signals, and the output terminal of the fourth analog switch U4 is the output terminal of the time-division transmission module.

[0015] Further, the signal filtering module includes a third resistor R3 and a second capacitor C2; one end of the third resistor R3 is connected to the output terminal of the time-division transmission module, the other end of the third resistor R3 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is grounded, and the other end of the third resistor R3 is the output terminal of the signal filtering module.

[0016] Further, the first reference source U1 uses the model LT1021; the first integrated operational amplifier U2 uses the model OPA211; the models of the first transient suppression diode D1, the second transient suppression diode D2, the third transient suppression diode D3, the fourth transient suppression diode D4, the fifth transient suppression diode D5, the sixth transient suppression diode D6, the seventh transient suppression diode D7, the eighth transient suppression diode D8, and the ninth transient suppression diode D9 are all SAC10; the model of the fourth analog switch U4 is ADG1408.

[0017] Further, both the third analog switch U3 and the fourth analog switch U4 are eight-to-one switches.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention precisely converts the signals of well diameter, plate pressure, and calibration resistance value into voltage form by using a constant current generated by a constant current source module. By means of a current control module and a time-division transmission module, the sequential transmission of six well diameter signals, one plate pressure signal, and one calibration resistance signal is achieved. Meanwhile, the calibration resistance signal can be used for calibration to eliminate the influence of temperature on the measurement result. Finally, after filtering out interference signals by a filtering module, an accurate sampled voltage signal is obtained. The present invention has the advantages of accurately and rapidly measuring well diameter and plate pressure signals, and can achieve temperature calibration in a high-temperature downhole environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 Schematic diagram of the well diameter and plate pressure measurement circuit of the present invention;

[0022] Figure 2 Schematic diagram of the constant current source module circuit;

[0023] Figure 3 Schematic diagram of the current control module circuit;

[0024] Figure 4 Schematic diagram of the time-division transmission module circuit;

[0025] Figure 5 Timing diagram of the timing input signal;

[0026] Figure 6 Schematic diagram of the filtering module circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Accordingly, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0029] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0030] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is habitually placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0031] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0032] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] The present invention will be further described in detail below with reference to the accompanying drawings:

[0034] See Figure 1 , the present invention discloses a borehole diameter and pad pressure measurement circuit for microresistivity imaging logging, including: a constant current source module, a current control module, a time-division transmission module, and a signal filtering module;

[0035] The constant current source module is connected to the current control module, the current control module is connected to the caliper and plate pressure potentiometers and the calibration resistor; the caliper and plate pressure potentiometers and the calibration resistor are connected to the time-division transmission module; the time-division transmission module is connected to the filtering module; the constant current source module provides a constant current of a constant magnitude to the current control module; the current control module distributes the current to the potentiometers and calibration resistor of the caliper and plate pressure in sequence to generate corresponding voltage signals; the time-division transmission module transmits the corresponding voltage signals to the signal filtering module in sequence; the filtering module is used to filter out the noise in the voltage signals.

[0036] The constant current source module outputs a constant current that flows through the potentiometers of six calipers and one plate pressure and a high-precision standard resistor to generate eight groups of voltage signals. The eight groups of voltage signals are converted into a single-channel time-division voltage signal through the time-division transmission module for analog-to-digital conversion and acquisition; the voltage signal generated by the standard resistor is used for calibration of the other seven signals.

[0037] The constant current source module includes: a first reference source U1, a first integrated operational amplifier U2, a first capacitor C1, a first resistor R1, a second resistor R2, and a first transient voltage suppression diode D1; the positive power supply terminal of the first reference source U1 is respectively connected to one end of the first capacitor C1 and the power input port; the other end of the first capacitor C1 is grounded; one end of the second resistor R2 is connected to the output terminal of the first reference source U1, and the other end of the second resistor R2 is respectively connected to the positive input terminal of the first integrated operational amplifier U2 and one end of the first transient voltage suppression diode D1, and the other end of the first transient voltage suppression diode D1 is grounded; one end of the first resistor R1 is respectively connected to the ground terminal of the first reference source U1 and the output terminal of the first integrated operational amplifier U2; the other end of the first resistor R1 is connected to the negative input terminal of the first integrated operational amplifier U2; the positive input terminal of the first integrated operational amplifier U2 is connected to the current control module.

[0038] The current control module includes a third analog switch U3 and a transient voltage suppression diode; the drain terminal DA of the third analog switch U3 is connected to the positive input terminal of the first integrated operational amplifier U2, and the output terminal of the third analog switch U3 is connected to one end of the transient voltage suppression diode; the other end of the transient voltage suppression diode is grounded, the output terminal of the third analog switch U3 is connected to the caliper and plate pressure potentiometers and the standard resistor, and the standard resistor is connected to the time-division transmission module; the first logic input terminal, the second logic input terminal, and the third logic input terminal of the third analog switch U3 are used to receive external timing input signals.

[0039] The output terminals of the third analog switch U3 include a first output terminal, a second output terminal, a third output terminal, a fourth output terminal, a fifth output terminal, a sixth output terminal, a seventh output terminal, and an eighth output terminal; the first output terminal, the second output terminal, the third output terminal, the fourth output terminal, the fifth output terminal, the sixth output terminal, the seventh output terminal, and the eighth output terminal are connected to the borehole diameter and the plate pressure potentiometer and the calibration resistor, and convert the current signal into a voltage signal.

[0040] The transient suppression diodes include: a second transient suppression diode D2, a third transient suppression diode D3, a fourth transient suppression diode D4, a fifth transient suppression diode D5, a sixth transient suppression diode D6, a seventh transient suppression diode D7, an eighth transient suppression diode D8, and a ninth transient suppression diode D9; one end of the first output terminal of the third analog switch U3 is connected to one end of the second transient suppression diode D2, one end of the second output terminal of the third analog switch U3 is connected to one end of the third transient suppression diode D3, one end of the third output terminal of the third analog switch U3 is connected to one end of the fourth transient suppression diode D4, one end of the fourth output terminal of the third analog switch U3 is connected to one end of the fifth transient suppression diode D5, one end of the fifth output terminal of the third analog switch U3 is connected to one end of the sixth transient suppression diode D6, one end of the sixth output terminal of the third analog switch U3 is connected to one end of the seventh transient suppression diode D7, one end of the seventh output terminal of the third analog switch U3 is connected to one end of the eighth transient suppression diode D8, and one end of the eighth output terminal of the third analog switch U3 is connected to one end of the ninth transient suppression diode D9; the other ends of the second transient suppression diode D2, the third transient suppression diode D3, the fourth transient suppression diode D4, the fifth transient suppression diode D5, the sixth transient suppression diode D6, the seventh transient suppression diode D7, the eighth transient suppression diode D8, and the ninth transient suppression diode D9 are all grounded.

[0041] The time-sharing transmission module includes a fourth analog switch U4 and a fourth resistor R4. The first input terminal of the fourth analog switch U4 is connected to the first output terminal of the third analog switch U3, the second input terminal of the fourth analog switch U4 is connected to the second output terminal of the third analog switch U3, the third input terminal of the fourth analog switch U4 is connected to the third output terminal of the third analog switch U3, the fourth input terminal of the fourth analog switch U4 is connected to the fourth output terminal of the third analog switch U3, the fifth input terminal of the fourth analog switch U4 is connected to the fifth output terminal of the third analog switch U3, the sixth input terminal of the fourth analog switch U4 is connected to the sixth output terminal of the third analog switch U3, the seventh input terminal of the fourth analog switch U4 is connected to the seventh output terminal of the third analog switch U3, and the eighth input terminal of the fourth analog switch U4 is connected to the eighth output terminal of the third analog switch U3; the eighth input terminal of the fourth analog switch U4 is connected to one end of the fourth resistor R4; the other end of the fourth resistor R4 is grounded. The first logic input terminal, the second logic input terminal, the third logic input terminal, and the enable input terminal of the fourth analog switch U4 are used to receive external timing input signals, and the output terminal of the fourth analog switch U4 is the output terminal of the time-sharing transmission module.

[0042] The signal filtering module includes a third resistor R3 and a second capacitor C2; one end of the third resistor R3 is connected to the output terminal of the time-sharing transmission module, the other end of the third resistor R3 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is grounded. The other end of the third resistor R3 is the output terminal of the signal filtering module.

[0043] The first reference source U1 uses the model LT1021; the first integrated operational amplifier U2 uses the model OPA211; the models of the first transient suppression diode D1, the second transient suppression diode D2, the third transient suppression diode D3, the fourth transient suppression diode D4, the fifth transient suppression diode D5, the sixth transient suppression diode D6, the seventh transient suppression diode D7, the eighth transient suppression diode D8, and the ninth transient suppression diode D9 are all SAC10; the model of the fourth analog switch U4 is ADG1408. The third analog switch U3 and the fourth analog switch U4 are both eight-to-one switches.

[0044] Embodiment:

[0045] Refer to Figure 1, an embodiment of the present invention relates to a measurement circuit for well diameter signals and pad pressure signals in micro-resistivity imaging logging, which includes a constant current source module, a current control module, a time-division transmission module, and a signal filtering module. In this embodiment, the constant current source module generates a direct current with a constant magnitude, and this current is input into the well diameter and pad pressure potentiometers and calibration resistors through the current control module to be converted into voltage signals. The 8-channel voltage signals are changed into 1-channel time-division voltage signals through the time-division transmission module. Finally, these time-division voltage signals are filtered through the signal filtering module to obtain accurate voltage signals, realizing the accurate measurement of the well diameter and pad pressure.

[0046] Refer to Figure 2 , the constant current source circuit includes a first reference source U1, a first integrated operational amplifier U2, a first capacitor C1, a first resistor R1, a second resistor R2, and a first transient suppression diode D1. In this embodiment, in order to meet the requirement of accurately outputting a constant current in the downhole high-temperature environment, component models with excellent characteristics are carefully selected. The first reference source U1 uses the model LT1021, the first integrated operational amplifier U2 uses the model OPA211, and the first transient suppression diode D1 uses the model SAC10. These components have key characteristics such as small temperature drift and low noise. Specifically for the circuit connection in Embodiment 2, the positive power supply terminal of the first reference source U1 is grounded with the first capacitor C1. One end of the second resistor R2 is connected to the output terminal of the first reference source, and the other end is connected to the positive input terminal of the first integrated operational amplifier U2 and grounded through the first transient suppression diode D1. One end of the first resistor R1 is connected to the ground terminal of the first reference source U1, and at the same time, this end is also connected to the output terminal of the first integrated operational amplifier U2. The other end of the first resistor R1 is connected to the negative input terminal of the first integrated operational amplifier U2. The current output terminal of the constant current source module is the positive terminal of the first integrated operational amplifier U2, which is used to provide an accurate constant current for the well diameter signal and the pad pressure signal.

[0047] Refer to Figure 3, the current control module includes a third analog switch U3, a second transient voltage suppressor diode D2, a third transient voltage suppressor diode D3, a fourth transient voltage suppressor diode D4, a fifth transient voltage suppressor diode D5, a sixth transient voltage suppressor diode D6, a seventh transient voltage suppressor diode D7, an eighth transient voltage suppressor diode D8, and a ninth transient voltage suppressor diode D9. Among them, the model of the third analog switch U3 is preferably ADG1408, and the model of the transient voltage suppressor diode is preferably SAC10. The drain terminal I1 of the third analog switch is connected to the output terminal I1 of the above constant current source module. The eight source terminals of the third analog switch U3 are respectively connected to the ground through the transient voltage suppressor diodes D2 to D9 to prevent instantaneous overshoot. The current control module includes the first logic input terminal, the second logic input terminal, and the third logic input terminal of the third analog switch, that is, A0, A1, and A2 are connected to the external timing input signal. The current output terminals of the current control module are the first to eighth source terminals of the third analog switch U3, that is, I2 - I9. The current output of the source terminal acts on the caliper and the plate pressure potentiometer and the standard resistor, converting 8 groups of current signals into voltage signals, and the voltage signals are output to the time-division transmission module.

[0048] Refer to Figure 4 The time-division transmission module includes a fourth analog switch U4 and a fourth resistor R4. The model of the fourth analog switch U4 is preferably ADG1408. The eight source terminals of the fourth analog switch U4 are connected to the eight source terminals of the third analog switch U3 in the current control module, that is, I2 - I9. The eighth source terminal is connected to the ground through the fourth resistor R4. The first logic input terminal, the second logic input terminal, and the third logic input terminal of the fourth analog switch U4 are respectively connected to the external control signal, that is, A0, A1, and A2. It should be noted here that the fourth resistor R4 is used for temperature calibration, that is, the above standard resistor.

[0049] Refer to Figure 5 The shown A0, A1, and A2 are a specific form of the external input timing signal. The external input logic signal is used for the A0, A1, and A2 ports of the third analog switch U3 and the fourth analog switch U4, and its logical combination realizes the switching operation of the analog switch.

[0050] Refer to Figure 4 , a filter module body circuit structure form is provided. The shown module is composed of a third resistor R3 and a second capacitor C2. One end of the third resistor R3 is connected to the output terminal of the time-division transmission module, that is, u1. The other end of the third resistor R3 is connected to the ground through the second capacitor C2, and this end is also the output terminal of the signal filtering module. The output voltage value is a clean voltage value after removing noise and is available for analog-to-digital conversion acquisition.

[0051] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging, characterized in that, it includes: a constant current source module, a current control module, a time-division transmission module, and a signal filtering module; the constant current source module is connected to the current control module, the current control module is connected to the borehole diameter and pad pressure potentiometers and a calibration resistor; the borehole diameter and pad pressure potentiometers and the calibration resistor are connected to the time-division transmission module; the time-division transmission module is connected to the filtering module; the constant current source module provides a constant current to the current control module; the current control module distributes the current to the potentiometers and calibration resistor of the borehole diameter and pad pressure according to a time sequence to generate corresponding voltage signals; the time-division transmission module transmits the corresponding voltage signals to the signal filtering module according to a time sequence; the filtering module is used to filter out the noise in the voltage signal.

2. The borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 1, characterized in that, the current control module distributes the current to the potentiometers and calibration resistor of the borehole diameter and pad pressure according to a time sequence to generate corresponding voltage signals, and the time-division transmission module transmits the corresponding voltage signals to the signal filtering module according to a time sequence, specifically: the constant current source module outputs a constant current that flows through the potentiometers of six borehole diameters and one pad pressure and a high-precision standard resistor to generate eight groups of voltage signals, and the eight groups of voltage signals are converted into a time-division voltage signal through the time-division transmission module for analog-to-digital conversion and acquisition; the voltage signal generated by the standard resistor is used for calibration of the other seven signals.

3. The borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 1, characterized in that, the constant current source module includes: a first reference source U1, a first integrated operational amplifier U2, a first capacitor C1, a first resistor R1, a second resistor R2, and a first transient voltage suppressor diode D1; the positive power supply terminal of the first reference source U1 is respectively connected to one end of the first capacitor C1 and the power input port; the other end of the first capacitor C1 is grounded; one end of the second resistor R2 is connected to the output terminal of the first reference source U1, and the other end of the second resistor R2 is respectively connected to the positive input terminal of the first integrated operational amplifier U2 and one end of the first transient voltage suppressor diode D1, and the other end of the first transient voltage suppressor diode D1 is grounded; one end of the first resistor R1 is respectively connected to the ground terminal of the first reference source U1 and the output terminal of the first integrated operational amplifier U2; the other end of the first resistor R1 is connected to the negative input terminal of the first integrated operational amplifier U2; the positive input terminal of the first integrated operational amplifier U2 is connected to the current control module.

4. The borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 3, characterized in that, The current control module includes a third analog switch U3 and a transient suppression diode; the drain terminal DA of the third analog switch U3 is connected to the positive input terminal of the first integrated operational amplifier U2, and the output terminal of the third analog switch U3 is connected to one end of the transient suppression diode; the other end of the transient suppression diode is grounded, the output terminal of the third analog switch U3 is connected to the caliper and pad pressure potentiometer and a standard resistor, and the standard resistor is connected to the time-division transmission module; the first logic input terminal, the second logic input terminal, and the third logic input terminal of the third analog switch U3 are used to receive external timing input signals.

5. The caliper and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 4, characterized in that the output terminal of the third analog switch U3 includes a first output terminal, a second output terminal, a third output terminal, a fourth output terminal, a fifth output terminal, a sixth output terminal, a seventh output terminal, and an eighth output terminal; the first output terminal, the second output terminal, the third output terminal, the fourth output terminal, the fifth output terminal, the sixth output terminal, the seventh output terminal, and the eighth output terminal are connected to the caliper and pad pressure potentiometer and a calibration resistor to convert the current signal into a voltage signal.

6. The caliper and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 5, characterized in that the transient suppression diode includes: a second transient suppression diode D2, a third transient suppression diode D3, a fourth transient suppression diode D4, a fifth transient suppression diode D5, a sixth transient suppression diode D6, a seventh transient suppression diode D7, an eighth transient suppression diode D8, and a ninth transient suppression diode D9; the first output terminal of the third analog switch U3 is connected to one end of the second transient suppression diode D2, the second output terminal of the third analog switch U3 is connected to one end of the third transient suppression diode D3, the third output terminal of the third analog switch U3 is connected to one end of the fourth transient suppression diode D4, the fourth output terminal of the third analog switch U3 is connected to one end of the fifth transient suppression diode D5, the fifth output terminal of the third analog switch U3 is connected to one end of the sixth transient suppression diode D6, the sixth output terminal of the third analog switch U3 is connected to one end of the seventh transient suppression diode D7, the seventh output terminal of the third analog switch U3 is connected to one end of the eighth transient suppression diode D8, and the eighth output terminal of the third analog switch U3 is connected to one end of the ninth transient suppression diode D9; the other ends of the second transient suppression diode D2, the third transient suppression diode D3, the fourth transient suppression diode D4, the fifth transient suppression diode D5, the sixth transient suppression diode D6, the seventh transient suppression diode D7, the eighth transient suppression diode D8, and the ninth transient suppression diode D9 are all grounded.

7. The caliper and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 6, characterized in that The time-division transmission module includes a fourth analog switch U4 and a fourth resistor R4; a first input terminal of the fourth analog switch U4 is connected to a first output terminal of a third analog switch U3, a second input terminal of the fourth analog switch U4 is connected to a second output terminal of the third analog switch U3, a third input terminal of the fourth analog switch U4 is connected to a third output terminal of the third analog switch U3, a fourth input terminal of the fourth analog switch U4 is connected to a fourth output terminal of the third analog switch U3, a fifth input terminal of the fourth analog switch U4 is connected to a fifth output terminal of the third analog switch U3, a sixth input terminal of the fourth analog switch U4 is connected to a sixth output terminal of the third analog switch U3, a seventh input terminal of the fourth analog switch U4 is connected to a seventh output terminal of the third analog switch U3, and an eighth input terminal of the fourth analog switch U4 is connected to an eighth output terminal of the third analog switch U3; the eighth input terminal of the fourth analog switch U4 is connected to one end of the fourth resistor R4; the other end of the fourth resistor R4 is grounded, and a first logic input terminal, a second logic input terminal, a third logic input terminal, and an enable input terminal of the fourth analog switch U4 are used to receive an external timing input signal, and an output terminal of the fourth analog switch U4 is an output terminal of the time-division transmission module.

8. The borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 7, wherein, the signal filtering module includes a third resistor R3 and a second capacitor C2; one end of the third resistor R3 is connected to the output terminal of the time-division transmission module, the other end of the third resistor R3 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is grounded, and the other end of the third resistor R3 is the output terminal of the signal filtering module.

9. The borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 8, wherein, the first reference source U1 uses the model LT1021; the first integrated operational amplifier U2 uses the model OPA211; the models of the first transient suppression diode D1, the second transient suppression diode D2, the third transient suppression diode D3, the fourth transient suppression diode D4, the fifth transient suppression diode D5, the sixth transient suppression diode D6, the seventh transient suppression diode D7, the eighth transient suppression diode D8, and the ninth transient suppression diode D9 are all SAC10; the model of the fourth analog switch U4 is ADG1408.

10. The borehole diameter and pad pressure measurement circuit for micro-resistivity imaging logging according to claim 9, wherein, both the third analog switch U3 and the fourth analog switch U4 are eight-to-one switches.

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