Phase difference measuring device for resistivity measurement while drilling

Abstract

The application discloses a phase difference measuring device for resistivity measurement while drilling, which comprises a first automatic gain adjusting circuit, a second automatic gain adjusting circuit, a waveform converting circuit, a duty cycle calculating circuit and a direct current converting circuit. The first automatic gain adjusting circuit is used for automatically gain adjusting a first electromagnetic wave signal to obtain a first adjusted signal, and the second automatic gain adjusting circuit is used for automatically gain adjusting a second electromagnetic wave signal to obtain a second adjusted signal. The waveform converting circuit is used for respectively converting the waveforms of the first adjusted signal and the second adjusted signal to obtain a first square wave signal and a second square wave signal. The duty cycle calculating circuit is used for obtaining a third square wave signal according to the first square wave signal and the second square wave signal. The direct current converting circuit is used for obtaining a direct current voltage according to the third square wave signal, and the direct current voltage is used for obtaining the resistivity while drilling. The device has a wider adjusting range, excellent anti-interference ability and higher stability.

Description

Technical Field

[0001] This invention relates to the field of logging while drilling technology, and in particular to a phase difference measuring device for measuring resistivity while drilling. Background Technology

[0002] Logging while drilling (LOW) is a key technology in drilling engineering, and various LOW methods and instruments are widely used in oil exploration and production. By measuring, processing, transmitting, and interpreting various physical information about the formation, such as electrical, acoustic, nuclear, and magnetic data, engineers can determine whether the drilling conditions are safe and whether the underground oil and gas reserves are abundant. Measuring the resistivity parameters of the drilled formation not only provides useful guidance information for the drilling system but also provides indispensable geological parameters for real-time comprehensive formation evaluation. However, in LOW resistivity logging technologies, the complex downhole environment, including temperature, humidity, and vibration, leads to problems such as large signal amplitude variations and low accuracy in phase difference calculations. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the object of this invention is to provide a phase difference measuring device for measuring resistivity while drilling, which has a wide adjustment range, excellent anti-interference ability, and higher stability.

[0004] To achieve the above objectives, a first aspect of the present invention provides a phase difference measuring device for measuring resistivity while drilling, the device comprising: a first automatic gain control circuit, a second automatic gain control circuit, a waveform conversion circuit, a duty cycle calculation circuit, and a DC conversion circuit;

[0005] The first automatic gain control circuit is used to automatically adjust the gain of the first electromagnetic wave signal to obtain a first adjustment signal, and the second automatic gain control circuit is used to automatically adjust the gain of the second electromagnetic wave signal to obtain a second adjustment signal. The first electromagnetic wave signal and the second electromagnetic wave signal both contain the measured stratum information, and the difference between the amplitude of the first adjustment signal and the amplitude of the second adjustment signal is less than a preset difference.

[0006] The waveform conversion circuit is used to convert the first adjustment signal and the second adjustment signal into waveforms respectively, so as to obtain a first square wave signal and a second square wave signal with the same duty cycle and frequency.

[0007] The duty cycle calculation circuit is used to obtain a third square wave signal based on the first square wave signal and the second square wave signal, wherein the duty cycle of the third square wave signal is the phase difference between the first square wave signal and the second square wave signal;

[0008] The DC-DC conversion circuit is used to obtain a DC voltage based on the third wave signal, wherein the DC voltage is used to obtain the drilling resistivity.

[0009] In addition, the phase difference measuring device for measuring resistivity while drilling according to the above embodiments of the present invention may also have the following additional technical features:

[0010] According to an embodiment of the present invention, both the first electromagnetic wave signal and the second electromagnetic wave signal are sinusoidal signals. The first automatic gain control circuit and the second automatic gain control circuit have the same structure. The first automatic gain control circuit includes a transconductance amplifier circuit, a signal conditioning circuit, and an integrator circuit. The input terminal of the transconductance amplifier circuit is used to input the first electromagnetic wave signal. The output terminal of the transconductance amplifier circuit is connected to the input terminal of the signal conditioning circuit. The control terminal of the transconductance amplifier circuit is connected to the output terminal of the integrator circuit. The first output terminal of the signal conditioning circuit is connected to the waveform conversion circuit. The second output terminal of the signal conditioning circuit is connected to the input terminal of the integrator circuit.

[0011] The transconductance amplifier circuit is used to adjust its own amplification factor according to the control signal output by the integrator circuit, and amplify the first electromagnetic wave signal based on the amplification factor. The signal conditioning circuit is used to rectify the amplified first electromagnetic wave signal, and the integrator circuit is used to integrate the rectified first electromagnetic wave signal to obtain the control signal.

[0012] According to an embodiment of the present invention, the transconductance amplifier circuit includes: a transconductance amplifier, a first resistor, a second resistor, and a third resistor. The first terminal of the first resistor is connected to the non-inverting input of the transconductance amplifier and is used to input the first electromagnetic wave signal. The second terminal of the first resistor is grounded. The first terminal of the second resistor is connected to the inverting input of the transconductance amplifier and the first terminal of the third resistor, respectively. The second terminal of the second resistor is grounded. The second terminal of the third resistor is connected to the output terminal of the transconductance amplifier. The output terminal of the transconductance amplifier is connected to the input terminal of the signal conditioning circuit. The control terminal of the transconductance amplifier is connected to the output terminal of the integrator circuit.

[0013] According to one embodiment of the present invention, the signal conditioning circuit includes: a first operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first diode, and a second diode. The first terminal of the fourth resistor is connected to the non-inverting input of the first operational amplifier, and the second terminal of the fourth resistor is grounded. The first terminal of the fifth resistor is connected to the output terminal of the transconductance amplifier circuit and the first terminal of the eighth resistor, respectively. The second terminal of the fifth resistor is connected to the inverting input of the first operational amplifier and the first terminal of the sixth resistor, respectively. The second terminal of the sixth resistor is connected to the output terminal of the first operational amplifier and the first terminal of the seventh resistor, respectively. The second terminal of the seventh resistor is connected to the anode of the first diode, and the second terminal of the eighth resistor is connected to the anode of the second diode. The output terminal of the first operational amplifier serves as the first output terminal of the signal conditioning circuit, and the cathode of the first diode is connected to the cathode of the second diode and serves as the second output terminal of the signal conditioning circuit.

[0014] According to one embodiment of the present invention, the integrating circuit includes: a second operational amplifier, a ninth resistor, a tenth resistor, a first capacitor, and a second capacitor. The first terminal of the ninth resistor is connected to the second output terminal of the signal conditioning circuit and the inverting input of the second operational amplifier, respectively. The second terminal of the ninth resistor is connected to the first terminal of the tenth resistor. The second terminal of the tenth resistor is connected to the output terminal of the second operational amplifier. The non-inverting input of the second operational amplifier is grounded. The first capacitor is connected in parallel with the ninth resistor, and the second capacitor is connected in parallel with the tenth resistor. The output terminal of the second operational amplifier serves as the output terminal of the integrating circuit.

[0015] According to an embodiment of the present invention, the waveform conversion circuit includes: a first comparator and a second comparator, wherein the non-inverting input of the first comparator is connected to the output of the first automatic gain adjustment circuit, the inverting input of the first comparator is grounded, and the output of the first comparator outputs the first square wave signal; the non-inverting input of the second comparator is connected to the output of the second automatic gain adjustment circuit, the inverting input of the second comparator is grounded, and the output of the second comparator outputs the second square wave signal.

[0016] According to one embodiment of the present invention, the duty cycle calculation circuit includes: a first D flip-flop, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, and a sixteenth resistor. The first end of the eleventh resistor is connected to a first preset power supply, and the second end of the eleventh resistor is connected to the first set pin of the D flip-flop. The first end of the twelfth resistor is connected to a second preset power supply, and the second end of the twelfth resistor is connected to the first data input pin of the D flip-flop. The first end of the thirteenth resistor R13 is used to input the first square wave signal, and the second end of the thirteenth resistor is connected to the first clock pin of the D flip-flop. The first end of the fourteenth resistor is connected to a third preset power supply, and the second end of the fourteenth resistor is connected to the second set pin of the D flip-flop. The first end of the fifteenth resistor is connected to a fourth preset power supply, and the second end of the fifteenth resistor is connected to the second data input pin of the D flip-flop. The first end of the sixteenth resistor is used to input the second square wave signal, and the second end of the sixteenth resistor is connected to the second clock pin of the D flip-flop. The first reset pin of the D flip-flop is connected to the second output pin, and the first output pin of the D flip-flop is connected to the second reset pin and used to output the third square wave signal.

[0017] According to an embodiment of the present invention, the phase difference measuring device for measuring resistivity while drilling, the DC-DC conversion circuit includes: a third operational amplifier, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a third capacitor, a fourth capacitor, and a fifth capacitor. The first terminal of the seventeenth resistor is used to input the third wave signal. The second terminal of the seventeenth resistor is connected to the first terminal of the third capacitor and the first terminal of the eighteenth resistor. The second terminal of the eighteenth resistor is connected to the first terminal of the nineteenth resistor and the first terminal of the fifth capacitor. The second terminal of the nineteenth resistor is connected to the non-inverting input of the third operational amplifier and the first terminal of the fourth capacitor. The second terminal of the fourth capacitor is grounded. The second terminal of the fifth capacitor is connected to the output terminal of the third operational amplifier. The inverting input of the third operational amplifier is connected to the output terminal of the third operational amplifier. The output terminal of the third operational amplifier is used to output the DC voltage.

[0018] According to one embodiment of the present invention, the resistance value of the first resistor is in the range of 20kΩ-47kΩ.

[0019] According to one embodiment of the present invention, the capacitance values ​​of the first capacitor and the second capacitor are in the range of 47nF-100nF.

[0020] The phase difference measuring device for drilling resistivity measurement in this embodiment of the invention has a wide adjustment range, excellent anti-interference ability and higher stability. Attached Figure Description

[0021] Figure 1 This is a structural block diagram of a phase difference measuring device for measuring resistivity while drilling, according to an embodiment of the present invention.

[0022] Figure 2 This is a structural block diagram of a first automatic gain control circuit according to an embodiment of the present invention;

[0023] Figure 3 This is a circuit diagram of a transconductance amplifier circuit according to an embodiment of the present invention;

[0024] Figure 4 This is a circuit diagram of a signal conditioning circuit according to an embodiment of the present invention;

[0025] Figure 5 This is a circuit diagram of an integrating circuit according to an embodiment of the present invention;

[0026] Figure 6 This is a circuit diagram of a waveform conversion circuit according to an embodiment of the present invention;

[0027] Figure 7 This is a circuit diagram of a duty cycle calculation circuit according to an embodiment of the present invention;

[0028] Figure 8 This is a circuit diagram of a DC-DC converter circuit according to an embodiment of the present invention. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] The phase difference measuring device for measuring resistivity while drilling according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0031] Figure 1 This is a structural block diagram of a phase difference measuring device for measuring resistivity while drilling, according to an embodiment of the present invention.

[0032] like Figure 1 As shown, the phase difference measuring device 10 for measuring resistivity while drilling includes: a first automatic gain adjustment circuit 100, a second automatic gain adjustment circuit 100', a waveform conversion circuit 104, a duty cycle calculation circuit 105, and a DC conversion circuit 106.

[0033] The first automatic gain control circuit 100 is used to automatically adjust the gain of the first electromagnetic wave signal to obtain a first adjustment signal, and the second automatic gain control circuit 100' is used to automatically adjust the gain of the second electromagnetic wave signal to obtain a second adjustment signal. The first electromagnetic wave signal and the second electromagnetic wave signal both contain the measured stratum information, and the difference between the amplitude of the first adjustment signal and the amplitude of the second adjustment signal is less than a preset difference.

[0034] The waveform conversion circuit 104 is used to convert the first adjustment signal and the second adjustment signal into waveforms respectively, so as to obtain a first square wave signal SQR_R1 and a second square wave signal SQR_R2 with the same duty cycle and frequency.

[0035] The duty cycle calculation circuit 105 is used to obtain a third square wave signal SQR_R3 based on the first square wave signal SQR_R1 and the second square wave signal SQR_R2, wherein the duty cycle of the third square wave signal SQR_R3 is the phase difference between the first square wave signal SQR_R1 and the second square wave signal SQR_R2.

[0036] The DC-DC converter circuit 106 is used to obtain the DC voltage based on the third wave signal SQR_R3, wherein the DC voltage is used to obtain the drilling resistivity.

[0037] The first electromagnetic wave signal and the second electromagnetic wave signal can be sinusoidal signals. In actual operation, the amplitudes of the first electromagnetic wave signal and the second electromagnetic wave signal are different, which will cause a small error in the phase difference calculation, thus affecting the measurement accuracy. Based on this, the present invention obtains a first adjustment signal and a second adjustment signal with similar amplitudes through the first automatic gain adjustment circuit 100 and the second automatic gain adjustment circuit 100' to ensure measurement accuracy.

[0038] The phase difference measuring device for drilling resistivity measurement in this embodiment of the invention has a wide adjustment range, excellent anti-interference ability and higher stability.

[0039] In some embodiments, both the first electromagnetic wave signal and the second electromagnetic wave signal are sinusoidal signals, and the first automatic gain control circuit 100 and the second automatic gain control circuit 100' have the same structure, such as... Figure 2 As shown, the first automatic gain control circuit 100 includes a transconductance amplifier circuit 101, a signal conditioning circuit 102, and an integrator circuit 103. The input terminal of the transconductance amplifier circuit 101 is used to input a first electromagnetic wave signal. The output terminal of the transconductance amplifier circuit 101 is connected to the input terminal of the signal conditioning circuit 102. The control terminal of the transconductance amplifier circuit 101 is connected to the output terminal of the integrator circuit 103. The first output terminal of the signal conditioning circuit 102 is connected to the waveform conversion circuit 104, and the second output terminal of the signal conditioning circuit 102 is connected to the input terminal of the integrator circuit 103.

[0040] The transconductance amplifier circuit 101 is used to adjust its own amplification factor according to the control signal output by the integrator circuit 103, and amplify the first electromagnetic wave signal based on the amplification factor. The signal conditioning circuit 102 is used to rectify the amplified first electromagnetic wave signal, and the integrator circuit 103 is used to integrate the rectified first electromagnetic wave signal to obtain the control signal.

[0041] Specifically, the transconductance amplifier circuit 101 is used to design the basic amplification factor and adjust the amplification factor by controlling the current flowing into the control terminal CON. The signal conditioning circuit 102 is used to rectify the AC signal output from the transconductance amplifier circuit 101. The integrator circuit 103 is used to convert the rectified voltage value output from the signal conditioning circuit 102 into a DC voltage value, which is then input to the control terminal CON of the transconductance amplifier circuit 101.

[0042] In some embodiments, such as Figure 3 As shown, the transconductance amplifier circuit 101 includes: a transconductance amplifier U1, a first resistor R1, a second resistor R2, and a third resistor R3. The first terminal of the first resistor R1 is connected to the non-inverting input of the transconductance amplifier U1 and is used to input a first electromagnetic wave signal. The second terminal of the first resistor is grounded. The first terminal of the second resistor R2 is connected to both the inverting input of the transconductance amplifier U1 and the first terminal of the third resistor R3. The second terminal of the second resistor R2 is grounded. The second terminal of the third resistor R3 is connected to the output terminal of the transconductance amplifier U1. The output terminal of the transconductance amplifier U1 is connected to the input terminal of the signal conditioning circuit. The control terminal of the transconductance amplifier U1 is connected to the output terminal of the integrator circuit 103.

[0043] The resistance value of the first resistor R1 can range from 20kΩ to 47kΩ.

[0044] Specifically, the transconductance amplifier circuit 101 sets the maximum gain value by setting the resistance values ​​of resistors R1 and R2, and reduces the gain value by controlling the current flowing into the control terminal CON.

[0045] In some embodiments, such as Figure 4As shown, the signal conditioning circuit 102 includes: a first operational amplifier U2, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first diode D1, and a second diode D2. The first terminal of the fourth resistor R4 is connected to the non-inverting input of the first operational amplifier U2, and the second terminal of the fourth resistor R4 is grounded. The first terminal of the fifth resistor R5 is connected to the output terminal of the transconductance amplifier circuit 101 and the first terminal of the eighth resistor R8. The second terminal of the fifth resistor R5 is connected to the inverting input of the first operational amplifier U2 and the first terminal of the sixth resistor R6. The second terminal of the sixth resistor R6 is connected to the output terminal of the first operational amplifier U2 and the first terminal of the seventh resistor R7. The second terminal of the seventh resistor R7 is connected to the anode of the first diode D1. The second terminal of the eighth resistor R8 is connected to the anode of the second diode D2.

[0046] In this circuit, the output terminal of the first operational amplifier U2 serves as the first output terminal of the signal conditioning circuit 102, and the cathode of the first diode D1 is connected to the cathode of the second diode D2, serving as the second output terminal of the signal conditioning circuit 102.

[0047] Specifically, the signal conditioning circuit 102 inverts the output V2 of the transconductance amplifier circuit 101 through the first operational amplifier U2, and simultaneously takes V2. The two signals, V2 and its inverted signal, are then rectified by full-wave through D1 and D2 and output as signal V3 to the integrator circuit 103.

[0048] In some embodiments, such as Figure 5 As shown, the integrating circuit 103 includes: a second operational amplifier U3, a ninth resistor R9, a tenth resistor R10, a first capacitor C1, and a second capacitor C2. The first terminal of the ninth resistor R9 is connected to the second output terminal of the signal conditioning circuit 102 and the inverting terminal of the second operational amplifier U3. The second terminal of the ninth resistor R9 is connected to the first terminal of the tenth resistor R10. The second terminal of the tenth resistor R10 is connected to the output terminal of the second operational amplifier U3. The non-inverting terminal of the second operational amplifier U3 is grounded. The first capacitor C1 is connected in parallel with the ninth resistor R9, and the second capacitor C2 is connected in parallel with the tenth resistor R10. The output terminal of the second operational amplifier U3 serves as the output terminal of the integrating circuit 103.

[0049] The capacitance values ​​of the first capacitor C1 and the second capacitor C2 can range from 47nF to 100nF.

[0050] Specifically, the integrating circuit 103 integrates the signal V3 through the second operational amplifier U3 to obtain a DC voltage. The magnitude of the DC voltage can be set by adjusting the values ​​of capacitors C1 and C2. The current at the control terminal CON of the input transconductance amplifier circuit 101 can be adjusted by setting the value of resistor R11.

[0051] The first automatic gain control circuit 100 in this embodiment of the invention adopts the basic principle of negative feedback. When the first electromagnetic wave signal increases, the output V2 of the transconductance amplifier circuit 101 also increases, the output V3 of the signal conditioning circuit 102 also increases, and the output V_CON of the integrator circuit 103 also increases. At this time, the current flowing into the control terminal CON of the transconductance amplifier circuit 101 decreases, causing the output V2 of the transconductance amplifier circuit 101 to decrease as well. This forms negative feedback, which allows a larger amplification factor to be obtained when a small signal is input, and a smaller amplification factor to be obtained when a large signal is input.

[0052] In some embodiments, such as Figure 6 As shown, the waveform conversion circuit 104 includes: a first comparator U4A and a second comparator U4B. The non-inverting input of the first comparator U4A is connected to the output of the first automatic gain control circuit 100, and the inverting input of the first comparator U4A is grounded. The output of the first comparator outputs a first square wave signal SQR_R1. The non-inverting input of the second comparator U4B is connected to the output of the second automatic gain control circuit 100', and the inverting input of the second comparator U4B is grounded. The output of the second comparator U4B outputs a second square wave signal SQR_R2.

[0053] Specifically, the first adjustment signal is SIN_R1, and the second adjustment signal is SIN_R2. When the input signal SIN_R1 is greater than 0, the first comparator U4A outputs a high level; when the input signal SIN_R1 is less than 0, the first comparator U4A outputs a 0 level. When the input signal SIN_R2 is greater than 0, the second comparator U4B outputs a high level; when the input signal SIN_R1 is less than 0, the second comparator U4B outputs a 0 level. In this way, the AC sine wave signal is converted into square wave signals SQR_R1 and SQR_R2.

[0054] In some embodiments, such as Figure 7As shown, the duty cycle calculation circuit 105 includes: a first D flip-flop U5, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, and a sixteenth resistor R16. The first end of the eleventh resistor R11 is connected to a first preset power supply, and the second end of the eleventh resistor R11 is connected to the first set pin 1PR of the first D flip-flop U5. The first end of the twelfth resistor R12 is connected to a second preset power supply, and the second end of the twelfth resistor R12 is connected to the first data input pin 1D of the first D flip-flop U5. The first end of the thirteenth resistor R13 is used to input a first square wave signal SQR_R1, and the second end of the thirteenth resistor R13 is connected to the first clock pin 1CLK of the first D flip-flop U5. The first end of the fourteenth resistor R14 is connected to the third preset power supply. The second end of the fourteenth resistor R14 is connected to the second set pin 2PR of the first D flip-flop U5. The first end of the fifteenth resistor R15 is connected to the fourth preset power supply. The second end of the fifteenth resistor R15 is connected to the second data input pin 2D of the first D flip-flop U5. The first end of the sixteenth resistor R16 is used to input the second square wave signal SQR_R2. The second end of the sixteenth resistor R16 is connected to the second clock pin 2CLK of the first D flip-flop U5. The first reset pin 1CLR of the D flip-flop U5 is connected to the second output pin ~2Q. The first output pin 1Q of the first D flip-flop U5 is connected to the second reset pin 2CLR and is used to output the third square wave signal SQR_R3.

[0055] Specifically, when the input signal SQR_R1 has a rising edge, the output signal SQR_R3 outputs a high level and maintains that level. When the input signal SQR_R2 has a rising edge, the output signal SQR_R3 outputs a low level and maintains that level. Thus, a third wave signal SQR_R3 is obtained, corresponding one-to-one with the difference between the rising edges of SQR_R1 and SQR_R2. The duty cycle of the third wave signal SQR_R3 reflects the phase difference between SQR_R1 and SQR_R2.

[0056] In some embodiments, such as Figure 8As shown, the DC-DC converter circuit 106 includes: a third operational amplifier U6, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5. The first terminal of the seventeenth resistor R17 is used to input the third-order waveform signal SQR_R3. The second terminal of the seventeenth resistor R17 is connected to the first terminal of the third capacitor C3 and the first terminal of the eighteenth resistor R18. The second terminal of the eighteenth resistor R18 is connected to the first terminal of the nineteenth resistor R19 and the first terminal of the fifth capacitor C5. The second terminal of the nineteenth resistor R19 is connected to the non-inverting input of the third operational amplifier U6 and the first terminal of the fourth capacitor C4. The second terminal of the fourth capacitor C4 is grounded. The second terminal of the fifth capacitor C5 is connected to the output terminal of the third operational amplifier U5. The inverting input of the third operational amplifier U5 is connected to the output terminal of the third operational amplifier U5. The output terminal of the third operational amplifier U5 is used to output a DC voltage.

[0057] Specifically, the input signal SQR_R3 is a square wave with a certain duty cycle D. After passing through a passive low-pass filter with R17 and C3, a triangular wave related to D is obtained. The magnitude of this triangular wave's fluctuation is determined by the values ​​of R17 and C3, and its DC component is related to D. This fluctuating triangular wave, after passing through a second-order low-pass active filter composed of an operational amplifier, resistors, and capacitors, yields a DC voltage with minimal fluctuation. The fluctuation is determined by the values ​​of C4, C5, R18, and R19.

[0058] In summary, the phase difference measurement device for drilling resistivity measurement according to the embodiments of the present invention has a wide adjustment range, excellent anti-interference ability and higher stability.

[0059] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0061] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0064] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A phase difference measuring device for measuring resistivity while drilling, characterized in that, The device includes: a first automatic gain control circuit, a second automatic gain control circuit, a waveform conversion circuit, a duty cycle calculation circuit, and a DC-DC conversion circuit; The first automatic gain control circuit is used to automatically adjust the gain of the first electromagnetic wave signal to obtain a first adjustment signal, and the second automatic gain control circuit is used to automatically adjust the gain of the second electromagnetic wave signal to obtain a second adjustment signal. The first electromagnetic wave signal and the second electromagnetic wave signal both contain the measured stratum information, and the difference between the amplitude of the first adjustment signal and the amplitude of the second adjustment signal is less than a preset difference. The waveform conversion circuit is used to convert the first adjustment signal and the second adjustment signal into waveforms respectively, so as to obtain a first square wave signal and a second square wave signal with the same duty cycle and frequency. The duty cycle calculation circuit is used to obtain a third square wave signal based on the first square wave signal and the second square wave signal, wherein the duty cycle of the third square wave signal is the phase difference between the first square wave signal and the second square wave signal; The DC-to-DC converter circuit is used to obtain a DC voltage based on the third wave signal, wherein the DC voltage is used to obtain the drilling resistivity; The duty cycle calculation circuit includes: a first D flip-flop, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, and a sixteenth resistor. The first end of the eleventh resistor R11 is connected to a first preset power supply, and the second end of the eleventh resistor is connected to the first set pin of the first D flip-flop. The first end of the twelfth resistor is connected to a second preset power supply, and the second end of the twelfth resistor is connected to the first data input pin of the first D flip-flop. The first end of the thirteenth resistor is used to input the first square wave signal, and the second end of the thirteenth resistor is connected to the first clock pin of the first D flip-flop. The first end of the fourteenth resistor is connected to a third preset power supply, and the second end of the fourteenth resistor is connected to the second set pin of the first D flip-flop. The first end of the fifteenth resistor is connected to a fourth preset power supply, and the second end of the fifteenth resistor is connected to the second data input pin of the first D flip-flop. The first end of the sixteenth resistor is used to input the second square wave signal, and the second end of the sixteenth resistor is connected to the second clock pin of the first D flip-flop. The first reset pin of the first D flip-flop is connected to the second output pin, and the first output pin of the first D flip-flop is connected to the second reset pin, and is used to output the third square wave signal.

2. The phase difference measuring device for measuring resistivity while drilling according to claim 1, characterized in that, Both the first electromagnetic wave signal and the second electromagnetic wave signal are sinusoidal signals. The first automatic gain control circuit and the second automatic gain control circuit have the same structure. The first automatic gain control circuit includes a transconductance amplifier circuit, a signal conditioning circuit, and an integrator circuit. The input terminal of the transconductance amplifier circuit is used to input the first electromagnetic wave signal. The output terminal of the transconductance amplifier circuit is connected to the input terminal of the signal conditioning circuit. The control terminal of the transconductance amplifier circuit is connected to the output terminal of the integrator circuit. The first output terminal of the signal conditioning circuit is connected to the waveform conversion circuit. The second output terminal of the signal conditioning circuit is connected to the input terminal of the integrator circuit. The transconductance amplifier circuit is used to adjust its own amplification factor according to the control signal output by the integrator circuit, and amplify the first electromagnetic wave signal based on the amplification factor. The signal conditioning circuit is used to rectify the amplified first electromagnetic wave signal, and the integrator circuit is used to integrate the rectified first electromagnetic wave signal to obtain the control signal.

3. The phase difference measuring device for measuring resistivity while drilling according to claim 2, characterized in that, The transconductance amplifier circuit includes a transconductance amplifier, a first resistor, a second resistor, and a third resistor. The first terminal of the first resistor is connected to the non-inverting input of the transconductance amplifier and is used to input the first electromagnetic wave signal. The second terminal of the first resistor is grounded. The first terminal of the second resistor is connected to the inverting input of the transconductance amplifier and the first terminal of the third resistor, respectively. The second terminal of the second resistor is grounded. The second terminal of the third resistor is connected to the output terminal of the transconductance amplifier. The output terminal of the transconductance amplifier is connected to the input terminal of the signal conditioning circuit. The control terminal of the transconductance amplifier is connected to the output terminal of the integrator circuit.

4. The phase difference measuring device for measuring resistivity while drilling according to claim 2, characterized in that, The signal conditioning circuit includes: a first operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first diode, and a second diode. The first terminal of the fourth resistor is connected to the non-inverting input of the first operational amplifier, and the second terminal of the fourth resistor is grounded. The first terminal of the fifth resistor is connected to the output terminal of the transconductance amplifier circuit and the first terminal of the eighth resistor. The second terminal of the fifth resistor is connected to the inverting input of the first operational amplifier and the first terminal of the sixth resistor. The second terminal of the sixth resistor is connected to the output terminal of the first operational amplifier and the first terminal of the seventh resistor. The second terminal of the seventh resistor is connected to the anode of the first diode, and the second terminal of the eighth resistor is connected to the anode of the second diode. Wherein, the output terminal of the first operational amplifier serves as the first output terminal of the signal conditioning circuit, and the cathode of the first diode is connected to the cathode of the second diode, serving as the second output terminal of the signal conditioning circuit.

5. The phase difference measuring device for measuring resistivity while drilling according to claim 2, characterized in that, The integrating circuit includes: a second operational amplifier, a ninth resistor, a tenth resistor, a first capacitor, and a second capacitor. The first end of the ninth resistor is connected to the second output terminal of the signal conditioning circuit and the inverting input of the second operational amplifier. The second end of the ninth resistor is connected to the first end of the tenth resistor. The second end of the tenth resistor is connected to the output terminal of the second operational amplifier. The non-inverting input of the second operational amplifier is grounded. The first capacitor is connected in parallel with the ninth resistor, and the second capacitor is connected in parallel with the tenth resistor. The output terminal of the second operational amplifier serves as the output terminal of the integrating circuit.

6. The phase difference measuring device for measuring resistivity while drilling according to claim 1, characterized in that, The waveform conversion circuit includes: a first comparator and a second comparator. The non-inverting input of the first comparator is connected to the output of the first automatic gain control circuit, the inverting input of the first comparator is grounded, and the output of the first comparator outputs the first square wave signal. The non-inverting input of the second comparator is connected to the output of the second automatic gain control circuit, the inverting input of the second comparator is grounded, and the output of the second comparator outputs the second square wave signal.

7. The phase difference measuring device for measuring resistivity while drilling according to claim 1, characterized in that, The DC-DC converter circuit includes: a third operational amplifier, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a third capacitor, a fourth capacitor, and a fifth capacitor. The first terminal of the seventeenth resistor is used to input the third wave signal. The second terminal of the seventeenth resistor is connected to the first terminal of the third capacitor and the first terminal of the eighteenth resistor. The second terminal of the eighteenth resistor is connected to the first terminal of the nineteenth resistor and the first terminal of the fifth capacitor. The second terminal of the nineteenth resistor is connected to the non-inverting input of the third operational amplifier and the first terminal of the fourth capacitor. The second terminal of the fourth capacitor is grounded. The second terminal of the fifth capacitor is connected to the output terminal of the third operational amplifier. The inverting input of the third operational amplifier is connected to the output terminal of the third operational amplifier. The output terminal of the third operational amplifier is used to output the DC voltage.

8. The phase difference measuring device for measuring resistivity while drilling according to claim 3, characterized in that, The resistance value of the first resistor is in the range of 20kΩ-47kΩ.

9. The phase difference measuring device for measuring resistivity while drilling according to claim 5, characterized in that, The capacitance values ​​of the first capacitor and the second capacitor range from 47nF to 100nF.

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