Downhole temperature sensor processing module

Abstract

The utility model discloses an underground temperature sensor processing module which comprises a power supply circuit, a high-temperature high-precision voltage reference circuit and two temperature sensor processing channels, and each temperature sensor processing channel is composed of a pre-amplification circuit, a low-pass filter circuit and an output buffer circuit. According to the utility model, two paths of PT100 temperature sensors can be connected, stable and high-precision output can be provided in a wide temperature range, reliable temperature measurement can be provided even in a severe environment, and the performance change is small as time goes on; when the same temperature is measured again after the environmental condition is changed, a very consistent result can be provided; the device can work in a large temperature range, and the requirement of a logging instrument is completely met. The underground temperature sensor processing module has the characteristics of high measurement precision, good stability, good repeatability, electromagnetic interference resistance, long service life and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of petroleum well logging equipment, in particular to a downhole temperature sensor processing module. Background Art

[0002] Acoustic logging is an important logging method in geophysical logging. It uses the differences in acoustic properties such as speed, amplitude and frequency when sound waves propagate in different rocks to study the geological profile of the drilling and judge the quality of cementing. It is an important means of exploring and developing oil and gas fields.

[0003] In oil exploration and logging, logging instruments are lowered into boreholes thousands of meters deep. The temperature in the borehole gradually increases with depth. During the logging process, it is necessary to measure the ambient temperature in the borehole or the ambient temperature near a component in the logging instrument. Measuring ambient temperature in a borehole, also known as wellbore temperature measurement, is primarily used to study geological structures and rock formation properties, identify useful minerals, and inspect the technical status of the borehole. This requires high-precision temperature measurement. Furthermore, oil exploration and logging instruments must operate in boreholes thousands of meters deep, often subject to high temperatures and large pressure fluctuations, placing high demands on the stability and reliability of temperature sensors. Utility Model Content

[0004] In order to solve the above problem, the utility model provides a downhole temperature sensor processing module to solve the problem.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] A downhole temperature sensor processing module includes a power supply circuit, a high-temperature and high-precision voltage reference circuit, and two temperature sensor processing channels. The temperature sensor processing channels are composed of a preamplifier circuit, a low-pass filter circuit, and an output buffer circuit. The preamplifier circuit is provided with a bridge circuit.

[0007] It is further configured as follows: the power supply circuit is provided with power supply input ports, and the power supply input ports are respectively a positive power supply VS+, a negative power supply VS-, a low-voltage positive power supply VCC and AGND.

[0008] It is further configured as follows: the high-temperature and high-precision voltage reference circuit includes a voltage reference, the power supply voltage of the voltage reference is a +15V VDD power supply, and the reference voltage is connected to the bridge circuit in the preamplifier circuit.

[0009] It is further configured as follows: the preamplifier circuit of the temperature sensor processing channel includes PT1+ and PT1- input terminals, an instrumentation amplifier U1, and input pins G1A and G1B. The PT1+ and PT1- are connected to the instrumentation amplifier U1, and the input pins G1A and G1B are respectively connected to the gain adjustment terminals of the instrumentation amplifier U1.

[0010] It is further configured that: the preamplifier circuit is provided with a +2.5V power supply.

[0011] It is further configured as follows: the bridge circuit is composed of a resistor R1, a resistor R2, a resistor R3, a resistor R4 and an external temperature sensor PT100.

[0012] It is further configured as follows: the low-pass filter circuit includes PT1-A, PT1-A is connected to resistor R5; the other end of resistor R5 is connected to capacitor C1 and resistor R6, the other end of resistor R6 is connected to capacitor C2 and pin 3 of operational amplifier U3.1 (model OP2177ARMZ), and the other end of capacitor C1 is connected to pins 1 and 2 of operational amplifier U3.1; the resistor R5, resistor R6, capacitor C1, capacitor C2, and operational amplifier U3.1 form a second-order RC active low-pass filter.

[0013] It is further configured as follows: the output buffer circuit includes PT1-B, and PT1-B is connected to a resistor R18, the other end of the resistor R18 is respectively connected to a diode D1, a diode D2 and an operational amplifier U4.1, the resistor R18 is connected to pin 3 of the operational amplifier U4.1, and pins 2 and 1 of the operational amplifier U4.1 are connected.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are:

[0015] This utility model connects two PT100 temperature sensors and provides stable, high-precision output over a wide temperature range, making it commonly used in applications requiring precise temperature control. It delivers reliable temperature measurements even in harsh environments, with minimal performance change over time. It also provides highly consistent results when re-measuring the same temperature after changing environmental conditions. It operates over a wide temperature range, fully meeting the requirements of well logging instruments. The downhole temperature sensor processing module offers high measurement accuracy, excellent stability, repeatability, immunity to electromagnetic interference, and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic diagram of the circuit connection of the utility model;

[0018] Figure 2 This is a circuit diagram of the power supply circuit in the present utility model;

[0019] Figure 3 This is a circuit diagram of a high-temperature and high-precision voltage reference circuit of the utility model;

[0020] Figure 4 This is a circuit diagram of the preamplifier circuit in the present utility model;

[0021] Figure 5 This is a circuit diagram of a low-pass filter circuit in the utility model;

[0022] Figure 6 This is a circuit diagram of the output buffer circuit in the utility model. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0024] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances. Example

[0025] Reference Figure 1 , is a downhole temperature sensor processing module disclosed in the utility model, which includes a power supply circuit, a high-temperature and high-precision voltage reference circuit, and a temperature sensor processing channel in which the two circuits are completely consistent.

[0026] Reference Figure 2 The power supply circuit is provided with a power supply input port. Specifically, the power supply input ports are respectively a positive power supply VS+ (+15V), a negative power supply VS- (-15V), a low voltage positive power supply VCC (+3.3V) and AGND;

[0027] Among them, the positive power supply is connected to the resistor R16 from the VS+ input terminal, and then connected to the capacitor C8 and the capacitor C10 for filtering. The power supply circuit sets VDD as the power supply in the module. The negative power supply VS- input terminal is connected to the resistor R17 and then connected to the capacitor C9 and the capacitor C11 for filtering. VEE is the power supply in the module. The low-voltage positive power supply VCC input terminal is connected to the resistor R20 and then connected to the capacitor C12 and the capacitor C13 for filtering.

[0028] Reference Figure 3 The high-temperature and high-precision voltage reference circuit includes a voltage reference model REF5025SHKJ. In this embodiment, the voltage reference provides a high-precision, low-noise, and low-temperature drift 2.5V reference voltage source for the temperature sensor processing circuit.

[0029] The power supply voltage of the voltage reference is the +15V VDD power supply. The 2.5V reference voltage is connected to the bridge circuit in the preamplifier circuit.

[0030] Reference Figure 1 In this embodiment, the temperature sensor processing channel is composed of a preamplifier circuit, a low-pass filter circuit, and an output buffer circuit.

[0031] Reference Figure 4 Specifically, the preamplifier circuit of the temperature sensor processing channel includes PT1+ and PT1- input terminals, an instrumentation amplifier U1 of model AD8421ARZ connected to the PT1+ and PT1- input terminals, and also includes input pins G1A and G1B. The input pins G1A and G1B are respectively connected to the gain adjustment terminal (Rg) of the instrumentation amplifier U1, and an external resistor can be connected to adjust the amplifier gain.

[0032] The two temperature sensor signals are input through the PT1+ / PT1- input terminals. The instrumentation amplifier U1 amplifies the tiny temperature sensor signals. The two temperature sensor signals pass through the low-pass filter circuit and the output buffer circuit and output 0-3.3V sensor temperature voltage signals through the module output terminals TMEP1 and TEMP2 respectively.

[0033] Furthermore, the preamplifier circuit is provided with a +2.5V power supply, which is connected to the +2.5V output terminal of the voltage reference circuit. The +2.5V power supply serves as a precision reference power supply for the bridge circuit.

[0034] In this embodiment, the bridge circuit of the temperature sensor processing channel is composed of resistors R1, R2, R3, R4 and an external temperature sensor PT100;

[0035] The signals of the two temperature sensors after being processed by the preamplifier are input into the low-pass filter circuit through PT1-A respectively.

[0036] Reference Figure 5 In the low-pass filter circuit, PT1-A is connected to resistor R5; the other end of resistor R5 is connected to capacitor C1 and resistor R6, the other end of resistor R6 is connected to capacitor C2 and pin 3 of the operational amplifier U3.1 (model OP2177ARMZ), and the other end of capacitor C1 is connected to pins 1 and 2 of the operational amplifier U3.1;

[0037] In this embodiment, resistor R5, resistor R6, capacitor C1, capacitor C2, and operational amplifier U3.1 form a second-order RC active low-pass filter. The final output signal is output by pin 1 of the operational amplifier U3.1. Pin 1 of the operational amplifier U3.1 is connected to the output terminal PT1-B. The signal output by the filter is input to the output buffer circuit via PT1-B.

[0038] Reference Figure 6 In the output buffer circuit, PT1-B is connected to resistor R18. The other end of resistor R18 is connected to diode D1 and diode D2, both of which are 1N4148, and operational amplifier U4.1, which is AD8552. Specifically, resistor R18 is connected to pin 3 of operational amplifier U4.1.

[0039] In this embodiment, the diode D1 and the diode D2 function to limit the amplitude of the input PT1-B signal.

[0040] Pins 2 and 1 of the operational amplifier U4.1 are connected so that the operational amplifier U4 acts as a voltage follower, and the temperature sensor signal is finally brought out from the TEMP1 and TEMP2 output terminals.

[0041] The working principle and beneficial effects of the utility model are as follows:

[0042] The utility model has two PT100 temperature sensor processing circuits; an internal high-precision voltage reference source and an output buffer circuit, which outputs a 0-3.3V temperature voltage signal that can be sampled by an analog-to-digital converter in a microcontroller; and the overall temperature measurement error is less than ±0.1°C.

[0043] This utility model connects two PT100 temperature sensors, providing stable, high-precision output over a wide temperature range and is commonly used in applications requiring precise temperature control. It offers reliable temperature measurement even in harsh environments, with minimal performance change over time. It also provides highly consistent results when re-measuring the same temperature after changing environmental conditions. It operates over a wide temperature range, fully meeting the requirements of well logging instruments. The downhole temperature sensor processing module features high measurement accuracy, excellent stability, repeatability, immunity to electromagnetic interference, and a long service life.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole temperature sensor processing module, characterized in that: It includes a power supply circuit, a high-temperature and high-precision voltage reference circuit and two temperature sensor processing channels. The temperature sensor processing channel consists of a preamplifier circuit, a low-pass filter circuit and an output buffer circuit. A bridge circuit is provided in the preamplifier circuit. The high-temperature and high-precision voltage reference circuit includes a voltage reference. The power supply voltage of the voltage reference is a +15V VDD power supply. The voltage reference is connected to the bridge circuit in the preamplifier circuit. The preamplifier circuit of the temperature sensor processing channel includes PT1+ and PT1- input terminals, an instrumentation amplifier U1 and input pins G1A and G1B. The PT1+ and PT1- are connected to the instrumentation amplifier U1. The input pins G1A and G1B are respectively connected to the gain adjustment terminals of the instrumentation amplifier U1.

2. A downhole temperature sensor processing module according to claim 1, characterized in that: The power supply circuit is provided with power supply input ports, and the power supply input ports are respectively a positive power supply VS+, a negative power supply VS-, a low voltage positive power supply VCC and AGND.

3. A downhole temperature sensor processing module according to claim 2, characterized in that: The preamplifier circuit is provided with a +2.5V power supply.

4. A downhole temperature sensor processing module according to claim 3, characterized in that: The bridge circuit is composed of a resistor R1, a resistor R2, a resistor R3, a resistor R4 and an external temperature sensor PT100.

5. A downhole temperature sensor processing module according to claim 4, characterized in that: The low-pass filter circuit includes PT1-A, PT1-A is connected to resistor R5; the other end of resistor R5 is connected to capacitor C1 and resistor R6, the other end of resistor R6 is connected to capacitor C2 and pin 3 of operational amplifier U3.1 (model OP2177ARMZ), and the other end of capacitor C1 is connected to pins 1 and 2 of operational amplifier U3.1; the resistor R5, resistor R6, capacitor C1, capacitor C2, and operational amplifier U3.1 form a second-order RC active low-pass filter.

6. A downhole temperature sensor processing module according to claim 5, characterized in that: The output buffer circuit includes PT1-B, and PT1-B is connected to resistor R18. The other end of resistor R18 is respectively connected to diode D1, diode D2 and operational amplifier U4.

1. The resistor R18 is connected to pin 3 of the operational amplifier U4.1, and pins 2 and 1 of the operational amplifier U4.1 are connected.

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