Downhole main control board and method for judging drilling state of downhole tool

Abstract

The invention discloses an underground main control board and an underground tool drilling state judgment method, when the underground main control board is used, the main control board goes down a well along with a drilling tool, and the main control board comprises an MCU, and a gyroscope, a triaxial accelerometer, a memory, a clock unit and a directional sensor which are electrically connected with the MCU, the MCU measures the rotating speed of the drilling tool through the gyroscope, monitors the vibration condition of the drilling tool through the three-axis accelerometer, saves data in real time through the clock unit and the storage, obtains data of the directional sensor and further can receive rotating speed signals of the turbine generator. The underground main control board disclosed by the invention is low in cost and simple in structure, can be used for a long time in an underground complex environment, and can be matched with the method disclosed by the invention to accurately judge the drilling state of an underground tool.

Description

Technical Field

[0001] The invention belongs to the field of logging while drilling, and in particular relates to a downhole main control board and a method for judging the drilling state of a downhole tool in the field. Background Art

[0002] During the construction of logging while drilling, there are many drilling states for downhole tools, such as tripping, rotary drilling, sliding drilling, and composite drilling. In order to obtain ideal measurement data, the working state of the logging while drilling instrument should match the working state of the drill bit. First, during the process of lifting and lowering or tripping, no measurement data is needed and the instrument can stop working, which can save power consumption for battery-powered instruments; second, when the instrument is in the rotating state and the sliding state (directional stage), the ground directional engineers pay attention to different measurement data. If different measurement data can be uploaded according to the drilling state, the intelligent operation of the instrument can be realized and the effective data transmission rate can be improved; third, in order to ensure the accuracy of the measurement data during the instrument inclination measurement, the instrument needs to perform static measurement and send static inclination measurement data. Therefore, correctly identifying the downhole drilling state is of great significance to controlling downhole instruments.

[0003] At present, there are two main technologies for identifying downhole drilling status. One is to install an accelerometer in the downhole instrument, measure and calculate the acceleration value, and compare it with the preset threshold value to determine whether to start or stop the pump. The other is to install a pressure sensor in the downhole instrument and measure the change in pressure value to determine whether to start or stop the pump. However, when the pump is turned on, the current drilling status may be circulating, compound or sliding drilling. In other words, it is impossible to distinguish whether it is compound drilling or sliding drilling by judging whether to start or stop the pump, and it is impossible to accurately control the working status of the downhole instrument. Therefore, in order to better control the working status of the measurement while drilling instrument, a better drilling status judgment method is needed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a downhole main control board and a method for judging the drilling status of downhole tools.

[0005] The present invention adopts the following technical solution: A downhole main control board is lowered into the well along with a drilling tool when in use. The improvement thereof is that it comprises an MCU and a gyroscope electrically connected to the MCU, a three-axis accelerometer, a memory, a clock unit and a directional sensor. The MCU measures the rotation speed of the drilling tool by using the gyroscope, monitors the vibration of the drilling tool by using the three-axis accelerometer, saves data in real time by using the clock unit and the memory, and obtains the directional sensor data. In addition, the MCU can also receive the rotation speed signal of a turbine generator.

[0006] Furthermore, the DC voltage signal output by the gyroscope is input into the 16-bit ADC chip integrated in the MCU through the signal conditioning circuit for sampling and conversion.

[0007] Furthermore, the signal conditioning circuit is a low-pass filter and voltage range conversion circuit, which specifically includes an operational amplifier. The DC voltage signal output by the gyroscope is input into the negative input terminal of the operational amplifier through resistor R12. The positive input terminal of the operational amplifier is electrically connected to resistor R17, resistor R19 and capacitor C24 respectively. Resistor R17 is connected to a 5V power supply, resistor R19 and capacitor C24 are grounded, the V+ port of the operational amplifier is connected to a 5V power supply, one end of capacitor C19 is grounded, and the other end is electrically connected to the V+ port of the operational amplifier, the V- port of the operational amplifier is grounded, the output terminal of the operational amplifier is electrically connected to the 16-bit ADC chip integrated in the MCU, and after capacitor C20 and resistor R10 are connected in parallel, one end is electrically connected to the negative input terminal of the operational amplifier, and the other end is electrically connected to the output terminal of the operational amplifier.

[0008] Furthermore, the MCU is also electrically connected to the RS485 transceiver and the bus voltage detection circuit.

[0009] Furthermore, the MCU is powered by a low dropout linear regulator.

[0010] Furthermore, the MCU can also generate coded pulse drive signals.

[0011] Furthermore, the memory is a serial FLASH memory.

[0012] A method for judging the drilling status of a downhole tool, using the downhole main control board, has the following improvements: When the drilling tool is powered by a turbine generator: If the MCU detects that the turbine generator has no speed, the gyroscope has no output, and the vibration of the drill bit monitored by the three-axis accelerometer is lower than the set threshold, the drill bit is in the state of drilling up or drilling down; If the turbine generator speed detected by the MCU, the gyroscope output, and the drilling tool vibration monitored by the three-axis accelerometer all exceed the set threshold, the drilling tool is in a rotating state; If the turbine generator speed detected by the MCU and the drilling tool vibration monitored by the three-axis accelerometer exceed the set threshold, and the gyroscope output is lower than the set threshold, the drilling tool is in a sliding state; If the turbine generator speed detected by the MCU, the gyroscope output, and the drilling tool vibration monitored by the three-axis accelerometer are all lower than the set threshold, the drilling tool is in a stationary state; When the drilling tool is powered by batteries, other judgment conditions remain unchanged except that the turbine generator speed is no longer considered.

[0013] The beneficial effects of the present invention are: The downhole main control board disclosed in the present invention has low cost and simple structure, can be used for a long time in complex downhole environments, and can accurately judge the drilling status of downhole tools in conjunction with the method of the present invention.

[0014] The method disclosed in the present invention uses a gyroscope to measure the rotation speed of the drill tool, uses a three-axis accelerometer to monitor the vibration of the drill tool, and then obtains the rotation speed of the turbine generator. Through the combination of these three parameters, the current drilling state of the downhole tool is judged. The judgment result has high reliability and low misjudgment rate, and is particularly suitable as a basis for controlling the working state of the downhole measurement instrument to increase the working time of the downhole instrument. Therefore, the method of the present invention has a high practical value for controlling the working state of downhole instruments in the downhole measurement system in the oil field, mining and other industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the circuit diagram of the downhole main control board; Figure 2 is a schematic diagram of the signal conditioning circuit. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] Embodiment 1, this embodiment discloses A downhole main control panel, which is lowered into the well along with the drilling tool when in use. Figure 1 As shown, it includes an MCU and a gyroscope electrically connected to the MCU, a three-axis accelerometer, a memory, a clock unit and an directional sensor. The MCU uses the gyroscope to measure the rotation speed of the drill tool, uses the three-axis accelerometer to monitor the vibration of the drill tool, uses the clock unit and the memory to save data in real time, and obtains the directional sensor data. In addition, the MCU can also receive the rotation speed signal of the turbine generator. The MCU is also electrically connected to the RS485 transceiver and the bus voltage detection circuit. The MCU is powered by a low-voltage difference linear regulator. The MCU can also generate a coded pulse drive signal. The memory is a serial FLASH memory.

[0018] MCU collects and calculates the measurement values ​​of various sensors, and gives the drilling status of the downhole tool after calculation and judgment. The gyroscope is used to measure the rotation speed of the drill bit. Setting a certain threshold value can directly reflect whether the downhole tool is rotating or sliding. It can also calculate the stick-slip level of the downhole tool based on this, indirectly reflect the stick-slip situation of the downhole tool, understand the status of the downhole tool, and ensure the safety of drilling construction. The three-axis accelerometer is used to monitor the vibration of the downhole tool. By reading the digital quantity output by the three-axis accelerometer, the vibration analog value is restored, the vibration level is obtained, and the appropriate threshold value is set. It can directly reflect whether the current downhole tool is dynamic or static. The digital output is used with high accuracy to avoid misjudgment caused by temperature. If the downhole instrument is powered by a turbine generator, the MCU can also collect the speed of the turbine generator, and the turbine generator speed can also be used as a parameter to judge the drilling status of the downhole tool. At the same time, the MCU can also collect the original data of the directional sensor in real time and calculate the engineering value; finally, all the measurement data and other short-section measurement data are packaged and encoded according to the set sequence and uploaded to the ground. It also integrates real-time clock and data storage functions, which can save a large number of collected engineering parameters and directional parameters in real time underground, and read them out after drilling to analyze underground working conditions or instrument failure causes.

[0019] In this embodiment, the DC voltage signal output by the gyroscope is input into the 16-bit ADC chip integrated in the MCU through the signal conditioning circuit for sampling and conversion.

[0020] like Figure 2 As shown, the signal conditioning circuit is a low-pass filter and voltage range conversion circuit, which specifically includes an operational amplifier. The DC voltage signal output by the gyroscope is input into the negative input terminal of the operational amplifier through a resistor R12. The positive input terminal of the operational amplifier is electrically connected to resistor R17, resistor R19 and capacitor C24 respectively. Resistor R17 is connected to a 5V power supply, resistor R19 and capacitor C24 are grounded, the V+ port of the operational amplifier is connected to a 5V power supply, one end of the capacitor C19 is grounded, and the other end is electrically connected to the V+ port of the operational amplifier, the V- port of the operational amplifier is grounded, the output terminal of the operational amplifier is electrically connected to the 16-bit ADC chip integrated in the MCU, and after capacitor C20 and resistor R10 are connected in parallel, one end is electrically connected to the negative input terminal of the operational amplifier, and the other end is electrically connected to the output terminal of the operational amplifier.

[0021] When the downhole main control board is the master node of the bus, it is responsible for realizing the workflow control of the entire downhole tool string, including collecting data from each sensor node, data encoding, generating coded drive signals, uploading different preset parameter sequences according to the detected switch pump status and tool rotation status, and storing necessary test data and communication error information. When the ground interface box is connected to the bus and applies to be the master node, the downhole main control board switches to the slave node mode and receives inquiries and configurations from the ground interface box.

[0022] The downhole main control board realizes the dynamic and static measurement of drilling tools, vibration intensity measurement, drilling tool speed measurement, turbine generator speed measurement, bus voltage measurement, directional sensor module data acquisition, and generation of coded pulse drive signals. At the same time, the downhole main control board integrates a hardware real-time clock and non-volatile memory, which can store specified measurement data and communication error information according to time index.

[0023] The power supply requirement for the underground main control board is a 5V DC power supply. Use LDO to convert 5V to 3.3V for use by digital circuits such as MCU. The analog sensor part is directly powered by 5V.

[0024] When the downhole tool is powered by a turbine generator, it is necessary to measure the turbine generator speed in real time. As one of the bases for judging the power source of the downhole tool, the downlink instruction decoding can also be realized through the turbine generator speed. The turbine generator speed signal is a square wave signal, and its frequency is proportional to the turbine generator speed. The turbine generator speed measurement range is 300rpm-6000rpm, and the corresponding square wave signal frequency is 10Hz-200Hz. The square wave signal frequency can be measured through the input capture timer function of the MCU.

[0025] This embodiment also discloses a method for determining the drilling status of a downhole tool, using the downhole main control board described above: When the drilling tool is powered by a turbine generator: If the MCU detects that the turbine generator has no speed, the gyroscope has no output, and the vibration of the drill bit monitored by the three-axis accelerometer is lower than the set threshold, the drill bit is in the state of drilling up or drilling down; In this state, the downhole tool vibrates weakly, is at the lowest vibration level, and can be powered off to save battery power.

[0026] If the turbine generator speed detected by the MCU, the gyroscope output, and the drilling tool vibration monitored by the three-axis accelerometer all exceed the set threshold, the drilling tool is in a rotating state; Dynamic measurement data that ground direction engineers are more concerned about can be sent according to the current status to reduce the occupancy rate of useless data on the channel.

[0027] If the turbine generator speed detected by the MCU and the drilling tool vibration monitored by the three-axis accelerometer exceed the set threshold, and the gyroscope output is lower than the set threshold, the drilling tool is in a sliding state; In this state, the downhole tool is in the directional stage and non-rotating state. It can send dynamic measurement data that the ground directional engineers are more concerned about according to the current state to reduce the occupancy rate of useless data on the channel.

[0028] If the turbine generator speed detected by the MCU, the gyroscope output, and the drilling tool vibration monitored by the three-axis accelerometer are all lower than the set threshold, the drilling tool is in a stationary state; During the inclination measurement process of the downhole tool, in order to ensure the measurement accuracy, the downhole tool needs to be in a stationary state, in which only the inclination measurement data is sent.

[0029] When the drilling tool is powered by batteries, other judgment conditions remain unchanged except that the turbine generator speed is no longer considered.

Claims

1. A downhole main control panel, which is lowered into the well along with the drilling tool when in use, and is characterized by: It includes an MCU and a gyroscope electrically connected to the MCU, a three-axis accelerometer, a memory, a clock unit and a directional sensor. The MCU uses the gyroscope to measure the rotation speed of the drill tool, uses the three-axis accelerometer to monitor the vibration of the drill tool, uses the clock unit and the memory to save data in real time, and obtains the directional sensor data. In addition, the MCU can also receive the rotation speed signal of the turbine generator.

2. The downhole main control board according to claim 1, characterized in that: The DC voltage signal output by the gyroscope is input into the 16-bit ADC chip integrated in the MCU through the signal conditioning circuit for sampling and conversion.

3. The downhole main control board according to claim 2, characterized in that: The signal conditioning circuit is a low-pass filter and voltage range conversion circuit, which specifically includes an operational amplifier. The DC voltage signal output by the gyroscope is input into the negative input terminal of the operational amplifier through a resistor R12. The positive input terminal of the operational amplifier is electrically connected to resistor R17, resistor R19 and capacitor C24 respectively. Resistor R17 is connected to a 5V power supply, resistor R19 and capacitor C24 are grounded, the V+ port of the operational amplifier is connected to a 5V power supply, one end of the capacitor C19 is grounded, and the other end is electrically connected to the V+ port of the operational amplifier, the V- port of the operational amplifier is grounded, the output terminal of the operational amplifier is electrically connected to the 16-bit ADC chip integrated in the MCU, and after capacitor C20 and resistor R10 are connected in parallel, one end is electrically connected to the negative input terminal of the operational amplifier, and the other end is electrically connected to the output terminal of the operational amplifier.

4. The downhole main control board according to claim 1, characterized in that: The MCU is also electrically connected to the RS485 transceiver and the bus voltage detection circuit.

5. The downhole main control board according to claim 1, characterized in that: The MCU is powered by a low dropout linear regulator.

6. The downhole main control board according to claim 1, characterized in that: MCU can also generate coded pulse drive signals.

7. The downhole main control board according to claim 1, characterized in that: The memory is a serial FLASH memory.

8. A method for judging the drilling status of a downhole tool, using the downhole main control board according to claim 1, characterized in that: When the drilling tool is powered by a turbine generator: If the MCU detects that the turbine generator has no speed, the gyroscope has no output, and the vibration of the drill bit monitored by the three-axis accelerometer is lower than the set threshold, the drill bit is in the state of drilling up or drilling down; If the turbine generator speed detected by the MCU, the gyroscope output, and the drilling tool vibration monitored by the three-axis accelerometer all exceed the set threshold, the drilling tool is in a rotating state; If the turbine generator speed detected by the MCU and the drilling tool vibration monitored by the three-axis accelerometer exceed the set threshold, and the gyroscope output is lower than the set threshold, the drilling tool is in a sliding state; If the turbine generator speed detected by the MCU, the gyroscope output, and the drilling tool vibration monitored by the three-axis accelerometer are all lower than the set threshold, the drilling tool is in a stationary state; When the drilling tool is powered by batteries, other judgment conditions remain unchanged except that the turbine generator speed is no longer considered.

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