A method and system for automatic switching of downhole power supply and time delay power off in logging while drilling

Abstract

This invention discloses a method and system for automatic power switching and delayed power-off in logging-while-drilling, comprising: detecting the power supply status of a turbine generator and obtaining a status judgment result; when the status judgment result indicates a power supply status, controlling the turbine generator to supply power to the load and discharging energy from the energy storage element; when the status judgment result indicates a power-off status, controlling the battery to supply power to the load and starting a timer based on the charging process of the energy storage element; when the timer reaches a preset threshold, obtaining a power-off trigger signal and cutting off the battery's power supply to the load. This invention uses discrete analog devices to achieve automatic power switching and delayed power-off, eliminating the need for control chips and complex peripheral circuits.

Description

Technical Field

[0001] This invention belongs to the field of logging while drilling technology, and particularly relates to a method and system for automatic switching and delayed power cut-off of downhole power during logging while drilling. Background Technology

[0002] In logging while drilling (MWD), the MWD instrument is a core device for directional drilling and geosteering. Its attitude measurement probe (accelerometer and magnetometer) needs to acquire static data in a vibration-free environment to ensure the accuracy of parameters such as well inclination and azimuth. Therefore, in actual drilling operations, static measurements are typically performed during periods of pump and drilling shutdown. During this time, the turbine generator stops supplying power, requiring a backup battery downhole to power the attitude measurement probe. To achieve this, existing solutions typically incorporate dual power supplies—a turbine generator and a battery—in the MWD instrument. After a generator failure, the system automatically switches to battery power, disconnects the battery after a delay to conserve energy, and resumes power from the generator upon pump restart.

[0003] To address the aforementioned power switching and delayed power-off requirements, traditional solutions employ dedicated control chips (such as MCUs or power management chips) to monitor the turbine generator voltage in real time. Upon detecting a power outage, the control switch switches to battery power. Simultaneously, an internal timer or external crystal oscillator counts the delay, and battery power is cut off after a preset time. To achieve this function, traditional solutions require not only the control chip but also peripheral circuits such as a DC-DC power supply unit, crystal oscillator, and reset circuit, resulting in a complex overall design with numerous components and high cost. More importantly, the downhole working environment demands that electronic components withstand temperatures up to 175°C, a requirement that most dedicated control chips and their peripheral circuits cannot meet, making selection extremely difficult. Furthermore, the control chip and its peripheral circuits in traditional solutions require continuous power supply in standby mode, which consumes additional battery energy and shortens the battery's effective lifespan. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method and system for automatic switching and delayed power cut-off of downhole power during logging-while-drilling.

[0005] One method for automatically switching and delaying power off downhole power during logging-while-drilling includes: Detect the power supply status of the turbine generator and obtain the status judgment result; When the state determination result indicates a power supply state, the turbine generator is controlled to supply power to the load, and the energy storage element is allowed to release energy. When the state determination result indicates a power outage, control the power supply from the battery to the load and start timing based on the charging process of the energy storage element; When the timer reaches a preset threshold, a power-off trigger signal is received, cutting off the battery's power supply to the load.

[0006] Preferably, the process of detecting the power supply status of the turbine generator and obtaining the status judgment result includes: The gate-source voltage of the PMOS transistor automatically responds to the voltage changes of the turbine generator to distinguish between the power supply state and the power outage state.

[0007] Preferably, the process of releasing energy from the energy storage element includes: When the turbine generator is in the power supply state, the NMOS transistor is turned on, so that the energy storage element releases the stored energy through the discharge resistor.

[0008] Preferably, the process of controlling the supply of power from the battery to the load and initiating timing based on the charging process of the energy storage element includes: When the turbine generator is in the power-off state, the first PMOS transistor is turned on to connect the battery to the load, and the second PMOS transistor is turned on to enable the energy storage element to start charging through the charging resistor, thereby starting the timing.

[0009] Preferably, the process of cutting off the battery's power supply to the load when the timer reaches a preset threshold and a power-off trigger signal is obtained includes: When the voltage of the energy storage element during the charging process reaches a level that causes the gate-source voltage of the third PMOS transistor to fall below the turn-on threshold, the third PMOS transistor automatically turns off, thereby cutting off the power supply from the battery to the load.

[0010] Preferably, the gate of the third PMOS transistor is connected to the common node of the energy storage element and the charging resistor, and the voltage of the energy storage element serves as the control signal for the third PMOS transistor.

[0011] Preferably, the method further includes: providing a zero-voltage reference for the gate of the relevant PMOS transistor when the turbine generator is in the power-off state by setting a pull-down resistor, so as to ensure that the relevant PMOS transistor is turned on normally.

[0012] Preferably, the method is executed only by a circuit composed of discrete analog components, and it is not necessary to continuously supply power to the control circuit after the turbine generator is powered off; The discrete analog components include diodes, resistors, capacitors, and MOSFETs, and the temperature rating of the discrete analog components is at least 175°C.

[0013] Preferably, the power outage delay time corresponding to the preset threshold is set by adjusting the capacitance value of the energy storage element or the resistance value of the charging resistor.

[0014] The present invention also provides a system for automatic switching and delayed power cut-off of downhole power during logging-while-drilling, comprising: The voltage monitoring module is used to monitor the output voltage of the turbine generator and obtain voltage status signals; The switching control module is used to couple the turbine generator to the load when the voltage status signal indicates that there is voltage, and to couple the battery to the load when the voltage status signal indicates that there is no voltage, so as to obtain the power supply switching result; The delay module is used to charge the energy storage element when the power supply switching result is battery power, so as to obtain a gradually rising charging voltage signal. The power-off execution module is used to disconnect the connection between the battery and the load when the charging voltage signal reaches a preset threshold, thereby obtaining a power-off state.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention eliminates the need for dedicated control chips and complex peripheral circuits. It can achieve automatic power switching and delayed power-off functions using only discrete analog devices (diodes, resistors, capacitors, and MOSFETs), completely eliminating the need for control chips, crystal oscillators, reset circuits, and DC-DC power supply units. This significantly simplifies circuit design and reduces material costs and development difficulty.

[0016] The solution of this invention can meet the working environment of 175℃ in wells. All selected discrete analog devices are capable of withstanding 175℃ high temperature, which overcomes the bottleneck of the control chip and peripheral circuit in traditional solutions that are difficult to withstand high temperature, and improves the reliability and environmental adaptability of downhole electronic instruments.

[0017] This invention significantly reduces battery consumption during non-operational periods. When the turbine generator is supplying power normally, there is no need to continuously power the control circuit. After a delayed power-off, the entire circuit automatically enters a completely power-off state until the generator resumes power supply. Compared to the standby mode where the control chip is always powered in traditional solutions, this invention effectively reduces unnecessary battery energy loss and extends the effective operating time of both the battery and the instrument.

[0018] The delay time of this invention is flexibly adjustable. The delay time can be easily changed by simply adjusting the resistance and capacitance values ​​in the RC charging circuit without modifying the program or replacing the chip. It is simple to implement in engineering and has high stability. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1This is a circuit schematic diagram of an embodiment of the present invention; Figure 2 This is a Multisim simulation diagram of an embodiment of the present invention; Figure 3 Simulation diagram of the turbine generator supplying power according to an embodiment of the present invention; Figure 4 This is a simulation diagram of the turbine generator when it is powered off, according to an embodiment of the present invention. Figure 5 This is a simulation diagram of the entire system when the power is off, according to an embodiment of the present invention. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0022] Example 1 like Figure 1 As shown in the figure, this embodiment provides a method for automatic switching and delayed power cut-off of downhole power during logging-while-drilling, including: Detect the power supply status of the turbine generator and obtain the status judgment result; When the status judgment result indicates a power supply status, the control switches from turbine generator to power supply to the load and releases energy from the energy storage element. When the status judgment result is a power outage state, the control switches to supply power to the load from the battery and starts timing based on the charging process of the energy storage element. When the timer reaches the preset threshold, a power-off trigger signal is received, cutting off the battery's power supply to the load.

[0023] Furthermore, the process of detecting the power supply status of the turbine generator and obtaining the status judgment result includes: The gate-source voltage of the PMOS transistor automatically responds to the voltage changes of the turbine generator to distinguish between the power supply state and the power outage state.

[0024] Furthermore, the process of releasing energy from energy storage components includes: When the turbine generator is in power supply mode, the control NMOS transistor is turned on, so that the energy storage element releases the stored energy through the discharge resistor.

[0025] Furthermore, the process of controlling the supply of power from the battery to the load and initiating timing based on the charging process of the energy storage element includes: When the turbine generator is de-energized, the first PMOS transistor is turned on to connect the battery to the load, and the second PMOS transistor is turned on to enable the energy storage element to start charging through the charging resistor, thereby starting the timing.

[0026] Furthermore, when the timing reaches a preset threshold, a power-off trigger signal is received, and the process of cutting off the battery's power supply to the load includes: When the voltage of the energy storage element during the charging process reaches a level that causes the gate-source voltage of the third PMOS transistor to fall below the turn-on threshold, the third PMOS transistor automatically turns off, thereby cutting off the battery's power supply to the load.

[0027] Furthermore, the gate of the third PMOS transistor is connected to the common node of the energy storage element and the charging resistor, and the voltage of the energy storage element serves as the control signal for the third PMOS transistor.

[0028] Furthermore, the method also includes: providing a zero-voltage reference to the gate of the relevant PMOS transistor when the turbine generator is in a power-off state by setting a pull-down resistor, so as to ensure that the relevant PMOS transistor is turned on normally.

[0029] Furthermore, the method is executed only by a circuit composed of discrete analog components, and there is no need to continuously supply power to the control circuit after the turbine generator is powered off. Discrete analog components include diodes, resistors, capacitors, and MOSFETs, and the temperature rating of discrete analog components must be at least 175°C.

[0030] Furthermore, the power outage delay time corresponding to the preset threshold is set by adjusting the capacitance value of the energy storage element or the resistance value of the charging resistor.

[0031] As a preferred implementation method, the circuit designed in this embodiment is as follows: Figure 1 As shown, D1, D2, R3, Q2, and Q3 form an automatic power switching circuit, which enables the battery to automatically supply power to the system after the generator fails; Q1, R5, and C1 form a delayed power-off circuit, which controls the charging time of C1 to achieve the function of delayed power-off of the system; Q4, R1, R4, and R7 form a capacitor discharge circuit, which is used to discharge the energy of capacitor C1 when the generator is supplying power.

[0032] The circuit in this embodiment operates as follows: When the turbine generator is supplying power normally, the Vt of PMOS transistor Q3... gs =5V, Q3 is not conducting. At this time, the 33V voltage generated by the turbine generator supplies power to the load through diode D1, and diode D2 is reverse-biased and cut off. At the same time, the V of PMOS transistor Q1 is... gs=5V, Q1 is not conducting, C1 cannot be charged through R5, while NMOS transistor Q4 is conducting, and C1 discharges through Q4 and R4. This prevents C1 from having a non-zero voltage due to insufficient discharge, which would affect the delayed power-off time. When the pump stops, the turbine generator is de-energized, and at this time, V of Q3... gs =-28V, Q3 is on, Q2's V gs =-28V, Q2 conducts, and the battery supplies power to the load through Q3, Q2, and D2. Simultaneously, Q1 conducts, Q4 is not conducting, and capacitor C1 charges through Q1 and R5. The voltage across C1 gradually increases until it reaches the voltage across Q2. gs With a voltage of -4V, Q2 stops conducting, the battery cannot supply power to the load, and the entire system loses power until the turbine generator supplies power again.

[0033] Specifically, for Figure 1 The selection and value of all components are explained as follows: D1, D2: Diodes D1 and D2 are used to prevent series connection between the two power supplies. When selecting them, the reverse breakdown voltage should be greater than the power supply voltage, and the forward conduction voltage drop should be as small as possible. Based on the actual application scenario, FDLL914 is selected in this embodiment, which meets the above requirements and has a temperature resistance of 175℃. Q1, Q2, and Q3: These three MOSFETs are all P-channel MOSFETs. According to the usage scenario in this embodiment, Vt is applied across Q1, Q2, and Q3. gs The maximum value is -28V, therefore the selected model must meet this condition, and the model chosen is FQP15P12, V gs The maximum value is ±30V, which meets the requirements, and V ds Maximum voltage -120V, temperature resistance 175℃; Q4, R1, R4, R7: Q4 is mainly used to ensure that capacitor C1 can quickly discharge through R4 when the turbine generator is powered on. An N-channel MOSFET is selected, and its V0 gs By adjusting R7 and R1, the value of R4 determines the discharge time of capacitor C1. Q4 is selected as SQ3426EV, and its V... ds Maximum 60V, V gs The maximum value is 20V. Based on the on-state voltage, R1=R7=100kΩ. gs It is 16.5V, which meets the V requirement. gs (th) > 2V conduction condition, R4 must meet the discharge speed while ensuring that the discharge current meets the resistance power requirement. In this embodiment, R4 = 3.5kΩ; R5, C1: The timeout period is calculated using the charging circuit consisting of R5 and C1. U s The battery voltage is 28V, U cThe charging voltage is when U c When the voltage is >26V, the calculated t is the theoretical value of the power-off time. The power-off delay time can be set by adjusting the values ​​of R5 and C1. The specific time value should be based on actual measurement. In this embodiment, according to actual needs, C1=330uf, whose withstand voltage is 45V at 200℃, and R5=500k. The actual circuit was built and measured, and the power-off delay time was 6 minutes and 50 seconds.

[0034] R3: The function of R3 is to provide a reference ground and ensure that the gate voltage of Q1 and Q3 is 0V after the turbine generator is powered off. In this embodiment, R3 is set to 10kΩ.

[0035] This embodiment does not require monitoring of the turbine generator's voltage; the turbine generator automatically switches to battery voltage after power failure.

[0036] This embodiment adjusts the system power-off time based on the RC charging time, without the need for a dedicated power management chip or a small MCU. It is implemented through programming, making the design simple and reliable.

[0037] The circuit designed in this embodiment does not require continuous power supply, thus reducing battery consumption during non-working hours.

[0038] The components used in this embodiment are simple and low in cost, and can operate at a high temperature of 175°C, while dedicated power management chips or small MCUs are difficult to operate normally at 175°C.

[0039] As an additional implementation method, the circuit for automatic power switching and delayed power-off in this embodiment was simulated using Multisim. The simulation circuit is as follows: Figure 2 As shown, due to the limited component library of the simulation software, the MOSFET selected in this embodiment is not available. Therefore, other models are used instead, and the voltage is reduced for simulation. VCC1 represents the turbine generator, VCC0 represents the battery, and R6 simulates the load. The circuit function is verified through simulation.

[0040] Figure 3 This indicates that when the turbine generator supplies power to the load, Q3 is disconnected, the battery does not supply power to the load, Q4 is turned on, and capacitor C1 discharges until the voltage across its terminals is close to 0V, which is consistent with the design.

[0041] Figure 4 and Figure 5 This indicates that when the turbine generator is de-energized, Q3 conducts, the battery supplies power to the load, Q1 conducts, Q4 does not conduct, capacitor C1 begins to charge, and the voltage across its terminals gradually increases until it reaches 8.51V. The voltage across Q2... gsWhen the voltage is below its turn-on voltage, Q2 does not conduct, the battery stops supplying power to the load, the entire system is powered off, and it waits for the turbine generator to start again. The entire process is consistent with the design.

[0042] Example 2 Based on the same inventive concept, this embodiment also provides a system for automatic switching and delayed power cut-off of downhole power during logging-while-drilling, comprising: The voltage monitoring module is used to monitor the output voltage of the turbine generator and obtain voltage status signals; The switching control module is used to couple the turbine generator to the load when the voltage status signal indicates that there is voltage, and to couple the battery to the load when the voltage status signal indicates that there is no voltage, so as to obtain the power supply switching result. The delay module is used to charge the energy storage element when the power supply switch result is battery power, and obtain a gradually rising charging voltage signal. The power-off execution module is used to disconnect the battery from the load and obtain a power-off state when the charging voltage signal reaches a preset threshold.

[0043] Furthermore, the switching control module includes: The first PMOS transistor is used to connect its source to the output terminal of the turbine generator, its drain to the load, and to receive a voltage status signal at its gate to obtain a first switching state. The second PMOS transistor is used to connect its source to the positive terminal of the battery, its drain to the load via a diode, and to receive a voltage state signal at its gate to obtain a second switching state; and The first diode is used to connect its anode to the output terminal of the turbine generator and its cathode to the load, providing a path for the turbine generator to supply power to the load when the first PMOS transistor is turned off.

[0044] Furthermore, the voltage monitoring module includes a third PMOS transistor, which is used to connect its gate to the output terminal of the turbine generator, ground its source, and use its drain as the output terminal of the voltage status signal to drive the gates of the first PMOS transistor and the second PMOS transistor.

[0045] Furthermore, the delay module includes: A charging resistor is used to connect its first end to the positive terminal of the battery to obtain charging current. The energy storage element is a capacitor, with its first end connected to the second end of the charging resistor and its second end grounded. Under the action of the charging current, the voltage across the two ends gradually increases, thus obtaining the charging voltage signal.

[0046] Furthermore, the power-off execution module includes a fourth PMOS transistor. The fourth PMOS transistor is used to connect its source to the positive terminal of the battery, its drain to the branch in the switching control module that supplies power from the battery to the load, and its gate to the common node of the charging resistor and capacitor. When the voltage of the common node reaches the turn-off threshold of the fourth PMOS transistor, the fourth PMOS transistor is turned off, disconnecting the power supply from the battery to the load.

[0047] Furthermore, it also includes a discharge module, which is used to discharge the energy storage element to obtain a zero initial voltage state when the voltage state signal indicates that there is voltage.

[0048] Furthermore, the venting module includes: An NMOS transistor is used to receive voltage status signals by connecting its gate to the output of a voltage monitoring module and grounding its source. The discharge resistor is used to connect the drain of the NMOS transistor with its first end and the ungrounded terminal of the energy storage element with its second end. When the voltage status signal indicates that there is voltage, the NMOS transistor is turned on, allowing the energy storage element to release energy through the discharge resistor.

[0049] Furthermore, it also includes a reference ground providing module, which includes a pull-down resistor for connecting its first terminal to the output of the voltage monitoring module and its second terminal to ground, providing a zero-voltage reference to the output of the voltage monitoring module when the turbine generator is de-energized.

[0050] Furthermore, the voltage monitoring module, switching control module, delay module, and power-off execution module are all composed of discrete analog components, and the device does not require continuous power supply to the control circuit after the turbine generator is powered off.

[0051] Furthermore, the power-off delay time corresponding to the preset threshold is jointly set by the capacitance value of the energy storage element and the resistance value of the charging resistor in the delay module.

[0052] The system provided in this embodiment for automatic switching and delayed power cut-off of downhole power during logging-while-drilling has all the advantages of the method for automatic switching and delayed power cut-off of downhole power during logging-while-drilling provided in Embodiment 1.

[0053] Example 3 This embodiment also discloses a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in Embodiment 1.

[0054] Example 4 This embodiment also discloses a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0055] Example 5 This embodiment also discloses a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0056] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for automatic switching and delayed power cut-off of downhole power during logging-while-drilling, characterized in that, include: Detect the power supply status of the turbine generator and obtain the status judgment result; When the state determination result indicates a power supply state, the turbine generator is controlled to supply power to the load, and the energy storage element is allowed to release energy. When the state determination result indicates a power outage, control the power supply from the battery to the load and start timing based on the charging process of the energy storage element; When the timer reaches a preset threshold, a power-off trigger signal is received, cutting off the battery's power supply to the load.

2. The method according to claim 1, characterized in that, The process of detecting the power supply status of the turbine generator and obtaining the status judgment result includes: The gate-source voltage of the PMOS transistor automatically responds to the voltage changes of the turbine generator to distinguish between the power supply state and the power outage state.

3. The method according to claim 1, characterized in that, The process of releasing energy from energy storage devices includes: When the turbine generator is in the power supply state, the NMOS transistor is turned on, so that the energy storage element releases the stored energy through the discharge resistor.

4. The method according to claim 1, characterized in that, The process of controlling the supply of power from the battery to the load and initiating timing based on the charging process of the energy storage element includes: When the turbine generator is in the power-off state, the first PMOS transistor is turned on to connect the battery to the load, and the second PMOS transistor is turned on to enable the energy storage element to start charging through the charging resistor, thereby starting the timing.

5. The method according to claim 1, characterized in that, When the timer reaches a preset threshold and a power-off trigger signal is received, the process of cutting off the battery's power supply to the load includes: When the voltage of the energy storage element during the charging process reaches a level that causes the gate-source voltage of the third PMOS transistor to fall below the turn-on threshold, the third PMOS transistor automatically turns off, thereby cutting off the power supply from the battery to the load.

6. The method according to claim 5, characterized in that, The gate of the third PMOS transistor is connected to the common node of the energy storage element and the charging resistor, and the voltage of the energy storage element serves as the control signal for the third PMOS transistor.

7. The method according to claim 1, characterized in that, The method further includes: providing a zero-voltage reference for the gate of the relevant PMOS transistor when the turbine generator is in the power-off state by setting a pull-down resistor, so as to ensure that the relevant PMOS transistor is turned on normally.

8. The method according to claim 1, characterized in that, The method is executed by a circuit consisting of discrete analog components only, and does not require continuous power supply to the control circuit after the turbine generator is powered off. The discrete analog components include diodes, resistors, capacitors, and MOSFETs, and the temperature rating of the discrete analog components is at least 175°C.

9. The method according to claim 1, characterized in that, The power outage delay time corresponding to the preset threshold is set by adjusting the capacitance value of the energy storage element or the resistance value of the charging resistor.

10. A system for automatic switching and delayed power cut-off of downhole power during logging-while-drilling, characterized in that, include: The voltage monitoring module is used to monitor the output voltage of the turbine generator and obtain voltage status signals; The switching control module is used to couple the turbine generator to the load when the voltage status signal indicates that there is voltage, and to couple the battery to the load when the voltage status signal indicates that there is no voltage, so as to obtain the power supply switching result; The delay module is used to charge the energy storage element when the power supply switching result is battery power, so as to obtain a gradually rising charging voltage signal. The power-off execution module is used to disconnect the connection between the battery and the load when the charging voltage signal reaches a preset threshold, thereby obtaining a power-off state.

Images