Nuclear magnetic resonance emitter protection module
A nuclear magnetic resonance and protection module technology, which is applied in the direction of electronic magnetic resonance/nuclear magnetic resonance detection, emergency protection circuit device, and protection against overcurrent, which can solve the problem of reduced maximum allowable operating current, high channel temperature, and inability Protect high-power switching tubes and other issues to avoid damage due to thermal breakdown
Pending Publication Date: 2020-08-21
CHINA PETROCHEMICAL CORP +4
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Problems solved by technology
When working in salt water slurry, the mud resistivity is extremely low, and the load increases. At this time, sufficient B1 magnetic field strength must be maintained, and the emission current increases greatly, resulting in increased heat loss of high-power switching tubes, making the channel temperature too high. Cause thermal breakdown and damage; sometimes, due to the high ambient temperature of the wellbore, the power dissipation of the high-power switch tube decreases with the increase of the ambient temperature, that is to say, the maximum allowable operating current also decreases, and the junction of the high-power switch tube The temperature rises sharply, and once it approaches or exceeds the maximum allowable junction temperature, it can cause thermal breakdown damage
[0005] Because the dissipation power of the high-power switching tube decreases with the increase of the ambient temperature, the maximum allowable operating current decreases with the increase of the temperature, and the threshold of the overcurrent protection circuit in the current nuclear magnetic resonance instrument is fixed. Can not protect high power switching tube
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[0030] Such as figure 1 As shown, a nuclear magnetic resonance transmitter protection module is mainly composed of a current sampling unit 1, a temperature probe 2, a signal processing unit 3, and a logic operation unit 4.
[0031] The current sampling unit 1 performs current sampling on the high-power transmitting circuit.
[0032] The temperature probe 2 is a temperature sensor, which can convert a temperature signal into a voltage signal.
[0033] The signal processing unit 3 includes a temperature probe, an auxiliary circuit provided by a current sampling circuit, a filtering and conditioning circuit, and a time delay circuit. What is especially important in this module is the design of the overcurrent protection reference threshold circuit. The overcurrent reference threshold can change with the ambient temperature, and dynamically track the maximum allowable operating current of the high-power switch tube of the transmitter under the current temperature condition in rea...
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The invention relates to the technical field of nuclear magnetic resonance logging, and provides a nuclear magnetic resonance emitter protection module, which comprises an overcurrent protection unit,an overheating protection unit and a protection state delay release unit, has overheating and overcurrent protection functions, and avoids thermal breakdown damage of a high-power switch tube of a nuclear magnetic emitter. According to the invention, the maximum allowable current of the high-power switch tube can be dynamically tracked in real time, the overcurrent protection threshold can be adjusted in real time according to the tracking result, the overcurrent, overheating and protection state delay release functions are achieved at the same time, and the reliability of the high-power switch tube is further improved.
Description
technical field [0001] The invention relates to the technical field of nuclear magnetic resonance logging, and provides a nuclear magnetic resonance transmitter protection module. Background technique [0002] NMR logging technology is currently the only logging method that can directly measure the properties of formation fluids, and has obvious advantages. NMR can use the principle of NMR to detect the formation information around the wellbore, and can identify and evaluate the formation fluid quantitatively and qualitatively. [0003] In the process of well logging, nuclear magnetic resonance needs to emit radio frequency electromagnetic field through a high-power transmitting circuit, so that H protons with the same Larmor frequency can resonate, so as to realize the detection of fluid properties. [0004] The current high-power transmitting circuit is a full-wave power amplifier in switch mode, which is composed of a high-power switch tube as the core. The transmitting...
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IPC IPC(8): H02H3/08H02H5/04H02H3/06E21B47/00E21B49/00G01V3/32
CPCE21B47/00E21B49/00G01V3/32H02H3/066H02H3/08H02H5/04
Inventor 葛承河郭红旗刘磊刘春莹于云华闫永平
Owner CHINA PETROCHEMICAL CORP