阅读说明：本技术 一种井间电磁发射天线自适应无级变容谐振系统及其工作方法 (Self-adaptive stepless variable-capacitance resonance system of electromagnetic transmitting antenna between wells and working method of self-adaptive stepless variable-capacitance resonance system ) 是由 党峰 陈涛 王炜 刘彤 程刚 于 2019-08-16 设计创作，主要内容包括：本发明提供一种井间电磁发射天线自适应无级变容谐振系统及其工作方法,包括发射天线、电流传感器、数模转换器、采集控制处理器和谐振电容；采集控制处理器产生继电器控制信号,控制切换电容,发射天线中传输的电流经电流传感器转化为成比例的磁场电压,磁场电压通过数模转换器转换为模拟电压信号并传输给采集控制处理器,采集控制处理器找到模拟电压最大值,然后采集控制处理器产生继电器控制信号,控制与模拟电压最大值对应的电容导通。本发明解决了发射天线由于频率增大而导致的发射电流太小,以至于发射磁矩在地层中所产生的二次长信号不容易被井间电磁接收系统所测量的问题,有效提高了井间电磁成像测井系统的测量精度与井间距离。(The invention provides an inter-well electromagnetic transmitting antenna self-adaptive stepless variable capacitance resonance system and a working method thereof, wherein the inter-well electromagnetic transmitting antenna self-adaptive stepless variable capacitance resonance system comprises a transmitting antenna, a current sensor, a digital-to-analog converter, an acquisition control processor and a resonance capacitor; the acquisition control processor generates a relay control signal to control the switching of the capacitor, the current transmitted in the transmitting antenna is converted into proportional magnetic field voltage through the current sensor, the magnetic field voltage is converted into an analog voltage signal through the digital-to-analog converter and transmitted to the acquisition control processor, the acquisition control processor finds the maximum value of the analog voltage, then the acquisition control processor generates the relay control signal, and the capacitor corresponding to the maximum value of the analog voltage is controlled to be switched on. The invention solves the problem that the transmitting antenna has too small transmitting current due to the increase of frequency, so that a secondary long signal generated by a transmitting magnetic moment in a stratum is not easy to be measured by an interwell electromagnetic receiving system, and effectively improves the measurement precision and the interwell distance of the interwell electromagnetic imaging logging system.)

1. An interwell electromagnetic transmitting antenna self-adaptive stepless variable capacitance resonance system is characterized by comprising a transmitting antenna, a current sensor, a digital-to-analog converter, an acquisition control processor and a resonance capacitor;

the current sensor is used for sensing the current transmitted by the transmitting antenna, converting the current into magnetic field voltage and outputting the magnetic field voltage to the digital-to-analog converter;

the digital-to-analog converter is used for converting the received magnetic field voltage into analog quantity voltage and outputting the analog quantity voltage to the acquisition control processor;

the acquisition control processor is used for generating a relay control signal to the resonant capacitor, controlling the on-off of the capacitors in different branches, receiving the analog quantity voltage when the capacitors in each branch are respectively conducted, searching the maximum value of the analog quantity voltage, and conducting the capacitor corresponding to the maximum value of the analog quantity voltage;

the resonant capacitor comprises a plurality of parallel branches, a relay and a capacitor are connected in series on each branch, the signal input end of the relay is connected with the signal output end of the acquisition control processor, and the resonant capacitor is connected with the transmitting antenna in series; and the relay controls the on-off of the capacitor in each branch circuit according to the received relay control signal.

2. The adaptive stepless variable capacitance resonance system of the electromagnetic transmitting antenna between wells as claimed in claim 1, wherein the current sensor is a surface-mounted current sensor.

3. The adaptive stepless variable capacitance resonance system of the electromagnetic transmitting antenna between wells as claimed in claim 1, wherein the relays comprise relay drivers and electromagnetic relays, and signal input ends of the relay drivers are connected with signal output ends of the acquisition control processors.

4. The adaptive stepless variable capacitance resonance system of the electromagnetic transmitting antenna between wells as claimed in claim 1, wherein the capacitors are all noninductive capacitors.

5. The adaptive stepless variable capacitance resonance system of the interwell electromagnetic transmitting antenna according to claim 1, characterized in that the capacitors are all capacitor packs.

6. The method of any one of claims 1-5, wherein the acquisition control processor generates a relay control signal to control the switched capacitor, the current transmitted in the transmitting antenna is converted to a proportional magnetic field voltage by the current sensor, the magnetic field voltage is converted to an analog voltage signal by the digital-to-analog converter and transmitted to the acquisition control processor, the acquisition control processor finds the maximum value of the analog voltage, and the acquisition control processor generates the relay control signal to control the conduction of the capacitor corresponding to the maximum value of the analog voltage.

7. The working method of the adaptive stepless variable-capacitance resonant system of the interwell electromagnetic transmitting antenna according to any one of claim 6, is characterized by comprising the following steps:

step 1, sequencing a plurality of branches in a resonant capacitor from small to large according to the capacitance; the acquisition control processor generates a relay control signal to enable a capacitor on the ith branch to be conducted, i is a natural number, current transmitted in the transmitting antenna is converted into proportional magnetic field voltage through the current sensor, and the magnetic field voltage is converted into an analog voltage signal through the digital-to-analog converter and transmitted to the acquisition control processor;

step 2, the acquisition control processor generates a relay control signal to cut off the capacitor on the ith branch and switch on the capacitor on the (i + 1) th branch; the current transmitted in the transmitting antenna is converted into proportional magnetic field voltage through the current sensor, and the magnetic field voltage is converted into an analog voltage signal through the digital-to-analog converter and transmitted to the acquisition control processor;

and 3, if the analog voltage when the capacitor on the ith +1 branch is conducted is larger than the analog voltage when the capacitor on the ith branch is conducted, updating i to be i +1 and repeating the step 2, otherwise, generating a relay control signal by the acquisition control processor to conduct the capacitor on the ith branch.

Technical Field

The invention relates to an oil-gas exploration technology, in particular to an inter-well electromagnetic transmitting antenna self-adaptive stepless variable capacitance resonance system and a working method thereof.

Background

With the development of exploration technology, determining the connectivity of stratum sand bodies, searching for missed oil layers, monitoring macroscopic displacement effects, designing encrypted wells and improving the simulation precision of oil reservoirs become key work in the middle and later stages of oil field development, but because the radial detection range of the traditional logging method is small, the construction process is complicated, the requirements can not be well met, and a novel logging instrument, namely an interwell electromagnetic logging instrument, must be designed. The measurement of resistivity distribution between shafts by an interwell electromagnetic logging instrument is an important frontier for the development of the current geophysical application technology. As shown in FIG. 1, the downhole portion of the interwell electromagnetic tool is primarily comprised of a transmitter and a receiver, and during measurement, a low frequency transmitter is placed in the transmitter well, and the vertical and horizontal components of the magnetic field are measured in one or more adjacent receiver wells, to directly measure the electrical properties of the interwell formations with high accuracy and resolution.

However, since the transmission frequency band is wide, when the frequency is high, the transmission current is very small, so that the secondary long signal generated by the transmission magnetic moment in the formation is not easily measured by the inter-well electromagnetic receiving system, and the measurement accuracy and the inter-well distance are reduced.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides an inter-well electromagnetic transmitting antenna self-adaptive stepless variable capacitance resonance system and a working method thereof, solves the problem that the transmitting current of the transmitting antenna is too small due to the increase of the frequency, so that a secondary long signal generated by a transmitting magnetic moment in a stratum is not easily measured by an inter-well electromagnetic receiving system, and effectively improves the measurement precision and the inter-well distance of an inter-well electromagnetic imaging logging system.

The invention is realized by the following technical scheme:

an inter-well electromagnetic transmitting antenna self-adaptive stepless variable capacitance resonance system comprises a transmitting antenna, a current sensor, a digital-to-analog converter, an acquisition control processor and a resonance capacitor;

the current sensor is used for sensing the current transmitted by the transmitting antenna, converting the current into magnetic field voltage and outputting the magnetic field voltage to the digital-to-analog converter;

the digital-to-analog converter is used for converting the received magnetic field voltage into analog quantity voltage and outputting the analog quantity voltage to the acquisition control processor;

the acquisition control processor is used for generating a relay control signal to the resonant capacitor, controlling the on-off of the capacitors in different branches, receiving the analog quantity voltage when the capacitors in each branch are respectively conducted, searching the maximum value of the analog quantity voltage, and conducting the capacitor corresponding to the maximum value of the analog quantity voltage;

the resonant capacitor comprises a plurality of parallel branches, a relay and a capacitor are connected in series on each branch, the signal input end of the relay is connected with the signal output end of the acquisition control processor, and the resonant capacitor is connected with the transmitting antenna in series; and the relay controls the on-off of the capacitor in each branch circuit according to the received relay control signal.

Preferably, the current sensor is a surface-mounted current sensor.

Preferably, the relays all include relay drive and electromagnetic relay, and the signal input part of relay drive is connected with the signal output part of collection control treater.

Preferably, the capacitors are all noninductive capacitors.

Preferably, the capacitors are all capacitor packages.

According to the working method of the inter-well electromagnetic transmitting antenna self-adaptive stepless variable capacitance resonance system, the acquisition control processor generates a relay control signal to control switching of the capacitance, current transmitted in the transmitting antenna is converted into proportional magnetic field voltage through the current sensor, the magnetic field voltage is converted into an analog voltage signal through the digital-to-analog converter and transmitted to the acquisition control processor, the acquisition control processor finds the maximum value of the analog voltage, then the acquisition control processor generates the relay control signal, and the capacitance corresponding to the maximum value of the analog voltage is controlled to be switched on.

Preferably, the method specifically comprises the following steps:

step 1, sequencing a plurality of branches in a resonant capacitor from small to large according to the capacitance; the acquisition control processor generates a relay control signal to enable a capacitor on the ith branch to be conducted, i is a natural number, current transmitted in the transmitting antenna is converted into proportional magnetic field voltage through the current sensor, and the magnetic field voltage is converted into an analog voltage signal through the digital-to-analog converter and transmitted to the acquisition control processor;

step 2, the acquisition control processor generates a relay control signal to cut off the capacitor on the ith branch and switch on the capacitor on the (i + 1) th branch; the current transmitted in the transmitting antenna is converted into proportional magnetic field voltage through the current sensor, and the magnetic field voltage is converted into an analog voltage signal through the digital-to-analog converter and transmitted to the acquisition control processor;

and 3, if the analog voltage when the capacitor on the ith +1 branch is conducted is larger than the analog voltage when the capacitor on the ith branch is conducted, updating i to be i +1 and repeating the step 2, otherwise, generating a relay control signal by the acquisition control processor to conduct the capacitor on the ith branch.

Compared with the prior art, the invention has the following beneficial technical effects:

when the resonant system is used, all branches in the resonant capacitor are respectively conducted, the current information (corresponding to analog quantity voltage) corresponding to the condition that all branch capacitors are respectively conducted is acquired through the current sensor and the digital-to-analog converter, then the maximum current value is found, namely the optimal resonant matching capacitor is found, and the branch where the optimal matching capacitor is located is conducted, so that the matching degree of the resonant capacitor is improved, the transmitting antenna can still keep higher transmitting current when the frequency is increased, and the frequency width of the transmitting current can be widened. The invention solves the problem that the transmitting antenna has too small transmitting current due to the increase of frequency, so that the secondary signal generated by the transmitting magnetic moment in the stratum is not easy to be measured by an interwell electromagnetic receiving system, effectively improves the measuring precision and interwell distance of the interwell electromagnetic imaging logging system, and provides powerful support for the subsequent instrument production logging. The reliability and realizability of the invention are verified in the experimental process.

Furthermore, the surface-mounted current sensor is packaged by a small flat surface mounting seat SOIC8, a high-level side differential amplifier or other expensive isolation technologies are not needed, the design requirement of narrow underground space of the petroleum logging can be met, and the problems of testing precision and high common-mode input voltage range limitation caused by instability of a reference base of a load in a common current detection point insertion monitoring resistance method are effectively avoided.

Furthermore, the non-inductive capacitor is used as an adaptive stepless variable capacitance unit device of the electromagnetic transmitting antenna between wells, so that the inductance change of the electromagnetic transmitting antenna between wells caused in the switching process of the capacitor array is overcome, and the stability of the electromagnetic logging system between wells is ensured.

According to the method, each branch in the resonant capacitor is conducted respectively, corresponding current information is acquired when each branch is conducted respectively, then the optimal resonant matching capacitor is found, the branch where the optimal matching capacitor is located is conducted, the matching degree of the resonant capacitor is improved, the transmitting antenna can still keep higher transmitting current when the frequency is increased, the problem that the transmitting current of the transmitting antenna is too small due to the increase of the frequency, so that secondary signals generated by the transmitting magnetic moment in a stratum are not easily measured by an interwell electromagnetic receiving system is solved, and the measuring accuracy and the interwell distance of the interwell electromagnetic imaging logging system are effectively improved.

Drawings

FIG. 1 is a schematic diagram of an interwell electromagnetic logging operation;

FIG. 2 is a schematic diagram of the transmitter composition of the electromagnetic logging tool between wells;

FIG. 3 is a schematic diagram of an inter-well electromagnetic tool transmit antenna resonant capacitor assembly;

fig. 4 is a schematic diagram of the capacitive equivalence.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

As shown in fig. 2, the adaptive stepless variable capacitance resonance system of the electromagnetic transmitting antenna between wells of the invention comprises the transmitting antenna, a current sensor, a digital-to-analog converter, an acquisition control processor and a resonance capacitor.

And the current sensor is used for sensing the current transmitted by the transmitting antenna, converting the current into magnetic field voltage and outputting the magnetic field voltage to the digital-to-analog converter.

And the digital-to-analog converter is used for converting the received magnetic field voltage into analog quantity voltage and outputting the analog quantity voltage to the acquisition control processor.

And the acquisition control processor is used for generating a relay control signal to the resonant capacitor, controlling the on-off of the capacitors in different branches, receiving the analog quantity voltage when the capacitors in the branches are respectively switched on, searching the maximum value of the analog quantity voltage, and switching on the capacitor corresponding to the maximum value of the analog quantity voltage. The method specifically comprises the steps of finding the maximum value of the analog quantity voltage by utilizing a successive approximation method, namely continuously collecting the current of the transmitting antenna at the current sensor, continuously comparing the current with the current value collected at the previous time, if the current value is larger than the current value at the previous time, indicating that the underground transmitting part does not resonate, continuously adjusting the resonant capacitor array according to a certain step until the current value collected by the current sensor is smaller than the current value at the previous time, indicating that the current reaches the maximum value, and then the time is the required actual resonant capacitor, and considering that the transmitting part is completely in a resonant state at the time, namely the state required by the invention, so that the maximum output current of the transmitting antenna is reached.

As shown in fig. 3, the resonant capacitor includes a plurality of parallel branches, each branch is connected in series with a relay and a capacitor, a signal input terminal of the relay is connected with a signal output terminal of the acquisition control processor, and the resonant capacitor is connected in series with the transmitting antenna. The relay controls the on-off of each branch circuit according to the received relay control signal, so that the capacitance channel is switched, and the switching of different capacitance values is realized.

The current sensor adopts a surface-mounted precise current sensor which is packaged by adopting a small flat surface mounting seat SOIC8, and the sensor does not need to use a high-level side differential amplifier or other expensive isolation technologies and can realize the narrow design requirement of the underground space of the petroleum logging.

The acquisition control processor adopts a DSP + FPGA + DDS architecture. And completing communication between the underground and the ground system, synchronizing the clocks of the transmitting well and the receiving well and generating control signals of other modules according to a certain time sequence.

The DSP is responsible for receiving a ground instruction and uploading data such as coil current and downhole temperature acquired downhole, the FPGA generates corresponding control time sequences according to the received instruction, and all the control time sequences are control logics when a circuit is designed, for example, the conduction of a switch is controlled to realize the conduction of a resonant capacitor, a logic control signal for controlling the DDS is generated, different transmitting frequencies are generated, and the like.

The relays comprise relay drivers and electromagnetic relays, and signal input ends of the relay drivers are connected with signal output ends of the acquisition control processors.

The capacitors are all noninductive capacitors, so that the inductance change of the electromagnetic transmitting antenna among wells is avoided in the capacitance switching process. The capacitors are preferably capacitor packages, as shown in fig. 4.

The working process of the self-adaptive stepless variable capacitance resonance system of the electromagnetic transmitting antenna between wells is as follows: the acquisition control processor generates a relay control signal to control the switching of the capacitor, current transmitted in the transmitting antenna is converted into proportional magnetic field voltage through the current sensor, the magnetic field voltage is converted into an analog voltage signal through the digital-to-analog converter and transmitted to the acquisition control processor, the acquisition control processor finds the maximum value of the analog voltage through a successive approximation method by using the digital processor, then the acquisition control processor generates the relay control signal, and the capacitor corresponding to the maximum value of the analog voltage is controlled to be switched on. Namely, the maximum voltage value of the current sensor is judged by real-time monitoring, and the place with the maximum voltage (namely the place with the maximum current of the transmitting antenna) is the optimal design point of the resonant capacitance of the transmitting antenna.