Induced polarization logging instrument system based on plasma optical fiber sensor and acquisition method

Abstract

The application discloses a kind of induction logging instrument systems and acquisition method based on plasma optical fiber sensor, including ground current emission source and at least one well in current emission source and well in receiving acquisition device, the well in receiving acquisition device is connected with the optical system of induction signal detection being arranged on ground, the optical system is composed of sequentially connected broadband light source, polarizer, polarization controller, fiber optic circulator and spectrum analyzer, the fiber optic circulator is connected with well in receiving acquisition device and spectrum analyzer respectively, at least two plasma resonance optical fiber sensing probes are arranged in the well in receiving acquisition device. There is no mutual interference or crosstalk between plasma resonance optical fiber sensor, optical fiber sensor and emission power supply and antenna, and it is not easy to be disturbed by environmental electromagnetic noise, and multi-channel large data high-speed real-time transmission can be realized by using armored photoelectric composite cable connected with each well in receiving acquisition device.

Description

Technical Field

[0001] This invention relates to the fields of geophysical exploration technology and surface induced polarization exploration technology, specifically to an induced polarization logging instrument system and acquisition method based on a plasma fiber optic sensor. Background Technology

[0002] Geophysical exploration methods mainly include seismic methods, direct current methods, magnetic methods, gravity methods, electromagnetic methods, and radiometric methods.

[0003] Currently, frequency-domain or time-domain electromagnetic data acquisition systems used in the industry typically include induction coil or fluxgate type single-component or three-component magnetic field sensors, one or two pairs of orthogonal non-polarized electrode pairs as electric field sensors, and modules for signal amplification, filtering and noise reduction, analog-to-digital conversion, long-distance transmission, or local storage. These traditional electromagnetic data acquisition systems suffer from high power consumption, high instrument noise floor, weak electromagnetic interference resistance, bulky electromagnetic sensors, high instrument costs, low production efficiency, and difficulty in large-scale mass production. Furthermore, due to the weak electromagnetic interference resistance of electronic instruments and sensors, qualified electromagnetic field data are often unacceptable in environments with strong electromagnetic interference. Summary of the Invention

[0004] The purpose of this invention is to provide an induced polarization logging instrument system and acquisition method based on a plasma fiber optic sensor to solve existing problems.

[0005] The induced polarization (IP) logging instrument system based on plasma fiber optic sensors includes a surface current emission source, a borehole current emission source, and at least one borehole receiving and acquisition device. The borehole receiving and acquisition device is connected to an optical system for detecting IPI signals located on the surface. The optical system consists of a broadband light source, a polarizer, a polarization controller, a fiber optic circulator, and a spectrometer connected in sequence. The fiber optic circulator is connected to both the borehole receiving and acquisition device and the spectrometer. The borehole receiving and acquisition device contains at least two plasma resonance fiber optic sensing probes, wherein:

[0006] The plasma resonance fiber optic sensing probe is used to collect induced polarization signals in the well and transmits them through an armored optoelectronic composite cable to a fiber laser signal modulation and demodulation instrument for demodulation to obtain induced polarization data in the well.

[0007] Furthermore, it also includes an instrument vehicle on the ground, and the receiving and acquisition device in the well is connected to the instrument vehicle via an armored optical-electric composite cable.

[0008] Furthermore, there are multiple receiving and acquisition devices in the well, and the distance between any two adjacent receiving and acquisition devices in the well is 5-10m.

[0009] Furthermore, the two plasma resonance fiber optic sensing probes in the well-receiving and acquisition device form a pair of well-induced polarization signal measurement probes, or every two adjacent well-receiving and acquisition devices are connected by armored optoelectronic composite cables to form a pair of well-induced polarization signal measurement probes, used to measure the potential signal difference of the primary or secondary field in the well between each pair of polarization signal measurement probes.

[0010] Furthermore, the ground current transmitting source is connected to the ground transmitting antenna via a ground control device;

[0011] The in-well current transmitting source is installed in the in-well receiving and acquisition device, and is connected to the in-well transmitting antenna through an in-well control device installed in the in-well receiving and acquisition device.

[0012] The plasma resonance fiber optic sensing probe is used to measure the induced polarization signal in the well during excitation current emission.

[0013] Furthermore, the ground transmitting antenna consists of four long grounded wires surrounding the well, with grounding electrodes at both ends of the long grounded wires. The ground current transmitting source is used to alternately supply power to the long grounded wires deployed in different directions.

[0014] Furthermore, the ground transmitting antenna is a square large loop transmitting coil or a circular large loop transmitting coil surrounding the well.

[0015] Furthermore, the transmitting antenna in the well consists of ring-shaped non-polarized transmitting electrodes installed at the upper and lower parts of the receiving and acquisition device in the well, respectively, and the current transmitting source in the well is used to alternately supply power to the two ring-shaped non-polarized transmitting electrodes.

[0016] Furthermore, the transmitting antenna in the well is a three-component square transmitting coil or a three-component circular transmitting coil installed in the upper part of the receiving and acquisition device in the well.

[0017] A data acquisition method for an induced polarization logging instrument based on a plasma fiber optic sensor includes the following steps:

[0018] S1. Obtain ground-well induced polarization data. The ground-well induced polarization data is obtained by modulating and demodulating the ground-well induced polarization signals collected by the plasma resonance fiber optic sensing probe at each measuring point using a fiber laser signal modulator and demodulator. The induced polarization signal is the ground-well induced polarization signal collected point by point by the receiving and acquisition device in the well after the ground current emission source continuously emits a high-power excitation current into the ground. The receiving and acquisition device in the well moves from the bottom of the well to the wellhead and collects the signal at a preset distance. The ground-well induced polarization data includes ground-well time-domain induced polarization data and ground-well frequency-domain induced polarization data.

[0019] S2. Obtain well-induced polarization data. The well-induced polarization data is obtained by modulating and demodulating the well-induced polarization signals collected by the plasma resonance fiber optic sensing probe at each measuring point using a fiber laser signal modulator and demodulator. The well-induced polarization signal is the well-induced polarization signal collected point by point by the well-receiving and acquisition device after the well current emission source continuously and alternately emits excitation current into the well. The well-receiving and acquisition device moves from the bottom of the well to the wellhead and collects the well-induced polarization signal at a preset distance. The well-induced polarization data includes well-time domain induced polarization data and well-frequency domain induced polarization data.

[0020] The ground-well time-domain induced polarization data or the well time-domain induced polarization data are used by the host computer to perform time-domain and frequency-domain inversion imaging to obtain three-dimensional induced polarization data. The three-dimensional induced polarization data is used to indicate the distribution pattern of the time-domain complex resistivity of the underground strata around the well in three-dimensional space, or the distribution pattern of the frequency-domain complex resistivity of the underground strata around the well in three-dimensional space.

[0021] And by inverting the relationship between the time-domain complex resistivity and the frequency-domain complex resistivity, the distribution pattern of formation polarizability in three-dimensional space can be obtained;

[0022] Based on the distribution patterns of the time-domain complex resistivity, frequency-domain complex resistivity, and polarizability of the underground strata in three-dimensional space, the geoelectric characteristics and induced polarization characteristics of the underground strata or rock units are determined.

[0023] The beneficial effects of this invention are as follows: The induced polarization logging instrument system and acquisition method based on plasma fiber optic sensors provided by this invention can quickly and cost-effectively detect the distribution patterns of formation complex resistivity and formation polarizability in the three-dimensional underground working area around the well, as well as their relationship with underground oil and gas or mineral resources. It can also improve the ability to distinguish target geological bodies, greatly reduce the interference of various human noises on existing electronic induced polarization logging instruments, improve the signal-to-noise ratio of induced polarization data in the well, indicate the anisotropic characteristics of formation resistivity, provide information such as formation occurrence, and realize the comprehensive interpretation and evaluation of reservoir parameters. Because of the use of plasma resonance fiber optic sensors, the induced polarization data acquisition device in the well no longer has any electronic receiving sensors or induction coil or fluxgate magnetic field sensors as receiving sensors for induced polarization signals. There is no mutual interference or crosstalk between plasma resonance fiber optic sensors, or between plasma resonance fiber optic sensors and the instrument's transmitting power supply and antenna. The plasma resonance fiber optic sensors and the fiber optic modulation and demodulation instruments in the ground instrument vehicle are also less susceptible to electromagnetic noise interference from the surrounding environment of the three-dimensional work area. Furthermore, the armored optoelectronic composite cable connecting the receiving and acquisition devices in each plasma resonance well can be used to achieve high-speed real-time transmission of multi-channel, multi-parameter big data, thus overcoming most of the shortcomings of conventional electronic induced polarization logging instruments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the optical system structure for detecting induced polarization signals in a well based on a plasma fiber optic sensor, according to the present invention.

[0025] Figure 2 This is a schematic diagram of an induced polarization logging instrument system and a ground long wire transmitting structure for an induced polarization fiber optic sensor, which is one embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the induced polarization logging instrument system of the plasma fiber optic sensor and the surface square large loop transmitting coil structure, which is a second embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the induced polarization logging instrument system and the circular large loop transmitting coil structure of the plasma fiber optic sensor according to the third embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of the structure of the induced polarization logging instrument electrical source excitation and acquisition system based on a plasma fiber optic sensor according to the present invention;

[0029] Figure 6 This is a schematic diagram of the structure of the electro-source excitation array acquisition system for the induced polarization logging instrument based on a plasma fiber optic sensor according to the present invention;

[0030] Figure 7 This is a schematic diagram of the structure of the magnetic source-excited square coil acquisition system of the induced polarization logging instrument based on a plasma fiber optic sensor according to the present invention;

[0031] Figure 8 This is a schematic diagram of the structure of the magnetic source-excited square coil array acquisition system of the induced polarization logging instrument based on plasma fiber optic sensor of the present invention;

[0032] Figure 9 This is a schematic diagram of the structure of the magnetic source-excited circular coil acquisition system of the induced polarization logging instrument based on a plasma fiber optic sensor according to the present invention;

[0033] Figure 10 This is a schematic diagram of the structure of the magnetic source-excited circular coil array acquisition system of the induced polarization logging instrument based on plasma fiber optic sensor of the present invention.

[0034] Reference numerals: Surface current transmitter-1, Borehole current transmitter-2, Surface transmitting antenna-4, Excitation current-5, Instrument vehicle-6, Borehole receiving and acquisition device-7, Broadband light source-72, Polarizer-73, Polarization controller-74, Fiber optic circulator-75, Plasma resonance fiber optic sensing probe-76, Spectrometer-77, Armored optoelectronic composite cable-28, Surface control device-30, Borehole control device-31, Grounding electrode-41, Long conductor-42, Square large loop transmitting coil-43, Circular large loop transmitting coil-44, Circular non-polarized transmitting electrode-46, Three-component square transmitting coil-47, Three-component circular ring transmitting coil-48, Fiber laser signal modulator-demodulator-8. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0037] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0038] Furthermore, for clarity and brevity, descriptions of well-known structures, functions, and configurations may have been omitted. Those skilled in the art will recognize that various changes and modifications can be made to the examples described herein without departing from the spirit and scope of this disclosure.

[0039] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0040] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0041] The present invention relates to an induced polarization logging instrument system based on a plasma fiber optic sensor, comprising a high-power pulse (time domain) or sine wave or cosine wave (frequency domain) current transmitter 1 on the ground, a pulse (time domain) or sine wave or cosine wave (frequency domain) current transmitter 2 in the well, and a receiving and acquisition device 7 in the well.

[0042] The ground-based high-power time-domain (pulse) or frequency-domain (sine wave or cosine wave) current transmitter is connected to the ground transmitting antenna 4 via the ground control device 30 of the high-power pulse or sine wave or cosine wave current transmitter 1. The ground control device 30 of the high-power pulse or sine wave or cosine wave current transmitter 1 provides a high-power square wave pulse excitation current or a sine wave or cosine wave excitation current 5 to the transmitting antenna 4.

[0043] The time-domain (pulse) or frequency-domain (sine wave or cosine wave) current transmitter 2 in the well is connected to the transmitting antenna in the well through the control device 31 in the well. The control device 31 in the well provides the transmitting antenna with a square wave pulse excitation current or a sine wave or cosine wave excitation current 5.

[0044] The plasma resonance fiber optic sensing probe 76 of the well receiving and acquisition device 7 moves slowly from the bottom of the well to the wellhead during the transmission of the excitation current 5, and performs fixed-point measurements according to the pre-designed measurement point spacing. It can also perform continuous measurements during the slow movement.

[0045] The time-domain (pulse) or frequency-domain (sine wave or cosine wave) current transmitter 2, the control device 31, and the transmitting antenna in the well are installed inside the cavity of the receiving and acquisition device 7 in the well.

[0046] The ground transmitting antenna 4 is a long grounding conductor 42 with grounding electrodes 41 at both ends surrounding the well, or a square large loop transmitting coil 43 or a circular large loop transmitting coil 44 surrounding the well.

[0047] The transmitting antenna in the well is a ring-shaped non-polarized transmitting electrode 46 with two excitation currents 5 at both ends installed in the fiber optic induced polarization signal receiving and acquisition device 7 in the well, or a three-component square transmitting coil 47 or a three-component ring transmitting coil 48 installed at one end in the fiber optic induced polarization signal receiving and acquisition device 7.

[0048] Figure 1This is a schematic diagram of the optical system structure for induced polarization signal detection based on a plasma fiber optic sensor according to the present invention. The in-well receiving and acquisition device 7 is connected to the optical system 71 for induced polarization signal detection installed on the ground. The optical system 71 consists of a broadband light source 72 with a bandwidth of 1250-1650nm, a polarizer 73, a polarization controller 74, a fiber optic circulator 75, a plasma resonance fiber optic sensing probe 76, the in-well receiving and acquisition device 7, and a spectrometer 77.

[0049] The plasma resonance fiber optic sensing probe 76 is a miniature and chemically inert sensor that can be inserted into the measurement medium to perform in-situ and continuous monitoring of electrochemical reactions and interfacial dynamics changes near the sensor surface. By detecting the disturbance of surface plasma waves propagating on its surface, the sensor can measure and monitor its electrochemical dynamics characteristics without interfering with its normal operation.

[0050] The receiving and acquisition device 7 in the well contains two plasma resonance fiber optic sensing probes 76 forming a pair of measuring probes, with the distance between the two plasma resonance fiber optic sensing probes 76 being between 1 and 5 meters.

[0051] The multiple in-well receiving and acquisition devices 7 can form an array of fiber optic induced polarization signal receiving and acquisition devices 7 in the well, and are connected to the instrument vehicle 6 on the ground through armored optoelectronic composite cable 28. The instrument vehicle 6 controls the array of in-well receiving and acquisition devices 7 through the armored optoelectronic composite cable 28, and transmits the in-well induced polarization data collected by the array of in-well receiving and acquisition devices 7 in real time through the armored optoelectronic composite cable 28.

[0052] Figure 2 This is a schematic diagram of an induced polarization logging instrument system and a ground-based long-wire transmitting structure, which is one of the implementation methods of an ionized fiber optic sensor.

[0053] Example 1

[0054] When there are multiple receiving and acquisition devices 7 in the well, the distance between adjacent receiving and acquisition devices 7 is 5 to 10 meters, and they are connected by armored optical fiber composite cable 28.

[0055] In one embodiment, the armored optoelectronic composite cable is provided with multiple optical fibers, each optical fiber being connected to a receiving and acquisition device 7 in the well.

[0056] In one embodiment, the armored optoelectronic composite cable contains an optical fiber that connects to multiple in-well receiving and acquisition devices 7, enabling multi-channel data acquisition and transmission through time-division and / or wavelength-division multiplexing technology.

[0057] When the multiple in-well receiving and acquisition devices 7 are used as an array, each pair of in-well receiving and acquisition devices 7 forms a pair of induced polarization signal measurement probes, and the potential signal difference of the primary or secondary field between each pair of in-well receiving and acquisition devices 7 is measured in sequence.

[0058] The waveform of the high-power square wave pulse excitation current 5 is a zero-duty half-duty bipolar square wave or a pseudo-random pulse sequence with a zero duty cycle and positive and negative polarities. The square wave period or unit pulse width is 0.01 to 64 s. Alternatively, the waveform of the high-power sine wave or cosine wave excitation current 5 is a sine wave or cosine wave with positive and negative peaks at different frequencies. A zero duty cycle means that the pulse signal contains only positive and negative pulse signals and there are no continuous pulse signals that are disconnected at zero.

[0059] The length of the grounding long wire 42 of the transmitting antenna 4 is 1000m to 5000m. The ground control device 30 of the high-power pulse or sine wave or cosine wave current transmitting source 1 alternately supplies power to the grounding long wire 42 in different directions through a reversing switch.

[0060] Example 2

[0061] Figure 3 This is a schematic diagram of the induced polarization logging instrument system and the square large loop transmitting coil of the plasma fiber optic sensor according to Embodiment 2. The side length of the square large loop transmitting coil 43 is 1000m to 5000m. When there are multiple receiving and acquisition devices 7 in the well, the distance between adjacent receiving and acquisition devices 7 is 5 meters to 10 meters, and they are connected by armored optical fiber composite cable 28.

[0062] Example 3

[0063] Figure 4 This is a schematic diagram of the induced polarization logging instrument system and the circular large loop transmitting coil structure of the plasma fiber optic sensor according to Embodiment 3. The diameter of the circular large loop transmitting coil 44 is 1000m to 5000m. When there are multiple in-well receiving and acquisition devices 7, the distance between adjacent in-well receiving and acquisition devices 7 is 5 meters to 10 meters, and they are connected by armored optical fiber composite cable 28.

[0064] The transmitting antenna in the well is a ring-shaped non-polarized transmitting electrode (46) with two excitation currents (5) at both ends of the fiber optic induced polarization signal receiving and acquisition device (7) installed in the well, or a three-component square transmitting coil (47) or a three-component ring transmitting coil (48) installed at one end of the fiber optic induced polarization signal receiving and acquisition device (7).

[0065] Figure 5This is a schematic diagram of the electrical source excitation and acquisition system for an induced polarization logging instrument based on a plasma fiber optic sensor. The transmitting antenna in the well is a ring-shaped non-polarized transmitting electrode 46 with two excitation currents 5 installed at both ends of the fiber optic induced polarization signal receiving and acquisition device 7 installed in the well. Figure 6 This is a schematic diagram of the structure of an electro-optical logging instrument electrical source excitation array acquisition system based on a plasma fiber optic sensor.

[0066] Figure 7 This is a schematic diagram of the structure of a square coil acquisition system excited by a magnetic source in an induced polarization logging instrument based on a plasma fiber optic sensor; Figure 8 This is a schematic diagram of a magnetic source-excited square coil array acquisition system for an induced polarization logging instrument based on a plasma fiber optic sensor. The transmitting antenna in the well is a three-component square transmitting coil 47 installed at one end of the fiber optic induced polarization signal receiving and acquisition device 7 installed in the well.

[0067] Figure 9 This is a schematic diagram of a magnetic source-excited circular coil acquisition system for an induced polarization logging instrument based on a plasma fiber optic sensor. Figure 10 This is a schematic diagram of a magnetic source-excited circular coil array acquisition system for an induced polarization logging instrument based on a plasma fiber optic sensor. The transmitting antenna in the well is a three-component circular coil 48 installed at one end of the fiber optic induced polarization signal receiving and acquisition device 7 installed in the well.

[0068] like Figure 6 , Figure 8 and Figure 10 As shown, the multiple in-well receiving and acquisition devices 7 can form an array of fiber optic induced polarization signal receiving and acquisition devices 7 in the well, and are connected to the instrument vehicle 6 on the ground through an armored optoelectronic composite cable 28. The instrument vehicle 6 controls the array of in-well receiving and acquisition devices 7 through the armored optoelectronic composite cable 28, and transmits the in-well induced polarization data collected by the plasma resonance fiber optic sensing probe 76 of the in-well receiving and acquisition devices 7 in real time through the armored optoelectronic composite cable 28.

[0069] like Figure 6 , Figure 8 and Figure 10 As shown, when there are multiple receiving and acquisition devices 7 in the well, the distance between adjacent receiving and acquisition devices 7 is 5 to 10 meters, and they are connected by armored optical fiber composite cable 28.

[0070] When in use, the array of in-well receiving and acquisition devices 7 is configured such that every two in-well receiving and acquisition devices 7 form a pair of induced polarization signal measurement probes, and the potential signal difference between the primary or secondary fields in the well between each pair of in-well receiving and acquisition devices 7 is measured sequentially.

[0071] The waveform of the high-power square wave pulse excitation current 5 on the ground or in the well is a zero-duty half-duty bipolar square wave or a pseudo-random pulse sequence with a zero duty cycle and positive and negative polarities, with a square wave period or unit pulse width of 0.01 to 64 s. Alternatively, the waveform of the high-power sine wave or cosine wave excitation current 5 on the ground or in the well is a sine wave or cosine wave with positive and negative peaks at different frequencies.

[0072] The ground transmitting antenna 4 has a grounding wire 42 with a length of 1000m to 5000m, the square large loop transmitting coil 43 has a side length of 1000m to 5000m, and the circular large loop transmitting coil 44 has a diameter of 1000m to 5000m.

[0073] The ground control device 30 of the ground high-power pulse excitation current or sine wave or cosine wave current transmitter 1 alternately supplies power to the grounding long conductors 42 in different directions through a reversing switch; or transmits sine wave or cosine wave excitation current 5 to the square large loop transmitter coil 43 or the circular large loop transmitter coil 44 surrounding the well.

[0074] The two annular non-polarized emitting electrodes 46 at both ends of the fiber optic induced polarization signal receiving and acquisition device 7 in the well are non-polarized electrodes, with a spacing between 1 meter and 5 meters. The well control device 31 of the pulse excitation current, sine wave, or cosine wave excitation current emitting source 2 in the well alternately supplies power to the two annular non-polarized emitting electrodes 46 through a reversing switch; or emits sine wave or cosine wave excitation current 5 to the three-component square emitting coil 47 or three-component annular emitting coil 48 installed at one end of the fiber optic induced polarization signal receiving and acquisition device 7.

[0075] The induced polarization logging instrument system and acquisition method based on plasma fiber optic sensors include the following steps:

[0076] S1. The ground control device 30 of the ground high-power pulse excitation current or sine wave or cosine wave excitation current transmitter 1 continuously transmits high-power square wave pulse excitation current or sine wave or cosine wave excitation current 5, which is supplied to the ground through the grounding electrode 41 of the transmitting antenna 4, or excites the ground through the square large loop transmitting coil 43 or the circular large loop transmitting coil 44 around the three-dimensional induced electromagnetic data acquisition well, so that the underground medium generates induced eddy currents, which gradually diffuse and attenuate into the half-space underground.

[0077] S2. The plasma resonance fiber optic sensing probe 76 in the well receiving and acquisition device 7 moves slowly from the bottom of the well to the wellhead and collects the ground-well time-domain or frequency-domain induced electric signals generated on the ground by the power supply current or induced eddy current continuously emitted by the ground control device 30 of the high-power pulse excitation current or sine wave or cosine wave excitation current transmitter 1 in step S1 at a certain point interval. Each measuring point measures and records 10 to 50 cycles of time-domain or frequency-domain induced electric signals.

[0078] S3, the GPS or Beidou timing and positioning module on the top of the instrument vehicle 6 on the ground provides timing for the ground-well time domain or frequency domain induced polarization signal collected by the receiving and acquisition device (7) in each well.

[0079] S4. The plasma resonance fiber optic sensing probe (76) array of the receiving and acquisition device (7) in the well transmits the ground-well time-domain or frequency-domain induced polarization signal acquired in step S2 to the fiber laser signal modulation and demodulation instrument (8) in the instrument vehicle (6) on the ground in real time through the armored optoelectronic composite cable (28). Then, it is converted into ground-well time-domain or frequency-domain induced polarization data at each measurement point through real-time modulation and demodulation processing. Finally, it is stored in the computer in the instrument vehicle (6).

[0080] S5. Process the ground-well time-domain induced polarization data from step S4 in the time domain to obtain the apparent polarization parameter (η) of the ground-well time-domain induced polarization at each measuring point. s The parameters of attenuation (D) and excitation ratio (J) are then used to extract mineral, lithological, reservoir, and fluid parameters related to the formation's electrical properties.

[0081] S6. The well control device 31 of the well pulse excitation current or sine wave or cosine wave excitation current transmitter 2 continuously and alternately transmits square wave pulse excitation current 5 to the two annular non-polarized transmitting electrodes 46 at both ends of the fiber optic induced polarization signal receiving and acquisition device 7 installed in the well through the well transmitting antenna, or transmits sine wave or cosine wave excitation current 5 to the three-component square transmitting coil 47 or three-component circular transmitting coil 48 installed at one end of the fiber optic induced polarization signal receiving and acquisition device 7, thereby exciting and inducing an electromagnetic field in the underground medium near the well receiving and acquisition device 7, causing the underground medium to generate induced eddy currents, which gradually diffuse and attenuate into the half-space underground.

[0082] S7. The plasma resonance fiber optic sensing probe 76 in the well-receiving and acquisition device 7 moves slowly from the bottom of the well to the wellhead and collects the well-time domain or frequency domain induced polarization signal generated in the well by the power supply current or induced eddy current continuously emitted by the well-pulse excitation current or sine wave or cosine wave excitation current emission source 2 in step S6 at a certain point interval. Each measuring point measures and records 10 to 50 cycles of well-time domain or frequency domain induced polarization signal.

[0083] S8. The GPS or Beidou timing and positioning module on the top of the instrument vehicle 6 on the ground provides timing for the time domain or frequency domain induced polarization signal collected by each well receiving and acquisition device 7 in each well.

[0084] S9. The plasma resonance fiber optic sensing probe 76 array of the receiving and acquisition device 7 in the well transmits the time-domain or frequency-domain induced polarization signal acquired in step S2 to the fiber laser signal modulation and demodulation instrument 8 in the instrument vehicle 6 on the ground in real time through the armored optical-electric composite cable 28. Then, it is converted into time-domain or frequency-domain induced polarization data of each measuring point location through real-time modulation and demodulation processing; finally, it is stored in the computer in the instrument vehicle 6.

[0085] S10. Process the in-well time-domain induced polarization data from step S9 in the time domain to obtain the apparent polarization parameter (η) of the in-well time-domain induced polarization at each measuring point. s The parameters of attenuation (D) and excitation ratio (J) are then used to extract mineral, lithological, reservoir, and fluid parameters related to the formation's electrical properties.

[0086] S11, the apparent polarizability η s This is a fundamental measurement parameter in DC (time-domain) induced polarization method, comprehensively reflecting the induced polarization effect of terrain and various polarimetric bodies within the current's range. The attenuation degree is a measurement parameter reflecting the rate of decay of the induced polarization field, expressed as a percentage. The faster the secondary field decays, the smaller its attenuation degree. The excitation ratio (J) is a comprehensive parameter combining apparent polarizability and attenuation degree.

[0087] S12. Process the ground-well frequency domain induced polarization data from step S4 or the well frequency domain induced polarization data from step S9 in the frequency domain to obtain the ground-well frequency domain induced polarization parameters or the well frequency domain induced polarization parameters and video divergence P at each measuring point. s , Apparent phase Φ s Apparent complex resistivity spectrum ρ s (iω), and then extract mineral, lithological, reservoir and fluid parameters related to the formation electrical properties;

[0088] S13, the video dispersion P s It is a fundamental measurement parameter in the AC (frequency domain) excited polarization method, and its expression is: P s =(ΔU(f) D )-ΔU(f G )) / ΔU(f D )×100%,ΔU(f D ), ΔU(f G ) represent the ultra-low frequency band (n×10) －2 ~n×10 2The total field potential difference formed by the low-frequency and high-frequency supply currents (Hz). And η s Similarly, P s It is also a comprehensive reflection of the topography and the polarization effect induced by various polaritons within the range of the current.

[0089] S14. Perform time-domain excitation polarization parameters and frequency-domain excitation polarization parameters of the ground-well or well obtained in steps S5, S10 and S12 on the ground-well or well to obtain the distribution of the time-domain complex resistivity or frequency-domain complex resistivity of the underground strata around the three-dimensional induced polarization data acquisition well in three-dimensional space.

[0090] S15. Based on the relationship between the distribution variation law of the formation time domain complex resistivity obtained by the time domain processing method and the formation frequency domain complex resistivity obtained by the frequency domain processing method, the distribution variation law of formation polarizability is obtained by inversion.

[0091] S16. Based on the distribution patterns, ranges, and characteristics of the complex resistivity and polarizability of underground strata, and through comprehensive interpretation combined with other geological, structural, petrological, mineral, and geoscientific information, the geoelectric characteristics of underground strata or rock units can be delineated, potential metal and non-metal mineral resource clusters or oil-water or gas-water boundaries of oil and gas resources can be delineated, and the distribution of highly polarizable minerals or oil and gas reservoirs in strata can be identified, predicted, comprehensively interpreted, and accurately evaluated.

[0092] All other parts not described in detail are existing technology.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Based on the technical essence of the present invention, any simple modifications, equivalent substitutions, and improvements made to the above embodiments within the spirit and principles of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An induced polarization logging instrument system based on a plasma fiber optic sensor, comprising a surface current transmitter (1), a borehole current transmitter (2), and at least one borehole receiving and acquisition device (7), characterized in that, The in-well receiving and acquisition device (7) is connected to an optical system for detecting induced polarization signals installed on the ground. The optical system consists of a broadband light source (72), a polarizer (73), a polarization controller (74), an optical fiber circulator (75), and a spectrometer (77) connected in sequence. The optical fiber circulator (75) is connected to the in-well receiving and acquisition device (7) and the spectrometer (77) respectively. The in-well receiving and acquisition device (7) is equipped with at least two plasma resonance optical fiber sensing probes (76), wherein: The plasma resonance fiber optic sensing probe (76) is used to collect the induced polarization signal in the well and transmit it through the armored optoelectronic composite cable (28) to the fiber laser signal modulation and demodulation instrument (8) for demodulation to obtain the induced polarization data in the well. The two plasma resonance fiber optic sensing probes in the well receiving and acquisition device (7) form a pair of well induced polarization signal measurement probes, or each pair of adjacent well receiving and acquisition devices (7) are connected by armored optoelectronic composite cable (28) to form a pair of well induced polarization signal measurement probes, used to measure the potential signal difference of the primary or secondary field in the well between each pair of induced polarization signal measurement probes. The ground current transmitter (1) is connected to the ground transmitting antenna (4) via a ground control device (30); The in-well current transmitting source (2) is installed in the in-well receiving and acquisition device (7) and is connected to the in-well transmitting antenna through the in-well control device (31) installed in the in-well receiving and acquisition device (7); The plasma resonance fiber optic sensing probe (76) is used to measure the induced polarization signal in the well during the emission of the excitation current (5); The ground transmitting antenna (4) consists of four grounded long wires (42) surrounding the well. The grounded long wires (42) are provided with grounding electrodes (41) at both ends. The ground current transmitting source (1) is used to alternately supply power to the grounded long wires (42) laid in different directions. The ground transmitting antenna (4) is a square large loop transmitting coil (43) or a circular large loop transmitting coil (44) surrounding the well.

2. The induced polarization logging instrument system based on a plasma fiber optic sensor according to claim 1, characterized in that, It also includes an instrument vehicle (6) on the ground, and the receiving and acquisition device (7) in the well is also connected to the instrument vehicle (6) via an armored optical-electric composite cable (28).

3. The induced polarization logging instrument system based on a plasma fiber optic sensor according to claim 1, characterized in that, There are multiple receiving and acquisition devices (7) in the well, and the distance between any two adjacent receiving and acquisition devices (7) in the well is 5-10m.

4. The induced polarization logging instrument system based on a plasma fiber optic sensor according to claim 1, characterized in that, The transmitting antenna in the well is a ring-shaped non-polarized transmitting electrode (46) installed at the upper and lower parts of the receiving and acquisition device (7) in the well. The current transmitting source (2) in the well is used to alternately supply power to the two ring-shaped non-polarized transmitting electrodes (46).

5. The induced polarization logging instrument system based on a plasma fiber optic sensor according to claim 1, characterized in that, The transmitting antenna in the well is a three-component square transmitting coil (47) or a three-component circular transmitting coil (48) installed in the upper part of the receiving and acquisition device (7) in the well.

6. A data acquisition method for an induced polarization logging instrument based on a plasma fiber optic sensor, applied in the induced polarization logging instrument system based on a plasma fiber optic sensor as described in claim 1, characterized in that... Includes the following steps: S1. Obtain ground-well induced polarization (PTD) data. The ground-well PTD data is obtained by modulating and demodulating the ground-well PTD signals collected by the plasma resonance fiber optic sensing probe (76) at each measuring point using a fiber laser signal modulator (8). The PTD signal is obtained by the well receiving and acquisition device (7) moving from the bottom of the well to the wellhead and collecting the ground-well PTD signal point by point at a preset distance after the ground current emission source (1) continuously emits a high-power excitation current into the ground. The ground-well PTD data includes ground-well time domain PTD data and ground-well frequency domain PTD data. S2. Obtaining well-induced polarization data, wherein the well-induced polarization data is obtained by modulating and demodulating the well-induced polarization signals collected by the plasma resonance fiber optic sensing probe (76) at each measuring point position using a fiber laser signal modulator (8). The well-induced polarization signals are obtained by the well-in-well receiving and acquisition device (7) moving from the bottom of the well to the wellhead and collecting the signals point by point at a preset distance after the well current emission source (2) continuously and alternately emits excitation current into the well. The well-in-well induced polarization data includes well-in-well time-domain induced polarization data and well-in-well frequency-domain induced polarization data. The ground-well time-domain induced polarization data or the well time-domain induced polarization data are used by the host computer to perform time-domain and frequency-domain inversion imaging to obtain three-dimensional induced polarization data. The three-dimensional induced polarization data is used to indicate the distribution pattern of the time-domain complex resistivity of the underground strata around the well in three-dimensional space, or the distribution pattern of the frequency-domain complex resistivity of the underground strata around the well in three-dimensional space. And by inverting the relationship between the time-domain complex resistivity and the frequency-domain complex resistivity, the distribution law of formation polarizability in three-dimensional space can be obtained; Based on the distribution patterns of the time-domain complex resistivity, frequency-domain complex resistivity, and polarizability of the underground strata in three-dimensional space, the geoelectric characteristics and induced polarization characteristics of the underground strata or rock units are determined.

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