Reservoir reconstruction evaluation system and monitoring method based on distributed optical fiber sensing technology

Abstract

The invention provides a reservoir transformation evaluation system and monitoring method based on a distributed optical fiber sensing technology, and the system employs a ground time-frequency electromagnetic data collection station, an armored spiral optical cable disposed outside a fracturing well section sleeve, and a ground high-power controllable current source. Two power supply electrodes which are connected to a wellhead casing pipe of a reservoir transformation well and are arranged below the ground at the far end several kilometers away from the ground projection line direction along the horizontal well track continuously and synchronously collect ground three-dimensional multi-component time-frequency electromagnetic data before fracturing starts, in the fracturing process and after fracturing ends. And inverting distribution of resistivity around the underground hydraulic fracturing well section at different fracturing stages. The fluid noise and temperature data of a fractured well section in the fracturing process are measured in real time through an armored optical cable, the water absorption profile or the fluid production profile of a reservoir transformation well section is calculated in an inversion mode, the reservoir transformation process and effect are monitored and evaluated in real time, reservoir transformation or hydraulic fracturing parameters are optimized and adjusted in real time, and the reservoir transformation effect is improved. And the effective reservoir transformation volume maximization is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of geophysical exploration, and in particular relates to a reservoir transformation evaluation system and a monitoring method based on distributed optical fiber sensing technology. Background Art

[0002] Time-frequency electromagnetic or transient electromagnetic method (TFEM) is a new method in the field of oil exploration. It uses a working method similar to large-offset seismic exploration to supply strong current to the earth to excite oil and gas exploration targets, and measure the secondary electromagnetic field and electromagnetic field spectrum formed by discharge in the porous medium of the oil and gas reservoir. This technology simultaneously obtains time domain and frequency domain signals, and through the joint processing of time domain and frequency domain signals, it accurately reconstructs the underground physical property model and obtains the resistivity and polarizability anomalies of the oil and gas exploration targets.

[0003] Time-frequency electromagnetic or transient electromagnetic technology combines frequency domain sounding and time domain sounding in one system. Different frequencies and different types of excitation waveforms can be selected according to the depth of the exploration target. It can not only provide resistivity information, but also provide induced polarization information. Therefore, it can detect its oil and gas content while studying the electrical structure. Time domain sounding processing uses pseudo-two-dimensional resistivity inversion to obtain resistivity information, and frequency domain sounding processing introduces the Cole-Cole model to extract induced polarization information. Time-frequency electromagnetic or transient electromagnetic method (TFEM) uses large devices to change the waveform length and frequency to perform sounding of targets at different depths.

[0004] The time-frequency electromagnetic or transient electromagnetic method field construction uses an equatorial dipole device, which is divided into two parts: transmitting and receiving. The transmitting field source consists of a number of parallel copper wires that form a wire source of limited length and grounded at both ends. A high-power time-frequency current source transmitter is used to send a series of square wave currents of different periods underground at different frequencies. The receiving end measures the electric field component E through the grounded dipole MN. X and E Y And high-sensitivity magnetic rod to measure the vertical magnetic induction component (dB Z / dt).

[0005] At present, reservoir transformation is mainly based on hydraulic or carbon dioxide fracturing technology. Real-time monitoring of reservoir transformation or hydraulic fracturing process is mostly based on underground, ground and shallow well microseismic monitoring technology. When the horizontal well is deep (more than 2500 meters), the ground or shallow well microseismic monitoring technology can only receive microseismic events with larger magnitude or energy because the ground or shallow well detectors are too far away from the fracturing well section. The microseismic events it can monitor are much less than those monitored by the underground microseismic monitoring system of the monitoring well next to the fracturing well, and it cannot monitor the actual extension range of rock fractures caused by hydraulic fracturing in real time. In addition, the microseismic events caused by hydraulic fracturing are not necessarily caused by further rock fractures during the extension of fractures. Therefore, the size of the reservoir remodeled volume (SRV) defined by the envelope range of the distribution of microseismic events in the three-dimensional underground space is often inconsistent with the production capacity after horizontal well fracturing, indicating that there are many locations where microseismic events occur without actual connectivity of the fracture network. Therefore, the effective remodeled volume (ESRV) is defined based on the actual volume of the effectively connected fracture network, and it is found that the ESRV is well correlated with the production capacity of the horizontal well section of the fracture. Summary of the invention

[0006] In order to solve the problems existing in the hydraulic fracturing microseismic monitoring technology in real-time evaluation of fracturing effect and calculation of effective transformed volume (ESRV), the present invention proposes a reservoir transformation evaluation system and monitoring method based on distributed optical fiber sensing technology, which utilizes a three-dimensional multi-component ground time-frequency electromagnetic data acquisition station arranged on the ground above the fracturing well section in the horizontal well, and an armored spiral optical cable arranged outside the casing of the fracturing well section, to connect a large current emitting electrode of a ground high-power controllable current source to the wellhead casing of the reservoir transformation well, and another large current emitting electrode is arranged below the far ground several kilometers away in the direction of the ground projection line along the horizontal well trajectory, and continuously monitors the reservoir transformation before, during and after the fracturing. The ground three-dimensional multi-component time-frequency electromagnetic data, fluid noise and temperature data of the fracturing well section are collected synchronously, and the difference between the three-dimensional multi-component time-frequency electromagnetic data collected during and after fracturing and the three-dimensional multi-component time-frequency electromagnetic data collected before fracturing is calculated in real time. At the same time, the distribution of resistivity around the underground hydraulic fracturing well section at different fracturing stages is inverted according to the measured ground three-dimensional multi-component time-frequency electromagnetic or data. The distribution change characteristics of the resistivity around the underground hydraulic fracturing well section at different fracturing stages are used to evaluate the fracturing effect in real time, and the effective transformed volume (ESRV) is calculated using the envelope of the resistivity distribution around the underground hydraulic fracturing well section inverted from the ground three-dimensional multi-component time-frequency electromagnetic data measured after fracturing. At the same time, the armored spiral optical cable laid outside the casing of the fracturing section is used to measure the fluid noise and temperature data of the fracturing section in real time, and the water absorption profile or liquid production profile of the reservoir transformation or hydraulic fracturing section is inverted and calculated, and the effect of the reservoir transformation is evaluated in real time. According to the real-time evaluation results, the reservoir transformation or hydraulic fracturing parameters are optimized and adjusted in real time to maximize the effective reservoir transformation volume (ESRV).

[0007] The specific technical solutions are:

[0008] Reservoir transformation evaluation system based on distributed optical fiber sensing technology, including: armored optical cable, perforating bullets, ground time-frequency electromagnetic data acquisition station, ground high-power controllable current source;

[0009] The armored optical cable is spirally fixed on the outside of the casing of the reservoir transformation well section; the perforating bullet is embedded in the outer wall of the casing of the reservoir transformation well section;

[0010] The ground time-frequency electromagnetic data acquisition station is a ground wired or wireless node-type time-frequency electromagnetic data acquisition station, which is arranged in a three-dimensional manner on the ground above the horizontal well fracturing section;

[0011] The ground time-frequency electromagnetic data acquisition station is connected to the time-frequency electromagnetic data acquisition system or distributed optical fiber sensing modulation and demodulation instrument in the work area or near the wellhead through a cable; the cable is an electric cable or an optoelectronic composite cable;

[0012] The distributed optical fiber sensing modulation and demodulation instrument is a DAS / DTS / DSS composite distributed optical fiber sensing modulation and demodulation instrument;

[0013] A large current emitting electrode of the ground high-power controllable current source is connected to the wellhead casing of the reservoir transformation well, and another large current emitting electrode is arranged below the far ground several kilometers away in the direction of the ground projection line along the horizontal well trajectory.

[0014] The ground high-power controllable current source is a high-power dipole current source.

[0015] The ground time-frequency electromagnetic data acquisition station comprises a wired or wireless node-type electromagnetic data acquisition unit, a three-component magnetic field sensor and a pair of non-polarized electric field sensors arranged according to pre-designed survey lines and survey points.

[0016] The three-component magnetic field sensor is one of an induction coil magnetic field sensor, a fluxgate magnetic field sensor, a MEMS magnetic field sensor, a superconducting magnetic field sensor or an optical fiber magnetic field sensor; the non-polarized electric field sensor pair is one of copper sulfate, silver chloride, nanomaterials, tantalum capacitor non-polarized electrode pairs or optical fiber electric field sensor pairs.

[0017] The outer wall surface of the casing of the reservoir transformation well section is engraved with a semicircular groove for laying the armored optical cable by mechanical processing. The width of the semicircular groove is the same as the diameter of the armored optical cable, and the depth of the semicircular groove is the same as the diameter of the armored optical cable.

[0018] The armored optical cable includes two optical units, namely a first optical unit and a second optical unit. The first optical unit includes a high-temperature resistant, high-sensitivity, high-reflectivity single-mode optical fiber and a high-temperature resistant, high-sensitivity, high-reflectivity multi-mode optical fiber, and the second optical unit includes a high-temperature resistant, high-sensitivity, high-reflectivity strain-sensitive optical fiber.

[0019] The perforating bullets are designed and processed on the outer wall of the casing of the reservoir transformation well section according to the perforating bullet distribution requirements to install the perforating bullets, and the perforating bullets are embedded and fixed in the conical holes.

[0020] A monitoring method for a reservoir transformation evaluation system based on distributed optical fiber sensing technology, using the reservoir transformation evaluation system based on distributed optical fiber sensing technology; the monitoring method comprises the following steps:

[0021] (a) After the drilling operation of the reservoir transformation well is completed, the reservoir transformation well section casing with the spiral armored optical cable embedded and fixed on the outside and the perforating bullet installed in the outer wall is lowered to the bottom of the well in sequence;

[0022] (b) high-pressure cement slurry is injected into the well from the bottom of the well using a drill pipe. The high-pressure cement slurry squeezes the drilling fluid or drilling mud out of the wellhead along the annulus between the well wall and the outer wall of the casing of the reservoir transformation well section from the bottom of the well, and fills the annulus between the well wall and the outer wall of the casing of the reservoir transformation well section. After the cement slurry solidifies, the casing of the reservoir transformation well section and the well wall are consolidated into one, thus completing the cementing operation;

[0023] (c) connecting the head end of the spiral armored optical cable outside the casing to a distributed optical fiber sensing modem instrument near the wellhead;

[0024] (d) arranging a ground time-frequency electromagnetic data acquisition station on the ground above the horizontal well fracturing section in a pre-designed three-dimensional manner, and connecting the ground time-frequency electromagnetic data acquisition station to a time-frequency electromagnetic data acquisition system or a distributed optical fiber sensing modulation and demodulation instrument through a cable;

[0025] (e) Connect a large current emitting electrode of a ground high-power controllable current source to the wellhead casing of the reservoir transformation well, and arrange another large current emitting electrode below the ground at a remote end several kilometers away in the direction of the ground projection line along the horizontal well trajectory, and do a good job of reducing the ground resistance at the remote ground end of the large current emitting electrode;

[0026] (f) starting a high-power controllable current source on the ground and continuously emitting a forward and reverse high-power square wave current with a duty cycle of 0.05 to 0.05 from the casing opening and the high-current emitting electrode below the far end of the ground through the high-current emitting electrodes connected at both ends;

[0027] (g) Start the time-frequency electromagnetic data acquisition system and the ground time-frequency electromagnetic data acquisition station to continuously collect three-dimensional multi-component ground time-frequency electromagnetic data in real time;

[0028] (h) starting a distributed optical fiber sensing modem instrument near the surface wellhead to continuously collect downhole noise, temperature and strain signals distributed along the armored optical cable received by the armored optical cable spirally laid outside the casing of the reservoir transformation well section in real time;

[0029] (g) emitting a high current pulse current signal through the casing opening to the underground casing, which can trigger the electrically excited primer of the perforating bullet embedded in the outer wall of the casing in the reservoir transformation well section, thereby triggering the perforating bullet to perform perforation operations in the formation outside the casing;

[0030] (h) subsequently injecting high-pressure fracturing fluid into the reservoir reforming section of the wellbore along the perforation points, forcing the reservoir to begin to fracture from the perforation points and generate a fracture network that gradually expands to the outer formation of the wellbore wall, and at the same time adding sand or ceramsite proppants to the fracturing fluid so that the reformed fracture network can support and keep the fractures open when the fracturing fluid is discharged and discharged;

[0031] (i) Using distributed optical fiber sensing modulation and demodulation instruments to continuously collect and demodulate downhole noise, temperature and strain data distributed along the armored optical cable in real time, real-time monitoring of the firing status of perforating bullets on the outer wall of the casing of the reservoir transformation well section, the injection and return flow rate of the fracturing fluid along the perforation points, and the distribution and change of ground stress along the outer line of the casing of the reservoir transformation well section;

[0032] (j) real-time processing of time-frequency electromagnetic data collected by a ground time-frequency electromagnetic data acquisition station arranged in a three-dimensional manner above the horizontal well fracturing section, and calculation of the resistivity distribution and temporal changes of the reservoir outside the casing of the reservoir transformation section by a three-dimensional inversion method;

[0033] (k) comprehensively interpreting the data processing results of step (i) and step (j), evaluating in real time the progress of underground reservoir transformation, including the excitation of perforating bullets, perforation effect, flow rate and injection volume or flowback volume of fracturing fluid, expansion speed and expansion spatial range of fractures around the reservoir transformation well section, fracture connectivity and envelope volume of connected fracture bodies or effective reservoir transformation volume, optimizing and adjusting reservoir transformation parameters in real time to achieve the best reservoir transformation effect;

[0034] (l) During the production process of oil and gas production wells after reservoir transformation, the downhole noise and temperature data distributed along the armored optical cable are continuously measured and demodulated in real time using a distributed optical fiber sensor modulation and demodulation instrument to calculate the liquid production profile of the oil and gas production well; the distribution and changes of formation stress along the outer casing of the reservoir transformation well section are measured in real time to monitor the status of the casing of the reservoir transformation well section in real time and over a long period of time, to warn and prevent the occurrence of casing damage along the casing of the reservoir transformation well section, and to ensure the long-term stable and high production of the oil and gas production wells.

[0035] The monitoring method of the reservoir transformation evaluation system based on the distributed optical fiber sensing technology provided by the present invention can be used to monitor reservoir transformation or hydraulic fracturing operations in real time, optimize fracturing parameters in real time, and evaluate the final fracturing effect.

[0036] Beneficial effects of the present invention: The present invention proposes a monitoring method for a reservoir transformation evaluation system based on distributed optical fiber sensing technology, which utilizes a three-dimensional multi-component ground time-frequency electromagnetic data acquisition station arranged on the ground above a fracturing well section in a horizontal well, an armored spiral optical cable arranged outside the casing of the fracturing well section, a ground high-power controllable current source, and two power supply electrodes connected to the wellhead casing of the reservoir transformation well and arranged below the far end ground several kilometers away in the direction of the ground projection line along the horizontal well trajectory. Before, during and after fracturing, the ground three-dimensional multi-component time-frequency electromagnetic data, fluid noise and temperature data of the fracturing well section are continuously and synchronously collected, the distribution of resistivity around the underground hydraulic fracturing well section during and after fracturing is calculated in real time, the distribution change characteristics of the resistivity around the underground hydraulic fracturing well section at different fracturing stages are used to evaluate the fracturing effect in real time, and the effective transformed volume (ESRV) is calculated by using the envelope of the distribution of resistivity around the underground hydraulic fracturing well section inverted from the ground three-dimensional multi-component time-frequency electromagnetic data measured after the fracturing is completed. At the same time, the armored spiral optical cable laid outside the casing of the fracturing section is used to measure the fluid noise and temperature data of the fracturing section in real time, and the water absorption profile or liquid production profile of the reservoir transformation or hydraulic fracturing section is inverted and calculated, and the effect of the reservoir transformation is evaluated in real time. According to the real-time evaluation results, the reservoir transformation or hydraulic fracturing parameters are optimized and adjusted in real time to maximize the effective reservoir transformation volume (ESRV). BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the ground wired time-frequency electromagnetic acquisition station and the underground armored spiral optical cable monitoring system of the present invention.

[0038] Figure 2 It is a schematic diagram of the ground wireless node-type time-frequency electromagnetic acquisition station and the underground armored spiral optical cable monitoring system of the present invention.

[0039] Figure 3 It is a structural schematic diagram of the ground electronic wired time-frequency electromagnetic acquisition station of the present invention.

[0040] Figure 4 It is a structural schematic diagram of a ground time-frequency electromagnetic acquisition station based on optical fiber three-component magnetic field and optical fiber three-component electric field sensors of the present invention.

[0041] Figure 5 The present invention is a schematic diagram of a casing structure in which a spiral armored optical cable and a perforating bullet are embedded outside a reservoir transformation well section. DETAILED DESCRIPTION

[0042] To facilitate those skilled in the art to understand the technical content of the present invention, the present invention is further explained below with reference to the accompanying drawings.

[0043] Figure 1 and Figure 2Schematic diagram of the ground wired and wireless node-type time-frequency electromagnetic acquisition station and the underground armored spiral optical cable monitoring system of the present invention. Figure 1 and Figure 2 As shown, a reservoir transformation evaluation system based on distributed optical fiber sensing technology includes: an armored optical cable 2, a perforating bullet 3, a ground time-frequency electromagnetic data acquisition station 5, and a ground high-power controllable current source 7;

[0044] The armored optical cable 2 is spirally fixed on the outside of the reservoir transformation well section casing 1; the perforating bullet 3 is embedded in the outer wall of the reservoir transformation well section casing 1;

[0045] The ground time-frequency electromagnetic data acquisition station 5 is a ground wired or wireless node-type time-frequency electromagnetic data acquisition station, which is arranged in a three-dimensional manner on the ground above the horizontal well fracturing section;

[0046] The ground time-frequency electromagnetic data acquisition station 5 is connected to the time-frequency electromagnetic data acquisition system 6 or the distributed optical fiber sensing modulation and demodulation instrument 4 in the work area or near the wellhead through a cable 9; the cable 9 is an electric cable or an optoelectronic composite cable;

[0047] The distributed optical fiber sensing modulation and demodulation instrument 4 is a DAS / DTS / DSS composite distributed optical fiber sensing modulation and demodulation instrument;

[0048] One high current emitting electrode 8 of the ground high power controllable current source 7 is connected to the wellhead casing of the reservoir transformation well, and another high current emitting electrode 8 is arranged below the far ground several kilometers away in the direction of the ground projection line along the horizontal well trajectory.

[0049] The ground high-power controllable current source 7 is a high-power dipole current source. The ground time-frequency electromagnetic data acquisition station 5 comprises a wired or wireless node-type time-frequency electromagnetic data acquisition unit 10, a three-component magnetic field sensor 11 and a non-polarized electric field sensor pair 12 arranged according to the pre-designed measurement lines and measurement points.

[0050] Figure 3 and Figure 4 It is a schematic diagram of the structure of the ground electronic and wired time-frequency electromagnetic acquisition station based on optical fiber three-component magnetic field and optical fiber three-component electric field sensors of the present invention. The three-component magnetic field sensor 11 is one of an induction coil magnetic field sensor, a fluxgate magnetic field sensor, a MEMS magnetic field sensor, a superconducting magnetic field sensor, and an optical fiber magnetic field sensor; the non-polarized electric field sensor pair 12 is one of copper sulfate, silver chloride, nanomaterials, tantalum capacitor non-polarized electrode pairs, and optical fiber electric field sensor pairs.

[0051] Figure 5The present invention is a schematic diagram of a casing structure in which a spiral armored optical cable and a perforating bullet are embedded outside a reservoir transformation well section. The outer wall surface of the reservoir transformation well section casing 1 is engraved with a semicircular groove 13 for laying a spiral armored optical cable 2 by mechanical processing, and the diameter of the semicircular groove 13 is the same as the diameter of the armored optical cable 2, and the depth of the semicircular groove (13) is the same as the diameter of the armored optical cable 2.

[0052] The armored optical cable 2 includes two optical units, namely a first optical unit 14 and a second optical unit 15. The first optical unit 14 includes a high-temperature resistant, high-sensitivity, high-reflection coefficient single-mode optical fiber and a high-temperature resistant, high-sensitivity, high-reflection coefficient multimode optical fiber. The second optical unit 15 includes a high-temperature resistant, high-sensitivity, strain-sensitive optical fiber.

[0053] The perforating bullets 3 are designed and processed on the outer wall of the casing 1 of the reservoir transformation well section according to the perforating bullet distribution requirements to form conical holes 16 for installing the perforating bullets, and the perforating bullets 3 are embedded and fixed in the conical holes 16.

[0054] The monitoring method of the reservoir transformation evaluation system based on distributed optical fiber sensing technology comprises the following steps:

[0055] (a) After the drilling operation of the reservoir transformation well is completed, the reservoir transformation well section casing 1 with the spiral armored optical cable 2 embedded and fixed on the outside and the perforating bullet 3 installed in the outer wall is sequentially lowered to the bottom of the well;

[0056] (b) high-pressure cement slurry is injected into the well from the bottom of the well using a drill pipe. The high-pressure cement slurry squeezes the drilling fluid or drilling mud out of the wellhead along the annulus between the well wall and the outer wall of the casing 1 of the reservoir transformation well section from the bottom of the well, and fills the annulus between the well wall and the outer wall of the casing 1 of the reservoir transformation well section. After the cement slurry solidifies, the casing 1 of the reservoir transformation well section and the well wall are consolidated into one, thereby completing the cementing operation;

[0057] (c) connecting the head end of the spiral armored optical cable outside the casing to a distributed optical fiber sensing modem instrument 4 near the wellhead;

[0058] (d) the ground time-frequency electromagnetic data acquisition station 5 is arranged on the ground above the horizontal well fracturing section in a pre-designed three-dimensional manner, and the ground time-frequency electromagnetic data acquisition station 5 is connected to the time-frequency electromagnetic data acquisition system 6 or the distributed optical fiber sensing modulation and demodulation instrument 4 through the cable 9;

[0059] (e) connecting a large current emitting electrode 8 of the ground high-power controllable current source 7 to the wellhead casing of the reservoir transformation well, and arranging another large current emitting electrode 8 below the far ground several kilometers away in the direction of the ground projection line along the horizontal well trajectory, and making good treatment on the far ground end of the large current emitting electrode 8 to reduce the ground resistance;

[0060] (f) starting the ground high-power controllable current source 7 and continuously emitting forward and reverse high-power square wave currents with a duty cycle of 1 from the casing opening and the high-current emitting electrodes 8 below the far end of the ground to the underground through the high-current emitting electrodes 8 connected at both ends;

[0061] (g) starting the ground time-frequency electromagnetic data acquisition control system 6 and the ground time-frequency electromagnetic data acquisition station 5 to continuously acquire the ground three-dimensional multi-component time-frequency electromagnetic data in real time;

[0062] (h) starting a distributed optical fiber sensing modem instrument 4 near the surface wellhead to continuously collect downhole noise, temperature and strain signals distributed along the armored optical cable 2 spirally arranged outside the casing 1 of the reservoir transformation well section in real time;

[0063] (g) a high current pulse current signal is emitted through the casing opening to the underground casing, which can trigger the electric excitation primer of the perforating bullet 3 embedded in the outer wall of the casing 1 of the reservoir transformation well section, so as to trigger the perforating bullet to perform perforation operation on the formation outside the casing;

[0064] (h) subsequently injecting high-pressure fracturing fluid into the reservoir reforming section of the wellbore along the perforation points, forcing the reservoir to begin to fracture from the perforation points and generate a fracture network that gradually expands to the outer formation of the wellbore wall, and at the same time adding sand or ceramsite proppants to the fracturing fluid so that the reformed fracture network can support and keep the fractures open when the fracturing fluid is discharged and discharged;

[0065] (i) using the ground distributed optical fiber sensing modulation and demodulation instrument 4 to continuously collect and demodulate the downhole noise, temperature and strain data distributed along the armored optical cable 2 in real time, and to monitor in real time the perforation firing state of the perforating bullet 3 on the outer wall of the casing 1 of the reservoir transformation well section, the injection and return flow rate of the fracturing fluid along the perforation point, and the distribution and change of the ground stress along the outer line of the casing 1 of the reservoir transformation well section;

[0066] (j) real-time processing of time-frequency electromagnetic data collected by a ground time-frequency electromagnetic data collection station 5 arranged in a three-dimensional manner above the ground above the horizontal well fracturing section, and calculation of the resistivity distribution and time-varying changes of the reservoir outside the casing 1 of the reservoir transformation section by a three-dimensional inversion method;

[0067] (k) comprehensively interpreting the data processing results of step (i) and step (j), evaluating the progress of underground reservoir transformation in real time, including the excitation of perforating bullets, perforation effect, flow rate and injection volume or flowback volume of fracturing fluid, expansion speed and expansion space range of fractures around the reservoir transformation well section, fracture connectivity and envelope volume of connected fracture bodies or effective reservoir transformation volume (ESRV), etc., optimizing and adjusting reservoir transformation parameters in real time to achieve the best reservoir transformation effect;

[0068] (l) During the production process of the oil and gas production well after the reservoir transformation, the downhole noise and temperature data distributed along the armored optical cable 2 can be measured and demodulated in real time by the ground distributed optical fiber sensor modulation and demodulation instrument 4, and the production profile of the oil and gas production well can be calculated. The distribution and change of the formation stress measured in real time along the outer line of the casing 1 of the reservoir transformation well section can be used to monitor the state of the casing 1 of the reservoir transformation well section in real time and for a long time, and the casing damage along the casing 1 of the reservoir transformation well section can be warned and prevented, so as to ensure the long-term stable and high production of the oil and gas production well.

Claims

1. A reservoir transformation evaluation system based on distributed optical fiber sensing technology, characterized in that: include: Armored optical cable (2), perforating bullet (3), ground time-frequency electromagnetic data acquisition station (5), ground high-power controllable current source (7); The armored optical cable (2) is spirally fixed on the outside of the reservoir transformation well section casing (1); the perforating bullet (3) is embedded in the outer wall of the reservoir transformation well section casing (1); The ground time-frequency electromagnetic data acquisition station (5) is a ground wired or wireless node-type time-frequency electromagnetic data acquisition station, which is arranged in a three-dimensional manner on the ground above the horizontal well fracturing section; The ground time-frequency electromagnetic data acquisition station (5) is connected to a time-frequency electromagnetic data acquisition system (6) or a distributed optical fiber sensing modulation and demodulation instrument (4) in a work area or near a wellhead via a cable (9); the cable (9) is an electric cable or an optoelectronic composite cable; The distributed optical fiber sensing modulation and demodulation instrument (4) is a DAS / DTS / DSS composite distributed optical fiber sensing modulation and demodulation instrument; A large current emitting electrode (8) of the ground large-power controllable current source (7) is connected to the wellhead casing of the reservoir transformation well, and another large current emitting electrode (8) is arranged below the far ground several kilometers away in the direction of the ground projection line along the horizontal well trajectory.

2. The reservoir transformation evaluation system based on distributed optical fiber sensing technology according to claim 1 is characterized in that: The ground high-power controllable current source (7) is a high-power dipole current source.

3. The reservoir transformation evaluation system based on distributed optical fiber sensing technology according to claim 1 is characterized in that: The ground time-frequency electromagnetic data acquisition station (5) comprises a wired or wireless node-type time-frequency electromagnetic data acquisition unit (10), a three-component magnetic field sensor (11), and a non-polarized electric field sensor pair (12) arranged according to pre-designed measurement lines and measurement points.

4. The reservoir transformation evaluation system based on distributed optical fiber sensing technology according to claim 3 is characterized in that: The three-component magnetic field sensor (11) is one of an induction coil magnetic field sensor, a fluxgate magnetic field sensor, a MEMS magnetic field sensor, a superconducting magnetic field sensor or an optical fiber magnetic field sensor; the non-polarized electric field sensor pair (12) is one of copper sulfate, silver chloride, nanomaterials, a tantalum capacitor non-polarized electrode pair or an optical fiber electric field sensor pair.

5. The reservoir transformation evaluation system based on distributed optical fiber sensing technology according to claim 1 is characterized in that: The outer wall surface of the reservoir transformation well section casing (1) is engraved with a semicircular groove (13) for laying the armored optical cable (2) by mechanical processing, the width of the semicircular groove (13) is the same as the diameter of the armored optical cable (2), the depth of the semicircular groove (13) is the same as the diameter of the armored optical cable (2), and the angle between the semicircular groove (13) and the extension direction of the reservoir transformation well section casing (1) is between 20 degrees and 70 degrees.

6. The reservoir transformation evaluation system based on distributed optical fiber sensing technology according to claim 1 is characterized in that: The armored optical cable (2) comprises two optical units, namely a first optical unit (14) and a second optical unit (15); the first optical unit (14) comprises a high temperature resistant, high sensitivity, high reflection coefficient single-mode optical fiber and a high temperature resistant, high sensitivity, high reflection coefficient multi-mode optical fiber; the second optical unit (15) comprises a high temperature resistant, high sensitivity, high reflection coefficient strain sensitive optical fiber.

7. The reservoir transformation evaluation system based on distributed optical fiber sensing technology according to claim 1 is characterized in that: The perforating bullet (3) is designed and processed on the outer wall of the casing (1) of the reservoir transformation well section according to the perforating bullet distribution requirements to form a conical hole (16) for installing the perforating bullet, and the perforating bullet (3) is embedded and fixed in the conical hole (16).

8. A monitoring method for a reservoir transformation evaluation system based on distributed optical fiber sensing technology, characterized in that: A reservoir reconstruction evaluation system based on distributed optical fiber sensing technology as described in any one of claims 1 to 7; the monitoring method comprises the following steps: (a) After the drilling operation of the reservoir transformation well is completed, the reservoir transformation well section casing (1) with the spiral armored optical cable (2) embedded and fixed on the outside and the perforating bullet (3) installed in the outer wall is successively lowered to the bottom of the well; (b) injecting high-pressure cement slurry from the bottom of the well into the well using a drill pipe, the high-pressure cement slurry squeezes the drilling fluid or drilling mud out of the wellhead along the annulus between the well wall and the outer wall of the casing (1) of the reservoir transformation well section from the bottom of the well, and fills the annulus between the well wall and the outer wall of the casing (1) of the reservoir transformation well section, and after the cement slurry solidifies, the casing (1) of the reservoir transformation well section and the well wall are consolidated into one, thereby completing the cementing operation; (c) connecting the head end of the spiral armored optical cable outside the casing to a distributed optical fiber sensing modem instrument (4) near the wellhead; (d) arranging the ground time-frequency electromagnetic data acquisition station (5) on the ground above the horizontal well fracturing section in a pre-designed three-dimensional manner, and connecting the ground time-frequency electromagnetic data acquisition station (5) to the time-frequency electromagnetic data acquisition system (6) or the distributed optical fiber sensing modulation and demodulation instrument (4) through a cable (9); (e) connecting a large current emitting electrode (8) of a ground large-power controllable current source (7) to the wellhead casing of the reservoir transformation well, and arranging another large current emitting electrode (8) below the ground at a far end several kilometers away in the direction of the ground projection line along the horizontal well trajectory, and performing treatment on the far end grounding end of the large current emitting electrode (8) to reduce the grounding resistance; (f) starting a high-power controllable current source (7) on the ground and continuously emitting a forward and reverse high-power square wave current with a duty cycle of 1 from the casing opening and the high-current emitting electrode (8) below the far end of the ground to the underground through a high-current emitting electrode (8) connected at both ends; (g) starting the time-frequency electromagnetic data acquisition system (6) and the ground time-frequency electromagnetic data acquisition station (5) to continuously acquire the ground three-dimensional multi-component time-frequency electromagnetic data in real time; (h) starting a distributed optical fiber sensing modem instrument (4) near the surface wellhead to continuously collect downhole noise, temperature and strain signals distributed along the armored optical cable (2) spirally arranged outside the casing (1) of the reservoir transformation well section in real time; (g) emitting a high current pulse current signal through the casing opening to the underground casing, which can trigger the electrically excited primer of the perforating bullet (3) embedded in the outer wall of the casing (1) of the reservoir transformation well section, thereby triggering the perforating bullet to perform perforation operation on the formation outside the casing; (h) subsequently injecting high-pressure fracturing fluid into the reservoir reforming section of the wellbore along the perforation points, forcing the reservoir to begin to fracture from the perforation points and generate a fracture network that gradually expands to the outer formation of the wellbore wall, and at the same time adding sand or ceramsite proppants to the fracturing fluid so that the reformed fracture network can support and keep the fractures open when the fracturing fluid is discharged and discharged; (i) using a distributed optical fiber sensing modulation and demodulation instrument (4) to continuously collect and demodulate downhole noise, temperature and strain data distributed along the armored optical cable (2) in real time, to monitor in real time the firing state of the perforating bullet (3) on the outer wall of the reservoir transformation well section casing (1), the injection and return flow rate and flow rate of the fracturing fluid along the perforation points, the expansion and extension state of the fracture grid into the outer stratum of the reservoir transformation well section casing (1), and the distribution and change of ground stress along the outer line of the reservoir transformation well section casing (1); (j) real-time processing of time-frequency electromagnetic data collected by a data acquisition station (5) arranged in a three-dimensional manner above the horizontal well fracturing section, and rapid calculation of the resistivity distribution and temporal changes of the reservoir outside the casing (1) of the reservoir transformation section by a three-dimensional inversion method; (k) comprehensively interpreting the data processing results of step (i) and step (j), evaluating in real time the progress of underground reservoir transformation, including the firing of perforating bullets, perforation effect, flow rate and injection volume or flowback volume of fracturing fluid, expansion speed and spatial range of fractures in the formations around the reservoir transformation well section, fracture connectivity and envelope volume of connected fracture bodies or effective reservoir transformation volume, optimizing and adjusting reservoir transformation parameters in real time to achieve the best reservoir transformation effect; (l) During the production process of an oil and gas production well after reservoir transformation, the downhole noise and temperature data distributed along the armored optical cable (2) are continuously measured and demodulated by a distributed optical fiber sensing modulation and demodulation instrument (4) in real time to calculate the liquid production profile of the oil and gas production well; the distribution and change of the formation stress measured in real time along the outer line of the reservoir transformation well section casing (1) are used to monitor the state of the reservoir transformation well section casing (1) in real time for a long time, warn and prevent the occurrence of casing damage along the reservoir transformation well section casing (1), and ensure the long-term stable and high production of the oil and gas production well.

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