阅读说明：本技术 井下长期动态监测特种分布式铠装光缆和监测系统及方法 (Special distributed armored optical cable for underground long-term dynamic monitoring and monitoring system and method ) 是由 余刚 安树杰 张仁志 王熙明 冉曾令 夏淑君 于 2020-07-09 设计创作，主要内容包括：本发明提出了一种井下长期动态监测特种分布式铠装光缆和监测系统及方法,井下长期动态监测特种分布式铠装光缆,特种应变和震动或噪声测量光缆和通用型温度和震动或噪声测量光缆的两侧都有承压抗磨加强筋进行保护,五者构成的扁平状结构外侧有铠装钢丝构成的保护外套。特种分布式铠装光缆固定在金属套管外侧；特种分布式铠装光缆尾端含有消光器件,上端连接DSS/DAS/DTS复合调制解调仪器。把特种分布式铠装光缆捆绑在垂直井、斜井或水平井套管外侧并用固井水泥永久性固定,长期实时监测地下应力对井下套管可能造成的损害或破坏。同时获取每口油气生产井和注水或注液井的产液剖面或吸水剖面,实现对生产井或注液驱替井在生产过程中变化规律的长期动态监测。(The invention provides a special distributed armored optical cable for underground long-term dynamic monitoring, a monitoring system and a monitoring method. The special distributed armored optical cable is fixed on the outer side of the metal sleeve; the tail end of the special distributed armored optical cable comprises an extinction device, and the upper end of the special distributed armored optical cable is connected with a DSS/DAS/DTS composite modulation and demodulation instrument. The special distributed armored optical cable is bound on the outer side of a vertical well, an inclined well or a horizontal well casing and is permanently fixed by using well cementation cement, and the damage or damage possibly caused by underground stress to the underground casing is monitored in real time for a long time. And meanwhile, the liquid production profile or the water absorption profile of each oil and gas production well and the water injection or liquid injection well is obtained, so that the long-term dynamic monitoring of the change rule of the production well or the liquid injection displacement well in the production process is realized.)

1. The underground long-term dynamic monitoring special distributed armored optical cable is characterized by comprising a special high-temperature-resistant strain and vibration or noise measuring optical cable (1), a universal high-temperature-resistant temperature and vibration or noise measuring optical cable (2), three groups of pressure-bearing anti-wear reinforcing ribs (3), the special strain and vibration or noise measuring optical cable (1) and the universal temperature and vibration or noise measuring optical cable (2) are arranged in parallel, the three groups of pressure-bearing anti-wear reinforcing ribs (3) are respectively positioned on two sides and in the middle of the special strain and vibration or noise measuring optical cable (1) and the universal temperature and vibration or noise measuring optical cable (2) to form a flat structure, and a protective outer sleeve (4) is arranged on the outer side of the flat structure to form the special distributed armored optical cable (100).

2. A special distributed armored cable for downhole long-term dynamic monitoring according to claim 1, wherein at least two first high temperature resistant single mode fibers (11) are arranged in the special high temperature resistant strain and vibration or noise measuring cable (1), a high temperature resistant composite material is injected or extruded into a cylindrical shape and tightly wrapped outside the first high temperature resistant single mode fibers (11) to form a strain and vibration or noise sensitive cable (12), a continuous stainless steel thin tube (13) is tightly wrapped outside the strain and vibration or noise sensitive cable (12), and a tail end of each first high temperature resistant single mode fiber (11) is knotted or provided with an extinction device (8) to prevent laser incident from the top end of the first high temperature resistant single mode fiber (11) from being reflected back to the top end of the fiber from the tail end.

3. A special distributed armored cable for downhole long-term dynamic monitoring according to claim 1, wherein the general high temperature and vibration or noise resistant measuring cable (2) is at least provided with more than two second high temperature resistant single-mode fibers (21), more than two high temperature resistant multimode fibers (22), the second high temperature resistant single-mode fibers (21) and the high temperature resistant multimode fibers (22) are tightly wrapped with an inner continuous stainless steel thin tube (23), the inner continuous stainless steel thin tube (23) is filled with high temperature resistant optical fiber paste, the outer wall of the inner continuous stainless steel thin tube (23) is tightly wrapped with an outer continuous stainless steel thin tube (24), wherein the tail ends of the two high temperature resistant multimode fibers (22) are welded together, the welded joint is fixed and protected by a U-shaped member, the tail ends of all the second high temperature resistant single-mode fibers (21) and the rest high temperature resistant multimode fibers (22) are respectively knotted or provided with an extinction device (8), laser light incident from the tip of the second high temperature resistant single mode optical fiber (21) and the tip of the high temperature resistant multimode optical fiber (22) is prevented from being reflected from the trailing end back to the fiber tip.

4. A special distributed armored cable for downhole long-term dynamic monitoring according to claim 1, wherein the pressure-bearing and wear-resistant reinforcing ribs (3) comprise a single or a plurality of steel wires, and the steel wires are high-strength stainless steel wires.

5. A downhole long term dynamic monitoring special distributed armored cable according to claim 1, wherein the protective outer jacket (4) is constructed of armored single or multiple layers of stainless steel wires.

6. A downhole long-term dynamic monitoring system, comprising the special distributed armored optical cable (100) of any one of claims 1 to 5, further comprising a metal casing (6), and a DSS/DAS/DTS composite modem instrument (5) placed near the wellhead, wherein the special distributed armored optical cable (100) is fixed outside the metal casing (6); the special distributed armored optical cable (100) is characterized in that one end containing the extinction device (8) is the lower end, and the upper end is connected with a DSS/DAS/DTS composite modulation and demodulation instrument (5).

7. A downhole long term dynamic monitoring system according to claim 6, wherein the DSS/DAS/DTS composite modem instrument (5) comprises data acquisition and modem functions of distributed fiber optic strain sensing, distributed fiber optic acoustic sensing and distributed fiber optic temperature sensing.

8. A monitoring method of a downhole long term dynamic monitoring system according to claim 6 or 7, comprising the steps of:

(a) synchronously and slowly putting the metal sleeve (6) and the special distributed armored optical cable (100) into a drilled well hole;

(b) an annular metal clip (7) is arranged at the junction of the two metal sleeves (6) at the wellhead to fix and protect the special distributed armored optical cable (100) from moving and rotating or being damaged in the process of descending the metal sleeves (6);

(c) after the metal casing (6) is completely put down, pumping cement slurry from the well bottom by using a high-pressure pump truck, returning the cement slurry to the well head from the well bottom along an annular area between the outer wall of the metal casing (6) and a drill hole, and permanently fixing the metal casing (6), the special distributed armored optical cable (100) and stratum rock together after the cement slurry is solidified;

(d) two first high-temperature-resistant single-mode optical fibers (11) in the special high-temperature-resistant strain and vibration or noise measurement optical cable (1) are respectively connected to a DSS signal input end and a DAS signal input end of a DSS/DAS/DTS composite modulation and demodulation instrument (5) at a wellhead;

(e) the top ends of two high-temperature-resistant multimode optical fibers (22) which are connected together at the tail ends in the universal high-temperature-resistant temperature and vibration or noise measurement optical cable (2) are respectively connected to the DTS double-end signal input end of a DSS/DAS/DTS composite modulation and demodulation instrument (5) at a well head;

(f) DSS signals and DAS signals continuously measured by a DSS/DAS/DTS composite modulation and demodulation instrument (5) are modulated and demodulated, and DSS data and DAS data are converted into strain data and vibration data or noise data generated when underground ground stress acts on a metal sleeve (6) and a special high-temperature-resistant strain and vibration or noise measurement optical cable (1);

(g) carrying out modulation and demodulation on DTS signals continuously measured by a DSS/DAS/DTS composite modulation and demodulation instrument (5), and converting DTS data into temperature change data generated on a temperature and vibration or noise measurement optical cable (2) along the underground general high temperature resistance;

(h) and according to the monitored and measured temperature data outside the downhole metal casing (6), using the formula:

Δλ/λ＝-Δυ/υ＝K_TΔt+K

wherein λ and υ are respectively the averageOptical wavelength and frequency; k_TAnd KTemperature and strain standard constants, respectively;

(i) for the DTS data which are input from the two ends and measured on the two high-temperature-resistant multimode optical fibers connected with the tail end, the formula can be applied to correct the drift of the spectrum of the scattered light in the optical fibers caused by the stress or strain change acted on the high-temperature-resistant multimode optical fibers (22) of the DTS data measured in the step (g) so as to obtain the real temperature change data of the outer wall of the metal sleeve (6) with the strain influence eliminated; the differential of the temperature change data of the outer wall of the metal sleeve (6) which is monitored and measured in real time for a long time to the time is obtained, and the temperature gradient of the temperature change data along with the time change is obtained;

correcting the DSS data measured in the step (f) for the drift of the spectrum of the scattered light in the optical fiber caused by the temperature change by using the temperature value of the specific measuring position, and obtaining the true strain value of the outer wall of the metal sleeve (6) with the temperature influence eliminated;

(j) calculating the differential of the strain quantity (step i) on the time, which is used for eliminating the influence of temperature change on the outer wall of the metal sleeve (6) monitored and measured in real time for a long time, so as to obtain the change rate of the strain quantity along with the time;

(k) analyzing the strain and the strain rate of the outer wall of the metal casing (6) monitored and measured in real time for a long time, and timely giving an early warning or an alarm when the strain and the strain rate of the metal casing (6) exceed a threshold value and a well section which is possibly deformed and damaged by the metal casing (6) is found according to a strain and strain rate threshold value standard of the metal casing (6) set by underground engineering;

(l) And (3) calculating the flow rate and the change of oil, gas and water of each oil and gas production well section in the well or the well fluid injection amount and the change of the well fluid of each water injection or steam injection or carbon dioxide injection or polymer injection well section in the well by using a multi-parameter comprehensive inversion method according to the noise signal and the temperature and the relation between the temperature gradient change and the oil, gas and water flow of the perforation section which are measured in the step (f) and the underground noise data and the temperature and temperature gradient data after strain influence is eliminated in the step (i), and acquiring the fluid production profile or the water absorption profile of each oil and gas production well and the water injection or steam injection or carbon dioxide injection or polymer injection displacement well in the well, thereby realizing the long-term dynamic monitoring of the change rule of the oil and gas production well or the fluid injection displacement well in the development and production process.

Technical Field

The invention belongs to the technical field of strain measurement, and particularly relates to a special distributed armored optical cable for underground long-term dynamic monitoring, a monitoring system and a monitoring method.

Background

The optical fiber sensing technology started in 1977 and developed rapidly along with the development of the optical fiber communication technology, and the optical fiber sensing technology is an important mark for measuring the informatization degree of a country. The optical fiber sensing technology is widely applied to the fields of military affairs, national defense, aerospace, industrial and mining enterprises, energy environmental protection, industrial control, medicine and health, metering test, building, household appliances and the like, and has a wide market. There are hundreds of fiber sensing technologies in the world, and physical quantities such as temperature, pressure, flow, displacement, vibration, rotation, bending, liquid level, speed, acceleration, sound field, current, voltage, magnetic field, radiation and the like realize sensing with different performances.

The downhole optical fiber sensing system can be used downhole to make measurements of stress, strain, pressure, temperature, noise, vibration, acoustic, seismic, flow, compositional analysis, electric and magnetic fields. The system is based on a full armored optical cable structure, and the sensor and the connecting and data transmission cable are all made of optical fibers. At present, there are various underground armored optical cables, such as those placed in an underground control pipeline, placed in a coiled tubing, directly integrated into the wall of the coiled tubing made of composite material, bound and fixed outside the coiled tubing, placed in a casing, bound and fixed outside the casing and permanently fixed with well-cementing cement.

The existing underground armored optical cable is generally characterized in that optical fibers are arranged in continuous slender metal tubes, optical fiber paste is injected, one or more layers of slender metal tubes are sleeved according to the well depth and the bottom pressure, one or more layers of armored steel wires are woven outside the slender metal tubes, the compression resistance, the tensile resistance and the impact resistance of the armored optical cable are improved, and the optical fibers in the innermost layer of slender metal tubes are protected from being damaged in the process of descending the well along with a sleeve. However, armored cables of this construction have at least two problems: (1) the single-mode and multi-mode optical fibers placed in the slender metal thin tube can only be coupled with the inner wall of the slender metal tube through non-solid optical fiber paste, and then are coupled with the outer wall of the metal sleeve and the stratum through the outer layer slender metal tube and the outermost layer armored steel wire, so that the optical fibers in the armored optical cable cannot well couple and induce the stratum stress to concentrate on the rock stratum or the metal sleeve strain (deformation) produced at a local well section, and cannot well inductively couple seismic waves or noise signals transmitted from a seismic source to the underground; (2) although the optical fiber in the armored optical cable is protected by one or more layers of the elongated metal tubes and the outermost layer of the armored steel wire, in the process of descending the optical cable along with the metal casing, the underground pressure, the friction force and the huge impact force finally directly act on the outer wall of the elongated metal tube on the innermost layer, the hollow elongated metal tube can be extruded, deformed and even broken by the underground huge pressure and the huge impact force during the operation of descending the casing, and the optical fiber at the well section of the damaged armored optical cable is extruded by external force and even broken.

Disclosure of Invention

The invention provides a special distributed armored optical cable for underground long-term dynamic monitoring, a monitoring system and a monitoring method, wherein when the special distributed armored optical cable is bound at the outer side of a sleeve of a vertical well, an inclined well or a horizontal well by using a metal clamp and is permanently fixed by using well cementation cement, a distributed optical fiber strain sensor (DSS), a distributed optical fiber acoustic wave sensor (DAS) and a distributed optical fiber temperature sensor (DTS) composite modulation demodulation instrument (DSS/DAS/DTS) on the ground of a wellhead are connected with the special armored optical cable near the wellhead, and then an underground long-term real-time dynamic comprehensive monitoring system based on distributed optical fiber sensing is formed.

The invention aims to overcome the defects that the existing underground armored optical cable has insufficient sensitivity to strain and vibration or noise, is not well coupled and is easy to wear, extrude and damage in the process of going down a well along with a metal sleeve, and provides a method for packaging a special high-temperature-resistant strain and vibration or noise measuring optical cable, a general high-temperature-resistant temperature and vibration or noise measuring optical cable and a pressure-bearing wear-resistant reinforcing rib consisting of three groups of single or multiple steel wires in a special distributed armored optical cable respectively, wherein the outer side of the special distributed armored optical cable forms a protective outer sleeve by using armored single-layer or multiple-layer stainless steel wires to form a circular. Then binding the special armored optical cable with a circular flat structure at the outer side of the casing of the vertical well, the inclined well or the horizontal well and permanently fixing the special armored optical cable with the casing of the circular flat structure by using well cementation cement to construct a long-term real-time monitoring and measuring system based on the distributed optical fiber sensing for underground stratum strain distribution change, monitoring and measuring the damage or damage possibly caused by underground stress to the underground casing and various underground tools and pipelines in a long-term real-time manner, and providing an indispensable means, system and method for ensuring the long-term stable, safe and reliable work of an oil and gas production well, a water injection well and a monitoring or observation well.

In order to achieve the purpose, the specific technical scheme of the invention is as follows:

the special distributed armored optical cable for underground long-term dynamic monitoring comprises a special high-temperature-resistant strain and vibration or noise measuring optical cable, a general high-temperature-resistant temperature and vibration or noise measuring optical cable and three groups of pressure-bearing anti-wear reinforcing ribs, wherein the five groups of pressure-bearing anti-wear reinforcing ribs form a flat structure, the two sides of the special strain and vibration or noise measuring optical cable and the two sides of the general temperature and vibration or noise measuring optical cable are protected by the pressure-bearing anti-wear reinforcing ribs, and a protective jacket formed by armored steel wires is arranged on the outer side of the flat structure formed by the five.

The special high-temperature-resistant strain and vibration or noise measurement optical cable is internally provided with at least more than two first high-temperature-resistant single-mode optical fibers, a high-temperature-resistant composite material is extruded into a cylindrical shape through injection molding or comprises the first high-temperature-resistant single-mode optical fibers to form a strain and vibration or noise sensitive optical cable, the strain and vibration or noise sensitive optical cable is tightly wrapped by a continuous stainless steel thin tube, all the first high-temperature-resistant single-mode optical fibers are knotted at the tail ends or are provided with an extinction device, and laser incident from the top ends of the first high-temperature-resistant single-mode optical fibers is prevented from being reflected back to the top.

The general high-temperature-resistant temperature and vibration or noise measurement optical cable comprises an inner continuous stainless steel thin tube, at least more than two second high-temperature-resistant single-mode optical fibers are arranged in the inner continuous stainless steel thin tube, more than two high-temperature-resistant multimode optical fibers are filled in the inner continuous stainless steel thin tube, an outer continuous stainless steel thin tube is arranged outside the inner continuous stainless steel thin tube, the tail ends of the two high-temperature-resistant multimode optical fibers are welded together, the high-temperature-resistant multimode optical fibers at the welding position are fixed and protected by a U-shaped piece, and a knot is tied or an extinction device is installed at the tail ends of all the second high-temperature-resistant single-mode optical fibers and other high-temperature-resistant multimode optical fibers to prevent laser incident from the top ends of the second high-temperature-resistant single-mode optical fibers and the top ends of the high.

The pressure-bearing anti-wear reinforcing ribs comprise three groups of single or multiple steel wires, and high-strength stainless steel wires are arranged on two sides of the special high-temperature-resistant strain and vibration or noise measurement optical cable and the general high-temperature-resistant temperature and vibration or noise measurement optical cable respectively.

The protective outer sleeve is formed by armored single-layer or multi-layer stainless steel wires.

The special distributed armored optical cable with the circular flat structure for the underground long-term dynamic monitoring is convenient to fix on the outer side of the metal sleeve and to go down along with the metal sleeve, the circular flat structure does not enable the special distributed armored optical cable for the underground long-term dynamic monitoring to rotate in the process of going down along with the sleeve, and pressure-bearing anti-wear reinforcing ribs made of stainless steel wires and arranged on two sides of the special high-temperature-resistant strain and vibration or noise measuring optical cable and the universal high-temperature-resistant temperature and vibration or noise measuring optical cable and armored single-layer or multi-layer stainless steel wires outside the circular flat structure can protect the special distributed armored optical cable from being worn or damaged by impact in the process of going down along with the sleeve.

The invention provides a long-term dynamic monitoring system in a well, which comprises the special distributed armored optical cable, a metal sleeve and a DSS/DAS/DTS composite modulation and demodulation instrument, wherein the DSS/DAS/DTS composite modulation and demodulation instrument is arranged near a well mouth; the special distributed armored optical cable comprises an extinction device, wherein one end of the extinction device is the lower end, and the upper end of the extinction device is connected with a DSS/DAS/DTS composite modulation and demodulation instrument.

The DSS/DAS/DTS composite modulation and demodulation instrument comprises data acquisition and modulation and demodulation functions of distributed optical fiber strain sensing, distributed optical fiber acoustic wave sensing and distributed optical fiber temperature sensing.

The monitoring method of the underground long-term dynamic monitoring system comprises the following steps:

(1) synchronously and slowly putting the metal sleeve and the special distributed armored optical cable into a drilled well hole;

(2) an annular metal clip is arranged at the junction of the two metal sleeves at the wellhead to fix and protect the special distributed armored optical cable from moving and rotating or being damaged in the process of casing running;

(3) pumping cement slurry from the well bottom by using a high-pressure pump truck after the metal casing is laid, returning the cement slurry to the well head from the well bottom along an annular area between the outer wall of the metal casing and the drill hole, and permanently fixing the metal casing, the special distributed armored optical cable and the stratum rock together after the cement slurry is solidified;

(4) two first high-temperature-resistant single-mode optical fibers in the special high-temperature-resistant strain and vibration or noise measuring optical cable are respectively connected to a DSS signal input end and a DAS signal input end of a DSS/DAS/DTS composite modulation and demodulation instrument at a wellhead;

(5) the top ends of two high-temperature-resistant multimode optical fibers which are connected together at the tail ends in the universal high-temperature-resistant temperature and vibration or noise measuring optical cables are respectively connected to the DTS double-end signal input end of the DSS/DAS/DTS composite modulation and demodulation instrument at a wellhead;

(6) the DSS signal and the DAS signal which are continuously measured by the DSS/DAS/DTS composite modulation and demodulation instrument are modulated and demodulated, and DSS data and DAS data are converted into strain data and vibration data or noise data which are generated by underground ground stress acting on a metal sleeve and a special high-temperature-resistant strain and vibration or noise measuring optical cable;

(7) carrying out modulation and demodulation on DTS signals continuously measured by the DSS/DAS/DTS composite modulation and demodulation instrument, and converting DTS data into temperature change data generated on a downhole general high-temperature-resistant temperature and vibration or noise measuring optical cable;

(8) according to the monitored and measured temperature data outside the underground metal casing, the formula is utilized:

Δλ/λ＝-Δυ/υ＝K_TΔt+K

wherein λ and υ are average light wavelength and frequency respectively; k_TAnd KTemperature and strain standard constants, respectively;

(9) for the DTS data which are input from the two ends and measured on the two high-temperature-resistant multimode optical fibers connected with the tail end, the formula can be applied, and the DTS data measured in the step (7) are corrected for the drift of the spectrum of the scattered light in the optical fibers caused by the change of the stress (strain) acting on the high-temperature-resistant multimode optical fibers, so that the true temperature change data of the outer wall of the metal sleeve, which eliminates the strain influence, can be obtained; the differential of the temperature change data of the outer wall of the metal sleeve on the time is obtained from the temperature change data monitored and measured in real time for a long time, and the temperature gradient of the temperature change data along with the change of the time is obtained;

correcting the DSS data measured in the step (6) by using the temperature value of the specific measurement position according to the drift of the spectrum of the scattered light in the optical fiber caused by the temperature change, and obtaining a true strain value of the outer wall of the metal sleeve, wherein the temperature influence is eliminated;

(10) calculating the differential of the strain quantity on the time, which is monitored and measured in real time for a long time and eliminates the temperature influence on the outer wall of the metal sleeve, so as to obtain the change rate of the strain quantity along with the time; (11) analyzing the strain and the strain rate of the outer wall of the metal casing which are monitored and measured in real time for a long time, and timely giving an early warning or an alarm when the strain and the strain rate of the metal casing exceed a threshold value and possibly cause the deformation and the damage of the metal casing according to the strain and strain rate threshold value standard of the metal casing set by underground engineering;

(12) and (6) utilizing the monitored and measured underground noise data (step 6), eliminating the temperature and temperature gradient data affected by strain (step 9), utilizing a multi-parameter comprehensive inversion method to calculate the flow and the change of oil, gas and water of each underground oil and gas production well section or the well fluid injection amount and the change of each underground water injection or steam injection or carbon dioxide injection or polymer injection well section according to the relation between the noise signal and the temperature and temperature gradient change measured by the underground perforation section and the oil, gas and water flow of the perforation section, and obtaining the production fluid section or water absorption section of each oil and gas production well and the water injection or steam injection or carbon dioxide injection or polymer injection well, thereby realizing the long-term dynamic monitoring of the change rule of the oil and gas production well or the liquid injection displacement well in the development and production process.

Drawings

FIG. 1 is a schematic cross-sectional structural view of a specialty distributed armored fiber optic cable of the present invention;

FIG. 2 is a schematic diagram of a downhole long term dynamic monitoring system of the present invention.

Detailed Description

The embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are not intended to limit the present invention, but are merely exemplary, and the advantages of the present invention will be more clearly understood and appreciated by way of illustration.

The invention relates to a special distributed armored optical cable for underground long-term dynamic monitoring and a corresponding monitoring method, and the specific implementation mode is as follows:

as shown in fig. 1, the underground long-term dynamic monitoring special distributed armored optical cable includes a special high-temperature-resistant strain and vibration or noise measuring optical cable 1, a general high-temperature-resistant temperature and vibration or noise measuring optical cable 2, pressure-bearing wear-resistant reinforcing ribs 3 formed by three groups of single or multiple high-strength stainless steel wires, the five groups of high-temperature-resistant strain and vibration or noise measuring optical cables form a flat structure, the two sides of the special strain and vibration or noise measuring optical cable 1 and the general temperature and vibration or noise measuring optical cable 2 are protected by the pressure-bearing wear-resistant reinforcing ribs 3, and a protective outer sleeve 4 formed by armored steel wires is arranged outside the flat structure to form the special distributed armored optical.

The special high-temperature-resistant strain and vibration or noise measurement optical cable 1 is internally provided with at least more than two first high-temperature-resistant single-mode optical fibers 11, a high-temperature-resistant composite material is molded or extruded into a cylinder shape and comprises the first high-temperature-resistant single-mode optical fibers 11 to form a strain and vibration or noise sensitive optical cable 12, the outer wall of the strain and vibration or noise sensitive optical cable 12 is tightly wrapped on a continuous stainless steel thin tube 13, the tail ends of all the first high-temperature-resistant single-mode optical fibers 11 are knotted or provided with an extinction device 8, and laser incident from the top end of the first high-temperature-resistant single-mode optical fibers 11 is prevented from being reflected.

The general high-temperature-resistant temperature and vibration or noise measurement optical cable 2 comprises a continuous inner stainless steel tubule 23, at least more than two second high-temperature-resistant single-mode optical fibers 21 and more than two high-temperature-resistant multimode optical fibers 22 are arranged in the inner continuous stainless steel tubule 23, high-temperature-resistant optical fiber paste is filled in the inner continuous stainless steel tubule 23, an outer continuous stainless steel tubule 24 is tightly sleeved outside the inner continuous stainless steel tubule 23, the tail ends of the two high-temperature-resistant multimode optical fibers 22 are welded together, the high-temperature-resistant multimode optical fibers 22 at the welding position are fixed and protected by a U-shaped piece, the tail ends of all the second high-temperature-resistant single-mode optical fibers 21 and other high-temperature-resistant multimode optical fibers 22 are knotted or provided with an extinction device 8, and laser incident from the top ends of the second high-temperature-resistant single-mode optical fibers.

The pressure-bearing anti-wear reinforcing ribs 3 are made of high-strength stainless steel wires and are respectively arranged on two sides of the special high-temperature-resistant strain and vibration or noise measuring optical cable 1 and the general high-temperature-resistant temperature and vibration or noise measuring optical cable 2.

The protective outer jacket 4 is formed of armored single-layer or multi-layer stainless steel wires.

As shown in fig. 2, the downhole long-term dynamic monitoring system includes the special distributed armored optical cable 100, a metal casing 6, and a DSS/DAS/DTS composite modem 5 placed near a wellhead, wherein the special distributed armored optical cable 100 is fixed outside the metal casing 6; the special distributed armored optical cable 100 has a extinction device 8 at one end as a lower end and a DSS/DAS/DTS composite modulation and demodulation instrument 5 at the upper end.

The DSS/DAS/DTS composite modulation and demodulation instrument 5 comprises data acquisition and modulation and demodulation functions of distributed optical fiber strain sensing, distributed optical fiber acoustic wave sensing and distributed optical fiber temperature sensing.

The monitoring method of the underground long-term dynamic monitoring system comprises the following steps:

(a) synchronously and slowly putting the metal sleeve 6 and the special distributed armored optical cable 100 into a drilled well hole;

(b) an annular metal clip 7 is arranged at the junction of the two metal sleeves 6 at the wellhead to fix and protect the special distributed armored optical cable 100 from moving and rotating or being damaged in the process of descending the metal sleeves 6;

(c) after the metal casing 6 is put down, pumping cement slurry from the well bottom by using a high-pressure pump truck, returning the cement slurry to the well head from the well bottom along an annular area between the outer wall of the metal casing 6 and the drill hole, and permanently fixing the metal casing 6, the special distributed armored optical cable 100 and the stratum rock together after the cement slurry is solidified;

(d) two first high-temperature-resistant single-mode optical fibers 11 in the special high-temperature-resistant strain and vibration or noise measurement optical cable 1 are respectively connected to a DSS signal input end and a DAS signal input end of a DSS/DAS/DTS composite modulation and demodulation instrument at a wellhead;

(e) the top ends of two high-temperature-resistant multimode optical fibers 22 which are connected together at the tail ends in the universal high-temperature-resistant temperature and vibration or noise measurement optical cable 2 are respectively connected to the DTS double-end signal input end of the DSS/DAS/DTS composite modulation and demodulation instrument at a well head;

(f) DSS signals and DAS signals continuously measured by a DSS/DAS/DTS composite modulation and demodulation instrument are modulated and demodulated, and DSS data and DAS data are converted into strain data and vibration data or noise data which are generated when underground ground stress acts on the metal sleeve 6 and the special high-temperature-resistant strain and vibration or noise measuring optical cable 1;

(g) carrying out modulation and demodulation on DTS signals continuously measured by the DSS/DAS/DTS composite modulation and demodulation instrument, and converting DTS data into temperature change data generated on the underground general high-temperature-resistant temperature and vibration or noise measuring optical cable 2;

(h) and according to the monitored and measured temperature data outside the downhole metal casing 6, utilizing the formula:

Δλ/λ＝-Δυ/υ＝K_TΔt+K

wherein λ and υ are average light wavelength and frequency respectively; k_TAnd KTemperature and strain standard constants, respectively;

(i) for the DTS data which are input from the two ends and measured on the two high-temperature-resistant multimode optical fibers connected with the tail end, the formula can be applied to correct the drift of the spectrum of the scattered light in the optical fibers caused by the change of the stress (strain) acting on the high-temperature-resistant multimode optical fibers 22 of the DTS data measured in the step (g) so as to obtain the real temperature change data of the outer wall of the metal sleeve 6 without the influence of the strain; the differential of the temperature change data of the outer wall of the metal sleeve 6, which is monitored and measured in real time for a long time, to the time is obtained, and the temperature gradient of the temperature change data along with the change of the time is obtained;

correcting the DSS data measured in the step (f) for the drift of the spectrum of the scattered light in the optical fiber caused by the temperature change by using the temperature value of the specific measurement position, and obtaining a true strain value of the outer wall of the metal sleeve 6, wherein the temperature influence is eliminated;

(j) calculating the differential of the strain quantity on the outer wall of the metal sleeve 6, which is monitored and measured in real time for a long time and eliminates the temperature influence, to the time, and obtaining the change rate of the strain quantity along with the time;

(k) analyzing the strain and the strain rate of the outer wall of the metal sleeve 6 monitored and measured in real time for a long time, and timely giving an early warning or an alarm when the strain and the strain rate of the metal sleeve 6 exceed a threshold value and a well section which is possibly deformed and damaged by the metal sleeve 6 is found according to a strain and strain rate threshold value standard of the metal sleeve 6 set by underground engineering;

(l) And (f) utilizing the monitored and measured downhole noise data (step f), eliminating temperature and temperature gradient data (step i) of strain influence, calculating the flow and the change of oil, gas and water of each downhole oil and gas production well section by utilizing a multi-parameter comprehensive inversion method according to the relationship between the noise signal and the temperature and temperature gradient change measured by the downhole perforation section and the oil, gas and water flow of the perforation section, or the well fluid injection amount and the change of each downhole water injection or steam injection or carbon dioxide injection or polymer injection well section, and obtaining the production fluid profile or water absorption profile of each oil and gas production well and the water injection or steam injection or carbon dioxide injection or polymer injection well, thereby realizing the long-term dynamic monitoring of the change rule of the oil and gas production well or the liquid injection displacement well in the development and production process.