WO2022143428A1 - Safe operation monitoring system and monitoring method for underground gas storage - Google Patents

Abstract

A safe operation monitoring system and monitoring method for an underground gas storage. The system comprises armored optical cables (6, 7) and quasi-distributed optical fiber pressure sensors (9, 10), which are arranged on the inside and outside of casing pipes (4) of all gas injection wells (1), gas recovery wells (2) and monitoring wells (3) and on the outside of in-well gas injection and recovery pipes (5); underground three-component detector arrays (8), which are arranged in some of the monitoring wells (3); and composite modulation and demodulation instruments (11), which are placed in the vicinity of wellheads. According to the monitoring method, by comprehensively using all underground noise, temperature, pressure and stress/strain changes and distribution features of microseismic events that are monitored in real time online, intelligent comprehensive analysis and evaluation are performed on all parameters and information that are monitored in real time online, various risks or accidents affecting the safe and stable operation of a gas storage are graded and classified, and early warning signals and information of accident risks are released in a timely manner, so as to ensure the long-term stable and safe operation of the gas storage.

Description

Safety operation monitoring system and monitoring method of underground gas storage technical field

The invention belongs to the technical field of well logging, and in particular relates to a safety operation monitoring system and a monitoring method of an underground gas storage.

Background technique

Underground gas storage is a geological structure and supporting facilities for storing natural gas. The main functions are gas peak regulation and safe gas supply, strategic reserve, improving the utilization factor of pipelines to save investment, and reducing gas transmission costs. The urban gas market demand fluctuates greatly with seasons and day and night. It is difficult to solve the contradiction of large fluctuations in gas consumption only by relying on the balanced gas transmission of the gas transmission network system to adjust the flow in a small range. The underground gas storage is used to store the surplus gas in the gas transmission system when the gas consumption is low, and it is produced during the peak gas consumption to supplement the insufficient gas supply in the pipeline to solve the problem of gas peak regulation. When the gas source is interrupted and the gas transmission system stops, the underground gas storage can be used as the gas source to ensure continuous gas supply, which plays the dual role of peak regulation and safe gas supply. The depth of underground gas storage generally ranges from 250 to 2000 m, and the depth of most aquifer gas storage and depleted gas storage gas storage in the world does not exceed 1000 m. The process and technical parameters of gas injection, gas recovery and pressurization of the underground gas storage are determined according to the requirements of the specific project. The main components of the underground gas storage include underground gas storage layers, injection and production wells, surface natural gas processing, pressurization, transmission and distribution, metering, automatic control and other major engineering facilities connected to the gas transmission trunk line, and auxiliary facilities such as water supply, power supply, and communication.

According to different purposes, underground UGSs are usually divided into four types: gas source UGSs, base UGSs, peak-shaving UGSs and storage UGSs. According to the different geological structures of UGS construction, it is usually divided into four categories: depleted oil and gas reservoir UGS, aquifer UGS, salt cavern UGS and abandoned mine cavern UGS.

Gas source gas storage: It is located near the gas source or the first station of the gas transmission trunk line and is used to adjust the gas supply capacity of the gas source. Due to the distance from the natural gas consumption center, the technical and economic indicators are unreasonable, and the number of its practical applications is small.

Base-type gas storage: It is located near the gas market and is mainly used to adjust and alleviate the seasonal unevenness of natural gas demand in large natural gas consumption centers. Generally, it is a depleted oil and gas reservoir gas storage and aquifer gas storage, with a large gas storage capacity and a working gas volume of 50 to 100 days of peak daily gas production.

Peak-shaving gas storage: A market gas storage that provides peak gas shaving during day, night, hour, and short-term emergency gas supply during gas transmission system accidents. Generally, it is a salt cavern or a waste mine-cavern gas storage (there are also depleted gas storage gas storages), with high gas production rate and relatively small capacity, and the working gas volume is the peak daily gas production volume of 10 to 30 days.

Storage type gas storage depots: market gas storage depots used as strategic reserves and backup gas sources, mostly needed by countries that mainly rely on imported natural gas.

Gas storage in depleted oil and gas reservoirs: underground gas storages built in depleted oil and gas fields. Most are built in depleted gas reservoirs, and a few are built in depleted oil reservoirs containing associated gas. When the gas recovery degree of the depleted gas reservoir reaches 70%, it is most suitable for the gas storage. There is a small amount of oil and gas remaining in this gas storage, and its operation is relatively simple; some of the original gas (oil) wells and process equipment can be used after inspection and maintenance. Only some new facilities need to be built, the investment is small, and the application is the most common. .

Aquifer gas storage: A gas storage built in an aquifer. The principle of gas storage is to inject gas into the water-bearing formation, and squeeze the water in the pore space of the rock down to the edge of the structure to store gas. The gas storage is generally structurally complete, and drilling and completion can be completed at one time; however, the gas-water interface is difficult to control and the cost is high. In areas where there are no depleted oil and gas fields, aquifers may be used to build gas storage.

Salt cavern gas storage: An underground gas storage built in salt domes or salt rocks. High-pressure natural gas is usually stored in cavities created by underground salt mines using a salt-dissolving process. The salt-dissolving process involves the circulation and discharge of a large amount of water, resulting in high construction investment and operating costs of the salt-cavern gas storage.

Abandoned Mine Gas Storage: A gas storage built in an abandoned mine cave. The original wellbore is difficult to strictly seal, and there is a danger of gas leakage to the ground; a certain amount of coalbed methane still exists in the coal mine, which reduces the calorific value of the produced gas in the warehouse.

Optical fiber sensing technology started in 1977 and developed rapidly with the development of optical fiber communication technology. Optical fiber sensing technology is an important symbol for measuring the degree of informatization of a country. Optical fiber sensing technology has been widely used in military, national defense, aerospace, industrial and mining enterprises, energy and environmental protection, industrial control, medicine and health, measurement and testing, construction, household appliances and other fields, and has a broad market. There are hundreds of optical fiber sensing technologies in the world, such as temperature, pressure, flow, displacement, vibration, rotation, bending, liquid level, speed, acceleration, sound field, current, voltage, magnetic field and radiation and other physical quantities have achieved different performance. sensing.

Downhole fiber optic sensing systems can be used downhole for pressure, temperature, noise, vibration, acoustic, seismic, flow, composition analysis, electric and magnetic field measurements. The system is based on a fully armored fiber optic cable structure, with sensors and connection and data transmission cables made of fiber optic cables. At present, there are a variety of laying methods for downhole armored optical cables, such as placing in the downhole control pipeline, putting into the coiled tubing, directly integrating into the coiled tubing wall made of composite materials, bundling and fixing the outside of the coiled tubing, and placing them in the casing. Layout methods such as inside the pipe and bundling on the outside of the casing and permanently fixed with cement.

The distributed temperature (DTS) measurement of the whole well section by laying inside and outside the casing or bundling the armored optical cable outside the coiled tubing has been widely used in the development of oil and gas resources. We can calculate the well fluid (oil and gas) output or water injection according to the temperature change measured in the downhole oil and gas production section (perforation section) or the temperature change measured in the injection section (perforation section) of the water injection gas injection well Gas injection volume. However, due to the limited spatial resolution and temperature measurement sensitivity of ordinary DTS modulation and demodulation instruments, there is a certain error in the well temperature change and the exact position measured by the DTS method, resulting in the well temperature in the perforated section calculated only based on the well temperature change. The liquid (oil and gas) output or water injection and gas injection have a large error, and it is impossible to accurately calculate the oil, gas and water produced in the perforation section only based on the change of well temperature.

The distributed acoustic sensing (DAS) measurement of the whole well section by laying inside and outside the casing or bundling the armored optical cable outside the coiled tubing has been widely used in the development of oil and gas resources, but at present, DAS-VSP data acquisition, Microseismic monitoring and passive seismic data acquisition are the main focus. The industry has just begun to use DAS technology to collect downhole noise data, and use the noise data to predict the production of oil, gas and water in the downhole perforation section. Only relying on downhole noise data to infer the production of oil, gas and water in the downhole perforated well section is basically a qualitative or semi-quantitative interpretation, and the error is relatively large.

In the long-term high-pressure gas injection and gas production cycle peak-shaving operation of the gas storage, the cementing cement sheath outside the gas injection well or gas production well casing will gradually become loose and damaged in the cyclic change of high and low pressure, resulting in underground high-pressure natural gas. Potential safety risks and accidents of leakage to the surface along the annulus between the outer wall of the casing of the gas injection or production well and the borehole. In addition, when high-pressure natural gas is injected into the ground through gas injection wells, it may induce activation of underground faults. If there are large and small faults activated by high-pressure natural gas on the sealing caprock of the gas storage, the activated faults may destroy the integrity of the sealing caprock of the gas storage, causing underground high-pressure natural gas to be activated along the sealing caprock. A major safety hazard or accident that leaks from a fault to the ground. Therefore, the underground gas storage is in urgent need of a real-time online monitoring system for the hidden dangers and accidents of high-pressure natural gas leakage, which can ensure its long-term safe and stable operation.

SUMMARY OF THE INVENTION

In order to enable the underground gas storage to operate safely and stably for a long time, there will be no leakage of underground high-pressure natural gas to the ground along the annulus between the outer wall of the casing of the gas injection well or the gas production well or the monitoring well and the stratum, or along the annulus area activated by the underground high-pressure natural gas. The rupture zone of the fault located in the upper sealing caprock of the gas storage leaks to the ground, and the gas storage needs a system for long-term real-time monitoring of hidden dangers and accidents of underground high-pressure natural gas leakage.

The long-term monitoring system for the safe operation of the underground gas storage includes gas injection wells, gas production wells, monitoring wells, and metal casings. The metal casings have built-in gas injection and production pipes, and the first measurement armored optical cable is fixed on the outside of the metal casings. The gas injection and production pipes in the wells A second measurement armored optical cable is fixed on the outside; the monitoring well is provided with a second measurement armored optical cable with permanent magnet adsorption or electromagnetic induction adsorption, or an underground three-component detector array;

A plurality of first downhole quasi-distributed optical fiber pressure sensors are fixed on the outside of the metal casing, and a plurality of second downhole quasi-distributed optical fiber pressure sensors are fixed on the outside of the gas injection and production pipe in the well;

Also includes composite modulation and demodulation instruments placed near the wellhead;

The composite modulation and demodulation instruments include distributed acoustic wave sensing DAS, distributed temperature sensing DTS, distributed optical fiber strain/stress sensing DSS and quasi-distributed optical fiber pressure sensing DPS; A measurement armored optical cable is connected with a second measurement armored optical cable.

The first measurement armored optical cable and the second measurement armored optical cable are both multi-parameter armored optical cables.

Specifically, there are at least two or more single-mode optical fibers with high temperature resistance in the first measurement armored optical cable. Strain or vibration/noise sensitive optical cable, the sensitive optical cable is tightly wrapped with a continuous stainless steel tube, and a knot or a light extinction device is installed at the end of each single-mode fiber to prevent the laser incident from the top of the single-mode fiber from being reflected from the end. back to the top of the fiber.

There are at least two or more single-mode optical fibers and more than two multi-mode optical fibers in the second measurement armored optical cable, and the single-mode optical fibers and the multi-mode optical fibers are tightly wrapped with inner continuous stainless steel thin tubes, and the inner continuous stainless steel thin tubes are filled inside. High temperature resistant optical fiber paste, the outer wall of the inner continuous stainless steel thin tube is tightly sleeved with the outer continuous stainless steel thin tube, in which the tail ends of the two multimode optical fibers are fused together, and the fusion joint is fixed and protected by a U-shaped piece. Knot or install a light-extinguishing device at the tail end of the remaining multimode fiber to prevent the laser light incident from the tip of the single mode fiber and the tip of the multimode fiber from being reflected back to the tip of the fiber from the tail end.

Wherein, the first downhole quasi-distributed pressure sensor and the second downhole quasi-distributed pressure sensor are Faber cavity optical fiber pressure sensors, or grating pressure sensors, or piezoelectric crystal pressure sensors;

A plurality of first downhole quasi-distributed pressure sensors are sequentially connected in series through the first measurement armored optical cable at equal intervals;

A plurality of second downhole quasi-distributed pressure sensors are sequentially connected in series through the second measurement armored optical cable at equal intervals.

Further, a first annular metal clip is also included, and the first annular metal clip is installed and fixed at the metal casing shoe.

It also includes a second annular metal clip, which is installed and fixed on the outside of the gas injection and production pipe in the well at equal intervals.

Preferably, the three-component detector array is one of a three-component electromagnetic detector, a three-component piezoelectric detector, a three-component acceleration detector, a three-component MEMS detector, and a three-component fiber optic detector.

The monitoring method of the above-mentioned underground gas storage safety operation monitoring system includes the following steps:

(a) In newly drilled gas injection wells, gas production wells and some monitoring wells, run the metal casing and the first measurement armored optical cable into the drilled wellbore slowly and synchronously;

(b), at the wellhead, install the first annular metal clip at the junction of the two metal sleeves to fix and protect the first measurement armored optical cable from being rotated and/or damaged during the process of running the sleeve;

(c) Use a high-pressure pump truck to pump cement slurry to the bottom of the gas injection well, gas production well and monitoring well, so that the cement slurry is returned to the wellhead from the bottom of the well along the annulus between the outer wall of the metal casing and the borehole, and the cement slurry After consolidation, the metal sleeve, the first measurement armored optical cable and the formation rock are permanently fixed together;

(d), run the gas injection and production pipe and the second measurement armored optical cable into the metal casing well after cementing and completion synchronously and slowly;

(e), at the wellhead, install the second annular metal clip on the gas injection and production pipe according to the same spacing, fix and protect the second measurement armored optical cable from being damaged during the installation of the gas injection and production pipe in the downhole and make the first 2. There is good acoustic signal coupling between the armored optical cable and the coiled tubing;

(f), at the wellhead, connect the single-mode optical fiber or sensitive optical cable in the first measurement armored optical cable to the DAS signal input end of the composite modulation and demodulation instrument, and connect the single multimode optical fiber or the single multimode optical fiber in the first measurement armored optical cable or The two multimode fibers with U-shaped splices at the ends are connected to the DTS signal input end (single-end input or double-end input) of the composite modem instrument;

(g) Connect the single-mode optical fiber or sensitive optical cable in the second measurement armored optical cable to the DAS signal input end of the composite modulation and demodulation instrument at the wellhead, and connect the single multimode optical fiber or the single multimode optical fiber in the second measurement armored optical cable or The two multimode fibers with U-shaped splices at the ends are connected to the DTS signal input end (single-end input or double-end input) of the composite modem instrument;

(h), connect the sensitive optical cable in the first measurement armored optical cable to the DSS signal input end of the composite modulation and demodulation instrument at the wellhead;

(i), at the wellhead, connect the optical fibers of the first armored photoelectric composite cable and the second armored photoelectric composite cable to the first downhole quasi-distributed optical fiber pressure sensor and the second downhole quasi-distributed optical fiber pressure sensor, respectively, to the composite cable. DPS signal input terminal of modem instrument;

(j) In some monitoring wells at the depth close to the gas storage layer, place the downhole three-component geophone array, and push each stage of the three-component geophone on the downhole three-component geophone array tightly against the inner wall of the metal casing Or go up the wall of the well, and connect the armored optoelectronic composite cable connecting the three-component detector array downhole to the DAS signal input end of the composite modulation and demodulation instrument near the wellhead;

(k) During the normal production operation of the gas storage, that is, gas injection or gas production, the composite modulation and demodulation instrument placed next to the wellhead shall continuously monitor and measure the first measurement armored optical cable outside the metal casing and the first measurement outside the gas injection and production pipe in the well. 2. Measure the DAS and DTS signals in the armored optical cable, and continuously monitor and measure the pressure signals of the first downhole quasi-distributed pressure sensor and the second downhole quasi-distributed pressure sensor connected in series outside the metal casing and the outside of the gas injection and production pipe in the well;

(l) During the normal production operation of the gas storage, that is, during gas injection or gas production, the DSS signal output from the sensitive optical cable in the first measurement armored optical cable outside the metal casing is continuously monitored and measured by the composite modulation and demodulation instrument placed next to the wellhead. ,

(m), modulate and demodulate the DAS signal, DTS signal, DSS signal and DPS signal continuously measured by the composite modulation and demodulation instrument, and convert the DAS data, DTS data, DSS data and DPS data into the whole section of all monitoring wells Distribution data of noise intensity, temperature, stress/strain and pressure at each pressure sensor location;

(n), modulate and demodulate the DAS signals of all monitoring wells continuously measured by the composite modulation and demodulation instrument, convert the DAS data into the underground microseismic data recorded by the monitoring wells, and process the three-component detector arrays in some monitoring wells in real time recorded microseismic data;

(o) According to the monitored and measured downhole noise, temperature and pressure data of gas injection wells and gas production wells, use multi-parameter comprehensive inversion method to calculate the gas flow and its changes in each gas injection well section and gas production well section downhole, So as to realize the long-term real-time dynamic monitoring of the production process of gas injection and gas recovery of the gas storage and the changes of the injection and production volume;

(p) According to the monitoring and measurement of the underground stress (strain) data of the entire well section of the gas injection well, gas production well and the casing outside the monitoring well, real-time online analysis finds the parts or well sections where casing damage may occur, and timely takes the casing damage parts measures to prevent major safety hazards or accidents in which the underground high-pressure natural gas of the gas storage leaks to the ground along the casing damage of gas injection wells, gas production wells or monitoring wells;

(q), according to the first measurement armored optical cable or the second measurement armored optical cable in the gas injection well, the gas production well and the monitoring well, or the three-component geophone array in the well to monitor and record the energy magnitude of the underground microseismic events in real time and the time The change of the spatial distribution law, online real-time judgment whether the normal gas injection and gas production operations of the gas storage have induced and activated underground large and small faults, whether there are small faults induced and activated by high-pressure natural gas on the sealing caprock of the gas storage, and the activated gas Whether the small fault will damage the integrity of the gas storage seal caprock, and whether there will be a major safety hazard or accident that the underground high-pressure natural gas leaks to the ground along the activated small fault on the seal caprock;

(r) Comprehensively make full use of the first measurement armored optical cable, the second measurement armored optical cable and some of the downhole three installed in the monitoring well, which are arranged inside and outside the casing of all the gas injection wells, gas production wells and monitoring wells and the gas injection and production pipes in the well. Component detector array, real-time online monitoring of all downhole noise, temperature, pressure, stress/strain changes and distribution characteristics of micro-seismic events underground in gas storage, intelligent comprehensive analysis and comprehensive analysis of all parameters and information of real-time online monitoring Evaluate, classify and classify various potential risks or accidents that affect the safe and stable operation of UGSs, and issue early warning signals and information on potential accident risks in a timely manner to ensure long-term stable and safe operation of UGSs.

The Distributed Fiber Acoustic Monitoring (DAS) technology uses a question-and-answer machine to send two clusters of laser pulses into the fiber. Part of the light is reflected back because the fiber is not absolutely pure. The Rayleigh wave of the backscattered light is affected by the sound wave and will produce a phase change. That is to say, the distance between two Rayleigh peaks will be affected by the sound wave and will change accordingly, and the sound wave amplitude on each meter of fiber can be determined through analysis and calculation. Effectively transforms an optical fiber into a string of acoustic signal sensors (or microphones) to identify fluid density, fluid migration, casing leaks or early detection of equipment wear and failure.

The Distributed Optical Fiber Thermometry System (DTS) is used to measure the temperature profile in the wellbore in real time. . After the high-power narrow-pulse-width laser pulse LD is incident on the sensing fiber, weak backscattered light is generated, which are Rayleigh, Anti-stokes and Stokes according to different wavelengths. (Stokes) Light. DTS is the most widely used distributed temperature monitoring technology. It can accurately measure the temperature of each meter on the optical fiber. The maximum operating temperature reaches 300°C, with an accuracy of 0.1°C and a resolution of 0.01°C.

Application of distributed optical fiber acoustic monitoring technology: fluid flow noise signal monitoring, micro-seismic monitoring, determination of productive section, calculation of fluid flow range, determination of well spacing and water plugging plan.

Application of distributed optical fiber acoustic wave monitoring technology + distributed optical fiber temperature measurement technology: fluid flow calculation, exploration and research on gas-oil-water distribution distinction. In the perforation section of oil and gas production wells, the noise characteristics and frequencies of oil, gas and water flowing into the well are different. We can distinguish whether the oil, gas or water flowing into the well is based on the recorded downhole noise characteristics and frequencies. water.

Use the temperature data measured by the downhole optical fiber, the noise data and pressure data measured by the optical fiber, and other parameters to calculate the flow rate: if there is a certain production layer in the production layer, in theory, as long as the production layer production is greater than zero, it means that the oil layer pressure in the production layer must be greater than the flow pressure in the well corresponding to this section.

Stress changes caused by fluid flow will lead to the opening or closing of tiny fractures in the formation, resulting in noise and microseismic signals. Through the distribution of noise and microseismic signals in different well sections downhole, the injection or production status of natural gas in different reservoir sections can be judged At the same time, by comprehensively analyzing the activities of gas injection wells and gas production wells in the normal production stage; analyzing whether the reservoir between different wells has effects such as stress interference, and analyzing the impact of different geological conditions on natural gas injection and production, according to the monitoring of the wells. The magnitude and time of occurrence of micro-seismic events and their distribution characteristics in the underground three-dimensional space of the gas storage, real-time monitoring and evaluation of various potential risks affecting the safe and smooth operation of the gas storage, and classification and timely release of potential accidents Risk warning signals and information to ensure long-term stable and safe operation of the gas storage.

Description of drawings

Fig. 1 is a schematic diagram of the distribution of various types of gas injection wells, gas production wells and monitoring wells and the layout of the downhole monitoring system of the underground gas storage according to the present invention.

Fig. 2 is a schematic diagram of the high-pressure natural gas injected into the underground by the gas injection well of the gas storage according to the present invention, which causes the underground high-pressure natural gas to leak to the ground by fracturing the tight caprock or activating the fault.

Fig. 3a is a schematic diagram of the sleeve structure and the sleeve outer armored optical cable of the present invention.

Figure 3b is a schematic diagram of the structure of the gas injection and production pipe and the armored optical cable on the outer wall of the gas injection and production pipe of the present invention.

Fig. 3c is a schematic diagram of the magnetic adsorption armored optical cable in the sleeve of the present invention.

3d is a schematic diagram of the layout of the three-component detector array in a part of the monitoring well of the present invention.

FIG. 4 is a schematic structural diagram of the first measurement armored optical cable of the present invention.

FIG. 5 is a schematic structural diagram of the second measurement armored optical cable of the present invention.

Detailed ways

The embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, but they do not constitute a limitation of the present invention, but are only examples, and at the same time, the advantages of the present invention will become clearer and easier to understand by explaining the advantages of the present invention.

A specific implementation of a long-term monitoring system for safe operation of an underground gas storage of the present invention is as follows:

As shown in Figure 1, a long-term monitoring system for safe operation of an underground gas storage includes a gas injection well 1, a gas production well 2, a monitoring well 3, and a metal casing 4. The metal casing 4 has a built-in gas injection and production pipe 5, and the outside of the metal casing 4 A first measurement armored optical cable 6 is fixed, a second measurement armored optical cable 7 is fixed on the outside of the gas injection and production pipe 5 in the well, and an armored optical cable 7 or a three-component detector with permanent magnet adsorption or electromagnetic induction adsorption is arranged in the monitoring well 3 Array 8, as shown in Figure 3c and Figure 3d;

As shown in Figure 3a, a first downhole quasi-distributed optical fiber pressure sensor 9 is fixed on the outside of the metal casing 4, and as shown in Figure 3b, a second downhole quasi-distributed optical fiber pressure sensor 10 is fixed on the outside of the inner gas injection and production pipe 5;

Also includes a composite modulation and demodulation instrument 11 placed near the wellhead;

The composite modulation and demodulation instrument 11 includes distributed acoustic sensing (DAS), distributed temperature sensing (DTS), distributed optical fiber strain/stress sensing (DSS) and quasi-distributed optical fiber pressure sensing (DPS) ; The composite modulation and demodulation instrument 11 is connected to the first measurement armored optical cable 6 and the second measurement armored optical cable 7 respectively.

As shown in FIG. 4 , the first measurement armored optical cable 6 and the second measurement armored optical cable 7 are both multi-parameter armored optical cables.

As shown in FIG. 4 , the first measurement armored optical cable 6 has at least two single-mode optical fibers 21 with high temperature resistance. Outside 21, a sensitive optical cable 23 for strain and vibration or noise is formed. The sensitive optical cable 23 is then tightly wrapped with a continuous stainless steel thin tube 25, and a knot or an extinction device 26 is installed at the end of each single-mode optical fiber 21 to prevent the single-mode optical fiber from being transmitted. The laser light incident on the top of the fiber 21 is reflected from the trailing end back to the top of the fiber.

As shown in FIG. 5 , there are at least two or more single-mode optical fibers 21 and two or more multi-mode optical fibers 22 in the second measurement armored optical cable 7 . The single-mode optical fibers 21 and the multi-mode optical fibers 22 are tightly wrapped with continuous inner The stainless steel thin tube 24, the inner continuous stainless steel thin tube 24 is filled with high temperature resistant optical fiber paste, the outer wall of the inner continuous stainless steel thin tube 24 is tightly sheathed with the outer continuous stainless steel thin tube 25, and the tail ends of the two multimode optical fibers 22 are welded together. It is fixed and protected by a U-shaped piece, and a light extinction device 26 is respectively tied or installed at the tail ends of all single-mode fibers 21 and the remaining multi-mode fibers 22 to prevent the top of the single-mode fibers 21 and the multi-mode fibers 22 from The laser light incident at the top of the fiber is reflected from the tail end back to the tip of the fiber.

The first downhole quasi-distributed pressure sensor 9 and the second downhole quasi-distributed pressure sensor 10 are Faber cavity optical fiber pressure sensors, or grating pressure sensors, or piezoelectric crystal pressure sensors.

A plurality of first downhole quasi-distributed pressure sensors 9 are connected in series at equal intervals through the second measurement armored optical cable 7 and the first measurement armored optical cable 6, as shown in Figure 3a;

A plurality of second downhole quasi-distributed pressure sensors 10 are connected in series at equal intervals through the second measurement armored optical cable 7, as shown in FIG. 3b.

As shown in Figure 3a, the first measurement armored optical cable 6 of the long-term dynamic monitoring system for the safe operation of the underground gas storage also includes a first annular metal clip 12, and the first annular metal clip 12 is installed and fixed on the Metal casing at 4 boots.

As shown in Fig. 3b, the second special measurement armored optical cable 7 further includes a second annular metal clip 13, which is installed and fixed on the outside of the gas injection and production pipe 5 in the well at equal intervals.

In the long-term monitoring system for the safe operation of the underground gas storage, the three-component detector array 8 arranged in the part of the monitoring well 3 can be a three-component electromagnetic detector or a three-component piezoelectric detector or a three-component acceleration detector or Three-component MEMS detector or three-component fiber detector.

The monitoring method for the safety operation monitoring system of the underground gas storage includes the following steps:

(1), in the newly drilled gas injection well 1, gas production well 2 and part of the monitoring well 3, the metal casing 4 and the first measurement armored optical cable 6 are synchronously and slowly lowered into the drilled well hole;

(2) Install the first annular metal clip 12 at the junction of the two metal sleeves 4 at the wellhead to fix and protect the first measurement armored optical cable 6 from rotating and/or during the process of running the sleeve. be damaged;

(3) Use a high-pressure pump truck to pump cement slurry into the bottom of the gas injection well 1, gas production well 2 and monitoring well 3, so that the cement slurry is returned from the bottom of the hole along the annulus between the outer wall of the metal casing 4 and the borehole. At the wellhead, after the cement slurry is consolidated, the metal casing 4, the first measurement armored optical cable 6 and the formation rock are permanently fixed together;

(4), put the injection-production gas pipe 5 and the second measurement armored optical cable 7 into the metal casing 4 well after the cementing and completion synchronously and slowly;

(5), at the wellhead, install the second annular metal clip 13 on the gas injection and production pipe 5 according to the same spacing, and fix and protect the second measurement armored optical cable 7 from being damaged during the installation of the gas injection and production pipe 5 in the downhole. damage and good acoustic signal coupling between the second measurement armored optical cable 7 and the coiled tubing;

(6) Connect the single-mode optical fiber 21 or the sensitive optical cable 23 in the first measurement armored optical cable 6 to the DAS signal input end of the composite modulation and demodulation instrument 11 at the wellhead, and connect the single-mode optical fiber 21 in the first measurement armored optical cable 6 A multimode optical fiber 22 or two multimode optical fibers 22 whose tail ends have been U-shaped fusion spliced are connected to the DTS signal input end (single-ended input or double-ended input) of the composite modem 11;

(7) Connect the single-mode optical fiber 21 or the sensitive optical cable 23 in the second measurement armored optical cable 7 to the DAS signal input end of the composite modulation and demodulation instrument 11 at the wellhead, and connect the single-mode optical fiber 21 in the second measurement armored optical cable 7 to the DAS signal input end of the composite modem A multimode optical fiber 22 or two multimode optical fibers 22 whose tail ends have been U-shaped fusion spliced are connected to the DTS signal input end (single-ended input or double-ended input) of the composite modem 11;

(8), connect the sensitive optical cable 23 in the first measurement armored optical cable 6 to the DSS signal input end of the composite modulation and demodulation instrument 11 at the wellhead;

(9), connect the first downhole quasi-distributed optical fiber pressure sensor (9) and the second downhole quasi-distributed optical fiber pressure sensor ( The optical fibers of 10) are respectively connected to the DPS signal input end of the composite modulation and demodulation instrument 11;

(10) In some monitoring wells 3 at the depth close to the gas storage layer, place the downhole three-component detector array 8, and push each stage of the three-component detector on the downhole three-component detector array 8 closely to the Go up the inner wall of the metal casing 4 or the well wall, and connect the armored optoelectronic composite cable connecting the three-component detector array in the well to the signal input end of the surface data acquisition instrument near the wellhead;

(11) During the normal production operation (gas injection or gas production) of the gas storage, the composite modulation and demodulation instrument 11 placed next to the wellhead continuously monitors and measures the first measurement armored optical cable 6 outside the metal casing 4 and the injection in the well The second outside the gas production pipe 5 measures the DAS and DTS signals in the armored optical cable 7, and at the same time continuously monitors and measures the first downhole quasi-distributed pressure sensor 9 and the second downhole quasi-distributed pressure sensor 9 connected in series outside the metal casing 4 and the outside of the in-hole gas injection and production pipe 5. Distributed pressure sensor 10 pressure signal;

(12) During the normal production operation (gas injection or gas production) of the gas storage, the composite modulation and demodulation instrument 11 placed beside the wellhead continuously monitors and measures the strain and the inner strain of the first measurement armored optical cable 6 outside the metal casing 4 DSS signal output from vibration- or noise-sensitive optical cable 23,

(13), modulate and demodulate the DAS signal, DTS signal, DSS signal and DPS signal continuously measured by the composite modulation and demodulation instrument 11, and convert the DAS data, DTS data, DSS data and DPS data into the whole well of all monitoring wells Segment noise intensity, temperature, stress (strain) and distribution data of pressure changes at each pressure sensor location;

(14), modulate and demodulate the DAS signals of all monitoring wells continuously measured by the composite modulation and demodulation instrument 11, convert the DAS data into the underground microseismic data recorded by the monitoring wells, and process the three-component geophones in some monitoring wells in real time Microseismic data recorded by the array;

(15) According to the monitored and measured downhole noise, temperature and pressure data of gas injection well 1 and gas production well 2, the multi-parameter comprehensive inversion method is used to calculate the gas flow rate of each gas injection well section and gas production well section downhole and its change, so as to realize the long-term real-time dynamic monitoring of the production process of gas injection and recovery of gas storage and the change of injection and recovery;

(16) According to the monitoring and measurement of the underground stress (strain) data of the outer casing of gas injection well 1, gas production well 2 and monitoring well 3, real-time online analysis finds the parts or well sections where casing damage may occur, and take timely measures. Repair or plugging measures for casing damaged parts to prevent major safety hazards or accidents in which the underground high-pressure natural gas leaks to the ground along the wall of gas injection well 1, gas production well 2 or monitoring well 3 where casing damage occurs;

(17), according to the first measurement armored optical cable 6 or the second measurement armored optical cable 7 in the gas injection well 1, the gas production well 2 and the monitoring well 3 or the three-component geophone array in the well to monitor the recorded underground microseismic events in real time According to the energy size and time-varying spatial distribution law of the gas storage, it can be judged online and real-time whether the normal gas injection and gas recovery operations of the gas storage have induced and activated the underground large and small faults, and whether the sealing caprock of the gas storage has been induced and activated by the high-pressure natural gas. Small faults, whether the activated small faults will damage the integrity of the sealed caprock of the gas storage, and whether there will be a major safety hazard or accident that the underground high-pressure natural gas leaks to the ground along the activated small faults on the sealed caprock, as shown in Figure 2 ;

(18) Comprehensively make full use of the first measurement armored optical cable 6 and the second measurement armored optical cable 7 arranged inside and outside the casing 4 of all the gas injection wells 1, gas production wells 2 and monitoring wells 3 of the gas storage and outside the gas injection and production pipe 5 in the well As well as some downhole three-component detector arrays arranged in monitoring wells, real-time online monitoring of all downhole noise, temperature, pressure, stress (strain) changes and distribution characteristics of microseismic events underground in gas storage, real-time online monitoring of all real-time online monitoring. Intelligent comprehensive analysis and evaluation of parameters and information, classification of various potential risks or accidents affecting the safe and stable operation of the gas storage, timely release of early warning signals and information of potential accident risks, to ensure long-term stable and safe operation of the gas storage .

Claims (9)

1. A long-term monitoring system for safe operation of an underground gas storage is characterized in that it comprises a gas injection well (1), a gas production well (2), a monitoring well (3), a metal casing (4), and the metal casing (4) has a built-in injection and production well (4). A gas pipe (5), a first measurement armored optical cable (6) is fixed on the outside of the metal sleeve (4), and a second measurement armored optical cable (7) is fixed on the outside of the gas injection and production pipe (5) in the well; the monitoring well ( 3) A second measurement armored optical cable (7) with permanent magnet adsorption or electromagnetic induction adsorption is arranged inside, or an underground three-component detector array (8) is also provided;

   A plurality of first downhole quasi-distributed optical fiber pressure sensors (9) are fixed on the outside of the metal casing (4), and a plurality of second downhole quasi-distributed optical fiber pressure sensors (10) are fixed on the outside of the gas injection and production pipe (5) in the well;

   Also includes a composite modulation and demodulation instrument (11) placed near the wellhead;

   The composite modulation and demodulation instrument (11) includes distributed acoustic wave sensing DAS, distributed temperature sensing DTS, distributed optical fiber strain/stress sensing DSS, and quasi-distributed optical fiber pressure sensing DPS; the composite modulation and demodulation instrument (11) are respectively connected with the first measurement armored optical cable (6) and the second measurement armored optical cable (7).
2. The long-term monitoring system for safe operation of an underground gas storage according to claim 1, wherein the first measurement armored optical cable (6) and the second measurement armored optical cable (7) are multi-parameter armored optical cables .
3. The long-term monitoring system for safe operation of an underground gas storage according to claim 2, characterized in that, there are at least two single-mode optical fibers (21) with high temperature resistance in the first measurement armored optical cable (6), and the The high temperature-resistant composite material is formed into a cylindrical shape by injection molding or extrusion and is tightly wrapped around the single-mode optical fiber (21) to form a strain/stress or vibration/noise sensitive optical cable (23), and the sensitive optical cable (23) is then tightly wrapped with continuous stainless steel A thin tube (25) is knotted at the tail end of each single-mode fiber (21) or a light extinction device (26) is installed to prevent the laser incident from the tip of the single-mode fiber (21) from being reflected back to the tip of the fiber from the tail end.
4. The long-term monitoring system for safe operation of an underground gas storage according to claim 2, characterized in that, there are at least two or more single-mode optical fibers (21) in the second measurement armored optical fiber cable (7), and more than two single-mode optical fibers (21). The mode optical fiber (22), the single-mode optical fiber (21) and the multimode optical fiber (22) are tightly wrapped with an inner continuous stainless steel thin tube (24), and the inner continuous stainless steel thin tube (24) is filled with high temperature resistant optical fiber paste, and the inner continuous stainless steel The outer wall of the thin tube (24) is tightly sheathed with an outer continuous stainless steel thin tube (25), wherein the tail ends of the two multimode optical fibers (22) are fused together, and the fusion joint is fixed and protected by a U-shaped piece. The ends of the optical fiber (21) and the remaining multimode optical fibers (22) are respectively knotted or installed with a light extinction device (26) to prevent the incident laser light from the top of the single-mode optical fiber (21) and the top of the multi-mode optical fiber (22) Reflects from the tail back to the tip of the fiber.
5. The safety operation monitoring system for an underground gas storage according to claim 1, wherein the first downhole quasi-distributed pressure sensor (9) and the second downhole quasi-distributed pressure sensor (10) are Faber Cavity fiber pressure sensor, or grating pressure sensor, or piezoelectric crystal pressure sensor;

   A plurality of first downhole quasi-distributed pressure sensors (9) are connected in series with equal intervals through the first measurement armored optical cable (6) in sequence;

   A plurality of second downhole quasi-distributed pressure sensors (10) are serially connected in series at equal intervals through the second measurement armored optical cable (7).
6. The long-term monitoring system for safe operation of an underground gas storage according to claim 1, further comprising a first annular metal clip (12), wherein the first annular metal clip (12) is installed and fixed on a metal sleeve ( 4) Boots.
7. The long-term dynamic monitoring of the safe operation of an underground gas storage according to claim 1, further comprising a second annular metal clip (13), the second annular metal clip (13) being installed and fixed at equal intervals in the well for injection Outside of the gas sampling pipe (5).
8. The long-term monitoring system for safe operation of an underground gas storage according to claim 1, wherein the three-component detector array (8) is a three-component electromagnetic detector, a three-component piezoelectric detector, a three-component acceleration detector One of the three-component MEMS detector, the three-component fiber detector.
9. The monitoring method for the safety operation monitoring system of an underground gas storage according to any one of claims 1 to 7, characterized in that, comprising the following steps:

   (a) In the newly drilled gas injection well (1), gas production well (2) and part of the monitoring well (3), lower the metal casing (4) and the first measurement armored optical cable (6) synchronously and slowly into the well-drilled well;

   (b), at the wellhead, install the first annular metal clip (12) at the connection of the two metal sleeves (4) to fix and protect the first measurement armored optical cable (6) from being damaged during the process of running the sleeve. can rotate and/or be damaged;

   (c), use a high-pressure pump truck to pump cement slurry into the bottom of the gas injection well (1), gas production well (2) and monitoring well (3), so that the cement slurry from the bottom of the hole along the outer wall of the metal casing (4) and the borehole The annular space between is returned to the wellhead, and after the cement slurry is consolidated, the metal casing (4), the first measurement armored optical cable (6) and the formation rock are permanently fixed together;

   (d), lowering the gas injection and production pipe (5) and the second measurement armoured optical cable (7) into the well of the metal casing (4) after the cementing and completion, synchronously and slowly;

   (e), at the wellhead, install the second annular metal clip (13) on the gas injection and production pipe (5) according to the same spacing, and fix and protect the second measurement armored optical cable (7) in the downhole injection and production pipe (5). 5) The installation process is not damaged and the second measurement armored optical cable (7) and the coiled tubing have good acoustic signal coupling;

   (f), at the wellhead, connect the single-mode optical fiber (21) or the sensitive optical cable (23) in the first measuring armored optical cable (6) to the DAS signal input end of the composite modulation and demodulation instrument (11), and connect the first The single multimode optical fiber (22) in the measurement armored optical cable (6) or the two multimode optical fibers (22) whose tail ends have been U-shaped spliced are connected to the DTS signal input end of the composite modulation and demodulation instrument (11). terminal input or double terminal input;

   (g), at the wellhead, connect the single-mode optical fiber (21) or sensitive optical cable (23) in the second measuring armored optical cable (7) to the DAS signal input end of the composite modulation and demodulation instrument (11), and connect the second The single multimode optical fiber (22) in the measurement armored optical cable (7) or the two multimode optical fibers (22) whose tail ends have been U-shaped spliced are connected to the DTS signal input end of the composite modulation and demodulation instrument (11). terminal input or double terminal input;

   (h), at the wellhead, connect the sensitive optical cable (23) in the first measuring armored optical cable (6) to the DSS signal input end of the composite modulation and demodulation instrument (11);

   (i), connect the first downhole quasi-distributed optical fiber pressure sensor (9) with the second downhole quasi-distributed optical fiber pressure sensor (9) at the wellhead The optical fibers of the optical fiber pressure sensor (10) are respectively connected to the DPS signal input ends of the composite modulation and demodulation instrument (11);

   (j), in some monitoring wells (3) at the depth close to the gas storage layer, place the downhole three-component detector array (8), and detect each stage of the three-component detector on the downhole three-component detector array (8). Push the detector tightly against the inner wall of the metal casing (4) or the well wall, and connect the armored optoelectronic composite cable connecting the three-component detector array downhole to the DAS signal input end of the composite modulation and demodulation tool (11) near the wellhead. ;

   (k) During the normal production operation of the gas storage, namely gas injection or gas production, the composite modulation and demodulation instrument (11) placed beside the wellhead is used to continuously monitor and measure the first measurement armored optical cable outside the metal casing (4). (6) and the second outside of the gas injection and production pipe (5) in the well to measure the DAS and DTS signals in the armored optical cable (7), and at the same time continuously monitor and measure the first serial connection outside the metal casing (4) and the outside of the gas injection and production pipe (5) in the well. A downhole quasi-distributed pressure sensor (9), a pressure signal of a second downhole quasi-distributed pressure sensor (10);

   (1) During the normal production operation of the gas storage, that is, during gas injection or gas production, the composite modulation and demodulation instrument (11) placed next to the wellhead is used to continuously monitor and measure the metal casing (4) outside the first measurement armored optical cable ( 6) The DSS signal output by the inner sensitive optical cable (23),

   (m), modulate and demodulate the DAS signal, DTS signal, DSS signal and DPS signal continuously measured by the composite modulation and demodulation instrument (11), and convert the DAS data, DTS data, DSS data and DPS data into the data of all monitoring wells The distribution data of noise intensity, temperature, stress/strain and pressure change at each pressure sensor position in the whole well section;

   (n), modulate and demodulate the DAS signals of all monitoring wells continuously measured by the composite modulation and demodulation instrument (11), convert the DAS data into the underground microseismic data recorded by the monitoring wells, and process the three-components in some monitoring wells in real time Microseismic data recorded by the geophone array;

   (o) According to the monitored and measured downhole noise, temperature and pressure data of the gas injection well (1) and gas production well (2), the multi-parameter comprehensive inversion method is used to calculate the downhole noise of each gas injection well section and gas production well section. Gas flow and its changes, so as to realize the long-term real-time dynamic monitoring of the production process of gas injection and gas recovery of the gas storage and the variation of injection and production;

   (p) According to the monitoring and measurement of the underground stress (strain) data of the gas injection well (1), the gas production well (2) and the monitoring well (3) of the outer casing of the whole well section, real-time online analysis finds the parts where casing damage may occur or well section, timely take measures to repair or plug the casing damage to prevent the occurrence of underground high-pressure natural gas from the gas storage to the surface along the wall of the gas injection well (1), gas production well (2) or monitoring well (3) where casing damage occurs A major safety hazard or accident leaked;

   (q), according to the first measurement armored optical cable (6) or the second measurement armored optical cable (7) in the gas injection well (1), the gas production well (2) and the monitoring well (3) or the three-component detector in the well Array real-time monitoring of the energy magnitude and time-varying spatial distribution of underground micro-seismic events recorded in real-time, online real-time determination of whether the normal gas injection and gas recovery operations of the gas storage have induced and activated underground large and small faults, and the sealing cover of the gas storage. Whether there are small faults activated by high-pressure natural gas on the layer, whether the activated small faults will destroy the integrity of the gas storage sealing caprock, and whether there will be underground high-pressure natural gas leaking to the ground along the activated small faults on the sealing caprocks major safety hazards or accidents;

   (r), make full use of all the gas injection wells (1), gas production wells (2) and monitoring wells (3), the inside and outside of the casing (4) and the first measurement armoured outside the gas injection and production pipes (5) in the gas storage. The optical fiber cable (6), the second measurement armored optical fiber cable (7), and the three-component geophone array arranged in part of the monitoring wells are used for real-time online monitoring of all downhole noise, temperature, pressure, stress/strain changes and underground gas storage. The distribution characteristics of micro-seismic events, carry out intelligent comprehensive analysis and evaluation of all parameters and information of real-time online monitoring, classify and classify various potential risks or accidents that affect the safe and stable operation of gas storage, and issue early warning of potential accident risks in a timely manner Signals and information to ensure long-term stable and safe operation of the gas storage.

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