CN115079250A - CO based on optical fiber sensing technology 2 System and method for address selection and safety monitoring of sealed storage location - Google Patents

Abstract

The invention provides CO based on optical fiber sensing technology ₂ A system and method for site selection and safe operation monitoring of sealed storage site includes CO ₂ Underground monitoring armored optical cables are arranged outside the casings of the injection well and the monitoring well and outside the injection pipe, and an underground three-component detector array is arranged in the monitoring well; quasi-distributed optical fiber pressure sensors are arranged on the outer side of the sleeve and the outer side of the injection pipe; a seismic source and a three-component detector or an embedded armored distributed three-component seismic signal sensing optical cable are distributed on the ground in a three-dimensional mode; the device also comprises a composite modulation and demodulation instrument placed on the ground. Comprehensive utilization of ground three-dimensional seismic data for CO ₂ Site selection for sealed storage and real-time on-line monitoringAll the changes of downhole noise, temperature, pressure, stress/strain, the distribution characteristics of microseism events and time-lapse seismic data, and all the parameters and information are intelligently and comprehensively analyzed and evaluated to influence CO ₂ And classifying various risks or accidents in safe operation of the sealed place in a grading way, and issuing early warning signals and information of accident risks in time.

Description

Site selection and safety monitoring system and method for CO2 storage based on optical fiber sensing technology

technical field

The invention belongs to the technical field of geophysical exploration and ground and well monitoring, in particular to a CO2 storage site selection and safety monitoring system and method based on optical fiber sensing technology.

Background technique

Carbon dioxide (CO ₂ ) storage refers to the capture, compression, and transport of carbon dioxide from large emission sources to selected locations for long-term storage, rather than release into the atmosphere. Carbon dioxide storage technology, especially geological storage, is receiving more and more attention and research. The United States, the European Union, Japan, and Australia have all formulated corresponding research plans to carry out theoretical, experimental, demonstration and applied research on carbon dioxide storage technology.

The basic principle of CO ₂ geological storage is to imitate the mechanism of storing fossil fuels in nature, and to store CO ₂ in the stratum. After the CO ₂ can be transported to an appropriate location by pipelines or vehicles, it can be injected into the stratum with specific geological conditions and specific depths. The proposed geological conditions suitable for CO ₂ geological storage include geological environments such as old oil and gas fields, difficult-to-exploit coal seams, and deep groundwater layers.

The ideal geological storage environment is deep coal seams with no commercial exploitation value (while promoting coal seam gas recovery) and oil fields (while promoting oil recovery), depleted natural gas fields, and deep saline aquifers. In each type, the geological sequestration of _CO2 injects _CO2 compression fluids into subterranean rock formations. The storage depth is generally below 800 meters, and the temperature and pressure conditions at this depth can make CO ₂ in a high-density liquid or supercritical state. The time span during which carbon dioxide is buried is thousands or even tens of thousands of years. In order to prevent carbon dioxide from returning to the surface or migrating to other places under the action of pressure, the geological structure must meet the characteristics of caprock, reservoir and trap structure to achieve safety and effectiveness. buried.

Conventional geological trap structures include oil fields, gas fields and hydrocarbon-free gas reservoirs (mainly deep saline aquifers). For the first two, it is relatively easy to utilize them to store _CO2 due to familiarity with the structure and geology of the developed oil and gas fields. There are two advantages to using saline aquifers for storage: one is that trap structures in saline aquifers are more common than oil and gas fields; the other is that there may be some huge anticline gas storage structures suitable for _CO2 storage in saline aquifers. In addition, another difference is that after _{CO 2} is injected into the saline aquifer, it can be stable in the aquifer for tens of thousands of years after the hydrodynamic reaction. The _CO2 is converted into harmless carbonates that can be stored for millions of years.

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.

In the long-term high-pressure gas injection and storage operation of CO ₂ injection and geological storage, the cementing cement sheath outside the casing of the CO ₂ injection well or monitoring well will gradually cause loosening and damage under the influence of high pore fluid pressure, and underground in-situ stress The sudden change or accumulation of sections can also cause damage and deformation of the underground casing, resulting in potential safety risks and accidents of underground high-pressure _CO2 gas leaking to the surface along the annulus between the outer wall of the casing of the injection well or the monitoring well and the borehole. In addition, when high-pressure _CO2 gas is injected into the subsurface through a _CO2 injection well, the high-pressure fluid in the pores of the _CO2 geological seal storage layer may induce activation of subsurface faults. If there are large and small faults activated by high pressure CO ₂ gas on the sealing caprock of the CO ₂ injection and geological storage site, the activated faults may destroy the integrity of the sealing cap rock of the CO ₂ injection and geological storage site, causing underground A major safety hazard or accident caused by the leakage of high-pressure _CO2 gas to the ground along the activated fault on the sealing cap. Therefore, the underground CO ₂ injection and geological storage area urgently needs a real-time online monitoring system for the hidden dangers and accidents of high-pressure CO ₂ gas leakage to the ground that can ensure its long-term safe and stable operation.

SUMMARY OF THE INVENTION

In order to enable the long-term safe and stable operation of the underground CO ₂ injection and geological storage area, there will be no leakage of underground high-pressure CO ₂ gas to the ground along the annulus between the outer wall of the casing of the CO ₂ injection well or monitoring well and the formation, or along the The rupture zone of the fault located in the above-ground sealing caprock of CO ₂ injection and geological storage activated by underground high-pressure CO ₂ gas leaks to the ground. The CO ₂ injection and geological storage area needs to have long-term real-time dynamic monitoring of underground high-pressure CO ₂ gas leakage to the ground. A system of hidden dangers and accidents. The purpose of the invention is to provide a CO2 storage site selection, safety monitoring system and monitoring method based on optical fiber sensing technology, so as to solve the problems raised in the above background technology.

In order to solve the above-mentioned technical problems, the present invention adopts the following scheme:

The _CO2 storage site selection and safety monitoring system based on optical fiber sensing technology includes _CO2 injection wells, _CO2 monitoring wells and metal casings. The metal casings are arranged in the _CO2 injection wells and _CO2 monitoring wells. The _CO2 injection well also includes a _CO2 injection pipe, and the _CO2 injection pipe is installed in the metal casing;

A first downhole monitoring armored optical cable is fixed on the outside of the metal casing of the _CO2 injection well and _CO2 monitoring well, and a second downhole monitoring armored optical cable is fixed on the outside of the _CO2 injection pipe in the _CO2 injection well. The _CO2 monitoring A downhole three-component geophone array and/or other types of monitoring instruments are also arranged in the metal casing of the well;

A first downhole quasi-distributed pressure sensor array is fixed on the outside of the metal casing, and a second downhole quasi-distributed pressure sensor array is fixed on the outside of the CO ₂ injection pipe;

It also includes wired or wireless node-type ground three-component geophones arranged on the ground in a three-dimensional manner, or embedded armored helical optical cables or armored distributed three-component seismic signal sensing cables, and three-dimensional ground seismic sources;

Also includes composite modulation and demodulation instruments placed near the wellhead of the CO ₂ monitoring well;

The composite modulation and demodulation instrument includes three-component distributed optical fiber acoustic wave sensing DAS, distributed optical fiber temperature sensing DTS, distributed optical fiber strain/stress sensing DSS and quasi-distributed optical fiber pressure sensing DPS; The instrument is respectively connected with the embedded armored spiral optical cable or armored distributed three-component seismic signal sensing optical cable, the first underground monitoring armored optical cable and the second underground monitoring armored optical cable.

Further, the first downhole monitoring armored optical cable and the second downhole monitoring armored optical cable are both multi-parameter armored optical cables.

Further, in the first downhole monitoring armored optical cable, there is an armored spiral optical cable or an armored distributed three-component seismic signal sensing optical cable, at least two or more single-mode optical fibers that are resistant to high temperature and hydrogen loss and two The above high temperature resistant and hydrogen loss resistant multimode optical fibers are made of high temperature resistant and high strength composite materials by injection molding or extrusion into a cylindrical shape and tightly wrapped around one of the single-mode optical fibers to form a strain/stress sensitive optical cable. The first continuous stainless steel thin tube is tightly wrapped, and the other single-mode optical fibers and multi-mode optical fibers are respectively wrapped with a first continuous stainless steel thin tube. The inside of the wrapped first continuous stainless steel thin tube is filled with high-temperature resistant fiber paste. The outermost side of the optical fiber cable is a tightly wrapped second continuous stainless steel thin tube. Knot or install a light extinction device 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.

Further, in the second downhole monitoring armored optical cable, there are at least two or more single-mode fibers that are resistant to high temperature and hydrogen loss, and two or more multi-mode fibers that are resistant to high temperature and hydrogen loss, single-mode fibers and multi-mode fibers. It is wrapped in the same first continuous stainless steel thin tube, and the inside of the first continuous stainless steel thin tube is filled with high-temperature resistant optical fiber paste. 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. The first continuous stainless steel thin tube is tightly wrapped with the second continuous stainless steel thin tube, and a knot or an extinction device is installed at the tail end of all single-mode fibers to prevent the laser incident from the top of the single-mode fiber from being reflected back to the fiber from the tail end. top.

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

The first downhole quasi-distributed pressure sensor arrays are sequentially connected in series through the first downhole monitoring armored optical cables at equal intervals;

The second downhole quasi-distributed pressure sensor arrays are sequentially connected in series through the second downhole monitoring armored optical cables at equal intervals.

Further, the armored distributed three-component seismic signal sensing optical cable contains a square high temperature resistant elastomer, four high temperature resistant and hydrogen loss resistant single-mode optical fibers are laid on four sides of the elastomer, and a high temperature resistant single-mode optical fiber is inlaid in the center of the elastomer. Hydrogen loss-resistant single-mode optical fiber, the seismic signal sensing optical cable with single-mode optical fiber is tightly wrapped with a circular high-temperature resistant and corrosion-resistant high-strength composite material protective sheath, and the composite material protective sheath is surrounded by stainless steel armored steel wire protective armor Install distributed three-component seismic signal sensing optical cable.

Further, it also includes a first annular metal clip, the first annular metal clip is installed and fixed at the metal casing shoe; it also includes a second annular metal clip, the second annular metal clip is installed and fixed at equal intervals on the CO ₂ The outside of the injection tube.

Further, the downhole three-component detector array and the ground three-component detector are three-component electromagnetic detectors, three-component piezoelectric detectors, three-component acceleration detectors, three-component MEMS detectors, three-component digital detectors, three-component One of the component fiber optic detectors.

Further, the three-dimensionally arranged vibrators on the ground are longitudinal wave vibroseis and shear wave vibrators, directional well artillery vibrators, gas explosion longitudinal wave vibrators and gas explosion shear waves, electric spark vibrators, air gun vibrators, heavy hammer vibrators, and fixed eccentrics. One of the epicenters.

The invention also discloses a CO ₂ storage site selection and safety monitoring method based on optical fiber sensing technology, which comprises the following steps:

(a) According to the form and characteristics of the regional geological structure, preliminarily confirm the candidate sites of CO ₂ storage sites, and search for no fault crossing, no strong tectonic movement and damage, flat surface and convenient transportation according to the regional geological structure data. , large intact anticline tectonic areas away from densely populated cities or subterranean large salt dome tectonic belts as candidate sites for _CO2 storage;

(b) Arrange ground three-component geophones or buried armored helical optical cables or armored distributed three-component seismic signal sensing cables on the ground at the candidate sites of CO ₂ storage sites according to the pre-designed three-dimensional survey network;

(c) Measure and mark the source position on the ground at the candidate site of the CO ₂ storage site according to the pre-designed three-dimensional survey network;

(d) According to the three-dimensional three-component seismic data acquisition design, the longitudinal wave source signal and two orthogonal shear wave source signals of the full-wave field are excited in sequence at each designed source position, and the three-dimensional three-component ground earthquake is collected by the ground three-component geophone. data, or ground three-component geophone or armored helical fiber optic cable or armored distributed three-component seismic signal sensing cable with armored helical fiber optic cable outside metal casing or armored distributed three-component seismic signal sensing cable and downhole three The component detector array synchronously and jointly collects three-dimensional three-component surface well seismic data;

(e) Use ground 3D three-component seismic data or well-ground combined 3D three-component surface well seismic data to perform high-precision amplitude-preserving structural migration imaging processing and attribute extraction of various amplitude-preserving seismic data, including P-wave velocity Data volume, Shear wave velocity data volume, P/S wave velocity ratio data volume, P-wave velocity anisotropy data volume, Shear wave anisotropy data volume, Coherent data volume, Ant data volume, Section parameter data volume for automatic fault extraction, Fracture zone distribution Data volume, underground stress field distribution data volume, etc., use migration imaging profiles and various seismic data attribute bodies to comprehensively interpret and evaluate the geological structure of candidate CO ₂ storage sites, and fully study the high-precision structure migration imaging results to understand The distribution characteristics and laws of faults in the underground anticline structure in the CO ₂ storage area, comprehensively evaluate the influence and damage degree of the underground anticline structure suffered by strong tectonic movement, and use various property parameters of preserved amplitude processing seismic data and logging data to evaluate the proposed model. For the important reservoir parameters such as burial depth, thickness, extension, porosity, permeability, connectivity, etc. of the reservoir for CO ₂ storage, the selected regional geological structure is stable, and there are no major overlying strata and small interlayer faults cut by large faults. and fracture zones are not developed, the underground stress field is evenly distributed, the overlying stratum contains shale, mudstone and clay layers with very good sealing, extremely low porosity and permeability, and has a complete large-scale anticline structure as a suitable CO ₂ place of storage;

(f) Select a suitable CO ₂ storage site for the newly drilled CO ₂ injection well and CO ₂ monitoring well, and run the metal casing and the first downhole monitoring armored optical cable synchronously and slowly into the completed CO ₂ injection well and In the wellbore of the _CO2 monitoring well;

(g), install the described first annular metal clip at the junction of the two metal casings at the wellhead of the _CO2 injection well and the _CO2 monitoring well, to fix and protect the first downhole monitoring armored optical cable in the process of running the casing will not rotate and/or be damaged;

(h) Use a high-pressure pump truck to pump cement slurry to the bottom of the CO ₂ injection well and CO ₂ monitoring well, so that the cement slurry is returned to the wellhead from the bottom of the hole along the annulus between the outer wall of the metal casing and the borehole, and the cement After the slurry is consolidated, the metal casing, the first downhole monitoring armored optical cable and the formation rock are permanently fixed together;

(i), run the CO ₂ injection pipe and the second downhole monitoring armored optical cable into the metal casing well after the cementing and completion of the CO ₂ injection well synchronously and slowly;

(j), at the wellhead of the _CO2 injection well, install the second annular metal clip on the _CO2 injection pipe according to the same spacing, and fix and protect the second downhole monitoring armored optical cable during the installation process of the lower _CO2 injection pipe will not rotate and/or be damaged;

(k) Connect the armored spiral optical cable or armored distributed three-component seismic signal sensing cable in the first downhole monitoring armored optical cable to the composite modulation and demodulation instrument at the wellhead of the CO ₂ injection well and the CO ₂ monitoring well The DAS signal input end of the first downhole monitoring armored optical cable is connected to the single-end or dual-end DTS signal input end of the composite modulation and demodulation instrument. The terminal input terminal connects the first downhole sensitive optical cable for monitoring the strain/stress in the armored optical cable to the DSS signal input terminal of the composite modulation and demodulation instrument;

(1), at the wellhead of the CO ₂ monitoring well, connect the single-mode optical fiber in the second downhole monitoring armored optical cable to the DAS signal input end of the composite modulation and demodulation instrument, and connect the single multi-mode fiber in the second downhole monitoring armored optical cable to the DAS signal input end of the composite modulation and demodulation instrument. The mode fiber or the multimode fiber whose two ends have been U-shaped fusion spliced are connected to the single-ended input end of the DTS signal of the composite modulation and demodulation instrument and the double-ended input end;

(m), connect the optical fibers of the first downhole monitoring armored optical cable and the second downhole monitoring armored optical cable to the first downhole quasi-distributed pressure sensor array and the second downhole quasi-distributed pressure sensor array respectively to the composite modulation and demodulation DPS signal input terminal of the instrument;

(n), at the depth of the CO ₂ monitoring well close to the CO ₂ injection layer, place the downhole three-component detector array and/or other types of monitoring instruments, and detect each stage of the three-component detector on the downhole three-component detector array. Push the detector tightly against the inner wall of the metal casing or the well wall, and connect the armored optoelectronic composite cable connecting the three-component fiber optic detector array downhole to the DAS signal input end of the composite modulation and demodulation instrument near the wellhead;

(o) Connect the ground-buried armored spiral optical cable or armored distributed three-component seismic signal sensing cable to the DAS signal input end of the composite modulation and demodulation instrument, or connect the ground-laid wired three-component detector (11 ) connected to ground seismic data acquisition instruments;

(p) During the normal operation of the CO ₂ storage system, that is, during the injection and storage of CO ₂ , through the composite modulation and demodulation instrument and the ground three-component geophone or armored helical optical cable or armored distributed three-component seismic signal connected to it. The photosensitive cable, as well as the first downhole monitoring armored optical cable and the second downhole monitoring armored optical cable and the downhole three-component geophone array, continuously and synchronously carry out the combined microseismic monitoring of the surface and the well, and continuously monitor the CO ₂ injection well and the monitoring well. The first downhole monitoring the armored optical cable outside the metal casing and the second downhole monitoring the DAS and DTS signals inside the armored optical cable outside the _CO2 injection pipe, while continuously monitoring and measuring the first outside the metal casing and the outside of the _CO2 injection pipe in series Downhole quasi-distributed pressure sensor array, the pressure signal of the second downhole quasi-distributed pressure sensor array;

(q) During the normal production operation of CO ₂ storage, that is, the CO ₂ injection pipe or the storage period, the DSS signal output from the sensitive optical cable in the first downhole monitoring armored optical cable outside the metal casing is continuously monitored and measured by the composite modulation and demodulation instrument;

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

(s), modulate and demodulate the DAS signals in all ground and monitoring wells continuously measured by the composite modulation and demodulation instrument, convert the DAS data into underground microseismic data recorded by the ground and monitoring wells, and process the _CO2 monitoring wells in real time Microseismic data recorded by downhole three-component geophone arrays;

(t), according to the monitored and measured downhole noise, temperature and pressure data of _CO2 injection wells and _CO2 monitoring wells, use the multi-parameter comprehensive inversion method to calculate the _CO2 gas flow rate of each _CO2 injection well section downhole and its changes, so as to realize long-term real-time dynamic monitoring of the process of CO ₂ injection and storage and its changes in CO ₂ injection;

(u) According to the monitoring and measurement of the subsurface stress (strain) data of the metal casing of the CO ₂ injection well and the CO ₂ monitoring well in the whole well section, real-time online analysis finds the parts or well sections where casing damage may occur, and timely measures the casing damage. Repair or plugging measures for damaged parts to prevent major safety hazards or accidents in which high-pressure CO ₂ gas injected and stored underground leaks to the ground along the wall of the CO ₂ injection well or CO ₂ monitoring well where casing damage occurs;

(v), according to the first downhole monitoring armored fiber optic cable in the ground three-component geophone, the embedded armored helical fiber optic cable or the armored distributed three-component seismic signal sensing cable and the CO ₂ injection well and the CO ₂ monitoring well or The second downhole monitoring armored optical cable or three-component geophone array in the well monitors and records the energy magnitude and time-varying spatial distribution of the underground microseismic events in real time, so as to determine the normal CO ₂ injection operation or storage time in the CO ₂ storage site in real time online. Whether the underground large and small faults are induced and activated, whether there are small faults induced and activated by high pressure _CO2 gas on the sealing caprock of the anticline structure for underground _CO2 injection and storage, and whether the activated small faults will destroy the _CO2 injection and storage area The integrity of the sealing caprock, whether there will be a major safety hazard or accident that the high-pressure _CO2 gas injected and stored underground leaks to the ground along the activated small faults on the sealing caprock;

(w) Comprehensively make full use of ground three-component geophones or embedded armored helical optical cables or armored distributed three-component seismic signal sensing cables and all CO ₂ injection wells and CO ₂ monitoring wells in underground injection and storage areas, The first downhole monitoring armored optical cable, the second downhole monitoring armored optical cable, and the downhole three-component detector array arranged in the monitoring well, which are arranged inside and outside the metal casing and the CO ₂ injection pipe, can monitor all downhole noise, temperature and pressure online in real time. , stress/strain changes and the distribution characteristics of micro-seismic events underground for CO ₂ injection and storage, intelligent and comprehensive analysis and evaluation of all parameters and information of real-time online monitoring, and the impact on the safe and stable operation of CO ₂ injection and sealing areas. Various potential risks or accidents are classified and classified, and early warning signals and information on potential high-pressure CO ₂ gas leakage accidents are released in a timely manner to ensure long-term stable and safe operation of CO ₂ injection and storage areas;

(x) Re-excitation of full-wavefield sources at all source locations on the ground every 3 or 6 months, ground three-component geophones, buried armored helical fiber optic cables, or armored distributed three-component seismic signals The sensing optical cable, the first downhole monitoring armored optical cable, the second downhole monitoring armored optical cable and the downhole three-component geophone array are synchronously and jointly collected three-dimensional three-component time-lapse surface well seismic data;

(y) Perform high-precision migration imaging processing on the three-dimensional three-component time-lapse surface well seismic data jointly collected by the well and the ground, and extract various seismic attributes of the data, such as longitudinal wave velocity, shear wave velocity, and shear wave velocity. Velocity, P-wave impedance, S-wave impedance, Poisson's ratio, P-wave velocity ratio, S-wave velocity ratio, P-wave amplitude ratio, S-wave amplitude ratio, P-wave impedance ratio, S-wave impedance ratio, P-wave Q ratio, S-wave Q ratio, etc. , according to the time-lapse changes of the distribution range of various 3D seismic attribute data volumes, to understand and monitor the migration and distribution range of the high-pressure _CO2 gas injected into the underground reservoir in the anticline structural reservoir with time. CO ₂ gas has migrated to areas or formations other than the anticline structural reservoir. It is necessary to release early warning signals and information of potential high-pressure CO ₂ gas leakage accident risks in time to ensure long-term stable and safe operation of CO ₂ injection and storage areas.

The beneficial effects that the present invention has:

The present invention can use well-ground joint acquisition of three-dimensional three-component surface well seismic data to perform high-precision amplitude-preserving structural migration imaging processing and attribute extraction of multiple amplitude-preserving processed seismic data, and fully study the high-precision structural migration imaging results. Understand the distribution characteristics and laws of faults in the underground anticline structure in the CO ₂ storage area, comprehensively evaluate the impact and damage degree of the underground anticline structure subjected to strong tectonic movement, and use various amplitude preservation to process the attribute parameters of seismic data and the evaluation of logging data The important reservoir parameters such as burial depth, thickness, extension, porosity, permeability, connectivity, etc. of the reservoir to be used for CO ₂ storage should be selected, and a safe and appropriate CO ₂ storage site should be selected.

Comprehensively make full use of ground three-component geophones or armored optical cables, monitoring armored optical cables arranged inside and outside the casing of all underground CO ₂ injection wells and monitoring wells and outside the injection pipes, and underground three-component geophone arrays arranged in monitoring wells, real-time online Monitor all downhole noise, temperature, pressure, stress/strain changes and the distribution characteristics of micro-seismic events underground for _CO injection and storage, and combine time-lapse seismic data processing and interpretation results to conduct real-time online monitoring of all parameters and information. Intelligent comprehensive analysis and evaluation, classify and classify various potential risks or accidents affecting the safe and smooth operation of CO ₂ injection and sealing areas, and timely release early warning signals and information of potential high-pressure CO ₂ gas leakage accident risks to ensure CO ₂ injection. And the long-term stable and safe operation of the storage area.

Description of drawings

1 is a schematic cross-sectional view of the distribution of CO ₂ injection wells and monitoring wells in the CO ₂ injection and geological storage area of the present invention, and the layout of surface and downhole monitoring systems.

2 is a schematic plan view of the distribution of CO ₂ injection wells and monitoring wells in the CO ₂ injection and geological storage area of the present invention, and the layout of the surface and downhole monitoring systems.

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

Figure 3b is a schematic diagram of the structure of the CO ₂ injection pipe and the outer wall armored optical cable of the CO ₂ injection pipe of the present invention.

Figure 3c is a schematic structural diagram of the distributed three-component seismic signal sensing optical cable of the present invention.

3d is a schematic cross-sectional view of the structure of the distributed three-component seismic signal sensing optical cable of the present invention.

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

4 is a schematic structural diagram of the first downhole monitoring armored optical cable of the present invention.

5 is a schematic structural diagram of the second downhole monitoring armored optical cable of the present invention.

Reference number:

1. _CO2 injection well; 2. _CO2 monitoring well; 3. Metal casing; 4. _CO2 injection pipe; 5. The first downhole monitoring armored optical cable; 6. The second downhole monitoring armored optical cable; 7. Downhole Three-component geophone array; 8. Monitoring instrument; 9. First downhole quasi-distributed pressure sensor array; 10. Second downhole quasi-distributed pressure sensor array; 11. Ground three-component geophone; 12. Armored spiral optical cable; 13. Armored distributed three-component seismic signal sensing optical cable; 14. Seismic source; 15. Composite modulation and demodulation instrument; 16. Elastomer; 17. Composite material protective sleeve; 18. The first ring-shaped metal clip; Ring metal clip; 21. Single-mode optical fiber; 22. Multi-mode optical fiber; 23. Sensitive optical cable; 24. First continuous stainless steel thin tube; 25. Second continuous stainless steel thin tube; 26. Extinction device.

Detailed ways

The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal" , "inside", "outside", "front", "rear", "top", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the attached drawings, or when the invention product is used The usual orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a Invention limitations.

In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "arranged", "opened", "installed", "connected" and "connected" should be understood in a broad sense, for example, It can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Example

As shown in Figure 1, a _CO2 storage site selection and safety monitoring system based on optical fiber sensing technology includes a _CO2 injection well 1, a _CO2 monitoring well 2 and a metal casing 3, the metal casing 3 is set in the CO2 _2. In the injection well 1 and the CO ₂ monitoring well 2, the CO ₂ injection well 1 also includes a CO ₂ injection pipe 4, and the CO ₂ injection pipe 4 is installed in the metal casing 3;

As shown in Figure 3a, Figure 3b and Figure 3e, the first downhole monitoring armored optical cable 5 is fixed on the outside of the metal casing 3 of the CO ₂ injection well 1 and the CO ₂ monitoring well 2, and the CO ₂ injection in the CO ₂ injection well 1 A second downhole monitoring armored optical cable 6 is fixed on the outside of the pipe 4, and an underground three-component detector array 7 and/or other types of monitoring instruments 8 are also arranged in the CO ₂ monitoring well 2;

As shown in Figure 3a, a first downhole quasi-distributed pressure sensor array 9 is fixed on the outside of the metal casing 3, and a second downhole quasi-distributed pressure sensor array 10 is fixed on the outside of the CO ₂ injection pipe 4;

As shown in FIG. 1 and FIG. 2 , it also includes three-component ground three-component detectors 11 of wired or wireless node type, embedded armored helical optical cables 12 or armored distributed three-component seismic signal sensing cables 13 arranged in a three-dimensional manner on the ground, and Three-dimensionally arranged seismic source 14 on the ground;

Also includes a composite modulation and demodulation instrument 15 placed near the wellhead of the CO ₂ monitoring well 2;

The composite modulation and demodulation instrument 15 includes three-component distributed optical fiber acoustic wave sensing DAS, distributed optical fiber temperature sensing DTS, distributed optical fiber strain/stress sensing DSS and quasi-distributed optical fiber pressure sensing DPS; The adjusting instrument 15 is respectively connected with the embedded armored helical optical cable 12 or the armored distributed three-component seismic signal sensing optical cable 13 , the first monitoring armored optical cable 5 and the second monitoring armored optical cable 6 .

As shown in Figures 4 and 5, the first downhole monitoring armored optical cable 5 has an armored spiral optical cable 12 or an armored distributed three-component seismic signal sensing optical cable 13, and at least two or more high temperature resistant The hydrogen-loss single-mode optical fiber 21 and two or more high-temperature-resistant and hydrogen-loss-resistant multi-mode optical fibers 22 are formed by injection molding or extruding the high-temperature-resistant and high-strength composite material into a cylindrical shape and tightly wrapping one of the single-mode optical fibers 21, A strain/stress sensitive optical cable 23 is formed. The sensitive optical cable 23 is tightly wrapped with a first continuous stainless steel thin tube 24, and the remaining single-mode optical fibers 21 and multimode optical fibers 22 are tightly wrapped with a first continuous stainless steel thin tube 24. The first continuous stainless steel thin tube 24 is filled with high temperature resistant optical fiber paste, and the outermost side of the first downhole monitoring armored optical cable 5 is the second continuous stainless steel thin tube 25 tightly wrapped to increase the compressive and tensile strength of the first underground monitoring armored optical cable 5 , and knot or install a light extinction device 26 at the end of each single-mode fiber 21 to prevent the laser light incident from the top of the single-mode fiber 21 from being reflected back to the top of the fiber from the end.

The second downhole monitoring armored optical cable 6 has at least two or more single-mode optical fibers 21 that are resistant to high temperature and hydrogen loss, and two or more multi-mode optical fibers 22 that are resistant to high temperature and hydrogen loss, single-mode optical fibers 21 and multi-mode optical fibers. 22 is tightly wrapped in the same first continuous stainless steel thin tube 24, the first continuous stainless steel thin tube 24 is filled with high temperature resistant optical fiber paste, and the tail ends of the two multimode optical fibers 22 are fused together, and the fusion joint is fixed with a U-shaped piece And to protect it, the second continuous stainless steel thin tube 25 is tightly wrapped outside the first continuous stainless steel thin tube 24 to increase the compressive and tensile strength of the second downhole monitoring armored optical cable 6. An extinction device 26 is knotted or installed to prevent the laser light incident from the tip of the single-mode fiber 21 from being reflected back from the tail end to the tip of the fiber.

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

The first downhole quasi-distributed pressure sensor arrays 9 are connected in series at equal intervals through the first downhole monitoring armored optical cables 5 in sequence;

The second downhole quasi-distributed pressure sensor arrays 10 are sequentially connected in series through the second downhole monitoring armored optical cables 6 at equal intervals.

As shown in FIG. 3c and FIG. 3d, the distributed three-component seismic signal sensing optical cable 13 includes a square high temperature resistant elastic body 16, and four high temperature resistant and hydrogen loss resistant single-mode optical fibers 21 are laid on the four sides of the elastic body 16. A single-mode optical fiber 21 that is resistant to high temperature and hydrogen loss is inlaid in the center of the elastomer, and the seismic signal sensing optical cable with the single-mode optical fiber 21 is tightly wrapped with a circular high-strength composite material protective sleeve 17 that is resistant to high temperature and corrosion, and the composite material The protective sleeve 17 is surrounded by stainless steel armored steel wires to protect the distributed three-component seismic signal sensing optical cable 13 .

As shown in Figures 3a and 3b, it also includes a first annular metal clip 18, the first annular metal clip 18 is installed and fixed at the metal sleeve 3 shoe; and a second annular metal clip 19, the second annular metal clip 19 is included. Ring-shaped metal clips 19 are installed and fixed on the outside of the CO ₂ injection pipe 4 at equal intervals.

The downhole three-component detector array 7 and the ground three-component detector 11 are a three-component electromagnetic detector, a three-component piezoelectric detector, a three-component acceleration detector, a three-component MEMS detector, a three-component digital detector, a three-component One of the fiber optic detectors.

The three-dimensionally arranged vibrators 14 on the ground are longitudinal wave vibroseis and shear wave vibrators, directional well gun vibrators, gas explosion longitudinal wave vibrators and gas explosion shear waves, electric spark vibrators, air gun vibrators, heavy hammer vibrators, and fixed eccentric wheel vibrators. a kind of.

The technical solution also includes a CO ₂ storage site selection and safety monitoring method based on optical fiber sensing technology, including the following steps:

(a) According to the regional geological structure morphology and characteristic data, preliminarily confirm the candidate sites of CO ₂ storage sites, and look for no large or small faults to cross, no strong tectonic movement impact and damage, flat surface, convenient transportation, far away from densely populated areas Large intact anticline tectonic areas in cities or subterranean large salt dome tectonic zones are candidate sites for _CO2 storage;

(b), on the ground of the candidate site of the CO ₂ storage site, according to the pre-designed three-dimensional survey network, lay the ground three-component geophone 11 or the embedded armored spiral optical cable 12 or the armored distributed three-component seismic signal sensing cable 13;

(c) Measure and mark the position of the source 14 on the ground of the candidate site of the CO ₂ storage site according to the pre-designed three-dimensional survey network. If a fixed eccentric source is used for excitation, dig a pit and pour cement at the position of each source 14 A pile on which a fixed eccentric vibration source is mounted;

(d) According to the three-dimensional three-component seismic data acquisition design, the longitudinal wave source signal and two orthogonal shear wave source signals of the full wave field are excited in sequence at each designed source 14 position, and the ground three-component detector 11 collects the three-dimensional three-component seismic data. Ground seismic data, or ground three-component geophone 11 or armored helical optical cable 12 or armored distributed three-component seismic signal sensing cable 13 and armored helical optical cable 12 outside the metal sleeve 3 or armored distributed three-component seismic The signal sensing optical cable 13 and the downhole three-component geophone array 7 synchronously and jointly collect three-dimensional three-component surface well seismic data;

(e) Use ground 3D three-component seismic data or well-ground combined 3D three-component surface well seismic data to perform high-precision amplitude-preserving structural migration imaging processing and attribute extraction of various amplitude-preserving seismic data, including P-wave velocity Data volume, Shear wave velocity data volume, P/S wave velocity ratio data volume, P-wave velocity anisotropy data volume, Shear wave anisotropy data volume, Coherent data volume, Ant data volume, Section parameter data volume for automatic fault extraction, Fracture zone distribution Data volume, underground stress field distribution data volume, etc., use migration imaging profiles and various seismic data attribute bodies to comprehensively interpret and evaluate the geological structure of candidate CO ₂ storage sites, and fully study the high-precision structure migration imaging results to understand The distribution characteristics and laws of faults in the underground anticline structure in the CO ₂ storage area, comprehensively evaluate the influence and damage degree of the underground anticline structure suffered by strong tectonic movement, and use various property parameters of preserved amplitude processing seismic data and logging data to evaluate the proposed model. For the important reservoir parameters such as burial depth, thickness, extension, porosity, permeability, connectivity, etc. of the reservoir for CO ₂ storage, the selected regional geological structure is stable, and there are no major overlying strata and small interlayer faults cut by large faults. It is the most suitable and safest place to be the most suitable and safest, with no development of fracture zones, uniform distribution of underground stress field, shale, mudstone and clay layers with very good sealing properties, extremely low porosity and permeability, and complete large-scale anticline structure. of CO ₂ storage;

(f), select a safe and suitable CO ₂ storage place for the newly drilled CO ₂ injection well 1 and CO ₂ monitoring well 2, and run the metal casing 3 and the first downhole monitoring armored optical cable 5 synchronously and slowly to complete the drilling The CO ₂ injection well 1 and the CO ₂ monitoring well 2 are in the wellbore;

(g), at the wellhead of _CO2 injection well 1 and _CO2 monitoring well 2, install the first annular metal clip 18 at the junction of the two metal casings 3 to fix and protect the first downhole monitoring armored optical cable (5) will not be rotationally displaced and/or damaged during casing running;

(h), use a high-pressure pump truck to pump cement slurry to the bottom of CO ₂ injection well 1 and CO ₂ monitoring well 2, so that the cement slurry is returned from the bottom of the hole along the annulus between the outer wall of the metal casing 3 and the borehole. At the wellhead, after the cement slurry is consolidated, the metal casing 3, the first downhole monitoring armored optical cable 5 and the formation rock are permanently fixed together;

(i), put the CO ₂ injection pipe 4 and the second downhole monitoring armored optical cable 6 into the metal casing 3 well after the cementing and completion of the CO ₂ injection well 1 synchronously and slowly;

(j), at the wellhead of the _CO2 injection well 1, install the second annular metal clip 19 on the _CO2 injection pipe 4 according to the same spacing, and fix and protect the second downhole monitoring armored optical cable 6 under the _CO2 injection pipe 4 will not be rotated and/or damaged during installation;

(k), at the wellhead of _CO2 injection well 1 and _CO2 monitoring well 2, connect the armored spiral optical cable 12 or armored distributed three-component seismic signal sensing cable 13 in the first downhole monitoring armored optical cable 5 to the The DAS signal input end of the composite modulation and demodulation instrument 15 connects the single multimode optical fiber 22 in the first downhole monitoring armored optical cable 5 or the two multimode optical fibers 22 whose tail ends have been U-shaped fusion spliced to the composite modulation and demodulation instrument The DTS signal single-ended input terminal or double-ended input terminal of 15 is connected to the sensitive optical cable 23 of the first downhole monitoring the strain/stress in the armored optical cable 5 to the DSS signal input terminal of the composite modulation and demodulation instrument 15;

(1), at the wellhead of CO ₂ monitoring well 2, connect the single-mode optical fiber 21 in the second downhole monitoring armored optical cable 6 to the DAS signal input end of the composite modulation and demodulation instrument 15, and connect the second downhole monitoring armored optical cable 6 The single multimode optical fiber 22 or the two multimode optical fibers 22 whose tail ends have been spliced in a U-shape are connected to the single-ended or double-ended input of the DTS signal of the composite modulation and demodulation instrument 15;

(m), connect the optical fibers of the first downhole monitoring armored optical cable 5 and the second downhole monitoring armored optical cable 6 to the first downhole quasi-distributed pressure sensor array 9 and the second downhole quasi-distributed pressure sensor array 10 respectively. The DPS signal input end of the composite modulation and demodulation instrument 15;

(n), at the depth of the CO ₂ monitoring well 2 close to the CO ₂ injection horizon, place the downhole three-component detector array 7 and/or other types of monitoring instruments 8, and place each downhole three-component detector array 7 on the The first-stage three-component detector is pushed tightly against the inner wall of the metal casing 3 or the well wall, and the armored optoelectronic composite cable connecting the downhole three-component fiber optic detector array 7 is connected to the DAS of the composite modulation and demodulation instrument 15 near the wellhead. signal input terminal;

(o) Connect the armored helical optical cable 12 or armored distributed three-component seismic signal sensing cable 13 buried on the ground to the DAS signal input end of the composite modulation and demodulation instrument 15, or connect the ground-laid wired ground three-component detection The device 11 is connected to the ground seismic data acquisition instrument;

(p), during the normal operation of CO ₂ storage, that is, CO ₂ injection and storage, through the composite modulation and demodulation instrument 15 and the ground three-component geophone 11 or the armored helical optical cable 12 or the armored distributed three-component seismic The signal sensing optical cable 13 and the first downhole monitoring armored optical cable 5 and the second downhole monitoring armored optical cable 6 and the downhole three-component geophone array 7 continuously and synchronously carry out the combined microseismic monitoring on the surface and in the well, and continuously monitor the _CO injection. Well 1 and _CO2 monitoring metal casing 3 outside the first downhole monitoring armored optical cable 5 and _CO2 injection pipe 4 outside the second downhole monitoring the DAS and DTS signals inside the armored optical cable 6, while continuously monitoring and measuring metal The pressure signals of the first downhole quasi-distributed pressure sensor array 9 and the second downhole quasi-distributed pressure sensor array 10 connected in series outside the casing 3 and the outside of the CO ₂ injection pipe 4;

(q) During the normal production operation of CO ₂ sequestration, that is, during the CO ₂ injection pipe 4 or sequestration, the output of the sensitive optical cable 23 in the first downhole monitoring armored optical cable 5 outside the metal casing 3 is continuously monitored and measured by the composite modulation and demodulation instrument 15 DSS signal,

(r), modulate and demodulate the DAS signal, DTS signal, DSS signal and optical fiber pressure DPS signal continuously measured by the composite modulation and demodulation instrument 15, and convert the DAS data, DTS data, DSS data and PS data into all _CO monitoring The distribution data of the noise intensity, temperature, stress/strain and pressure change of each pressure sensor position in the whole section of Well 2;

(s), modulate and demodulate the DAS signals in all ground and monitoring wells continuously measured by the composite modulation and demodulation instrument 15, convert the DAS data into the underground microseismic data recorded by the ground and monitoring wells, and process _CO2 monitoring wells in real time Microseismic data recorded by the downhole three-component geophone array 7 in 2;

(t) According to the monitored and measured downhole noise, temperature and pressure data of _CO2 injection well 1 and _CO2 monitoring well 2, the multi-parameter comprehensive inversion method is used to calculate the CO2 in the first section of each _CO2 injection well. _2. Gas flow and its changes, so as to realize the long-term real-time dynamic monitoring of the process of CO ₂ injection and storage and the change of CO ₂ injection;

(u) According to the monitored and measured subsurface stress (strain) data of the metal casing 3 of the CO ₂ injection well 1 and the CO ₂ monitoring well 2, the real-time online analysis finds the parts or well sections where casing damage may occur, Take timely measures to repair or plug the casing damage to prevent the leakage of high-pressure _CO2 gas injected and stored underground to the surface along the wall of the _CO2 injection well 1 or _CO2 monitoring well 2 where the casing damage occurs to the surface. ACCIDENT;

(v), according to the first downhole monitoring in the ground three-component geophone 11, the embedded armored helical optical cable 12 or the armored distributed three-component seismic signal sensing cable 13 and the CO2 injection well 1 and the CO2 monitoring well 22 Armored optical cable 5 or second downhole monitoring armored optical cable 6 or downhole three-component geophone array 7 real-time monitoring and recording of the energy magnitude and time-varying spatial distribution of underground micro-seismic events, online real-time identification of normal CO ₂ storage Whether the underground large and small faults are induced and activated during _CO2 injection or storage, whether there are small faults induced and activated by high-pressure CO2 gas on the sealing caprock of the anticline structure for underground CO2 injection and storage, and whether the activated small faults will destroy CO2 The integrity of the sealing caprock in the injection and storage area, whether there will be a major safety hazard or accident that the high-pressure CO2 gas injected and stored underground leaks to the ground along the activated small faults on the sealing caprock;

(w), make full use of the ground three-component geophone 11 or the embedded armored helical optical cable 12 or the armored distributed three-component seismic signal sensing cable 13 and all the _CO2 injection wells 1 and CO2 in the underground injection and storage area ₂ Monitoring well 2, the first downhole monitoring armored optical cable 5, the second downhole monitoring armored optical cable 6, and the downhole three-component detector array 7 laid out in the monitoring well, which are arranged inside and outside the metal casing 3 and the _CO2 injection pipe 4, real-time Online monitoring of all downhole noise, temperature, pressure, stress/strain changes and distribution characteristics of micro-seismic events underground for CO ₂ injection and storage, intelligent and comprehensive analysis and evaluation of all parameters and information of real-time online monitoring The various potential risks or accidents in the safe and stable operation of the CO ₂ injection and sealing area are classified and classified, and early warning signals and information of potential high-pressure CO ₂ gas leakage accidents are released in a timely manner, so as to ensure the long-term stable and safe operation of the CO ₂ injection and storage area;

(x) Re-excitation of full-wavefield sources 14 at all sources 14 on the ground every 3 months or 6 months, ground three-component geophones 11, buried armored helical optical cables 12 or armored distributed The three-component seismic signal sensing cable 13 and the armored helical optical cable 12 outside the downhole casing or the armored distributed three-component seismic signal sensing cable 13 and the underground three-component geophone array 7 perform synchronously and jointly acquire the three-dimensional three-component time shift Seismic data in surface wells;

(y) Perform amplitude-maintained high-precision migration imaging processing on the three-dimensional three-component time-shifted surface well seismic data jointly collected by the well and ground, and extract various seismic attributes of the processed data with preserved amplitude and high-precision migration imaging. The time-lapse change of the distribution range of the attribute data volume, to understand and monitor the migration and distribution range of the high-pressure _CO gas injected into the underground reservoir in the anticline structural reservoir, such as the compressional wave velocity, shear wave velocity, compressional wave Impedance, shear wave impedance, Poisson's ratio, longitudinal wave velocity ratio, shear wave velocity ratio, longitudinal wave amplitude ratio, shear wave amplitude ratio, longitudinal wave impedance ratio, shear wave impedance ratio, longitudinal wave Q value ratio, shear wave Q value ratio, etc. CO ₂ gas has migrated to areas or formations other than the anticline structural reservoir. It is necessary to release early warning signals and information of potential high-pressure CO ₂ gas leakage accident risks in time to ensure long-term stable and safe operation of CO ₂ injection and storage areas.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple Modifications, equivalent replacements and improvements, etc., still fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. CO based on optical fiber sensing technology ₂ The site selection and safety monitoring system for the sealed storage place is characterized by comprising CO ₂ Injection well (1), CO ₂ The monitoring well (2) and the metal sleeve (3), wherein the metal sleeve (3) is arranged on the CO ₂ Injection well (1) and CO ₂ In the monitoring well (2), the CO ₂ The injection well (1) also comprises CO ₂ Injection pipe (4), CO ₂ The injection pipe (4) is arranged in the metal sleeve (3);

CO ₂ injection well (1) and CO ₂ A first underground monitoring armored optical cable (5) and CO are fixed on the outer side of the metal sleeve (3) of the monitoring well (2) ₂ CO injection into well (1) ₂ A second underground monitoring armored optical cable (6) is fixed on the outer side of the injection pipe (4), and the CO is ₂ An underground three-component detector array (7) and/or other types of monitoring instruments (8) are/is further distributed in the metal casing (3) of the monitoring well (2);

a first underground quasi-distributed pressure sensor array (9) is fixed on the outer side of the metal sleeve (3), and CO ₂ A second underground quasi-distributed pressure sensor array (10) is fixed on the outer side of the injection pipe (4);

the system also comprises a wired or wireless node type ground three-component detector (11) which is arranged on the ground in a three-dimensional mode, or an embedded armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) and a seismic source (14) which is arranged on the ground in a three-dimensional mode;

also comprises placing in CO ₂ A composite modulation and demodulation instrument (15) near the wellhead of the monitoring well (2);

the composite modulation and demodulation instrument (15) comprises a three-component distributed optical fiber acoustic wave sensing DAS, a distributed optical fiber temperature sensing DTS, a distributed optical fiber strain/stress sensing DSS and a quasi-distributed optical fiber pressure sensing DPS; the composite modulation and demodulation instrument (15) is respectively connected with the embedded armored spiral optical cable (12) or the armored distributed three-component seismic signal sensing optical cable (13), the first underground monitoring armored optical cable (5) and the second underground monitoring armored optical cable (6).

2. CO based on fiber optic sensing technology according to claim 1 ₂ The location-sealed and safety monitoring system is characterized in that the first underground monitoring armored optical cable (5) and the second underground monitoring armored optical cable (6) are both multi-parameter armored optical cables.

3. CO based on fiber optic sensing technology according to claim 1 ₂ The site selection and safety monitoring system for the sealed storage is characterized in that a armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) is arranged in the first underground monitoring armored optical cable (5), at least more than two high-temperature-resistant and hydrogen-loss-resistant single-mode optical fibers (21) and more than two high-temperature-resistant and hydrogen-loss-resistant multimode optical fibers (22) are arranged in the armored optical cable, a high-temperature-resistant high-strength composite material is injected or extruded into a cylindrical shape and tightly wrapped outside one single-mode optical fiber (21) to form a strain/stress sensitive optical cable (23), a first continuous stainless steel thin tube (24) is tightly wrapped outside the sensitive optical cable (23), the first continuous stainless steel thin tube (24) is respectively wrapped outside the other single-mode optical fibers (21) and the multimode optical fibers (22), and high-temperature-resistant optical fiber paste is filled in the wrapped first continuous stainless steel thin tube (24), the outermost side of the first underground monitoring armored optical cable (5) is a second continuous stainless steel thin tube (25) tightly wrapped, and the tail end of each single-mode optical fiber (21) is knotted orA light extinction device (26) is provided to prevent laser light incident from the tip of the single mode optical fibre (21) from reflecting from the tail end back into the tip of the fibre.

4. CO based on fiber optic sensing technology according to claim 1 ₂ The site selection and safety monitoring system for the sealed storage site is characterized in that at least more than two high-temperature-resistant and hydrogen-loss-resistant single-mode optical fibers (21) and more than two high-temperature-resistant and hydrogen-loss-resistant multimode optical fibers (22) are arranged in the second underground monitoring armored optical cable (6), the single-mode optical fibers (21) and the multimode optical fibers (22) are wrapped in the same first continuous stainless steel thin tube (24), high-temperature-resistant optical fiber paste is filled in the first continuous stainless steel thin tube (24), wherein the tail ends of two multimode optical fibers (22) are welded together, the welding position is fixed and protected by a U-shaped piece, a second continuous stainless steel thin pipe (25) is tightly wrapped outside the first continuous stainless steel thin pipe (24), the tail ends of all the single-mode optical fibers (21) are respectively knotted or provided with an extinction device (26) for preventing laser incident from the top ends of the single-mode optical fibers (21) from reflecting back to the top ends of the optical fibers from the tail ends.

5. CO based on fiber optic sensing technology according to claim 1 ₂ The system for location selection and safety monitoring of the sequestration site is characterized in that the first underground quasi-distributed pressure sensor array (9) and the second underground quasi-distributed pressure sensor array (10) are fiber optic pressure sensors of a Fabry-Perot cavity, or grating pressure sensors, or piezoelectric crystal pressure sensors;

the first underground quasi-distributed pressure sensor array (9) is connected in series at equal intervals sequentially through a first underground monitoring armored cable (5);

the second underground quasi-distributed pressure sensor array (10) is sequentially connected in series through a second underground monitoring armored optical cable (6) at equal intervals.

6. CO based on fiber optic sensing technology according to claim 1 ₂ The site selection and safety monitoring system for the sealed storage site is characterized in that: the armored distributed three-component seismic signal sensing optical cable (13) comprises a square high-temperature-resistant elastomer (16),4 high temperature resistant anti hydrogen loss single mode fiber (21) have been laid to elastomer (16) four sides, and elastomer center inlays and has a high temperature resistant anti hydrogen loss single mode fiber (21), and the seismic signal sensing optical cable of having laid single mode fiber (21) closely wraps up outward has the anticorrosive high strength composite material protective sheath of ring shape high temperature resistant (17), and the stainless steel armor steel wire protection armor distribution type three-component seismic signal sensing optical cable (13) have been around to composite material protective sheath (17) outside.

7. CO based on fiber optic sensing technology according to claim 1 ₂ The site selection and safety monitoring system for the sealed storage site is characterized by further comprising a first annular metal clip (18), wherein the first annular metal clip (18) is fixedly arranged at the boot of the metal sleeve (3); the device also comprises a second annular metal clip (19), wherein the second annular metal clip (19) is installed and fixed on the CO at equal intervals ₂ Outside the injection pipe (4).

8. CO based on fiber optic sensing technology according to claim 1 ₂ The system for location selection and safety monitoring of the sealed-up location is characterized in that the underground three-component detector array (7) and the ground three-component detector (11) are one of a three-component electromagnetic detector, a three-component piezoelectric detector, a three-component acceleration detector, a three-component MEMS detector, a three-component digital detector and a three-component optical fiber detector.

9. CO based on fiber optic sensing technology according to claim 1 ₂ The system for site selection and safety monitoring of the sealed-up sites is characterized in that the seismic source (14) which is distributed in three dimensions on the ground is one of a longitudinal wave controllable seismic source, a transverse wave controllable seismic source, a directional well gun seismic source, an air explosion longitudinal wave seismic source, an air explosion transverse wave seismic source, an electric spark seismic source, an air gun seismic source, a heavy hammer seismic source and a fixed eccentric wheel seismic source.

10. CO based on optical fiber sensing technology ₂ The method for site selection and safety monitoring of the sealed site is characterized by comprising the following steps:

(a) according to the geological structure form of the regionAnd features, preliminary confirmation of CO ₂ A candidate location for a sequestration site;

(b) in CO ₂ Laying a ground three-component detector (11) or embedding an armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) on the ground of a candidate place of the sealed area according to a pre-designed three-dimensional measuring network;

(c) in CO ₂ Measuring and marking the position of a seismic source (14) on the ground of a candidate place of the sequestration site according to a pre-designed three-dimensional measuring net;

(d) sequentially exciting a longitudinal wave seismic source signal and two orthogonal transverse wave seismic source signals of a full wave field at the position of each designed seismic source (14) according to a three-dimensional three-component seismic data acquisition design, and acquiring three-dimensional three-component ground seismic data by using a ground three-component detector (11), or an armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13), and synchronously and jointly acquiring three-dimensional three-component ground borehole seismic data by using an armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) outside a metal sleeve (3) and an underground three-component detector array (7);

(e) carrying out high-precision amplitude-preserving tectonic migration imaging processing and multiple amplitude-preserving processing seismic data attribute extraction by using ground three-dimensional three-component seismic data or ground well-in-well seismic data jointly acquired by three-dimensional three-component ground, selecting safe and appropriate CO (carbon monoxide) by using high-precision amplitude-preserving tectonic migration imaging and multiple amplitude-preserving processing seismic data attributes ₂ Sealing a place;

(f) in a safe and suitable CO ₂ Sequestration of freshly drilled CO ₂ Injection well (1) and CO ₂ In the monitoring well (2), the metal sleeve (3) and the first underground monitoring armored optical cable (5) are synchronously and slowly put into the drilled CO ₂ Injection well (1) and CO ₂ Monitoring the inside of the well bore of the well (2);

(g) in CO ₂ Injection well (1) and CO ₂ The first annular metal clip (18) is arranged at the joint of the two metal sleeves (3) at the wellhead of the monitoring well (2) to fix and protect the first underground monitoring armored cable (5) from rotating and moving and/or being damaged in the casing running process;

(h) using high pressure pump truck to CO ₂ Injection well (1) and CO ₂ Pumping cement slurry into the bottom of the monitoring well (2), so that the cement slurry returns to the wellhead from the bottom of the well along an annular area between the outer wall of the metal casing (3) and the drilled hole, and permanently fixing the metal casing (3), the first underground monitoring armored optical cable (5) and formation rock together after the cement slurry is solidified;

(i) CO (carbon dioxide) ₂ CO is synchronously and slowly put into the injection pipe (4) and the second underground monitoring armored optical cable (6) ₂ Injecting the well (1) into a metal casing (3) after well cementation and completion;

(j) in CO ₂ The second annular metal clip (19) is arranged on the CO at the wellhead of the injection well (1) according to the same interval ₂ A second underground monitoring armored cable (6) is fixed and protected on the injection pipe (4) and CO is arranged below ₂ The injection pipe (4) cannot rotate and/or be damaged in the installation process;

(k) in CO ₂ Injection well (1) and CO ₂ At the wellhead of the monitoring well (2), an armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) in a first underground monitoring armored optical cable (5) is connected to the DAS signal input end of a composite modulation and demodulation instrument (15), a single multimode optical fiber (22) or two multimode optical fibers (22) with U-shaped welded tail ends in the first underground monitoring armored optical cable (5) are connected to the single-end input end or the double-end input end of a DTS signal of the composite modulation and demodulation instrument (15), and a strain/stress sensitive optical cable (23) in the first underground monitoring armored optical cable (5) is connected to the DSS signal input end of the composite modulation and demodulation instrument (15);

(l) In CO ₂ A single mode fiber (21) in a second underground monitoring armored optical cable (6) is connected to the DAS signal input end of a composite modulation and demodulation instrument (15) at the wellhead of the monitoring well (2), and a single multimode fiber (22) or two multimode fibers (22) with U-shaped welded tail ends in the second underground monitoring armored optical cable (6) are connected to the DTS signal single-end input end or double-end input end of the composite modulation and demodulation instrument (15);

(m) respectively connecting optical fibers, which are connected with a first underground quasi-distributed pressure sensor array (9) and a second underground quasi-distributed pressure sensor array (10), in the first underground monitoring armored optical cable (5) and the second underground monitoring armored optical cable (6) to a DPS signal input end of a composite modulation and demodulation instrument (15);

(n) in CO ₂ Close to CO in the monitoring well (2) ₂ The depth of the injection horizon is provided with a down-hole three-component detector array (7) and/or other types of monitoring instruments (8), each level of three-component detectors on the down-hole three-component detector array (7) is tightly pushed against the inner wall of the metal casing (3) or the well wall, and CO is added ₂ The underground three-component detector array (7) is connected to the DAS signal input end of the composite modulation and demodulation instrument (15) near the wellhead of the monitoring well (2);

(o), connecting an armored spiral optical cable (12) embedded on the ground or an armored distributed three-component seismic signal sensing optical cable (13) to the DAS signal input end of a composite modulation and demodulation instrument (15), or connecting a wired ground three-component detector (11) distributed on the ground to a ground seismic data acquisition instrument;

(p) in CO ₂ CO injection during normal operation of the sequestration system ₂ And during the sealing period, continuously and synchronously carrying out the micro-seismic monitoring of the combination of the ground and the well and simultaneously continuously monitoring CO through a composite modulation and demodulation instrument (15), a ground three-component wave detector (11) or an armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) connected with the composite modulation and demodulation instrument, a first underground monitoring armored optical cable (5), a second underground monitoring armored optical cable (6) and an underground three-component wave detector array (7) ₂ A first underground monitoring armored optical cable (5) and CO outside a metal sleeve (3) of an injection well (1) and a monitoring well (2) ₂ The outside of the injection pipe (4) is used for second underground monitoring DAS and DTS signals in the armored optical cable (6), and simultaneously continuously monitoring and measuring the outside of the metal sleeve (3) and CO ₂ A first underground quasi-distributed pressure sensor array (9) and a second underground quasi-distributed pressure sensor array (10) which are connected in series outside the injection pipe (4) are used for receiving pressure signals;

(q) in CO ₂ Sequestration of normal production operation namely CO ₂ During the period of injecting the pipe or sealing, a composite modulation and demodulation instrument (15) is used for continuously monitoring and measuring DSS signals output by a sensitive optical cable (23) in a first underground monitoring armored optical cable (5) outside the metal sleeve (3);

(r) Modulator-demodulator for DAS, DTS, DSS and DPS signals continuously measured by the Modem (15), and converting DAS, DTS, DSS and DPS data into all CO ₂ Monitoring the noise intensity, temperature, stress/strain and pressure change distribution data of each pressure sensor position of the whole well section of the well (2);

(s) the DAS signals in all the ground and monitoring wells continuously measured by the composite modulation-demodulation instrument (15) are modulated and demodulated, DAS data are converted into underground micro-seismic data recorded by the ground and the monitoring wells, and CO is processed in real time ₂ Microseismic data recorded by an underground three-component detector array (7) in a monitoring well (2);

(t) according to the monitored and measured CO ₂ Injection well (1) and CO ₂ Monitoring the underground noise, temperature and pressure data of the well (2), and calculating each underground CO by utilizing a multi-parameter comprehensive inversion method ₂ CO injection into the wellbore section ₂ Gas flow and variations thereof;

(u) CO based on monitoring and measurement ₂ Injection well (1) and CO ₂ Monitoring underground stress (strain) data of the whole well section of the metal casing (3) of the well (2), and carrying out real-time online analysis to find a part or a well section possibly damaged by casing;

(v) according to the three-component geophone (11) on the ground, an embedded armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) and CO ₂ Injection well (1) and CO ₂ A first underground monitoring armored optical cable (5) or a second underground monitoring armored optical cable (6) in a monitoring well (2) or a three-component detector array (7) in the well monitors the energy of the underground micro-seismic event recorded in real time and the space distribution rule changing along with time;

(w) comprehensively and fully utilizing a ground three-component detector (11) or an embedded armored spiral optical cable (12) or an armored distributed three-component seismic signal sensing optical cable (13) and all CO in the underground injection and sealing area ₂ Injection well (1) and CO ₂ Monitoring well (2), metal casing (3) and CO ₂ A first underground monitoring armored cable (5) and a second underground monitoring armored cable (6) which are arranged outside the injection pipe (4)And a downhole three-component detector array (7) arranged in the monitoring well is used for monitoring the changes of noise, temperature, pressure, stress/strain and CO of all the downhole in real time on line ₂ The distribution characteristics of the micro-seismic events injected and sequestered into the subsurface;

(x) Re-exciting the full wavefield seismic sources at the positions of all the seismic sources (14) on the ground every 3 months or 6 months, and synchronously and jointly acquiring three-dimensional three-component time-shifting ground borehole seismic data by using the ground three-component detector (11), the embedded armored spiral optical cable (12) or the armored distributed three-component seismic signal sensing optical cable (13), the first underground monitoring armored optical cable (5), the second underground monitoring armored optical cable (6) and the underground three-component detector array (7);

(y) carrying out amplitude-preserving high-precision migration imaging processing on the well-ground combined three-dimensional three-component time-lapse ground well seismic data, extracting multiple three-dimensional seismic attributes of the amplitude-preserving high-precision migration imaging processing data, and knowing and monitoring high-pressure CO injected into the underground reservoir according to time-lapse change of distribution range of multiple three-dimensional seismic attribute data ₂ Migration and distribution range of gas in the anticline formation reservoir varies with time.

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