CN218324841U

CN218324841U - Underground temperature and pressure monitoring system based on sapphire optical fiber sensor

Info

Publication number: CN218324841U
Application number: CN202220680496.1U
Authority: CN
Inventors: 王锦兵; 张瀛馨; 尹华港
Original assignee: Beijing Haorui Technology Co ltd
Current assignee: Beijing Haorui Technology Co ltd
Priority date: 2022-03-25
Filing date: 2022-03-25
Publication date: 2023-01-17
Anticipated expiration: 2032-03-25

Abstract

The utility model discloses a temperature pressure monitoring system in pit based on sapphire optical fiber sensor: the sensor comprises a sapphire sensor (1), a sensor protector (2), an armored optical cable (5), a wellhead blowout preventer (15) and a demodulator (17), wherein the sapphire sensor (1) is connected with the armored optical cable (5) through the sensor protector (2), the armored optical cable (5) extends and is connected to the wellhead blowout preventer (15), and the demodulator (17) is connected with the armored optical cable (5) through a buried optical cable (16) and the wellhead blowout preventer (15).

Description

Underground temperature and pressure monitoring system based on sapphire optical fiber sensor

Technical Field

The utility model relates to an oil exploration technical field, more specifically relate to a temperature pressure monitoring system in pit based on sapphire optical fiber sensor.

Background

In the process of oil exploitation, underground temperature and pressure are indispensable measurement parameters, and accurate underground temperature and pressure measurement plays an important role in oil well monitoring and the like. After the oil field is put into development, the reservoir pressure is continuously reduced along with the increase of the exploitation time, the underground crude oil is greatly degassed, the viscosity is increased, the yield of the oil well is greatly reduced, and even the blowout and production stop can be realized. In order to make up for the underground deficit caused by the production of crude oil, maintain or improve the pressure of an oil layer and realize high and stable production of an oil field, a water injection well is used for injecting water/gas into the oil layer so as to supplement and maintain the pressure of the oil layer. However, these operations must be undertaken after a thorough understanding of the downhole conditions.

That is, during the development of an oil field, it is necessary to know the details of the well fluid retention and status during production or flooding, which is a well log where reliability and accuracy are critical.

For the current monitoring system for downhole temperature and pressure, the measurement of downhole temperature and pressure parameters mainly depends on capillary pressure measurement and electronic sensing technology. However, the electronic sensor has the problems of short service life, easy electric ignition, annual ground calibration and the like, so that the electronic sensor can only be applied to conventional logging and short-term logging operations and cannot adapt to the requirement of long-term underground monitoring of a gas storage. For the way of measuring the pressure by the capillary tube, it can only measure the pressure value but not the temperature value, which is the biggest disadvantage. In addition, the capillary pressure measuring system needs to continuously supplement nitrogen in the process of downhole operation to ensure that the capillary is filled with nitrogen, so that the operation time and the corresponding operation cost are greatly increased; the density of nitrogen in a capillary nitrogen barrel and in the capillary is changed due to underground temperature change, the ground temperature is corrected to adjust the ground in time to supplement the nitrogen, the temperature is detected by mostly adopting hysteretic ground temperature compensation and adding a thermocouple, and the complex structure is not favorable for the safe and stable operation of equipment; whether the installation is normal or not is judged only by observing the back pressure in the installation process, and if the damage occurs at a deeper position, the judgment is difficult.

The fiber optic sensors transmit information sensed downhole to a surface receiving device through a fiber optic cable, which is typically provided with a protective armor for protecting the cable from damage during use. However, armored fiber optic cables need to be run downhole through certain components, such as packers, and therefore need to be severed. After being cut, pass through the respective parts, after which the armored cable needs to be spliced. However, since the downhole environment is harsh and the cable is typically made of glass, quartz, etc., which is inherently brittle and fragile, the splice point of the armored cable is typically fragile and requires special protection. However, no particularly effective measures are available in the prior art. And, once the downhole armored cable is broken downhole, the downhole pressure will be transmitted to the surface through the inside of the downhole armored cable, resulting in downhole fluid leakage and blowout.

Accordingly, there is a need for new devices and techniques to at least partially overcome the problems with the prior art.

SUMMERY OF THE UTILITY MODEL

Research has shown that fiber optic sensors have advantages such as being insensitive to electromagnetic interference and capable of withstanding extreme conditions including high temperatures, high pressures and strong shock and vibration, allowing high precision measurements of wellbore and wellsite environmental parameters while having distributed measurement capabilities that allow for the measurement of the spatial distribution of certain parameters, giving profile information. In addition, the optical fiber sensor has small cross-sectional area and short profile, and only needs to occupy extremely small space in a shaft.

More specifically, the sapphire optical fiber sensor has the characteristics of long service life, long sensing distance, high temperature resistance, multiple measuring points, good expandability, strong shock resistance, interference resistance, small potential safety hazard and the like.

Compared with an electronic sensor, the sapphire optical fiber sensor has the service life obviously prolonged, the service life of a temperature and pressure sensor of a general sapphire optical fiber sensor can reach 10-15 years, and the average service life of the electronic sensor is only 1-3 years. Often, the sensors fail before the well has been depleted, requiring replacement of new sensing equipment if continued temperature and pressure data is desired. The old equipment is taken out in the oil and gas well of hundreds of meters to thousands of meters deep and new equipment is installed again, the workload and the cost are huge, the production is influenced, the risk of accidents is increased due to the increased construction times, and the cost for purchasing the new equipment is added, so that the electronic sensor is not as good as a sapphire optical fiber sensor in the aspect of overall economy in a longitudinal view.

Sapphire sensors have a longer transmission distance than electronic sensors, which typically have a maximum sensing distance of less than 5Km due to the relatively high attenuation of the signal in the cable. For a deep well with the well depth exceeding 5Km, a complex active device has to be additionally arranged for signal amplification so as to ensure the signal quality. This limits the use of electronic sensors in deep wells, particularly in oil and gas wells, which are widespread today. Because the signal attenuation of the optical signal in the optical cable is very small, the effective sensing distance of the optical sensor can reach 20km, and the optical sensor is suitable for sensing deep wells and greatly exceeds the application range of electronic sensing.

For the electronic sensor, because the working temperature of the electronic sensor is limited by the working temperature of the electronic element, the working temperature of the electronic sensor is generally lower than 175 ℃, the electronic sensor cannot be used for a long time for a high-temperature oil-gas well with the temperature higher than 175 ℃, the failure probability of the electronic sensor is higher when the electronic sensor is used for a long time at high temperature, so the high temperature is a bottleneck for the electronic sensor, and the quartz sensor is also the same problem. For the sapphire optical fiber sensor, the part of the sensor under the well is used for a sapphire Fabry-Perot cavity optical device integrating temperature measurement and pressure measurement, and the device has excellent performance under the high-temperature condition. Therefore, for the high-temperature oil well widely existing today, the performance of the sapphire sensing equipment which can normally work at high temperature for a long time greatly exceeds that of an electronic sensor and a quartz sensor, and the sapphire sensing equipment is more suitable for the high-temperature oil well.

The electronic sensors typically have no more than 10 measurement points, otherwise the system becomes complex and bulky and installation becomes difficult. For a common single-point electronic temperature and pressure sensor, 4 copper wires are needed for transmitting sensor signals; and the sapphire optical fiber sensor also only needs one single-mode optical fiber for completing the transmission of the temperature and pressure signals. In addition, the optical cable can be used as an expandable technical platform to simultaneously complete the measurement of temperature and pressure single-point measurement, distributed temperature measurement, multi-directional flow, distributed sound waves and the like, so that the aim of one cable with multiple purposes is fulfilled, and the design flexibility is improved.

The sensing head of the sapphire sensor is small, so that the impact generated during vibration is relatively small, and the anti-seismic performance of the sapphire sensor is excellent. The electronic sensor is provided with a large number of electronic components, and the volume and the weight of core components are larger than those of the sapphire sensor, so that the components can bear larger impact in the vibration and impact process, and the optical fiber sensor is more superior in anti-seismic indexes. Since vibration is inevitable during transportation, installation and downhole use of the sensor, it is an index of whether the sensor performance is excellent.

Electronic sensors are susceptible to electromagnetic interference due to the use of electronics and circuitry. While sapphire sensors are completely immune to electromagnetic interference. In addition, the electronic sensors working in the underground flammable and explosive environment are active charged equipment, measures such as improving the protection level and designing a safer circuit can be taken, but the possibility of electric sparking caused by equipment damage always exists, and all active devices of the sapphire sensors are all in equipment rooms at the wellhead, so that the sapphire sensors are completely free of the risk of electric sparking.

Therefore, according to the utility model discloses an aspect provides a temperature pressure monitoring system in pit based on sapphire optical fiber sensor, including sapphire sensor (1), sensor protector (2), armor optical cable (5), well head blowout preventer (15) and demodulation appearance (17), sapphire sensor (1) passes through sensor protector (2) and is connected with armor optical cable (5), armor optical cable (5) extend and connect to well head blowout preventer (15), demodulation appearance (17) are through burying optical cable (16) and well head blowout preventer (15) and are connected armor optical cable (5);

wherein the sapphire sensor (1) comprises a sapphire sensor unit (1-0), the sapphire sensor unit (1-0) adopts sapphire to form a Fabry-Perot cavity structure, and comprises a sapphire pressure-resistant diaphragm (1-0-1), a sapphire pressure-resistant cavity (1-0-2), a sapphire temperature-resistant diaphragm (1-0-3), a sapphire Palo cavity main body (1-0-4), a collimator (1-0-5) and a high-temperature optical fiber (1-6) connected with the collimator (1-0-5),

the sapphire pressure-resistant diaphragm (1-0-1) and the sapphire temperature-resistant diaphragm (1-0-3) are respectively welded at two ends of the sapphire pressure-resistant cavity (1-0-2) through ceramic powder sintering, so that a pressure-sensitive cavity (1-0-6) is formed, one end of the sapphire Palo cavity main body (1-0-4) is welded on the sapphire temperature-resistant diaphragm (1-0-3) through ceramic powder sintering, and the sapphire temperature-resistant diaphragm (1-0-3) is arranged between the sapphire Palo cavity main body (1-0-4) and the sapphire pressure-resistant cavity (1-0-2); collimators (1-0-5) are fixed in the interior chamber of the sapphire parlo chamber body (1-0-4).

According to an embodiment of the utility model, the sapphire sensor (1) further comprises a sapphire sensor main body (1-2) and a connecting piece,

the sapphire sensor comprises a sapphire sensor body (1-2) and a pressure inlet end, wherein the sapphire sensor unit (1-0) is arranged in an inner cavity of the sapphire sensor body (1-2), a sapphire pressure-resistant diaphragm (1-0-1) faces the pressure inlet end, and the sapphire Palo cavity body (1-0-4) is hermetically fixed in the inner cavity on one side of the outlet end;

the high-temperature optical fiber (1-6) passes through the outlet end and penetrates through the connecting piece, the connecting piece comprises a connecting shaft (1-5), two sensor connecting studs (1-4) and two limiting rings (1-3), the two sensor connecting studs (1-4) are respectively sleeved on the two sides of the connecting shaft (1-5), the thread directions of the two sensor connecting studs face the two sides respectively, the two ends of the connecting shaft (1-5) are connected with the two limiting rings (1-3) through threads, and one end of the connecting piece is connected with the outlet end of the sapphire sensor main body (1-2) in a sealing mode through the thread connection of one sensor connecting stud (1-4).

According to an embodiment of the present invention, the sensor protector (2) sealingly connects the other end of the connector, whereby a fusion point (5-2) at which both the high temperature optical fiber (1-6) and the optical fiber (5-1) in the armored optical cable (5) passing through the sensor protector (2) are fused can be located within the sensor protector (2) to be protected;

wherein the sensor protector (2) comprises a sensor welding spot protector front end connector (2-1) which is connected with the other end of the connecting piece in a sealing way, a sensor welding spot protector middle tube (2-2) and a first sealing connecting component,

the front end connector (2-1) of the sensor welding spot protector is connected with one end of a sensor welding spot protector intermediate pipe (2-2) in a sealing welding mode, the first sealing connecting assembly is connected with the other end of the sensor welding spot protector intermediate pipe (2-2) in a sealing mode, and a welding point (5-2) is located in the sensor welding spot protector intermediate pipe (2-2);

the first sealing connection assembly comprises a continuous joint protector tail end (2-3), a tail end sealing stud (2-7), a tail end connecting piece (2-11) and a tail end pressing stud (2-12);

the right end of the tail end (2-3) of the protector is hermetically welded and fixed at the left end of the middle pipe (2-2) of the sensor welding spot protector; a conical surface is formed at the right end of the connecting inner cavity of the tail end (2-3) of the protector;

a first shaft shoulder, a first annular groove and a second shaft shoulder are sequentially formed on the periphery of the tail end sealing stud (2-7) from right to left, and a first sealing ring (2-6), a first semicircular spacer bush (2-8) and a second sealing ring (2-10) are respectively arranged on the first shaft shoulder, the first annular groove and the second tail shaft shoulder; a first steel wire clamping ring (2-9) is arranged in the middle of the outer surface of the first semicircular spacer bush (2-8); a first flanging cutting sleeve (2-5) is arranged at the right end of the tail end sealing stud (2-7), a first metal cone sealing component (2-4) is arranged between the first flanging cutting sleeve (2-5) and the conical surface of the tail end (2-3) of the protector, and thus the connecting inner cavity of the tail end (2-3) of the protector is hermetically connected with the tail end sealing stud (2-7) through threads;

a second annular groove and a third shaft shoulder are sequentially formed in the periphery of the tail end connecting piece (2-11) from right to left, and a second semicircular spacer bush (2-13) and a third sealing ring (2-14) are respectively arranged on the second annular groove and the third shaft shoulder; a second steel wire clamping ring (2-15) is arranged in the middle of the outer surface of the second semicircular spacer bush (2-13); a second metal cone sealing assembly (2-16) is arranged between the right end of the tail end connecting piece (2-11) and the conical surface formed by the right end of the connecting inner cavity of the tail end sealing stud (2-7), so that the connecting inner cavity of the tail end sealing stud (2-7) is connected with the tail end connecting piece (2-11) in a sealing mode through threads;

the right end of a connecting inner cavity of the tail end connecting piece (2-11) is provided with a conical surface, a third metal cone sealing assembly (2-17) is arranged between the conical surface and the right end of the tail end pressing stud (2-12), and therefore the connecting inner cavity of the tail end connecting piece (2-11) is connected with the tail end pressing stud (2-12) in a sealing mode through threads.

According to the embodiment of the utility model, the downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor further comprises an armored optical cable splicing protection device (9) for hermetically connecting two sections of armored optical cables;

the armored optical cable splicing protection device (9) comprises a middle protection tube (9-2), a second sealing connection assembly and a third sealing connection assembly, wherein the two sealing connection assemblies are respectively fixed at two ends of the middle protection tube (9-2) in a sealing mode, the two sections of armored optical cables can respectively penetrate through the two sealing connection assemblies in a sealing mode and are spliced in the middle protection tube (9-2), and therefore a splicing point (9-1) is located in the middle protection tube (9-2);

wherein the second and third seal connection assemblies have the same structure as the first seal connection assembly.

According to the utility model discloses an embodiment, temperature pressure monitoring system in pit based on sapphire optical fiber sensor still includes that the sensor drags a section of thick bamboo (3) and continuous connector drags a section of thick bamboo (10), the sensor drags a section of thick bamboo (3) to set up to encapsulate sensor protector (2) and sapphire sensor (1), continuous connector drags a section of thick bamboo (10) to set up to encapsulate continuous protection device (9) that connects of armor optical cable.

According to the embodiment of the utility model, the wellhead blowout preventer (15) comprises a high-pressure pipe mounting adapter (15-1), a high-pressure hose (15-2), a connecting flange (15-3), a pressure cavity (15-7), a pressure-resistant upper flange (15-16), a pressure gauge (15-17), a first sealing assembly and a second sealing assembly;

wherein, a first through hole (151) is formed on the right side wall of the pressure cavity (15-7), a second through hole (152) is formed on the left side wall, the upper part of the pressure cavity is opened, and a pressure-resistant upper flange (15-16) is fixed on the upper part of the pressure cavity (15-7) to seal the pressure cavity (15-7); the pressure gauge (15-17) is fixed on the pressure-resistant upper flange (15-16) and used for measuring the internal pressure of the pressure cavity (15-7);

the connecting flange (15-3) is hermetically fixed on the right side wall of the pressure cavity (15-7) and is communicated with the first through hole (151); the connecting flange (15-3) is in threaded connection with the high-pressure hose (15-2), and the high-pressure hose (15-2) is in threaded connection with the high-pressure pipe mounting adapter (15-1);

the first sealing assembly is used for hermetically fixing the armored optical cable (5) which sequentially passes through the high-pressure pipe mounting adapter (15-1), the high-pressure hose (15-2), the connecting flange (15-3) and the first through hole (151) and enters the pressure cavity (15-7) on the connecting flange (15-3);

the second sealing assembly is arranged at the second through hole (152) and is used for sealing and fixing the outgoing optical fiber (15-8) connected with the armored optical cable (5) in the pressure cavity (15-7) on the left side wall.

According to the utility model discloses an embodiment, well head blowout preventer (15) still includes sets up at the left optic fibre splicing box (15-21) of pressure cavity (15-7), is provided with waterproof cable joint (15-12) on optic fibre splicing box (15-21), and the one end of buried optical cable (16) gets into in optic fibre splicing box (15-21) and is connected with drawing optic fibre (15-8) through waterproof cable joint (15-12), the other end with demodulation appearance (17) are connected.

According to the utility model discloses an embodiment, be formed with third through-hole (153) and fourth through-hole (154) on the pressure cavity (15-7) left side wall to be provided with the manual needle valve of superhigh pressure (15-20) on third through-hole (153), and seal the sclausura plug (15-13) and fix on fourth through-hole (154) through the third seal assembly.

According to an embodiment of the present invention, the protector tail end (2-3) further comprises a first detection hole (2-18) formed on the side wall for detecting the tightness between the tail end sealing stud (2-7) and the protector tail end (2-3); the tail end sealing stud (2-7) further comprises a second detection hole (2-19) formed in the side wall and used for detecting the tightness between the tail end sealing stud (2-7) and the tail end connecting piece (2-11).

According to an embodiment of the present invention, the sapphire sensor (1) further comprises a sensor pressure inlet piece (1-1) connected with the pressure inlet end of the sapphire sensor body (1-2).

The utility model discloses a temperature pressure monitoring system in pit based on sapphire optical fiber sensor, through installing sapphire sensor on the sensor drags a section of thick bamboo and follow the tubular column and go into the well in, the laser instrument in the demodulation appearance sends laser, and light signal passes through the sapphire sensor in pit of optic fibre arrival; the sapphire sensor reflects laser emitted by the laser, and when the ambient temperature and the ambient pressure change, a spectral signal reflected from the sapphire sensor also changes correspondingly; the demodulator (17) receives the spectrum reflected from the sapphire sensor; the values of temperature and pressure were obtained by analysis of the interference spectrum. The problems that detection data are inaccurate and real-time detection is not achieved are solved; and the system does not have electronic components in the oil gas well, so that the problem of short service life is solved. The underground temperature and pressure parameters are monitored in real time in the whole service life of the oil and gas well, and the underground temperature and pressure parameters are transmitted to a demodulator on the ground in real time to be displayed and stored. The real-time downhole temperature and pressure parameter data can assist production engineers and oil deposit analysts in optimizing production in real time, diagnosing faults in time and dynamically knowing the change trend of the oil deposit, and is an important decision basis for planning the oil deposit and making a production task. In addition, the underground armored optical cable splicing protection device adopts a mode of combining and sealing a plurality of components, so that the risk of damage and fracture of the splicing point caused by the stress of the optical cable near the splicing point of the optical cable can be avoided or reduced; the wellhead blowout preventer (15) can prevent the armored optical cable (5) from leaking and causing the risk of blowout when the underground fracture occurs.

Drawings

Some specific embodiments of the present invention will be described in detail hereinafter, by way of illustration and not by way of limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. The objects and features of the present invention will become more apparent in view of the following description taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic structural diagram of a downhole temperature and pressure monitoring system based on a sapphire optical fiber sensor according to an embodiment of the invention;

fig. 2 is a schematic structural diagram of a sapphire sensor unit of a sapphire sensor of a downhole temperature and pressure monitoring system based on a sapphire optical fiber sensor according to an embodiment of the present invention;

fig. 3 is a schematic view of a partial structure of a middle sapphire sensor, a sensor protector and an armored cable assembly of a downhole temperature and pressure monitoring system based on a sapphire optical fiber sensor according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a sensor protector of a downhole temperature and pressure monitoring system based on a sapphire optical fiber sensor according to an embodiment of the present invention;

fig. 5 is a schematic cross-sectional view of a sapphire sensor and sensor protector with a sensor trawl in a sapphire optical fiber sensor based downhole temperature and pressure monitoring system according to an embodiment of the present invention;

fig. 6 is a graphical representation of the pressure change results displayed by the digital pressure gauge when monitoring pressure using a sapphire sensor according to an embodiment of the present invention;

FIG. 7 is a graphical representation of the results of cavity length changes corresponding to the pressure changes shown in FIG. 6;

fig. 8 is a calibration curve diagram of the pressure and cavity length of the sapphire optical fiber sensor in the downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor according to the embodiment of the present invention;

fig. 9 is a calibration graph of temperature of a sapphire sensor and thickness of a sapphire temperature-resistant diaphragm in a sapphire optical fiber sensor-based downhole temperature and pressure monitoring system according to an embodiment of the present invention;

fig. 10 is a schematic cross-sectional structural view of a wellhead blowout preventer for armored fiber optic cables in a downhole temperature and pressure monitoring system based on sapphire fiber optic sensors according to an embodiment of the present invention;

fig. 11 is a schematic view of the overlooking structure of the wellhead blowout preventer for armored optical cable in the downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor according to the embodiment of the present invention, and

fig. 12 is a schematic structural diagram of an armored cable splicing protection device in a downhole temperature and pressure monitoring system based on a sapphire optical fiber sensor according to the embodiment of the invention.

Detailed Description

The invention can be better understood with reference to the following examples and the accompanying drawings. However, those skilled in the art will readily appreciate that the description of the embodiments is only for the purpose of illustrating the present invention and should not be taken as limiting the invention.

Fig. 1 is according to the utility model discloses embodiment's temperature pressure monitoring system's in pit based on sapphire optical fiber sensor structure schematic diagram. The downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor can be combined with the existing oil extraction device and used for monitoring parameters such as pressure, temperature and the like in the well. As shown in fig. 1, the oil and gas well body 12 is arranged in rock and soil 18, a tubing hanger 13 and a christmas tree 14 are fixedly installed at the top of the oil and gas well body 12, a tubing string 11 is installed at the bottom of the tubing hanger 13 and inside the oil and gas well body 12, and a packer 8 is installed below the tubing hanger 13 and on the tubing string 11; and a Y-TOOL device 6 is arranged below the packer 8 and on the tubular column 11. The utility model discloses a temperature pressure monitoring system in pit based on sapphire optical fiber sensor can combine on above-mentioned oil recovery device.

Specifically, the downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor of the embodiment can comprise a sapphire sensor 1, a sensor protector 2, a sensor drag cylinder 3, an armored optical cable 5, an armored optical cable splicing protection device 9, a splicer drag cylinder 10, a wellhead blowout preventer 15 and a demodulator 17; the sapphire sensor 1 is connected with an armored optical cable 5 through a sensor protector 2, the armored optical cable 5 extends through the packer 8, meanwhile, the bottom and the top of the packer 8 are provided with sealing elements 7 for sealing, and after the sealing elements pass through the packer 8, the other armored optical cable is connected. That is, after fusion by armored cable splice protector 9, it extends through tubing hanger 13 and christmas tree 14 into wellhead blowout preventer 15, and is connected to demodulator 17 by buried cable 16. The armored cable 5 may be secured to the pipe string by the cable protector 4 during downhole extension, as may the sensor pull barrel 3 and the adapter pull barrel 10.

The various components are described in greater detail below in conjunction with the figures.

Fig. 2 is according to the utility model discloses a sapphire optical fiber sensor based on sapphire optical fiber sensor's temperature pressure monitoring system's sapphire sensor unit structure sketch map in pit. Referring to fig. 2, the sapphire sensor 1 of the embodiment includes a sapphire sensor unit 1-0, wherein the sapphire sensor unit 1-0 may include a sapphire pressure-resistant diaphragm 1-0-1, a sapphire pressure-resistant chamber 1-0-2, a sapphire temperature-resistant diaphragm 1-0-3, a sapphire parlo chamber body 1-0-4, a collimator 1-0-5, and a high-temperature optical fiber 1-6 connected to the collimator 1-0-5; wherein, one side of each of the sapphire pressure-resistant diaphragm 1-0-1 and the sapphire temperature-resistant diaphragm 1-0-3 is respectively welded at two ends of the sapphire pressure-resistant cavity 1-0-2 through ceramic powder sintering, thereby forming a pressure-sensitive cavity 1-0-6. The other side of the sapphire temperature-resistant diaphragm 1-0-3 is welded at one end of the sapphire Palo cavity body 1-0-4 through ceramic powder sintering, and the collimator 1-0-5 is fixed in an inner cavity of the sapphire Palo cavity body 1-0-4. The sapphire sensor cell 1-0 having a fabry-perot cavity structure is thus formed using sapphire.

As shown, the ambient pressure P0 exerts a pressure on the sapphire sensor cell 1-0, causing the cavity length L0 of the pressure sensing cavity 1-0-6 to change. The larger the outside pressure P0 is, the shorter the cavity length L0 is; the smaller the outside pressure P0 is, the longer the cavity length L0 is; through calibration, the corresponding relationship between the external pressure P0 and the cavity length L0 can be established.

When the pressure gauge is used, the external pressure P0 can be obtained through a calibration curve by accurately detecting the cavity length L0 of the cavity. Fig. 6 is a graphical representation of the pressure change results displayed by the digital pressure gauge when monitoring pressure using a sapphire sensor according to an embodiment of the present invention; FIG. 7 is a graphical representation of the results of cavity length changes corresponding to the pressure changes shown in FIG. 6. As shown in FIGS. 6 and 7, as the ambient pressure increases, the length of the chamber length L0 of the pressure sensing chambers 1-0-6 decreases; when the external pressure is reduced, the length of the cavity length L0 of the pressure sensing cavities 1-0-6 is increased. From this the size of external pressure P and the cavity length d in fabry-perot chamber between the inversely proportional relation, can obtain pressure sensor's demarcation curve through the demarcation to pressure sensor, the result is shown as figure 8, shows the utility model discloses pressure sensor's good linear relation and accuracy.

In addition, the temperature of the surrounding environment can cause the thickness H0 of the sapphire temperature-resistant diaphragm 1-0-3 to change. The higher the temperature, the larger the thickness; the lower the temperature, the smaller the thickness; and establishing a corresponding relation between the temperature and the film thickness H0 through calibration. When the temperature-measuring device is used, the thickness H0) is accurately detected, for example, the phase difference of the reflected light of the laser incident to the first surface of the sapphire temperature-resistant diaphragm 1-0-3 and the sine wave of the reflected light passing through the diaphragm incident to the second surface is calculated, and the temperature can be obtained through a calibration curve. Fig. 9 is according to the utility model discloses sapphire optical fiber sensor based on among sapphire optical fiber sensor's the temperature of temperature pressure monitoring system in pit and the demarcation curve graph of sapphire temperature resistant diaphragm thickness, the result shows the utility model discloses temperature sensor has good linear relation and accuracy.

Fig. 3 is according to the utility model discloses a partial structure schematic diagram of sapphire optical fiber sensor based temperature and pressure monitoring system's in pit, sensor protector and armor optical cable combination. Referring to fig. 3, the sapphire sensor 1 further includes a sapphire sensor body 1-2, and a sensor pressure inlet port 1-1 and a connector respectively connected to a pressure inlet end and an outlet end of the sapphire sensor body 1-2. The sapphire sensor body 1-2 is a cylinder having an inner cavity, and includes an outlet end and a pressure inlet end (in the drawing, the right side is the pressure inlet end, and the left side is the outlet end). The sapphire sensor unit 1-0 is arranged in an inner cavity of the sapphire sensor main body 1-2, the sapphire pressure-resistant diaphragm 1-0-1 faces the pressure inlet end, and the sapphire Parlo cavity main body 1-0-4 is hermetically fixed in the inner cavity on one side of the outlet end. The sapphire perot cavity body 1-0-4 may be sealingly bonded, for example, with a high temperature resistant adhesive such as an epoxy adhesive, into the interior cavity of the sapphire sensor body 1-2 proximate the outlet port, whereby the sapphire perot cavity body 1-0-4 may be sealingly separated by the pressure inlet port and the outlet port of the sapphire sensor body 1-2.

As shown, the sensor pressure inlet piece 1-1 is connected to the pressure inlet end of the sapphire sensor body 1-2, and a passage is formed in the sensor pressure inlet piece 1-1 for guiding fluid from the external environment into the sapphire sensor body 1-2. For example, the connection end of the sensor pressure inlet port 1-1 is formed with a protrusion and the pressure inlet port is formed with a recess, and the protrusion and the recess may be engaged with each other by a screw thread or may be welded together.

Referring to fig. 3, the outlet end of the sapphire sensor body 1-2 is connected to the connector, and the high-temperature optical fiber 1-6 of the sapphire sensor unit 1-0 passes through the outlet end and passes through the connector. The connecting piece comprises a connecting shaft 1-5, two sensor connecting studs 1-4 and two limiting rings 1-3. The two sensor connecting studs 1-4 are respectively sleeved on two sides of the connecting shaft 1-5, threads are formed on the outer surfaces of the two sensor connecting studs, the thread directions face the two sides respectively, two ends of the connecting shaft 1-5 are connected with the two limiting rings 1-3 through threads, one end of the connecting piece is connected with the threads on the inner surface of the outlet end of the sapphire sensor main body 1-2 through the threads of one sensor connecting stud 1-4, and therefore the outlet end of the sapphire sensor main body 1-2 is connected. More specifically, the outlet end of the sapphire sensor body 1-2 is formed with a concave conical surface, and the connecting shaft 1-5 is formed with a corresponding convex conical surface, and the two components are in close contact under the action of the sensor connecting stud 1-4, so that sealing is realized.

Referring to fig. 3 and 4, the sensor protector 2 of an embodiment may include a sensor pad protector front end fitting 2-1, a sensor pad protector intermediate tube 2-2, and a first seal connection assembly. One end of the front end connector 2-1 of the sensor welding spot protector is hermetically connected with the other end of the connecting piece, and the connecting mode of the front end connector and the connecting piece can be the same as that of the connecting piece and the sapphire sensor main body 1-2, so the description is omitted. The other end of the front end connector 2-1 of the sensor welding spot protector is hermetically connected with the middle tube 2-2 of the sensor welding spot protector, for example, the other end can be sealed by welding. The high temperature optical fiber 1-6 can thus sealingly pass through the connector and the sensor pad protector front end fitting 2-1 and into the sensor pad protector intermediate tube 2-2.

As shown in FIG. 4, a first sealing connection assembly is hermetically connected to the other end of the sensor welding spot protector intermediate pipe 2-2, and an armored optical cable 5 passes through the first sealing connection assembly and enters the sensor welding spot protector intermediate pipe 2-2, so that the optical fiber 5-1 and the high-temperature optical fiber 1-6 are welded together in the sensor welding spot protector intermediate pipe 2-2 and protected.

Referring to fig. 4, a first seal connection assembly of an embodiment may include a splice protector tail end 2-3, a tail seal stud 2-7, a tail connector 2-11, and a tail hold down stud 2-12; the right end of the tail end 2-3 of the protector is hermetically welded and fixed at the left end of the middle tube 2-2 of the sensor welding spot protector; and the right end of the connecting inner cavity of the tail end 2-3 of the protector is provided with a conical surface.

More specifically, a convex structure is formed at the right end of the tail end 2-3 of the protector, and a matched concave structure is formed at the left end of the middle tube 2-2 of the sensor welding spot protector, so that the two are matched together, and then the right end of the tail end 2-3 of the protector can be welded and fixed at the left end of the middle tube 2-2 of the sensor welding spot protector in a sealing manner through welding. A connecting inner cavity is formed in the tail end 2-3 of the protector, the inner diameter of the connecting inner cavity is gradually reduced from left to right, threads for connecting the tail end sealing stud 2-7 are formed in the connecting inner cavity, and a conical surface is formed at the right end of the connecting inner cavity.

Threads matched with the threads in the connecting inner cavity of the tail end 2-3 of the protector are formed on the periphery of the tail end sealing stud 2-7, and a first shaft shoulder, a first ring groove and a second shaft shoulder are sequentially formed on the periphery from right to left; a first sealing ring 2-6, a first semicircular spacer bush 2-8 and a second sealing ring 2-10 are respectively arranged on the first shaft shoulder, the first ring groove and the second tail shaft shoulder, and the first semicircular spacer bush 2-8 is adjacent to the second sealing ring 2-10; a first steel wire clamping ring 2-9 is arranged in the middle of the outer surface of the first semicircular spacer bush 2-8; a first flanging cutting sleeve 2-5 is arranged at the right end of the tail end sealing stud 2-7, a first metal cone sealing component 2-4 is arranged between the first flanging cutting sleeve 2-5 and the conical surface of the tail end 2-3 of the protector, and therefore the connecting inner cavity of the tail end 2-3 of the protector is hermetically connected with the tail end sealing stud 2-7 through threads; in addition, a connecting inner cavity is formed in the tail end sealing stud 2-7, the inner diameter of the connecting inner cavity is gradually reduced from left to right, threads for connecting the tail end connecting piece 2-11 are formed in the connecting inner cavity, and a conical surface is formed at the right end of the connecting inner cavity.

The periphery of the tail end connecting piece 2-11 is provided with threads matched with the threads in the connecting inner cavity of the tail end sealing stud 2-7, a second annular groove and a third shaft shoulder are sequentially formed on the periphery from right to left, a second semicircular spacer bush 2-13 and a third sealing ring 2-14 are respectively arranged on the second annular groove and the third shaft shoulder, and the second semicircular spacer bush 2-13 is adjacent to the third sealing ring 2-14; a second steel wire clamping ring 2-15 is arranged in the middle of the outer surface of the second semicircular spacer bush 2-13; and a second metal cone sealing assembly 2-16 is arranged between the right end of the tail end connecting piece 2-11 and a conical surface formed at the right end of the connecting inner cavity of the tail end sealing stud 2-7, so that the connecting inner cavity of the tail end sealing stud 2-7 is hermetically connected with the tail end connecting piece 2-11 through threads.

A connecting inner cavity is formed in the tail end connecting piece 2-11, threads for connecting the tail end compression stud 2-12 are formed in the connecting inner cavity, a conical surface is formed at the right end of the connecting inner cavity, a third metal cone sealing assembly 2-17 is arranged between the conical surface and the right end of the tail end compression stud 2-12, threads matched with the threads in the connecting inner cavity of the tail end connecting piece 2-11 are formed on the periphery of the tail end compression stud 2-12, and therefore the connecting inner cavity of the tail end connecting piece 2-11 is connected with the tail end compression stud 2-12 in a sealing mode through the threads.

As shown in fig. 4, the positions of the inner or outer walls of the protector tail end 2-3, tail end seal stud 2-7, tail end connector 2-11 and tail end hold down stud 2-12 where the cooperating threads are formed may be shown as dashed circles.

In addition, in order to detect the tightness between the various components, a first detection hole 2-18 may be formed, for example, in the side wall of the protector tail end 2-3 for detecting the tightness between the tail end seal stud 2-7 and the protector tail end 2-3. Such as the sealing effect of the first metal cone sealing component 2-4, the first flanging ferrule 2-5 and the first sealing ring 2-6; 2-8 parts of a first semicircular spacer bush and 2-9 parts of a first steel wire clamping ring; the sealing effect of the second sealing rings 2-10 etc. Second inspection holes 2-19 may also be formed in the sidewalls of the trailing seal studs 2-7 for inspecting the seal between the trailing seal studs 2-7 and the trailing connectors 2-11. For example, the sealing effect of the second metal cone sealing assembly 2-16, the sealing effect of the second semicircular spacer 2-13, the third sealing ring 2-14 and the second wire collar 2-15, etc.

The above components are made of high temperature and high pressure resistant materials, for example, the middle protection tube 2-2, the protector tail end 2-3, the tail end sealing stud 2-7, the tail end connecting piece 2-11 and the tail end pressing stud 2-12 can be made of stainless steel materials, and the middle sealing components can also be made of metals or other materials such as carbon materials.

Fig. 5 is according to the utility model discloses a sapphire fiber sensor based downhole temperature and pressure monitoring system in has sensor to drag a sapphire sensor and sensor protector's enlarged schematic diagram of cross-section in section of 3. Referring to fig. 5, there is shown a combination of a sapphire sensor 1, a sensor protector 2, a sensor pull barrel 3 and an armored cable 5, wherein the sapphire sensor 1 and the armored cable 5 are securely connected by the sensor protector 2, the sapphire sensor 1 and the sensor protector 2 are both disposed in the sensor pull barrel 3, and the sensor pull barrel 3 is fixed on a pipeline, thereby further protecting the sensor by the sensor pull barrel 3; the tow cylinder itself is not sealed and does not interfere with the measurement of the environmental parameters by the sapphire sensor 1.

Fig. 10 is a schematic cross-sectional structural view of a wellhead blowout preventer for armored fiber optic cables in a downhole temperature and pressure monitoring system based on sapphire fiber optic sensors according to an embodiment of the present invention; fig. 11 is a schematic structural diagram that overlooks that is used for wellhead blowout preventer of armoured optical cable among the temperature pressure monitoring system in pit based on sapphire fiber sensor according to the utility model discloses an embodiment.

Referring to fig. 10-11, the wellhead blowout preventer 15 for armored fiber optic cables of embodiments is used to prevent blowout of a leak caused by a fracture in a downhole armored fiber optic cable 5. The armor optical cable 5 is after the fracture takes place in the pit, and pressure will pass to ground through 5 inside of armor optical cable in the pit, through using the utility model discloses a well head blowout preventer 15 can be blocked the pressure that passes to the well head in the pit in the inside cavity of well head blowout preventer 15, treat cracked armor optical cable 5 in the pit and handle the back well, can prevent the blowout from to the pressure in the cavity in the pit from this.

More specifically, the wellhead blowout preventer 15 for armored fiber optic cables of embodiments may include a high-pressure pipe mounting adapter 15-1, a high-pressure hose 15-2, a connection flange 15-3, a pressure chamber 15-7, a pressure-resistant upper flange 15-16, a pressure gauge 15-17, an ultrahigh-pressure manual needle valve 15-20, and a fiber splicing cassette 15-21.

A first through hole 151 is formed on the right side wall of the pressure chamber body 15-7, a second through hole 152, a third through hole 153 and a fourth through hole 154 are formed on the left side wall, and the upper portion is opened, and a pressure-resistant upper flange 15-16 is fixed on the opened upper portion of the pressure chamber body 15-7 to seal the pressure chamber body 15-7, thereby forming a cavity 15-14 in the pressure chamber body 15-7. The upper pressure-resistant flange 15-16 can be screwed to the pressure chamber 15-7 and between them a second sealing ring 15-15 is arranged, as shown in the figure, the second sealing ring 15-15 being arranged at a step inside said pressure chamber 15-7. A pressure gauge 15-17 is fixed to the pressure-resistant upper flange 15-16 for measuring the internal pressure of the pressure chamber 15-7, i.e. the pressure in the cavity 15-14.

Referring to the drawings, the armored optical cable 5 passes through a high-pressure pipe mounting adapter 15-1, a high-pressure hose 15-2, a connecting flange 15-3, a metal cone sealing assembly 15-5 and a hold-down stud 15-6 after passing through a Christmas tree, which is not shown, and enters the inside of a pressure cavity 15-7, namely a cavity 15-14.

More specifically, the right side of the high-pressure hose 15-2 is connected with a high-pressure pipe mounting adapter 15-1 through threads, the left side of the high-pressure hose 15-2 is connected with the connecting flange 15-3 through threads, and a fixing compression stud 15-6 is connected at a threaded hole in the left side of the connecting flange 15-3; and a metal cone sealing assembly 15-5 is arranged in the threaded hole on the left side of the connecting flange 15-3 and on the right side of the pressing stud 15-6. The connecting flange 15-3 can be fixed to the pressure chamber 15-7 by means of screws, and a first sealing ring 15-4 is arranged between the connecting flange and the pressure chamber. As shown in the figure, a first sealing ring 15-4 is arranged in the left groove of the connecting flange 15-3. The armored cable 5 is thus sealingly secured to the connection flange 15-3 and enters the interior of the pressure chamber 15-7 through the first through hole 151.

As shown, the left side wall of the pressure chamber 15-7 is further formed with a second through hole 152, a third through hole 153 and a fourth through hole 154.

The third through hole 153 is fixedly provided with an ultrahigh pressure manual control needle valve 15-20, and when the armored optical cable 5 is broken in the well, the cavity 15-14 can be emptied through the ultrahigh pressure manual control needle valve 15-20 after the breakage is processed.

The second through hole and the fourth through hole are similar to the channel formed in the connecting flange 15-3, the left side is formed with a threaded hole with a larger diameter for screwing the pressing stud 15-6 and pressing the metal cone sealing assembly 15-5, and the right side is formed with a channel with a smaller diameter, thereby sealing and fixing the non-porous core rod 15-13 or the porous core rod 15-10 passing through the fourth through hole or the second through hole. The fourth through-hole and the non-porous mandrel 15-13 therein may be an alternative to the second through-hole and the porous mandrel 15-10 therein.

More specifically, the outgoing optical fiber 15-8 passes through the through hole of the holey plug 15-10, and may be hermetically fixed in the holey plug 15-10 by an adhesive 15-9 such as an epoxy adhesive, for example, 353ND glue or the like. For example, the holey core rod 15-10 has a larger diameter of the through hole on the side facing the chamber 15-14 and a smaller diameter of the through hole on the other side, slightly larger than the diameter of the outgoing optical fiber 15-8, and the adhesive 15-9 is disposed in the larger diameter through hole. One end of the outgoing optical fiber 15-8 is connected, e.g., fused, to the optical fiber in the armored cable 5 in the cavity 15-14, and the other end is connected (e.g., fused) to one end of the buried cable 16.

As shown, a fiber splicing cassette 15-21 is mounted to the left of the pressure chamber 15-7, for example by a screw connection. The non-porous core rod 15-13, one end of the porous core rod 15-10 far away from the cavity 15-14 and the ultrahigh pressure manual control needle valve 15-20 are arranged in the optical fiber splicing box 15-21. And a waterproof cable joint 15-12 is arranged on the outer surface of the left side of the optical fiber splicing box 15-21. In addition, an optical cable fixing seat 15-11 is fixed on the left surface inside the optical fiber splicing box 15-21, and an underground optical cable 16 passes through the waterproof cable joint 15-12, enters the optical fiber splicing box 15-21 and is fixed on the optical cable fixing seat 15-11, and then is connected with one end of the led-out optical fiber 15-8 in a fusion mode inside the optical fiber splicing box 15-21.

In addition, referring to fig. 11, foldable handles 15-19 can be installed on the front and rear sides of the pressure chamber 15-7, and a fixed installation plate 15-18 can be installed on the bottom of the pressure chamber 15-7.

Fig. 12 is a schematic structural diagram of an armored cable splicing protection device in a downhole temperature and pressure monitoring system based on a sapphire optical fiber sensor according to an embodiment of the present invention. Referring to fig. 1 and 12, after the armored cable 5 passes through the packer 8, it needs to be connected with another armored cable, and because of the inherent fragility and fragility, the splicing point of the armored cable is generally fragile and needs protection. In the embodiment, the armored optical cable splicing protection device 9 is used for fixing and sealing and connecting two sections of armored optical cables to protect splicing points.

More specifically, the armored optical cable splicing protection device 9 comprises a middle protection tube 9-2, a second sealing connection assembly and a third sealing connection assembly, wherein the two sealing connection assemblies are respectively fixed at two ends of the middle protection tube 9-2 in a sealing mode, two sections of armored optical cables 5 can respectively penetrate through the two sealing connection assemblies in a sealing mode and are spliced in the middle protection tube 9-2, and therefore a splicing point 9-1 is located in the middle protection tube 9-2; in addition, the whole armored cable splice protector 9 can be fixed in the splice dragging cylinder 10 for further protection, and the function is similar to that of the sensor dragging cylinder 3.

The second and third seal connection assemblies have the same structure as the first seal connection assembly, and thus are not described in detail. For example, the seal connection assembly may include a splice protector tail end 9-3, a tail seal stud 9-7, a tail connector 9-11, and a tail hold down stud 9-12, among others.

The utility model discloses a temperature pressure monitoring system in pit based on sapphire optical fiber sensor, through installing sapphire sensor on the sensor dragging barrel and following the tubular column and go into the well in, the laser instrument in the demodulation appearance sends laser, and light signal arrives sapphire sensor in the pit through optic fibre; the sapphire sensor reflects laser emitted by the laser, and when the ambient temperature and the ambient pressure change, a spectral signal reflected from the sapphire sensor also changes correspondingly; the demodulator 17 receives the spectrum reflected from the sapphire sensor; the values of temperature and pressure were obtained by analysis of the interference spectrum. The problems that the detection data is inaccurate and real-time detection is not achieved are solved; and the system does not have electronic components in the oil gas well, so that the problem of short service life is solved. The underground temperature and pressure parameters are monitored in real time in the whole service life of the oil and gas well, and the measured parameter data are transmitted to a demodulator on the ground in real time to be displayed and stored. The real-time downhole temperature and pressure parameter data can assist production engineers and oil reservoir analysts in optimizing production in real time, diagnosing faults in time and dynamically knowing the change trend of the oil reservoir, and is an important decision basis for planning the oil reservoir and making production tasks. In addition, the underground armored optical cable splicing protection device adopts a mode of combining and sealing a plurality of components, so that the risk of breakage and fracture of splicing points caused by the stress of the optical cable near the splicing points of the optical cable can be avoided or reduced; the wellhead blowout preventer 15 may prevent the risk of a blowout from occurring if the armored fiber optic cable 5 breaks downhole, causing a leak.

The specific embodiments are given above, but the present invention is not limited to the above-described embodiments. The basic idea of the present invention lies in the above basic scheme, and to the ordinary skilled in the art, according to the present invention, the model, formula, parameter of various deformation are designed without the need of creative labor. Variations, modifications, substitutions and alterations of the embodiments may be made without departing from the principles and spirit of the invention, which is also within the scope of the invention.

Claims

1. The utility model provides a temperature pressure monitoring system in pit based on sapphire optical fiber sensor which characterized in that: the device comprises a sapphire sensor (1), a sensor protector (2), an armored optical cable (5), a wellhead blowout preventer (15) and a demodulator (17), wherein the sapphire sensor (1) is connected with the armored optical cable (5) through the sensor protector (2), the armored optical cable (5) extends and is connected to the wellhead blowout preventer (15), and the demodulator (17) is connected with the armored optical cable (5) through an underground optical cable (16) and the wellhead blowout preventer (15);

the sapphire pressure-resistant diaphragm (1-0-1) and the sapphire temperature-resistant diaphragm (1-0-3) are respectively welded at two ends of the sapphire pressure-resistant cavity (1-0-2) through ceramic powder sintering, so that a pressure-sensitive cavity (1-0-6) is formed, one end of the sapphire Palo cavity main body (1-0-4) is welded on the sapphire temperature-resistant diaphragm (1-0-3) through ceramic powder sintering, and the sapphire temperature-resistant diaphragm (1-0-3) is arranged between the sapphire Palo cavity main body (1-0-4) and the sapphire pressure-resistant cavity (1-0-2); the collimator (1-0-5) is fixed in the inner chamber of the sapphire Palo cavity body (1-0-4).

2. The downhole temperature and pressure monitoring system based on a sapphire fiber sensor as defined in claim 1, wherein the sapphire sensor (1) further comprises a sapphire sensor body (1-2) and a connector,

the sapphire sensor comprises a sapphire sensor body (1-2) and a pressure inlet end, wherein the sapphire sensor unit (1-0) is arranged in an inner cavity of the sapphire sensor body (1-2), a sapphire pressure-resistant diaphragm (1-0-1) faces the pressure inlet end, and a sapphire Parro cavity body (1-0-4) is hermetically fixed in the inner cavity on one side of the outlet end;

the high-temperature optical fiber (1-6) passes through the outlet end and penetrates through the connecting piece, the connecting piece comprises a connecting shaft (1-5), two sensor connecting studs (1-4) and two limiting rings (1-3), the two sensor connecting studs (1-4) are respectively sleeved on the two sides of the connecting shaft (1-5), the thread directions of the two sensor connecting studs face to the two sides respectively, the two ends of the connecting shaft (1-5) are connected with the two limiting rings (1-3) through threads, and one end of the connecting piece is connected with the outlet end of the sapphire sensor main body (1-2) in a sealing mode through the thread connection of one sensor connecting stud (1-4).

3. A downhole temperature and pressure monitoring system based on sapphire optical fiber sensors according to claim 2, wherein the sensor protector (2) is sealingly connected to the other end of the connector, whereby a fusion splice (5-2) where a high temperature optical fiber (1-6) is fused with an optical fiber (5-1) in an armored optical cable (5) passing through the sensor protector (2) can be located within the sensor protector (2) to be protected;

4. The downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor as claimed in claim 3, further comprising an armored cable splicing protection device (9) for hermetically connecting two sections of armored cables;

the armored optical cable splicing protection device (9) comprises a middle protection tube (9-2), a second sealing connection assembly and a third sealing connection assembly, wherein the two sealing connection assemblies are respectively fixed at two ends of the middle protection tube (9-2) in a sealing mode, two sections of armored optical cables can respectively penetrate through the two sealing connection assemblies in a sealing mode and are spliced in the middle protection tube (9-2), and therefore a splicing point (9-1) is located in the middle protection tube (9-2);

5. A downhole temperature and pressure monitoring system based on sapphire optical fiber sensors according to claim 3 or 4, further comprising a sensor drag cylinder (3) and a connector drag cylinder (10), the sensor drag cylinder (3) being arranged to enclose the sensor protector (2) and the sapphire sensor (1), the connector drag cylinder (10) being arranged to enclose the armored cable splice protector (9).

6. The sapphire optical fiber sensor-based downhole temperature and pressure monitoring system according to claim 1, wherein the wellhead blowout preventer (15) comprises a high-pressure pipe mounting adapter (15-1), a high-pressure hose (15-2), a connecting flange (15-3), a pressure cavity (15-7), a pressure-resistant upper flange (15-16), a pressure gauge (15-17), a first sealing assembly and a second sealing assembly;

and the second sealing component is arranged at the second through hole (152) and is used for hermetically fixing the outgoing optical fiber (15-8) connected with the armored optical cable (5) in the pressure cavity (15-7) on the left side wall.

7. The downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor as claimed in claim 6, wherein the wellhead blowout preventer (15) further comprises an optical fiber splicing box (15-21) arranged at the left side of the pressure cavity (15-7), a waterproof cable joint (15-12) is arranged on the optical fiber splicing box (15-21), one end of the underground optical cable (16) enters the optical fiber splicing box (15-21) through the waterproof cable joint (15-12) and is connected with the outgoing optical fiber (15-8), and the other end of the underground optical cable is connected with the demodulator (17).

8. The downhole temperature and pressure monitoring system based on the sapphire optical fiber sensor as claimed in claim 6, wherein a third through hole (153) and a fourth through hole (154) are formed in the left side wall of the pressure cavity (15-7), an ultrahigh pressure manual needle valve (15-20) is arranged on the third through hole (153), and a non-porous core rod (15-13) is hermetically fixed on the fourth through hole (154) through a third sealing assembly.

9. The sapphire fiber optic sensor-based downhole temperature and pressure monitoring system as claimed in claim 3, wherein the protector tail end (2-3) further comprises a first detection hole (2-18) formed in a side wall for detecting the tightness between the tail end seal stud (2-7) and the protector tail end (2-3); the tail end sealing stud (2-7) further comprises a second detection hole (2-19) formed in the side wall and used for detecting the tightness between the tail end sealing stud (2-7) and the tail end connecting piece (2-11).

10. The sapphire fiber optic sensor-based downhole temperature and pressure monitoring system of claim 2, wherein the sapphire sensor (1) further comprises a sensor pressure inlet piece (1-1) connected to the pressure inlet end of the sapphire sensor body (1-2).