阅读说明：本技术 基于涡流管的井下温差发电系统及其发电方法、设计实现方法 (Underground temperature difference power generation system based on vortex tube and power generation method and design implementation method thereof ) 是由 刘均荣 于 2020-12-02 设计创作，主要内容包括：本发明涉及基于涡流管的井下温差发电系统及其发电方法、设计实现方法。该系统包括油管和套管,油管与套管之间的区域为油套环空腔体。油套环空腔体内设有发电部分保护套和蓄电部分保护套。发电部分保护套内设有涡流管和温差发电装置；发电部分保护套与温差发电装置及涡流管之间的区域为发电部分环空腔体。涡流管的入口处连接有流体入口装置,涡流管轴向两端的端口处分别设有低温流体出口和高温流体出口。温差发电装置包括支撑部件和温差发电组。蓄电部分保护套内设有升压稳压器和蓄电模块。本发明能够在不需要任何外部供电的情况下,利用井下流体流过涡流管产生的温度差,即可实现自主发电,为井下设备提供稳定电能。(The invention relates to an underground temperature difference power generation system based on a vortex tube, a power generation method and a design realization method thereof. The system comprises an oil pipe and a casing, wherein an oil sleeve ring cavity body is arranged in an area between the oil pipe and the casing. The oil lantern ring cavity is internally provided with a power generation part protective sleeve and a power storage part protective sleeve. A vortex tube and a temperature difference power generation device are arranged in the power generation part protective sleeve; the area between the power generation part protective sleeve, the temperature difference power generation device and the vortex tube is a power generation part annular cavity body. The inlet of the vortex tube is connected with a fluid inlet device, and the ports of the two axial ends of the vortex tube are respectively provided with a low-temperature fluid outlet and a high-temperature fluid outlet. The thermoelectric generation device comprises a supporting component and a thermoelectric generation set. A boosting voltage stabilizer and a power storage module are arranged in the power storage part protection sleeve. The invention can realize autonomous power generation by utilizing the temperature difference generated when underground fluid flows through the vortex tube without any external power supply, and provides stable electric energy for underground equipment.)

1. A downhole thermoelectric power generation system based on a vortex tube comprises a shaft; the shaft comprises an oil pipe (12) and a casing pipe (11) which are sequentially arranged from inside to outside, and an oil sleeve ring cavity body (13) is arranged in the area between the oil pipe (12) and the casing pipe (11); the method is characterized in that: a power generation part protective sleeve (23) and a power storage part protective sleeve (27) connected with the power generation part protective sleeve (23) are arranged in the oil sleeve ring cavity (13);

a vortex tube (100) and a temperature difference power generation device (300) are arranged in the power generation part protective sleeve (23); the region between the power generation part protective sleeve (23) and the temperature difference power generation device (300) and the vortex tube (100) is a power generation part annular cavity body (29);

a fluid inlet device (24) is connected to an inlet of the vortex tube (100), and a low-temperature fluid outlet (26) and a high-temperature fluid outlet (25) are respectively arranged at ports at two axial ends of the vortex tube (100);

the thermoelectric power generation device (300) comprises a supporting component (311) with an inner cavity and a plurality of thermoelectric power generation sets which are arranged on the outer wall of the supporting component (311) and are connected in parallel along the axial direction of the outer wall of the supporting component (311); the inner cavity of the supporting component (311) is a cold fluid channel (301); the thermoelectric generation set comprises a plurality of thermoelectric generation units which are connected in series along the circumferential direction of the outer wall of the supporting component (311); the thermoelectric power generation unit comprises a cold-end insulated heat-release component (316), a cold-end metal conductor group (315), a thermoelectric power generation semiconductor group (314), a hot-end metal conductor group (313) and a hot-end insulated heated component (312) which are arranged from inside to outside in sequence;

the fluid inlet device (24) is communicated with the oil sleeve ring cavity body (13) through the power generation part protective sleeve (23); the low-temperature fluid outlet (26) is connected with the inlet of the cold fluid channel (301); the high-temperature fluid outlet (25) is communicated with the annular cavity body (29) of the power generation part;

a boost voltage stabilizer (41) electrically connected with the thermoelectric power generation device (300) and an electric power storage module (42) electrically connected with the boost voltage stabilizer (41) are arranged in the electric power storage part protective sleeve (27); an outlet of the cold fluid channel (301) is provided with a spent cryogenic fluid outlet (21), and the spent cryogenic fluid outlet (21) is communicated with an inner cavity of the protective sleeve (27) of the power storage part.

2. The vortex tube based downhole thermoelectric generation system of claim 1, wherein: the outer diameters of the power generation part protective sleeve (23) and the power storage part protective sleeve (27) are the same, the power generation part protective sleeve and the power storage part protective sleeve are connected into a whole from bottom to top along the axial direction of a shaft, and the power generation part protective sleeve and the power storage part protective sleeve are connected to the outer wall of an oil pipe (12) through a fixer (31).

3. The vortex tube based downhole thermoelectric generation system of claim 1, wherein: a first discharge check valve (32) is arranged on the power generation part protective sleeve (23); and a second discharge check valve (33) is arranged on the power storage part protective sleeve (27).

4. The vortex tube based downhole thermoelectric generation system of claim 1, wherein: and a hot end regulating valve (28) is arranged at the high-temperature fluid outlet (25).

5. The vortex tube based downhole thermoelectric generation system of claim 1, wherein: the thermoelectric power generation device (300) is connected with the boosting voltage stabilizer (41) through the first lead group (51), the boosting voltage stabilizer (41) is connected with the electric storage module (42) through the second lead group (52), and the electric storage module (42) is connected with the underground electric equipment (43) through the third lead group (53).

6. The vortex tube based downhole thermoelectric generation system of claim 1, wherein: the vortex tube (100) is a counter-flow vortex tube or a forward-flow vortex tube.

7. The vortex tube based downhole thermoelectric generation system of claim 1, wherein: the supporting component (311) is a hollow cylinder, and a middle cavity of the supporting component is a cold fluid channel (301).

8. The power generation method of the downhole thermoelectric power generation system based on the vortex tube as claimed in any one of claims 1 to 7, wherein: the method comprises the following steps:

s11, the high-pressure fluid flows downwards along the oil pipe (12), when the high-pressure fluid flows through the fluid inlet device (24), a part of the high-pressure fluid enters the vortex tube (100) from the fluid inlet device (24);

s12, making the fluid entering the vortex tube (100) make strong-swirl turbulent motion in the vortex tube (100), and dividing the fluid into two streams of fluid with opposite flowing directions after momentum and heat exchange, wherein one stream is high-temperature fluid, and the other stream is low-temperature fluid; high-temperature fluid flows into the power generation part annular cavity fluid (29) from the high-temperature fluid outlet (25), and low-temperature fluid flows into the cold fluid channel (301) from the low-temperature fluid outlet (26);

s13, the high-temperature fluid entering the power generation part annular cavity body (29) flows through the outer wall of a hot end insulation heated component of the temperature difference power generation device (300) to form a high-temperature end of the temperature difference power generation device (300), and then is discharged into the oil annular ring cavity body (13) through the first discharge check valve (32);

s14, after entering a cold fluid channel (301), the low-temperature fluid flows through the inner wall of a supporting part (311) to form a low-temperature end of the thermoelectric power generation device (300), then enters an electric power storage part protective sleeve (27) through a spent low-temperature fluid outlet (21), provides a low-temperature protective environment for a boosting voltage stabilizer (41) and an electric power storage module (42), and finally flows out of an oil jacket ring cavity body (13) through a second discharge check valve (33);

s15, generating electric energy by the temperature difference generating device (300) under the action of the temperature difference between the high temperature end and the low temperature end;

s16, electric energy generated by the thermoelectric generation device (300) flows into the voltage boosting and stabilizing device (41) through the first lead group (51) to be boosted, stabilized and adjusted, then the second lead group (52) is stored in the electric storage module (42), and the electric storage module (42) provides electric energy for underground electric equipment through the third lead group (53).

9. The method of generating power for a vortex tube based downhole thermoelectric generation system of claim 8, wherein: the fluid is a gas.

10. The design implementation method of the downhole thermoelectric power generation system based on the vortex tube as claimed in any one of claims 1 to 7, wherein: the method comprises the following steps:

s21, determining structural parameters of the underground thermoelectric power generation system by using a numerical simulation method; firstly, establishing a physical model and a numerical model of a vortex tube (100) and a temperature difference power generation device (300) by adopting fluid flow numerical simulation software; then, under the condition that the structure and the size of the vortex tube (100) and the performance parameters of the adopted thermoelectric material are fixed, taking the fluid flow range, the fluid temperature range and the fluid pressure range entering the vortex tube (100) as input variables, taking the highest power generation efficiency of the thermoelectric power generation device (300) as a target, and adopting a particle swarm optimization algorithm to optimize the optimal outer diameter of the supporting component (311), the optimal inner diameter of the supporting component (311), the optimal length of the supporting component (311) and the optimal inner diameter of the power generation part protective sleeve (23) which are suitable for the fluid flow range, the fluid temperature range and the fluid pressure range; finally, determining the outer diameter of the power generation part protective sleeve (23) according to the size of the oil sleeve annulus (13) and the compressive strength of the material used by the power generation part protective sleeve (23);

s22, according to the total power consumption requirement of the underground electric equipment and the pressure field distribution, the temperature field distribution and the fluid flow of the fluid flowing in the oil pipe (12) along the depth of the shaft, adopting the structural parameters determined in the step S21, under the condition that the structure and the size of the vortex tube (100) and the performance parameters of the adopted thermoelectric material are certain, aiming at meeting the total power consumption of the underground electric equipment, adopting a particle swarm optimization algorithm to determine the required fluid flow, the fluid temperature and the fluid pressure entering the vortex tube (100), further determining the opening size of a fluid inlet device (24) and the depth position in the well according to the pressure field distribution and the temperature field distribution data of the fluid flowing in the oil pipe (12) along the depth of the shaft, further determining a power generation part protective sleeve (23) and a power storage part protective sleeve (27) which are sequentially connected into a whole from bottom to top, and then arranging a lantern ring oil cavity body (13) between the oil pipe (12) and the sleeve (11) through a fixer (31) A depth position of;

s23, determining the number and the arrangement depth of underground electric equipment according to the parameter measurement requirement and the production control requirement of underground production;

s24, designing a well string structure according to the results of the steps S21 to S23;

s25, firstly, connecting a fluid inlet device (24), a vortex tube (100), a low-temperature fluid outlet (26), a temperature difference power generation device (300), a spent low-temperature fluid outlet (21), a first lead group (51), a hot end regulating valve (28) and a high-temperature fluid outlet (25), setting the regulating position of the hot end regulating valve (28), and then packaging in a power generation part protective sleeve (23); secondly, a first lead group (51), a boost voltage stabilizer (41), a second lead group (52), an electric storage module (42) and a third lead group (53) are connected in sequence and then packaged in an electric storage part protective sleeve (27); finally, the power generation part protective sleeve (23) and the power storage part protective sleeve (27) are connected to form a complete underground thermoelectric power generation system;

s26, selecting a proper oil pipe short section according to the length of the underground thermoelectric power generation system assembled in the step S25, connecting the fluid inlet device (24) with the oil pipe short section, and fixing the whole underground thermoelectric power generation system on the outer wall of the oil pipe short section through a fixer (31);

s27, connecting an oil pipe (12), underground electric equipment (43), a third lead group (53) and the oil pipe short section assembled in the step S26 according to the pipe column structure designed in the step S24, and completing the well entry of the pipe column.

Technical Field

The invention relates to the technical field of oil and gas field development, in particular to an underground temperature difference power generation system based on a vortex tube, a power generation method and a design implementation method thereof.

Background

Most small devices used for reservoir dynamic monitoring and production control are currently powered by disposable or rechargeable batteries. These conventional chemical batteries have disadvantages of large size, short life, limited power supply and the need for periodic replacement, and cannot meet the long-term downhole production monitoring and control requirements. Therefore, it is important to find a long-term stable underground power generation technology.

Vortex tubes are a simple energy separation device that can separate an inlet working fluid into a stream of fluid at a temperature above the inlet temperature and a stream of fluid at a temperature below the inlet temperature with a certain inlet-outlet pressure differential. After decades of research and development, the vortex tube plays an important role in the fields of scientific research and industrial application due to the unique advantages of simplicity, no moving parts, low cost, safe and reliable performance and the like, and is widely applied to various aspects such as processing and manufacturing, biomedicine, precise instruments, aerospace, chemical treatment and the like.

In recent years, thermoelectric power generation technology has been gradually developed with the progress of semiconductor material manufacturing technology and process. When two ends of a pair of PN semiconductors are respectively in different temperature environments, due to the Seebeck effect, a temperature difference electromotive force is formed between the high-temperature end and the low-temperature end of the PN semiconductor, and heat energy is directly converted into electric energy. Some studies have shown that even a temperature difference of only 10 c across the PN semiconductor can generate higher electrical energy.

In the underground production process, formation fluid carries energy such as heat energy, kinetic energy, potential energy and the like, and the temperature and the pressure of the fluid are gradually reduced in the flowing process from the bottom to the top of a well, so that the method for meeting the long-time continuous electricity utilization requirement of underground equipment and sensors by utilizing the self energy of the formation fluid is particularly important. Thermoelectric generation is an effective solution.

The existing underground thermoelectric power generation method realizes power generation by artificially injecting cold fluid, and the process is relatively complex. Such as the article Analysis and modeling of thermal power generation in oil wells: in A porous power supply for downhole use in-situ geotherm energy, the downhole generated energy can reach 800 watts under the conditions that the length is 200 meters, the temperature of stratum produced fluid is 125 ℃ and the temperature of artificially injected fluid is 20 ℃ by serially connecting temperature difference power generation modules. Typically, formation production fluids flowing up the wellbore are subjected to heat exchange with the surrounding formation, and the temperature differential of the formation production fluids does not vary by more than 5 ℃ over a 100 meter range along the wellbore flow direction. If only the temperature difference of the fluid along the flowing direction of the shaft is used for temperature difference power generation, the structure of the required temperature difference power generation device is very long and thin, the size is very large, and the temperature difference power generation is carried out by transferring the high-temperature heat of the formation produced fluid at the lower part of the shaft and the low-temperature heat of the upper part of the shaft to the hot end and the cold end of the temperature difference power generation device, so that the structural design of the shaft temperature difference power generation device is very complex. Meanwhile, the power generation amount is low due to small temperature difference change along the direction of the shaft. In the text of comparison and analysis of performances of single-phase (gas phase) and gas-liquid two-phase vortex tubes published in low-temperature engineering journals, such as hamming, the temperature changes of the single-phase (gas phase) fluid and the gas-liquid two-phase fluid at the outlet of the vortex tube can reach about 40 ℃ and about 10 ℃ respectively under the conditions that the pressure ratio of the inlet to the outlet of the vortex tube is 1.665, the component of cold air flow is 0.60, and the length of the hot end tube is 300 mm, namely the length-diameter ratio is 8.571. Chinese patent CN 105579661B discloses a system for obtaining downhole energy from isothermal sections of a wellbore, in which the inlet of a vortex tube is directly connected with the formation produced fluid through a casing opening, the formation produced fluid all enters the vortex tube, and the installation location is in the producing zone. Cold and hot fluid from the vortex tube of the system is firstly contacted with the two thermocouples, and the two thermocouples are respectively contacted with the cold and hot ends of the temperature difference power generation device, so that heat is lost in the transfer process, and the heat transfer effect is poor.

In view of this, when the downhole fluid flows through the vortex tube, the two streams of cold and hot fluid generated respectively flow through the two ends of the PN semiconductor, so as to generate power underground, thereby providing electric power for electrical equipment such as downhole sensors and control devices.

Disclosure of Invention

The invention aims to provide an underground temperature difference power generation system based on a vortex tube, a power generation method and a design realization method thereof, wherein the underground temperature difference power generation system can overcome the defects in the prior art, can realize autonomous power generation by utilizing the temperature difference generated when underground fluid flows through the vortex tube under the condition of not needing any external power supply, and provides stable electric energy for underground equipment; and the temperature change of tens of degrees can be obtained within a small scale range of the length of the vortex tube of several meters, the temperature difference required by the temperature difference power generation device can be sufficiently provided, and the power generation efficiency is greatly improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

a downhole thermoelectric power generation system based on a vortex tube comprises a shaft. The pit shaft includes oil pipe and the sleeve pipe that sets gradually from inside to outside, and the region between oil pipe and the sleeve pipe is the oil lantern ring cavity body. And a power generation part protective sleeve and a power storage part protective sleeve connected with the power generation part protective sleeve are arranged in the oil sleeve ring cavity.

A vortex tube and a temperature difference power generation device are arranged in the power generation part protective sleeve; the area between the power generation part protective sleeve, the temperature difference power generation device and the vortex tube is a power generation part annular cavity body.

The inlet of the vortex tube is connected with a fluid inlet device, and the ports of the two axial ends of the vortex tube are respectively provided with a low-temperature fluid outlet and a high-temperature fluid outlet.

The thermoelectric power generation device comprises a supporting component with an inner cavity and a plurality of thermoelectric power generation sets which are arranged on the outer wall of the supporting component and are connected in parallel along the axial direction of the outer wall of the supporting component; the inner cavity of the supporting component is a cold fluid channel; the thermoelectric power generation set comprises a plurality of thermoelectric power generation units which are connected in series along the circumferential direction of the outer wall of the supporting component; the thermoelectric power generation unit comprises a cold-end insulated heat-releasing component, a cold-end metal conductor group, a thermoelectric power generation semiconductor group, a hot-end metal conductor group and a hot-end insulated heated component which are sequentially arranged from inside to outside.

The fluid inlet device penetrates through the power generation part protective sleeve and is communicated with the oil sleeve ring cavity body; the low-temperature fluid outlet is connected with the inlet of the cold fluid channel; the high-temperature fluid outlet is communicated with the annular cavity of the power generation part.

A boosting voltage stabilizer electrically connected with the temperature difference power generation device and a power storage module electrically connected with the boosting voltage stabilizer are arranged in the power storage part protection sleeve; and a spent low-temperature fluid outlet is arranged at the outlet of the cold fluid channel and is communicated with the inner cavity of the power storage part protecting sleeve.

Furthermore, the outer diameters of the power generation part protective sleeve and the power storage part protective sleeve are the same, and the power generation part protective sleeve and the power storage part protective sleeve are connected into a whole from bottom to top along the axial direction of the shaft and are connected to the outer wall of the oil pipe through a fixer.

Further, a first discharge check valve is arranged on the protective sleeve of the power generation part; and a second discharge check valve is arranged on the protective sleeve of the power storage part.

Furthermore, a hot end regulating valve is arranged at the high-temperature fluid outlet.

Furthermore, thermoelectric generation device links to each other with the stabiliser that steps up through first wire group, and the stabiliser that steps up links to each other with the electric power storage module through second wire group, and the electric power storage module links to each other with electrical equipment in the pit through third wire group.

Further, the vortex tube is a counter-flow vortex tube or a forward-flow vortex tube.

Further, the supporting component is a hollow cylinder, and a middle cavity of the supporting component is a cold fluid channel.

The invention also relates to a power generation method of the underground temperature difference power generation system based on the vortex tube, which comprises the following steps:

s11, the high pressure fluid flows down the oil pipe, and when flowing through the fluid inlet device, a part of the high pressure fluid enters the vortex tube from the fluid inlet device.

S12, making the fluid entering the vortex tube do strong-rotation turbulent motion in the vortex tube, dividing the fluid into two streams of fluid with opposite flowing directions after momentum and heat exchange, wherein one stream is high-temperature fluid, and the other stream is low-temperature fluid; the high-temperature fluid flows into the power generation part annular cavity fluid from the high-temperature fluid outlet, and the low-temperature fluid flows into the cold fluid channel from the low-temperature fluid outlet.

S13, the high-temperature fluid entering the annular cavity body of the power generation part flows through the outer wall of the hot end insulation heated component of the temperature difference power generation device to form a high-temperature end of the temperature difference power generation device, and then is discharged into the annular cavity body of the oil sleeve through the first discharge check valve.

And S14, after entering the cold fluid channel, the low-temperature fluid flows through the inner wall of the supporting component to form a low-temperature end of the thermoelectric power generation device, then enters the electric power storage part protective sleeve through the low-temperature fluid exhaust outlet to provide a low-temperature protective environment for the boosting voltage stabilizer and the electric power storage module, and finally flows out of the oil jacket ring cavity body through the second discharge check valve.

And S15, generating electric energy by the temperature difference between the high-temperature end and the low-temperature end of the temperature difference generating device.

S16, electric energy generated by the temperature difference power generation device flows into the voltage boosting and stabilizing device through the first lead group to be boosted and stabilized, and then is stored in the electric storage module through the second lead group, and the electric storage module provides electric energy for underground electric equipment through the third lead group, so that underground power generation and electric storage are realized. The underground electric equipment is a low-power consumption temperature sensor, a pressure sensor, a flowmeter, a flow control valve or underground communication equipment. The number of downhole electrical devices is determined based on downhole measurement and control requirements. The underground electric equipment obtains power supply from the power storage module through the third lead group according to the power utilization requirement. The number of the third conductor sets is determined according to the number of the downhole electric equipment.

Further, the fluid is a gas.

The invention also relates to a design implementation method of the underground thermoelectric power generation system based on the vortex tube, which comprises the following steps:

and S21, determining the structural parameters of the underground thermoelectric power generation system by using a numerical simulation method. Firstly, fluid flow numerical simulation software is adopted to establish a physical model and a numerical model of the vortex tube and the temperature difference power generation device. Then, under the condition that the structure and the size of the vortex tube and the performance parameters of the adopted thermoelectric material are fixed, the fluid flow range, the fluid temperature range and the fluid pressure range entering the vortex tube are used as input variables, the highest power generation efficiency of the thermoelectric power generation device is taken as a target, and the particle swarm optimization algorithm is adopted to optimize the optimal outer diameter of the supporting part, the optimal inner diameter of the supporting part (namely the radius of a cold fluid channel), the optimal length of the supporting part and the optimal inner diameter of the power generation part protection sleeve which are suitable for the fluid flow range, the fluid temperature range and the fluid pressure range. And finally, determining the outer diameter of the power generation part protection sleeve according to the annular size of the oil sleeve and the compressive strength of the material used by the power generation part protection sleeve.

S22, according to the total power consumption demand of the underground electric equipment and the pressure field distribution, the temperature field distribution and the fluid flow of the flowing fluid in the oil pipe along the depth of the shaft, adopting the structural parameters determined in the step S21, under the condition that the structure and the size of the vortex tube and the performance parameters of the adopted thermoelectric material are certain, aiming at meeting the total power consumption of underground electric equipment, determining the required fluid flow, fluid temperature and fluid pressure entering the vortex tube by adopting a particle swarm optimization algorithm, further determining the opening size of the fluid inlet device and the depth position in the well according to the pressure field distribution and the temperature field distribution data of the flowing fluid in the oil pipe along the depth of the well bore, further ensuring that the power generation part protective sleeve and the power storage part protective sleeve are sequentially connected into a whole from bottom to top, a depth location in the oil jacket ring cavity body between the oil pipe and the casing is disposed by a retainer.

And S23, determining the number of the downhole electric equipment and the arrangement depth according to the parameter measurement requirement and the production control requirement of the downhole production. For example, if 3 production layers exist, each production layer needs to measure the temperature, and 3 temperature sensors are needed; each layer needs production control, and 3 control valves are needed; thus 6 downhole electrical devices are required; the placement depth corresponds to the pay zone depth.

And S24, designing a well string structure according to the results of the steps S21 to S23.

S25, firstly, connecting a fluid inlet device, a vortex tube, a low-temperature fluid outlet, a temperature difference power generation device, a spent low-temperature fluid outlet, a first lead group, a hot end regulating valve and a high-temperature fluid outlet, setting the regulating position of the hot end regulating valve, and then packaging in a power generation part protective sleeve. And secondly, sequentially connecting the first lead group, the boosting voltage stabilizer, the second lead group, the electric storage module and the third lead group, and then packaging in a protective sleeve of the electric storage part. And finally, connecting the power generation part protective sleeve and the power storage part protective sleeve to form a complete underground thermoelectric power generation system.

And S26, selecting a proper oil pipe short section according to the length of the underground thermoelectric power generation system assembled in the step S25, connecting the fluid inlet device with the oil pipe short section, and fixing the whole underground thermoelectric power generation system on the outer wall of the oil pipe short section through a fixer.

And S27, connecting the oil pipe, the underground electric equipment, the third lead group and the oil pipe short joint assembled in the step S26 according to the pipe column structure designed in the step S24, and completing the entering of the pipe column into the well.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention fully utilizes the energy carried by formation fluid in the underground production process, has sufficient supply and strong sustainability, avoids the problems of cable structure damage, cable voltage drop loss and the like caused by the traditional method of entering a cable from the ground for power supply, and also avoids the problem of battery replacement operation caused by the traditional method of adopting an underground battery for power supply.

(2) The underground thermoelectric power generation system couples the underground production process with the power generation process and the power utilization process, fully utilizes the pressure and temperature energy of fluid flowing in a shaft, and obtains two cold and heat sources with different temperatures and the optimal underground working depth of the underground thermoelectric power generation system required by thermoelectric power generation by combining with the vortex tube. The invention can obtain the temperature change of tens of degrees in a small scale range with the length of the vortex tube of several meters, can sufficiently provide the temperature difference required by the temperature difference power generation device and greatly improves the power generation efficiency.

(3) The invention can realize autonomous power generation by utilizing the temperature difference power generation device arranged underground, the device does not need to be replaced, has low cost and small volume, and can realize continuous power supply to underground small-sized equipment.

(4) The invention can be used for gas wells and oil wells with high gas-oil ratio.

Drawings

FIG. 1 is a schematic diagram of a downhole thermoelectric generation system according to the present invention;

FIG. 2 is a schematic view showing the construction of the thermoelectric power generation device according to the present invention;

FIG. 3 is a schematic view of the thermoelectric generation module according to the present invention.

Wherein:

11. the thermoelectric power generation device comprises a sleeve, 12, an oil pipe, 13, an oil jacket ring cavity body, 100, a vortex tube, 300, a thermoelectric power generation device, 301, a cold fluid channel, 311, a support part, 312, a hot end insulating and heating component, 313, a hot end metal conductor group, 314, a thermoelectric power generation semiconductor group, 315, a cold end metal conductor group, 316, a cold end insulating and heat releasing component, 21, a low-temperature fluid outlet, 23, a power generation part protective sleeve, 24, a fluid inlet device, 25, a high-temperature fluid outlet, 26, a low-temperature fluid outlet, 27, a power storage part protective sleeve, 28, a hot end adjusting valve, 29, a power generation part annular cavity body, 31, a fixer, 32, a first discharge check valve, 33, a second discharge check valve, 41, a boosting voltage stabilizer, 42, a power storage module, 43, a downhole electric equipment, 51, a first lead group, 52, a second lead group, 53 and a third lead group.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

example one

A vortex tube based downhole thermoelectric generation system, as shown in fig. 1, includes a wellbore. The well bore comprises an oil pipe 12 and a casing pipe 11 which are sequentially arranged from inside to outside, and an oil ring cavity body 13 is arranged in the area between the oil pipe 12 and the casing pipe 11. The oil ring hollow cavity 13 is internally provided with a power generation part protective sleeve 23 and a power storage part protective sleeve 27 connected with the power generation part protective sleeve 23.

A vortex tube 100 and a temperature difference power generation device 300 are arranged in the power generation part protective sleeve 23; the area between the power generation part protective sleeve 23 and the thermoelectric power generation device 300 and the vortex tube 100 is a power generation part annular cavity 29.

The inlet of the vortex tube is connected with a fluid inlet device, and the ports of the two axial ends of the vortex tube are respectively provided with a low-temperature fluid outlet and a high-temperature fluid outlet.

As shown in fig. 2 and 3, the thermoelectric generation device 300 includes a support member 311 having an inner cavity, and a plurality of thermoelectric generation sets 314 mounted on an outer wall of the support member 311 and connected in parallel along an axial direction of the outer wall of the support member 311; the inner cavity of the supporting component 311 is a cold fluid channel 301; the thermoelectric generation set comprises a plurality of thermoelectric generation units which are connected in series along the circumferential direction of the outer wall of the supporting component 311; the thermoelectric power generation unit comprises a cold-end insulating heat-release component 316, a cold-end metal conductor group 315, a thermoelectric power generation semiconductor group 314, a hot-end metal conductor group 313 and a hot-end insulating heated component 312 which are arranged from inside to outside in sequence.

The number of thermoelectric generation elements included in one thermoelectric generation set may be 1, 10, 100, or any number, and the specific number is determined according to the size of the space between the outer diameter of the optimized support member 311 and the inner diameter of the power generation part protection sleeve 23 and the length of the thermoelectric generation elements. The thermoelectric generation sets are connected in parallel along the axial direction of the supporting component 311 and closely attached to the outer wall of the supporting component 311 to form a thermoelectric generation device 300; the thermoelectric generation sets included in the thermoelectric generation device 300 may be 1 set, 10 sets, 100 sets, or any number of sets, and the specific number is determined according to the optimized length of the support member 311 and the width of the thermoelectric generation unit. The optimized outer diameter of the support member 311, the inner diameter of the power generation part protection sleeve 23 and the optimized length of the support member 311 are optimized and determined according to the flow rate of the fluid entering the vortex tube 100, the temperature of the fluid, the pressure of the fluid, the structure and the size of the vortex tube 100 and the performance parameters of the adopted thermoelectric material, with the goal of the highest thermoelectric conversion efficiency. The inner diameter of the support component 311, that is, the radius of the cold fluid channel 301, is optimized and determined according to the fluid flow entering the vortex tube 100, the fluid temperature, the fluid pressure, the structure and the size of the vortex tube 100, and the performance parameters of the adopted thermoelectric material, with the goal of maximizing the thermoelectric conversion efficiency. The outer diameter of the power generation part protection sleeve 23 is determined according to the size of the oil sleeve annulus 13 and the compressive strength of the material used for the power generation part protection sleeve 23.

The fluid inlet device 24 passes through the power generation part protection sleeve 23 and is communicated with the oil ring cavity body 13; the low-temperature fluid outlet 26 is connected with the inlet of the cold fluid channel 301; the high-temperature fluid outlet 25 is communicated with the power generation part annular cavity 29.

A boost voltage stabilizer electrically connected with the thermoelectric power generation device and an electric storage module electrically connected with the boost voltage stabilizer are arranged in the electric storage part protective sleeve 27; and a spent low-temperature fluid outlet is arranged at the outlet of the cold fluid channel and is communicated with the inner cavity of the power storage part protecting sleeve.

Further, the outer diameters of the power generation part protection sleeve 23 and the power storage part protection sleeve 27 are the same, and the two are connected into a whole from bottom to top along the shaft axial direction and connected to the outer wall of the oil pipe 12 through the fixer 31.

Further, a first discharge check valve 32 is arranged on the power generation part protection sleeve 23; the power storage portion protection sleeve 27 is provided with a second discharge check valve 33.

Further, a hot end regulating valve 28 is arranged at the high-temperature fluid outlet 25.

Further, the thermoelectric power generation device 300 is connected with the boost regulator 41 through the first lead group 51, the boost regulator 41 is connected with the electric storage module 42 through the second lead group 52, and the electric storage module 42 is connected with the downhole electric equipment 43 through the third lead group 53.

Further, the vortex tube 100 is a counter flow type vortex tube.

Further, the supporting member 311 is a hollow cylinder, and the middle cavity thereof is the cold fluid channel 301.

The working process of the underground temperature difference power generation system based on the vortex tube comprises the following steps:

step 1: selecting a counter-flow vortex tube, aiming at the highest thermoelectric conversion efficiency, optimizing according to the flow rate of fluid entering the vortex tube 100, the temperature of the fluid, the pressure of the fluid, the structure and the size of the vortex tube 100 and performance parameters of an adopted thermoelectric material, and determining the outer diameter of a support part 311, the inner diameter of the support part 311, namely the radius of a cold fluid channel 301, the length of the support part 311 and the inner diameter of a power generation part protective sleeve 23; the outer diameter of the power generation part protective sleeve 23 is determined according to the size of the oil collar cavity body 13 and the compressive strength of the material used for the power generation part protective sleeve 23.

Step 2: according to the total power consumption requirement of downhole equipment and the pressure field distribution and the temperature field distribution of fluid flowing in the oil pipe 12, the opening size of the fluid inlet device 24 and the depth position in a well are determined through optimization calculation by utilizing the fluid flow, the fluid temperature and the fluid pressure entering the vortex tube 100, the structure and the size of the vortex tube 100 and the performance parameters of the adopted thermoelectric material, and then the depth position of the power generation part protecting sleeve 23 and the power storage part protecting sleeve 27 which are sequentially connected into a whole from bottom to top and are arranged in an oil sleeve annulus 13 between the oil pipe 12 and the casing pipe 11 through the fixator 31 is determined.

And step 3: and determining the number of the underground electric equipment and the arrangement depth according to the parameter measurement requirement and the production control requirement of the underground production.

And 4, step 4: designing the structure of the well-entering pipe column shown in the figure 1 according to the results of the steps 1 to 3.

And 5: assembling a well entering pipe column structure, connecting a fluid inlet device 24, a vortex tube 100, a low-temperature fluid outlet 26, a temperature difference power generation device 300, a spent low-temperature fluid outlet 21, a first lead group 51, a hot end regulating valve 28 and a high-temperature fluid outlet 25 in sequence shown in figure 1, setting the regulating position of the hot end regulating valve 28, and then packaging in a power generation part protective sleeve 23; sequentially connecting a first lead group 51, a boosting voltage stabilizer 41, a second lead group 52, an electric storage module 42 and a third lead group 53, and then packaging in an electric storage part protective sleeve 27; finally, the power generation part protective sleeve 23 and the power storage part protective sleeve 27 are connected to form a complete underground thermoelectric power generation system.

Step 6: and (5) selecting a proper oil pipe short section according to the length of the underground thermoelectric power generation system assembled in the step (5), connecting the fluid inlet device 24 with the oil pipe short section, and fixing the whole underground thermoelectric power generation system on the outer wall of the oil pipe short section through the fixer 31.

And 7: and (4) connecting an oil pipe, underground electric equipment, a third lead group 53 and the oil pipe short joint assembled in the step 6 according to the pipe column structure designed in the step 4, and completing the entry of the pipe column into the well.

And 8: the well is opened for production, high-pressure gas in the oil pipe 12 enters the vortex tube 100 through the fluid inlet device 24, and is subjected to strong-rotation turbulent flow movement in the vortex tube 100 and is divided into two flows with opposite flowing directions through the exchange of momentum and heat; the high-temperature fluid flows out of the high-temperature fluid outlet 25, enters the power generation part annular cavity body 29, flows through the outer wall of the temperature difference power generation device 300 to form a high-temperature end of the temperature difference power generation device 300, and finally enters the oil annular cavity body 13 through the first discharge check valve 32; the low-temperature fluid enters the cold fluid channel 301 of the thermoelectric power generation device 300 from the low-temperature fluid outlet 26 to form a low-temperature end of the thermoelectric power generation device 300, then enters the power storage part protective sleeve 27 through the exhausted low-temperature fluid outlet 21 to provide a low-temperature protective environment for the boost regulator 41 and the power storage module 42, and finally enters the oil jacket ring cavity body 13 through the second discharge check valve 33; the thermoelectric generation device 300 generates power under the action of the temperature difference between the inner wall and the outer wall, and transmits the electric energy to the voltage boosting and stabilizing device 41 through the first lead group 51 for voltage boosting and stabilizing, and finally stores the boosted and stabilized electric energy in the electric storage module 42 through the second lead group 52.

And step 9: the downhole electric equipment 43 obtains power supply from the electric storage module 42 through the third lead group 53 according to the power demand, and performs corresponding measurement and control operations.

Example two

The vortex tube 100 is a concurrent flow vortex tube, and the other embodiments are the same as the first embodiment.

EXAMPLE III

The same power generation method steps as the first embodiment are adopted, and the difference is that gas separated from an oil well pump inlet of an oil well with high gas-oil ratio and entering the oil casing annulus 13 provides a downhole high-pressure gas source for the vortex tube 100, the fluid inlet device 24 is communicated with the oil casing annulus 13, and the whole downhole thermoelectric power generation system is positioned at the depth above the working fluid level of the oil well.

Example four

The same power generation method steps as the two embodiments are adopted, and the difference is that gas separated from an oil well pump inlet of an oil well with high gas-oil ratio and entering the oil sleeve annulus 13 provides a downhole high-pressure gas source for the vortex tube 100, the fluid inlet device 24 is communicated with the oil sleeve annulus 13, and the whole downhole thermoelectric power generation system is positioned at the depth above the working fluid level of the oil well.

The connection mode, the installation position and the power generation process of the vortex tube are completely different from those of the underground energy acquisition system in the prior art. The inlet of the vortex tube is connected to the oil tube, only part of fluid in the oil tube enters the vortex tube according to the underground power demand, and the position of the vortex tube is not arranged on a production layer but is optimized through creative work. In addition, cold and hot fluid from the vortex tube directly contacts with the cold and hot ends of the temperature difference power generation device, so that the heat transfer effect is better. In addition, the high-pressure fluid entering the oil pipe is high-pressure fluid from the stratum with the pressure up to several megapascals or even dozens of megapascals, the fluid forms two high-temperature and low-temperature fluids after passing through the vortex tube, the temperature change of dozens of degrees can be obtained within a small scale range of the length of the vortex tube being several meters, the temperature difference required by the thermoelectric power generation device can be provided, and the power generation efficiency is greatly improved. Compared with the prior art that the temperature difference of the produced fluid of the stratum within the range of 100 meters along the flowing direction of the well bore does not change by more than 5 ℃, the invention has outstanding substantive characteristics and remarkable progress.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.