CN115823918B - Annular ultra-long gravity heat pipe system and method for oil and gas well reconstruction - Google Patents
Annular ultra-long gravity heat pipe system and method for oil and gas well reconstruction Download PDFInfo
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- CN115823918B CN115823918B CN202211463319.9A CN202211463319A CN115823918B CN 115823918 B CN115823918 B CN 115823918B CN 202211463319 A CN202211463319 A CN 202211463319A CN 115823918 B CN115823918 B CN 115823918B
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- 239000007788 liquid Substances 0.000 claims description 104
- 238000001704 evaporation Methods 0.000 claims description 33
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- 239000002699 waste material Substances 0.000 claims description 28
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
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- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
The invention relates to an annular ultra-long gravity heat pipe system and a method for oil and gas well reconstruction. Compared with the existing heat pipe formed by only using the oil pipe or only using the production sleeve, the heat exchange space formed by the loop heat pipe is small in cost and capable of achieving better heat exchange efficiency.
Description
Technical Field
The invention relates to a heat pipe technology, in particular to an ultra-long gravity heat pipe device for extracting geothermal energy in a waste oil-gas well, belonging to the field of F28d15/02 heat pipes.
Background
The heat pipe technology is a heat transfer element called a "heat pipe" invented by George Grover (Los Alamos) national laboratory in the United states of Amersham (1963), which fully utilizes the heat conduction principle and the rapid heat transfer property of a phase change medium, and rapidly transfers the heat of a heating object to the outside of a heat source through the heat pipe, and the heat conduction capability of the heat pipe exceeds that of any known metal.
The heat pipe technology is widely applied to the industries of aerospace, military industry and the like before, since the heat pipe technology is introduced into the radiator manufacturing industry, the design thought of the traditional radiator is changed, a single radiating mode of obtaining a better radiating effect by simply relying on a high-air-volume motor is eliminated, the heat pipe technology is adopted to enable the radiator to obtain a satisfactory heat exchanging effect, and a new world of the radiating industry is opened up. At present, the heat pipe is widely applied to various heat exchange equipment, including the nuclear power field, such as the utilization of the waste heat of nuclear power, and the like.
Geothermal energy is valued by the state as a renewable energy source with rich, clean and stable reserves.
Geothermal energy is mainly divided into shallow geothermal energy and deep geothermal energy, wherein the reserve of the deep geothermal energy is 1000 times of that of the shallow geothermal energy, so that the development of the shallow geothermal energy is perfected in China at present, and the development of the deep geothermal energy is relatively less. The technology for developing deep geothermal energy mainly comprises an enhanced geothermal system, a downhole heat exchanger technology and an ultra-long gravity heat pipe technology. The enhanced geothermal system is generally in a double-well or multi-well mode to realize the circulation extraction of deep geothermal energy by fluid working media, and a plurality of problems exist in the current development: (1) the technical difficulty is high and the cost is high; (2) working medium loss disadvantages exist; (3) equipment corrosion-prone structures; (4) environmental disasters are easily caused. Although the underground heat exchanger technology can avoid the problems of working medium loss, equipment corrosion and the like, the working medium changes obviously with depth in the heat exchanger, so that the heat collection effect is poor, and additional pumping work is required to be added in work. The ultralong gravity heat pipe technology transfers heat by utilizing the phase change of the working medium in the heat pipe, the working medium is not in contact with the outside, the problems of working medium loss and equipment corrosion are avoided, and meanwhile, heat can be efficiently transferred from the evaporation section to the condensation section, so that the heat pipe has the advantages of high heat conductivity, excellent temperature uniformity and the like.
In the field of petroleum exploitation at present, with the increasing of petroleum exploitation quantity, the problem that the exploitation quantity of a plurality of oil wells is reduced year by year, so that the number of oil wells scrapped each year is increased year by year, and in the case of winning oil fields, more than ten thousand abandoned wells are accumulated at present. How to recycle the existing waste resources and even realize higher economic benefit becomes a problem to be solved in the current state.
In the calculation of the cost of the ultra-long gravity assisted heat pipe technology, the drilling cost occupies 60 to 80 percent of the total cost. The deep geothermal energy is generally accompanied in the waste oil and gas well, and the drilling process in the waste oil and gas well is finished, so that the waste oil and gas well can be transformed into the ultra-long gravity assisted heat pipe geothermal well only by subsequent repair and overhaul. The waste oil well and the ultra-long gravity heat pipe technology are combined, so that not only is the abundant geothermal resources in the waste well fully utilized, but also the cost of the ultra-long gravity heat pipe technology is effectively reduced, and the double harvest of the recycling of the waste resources and the economic benefit is achieved.
For the ultra-long gravity assisted heat pipe, the design difficulty is mainly in the following aspects: (1) The internal steam flow rate is too high, the pipe diameter is too small, and the heat transfer capacity of the heat pipe is limited by the carrying limit. The flow rate of steam in the heat pipe is gradually increased due to the fact that steam is continuously added, friction force between the steam and the reflux condensate is gradually increased, so that the reflux liquid is carried to the upper portion of the heat pipe, stable two-phase flow is damaged, and heat transfer capacity of the heat pipe is limited. (2) The liquid pool is too deep, the liquid is in a supercooled state, and part of working medium in the heat pipe loses boiling condition, so that a heat transfer dead zone is caused. (3) The steam flow path is too long, the resistance is too large, and the steam in the heat pipe is difficult to flow to the end point. (4) The heat pipe is overlong, the liquid film of the evaporation section can be damaged, and phenomena of cracking and drying occur, so that the heat transfer capacity is reduced.
In the existing patent, the cascade fin gravity heat pipe device (patent application number CN 109029033A) for recovering low-grade waste heat in a shaft can solve the problem of heat pipe carrying limit, but the thermal resistance in the device is mainly concentrated at the connecting part between cascade heat pipes, and the heat is not beneficial to transfer from the bottom of the shaft to the wellhead along with the increase of connection. A heating system (patent application No. CN 112066445A) for exploiting geothermal heat by combining waste oil wells with heat pumps adopts a downhole heat exchanger technology to realize exploitation of deep geothermal heat, however, working media flow in a single-phase flow mode, and as the temperature of the working media increases along with the increase of a flow path, a larger temperature difference is difficult to form, the heat taking capacity is limited, and meanwhile, additional pumping work is required to be added, so that more energy sources are consumed.
There is no method for reforming waste oil-gas well into ultra-long gravity heat pipe geothermal well, and there is no heat pipe between oil pipe and production casing, such as cascade fin gravity heat pipe device (patent application number CN109029033 a) for recovering low grade waste heat in well shaft, and only heat pipe is manufactured between production casings.
Disclosure of Invention
In view of the background and technical problems, the invention provides an ultra-long gravity heat pipe device for extracting geothermal energy in a waste oil-gas well, which solves the problem that the ultra-long gravity heat pipe is limited by a carrying limit, improves heat transfer capacity of the heat pipe, reduces technical cost of the ultra-long gravity heat pipe, and achieves double harvest with energy conservation, environmental protection and economic benefit.
In order to achieve the above purpose, the present invention provides the following technical solutions:
an annular ultra-long gravity assisted heat pipe system reformed by a waste oil and gas well comprises an ultra-long gravity assisted heat pipe matrix, wherein the matrix comprises an oil pipe and a production sleeve, and a space between the oil pipe and the production sleeve forms a heat exchange space of a loop heat pipe, so that an annular space between the oil pipe and the production sleeve is formed.
Preferably, the device comprises a liquid injection valve, a vacuum valve and a perforation, wherein the liquid injection valve is used for adding working medium into the ultra-long gravity heat pipe; the vacuum valve is used for detecting leakage and vacuumizing the overlength gravity heat pipe; the perforation seal is used for plugging the perforation to realize the inner seal of the annular overlength gravity heat pipe.
Preferably, the ultra-long gravity heat pipe comprises an end cover arranged at the upper part, and the end cover comprises a cover body, a liquid injection valve and a vacuum valve.
The method for reforming the waste oil gas well into the annular ultra-long gravity heat pipe comprises the following steps:
1) Selecting an oil pipe and a waste oil-gas well with a production casing being intact;
2) The abandoned oil and gas well is conducted to confirm whether the underground situation is normal or not;
3) After the well is smoothly cleared and no abnormal condition exists in the well, cement slurry is injected into the production casing, and the perforation of the production casing is plugged by pressurization;
4) A packer is put in the joint of the oil pipe and the bottom end of the production casing;
5) Welding an upper end cover of the ultra-long gravity heat pipe above the oil pipe and the production sleeve in a welding mode, so that the tightness of a welding line is ensured;
6) Closing the liquid filling valve, opening the vacuum valve, and checking the tightness of the system by a pressure drop method;
7) Closing the liquid filling valve, opening the vacuum valve, and connecting the vacuum pump with the vacuum valve to vacuumize the ultra-long gravity heat pipe;
8) Closing the vacuum valve, connecting the liquid filling valve with a liquid filling device, and opening the liquid filling valve to perform liquid filling treatment on the ultra-long gravity heat pipe;
9) Closing the liquid filling valve, connecting a heat exchanger or power generation equipment for heat supply and power generation, and simultaneously placing measuring equipment from the intermediate annular structure for detecting the operation condition of the heat pipe.
Preferably, the oil and gas well can be selected by only ensuring good tightness between the oil pipe and the production casing in the process of selecting the oil and gas well, and preferably the intact waste oil and gas well.
Preferably, abandoned oil and gas wells include oil, gas and water wells from abandoned oil and gas fields, as well as vertical, inclined and horizontal wells.
Preferably, the casing perforation seal is produced not only by injecting cement slurry, but also by injecting resin.
Compared with the prior art, the invention has the following advantages:
1. compared with the existing heat pipe formed by only using the oil pipe or only using the production sleeve, the heat exchange space formed by the loop heat pipe is small in cost and capable of achieving better heat exchange efficiency.
2. The invention adopts the coaxial shunt tube to isolate rising steam from descending condensate, reduces the interaction between gas and liquid, and obviously improves the heat transfer limit of the ultra-long gravity heat pipe.
3. According to the invention, the coaxial shunt tubes are subjected to hole opening treatment in the evaporation section and the condensation section, and are matched with the overflow ring and the liquid feeding ring to realize the improvement of heat transfer capacity of the heat pipe, so that the area of a micro-layer liquid film at the bottom of a bubble is increased in the evaporation section, the evaporation time of the micro-layer is prolonged, and the heat transfer in the evaporation section is enhanced; in the condensing section, the countercurrent flow of the steam flow and the liquid film flow is changed into the equidirectional flow of each section, so that the heat transfer of the condensing section is enhanced.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is an enlarged view of a portion of the evaporator end of the present invention;
FIG. 3 is an enlarged view of a portion of the condensing section of the present invention;
FIG. 4 is a schematic illustration of internal gas-liquid flow in accordance with the present invention;
FIG. 5 is a schematic diagram of a preferred ultra-long gravity assisted heat pipe device for extracting geothermal energy from waste oil and gas wells according to the present invention;
fig. 6 is a schematic view of the structure of fig. 5 provided with a gas-liquid split device.
In the figure: the device comprises a 1-liquid injection valve, a 2-heat pipe matrix, a 3-overflow ring, a 4-liquid feeding ring, a 5-coaxial shunt pipe, a 6-evaporation section opening, a 7-perforation seal, an 8-well bottom, a 9-external stratum fracture, a 10-external stratum, a 11-support ring, a 12-condensation section opening, a 13-vacuum valve, a 14-packer, a 15-oil pipe and a 16-end cover.
Detailed Description
The following will make additional description on the technical solution in the embodiment of the present invention with reference to the drawings in the embodiment of the present invention.
As shown in fig. 1, an ultra-long gravity heat pipe device for extracting geothermal energy in a waste oil-gas well comprises a heat pipe substrate 2, wherein a gas-liquid diversion device is arranged in the heat pipe substrate 2, the gas-liquid diversion device comprises a coaxial diversion pipe 5, a support ring 11, an overflow ring 3 and a liquid feeding ring 4, the support ring 11 is arranged between the inner wall of the heat pipe substrate 2 and the outer wall of the diversion pipe 5 of an insulation section and is used for fixing the diversion pipe 5, the overflow ring 3 is arranged between the inner wall of the heat pipe substrate 2 and the diversion pipe 5 of a condensation section, the liquid feeding ring 4 is arranged between the inner wall of the heat pipe substrate 2 and the outer wall of the diversion pipe 5 at the lower part of the overflow ring 3, and channels for flowing down fluid are arranged in the support ring 11, the overflow ring 3 and the liquid feeding ring 4; the coaxial shunt tube 5 is provided with openings in the evaporation section and the condensation section.
The evaporation section of the ultra-long gravity heat pipe absorbs energy of an external stratum to evaporate working media in the pipe, steam flows into the coaxial shunt pipe 5 through the evaporation section opening 6 and flows to the condensation section through the heat insulation section, steam flows into the condensation chamber from the condensation section opening 12 to liquefy and release energy, condensate flows into the outer wall surface of the coaxial shunt pipe through the overflow ring 3 and then flows back to the inner wall surface of the ultra-long gravity heat pipe of the heat insulation section through the liquid feeding ring 4, and then flows to the evaporation section along the wall surface to absorb heat and evaporate again to complete circulation.
Adding a coaxial shunt tube 5 in the evaporation section and carrying out opening treatment to form annular gap boiling between a reflux liquid film of the evaporation section and a liquid pool, wherein after bubbles are generated on the wall surface of the heating section, the coaxial shunt tube 5 plays a role in inhibiting the detachment of the bubbles, so that the bubbles are forced to grow in a cake shape, and after the bubbles touch the opening 6, the bubbles overflow from the hole, so that the area of a micro-layer liquid film at the bottom of the bubbles is increased, the evaporation time of the micro-layer is prolonged, and the heat transfer of the evaporation section is enhanced; steam flows from the evaporation section to the condensation section through the heat insulation section by the coaxial shunt tubes 5, and the shunt tubes 5 block rising steam from contacting with descending condensate liquid so as to reduce interaction between gas and liquid and reduce the influence of carrying limit; the perforated coaxial shunt tube 5 is added in the condensing section and matched with the overflow ring 3 and the liquid feeding ring 4, steam flows upwards along the coaxial shunt tube 5, enters each condensation section through the perforated holes 12 on the coaxial shunt tube 5 to be condensed, each section condensate flows to the outer wall of the coaxial shunt tube 5 in a guiding way through the overflow ring 3, flows downwards along the tube through the circumferential annular gap, flows back to the position of the liquid feeding ring 4 to the inner wall surface of the ultra-long gravity heat pipe matrix 2, the countercurrent flow of the steam flow and the liquid film flow is changed into the equidirectional flow of each section, the shearing force between the gas and the liquid is obviously reduced, the carrying limit of the heat pipe is improved, and the heat transfer of the condensing section is enhanced.
The invention adopts the coaxial shunt tube to isolate rising steam from descending condensate, reduces the interaction between gas and liquid, and obviously improves the heat transfer limit of the ultra-long gravity heat pipe; according to the invention, the coaxial shunt tubes are subjected to hole opening treatment in the evaporation section and the condensation section, and are matched with the overflow ring and the liquid feeding ring to realize the improvement of heat transfer capacity of the heat pipe, so that the area of a micro-layer liquid film at the bottom of a bubble is increased in the evaporation section, the evaporation time of the micro-layer is prolonged, and the heat transfer in the evaporation section is enhanced; in the condensing section, the countercurrent flow of the steam flow and the liquid film flow is changed into the equidirectional flow of each section, so that the heat transfer of the condensing section is enhanced.
Preferably, the overflow ring 3 is disposed obliquely upward from the outer wall of the shunt tube to the inner wall of the heat pipe substrate, and the liquid feed ring 4 is disposed obliquely downward from the outer wall of the shunt tube to the inner wall of the heat pipe. As the thermosiphon single tube transfer power increases, the reflux condensate film increases in thickness, which increases the condensation thermal resistance. An overflow ring 3 is arranged for reducing the thickness of the liquid film, and is upwards inclined from the outer wall of the shunt pipe to the inner wall of the heat pipe matrix, condensate of each condensation section can be guided to the outer wall surface of the coaxial shunt pipe 5 along the overflow ring 3, and the gas-liquid flowing direction is changed from countercurrent to concurrent, so that the thickness of the liquid film of the condensation section is reduced, and the heat exchange capacity of the condensation section is improved; in order to enable the condensate liquid separated from the condensation section to heat up rapidly and reduce heat exchange loss of the condensate liquid and steam in the shunt tube, a liquid feeding ring 4 which is inclined downwards from the outer wall of the shunt tube to the inner wall of the heat pipe is arranged, the condensate liquid flowing along the outer wall surface of the coaxial shunt tube 5 is guided to the inner wall surface of the heat pipe, and the condensate liquid flows to the evaporation section along the inner wall surface of the heat pipe, so that a faster heating cycle process is realized, and meanwhile, the heat exchange of the condensate liquid and steam in the shunt tube 5 is reduced, and the steam loss is reduced.
Preferably, the passages for fluid to flow down in the support ring 11 and the liquid feeding ring 4 are arranged near the inner wall of the heat pipe. Through so setting up, can make the liquid of backward flow keep away from the shunt tubes, avoid carrying out the heat transfer with the steam in the shunt tubes, simultaneously along with downwardly flowing, geothermal energy also can increase gradually, also can absorb the heat of heat pipe inner wall.
Preferably, the channels in the overflow ring for fluid to flow down are arranged closer to the inner wall of the heat pipe along the height direction from top to bottom. Because the higher the steam temperature is, the more the steam quantity is, the insufficient heat exchange problem exists in the external heat exchange process, and the formed liquid temperature is also high, so that the superheated steam coming out of the overflow ring drives the high-temperature liquid to continue to be fully mixed through being close to the overflow ring, and more new steam is formed, so that the heat exchange is performed with the external cold source again, and the heat exchange efficiency is improved. The lower the liquid temperature is, the more away from the steam, reducing heat exchange with the steam and causing heat source waste.
Preferably, the distance between the channel for fluid flowing down in the overflow ring and the inner wall of the heat pipe is changed more and more along the height direction from top to bottom. The heat exchange efficiency can be further improved and the heat can be fully utilized by a large number of numerical simulation and experiments.
Preferably, the distribution density of the openings of the evaporation section is greater along the height from top to bottom. Because the steam generally flows upwards at first, through setting up trompil size, avoid steam to distribute in a large number on upper portion for steam evenly distributes in whole direction of height, thereby reaches even heat transfer, improves heat transfer efficiency.
Preferably, the distribution density of the openings of the evaporation section is increased along the height from top to bottom. The heat exchange efficiency can be further improved by a large number of numerical simulations and experiments, uniform heat exchange is achieved, and the heat exchange efficiency is improved.
Preferably, the upper part of the heat pipe substrate is provided with a liquid injection valve 1 and a vacuum valve 13, the vacuum valve 13 is used for vacuumizing the heat pipe, and the liquid injection valve 1 is used for injecting liquid into the heat pipe.
Preferably, the ultra-long gravity heat pipe substrate is reformed by a waste oil and gas well production sleeve, and the perforation is plugged by injecting cement or resin to form perforation seal 7, so that isolation and sealing with external stratum cracks 9 are realized.
Preferably, the coaxial shunt tube is subjected to heat-insulating layer adding treatment comprising an evaporation section, a condensation section and a heat-insulating section so as to reduce the loss of steam in the flowing process.
Preferably, abandoned oil and gas wells include oil, gas and water wells from which the oil and gas field is abandoned, as well as vertical, inclined and horizontal wells.
Preferably, the holes on the coaxial shunt tube can be round holes, triangular holes, square holes and other polygonal holes, and the holes are distributed in the circumferential direction of the coaxial shunt tube. From the viewpoints of heat exchange efficiency and pore opening cost, the aperture ratio is preferably 30 to 40%, and more preferably 33%.
Preferably, the inclination angle of the overflow ring and the liquid feed ring is 10 to 40 °. By setting the inclination angles for the overflow ring and the liquid feeding ring, the overflow ring guides condensate liquid of each condensation section to the outer wall surface of the shunt pipe so as to reduce the thickness of a liquid film of the condensation section to realize heat transfer enhancement, change the reverse flow of gas and liquid into forward flow, reduce the flow resistance and improve the carrying limit; the liquid feeding ring guides the condensate flowing along the shunt tube to flow back to the inner wall surface of the heat pipe, so that the temperature is quickly raised in the process of flowing from the heat insulation section to the evaporation section, the heat exchange between the condensate and steam in the shunt tube is reduced, the faster circulation is realized, and the steam loss is reduced.
Preferably, the vacuum degree of the ultra-long gravity heat pipe is 10 < -1 > to 10 < -6 > Pa.
Preferably, the liquid filling rate of the ultra-long gravity heat pipe is 10-40%.
Preferably, the working medium in the ultra-long gravity heat pipe is an organic working medium or an inorganic working medium such as deionized water, acetone, ethanol and the like.
Compared with the prior art, the invention has the advantages that the ultra-long gravity heat pipe heat-taking mode is adopted, compared with the underground heat exchanger mode, the gas-liquid two-phase flow is used for replacing the traditional single-phase flow, the collected energy is stored in the form of latent heat, the higher heat transfer temperature difference is realized, and the heat transfer capacity is enhanced; the invention adopts the concentric shunt tube 5 to isolate rising steam from descending condensate, reduces the interaction between gas and liquid, and obviously improves the heat transfer limit of the ultra-long gravity heat pipe; according to the invention, the coaxial shunt tube 5 is provided with holes 6 and 12 in the evaporation section and the condensation section, and is matched with the overflow ring 3 and the liquid feeding ring 4 to realize the improvement of heat transfer capacity of the heat pipe, so that the area of a micro-layer liquid film at the bubble bottom is increased in the evaporation section, the evaporation time of the micro-layer is prolonged, and the heat transfer of the evaporation section is enhanced; in the condensing section, the countercurrent flow of the steam flow and the liquid film flow is changed into the equidirectional flow of each section, so that the heat transfer of the condensing section is enhanced.
The invention further provides a method for transforming the waste oil gas well into the annular ultra-long gravity heat pipe and the annular ultra-long gravity heat pipe transformed by the waste oil gas well.
The method for reforming the waste oil gas well into the annular ultra-long gravity heat pipe comprises the following steps:
1) Selecting an oil pipe and a waste oil-gas well with a production casing being intact;
2) The abandoned oil and gas well is conducted to confirm whether the underground situation is normal or not;
3) After the well is smoothly cleared and no abnormal condition exists in the well, cement slurry is injected into the production casing, and the perforation of the production casing is plugged by pressurization;
4) A packer is put in the joint of the oil pipe and the bottom end of the production casing;
5) Welding an upper end cover of the ultra-long gravity heat pipe above the oil pipe and the production sleeve in a welding mode, so that the tightness of a welding line is ensured;
6) Closing the liquid filling valve, opening the vacuum valve, and checking the tightness of the system by a pressure drop method;
7) Closing the liquid filling valve, opening the vacuum valve, and connecting the vacuum pump with the vacuum valve to vacuumize the ultra-long gravity heat pipe;
8) Closing the vacuum valve, connecting the liquid filling valve with a liquid filling device, and opening the liquid filling valve to perform liquid filling treatment on the ultra-long gravity heat pipe;
9) Closing the liquid filling valve, connecting a heat exchanger or power generation equipment for heat supply and power generation, and simultaneously placing measuring equipment from the intermediate annular structure for detecting the operation condition of the heat pipe.
Furthermore, in the process of selecting the oil gas well, the oil pipe and the production casing can be selected only by ensuring good tightness, and the intact waste oil gas well is preferred.
Further, the abandoned oil and gas wells in the above proposal include oil and gas fields abandoned oil and gas wells, gas wells and water wells, and also include vertical wells, inclined wells and horizontal wells.
Further, the method of producing the casing perforation seal in the above scheme can adopt a method of injecting cement slurry, and also comprises a method of injecting resin.
Compared with the existing heat pipe formed by only using the oil pipe or only using the production sleeve, the heat exchange space formed by the loop heat pipe is small in cost and capable of achieving better heat exchange efficiency. Because the main heat source position is the production sleeve, the production sleeve is fully utilized, the space of the heat pipe and unnecessary heat exchange areas with low efficiency, such as the space in the oil pipe, are reduced, the high heat exchange area is fully utilized, and the high-efficiency heat exchange can be realized under the condition that the geothermal energy is unchanged.
As shown in fig. 5, the above waste oil-gas well is modified into an annular ultra-long gravity assisted heat pipe system structure, which comprises a liquid injection valve 1, an ultra-long gravity assisted heat pipe substrate 2, a perforation seal 7, a well bottom 8, an external stratum fracture 9, an external stratum 10, a vacuum valve 13, a packer 14, an oil pipe 15 and an end cover 16. The liquid injection valve 1 is used for adding working medium into the ultra-long gravity heat pipe; the vacuum valve 13 is used for detecting leakage and vacuumizing the ultra-long gravity heat pipe; the perforation seal 7 is used for plugging perforation to realize the inner seal of the annular ultra-long gravity heat pipe. The heat pipe base 2 comprises an oil pipe and a production casing, the space between the oil pipe and the production casing forming the heat exchanging space of the loop heat pipe, thereby forming an annular space between an inner ring (oil pipe) and an outer ring (production casing).
The ultra-long gravity heat pipe absorbs heat in an external stratum 10 and an external stratum crack 9 in an evaporation section to enable working medium in a heat pipe cavity to be gasified, the gasified working medium flows upwards along the inside of the heat pipe, the condensation section at the top end of the heat pipe is liquefied and releases heat, the liquefied working medium flows back to the evaporation section along the wall surface of the heat pipe to be gasified continuously to complete circulation, and geothermal energy in a deep stratum is extracted for heat extraction and power generation.
The end cover 16 of the ultra-long gravity heat pipe mainly comprises a cover body, a liquid injection valve 1 and a vacuum valve 13.
As shown in fig. 5, selecting a waste oil-gas well with intact oil pipe and production casing, performing well dredging treatment, injecting cement slurry into the production casing after ensuring that the underground condition is normal, and realizing perforation sealing 7 by pressurization; welding an end cover 16 at the top end of the oil pipe 15 and the top end of the production sleeve, closing the liquid injection valve 1, opening the vacuum valve 13, checking the tightness of the ultra-long gravity heat pipe in a pressurizing mode, and connecting a vacuum pump for vacuumizing after the tightness is ensured; closing the vacuum valve 13, opening the liquid injection valve 1, and connecting a liquid injection device to inject working medium into the ultra-long gravity heat pipe; the liquid filling valve 1 is closed, a heat exchanger or a power generation device is connected for heat supply and power generation, and meanwhile, a measuring device can be placed in the middle annular structure for detecting the operation condition of the heat pipe.
Preferably, the heat pipe of fig. 5 is also provided with the vapor-liquid diversion device of fig. 1 comprising an oil pipe 15 and a production casing, a coaxial diversion pipe 5, a support ring 11, an overflow ring 3 and a liquid feed ring 4. The two supporting rings 11 are respectively arranged between the inner wall of the production sleeve of the heat insulation section and the outer wall of the shunt tube 5 and between the inner wall of the shunt tube 5 and the outer wall of the oil tube 15, and are used for fixing the shunt tube 5, the overflow ring 3 is arranged between the inner wall of the production sleeve of the condensation section and the shunt tube 5, the liquid feeding ring 4 is arranged between the inner wall of the production sleeve at the lower part of the overflow ring 3 and the outer wall of the shunt tube 5, and channels for fluid to flow down are arranged in the supporting rings 11, the overflow ring 3 and the liquid feeding ring 4; the coaxial shunt tube 5 is provided with openings in the evaporation section and the condensation section.
Preferably, the overflow ring 3 is arranged obliquely upwards from the outer wall of the shunt tube, and the liquid feeding ring 4 is arranged obliquely downwards from the outer wall of the shunt tube.
The remaining technical features are the same as those described in the previous embodiments, and the contents of the embodiments of fig. 1 to 4 will not be described in detail.
The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be construed to be included in the scope of the present invention.
Claims (6)
1. An annular ultra-long gravity assisted heat pipe system reformed by a waste oil and gas well comprises an ultra-long gravity assisted heat pipe matrix, wherein the matrix comprises an oil pipe and a production sleeve, and a space between the oil pipe and the production sleeve forms a heat exchange space of a loop heat pipe so as to form an annular space between the oil pipe and the production sleeve; the system comprises a coaxial shunt tube, a supporting ring, an overflow ring and a liquid feeding ring; the two support rings are respectively arranged between the inner wall of the production sleeve of the heat insulation section and the outer wall of the shunt tube and between the inner wall of the shunt tube and the outer wall of the oil pipe, and are used for fixing the shunt tube, the overflow ring is arranged between the inner wall of the production sleeve of the condensation section and the shunt tube, the liquid feeding ring is arranged between the inner wall of the production sleeve at the lower part of the overflow ring and the outer wall of the shunt tube, and the support ring, the overflow ring and the liquid feeding ring are provided with channels for fluid to flow down; the coaxial shunt tube is provided with openings in the evaporation section and the condensation section; the overflow ring is obliquely arranged upwards from the outer wall of the shunt tube, and the liquid feeding ring is obliquely arranged downwards from the outer wall of the shunt tube; along the height from top to bottom, the channel in the overflow ring for fluid to flow down is arranged closer to the inner wall of the heat pipe.
2. The gravity assisted heat pipe system according to claim 1 comprising a liquid injection valve, a vacuum valve, a perforation, the liquid injection valve being adapted to add a working medium into the ultra-long gravity assisted heat pipe; the vacuum valve is used for detecting leakage and vacuumizing the overlength gravity heat pipe; the perforation seal is used for plugging the perforation to realize the inner seal of the annular overlength gravity heat pipe.
3. The gravity assisted heat pipe system of claim 1 wherein the ultra-long gravity assisted heat pipe includes an upper end cap comprising a cap body, a liquid injection valve, and a vacuum valve.
4. A method of retrofitting a gravity assisted heat pipe system according to any of claims 1 to 3:
1) Selecting an oil pipe and a waste oil-gas well with a production casing being intact;
2) The abandoned oil and gas well is conducted to confirm whether the underground situation is normal or not;
3) After the well is smoothly cleared and no abnormal condition exists in the well, cement slurry is injected into the production casing, and the perforation of the production casing is plugged by pressurization;
4) A packer is put in the joint of the oil pipe and the bottom end of the production casing;
5) Welding an upper end cover of the ultra-long gravity heat pipe above the oil pipe and the production sleeve in a welding mode, so that the tightness of a welding line is ensured;
6) Closing the liquid filling valve, opening the vacuum valve, and checking the tightness of the system by a pressure drop method;
7) Closing the liquid filling valve, opening the vacuum valve, and connecting the vacuum pump with the vacuum valve to vacuumize the ultra-long gravity heat pipe;
8) Closing the vacuum valve, connecting the liquid filling valve with a liquid filling device, and opening the liquid filling valve to perform liquid filling treatment on the ultra-long gravity heat pipe;
9) Closing the liquid filling valve, connecting a heat exchanger or power generation equipment for heat supply and power generation, and simultaneously placing measuring equipment from the intermediate annular structure for detecting the operation condition of the heat pipe.
5. The method of claim 4, wherein the oil and gas well is selected by only ensuring good tightness between the oil pipe and the production casing.
6. The method of claim 4, wherein the abandoned oil and gas wells comprise abandoned oil, gas and water wells of an oil and gas field and comprise vertical, inclined and horizontal wells.
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