Drilling fluid circulating cooling system and cooling method

Abstract

The invention provides a drilling fluid circulating cooling system and method, and the system comprises a drilling fluid circulating pipeline which is communicated with a shaft; the absorption heat pump comprises a generator, an absorber, a condenser and an evaporator, a first medium circulating pipeline is connected between the generator and the absorber, a first steam pipeline is connected between the generator and the condenser, a condensate water pipeline is connected between the condenser and the evaporator, and a second steam pipeline is connected between the evaporator and the absorber. The cooling water pipeline sequentially penetrates through the absorber and the condenser in the water flow direction, and a first heat exchanger is arranged at the outlet end of the cooling water pipeline; the high-temperature end of the second medium circulating pipeline is arranged in the evaporator, and the low-temperature end of the second medium circulating pipeline is connected with a second heat exchanger; and the drilling fluid circulating pipeline is provided with a first cooling section, a second cooling section and a third cooling section which are respectively arranged in the generator, the first heat exchanger and the second heat exchanger. The multi-stage cooling of the drilling fluid is realized through the absorption heat pump, so that the temperature of the drilling fluid can be greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling technology, and in particular to a drilling fluid circulation cooling system and cooling method capable of performing multi-stage cooling of drilling fluid to achieve significant temperature reduction. Background Technology

[0002] Drilling fluid, often referred to as the "blood" of oil drilling, plays a crucial role in drilling operations, carrying cuttings back from the well and maintaining a stable downhole environment temperature. It is an indispensable technical support in drilling engineering and a key factor determining the depth of oil and gas resource development. Deepwater drilling fluid technology represents the forefront of the drilling fluid field and is considered the "golden key" to solving challenging deep-sea drilling problems. The sustained high temperature of the drilling fluid after circulation deteriorates mud properties, affects the lifespan of downhole drilling tools and testing equipment, reduces drilling speed, and threatens drilling safety. Therefore, timely cooling of the drilling fluid to maintain a suitable temperature is essential for drilling safety during the drilling process.

[0003] Currently, numerous studies and applications have been conducted on drilling fluid cooling. Existing technologies include first cooling the drilling fluid with a refrigerant, and then cooling the refrigerant with a lithium bromide refrigeration system. However, this method is only suitable for cooling drilling fluids with small temperature differences, and can only be performed once. It is also suitable for situations where the temperature difference before and after cooling is small. Although refrigerant cooling can be unaffected by ambient temperature, the temperature difference before and after cooling is small, around 40 degrees Celsius, and it is not applicable for large temperature differences. Existing technologies also utilize different cooling media to achieve multi-stage cooling of drilling fluids. However, since there is no clear correlation between various cooling media (air cooling, water cooling, etc.), a separate cooling device is required for each stage of cooling, resulting in relatively high costs.

[0004] Therefore, there is an urgent need to study a new drilling fluid circulation cooling system and cooling method to overcome the existing problems. Summary of the Invention

[0005] The purpose of this invention is to provide a drilling fluid circulation cooling system and cooling method, which achieves multi-stage cooling of the drilling fluid through an absorption heat pump, thereby enabling a significant reduction in the temperature of the drilling fluid.

[0006] On one hand, the present invention provides a drilling fluid circulation cooling system, comprising:

[0007] A drilling fluid circulation pipeline is connected to the wellbore, allowing drilling fluid in the wellbore to enter the drilling fluid circulation pipeline and flow back into the wellbore;

[0008] An absorption heat pump includes a generator, an absorber, a condenser, and an evaporator. A first medium circulation pipe is connected between the generator and the absorber. A first steam pipe is connected between the generator and the condenser. A condensate pipe is connected between the condenser and the evaporator. A second steam pipe is connected between the evaporator and the absorber.

[0009] A cooling water pipe passes through the absorber and the condenser in sequence along the water flow direction, and a first heat exchanger is provided at the outlet end of the cooling water pipe;

[0010] The second medium circulation pipe has a high-temperature end located inside the evaporator and a low-temperature end connected to a second heat exchanger.

[0011] The drilling fluid circulation pipeline has a first cooling section, a second cooling section, and a third cooling section respectively located in the generator, the first heat exchanger, and the second heat exchanger.

[0012] The drilling fluid circulating cooling system of the present invention adopts a three-stage cooling method. The drilling fluid flows through the generator (where it undergoes primary cooling) to drive the absorption heat pump. Then, the drilling fluid exchanges heat with cooling water through the first heat exchanger (performing secondary cooling). Finally, it exchanges heat with the refrigerant through the second heat exchanger (performing tertiary cooling) and is then reinjected into the wellbore as needed.

[0013] The drilling fluid circulating cooling system of this invention uses drilling fluid waste heat to drive an absorption heat pump, which consumes little electricity; it can achieve large temperature difference heat exchange of drilling fluid, unaffected by ambient temperature, and can achieve a temperature difference of about 100 degrees Celsius before and after cooling, with the final temperature of the drilling fluid after cooling being stable at about 25 degrees Celsius; the drilling fluid cooling process adopts a closed heat exchange, and the cooling effect is less affected by the environment, resulting in excellent energy saving and emission reduction effects.

[0014] In a preferred embodiment of the present invention, the first medium circulating in the first medium circulation pipe is a lithium bromide solution or ammonia.

[0015] In this embodiment, lithium bromide solution or ammonia is used as the first medium. The lithium bromide solution can circulate between the generator and the absorber to achieve heat conversion, thereby providing primary cooling for the drilling fluid flowing through the generator; ammonia can also achieve the above function.

[0016] In a preferred embodiment of the present invention, the first medium circulation pipeline includes a dilute solution pipeline and a concentrated solution pipeline both connected between the generator and the absorber, and the cooling water pipeline has a first heating section disposed within the absorber.

[0017] The dilute lithium bromide solution in the dilute solution pipeline flows to the generator and is sprayed onto the first cooling section. The dilute lithium bromide solution heats up and generates water vapor, while simultaneously forming a concentrated lithium bromide solution.

[0018] The concentrated lithium bromide solution in the concentrated solution pipeline flows to the absorber and is sprayed onto the first heating section. The concentrated lithium bromide solution exchanges heat, cools down, and absorbs water vapor, while simultaneously forming a concentrated lithium bromide solution.

[0019] In this embodiment, the lithium bromide solution is circulated through dilute solution pipes and concentrated solution pipes, and the conversion between dilute lithium bromide solution and concentrated lithium bromide solution is realized at the same time, thereby absorbing water vapor from the evaporator in real time and supplying water vapor to the condenser in real time.

[0020] In a preferred embodiment of the present invention, a third heat exchanger is provided between the dilute solution pipeline and the concentrated solution pipeline.

[0021] In this embodiment, the third heat exchanger enables heat exchange between the concentrated lithium bromide solution and the dilute lithium bromide solution, thereby improving the energy utilization efficiency of the entire system.

[0022] In a preferred embodiment of the present invention, the cooling water pipe further includes a second heating section disposed within the condenser. The water vapor generated in the generator enters the condenser through the first steam pipe and is sprayed onto the second heating section, where the water vapor undergoes heat exchange and liquefies into condensate.

[0023] In this embodiment, the cooling water pipe extends into the condenser to form a second heating section, thereby realizing heat exchange between the cooling water and the water vapor entering the condenser, causing the water vapor to liquefy into condensate, and then supplying condensate to the evaporator for cooling the high-temperature heat exchange medium.

[0024] In a preferred embodiment of the present invention, the water vapor generated in the condenser enters the evaporator through the condensate pipe and is sprayed onto the high-temperature end of the second medium circulation pipe, where the condensate is vaporized into water vapor through heat exchange.

[0025] The water vapor generated in the evaporator enters the absorber through the second steam pipe and is absorbed by the dilute lithium bromide solution to form the concentrated lithium bromide solution.

[0026] In this embodiment, the high-temperature end of the second medium circulation pipe extends into the evaporator to form a high-temperature end, thereby realizing heat exchange between the second medium and the condensate entering the evaporator, so that the condensate vaporizes into water vapor, and can then supply water vapor to the absorber for mixing with the dilute lithium bromide solution to produce a concentrated lithium bromide solution.

[0027] In a preferred embodiment of the present invention, the cooling water pipe further includes a third heating section disposed within the first heat exchanger, the third heating section being capable of exchanging heat with the second cooling section.

[0028] In this embodiment, the third heating section of the cooling water pipeline and the second cooling section of the drilling fluid circulation pipeline exchange heat in the first heat exchanger, thereby achieving secondary cooling of the drilling fluid.

[0029] In a preferred embodiment of the present invention, the second heat exchanger includes a drilling fluid storage tank disposed on the drilling fluid circulation pipeline, a heat exchange medium storage tank disposed on the second medium circulation pipeline, and a heat pipe connecting the drilling fluid storage tank and the heat exchange medium storage tank.

[0030] The drilling fluid storage tank forms the third cooling section on the drilling fluid circulation pipeline.

[0031] In this embodiment, the heat pipe connected between the drilling tank and the heat exchange medium tank enables heat exchange between the drilling fluid and the heat exchange medium, thereby achieving three-stage cooling of the drilling fluid.

[0032] In a preferred embodiment of the present invention, the heat exchange medium storage tank forms the low-temperature end, and the end of the second medium circulation pipe away from the heat exchange medium storage tank passes through the evaporator to form the high-temperature end.

[0033] In this embodiment, the heat exchange medium storage tank of the second medium circulation pipeline is connected, and the heat exchange medium in the pipeline circulates in the heat exchange medium storage tank and the evaporator to achieve heat transfer.

[0034] In a preferred embodiment of the present invention, a water supply pipe is connected to the cooling water pipe between the condenser and the first heat exchanger, and the water supply pipe can supply cooling water to the cooling water pipe.

[0035] In this embodiment, cooling water is added to the cooling water pipe through the water supply pipe, which increases the flow rate of cooling water entering the first heat exchanger. The temperature of the drilling fluid flowing out of the first heat exchanger is lower (the temperature is even lower after the second heat exchange). When the drilling fluid enters the second heat exchanger for tertiary cooling, the required heat exchange is relatively small, thereby achieving a surplus of heat exchange medium (coolant) in the second heat exchanger.

[0036] In a preferred embodiment of the present invention, a drain pipe is connected to the cooling water pipe between the condenser and the first heat exchanger, and the drain pipe can lead out the cooling water in the cooling water pipe.

[0037] In this embodiment, a portion of the cooling water in the cooling water pipe is discharged through the drain pipe, thereby reducing the flow rate of cooling water entering the first heat exchanger. This results in a higher temperature of the cooling water after heat exchange with the drilling fluid in the first heat exchanger, reaching over 50 degrees Celsius. Cooling water at this temperature can be supplied to users for heating or domestic water use.

[0038] In a preferred embodiment of the present invention, the drilling fluid circulation cooling system further includes a sedimentation tank disposed on the drilling fluid circulation pipeline, and the sedimentation tank is located upstream of the first cooling section along the flow direction of the drilling fluid.

[0039] In this embodiment, the sedimentation tank can separate and settle the drilling fluid, preventing solid impurities in it from circulating with the drilling fluid in the drilling fluid circulation pipeline, which could lead to pipeline damage or blockage. Furthermore, solid impurities carried in the drilling fluid can also increase the power and energy consumption required for the drilling fluid circulation.

[0040] In a preferred embodiment of the present invention, the drilling fluid circulation pipeline, the first medium circulation pipeline, and the second medium circulation pipeline are all equipped with liquid pumps for driving fluid flow.

[0041] In this embodiment, the liquid pump can provide power for the circulation of drilling fluid, the circulation of the first medium (lithium bromide solution), and the circulation of the second medium (coolant).

[0042] On the other hand, the present invention also provides a drilling fluid circulation cooling method, wherein the method is implemented using the drilling fluid circulation cooling system described above, and the drilling fluid circulation cooling method includes:

[0043] The drilling fluid in the wellbore is transported to a generator in an absorption heat pump for primary cooling, where the drilling fluid exchanges heat with a first medium to lower its temperature.

[0044] The drilling fluid after primary cooling is transported to the first heat exchanger for secondary cooling, where the drilling fluid exchanges heat with cooling water to lower its temperature.

[0045] The drilling fluid after secondary cooling is transported to the second heat exchanger for tertiary cooling, where the drilling fluid exchanges heat with the heat exchange medium to cool down.

[0046] The cooling water is heated by heat exchange in the absorber and cooler of the absorption heat pump before being introduced into the first heat exchanger, and the heat exchange medium is cooled by heat exchange in the evaporator of the absorption heat pump before being introduced into the second heat exchanger.

[0047] The drilling fluid circulation cooling method described in this invention employs a three-stage cooling approach. Drilling fluid flows through a generator (where it undergoes primary cooling) to drive an absorption heat pump. Subsequently, the drilling fluid exchanges heat with cooling water through a first heat exchanger (secondary cooling), and finally exchanges heat with a refrigerant through a second heat exchanger (tertiary cooling) before being reinjected into the well as needed. Utilizing residual heat from the drilling fluid to drive the absorption heat pump results in low power consumption. It enables large temperature difference heat exchange of the drilling fluid, unaffected by ambient temperature, achieving a temperature difference of up to 100 degrees Celsius before and after cooling, with the final temperature of the cooled drilling fluid remaining stable at approximately 25 degrees Celsius. The closed-loop heat exchange process minimizes environmental impact on cooling performance, resulting in excellent energy-saving and emission-reduction effects.

[0048] In a preferred embodiment of the present invention, before the step of conveying the drilling fluid in the wellbore to the generator in the absorption heat pump for primary cooling, the method further includes: conveying the drilling fluid in the wellbore to a sedimentation tank for sedimentation.

[0049] In this embodiment, the drilling fluid is precipitated and separated to prevent solid impurities from circulating with the drilling fluid in the drilling fluid circulation pipeline, which could lead to pipeline damage or blockage. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0051] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0052] Figure 1 This is a schematic diagram of the drilling fluid circulation cooling system described in this invention.

[0053] Explanation of reference numerals in the attached figures:

[0054] 10. Well shaft; 11. Sedimentation tank; 12. First liquid pump; 13. Second liquid pump;

[0055] 20. Drilling fluid circulation pipeline; 21. First cooling section; 22. Second cooling section; 23. Third cooling section;

[0056] 30. Cooling water pipes; 31. First heating section; 32. Second heating section; 33. Third heating section;

[0057] 40. Absorption heat pump; 41. Generator; 42. Absorber; 43. Condenser; 44. Evaporator; 45. First medium circulation pipeline; 451. Dilute solution pipeline; 452. Concentrated solution pipeline; 453. Third heat exchanger; 46. First steam pipeline; 47. Second steam pipeline; 48. Condensate pipeline;

[0058] 50. Second medium circulation pipeline; 51. Evaporation heat exchange section;

[0059] 60. First heat exchanger; 61. Second heat exchanger; 611. Drilling fluid storage tank; 612. Heat exchange medium storage tank; 613. Heat pipe. Detailed Implementation

[0060] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0061] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0063] Implementation Method 1:

[0064] like Figure 1As shown, the present invention provides a drilling fluid circulation cooling system, comprising: a drilling fluid circulation pipe 20 connected to a wellbore 10, wherein drilling fluid in the wellbore 10 can enter the drilling fluid circulation pipe 20 and flow back into the wellbore 10; an absorption heat pump 40, comprising a generator 41, an absorber 42, a condenser 43, and an evaporator 44, wherein a first medium circulation pipe 45 connects the generator 41 and the absorber 42, a first steam pipe 46 connects the generator 41 and the condenser 43, a condensate water pipe 48 connects the condenser 43 and the evaporator 44, and the evaporator 44 and the absorber 42 are connected by a first medium circulation pipe 45. A second steam pipe 47 is connected between the absorbers 42; a cooling water pipe 30 passes through the absorber 42 and the condenser 43 in sequence along the water flow direction, and a first heat exchanger 60 is provided at the outlet end of the cooling water pipe 30; a second medium circulation pipe 50 is provided at the high temperature end of the second medium circulation pipe 50 inside the evaporator 44, and a second heat exchanger 61 is connected at the low temperature end of the second medium circulation pipe 50; the drilling fluid circulation pipe 20 has a first cooling section 21, a second cooling section 22 and a third cooling section 23 respectively provided inside the generator 41, the first heat exchanger 60 and the second heat exchanger 61.

[0065] The drilling fluid circulating cooling system of the present invention adopts a three-stage cooling method. The drilling fluid flows through the generator 41 (where it undergoes primary cooling) to drive the absorption heat pump 40 to work. Then, the drilling fluid exchanges heat with the cooling water through the first heat exchanger 60 (performing secondary cooling). Finally, it exchanges heat with the refrigerant through the second heat exchanger 61 (performing tertiary cooling) and is then reinjected into the wellbore 10 as needed.

[0066] The drilling fluid circulation cooling system of this invention uses a drilling fluid waste heat to drive an absorption heat pump 40, which consumes little electricity; it can achieve large temperature difference heat exchange of drilling fluid, unaffected by ambient temperature, and can achieve a temperature difference of about 100 degrees Celsius before and after cooling, with the final temperature of the drilling fluid after cooling being stable at about 25 degrees Celsius; the drilling fluid cooling process adopts a closed heat exchange, and the cooling effect is less affected by the environment, resulting in excellent energy saving and emission reduction effects.

[0067] The structure of each unit of the drilling fluid circulation cooling system described in this invention and the connection relationship between them will be described in detail below.

[0068] First, such as Figure 1 As shown, the drilling fluid circulation pipe 20 is a liquid transport pipe used for drilling fluid cooling. Both ends of the pipe are located inside the wellbore 10. The drilling fluid inside the wellbore 10 can enter the drilling fluid circulation pipe 20 from the inlet and then flow out of the wellbore 10. The drilling fluid is cooled by heat exchange when it flows through the part of the drilling fluid circulation pipe 20 located outside the wellbore 10, and then flows back into the wellbore 10 through the outlet of the drilling fluid circulation pipe 20.

[0069] Better, such as Figure 1 As shown, a first pump 12 is installed on the drilling fluid circulation pipeline 20, which provides power for the flow of drilling fluid in the drilling fluid circulation pipeline 20.

[0070] Secondly, the absorption heat pump 40 refers to a heat exchange unit consisting of a generator 41, an absorber 42, a condenser 43, and an evaporator 44, wherein the first medium can circulate between the generator 41 and the absorber 42 through the first medium circulation pipe 45, and water or water vapor can circulate between the generator 41, the absorber 42, the condenser 43, and the evaporator 44.

[0071] Among them, generator 41 is a closed chamber that can realize heat exchange and temperature rise of solution and generate water vapor; absorber 42 is a closed chamber that can realize heat exchange and temperature rise of solution and absorb water vapor; condenser 43 is a closed chamber that can realize condensation and liquefaction of water vapor; evaporator 44 is a closed chamber that can realize evaporation and vaporization of liquid water.

[0072] Preferably, the first medium circulating in the first medium circulation pipe 45 is a lithium bromide solution or ammonia. The lithium bromide solution, as the first medium, can circulate between the generator 41 and the absorber 42 to achieve heat conversion, thereby providing primary cooling for the drilling fluid flowing through the generator 41. Ammonia can also achieve the above function, but its performance as a working medium is lower than that of lithium bromide solution, resulting in a relatively poor heat exchange conversion effect.

[0073] Of course, the first medium described in this invention can also be a calcium chloride solution, a lithium bromide-lithium chloride solution, or other types of organic solutions, but the above-mentioned working fluids have problems such as poor performance, strong corrosiveness, and high cost, making them difficult to use on a large scale. For ease of explanation, the following description uses a lithium bromide solution as the first medium. The heat exchange conversion process of other types of solutions is basically the same as the conversion process of the lithium bromide solution described below.

[0074] Specifically, such as Figure 1 As shown, the drilling fluid circulation pipe 20 passes through the generator 41 and forms a first cooling section 21 within the generator 41. The first cooling section 21 is a pipe section in which high-temperature drilling fluid flows. The cooling water pipe 30 passes through the absorber 42 and forms a first heating section 31 within the absorber 42. The first heating section 31 is a pipe section in which cooling water flows.

[0075] The first medium circulation pipeline 45 includes a dilute solution pipeline 451 and a concentrated solution pipeline 452, both connected between the generator 41 and the absorber 42.

[0076] The inlet of the dilute solution pipe 451 is connected to the bottom of the absorber 42, and its outlet is located inside the generator 41. The outlet of the dilute solution pipe 451 is positioned above the first cooling section 21 of the drilling fluid circulation pipe 20. The dilute lithium bromide solution in the absorber 42 flows through the dilute solution pipe 451 to the generator 41 and is sprayed onto the first cooling section 21. The dilute lithium bromide solution exchanges heat with the drilling fluid in the first cooling section 21, generating water vapor and simultaneously forming a concentrated lithium bromide solution. The drilling fluid in the drilling fluid circulation pipe 20 undergoes primary cooling after flowing through the first cooling section 21. The initial temperature of the drilling fluid is approximately 125 degrees Celsius, and after primary cooling, the temperature can be reduced to approximately 95 degrees Celsius.

[0077] The inlet of the concentrated solution pipe 452 is connected to the bottom of the generator 41, and its outlet is located inside the evaporator 44. The outlet of the concentrated solution pipe 452 is located above the first heating section 31 of the cooling water pipe 30. The concentrated lithium bromide solution in the generator 41 can flow to the absorber 42 through the concentrated solution pipe 452 and be sprayed onto the first heating section 31. The concentrated lithium bromide solution exchanges heat with the cooling water in the first heating section 31 to cool down and absorbs water vapor in the absorber 42 to form a dilute lithium bromide solution. The cooling water in the cooling water pipe 30 is initially heated by heat exchange. The temperature of the cooling water after the initial heat exchange is between 35 degrees Celsius and 38 degrees Celsius. The water vapor in the absorber 42 comes from the evaporator 44. This process will be described below.

[0078] Preferably, a sprayer is connected to the outlet of the dilute solution pipeline 451, and the first cooling section 21 of the drilling fluid circulation pipeline 20 is bent to form a serpentine or spiral section. The dilute lithium bromide solution can be fully sprayed onto the serpentine or spiral section by the sprayer, thereby improving the heat exchange effect between the dilute lithium bromide solution and the high-temperature drilling fluid in the first cooling section 21, and thus improving the conversion efficiency of the lithium bromide solution and the primary cooling effect of the drilling fluid.

[0079] Correspondingly, a sprayer is connected to the outlet of the concentrated solution pipeline 452, and the first heating section 31 of the cooling water pipeline 30 is bent to form a serpentine or spiral section. The concentrated lithium bromide solution can be fully sprayed onto the serpentine or spiral section by the sprayer, thereby improving the heat exchange effect between the concentrated lithium bromide solution and the cooling water in the first heating section 31, and thus improving the conversion effect of the lithium bromide solution.

[0080] Preferably, a second liquid pump 13 is provided on the dilute solution pipeline 451 or the concentrated solution pipeline 452, which can provide power for the flow of lithium bromide solution in the pipeline.

[0081] According to one embodiment of the present invention, such as Figure 1As shown, a third heat exchanger 453 is provided between the dilute solution pipeline 451 and the concentrated solution pipeline 452. The third heat exchanger 453 can realize heat exchange between the concentrated lithium bromide solution and the dilute lithium bromide solution, so as to improve the energy utilization efficiency of the entire system.

[0082] Furthermore, such as Figure 1 As shown, a first steam pipe 46 is connected between the top outlet of the generator 41 and the top inlet of the condenser 43. During the process of the dilute lithium bromide solution in the generator 41 being regenerated into a concentrated lithium bromide solution under the drive of high-temperature drilling fluid, heat is absorbed and water vapor is generated. The water vapor generated in the generator 41 can enter the condenser 43 through the first steam pipe 46.

[0083] After passing through the absorber 42, the cooling water pipe 30 passes through the condenser 43 and forms a second heating section 32 inside the condenser 43. The outlet of the first steam pipe 46 is located above the second heating section 32. The water vapor generated in the generator 41 enters the condenser 43 through the first steam pipe 46 and is sprayed onto the second heating section 32. The water vapor releases heat and liquefies into condensate. At the same time, the cooling water in the cooling water pipe 30 is heated again by heat exchange. The temperature of the cooling water after the second heat exchange is between 40 degrees Celsius and 45 degrees Celsius.

[0084] Preferably, the second heating section 32 of the cooling water pipe 30 is bent to form a serpentine or spiral pipe section, so that the water vapor flowing out of the outlet of the first steam pipe 46 can be fully sprayed on the serpentine or spiral pipe section, thereby improving the heat exchange effect between the water vapor and the cooling water in the second heating section 32, and thus improving the liquefaction effect of the water vapor.

[0085] Furthermore, such as Figure 1 As shown, the cooling water pipe 30 enters the first heat exchanger 60 after passing through the condenser 43, forming a third heating section 33 within the first heat exchanger 60; simultaneously, the drilling fluid circulation pipe 20 also enters the first heat exchanger 60 after passing through the generator 41, forming a second cooling section 22 within the first heat exchanger 60. Within the first heat exchanger 60, because the temperature of the drilling fluid after primary cooling (around 95 degrees Celsius) is still higher than the temperature of the cooling water after two heat exchange heating stages (between 40 and 45 degrees Celsius), a heat exchange process occurs between the drilling fluid and the cooling water. The drilling fluid in the drilling fluid circulation pipe 20 receives secondary cooling, while the cooling water in the cooling water pipe 30 receives another heat exchange heating stage. The drilling fluid, at approximately 95 degrees Celsius (after primary cooling), can be cooled to approximately 50 degrees Celsius after secondary cooling.

[0086] Furthermore, such as Figure 1As shown, a condensate pipe 48 is connected between the bottom outlet of the condenser 43 and the evaporator 44. Water vapor is liquefied into condensate in the condenser 43, and the condensate enters the evaporator 44 through the condensate pipe 48.

[0087] A heat exchange medium (also known as a refrigerant) circulates within the second medium circulation pipe 50. This heat exchange medium can be water or ethylene glycol. The high-temperature end of the second medium circulation pipe 50 extends into the evaporator 44 to form an evaporation heat exchange section 51. The outlet of the condensate pipe 48 extends into the evaporator 44 and is located directly above the evaporation heat exchange section 51. Water vapor generated in the condenser 43 enters the evaporator 44 through the condensate pipe 48 and is sprayed onto the evaporation heat exchange section 51 of the second medium circulation pipe 50. The condensate vaporizes into water vapor through heat exchange, and the high-temperature heat exchange medium in the second medium circulation pipe 50 is converted into a low-temperature heat exchange medium.

[0088] Preferably, a sprayer is connected to the outlet of the condensate pipe 48, and the evaporation heat exchange section 51 of the second medium circulation pipe 50 is bent to form a serpentine pipe section or a spiral pipe section. The condensate can be fully sprayed onto the serpentine pipe section or spiral pipe section by the sprayer, thereby improving the heat exchange effect between the condensate and the high-temperature heat exchange medium in the evaporation heat exchange section 51.

[0089] Furthermore, such as Figure 1 As shown, a second steam pipe 47 is connected between the top outlet of the evaporator 44 and the top inlet of the absorber 42. The water vapor generated in the evaporator 44 enters the absorber 42 through the second steam pipe 47 and is absorbed by the concentrated lithium bromide solution in the absorber 42 to form a dilute lithium bromide solution.

[0090] After passing through the first heat exchanger 60, the drilling fluid circulation pipe 20 enters the second heat exchanger 61 to form the third cooling section 23. The low-temperature end of the second medium circulation pipe 50 is also located in the second heat exchanger 61. Within the second heat exchanger 61, the temperature of the heat exchange medium at the low-temperature end is lower than the temperature of the drilling fluid in the third cooling section 23. Therefore, heat exchange can occur between the heat exchange medium and the drilling fluid. The drilling fluid in the drilling fluid circulation pipe 20 releases heat and cools down, achieving three-stage cooling, while the heat exchange medium in the second medium circulation pipe 50 absorbs heat and heats up, generating a high-temperature heat exchange medium. The drilling fluid, with a temperature of approximately 50 degrees Celsius (after two-stage cooling), can be cooled to approximately 25 degrees Celsius after three-stage cooling.

[0091] Preferably, a liquid pump (not shown in the figure) is provided on the second medium circulation pipe 50, which can drive the heat exchange medium to circulate between the second heat exchanger 61 and the evaporator 44.

[0092] According to one embodiment of the invention, such as Figure 1As shown, the second heat exchanger 61 includes a drilling fluid storage tank 611 disposed on the drilling fluid circulation pipeline 20, a heat exchange medium storage tank 612 disposed on the second medium circulation pipeline 50, and a heat pipe 613 connecting the drilling fluid storage tank 611 and the heat exchange medium storage tank 612; the drilling fluid storage tank 611 forms the third cooling section 23 on the drilling fluid circulation pipeline 20, the heat exchange medium storage tank 612 forms the low temperature end of the second medium circulation pipeline 50, and the end of the second medium circulation pipeline 50 away from the heat exchange medium storage tank 612 passes through the evaporator 44 to form the high temperature end.

[0093] Specifically, in this embodiment, a combined heat exchange structure consisting of a drilling fluid storage tank 611, a heat exchange medium storage tank 612, and heat pipes 613 is used to replace the original second heat exchanger 61 structure that directly exchanges heat. Since the drilling fluid storage tank 611 and the heat exchange medium storage tank 612 can respectively hold a large amount of drilling fluid and heat exchange medium, and a large number of heat pipes 613 can be connected between the drilling fluid storage tank 611 and the heat exchange medium storage tank 612 for heat transfer, the heat exchange effect between the drilling fluid and the heat exchange medium can be improved.

[0094] According to one embodiment of the present invention, a water supply pipe is connected to the cooling water pipe 30 between the condenser 43 and the first heat exchanger 60, and the water supply pipe can supply cooling water to the cooling water pipe 30.

[0095] Cooling water is added to the cooling water pipe 30 through the water supply pipe, which increases the flow rate of cooling water entering the first heat exchanger 60. The temperature of the drilling fluid flowing out of the first heat exchanger 60 is lower (the temperature is even lower after the second heat exchange). When the drilling fluid enters the second heat exchanger 61 for tertiary cooling, the required heat exchange is relatively small, thereby achieving a surplus of heat exchange medium (coolant) in the second heat exchanger 61.

[0096] According to one embodiment of the present invention, a drain pipe is connected to the cooling water pipe 30 between the condenser 43 and the first heat exchanger 60, and the drain pipe can lead out the cooling water in the cooling water pipe 30.

[0097] A portion of the cooling water in the cooling water pipe 30 is drawn out through the drain pipe, thereby reducing the flow rate of the cooling water entering the first heat exchanger 60. This results in a higher temperature of the cooling water after heat exchange with the drilling fluid in the first heat exchanger 60, reaching over 50 degrees Celsius. Cooling water at this temperature can be supplied to users for heating or domestic water use.

[0098] According to one embodiment of the present invention, such as Figure 1As shown, the drilling fluid circulation cooling system also includes a sedimentation tank 11 installed on the drilling fluid circulation pipeline 20. The sedimentation tank 11 is located upstream of the first cooling section 21, along the flow direction of the drilling fluid. The sedimentation tank 11 can first separate and settle the drilling fluid, preventing solid impurities from circulating with the drilling fluid in the drilling fluid circulation pipeline 20, which could lead to pipeline damage or blockage. Furthermore, solid impurities carried in the drilling fluid can increase the power and energy consumption required for drilling fluid circulation.

[0099] Implementation Method Two:

[0100] The present invention also provides a drilling fluid circulation cooling method, wherein the method is implemented using a drilling fluid circulation cooling system as described in Embodiment 1, and the drilling fluid circulation cooling method includes the following steps:

[0101] S1: The drilling fluid in the wellbore 10 is transported to the generator 41 in the absorption heat pump 40 for primary cooling. The drilling fluid exchanges heat with the first medium in the generator 41 to cool down.

[0102] S2: The drilling fluid after primary cooling is transported to the first heat exchanger 60 for secondary cooling, where the drilling fluid exchanges heat with cooling water to cool down.

[0103] S3: The drilling fluid after secondary cooling is transported to the second heat exchanger 61 for tertiary cooling. The drilling fluid exchanges heat with the heat exchange medium in the second heat exchanger 61 to reduce its temperature.

[0104] In this process, the cooling water is heated by heat exchange in the absorber 42 and cooler of the absorption heat pump 40 before being introduced into the first heat exchanger 60. The heat exchange medium is cooled by heat exchange in the evaporator 44 of the absorption heat pump 40 before being introduced into the second heat exchanger 61.

[0105] The drilling fluid circulation cooling method of this invention adopts a three-stage cooling approach. The drilling fluid flows through a generator 41 (where it undergoes primary cooling) to drive an absorption heat pump 40. Subsequently, the drilling fluid exchanges heat with cooling water through a first heat exchanger 60 (secondary cooling), and finally exchanges heat with a refrigerant through a second heat exchanger 61 (tertiary cooling) before being reinjected into the well as needed. Using residual heat from the drilling fluid to drive the absorption heat pump 40 results in low power consumption; it enables large temperature difference heat exchange of the drilling fluid, unaffected by ambient temperature, achieving a temperature difference of approximately 100 degrees Celsius before and after cooling, with the final temperature of the cooled drilling fluid remaining stable at around 25 degrees Celsius; the closed-loop heat exchange process minimizes environmental impact on cooling performance, resulting in excellent energy-saving and emission-reduction effects.

[0106] In step S1, the drilling fluid enters the generator 41 inside the absorption heat pump 40 through the drilling fluid circulation pipe 20, and undergoes a heat exchange process with the dilute lithium bromide solution in the generator 41. The dilute lithium bromide solution is regenerated into a concentrated lithium bromide solution and water vapor is generated. The temperature of the drilling fluid can be reduced from 125 degrees Celsius to 95 degrees Celsius. The lithium bromide solution can achieve the conversion between dilute and concentrated solutions between the generator 41 and the absorber 42, while simultaneously transferring heat.

[0107] In step S2, the drilling fluid after primary cooling is transported to the first heat exchanger 60. The first heat exchanger 60 is equipped with a cooling water pipe 30. The cooling water in the cooling water pipe 30 exchanges heat and heats up in the absorber 42 and cooler in the absorption heat pump 40 before entering the first heat exchanger 60. The drilling fluid exchanges heat and cools down with the cooling water in the cooling water pipe 30 in the first heat exchanger 60. The temperature of the drilling fluid can be reduced from 95 degrees Celsius to 50 degrees Celsius.

[0108] In step S3, the drilling fluid after secondary cooling is transported to the second heat exchanger 61. The second heat exchanger 61 is provided with a second medium circulation pipe 50, in which heat exchange medium (coolant) circulates. The drilling fluid exchanges heat with the heat exchange medium in the second heat exchanger 61 and cools down. The temperature of the drilling fluid can be reduced from 50 degrees Celsius to 25 degrees Celsius.

[0109] According to one embodiment of the present invention, prior to the step of conveying the drilling fluid in the wellbore 10 to the generator 41 within the absorption heat pump 40 for primary cooling, the following step is further included:

[0110] S0: The drilling fluid in the wellbore 10 is transported to the sedimentation tank 11 for sedimentation.

[0111] In step S0, the drilling fluid is pre-sedimented and separated in the sedimentation tank 11 to prevent solid impurities from circulating in the drilling fluid circulation pipe 20 with the drilling fluid, which could lead to pipe damage or blockage.

[0112] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drilling fluid circulation cooling system, characterized in that, include: A drilling fluid circulation pipeline is connected to the wellbore, allowing drilling fluid in the wellbore to enter the drilling fluid circulation pipeline and flow back into the wellbore; An absorption heat pump includes a generator, an absorber, a condenser, and an evaporator. A first medium circulation pipe is connected between the generator and the absorber. A first steam pipe is connected between the generator and the condenser. A condensate pipe is connected between the condenser and the evaporator. A second steam pipe is connected between the evaporator and the absorber. A cooling water pipe passes through the absorber and the condenser in sequence along the water flow direction, and a first heat exchanger is provided at the outlet end of the cooling water pipe; A second medium circulation pipe is connected to a second heat exchanger, and at least a portion of the second medium circulation pipe is located inside the evaporator; The drilling fluid circulation pipeline has a first cooling section, a second cooling section, and a third cooling section respectively located in the generator, the first heat exchanger, and the second heat exchanger.

2. The drilling fluid circulating cooling system according to claim 1, characterized in that, The location on the second medium circulation pipe that is connected to or near the second heat exchanger is the high-temperature end of the second medium circulation pipe, and the portion of the second medium circulation pipe located inside the evaporator is the low-temperature end of the second medium circulation pipe.

3. The drilling fluid circulation cooling system according to claim 2, characterized in that, The first medium circulating in the first medium circulation pipe is a lithium bromide solution or ammonia water.

4. The drilling fluid circulating cooling system according to claim 3, characterized in that, The first medium circulation pipeline includes a dilute solution pipeline and a concentrated solution pipeline, both connected between the generator and the absorber, and the cooling water pipeline has a first heating section located inside the absorber; The dilute lithium bromide solution in the dilute solution pipeline flows to the generator and is sprayed onto the first cooling section. The dilute lithium bromide solution heats up and generates water vapor, while simultaneously forming a concentrated lithium bromide solution. The concentrated lithium bromide solution in the concentrated solution pipeline flows to the absorber and is sprayed onto the first heating section. The concentrated lithium bromide solution exchanges heat, cools down, and absorbs water vapor, while simultaneously forming a concentrated lithium bromide solution.

5. The drilling fluid circulating cooling system according to claim 4, characterized in that, A third heat exchanger is provided between the dilute solution pipeline and the concentrated solution pipeline.

6. The drilling fluid circulating cooling system according to claim 4, characterized in that, The cooling water pipe also has a second heating section located inside the condenser. The water vapor generated in the generator enters the condenser through the first steam pipe and is sprayed onto the second heating section, where the water vapor undergoes heat exchange and liquefies into condensate.

7. The drilling fluid circulating cooling system according to claim 6, characterized in that, The water vapor generated in the condenser enters the evaporator through the condensate pipe and is sprayed onto the high-temperature end of the second medium circulation pipe, where the condensate is vaporized into water vapor through heat exchange. The water vapor generated in the evaporator enters the absorber through the second steam pipe and is absorbed by the dilute lithium bromide solution to form the concentrated lithium bromide solution.

8. The drilling fluid circulating cooling system according to claim 5, characterized in that, The cooling water pipe also has a third heating section located in the first heat exchanger, which can exchange heat with the second cooling section.

9. The drilling fluid circulating cooling system according to claim 2, characterized in that, The second heat exchanger includes a drilling fluid storage tank disposed on the drilling fluid circulation pipeline, a heat exchange medium storage tank disposed on the second medium circulation pipeline, and a heat pipe connecting the drilling fluid storage tank and the heat exchange medium storage tank. The drilling fluid storage tank forms the third cooling section on the drilling fluid circulation pipeline.

10. The drilling fluid circulating cooling system according to claim 9, characterized in that, The heat exchange medium storage tank forms the low-temperature end, and the end of the second medium circulation pipe away from the heat exchange medium storage tank passes through the evaporator to form the high-temperature end.

11. The drilling fluid circulating cooling system according to claim 1, characterized in that, A water supply pipe is connected to the cooling water pipe between the condenser and the first heat exchanger, and the water supply pipe can supply cooling water to the cooling water pipe.

12. The drilling fluid circulating cooling system according to claim 1, characterized in that, A drain pipe is connected to the cooling water pipe between the condenser and the first heat exchanger, and the drain pipe can lead out the cooling water in the cooling water pipe.

13. The drilling fluid circulating cooling system according to claim 1, characterized in that, The drilling fluid circulation cooling system also includes a sedimentation tank installed on the drilling fluid circulation pipeline, and the sedimentation tank is located upstream of the first cooling section along the flow direction of the drilling fluid.

14. The drilling fluid circulating cooling system according to claim 1, characterized in that, The drilling fluid circulation pipeline, the first medium circulation pipeline, and the second medium circulation pipeline are all equipped with liquid pumps that drive the flow of fluid.

15. A drilling fluid circulation cooling method, characterized in that, The method is implemented using a drilling fluid circulation cooling system as described in any one of claims 1-14, wherein the drilling fluid circulation cooling method comprises: The drilling fluid in the wellbore is transported to a generator in an absorption heat pump for primary cooling, where the drilling fluid exchanges heat with a first medium to lower its temperature. The drilling fluid after primary cooling is transported to the first heat exchanger for secondary cooling, where the drilling fluid exchanges heat with cooling water to lower its temperature. The drilling fluid after secondary cooling is transported to the second heat exchanger for tertiary cooling, where the drilling fluid exchanges heat with the heat exchange medium to cool down. The cooling water is heated by heat exchange in the absorber and cooler of the absorption heat pump before being introduced into the first heat exchanger, and the heat exchange medium is cooled by heat exchange in the evaporator of the absorption heat pump before being introduced into the second heat exchanger.

16. The drilling fluid circulation cooling method according to claim 15, characterized in that, Before the step of delivering drilling fluid from the wellbore to the generator within the absorption heat pump for primary cooling, the process also includes: The drilling fluid in the wellbore is transported to a settling tank for sedimentation.

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