Drilling fluid mud cooler, underwater cooler module, and underwater drilling fluid mud cooling system

Abstract

The application discloses a drilling fluid mud cooler, an underwater cooler module and an underwater drilling fluid mud cooling system. The drilling fluid mud cooler comprises a sealed shell, a tube bundle structure arranged in a containing space, the tube bundle structure comprises coaxially arranged inner cooling pipes and outer cooling pipes, a first fluid passage is formed in the inner cooling pipes, a second fluid passage for flowing of fresh water is formed between the inner cooling pipes and the outer cooling pipes; an external cooling loop for flowing of an external cooling medium is further arranged on the outer side of the tube bundle structure, and the second fluid passage is arranged between the first fluid passage and the external cooling loop. The underwater drilling fluid mud cooling system can be used in a shallow water environment and can also be applied to a deep water environment. The drilling fluid mud cooler is arranged and operated in a seawater environment, and low-temperature seawater at a specific depth is used to efficiently cool the drilling fluid. The problem that the high-temperature drilling fluid causes an increase in the equipment failure rate due to insufficient cooling when returning to a bottom-supported drilling platform is solved.

Description

Technical Field

[0001] This invention relates to the field of high-temperature oil and gas well drilling technology, and in particular to a drilling fluid mud cooler, a subsea cooler module, and a subsea drilling fluid mud cooling system. Background Technology

[0002] In high-temperature oil and gas well drilling operations, the high temperature of the formation sediments downhole causes the circulating drilling fluid temperature to rise sharply, reaching 80 to 150 degrees Celsius or higher when returned to the jack-up drilling platform. This type of high-temperature drilling fluid poses multiple challenges to the surface circulation system: the rheological properties of the drilling fluid change uncontrollably with increasing temperature, leading to abnormal viscosity fluctuations, decreased gel strength, and reduced cuttings carrying capacity, which in turn causes problems such as increased cuttings settling and reduced wellbore cleaning efficiency; simultaneously, the high-temperature environment accelerates the aging and failure of rubber components in pumps, valves, seals, and solids control equipment, significantly increasing equipment failure rates and maintenance costs. While conventionally used plate heat exchangers have the advantage of compact structure, in areas with high ambient seawater temperatures (such as the surface water temperature in the South Asian seas reaching 28 to 30 degrees Celsius in summer), the reduced temperature difference between the high-temperature drilling fluid and the cooling medium significantly reduces heat flux and approach temperature, preventing the drilling fluid outlet temperature from falling below the equipment's safe operating threshold. Furthermore, the seawater side of plate heat exchangers is susceptible to biofouling, with a dense biofilm forming on the flow channel surface, leading to decreased heat transfer efficiency, increased pressure drop, and accelerated corrosion. Under high-temperature conditions, frequent mechanical failures such as gasket failure and leakage, and plate warping further weaken cooling performance. These shortcomings make existing surface cooling technologies insufficient to meet the demands of high-temperature drilling operations, especially lacking adaptable solutions in shallow and deep water environments. There is an urgent need to develop new cooling devices to address the challenges of drilling fluid temperature control under complex conditions. Existing technologies urgently require improvement to address these issues. Summary of the Invention

[0003] To address the shortcomings of the existing technologies, this invention provides a drilling fluid mud cooler, a subsea cooler module, and a subsea drilling fluid mud cooling system to solve the problems of increased equipment failure rate and high maintenance costs caused by insufficient cooling of high-temperature drilling fluid when returning to the bottom-mounted drilling platform.

[0004] This invention is achieved using the following technical solution: A drilling fluid mud cooler, comprising: A sealed shell, whose interior defines the space for containment; The tube bundle structure disposed within the accommodating space includes an inner cooling tube and an outer cooling tube coaxially sleeved together. A first fluid channel for drilling fluid to flow is formed inside the inner cooling tube, and a second fluid channel for fresh water to flow is formed between the inner cooling tube and the outer cooling tube. The drilling fluid inlet and outlet are provided on the shell and communicate with the first fluid channel, and the fresh water inlet and outlet are communicated with the second fluid channel. The fluid in the first fluid channel and the fluid in the second fluid channel are arranged to flow in opposite directions within the tube bundle structure. The outer side of the tube bundle structure is provided with an external cooling circuit for the flow of external cooling medium. The second fluid channel is sandwiched between the first fluid channel and the external cooling circuit, and is used to provide a safe sealing barrier for the inner tube bundle under external high pressure environment.

[0005] Furthermore, the containing space is divided into a high-temperature drilling fluid inlet chamber, a cooled drilling fluid outlet chamber, a fresh water inlet chamber, and a fresh water outlet chamber. The high-temperature drilling fluid inlet chamber and the cooled drilling fluid outlet chamber are respectively connected to the high-temperature drilling fluid inlet and the cooled drilling fluid outlet. The fresh water inlet chamber and the fresh water outlet chamber are respectively connected to the fresh water inlet and the fresh water outlet. The two ends of the second fluid channel are respectively connected to the fresh water inlet chamber and the fresh water outlet chamber to realize the distribution and convergence of fresh water. The two ends of all the internal cooling pipes of the tube bundle structure are respectively connected to the high-temperature drilling fluid inlet chamber and the cooled drilling fluid outlet chamber to evenly distribute the high-temperature drilling fluid to each internal cooling pipe and converge and discharge the cooled drilling fluid.

[0006] Furthermore, multiple baffles are arranged at intervals along the axis perpendicular to the tube bundle in the external cooling circuit, and the flow direction of the external cooling medium is opposite to the flow direction of the drilling fluid in the tube bundle.

[0007] A submersible cooler module includes the aforementioned drilling fluid mud cooler and a freshwater circulation system. The freshwater circulation system includes a freshwater cooling water unit connected to a freshwater outlet and a freshwater inlet, a freshwater loop expansion tank connected to the freshwater cooling water unit, and an environmental pressure compensator connected to the freshwater loop expansion tank. The environmental pressure compensator is connected to the environmental seawater pressure. The freshwater cooling water unit is connected to a freshwater cooling pump, which delivers freshwater to the freshwater inlet chamber through the freshwater inlet.

[0008] Furthermore, it also includes a seawater cooling system, which includes a seawater cooling pump and a seawater suction filter connected to the seawater cooling pump. The drilling fluid mud cooler also includes a seawater cooling chamber that forms an external cooling circuit. The seawater cooling chamber is provided with a seawater inlet connected to the seawater cooling pump and a seawater outlet connected to a warm seawater discharge pipeline. The seawater cooling chamber is provided with an oil leak sensor and an oil leak connector.

[0009] A subsea drilling fluid mud cooling system includes the aforementioned subsea cooler module, and further includes a platform-side drilling fluid circulation unit, a power control umbilical cable, and a drilling fluid delivery assembly; the drilling fluid delivery assembly is configured to be selectively assembled between a first configuration and a second configuration. The first configuration includes at least two flexible hoses to connect the platform-side circulation unit to the drilling fluid inlet and outlet of the subsea drilling fluid mud cooler; The second form includes a drilling fluid cooler piping unit, which integrates at least two rigid pipes to establish a rigid connection between the platform-side circulation unit and the drilling fluid inlet and outlet of the subsea drilling fluid mud cooler. The power control umbilical cable remains connected to the platform-side drilling fluid circulation unit and the subsea drilling fluid mud cooler in both configurations. The platform-side drilling fluid circulation unit is compatible with both the first and second configurations on the same supply / return flow path. It is arranged on the bottom-mounted drilling platform and is configured to output high-temperature drilling fluid underwater and recover cooled drilling fluid.

[0010] Furthermore, the submersible cooler module is equipped with a shallow water mode interface, which includes a high-temperature drilling fluid inlet connector and a cooled drilling fluid outlet connector for connecting the high-temperature drilling fluid supply hose and the cooled drilling fluid return hose, respectively, and a wire rope interface for connecting the laying winch wire rope. The bottom-mounted drilling platform is equipped with a drilling fluid supply hose winch and a drilling fluid return hose winch for connecting the high-temperature drilling fluid supply hose and the cooled drilling fluid return hose, respectively, and a lowering and recovery unit for connecting the laying winch wire rope.

[0011] Furthermore, the subsea cooler module is equipped with a deep-water mode interface, which includes a modular interface connector with a flexible joint. The modular interface connector integrates a high-temperature drilling fluid supply pipeline and a cooled drilling fluid return pipeline. The bottom-mounted drilling platform is equipped with a pipeline unit load suspension module and a mud pad module with a guide cable for connecting the subsea cooler module and the pipeline unit load suspension module.

[0012] Furthermore, the high-temperature drilling fluid supply pipeline and the cooled drilling fluid return pipeline are arranged eccentrically and non-coaxially within the drilling fluid cooler pipeline unit, and are tightly secured to the outside of the high-temperature drilling fluid supply pipeline and the cooled drilling fluid return pipeline by the cooler pipeline clamping unit, in order to maintain the relative position and parallelism of the two pipelines.

[0013] Furthermore, the drilling fluid cooler piping unit includes a lower cooler pipe connector and an upper cooler pipe connector. The high-temperature drilling fluid supply pipe and the cooled drilling fluid return pipe are connected to the lower cooler pipe connector and the upper cooler pipe connector. The lower cooler pipe connector includes a flange and a bolt assembly fastened to the flange. The lower cooler pipe connector is detachably rigidly connected to the modular interface connector through the bolt assembly. The upper cooler pipe connector is suspended by a tensioning unit. The upper cooler pipe connector includes a high-temperature drilling fluid sealing short section and a cooled drilling fluid sealing short section spaced apart. The high-temperature drilling fluid sealing short section is coaxially sealed with the high-temperature drilling fluid supply pipe, and the cooled drilling fluid sealing short section is coaxially sealed with the cooled drilling fluid return pipe.

[0014] Furthermore, the platform-side drilling fluid circulation unit includes: Drilling fluid cooling and buffer tanks; A high-temperature drilling fluid supply booster pump is connected to the drilling fluid cooling and buffer tank. The inlet of the high-temperature drilling fluid supply booster pump is connected to a high-temperature drilling fluid shut-off valve, which is used to deliver the high-temperature drilling fluid downward to the underwater drilling fluid mud cooler in the submerged state. The high-temperature drilling fluid inlet valve and hot drilling fluid inlet connector, which are connected to the drilling fluid cooling and buffer tank, are used to introduce and pressurize the hot drilling fluid in the water surface drilling fluid purification chamber. A cooled drilling fluid return line equipped with a drilling fluid flow meter is connected to the drilling fluid cooling and buffer tank for precise control of the cooled drilling fluid flow rate. In addition, there are cooling drilling fluid return inlet valves and working drilling fluid system connectors, which allow the cooled drilling fluid to flow smoothly into the working drilling fluid tank system.

[0015] Furthermore, the platform-side drilling fluid circulation unit also includes a drilling water flushing pipeline joint and a drilling water flushing valve. When the high-temperature drilling fluid inlet valve is closed, the drilling water can flow into the drilling fluid cooling and buffer tank through the drilling water flushing valve.

[0016] Furthermore, the platform-side drilling fluid circulation unit also includes a flushing bypass valve, a vent valve, a discharge delivery pump, a discharge valve, and a discharge pipeline connector, used to discharge the displacement water in the cooling circuit when the cooling drilling fluid return inlet valve is closed.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least the following: (1) The drilling fluid mud cooler provided by this invention is deployed deep underwater, effectively utilizing the low-temperature deep-sea seawater as an external cooling medium. The low-temperature deep-sea seawater provides a greater temperature difference, thereby improving cooling efficiency and avoiding the problem of insufficient cooling capacity due to the high temperature of surface seawater in summer. Secondly, a three-layer fluid channel design is adopted, namely drilling fluid, fresh water, and external cooling medium. This design not only realizes heat exchange, but more importantly, the fresh water in the second fluid channel provides a safe sealing barrier for the inner tube bundle under external high pressure. Through the fresh water barrier mechanism, even if the inner cooling pipe leaks, the drilling fluid will first enter the fresh water channel instead of being directly discharged into the ocean, enhancing the safety and environmental friendliness of the system operation.

[0018] Furthermore, the fluids in the first and second fluid channels flow in opposite directions, further optimizing heat exchange efficiency. This counter-flow design ensures that the temperature difference between the two fluids remains high throughout the heat exchange process, allowing the drilling fluid to be cooled to a lower temperature. This achieves better cooling performance with the same heat exchange area compared to some simple co-flow or cross-flow heat exchangers.

[0019] (2) The underwater cooler module provided by this invention achieves a dual heat exchange mechanism by using fresh water as an intermediate cooling medium. The heat of the drilling fluid is first transferred to the fresh water, and then from the fresh water to the low-temperature seawater in the external cooling circuit, avoiding direct contact between the drilling fluid and the high-temperature surface seawater. Since the environmental pressure compensator automatically matches the external seawater pressure, the sealing integrity of the fresh water circuit in the high-pressure underwater environment is ensured, effectively preventing fresh water leakage or deformation of the tube bundle structure caused by pressure imbalance. Furthermore, the fresh water cooling water unit can independently control the fresh water temperature, so that it is not affected by the seasonal temperature fluctuations of the surface seawater, thereby maintaining a stable cooling efficiency.

[0020] (3) The subsea drilling fluid mud cooling system provided by this invention achieves effective cooling of drilling fluid under different water depth conditions. In shallow water mode, the flexible hose adapts to the installation environment on the seabed surface, facilitating rapid deployment and retrieval; in deep water mode, the rigid pipeline resists the high pressure of the deep sea, ensuring structural stability. Both modes share the same platform-side drilling fluid circulation unit, simplifying system design and reducing operational complexity. This not only improves cooling efficiency, ensuring the drilling fluid temperature stabilizes below the equipment design limit, but also reduces problems such as pump and valve seal failure and rheological runaway caused by insufficient cooling, significantly reducing maintenance costs and unplanned downtime. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the arrangement of the underwater drilling fluid mud cooling system in a shallow water environment according to an embodiment of the present invention; Figure 2This is a schematic diagram of the arrangement of the underwater drilling fluid mud cooling system in a deep-water environment according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the drilling fluid circulation unit on the platform side of the subsea drilling fluid mud cooling system of the present invention, used in shallow water operations on a bottom-mounted drilling platform. Figure 4 This is a schematic diagram of the drilling fluid circulation unit on the platform side of the subsea drilling fluid mud cooling system of the present invention, used in deep-water operations on a bottom-mounted drilling platform. Figure 5 This is a schematic diagram of a drilling fluid mud cooler according to an embodiment of the present invention; Figure 6 This is a schematic diagram of an underwater cooler module according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the underwater layout of the underwater drilling fluid mud cooling system in a shallow water environment according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the underwater layout of the underwater drilling fluid mud cooling system in a deep-water environment according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the interface structure of the underwater cooler module of the drilling fluid mud cooler in a shallow water environment according to an embodiment of the present invention. Figure 10 This is a schematic diagram of the interface structure of the underwater cooler module of the drilling fluid mud cooler in a deep-water environment according to an embodiment of the present invention; Figure 11 This is a schematic diagram of a single connector of the drilling fluid cooler piping unit suspended within the load suspension module of the piping unit according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the drilling fluid cooler piping unit according to an embodiment of the present invention; Figure 13 This is a schematic diagram of a pipe section of the drilling fluid cooler piping unit according to an embodiment of the present invention; Figure 14 This is a schematic diagram of the lower connector of the cooler pipe in an embodiment of the present invention; Figure 15 This is a schematic diagram of the arrangement of the drilling fluid supply / return hose winch according to an embodiment of the present invention; Figure 16 This is a schematic diagram of the recycling unit in an embodiment of the present invention; In the diagram: 1. Bottom-mounted drilling platform; 2. Sea surface; 3. Seabed; 4. Derrick; 5. Drilling guide pipe; 6. Drilling fluid purification chamber; 7. Deck crane; 8. Drilling fluid supply hose winch; 9. Drilling fluid return hose winch; 10. Lowering and recovery unit; 11. High-temperature drilling fluid supply hose; 12. Cooled drilling fluid return hose; 13. Deploying winch wire rope; 14. Power control umbilical cable; 15. Subsea cooler module; 16. Piping unit load suspension module; 17. Power and control umbilical cable winch; 18. Drilling fluid cooler piping unit; 19. Guide cable; 20. Mud pad module; 21. Power and control unit; 22. Hot drilling fluid inlet connector; 23. Drilling fluid cooling and buffer tank; 24. Drilling fluid working tank conveyor. 25. Pump; 26. Cooled drilling fluid return line; 27. Drilling fluid flow meter; 28. High-temperature drilling fluid supply booster pump; 29. ​​High-temperature drilling fluid supply line; 30. Cooling circuit pressure test connector; 31. High-temperature drilling fluid inlet valve; 32. Drilling water flushing line connector; 33. Drilling water flushing valve; 34. Cooled drilling fluid return inlet valve; 35. High-temperature drilling fluid shut-off valve; 36. Cooling circuit test shut-off valve; 37. Delivery valve; 38. Flushing bypass valve; 39. Drilling working drilling fluid system connector; 40. Drain valve; 41. Discharge line connector; 42. High-temperature drilling fluid supply line; 43. Cooled drilling fluid return line; 44. Cooled drilling fluid outlet; 45. High-temperature drilling fluid inlet; 46. Seawater inlet; 47. Seawater outlet; 48. Freshwater inlet; 49. Freshwater outlet; 50. Drilling fluid mud cooler; 51. High-temperature drilling fluid inlet chamber; 52. Cooled drilling fluid outlet chamber; 53. Freshwater inlet chamber; 54. Freshwater outlet chamber; 55. Seawater cooling chamber; 56. External cooling pipe; 57. Internal cooling pipe; 58. Drilling fluid mud pump; 59. Seawater cooling pump; 60. Freshwater cooling pump; 61. Seawater suction filter; 62. Warm seawater outlet; 63. Warm seawater discharge pipeline; 64. Freshwater inlet; 65. Freshwater cooling water unit; 66. Leakage sensor; 67. Freshwater circuit expansion tank; 68. Environmental pressure compensator; 69. Environmental seawater pressure; 70. Oil leak sensor; 71. High-temperature drilling fluid pump inlet; 72. Flexible connection 72. Modular interface connector; 73. Tensioning unit; 74. Drilling fluid diverter head; 75. Guide cable winch; 76. Hoses clamp; 77. Submersible jumper hose for cooled drilling fluid; 78. Submersible jumper hose for high-temperature drilling fluid; 79. Crane lifting lug flange; 80. Upper connector for cooler pipes; 81. Lower connector for cooler pipes; 82. Compensator accumulator; 83. Tensioning cylinder; 84. Cooler pipe clamping unit; 85. High-temperature drilling fluid sealing sub; 86. Submersible sealing sub; 87. Bolt assembly; 88. Hoses reel; 89. Hoses reel; 90. Hoses winch power unit; 91. Oil receiving tray device; 92. Hoses bending limit device; 93. Lowering and retrieval device cylinder; 94. Cable pulley;95. Umbilical cable pulley. Detailed Implementation

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0023] The terms used to express position and direction in this invention are illustrated with the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this invention.

[0024] In traditional high-temperature oil and gas well drilling operations, the high temperature of the formation sediments downhole leads to an increase in drilling fluid temperature. When the drilling fluid circulates back to the jack-up drilling platform, the high temperature increases the failure rate of pumps, valves, coolers, and sealing components. This problem stems from the high stress load that high temperatures place on seals, gaskets, and bearings. Simultaneously, the rheological properties of the drilling fluid change, including decreased viscosity, accelerated polymer degradation, and changes in surface tension. This results in decreased solids removal efficiency, increased cuttings settling, and poorer wellbore cleaning, ultimately complicating well pressure management. Specifically, the increased drilling fluid temperature reduces the efficiency of vibrating screens and mud cleaners, causing more solid particles to enter the in-use mud system, thus reducing solids control efficiency. Furthermore, changes in drilling fluid viscosity reduce annular friction and alter the calculated equivalent circulating density. The thermal gelling effect of some additives can also lead to unpredictable viscosity increases, thus posing challenges to well pressure management.

[0025] For example, during deep-water drilling operations in the high-temperature waters of South Asia during the summer, the ambient air temperature is high, and the surface seawater temperature is also high. Due to the reduced temperature difference between the high-temperature drilling fluid and the warm seawater, the heat flux of the plate heat exchanger decreases, preventing the drilling fluid outlet temperature from dropping below the equipment's design limit. In this scenario, the seawater side of the plate cooler is susceptible to biofouling, with biofilm forming on the flow channels and plate surfaces, leading to decreased heat transfer efficiency and increased pressure drop. Simultaneously, under high-temperature conditions, gasket failure and leakage, plate corrosion and erosion occur frequently. Thermal expansion and plate warping further exacerbate sealing failures, preventing effective cooling of the drilling fluid and keeping the pump and downstream equipment continuously at high temperatures.

[0026] If the above problems are not addressed, when the jack-up drilling platform 1 equipped with derrick 4 drills oil and gas wells in deep underground formations, the formation temperature will heat the drilling fluid in the drilling guide 5. When the drilling fluid is returned to the jack-up drilling platform 1, the temperature may be too high, and insufficient cooling of the drilling fluid will shorten the service life of the pumps and top drives, causing unpredictable changes in working performance. Specifically, the decrease in solids control efficiency will cause more solid particles to enter the mud system, causing the drilling fluid treatment and pumping system in the drilling fluid purification chamber 6 or other drilling fluid pumps in the drilling fluid working system to malfunction, resulting in more downhole drilling control problems. Furthermore, unplanned downtime events will occur frequently, not only increasing maintenance costs but also leading to a loss of actual effective drilling time, seriously affecting the continuity and economy of drilling operations. Therefore, the adverse effects of high-temperature drilling fluid on surface equipment will persist for a long time, restricting the reliability of high-temperature well drilling operations.

[0027] In this regard, this application proposes a drilling fluid mud cooler 49, comprising: A sealed shell, whose interior defines the space for containment; The tube bundle structure disposed within the accommodating space includes an inner cooling tube 56 and an outer cooling tube 55 coaxially sleeved. The inner cooling tube 56 forms a first fluid channel for drilling fluid to flow through, and the inner cooling tube 56 and the outer cooling tube 55 form a second fluid channel for fresh water to flow through. The drilling fluid inlet and outlet are provided on the shell and communicate with the first fluid channel, and the fresh water inlet and outlet are communicated with the second fluid channel. The fluid in the first fluid channel and the fluid in the second fluid channel are arranged to flow in opposite directions within the tube bundle structure. The outer side of the tube bundle structure is provided with an external cooling circuit for the flow of external cooling medium. The second fluid channel is sandwiched between the first fluid channel and the external cooling circuit, and is used to provide a safe sealing barrier for the inner tube bundle under external high pressure environment.

[0028] In this embodiment, the drilling fluid mud cooler 49 is a device used to reduce the temperature of high-temperature drilling fluid. During oil and gas drilling, the drilling fluid returning from downhole is usually at a high temperature. This cooler uses the principle of heat exchange to transfer the heat of the drilling fluid to the cooling medium, thereby cooling the drilling fluid to protect surface equipment and maintain the performance of the drilling fluid. The inner cooling pipe 56 is the innermost pipe in the tube bundle structure, forming a first fluid channel inside, specifically for the flow of high-temperature drilling fluid. The drilling fluid exchanges heat with the external cooling medium through this first fluid channel. The outer cooling pipe 55 is a pipe coaxially sleeved outside the inner cooling pipe 56, forming a second fluid channel between it and the inner cooling pipe 56 for the flow of fresh water. This fresh water channel acts as an intermediate cooling medium and a safety barrier during the cooling process. The second fluid channel is an annular fluid path formed between the inner cooling pipe 56 and the outer cooling pipe 55. Fresh water flows in this channel, absorbing the heat of the drilling fluid in the inner cooling pipe 56 and transferring it to the external cooling medium. Drilling fluid inlet and outlet are interfaces located on the casing, used to introduce high-temperature drilling fluid into the first fluid channel and to discharge cooled drilling fluid. Freshwater inlet and outlet are interfaces located on the casing, used to introduce freshwater into the second fluid channel and to discharge the heat-exchanged freshwater. The external cooling circuit is a fluid channel on the outside of the tube bundle structure, used to introduce external cooling media. In subsea applications, this circuit is typically connected to the surrounding seawater, utilizing the low-temperature seawater as the final cooling medium.

[0029] External cooling medium refers to the fluid flowing in the external cooling circuit, such as low-temperature seawater from the deep sea, which lowers the temperature of the fluid inside the cooler by absorbing heat. The safety sealing barrier refers to the protective function provided by the second fluid channel. Under high external pressure, this freshwater channel isolates the internal drilling fluid from the external environment, preventing drilling fluid leakage and helping to balance internal and external pressures, protecting the integrity of the inner tubing.

[0030] The outer side of the tube bundle structure is also provided with an external cooling circuit for the flow of external cooling medium. This external cooling circuit can be formed by the remaining space inside the shell, or by setting additional guide plates or sleeves on the outside of the tube bundle structure. The external cooling medium exchanges heat with the external cooling pipe 55 through this circuit.

[0031] As a specific example, in deep-sea oil and gas drilling operations, the temperature of the drilling fluid returning from the well can reach as high as 120°C. Conventional cooling equipment on the jack-up drilling platform 1 is insufficient to effectively cool it below 80°C in the high temperatures of summer, posing a risk of overheating to surface pumps, valves, and other equipment. To address this issue, the drilling fluid mud cooler 49 described in this embodiment is deployed at a depth of 200 meters underwater, where the seawater temperature is stable at around 10°C and the water pressure is relatively high.

[0032] Specifically, high-temperature drilling fluid enters the cooler through the drilling fluid inlet and outlet and is guided to the first fluid channel in the tube bundle structure. This first fluid channel is formed by the inner cooling pipe 56, in which the drilling fluid flows axially. Simultaneously, fresh water enters the cooler through the fresh water inlet and outlet and is guided to the second fluid channel. This second fluid channel is an annular space between the inner cooling pipe 56 and the outer cooling pipe 55, in which the fresh water flows in the opposite direction to the drilling fluid, i.e., in a counter-current flow arrangement. On the outside of the tube bundle structure, the external cooling circuit is connected to the surrounding deep-sea water. The low-temperature seawater, as the external cooling medium, flows in the external cooling circuit and exchanges heat with the outer cooling pipe 55. Thus, the heat of the drilling fluid is first transferred to the fresh water in the second fluid channel through the wall of the inner cooling pipe 56, raising the temperature of the fresh water. Subsequently, the heat of the fresh water is transferred to the low-temperature seawater in the external cooling circuit through the wall of the outer cooling pipe 55, and the seawater is discharged after a slight temperature increase. Through this multi-stage heat exchange, the temperature of the high-temperature drilling fluid is effectively reduced.

[0033] In this process, the freshwater in the second fluid channel plays a crucial safety sealing barrier role. Because the cooler is under external high pressure, the pressure within the freshwater channel can be precisely controlled to maintain equilibrium with or slightly exceed the external seawater pressure. This not only helps protect the inner cooling pipe 56 from direct pressure from the external environment, but also ensures that if a minor leak occurs in the inner cooling pipe 56 due to fatigue or corrosion, the leaked drilling fluid will first enter the freshwater channel, rather than directly into the external seawater environment. The presence of the freshwater channel provides an additional layer of isolation for the drilling fluid, effectively preventing oil-based drilling fluid from polluting the marine environment and providing time for leak detection and treatment. The cooled drilling fluid returns to the jack-up drilling platform 1 through the drilling fluid outlet, its temperature reduced to a safe operating range, thus ensuring the normal operation of the surface equipment.

[0034] Based on the above examples, the drilling fluid mud cooler 49 in this embodiment is deployed deep underwater, effectively utilizing the low-temperature deep-sea seawater as an external cooling medium. Compared to the prior art using surface seawater for cooling on the bottom-mounted drilling platform 1, this embodiment avoids the problem of insufficient cooling capacity due to the high temperature of surface seawater in summer. For example, in the above example, the deep-sea seawater temperature of 10°C is much lower than the surface seawater temperature of 28-30°C in summer, providing a greater temperature difference and thus improving cooling efficiency. Secondly, this embodiment adopts a three-layer fluid channel design, namely drilling fluid, fresh water, and external cooling medium. This design not only achieves heat exchange, but more importantly, the fresh water in the second fluid channel provides a safe sealing barrier for the inner tube bundle under external high pressure. Plate heat exchangers in the prior art usually do not have such a multi-layer protective structure. When handling oil-based drilling fluids, leakage may directly lead to environmental pollution. The fresh water barrier mechanism of this embodiment ensures that even if the inner cooling pipe 56 leaks, the drilling fluid first enters the fresh water channel instead of being directly discharged into the ocean, enhancing the safety and environmental friendliness of the system operation.

[0035] Furthermore, the fluids in the first and second fluid channels flow in opposite directions, further optimizing heat exchange efficiency. This counter-flow design ensures that the temperature difference between the two fluids remains high throughout the heat exchange process, allowing the drilling fluid to be cooled to a lower temperature. This achieves better cooling performance with the same heat exchange area compared to some simple co-flow or cross-flow heat exchangers.

[0036] In summary, the drilling fluid mud cooler 49 of this embodiment overcomes the challenges of existing technologies in high-temperature drilling fluid cooling through its underwater deployment capability, multi-layer fluid channel design, and safety sealing barrier function, providing a reliable and environmentally friendly solution for deep-sea high-temperature oil and gas well drilling operations.

[0037] In a preferred embodiment, the accommodating space is divided into a high-temperature drilling fluid inflow chamber 50, a cooled drilling fluid outflow chamber 51, a fresh water inflow chamber 52, and a fresh water outflow chamber 53. The high-temperature drilling fluid inflow chamber 50 and the cooled drilling fluid outflow chamber 51 are respectively connected to the high-temperature drilling fluid inlet 44 and the cooled drilling fluid outlet 43. The fresh water inflow chamber 52 and the fresh water outflow chamber 53 are respectively connected to the fresh water inlet 47 and the fresh water outlet 48. The two ends of the second fluid channel are respectively connected to the fresh water inflow chamber 52 and the fresh water outflow chamber 53 to realize the distribution and convergence of fresh water. The two ends of all the internal cooling pipes 56 of the tube bundle structure are respectively connected to the high-temperature drilling fluid inflow chamber 50 and the cooled drilling fluid outflow chamber 51 to evenly distribute the high-temperature drilling fluid to each internal cooling pipe 56 and converge and discharge the cooled drilling fluid.

[0038] In this embodiment, by separating the high-temperature drilling fluid inflow chamber 50, the cooled drilling fluid outflow chamber 51, the fresh water inflow chamber 52, and the fresh water outflow chamber 53 in the enclosed housing space, and by establishing clear connection relationships between these chambers and the tube bundle structure and the corresponding inlets and outlets, the problem of uniform distribution and efficient flow of fluid in the multi-tube bundle cooler is solved.

[0039] Specifically, high-temperature drilling fluid is pumped to the drilling fluid mud cooler 49 by the high-temperature drilling fluid supply booster pump 27 through a hose (high-temperature drilling fluid supply hose 11) or pipeline (drilling fluid cooler pipeline unit 18); alternatively, the high-temperature drilling fluid enters the suction port (i.e., high-temperature drilling fluid pump inlet 70) of the drilling fluid mud pump 57 solely by gravity. The drilling fluid mud pump 57 pumps the high-temperature drilling fluid into the high-temperature drilling fluid inflow chamber 50 through the high-temperature drilling fluid inlet 44. This chamber serves as a distribution chamber, uniformly guiding the high-temperature drilling fluid to all the inner cooling pipes 56 of the tube bundle structure. Simultaneously, fresh water enters the fresh water inflow chamber 52 from the fresh water inlet 47. This chamber also serves as a distribution chamber, uniformly guiding the fresh water to all the second fluid channels of the tube bundle structure. Inside the tube bundle structure, the drilling fluid flows in the inner cooling pipes 56, and the fresh water flows in the second fluid channel between the inner cooling pipes 56 and the outer cooling pipes 55. The two flow in opposite directions, achieving efficient heat exchange. The cooled drilling fluid flows out from the inner cooling pipe 56, collects in the cooled drilling fluid outlet chamber 51, and then flows back to the surface drilling fluid purification chamber 6 through the cooled drilling fluid outlet 43. Correspondingly, the heat-exchanged fresh water flows out from the second fluid channel, collects in the fresh water outlet chamber 53, and is discharged through the fresh water outlet 48. This sophisticated fluid management mechanism ensures that each inner cooling pipe 56 and each second fluid channel are fully utilized, avoiding fluid short-circuiting, uneven flow, or dead zones, thereby significantly improving the heat exchange efficiency and cooling uniformity of the entire drilling fluid mud cooler 49.

[0040] In a preferred embodiment, multiple baffles are arranged at intervals along the axis perpendicular to the tube bundle in the external cooling circuit, and the flow direction of the external cooling medium is opposite to the flow direction of the drilling fluid in the tube bundle.

[0041] In this embodiment, baffles are components installed within the fluid channel to change the fluid flow direction, increase fluid turbulence, and extend the fluid path. These baffles can take various forms; for example, they can be arc-shaped baffles, with their edges maintaining a certain gap with the inner wall of the shell or the outer wall of the tube bundle to force the fluid to change its flow direction multiple times; they can also be disc-shaped or annular baffles, arranged in an alternating pattern to form S-shaped or Z-shaped flow paths; or they can be rod-type baffles, using the arrangement of rods to guide fluid flow. By arranging multiple baffles at intervals perpendicular to the tube bundle axis within the external cooling circuit, the external cooling medium is forced to form a tortuous flow path outside the tube bundle, significantly increasing the turbulence of the fluid and the contact time with the tube bundle, effectively avoiding short-circuit flow of the cooling medium and ensuring full utilization of the heat exchange area. Simultaneously, the flow direction of the external cooling medium is designed to be opposite to that of the drilling fluid within the tube bundle. This counter-current arrangement maximizes the average temperature difference between the two fluids, allowing heat to be transferred more efficiently from the drilling fluid to the fresh water, and then from the fresh water to the external cooling medium. Through the turbulence effect of the baffles and the synergy of counter-current heat exchange, the external cooling circuit can remove heat more evenly and efficiently, thereby improving the overall heat exchange performance of the entire cooler and providing a stable low-temperature environment for the internal freshwater barrier.

[0042] refer to Figure 6 The present invention also provides an underwater cooler module 15, which is used to cool the high-temperature drilling fluid in the drilling fluid mud cooler 49 by being submerged in water, thereby surrounding the module with cold seawater at or near the seabed 3. Compared with conventional plate-type drilling fluid cooling systems, the present invention requires only limited energy consumption and pump pressure and head to pump a large amount of seawater through the cooling chamber; while in conventional plate-type drilling fluid cooling systems, seawater must be drawn from directly below the sea surface 2 and pumped to the cooler on the drilling rig deck through a pipe system with limited size, requiring higher pump pressure and head.

[0043] Therefore, this application proposes an underwater cooler module 15, including the aforementioned drilling fluid mud cooler 49, and also includes a freshwater circulation system. The freshwater circulation system includes a freshwater cooling water unit 64 connected to a freshwater outlet 48 and a freshwater inlet 47, a freshwater loop expansion tank 66 connected to the freshwater cooling water unit 64, and an environmental pressure compensator 67 connected to the freshwater loop expansion tank 66. The environmental pressure compensator 67 is connected to the environmental seawater pressure 68. The freshwater cooling water unit 64 is connected to a freshwater cooling pump 59, and the freshwater cooling pump 59 delivers freshwater to the freshwater inflow chamber 52 through the freshwater inlet 47.

[0044] In this embodiment, the freshwater inlet 63 of the freshwater cooling water unit 64 is connected to the freshwater cooling pump 59. The freshwater cooling pump 59 delivers freshwater through the freshwater inlet 47 to the freshwater inflow chamber 52. After absorbing heat from the drilling fluid in the second fluid channel, the freshwater returns to the freshwater cooling water unit 64 through the freshwater outlet 48 for cooling. The freshwater loop expansion tank 66 is used to accommodate volume fluctuations in the freshwater caused by temperature changes. The environmental pressure compensator 67 monitors and adjusts the freshwater loop pressure in real time to dynamically balance it with the external seawater pressure, thereby maintaining stable flow of freshwater in the tube bundle structure. By using freshwater as an intermediate cooling medium, a dual heat exchange mechanism is achieved. The heat from the drilling fluid is first transferred to the freshwater, and then transferred from the freshwater to the low-temperature seawater in the external cooling loop, avoiding direct contact between the drilling fluid and the high-temperature surface seawater. Because the environmental pressure compensator 67 automatically matches the external seawater pressure, the sealing integrity of the freshwater circuit is ensured in the underwater high-pressure environment. This ensures that the closed-loop freshwater circulation system maintains hydrostatic pressure balance with the environmental seawater pressure 68 during descent and operation, effectively preventing freshwater leakage or deformation of the pipe bundle structure due to pressure imbalance. Furthermore, the freshwater cooling water unit 64 can independently control the freshwater temperature, making it unaffected by seasonal temperature fluctuations of the surface seawater, thereby maintaining stable cooling efficiency.

[0045] Preferably, the freshwater contains corrosion inhibitors and anti-biofouling agents. In the high-pressure environment of the deep sea, the metal tube walls of the tube bundle structure are subjected to long-term dual erosion from corrosive fluids and seawater. They are also prone to biofouling due to the attachment of marine microorganisms, which can clog flow gaps and reduce heat exchange efficiency. Adding corrosion inhibitors and anti-biofouling agents to the freshwater, which serves as the intermediate medium, can form a protective film on the inner walls of the inner and outer cooling tubes 55, slowing down the corrosion rate of the tube walls and extending the service life of the cooler. Simultaneously, it inhibits the attachment and growth of marine microorganisms in the second fluid channel, preventing channel blockage, ensuring smooth freshwater flow, and maintaining long-term stable heat exchange efficiency.

[0046] Preferably, the freshwater cooling unit 64 is connected to a leak sensor 65. Since the drilling fluid is isolated by the freshwater in the second fluid channel, once the inner cooling pipe 56 leaks, the leaked drilling fluid will directly enter the freshwater circulation system. The leak sensor 65 can detect the drilling fluid components mixed in the freshwater in a timely manner and quickly issue a leak warning, which facilitates the operator to take timely measures such as shutdown and maintenance, avoid further expansion of the leak and environmental pollution, and improve the system's safety warning capability.

[0047] In a preferred embodiment, the underwater cooler module 15 further includes a seawater cooling system, which includes a seawater cooling pump 58 and a seawater suction filter 60 connected to the seawater cooling pump 58. The drilling fluid mud cooler 49 also includes a seawater cooling chamber 54 that forms an external cooling circuit. The seawater cooling chamber 54 is provided with a seawater inlet 45 connected to the seawater cooling pump 58 and a seawater outlet 46 connected to the warm seawater discharge pipeline 62. The seawater cooling chamber 54 is provided with an oil leak sensor 69 and an oil leak connector.

[0048] In this embodiment, the seawater cooling pump 58 drives the flow of seawater in the seawater cooling system, ensuring sufficient flow for efficient heat exchange. A seawater intake filter 60 is installed at the intake end of the seawater cooling pump 58 to remove impurities, particulate matter, and marine organisms from the seawater, preventing them from entering the cooling system and protecting the pump and other components from wear and clogging, ensuring stable system operation. This filter can be a mesh filter, basket filter, or self-cleaning filter. The seawater cooling chamber 54 is a key component of the external cooling circuit in the drilling fluid mud cooler 49, used to contain the seawater cooling medium and exchange heat with the second fluid channel in the tube bundle structure. This chamber is typically designed as a cavity surrounding the tube bundle structure, with an internal structure that optimizes fluid distribution to improve heat exchange efficiency. The warm seawater discharge line 62 discharges the heated seawater from the seawater cooling chamber 54 after heat exchange and back to the external environment from the warm seawater discharge outlet 61, thus diverting the seawater heated by the drilling fluid within the cooler away from the seawater intake filter 60 to ensure that the seawater entering the cooler maintains its original temperature. The oil leak sensor 69 is used to monitor in real time for oil leaks inside the seawater cooling chamber 54. In an underwater environment, the oil leak sensor 69 can more easily detect any leaks in the underwater cooler module 15. Any oil leak can pollute the marine environment, therefore, the placement of this sensor is crucial for environmental protection and system safety. The sensor can employ various detection principles, such as optical, electrochemical, or ultrasonic. The oil leak connector provides an interface for collecting or discharging the leak detected by the oil leak sensor 69 for further analysis, treatment, or cleanup. This connector can be a simple sampling port, a discharge port with a valve, or an interface connected to an oil leak collection container.

[0049] To efficiently dissipate the heat absorbed by the freshwater circulation system, a seawater cooling system provides external cooling. Specifically, a seawater cooling pump 58 draws seawater from the external environment and pre-purifies it through a seawater intake filter 60 to prevent impurities from entering the system. The purified seawater enters the seawater cooling chamber 54 inside the drilling fluid mud cooler 49 through the seawater inlet 45. This seawater cooling chamber 54 constitutes an external cooling loop, designed to allow for sufficient heat exchange between the seawater and the second fluid channel in the tube bundle structure. During the heat exchange, the freshwater in the freshwater circulation system transfers heat to the seawater, thereby lowering the freshwater temperature and achieving re-cooling. The cooled freshwater is then pumped back to the freshwater inlet chamber 52 by the freshwater cooling pump 59 to continue participating in the cooling cycle of the drilling fluid. The seawater, now at a higher temperature after heat exchange, is discharged back to the external environment through the warm seawater discharge pipeline 62. In this process, the second fluid channel, sandwiched between the first fluid channel and the external cooling loop, provides a safe sealing barrier for the inner tube bundle, effectively isolating the drilling fluid from the external seawater and preventing direct contact. In addition, the seawater cooling chamber 54 is equipped with an oil leak sensor 69 and an oil leak connector to monitor for oil leaks in real time. In the event of a leak, the oil leak sensor 69 will issue an alarm promptly, and the leaked material will be handled through the oil leak connector, effectively preventing pollution of the marine environment and ensuring the environmental friendliness and safety of underwater operations. In this way, the solution proposed in this application not only achieves efficient cooling of the drilling fluid but also provides reliable external heat dissipation and environmental safety assurance under high-pressure underwater conditions.

[0050] In other embodiments, this application also proposes a subsea drilling fluid mud cooling system, which includes the aforementioned subsea cooler module 15, a platform-side drilling fluid circulation unit, a power control umbilical cable 14, and a drilling fluid delivery assembly, wherein the drilling fluid delivery assembly is configured to be selectively assembled between a first configuration and a second configuration. The first configuration includes at least two flexible hoses to connect the platform-side circulation unit to the drilling fluid inlet and outlet of the subsea drilling fluid mud cooler 49. The second configuration includes a drilling fluid cooler piping unit 18, which integrates at least two rigid pipes to establish a rigid connection between the platform-side circulation unit and the drilling fluid inlet and outlet of the subsea drilling fluid mud cooler 49. The power control umbilical cable 14 maintains a connection between the platform-side drilling fluid circulation unit and the subsea drilling fluid mud cooler 49 in both configurations. The platform-side drilling fluid circulation unit is compatible with both the first and second configurations on the same supply / return flow path. It is arranged on the bottom-mounted drilling platform 1 and is configured to output high-temperature drilling fluid underwater and recover cooled drilling fluid.

[0051] The core innovation of this embodiment lies in the selective assembly of drilling fluid delivery components in both flexible and rigid pipe configurations. By using a platform-side drilling fluid circulation unit that accommodates both configurations within the same flow path, the problem of increased equipment failure rates due to insufficient cooling of high-temperature drilling fluid upon return to the jack-up drilling platform 1 is solved. In shallow water operations, the first configuration of the flexible hose is easily deployed from the jack-up drilling platform to the seabed surface 3. In deep water operations, the second configuration of the rigid pipe can withstand high-pressure environments and is lowered to a suitable depth by the floating jack-up drilling platform. This design allows for effective cooling of the drilling fluid in the low-temperature underwater environment, avoiding the insufficient cooling capacity of conventional coolers on the jack-up drilling platform 1 due to excessively high surface seawater temperatures in summer.

[0052] Specifically, when the system is deployed in shallow water, the drilling fluid delivery components adopt the first configuration, i.e., using flexible hose connections. The jack-up drilling platform 1 is equipped with a drilling fluid supply hose winch 8 and a drilling fluid return hose winch 9 for deploying and retrieving the hoses. The deployment winch wire rope 13 is connected to the subsea cooler module 15 via a wire rope interface for lowering and retrieval. The platform-side drilling fluid circulation unit introduces hot drilling fluid through the high-temperature drilling fluid inlet valve 30 and the hot drilling fluid inlet connector 22. After being pressurized by the high-temperature drilling fluid supply booster pump 27, it is delivered to the subsea drilling fluid mud cooler 49 via a flexible hose. The cooled drilling fluid returns via the return hose to the drilling fluid cooling and buffer tank 23 of the platform-side drilling fluid circulation unit, and then flows into the working drilling fluid tank system.

[0053] When the system is deployed in deep water, the drilling fluid delivery assembly adopts a second configuration, namely, using the drilling fluid cooler piping unit 18. This piping unit integrates a high-temperature drilling fluid supply line 41 and a cooled drilling fluid return line 42, arranged in a parallel and non-coaxial eccentric configuration. The piping unit is rigidly connected to the modular interface joint 72 via the cooler piping lower connector 81 and suspended from the upper part by a tensioning unit 73. A power control umbilical cable 14 provides power and control signals to ensure the normal operation of the subsea cooler module 15. The platform-side drilling fluid circulation unit requires no modification and is directly compatible with this connection method, delivering the high-temperature drilling fluid to the subsea drilling fluid mud cooler 49 and recovering the cooled drilling fluid.

[0054] Through the above technical solution, this application achieves effective cooling of drilling fluid under different water depth conditions. In shallow water mode, the flexible hose adapts to the installation environment of the seabed surface 3, facilitating rapid deployment and retrieval; in deep water mode, the rigid pipeline resists the high pressure of the deep sea, ensuring structural stability. Both modes share the same platform-side drilling fluid circulation unit, simplifying system design and reducing operational complexity. This not only improves cooling efficiency, ensuring the drilling fluid temperature stably drops below the equipment design limit, but also reduces problems such as pump and valve seal failure and rheological runaway caused by insufficient cooling, significantly reducing maintenance costs and unplanned downtime.

[0055] In one embodiment, the interface of the power control umbilical cable 14 remains unchanged in both dual-mode operating conditions and is connected to the power control unit located at the bottom-mounted drilling platform 1.

[0056] In a preferred embodiment, the underwater cooler module 15 is equipped with a shallow water mode interface, which includes a high-temperature drilling fluid inlet connector and a cooled drilling fluid outlet connector for connecting the high-temperature drilling fluid supply hose 11 and the cooled drilling fluid return hose 12, respectively, and a wire rope interface for connecting the laying winch wire rope 13. The bottom-mounted drilling platform 1 is equipped with a drilling fluid supply hose winch 8 and a drilling fluid return hose winch 9 for connecting the high-temperature drilling fluid supply hose 11 and the cooled drilling fluid return hose 12, respectively, and a lowering and recovery unit 10 for connecting the laying winch wire rope 13.

[0057] In this embodiment, the shallow water mode interface is a set of mechanical and fluid connection points specifically designed to facilitate the connection and deployment operations between the subsea cooler module 15 and the jack-up drilling platform 1 when operating in relatively shallow water. Its main function is to simplify the module deployment, retrieval, and fluid and mechanical connection processes in shallow water operations, thereby improving operational efficiency and safety.

[0058] The high-temperature drilling fluid inlet connector (installed at the high-temperature drilling fluid inlet 44) and the cooled drilling fluid outlet connector (installed at the cooled drilling fluid outlet 43) are fluid connection components on the shallow water interface. They are used to quickly and reliably connect to the high-temperature drilling fluid supply hose 11 and the cooled drilling fluid return hose 12 on the platform side, respectively, ensuring the safe and efficient transport of drilling fluid between the platform and the subsea module, while preventing leakage. These connectors can use quick-connect couplings (such as clamp couplings or threaded couplings) or flange connections, and are integrated with sealing mechanisms (such as O-rings or lip seals) to ensure fluid tightness. They are specifically designed to connect with the wire rope used by the deployment winch on the surface platform, enabling the subsea cooler module 15 to be precisely lowered, positioned, and retrieved via the wire rope. The lowering and retrieval unit 10, which is used to connect the wire rope 13 of the lowering winch, is a device installed on the bottom-mounted drilling platform 1. It is used to operate the connection and connection of the wire rope 13 of the lowering winch, realize the precise lowering, positioning and safe retrieval of the subsea cooler module 15, provide precise control over the vertical movement of the module, ensure the stable deployment and retrieval of the module in the underwater environment, and cope with changes in sea state.

[0059] In one specific embodiment, the main components of the lowering and retrieval unit 10 include a power and control umbilical cable winch 17, a lowering winch wire rope 13, an umbilical cable pulley 95, a cable pulley 94, and a set of lowering and retrieval device cylinders 93.

[0060] In one specific embodiment, the main components of the drilling fluid supply hose winch 8 and the drilling fluid return hose winch 9 include: hose reel 88, hose winch power unit 90, hose reel 89, hose bending limit device 92, oil receiving tray device 91, and drilling fluid return and supply connector (for connecting the cooled drilling fluid return pipeline 25 / high temperature drilling fluid supply pipeline 28).

[0061] Therefore, the main components of the underwater cooler module 15 in shallow water mode include: drilling fluid mud cooler 49, drilling fluid mud pump 57, environmental pressure compensator 67 with oil leak sensor 69, fresh water cooling pump 59, seawater cooling pump 58, fresh water cooling water unit 64; and other conventional components, such as valves, expansion tanks, compensators, sensors, and seabed electronic units with control circuits, etc. The above components will not be described in detail here.

[0062] This implementation achieves convenient and safe deployment and retrieval of the subsea cooler module 15 in shallow water by configuring a shallow-water interface and installing corresponding drilling fluid supply hose winches 8, drilling fluid return hose winches 9, and a lowering and recovery unit 10 on the bottom-mounted drilling platform 1, thus establishing a reliable fluid connection. During the module lowering process, the lowering and recovery unit 10 precisely controls the vertical movement of the module through a wire rope interface, positioning it to the predetermined location. Once the module is in place, the drilling fluid supply hose winches 8 and 9 work together to deploy and connect the corresponding flexible hoses to the fluid connectors on the module, establishing the drilling fluid pathway. During retrieval, the above process is reversed. This integrated interface design, combined with the platform-side dedicated deployment and hose management equipment, enables the deployment, fluid connection, and retrieval of the subsea cooler module 15 in shallow water environments to be completed efficiently and safely, effectively solving the challenges of module deployment and fluid connection in flexible connection mode.

[0063] In a preferred embodiment, the subsea cooler module 15 is equipped with a deep-water mode interface, which includes a modular interface connector 72 with a flexible joint 71. The modular interface connector 72 integrates a high-temperature drilling fluid supply pipeline 41 and a cooled drilling fluid return pipeline 42. The bottom-mounted drilling platform 1 is provided with a pipeline unit load suspension module 16 and a mud pad module 20 with a guide cable 19 for connecting the subsea cooler module 15 and the pipeline unit load suspension module 16.

[0064] In this embodiment, the deepwater mode interface is a connection interface specifically designed for deepwater environments. It aims to ensure the reliability of the fluid and control connections between the subsea cooler module 15 and the bottom-mounted drilling platform 1, to cope with the high static water pressure and dynamic loads in deep water. This interface can be modularly designed, allowing for the selection of different connection types based on specific deepwater deployment scenarios, or integrating remote operation and monitoring functions. The modular interface connector 72 with flexible joint 71 is an interface connector containing flexible elements. Its function is to allow a certain degree of angular misalignment or relative movement between the cooling module and the connecting piping unit, thereby effectively absorbing dynamic loads, thermal expansion and contraction, and installation errors in deepwater environments, preventing stress concentration at rigid connections, and ensuring the integrity of the connection. The flexible joint 71 can be a ball joint, a rotary joint, or a reinforced flexible hose integrated into a rigid connector, or a bellows-type expansion joint designed to absorb axial and angular displacements. The subsea cooler module 15 is also equipped with a high-temperature drilling fluid subsea jumper hose 78 and a cooled drilling fluid subsea jumper hose 77. These are short, flexible hoses used for deepwater interface connections. They provide localized flexibility, facilitating connection / disconnection operations, accommodating slight alignment misalignments, and absorbing vibrations or minor displacements between rigid components in deepwater environments, ensuring smooth fluid transfer between different parts of the deepwater interface. These hose jumpers can be high-pressure, high-temperature resistant composite hoses or wire-reinforced rubber hoses designed specifically for subsea applications, or dedicated armored flexible piping capable of withstanding external pressure and internal fluid characteristics. The modular interface connector 72 integrates a high-temperature drilling fluid supply line 41 and a cooled drilling fluid return line 42. This integrated design simplifies the connection process, reduces the number of external connection points, and enhances the overall structural integrity and compactness of the deepwater interface, thereby minimizing potential leakage points and simplifying deployment. This integration can be achieved by machining internal channels within the solid block of the interface joint, or by embedding prefabricated pipe sections into the joint structure during manufacturing, or by employing a manifold design to combine multiple fluid paths within a robust housing. The piping unit load suspension module 16, mounted on the jack-up drilling platform 1, functions to provide the necessary structural support and lifting capacity for the heavy-duty drilling fluid cooler piping unit 18 during deepwater deployment and retrieval, ensuring controlled operation and preventing excessive stress on the piping unit and cooling module. The mud pad module 20 provides a stable foundation for the subsea cooler module 15 on the seabed, preventing it from sinking into soft mud deposits. The integrated guide cable 19 facilitates precise alignment and connection of the drilling fluid cooler piping unit 18 from the platform to the subsea cooling module in deepwater environments, especially under conditions of low visibility and challenging precision operation.Specifically, the guide cable 19 has a guide post, and the guide cable 19 can extend the mud pad module 20 to the water surface through the guide cable winch 75, and cooperate with the pipeline unit load suspension module 16 or the guide funnel of the pipeline unit itself to ensure guided descent and docking.

[0065] This application's solution provides a specialized solution for deploying the subsea cooler module 15 in deep-water environments through the configuration of a deep-water mode interface. The modular interface connector 72 with a flexible joint 71 effectively absorbs unavoidable dynamic loads and installation deviations during deep-water operations, avoiding stress concentration problems that may arise from rigid connections, thus ensuring long-term reliability of the connection. The inclusion of a high-temperature drilling fluid subsea jumper hose 78 and a cooled drilling fluid subsea jumper hose 77 further enhances the local flexibility of the connection, simplifies subsea connection operations, and effectively buffers vibration. The modular interface connector 72 integrates a high-temperature drilling fluid supply line 41 and a cooled drilling fluid return line 42, significantly reducing the number of subsea connection points, improving the overall compactness and sealing of the system, and reducing the risk of leakage. On the jack-up drilling platform 1, the configuration of the pipeline unit load suspension module 16 allows for precise control of the deployment and retrieval process of the heavy-duty drilling fluid cooler pipeline unit 18, preventing damage to the equipment. Furthermore, the mud pad module 20 with guide cable 19 not only provides stable seabed support for the subsea cooler module 15, but its guide cable 19 also provides reliable guidance for the precise docking of the pipeline unit, greatly improving the efficiency and safety of deep-water installation operations. Through the synergistic effect of the above components, the load absorption requirements of the drilling fluid pipeline unit are met, effectively solving the complex technical challenges of rigid pipeline connections and heavy equipment deployment in deep-water environments.

[0066] In a preferred embodiment, the high-temperature drilling fluid supply pipeline 41 and the cooled drilling fluid return pipeline 42 are arranged eccentrically and non-coaxially within the drilling fluid cooler pipeline unit 18, and are tightly secured to the outside of the high-temperature drilling fluid supply pipeline 41 and the cooled drilling fluid return pipeline 42 by the cooler pipeline clamping unit 84, in order to maintain the relative position and parallelism of the two pipelines.

[0067] In this embodiment, the cooler pipe clamping unit 84 is a mechanical device for fixing the pipeline. It tightly fixes the high-temperature drilling fluid supply pipeline 41 and the cooled drilling fluid return pipeline 42 inside the drilling fluid cooler pipe unit 18 by wrapping around them. This clamping unit can consist of a series of segmented metal clamps, which are fixed to the inner wall of the drilling fluid cooler pipe unit 18 by bolts or welding. Alternatively, the clamping unit can be an integral bushing made of elastic material with grooves that match the shape of the pipeline, fixing the pipeline by compression or bonding. By eccentrically arranging the high-temperature drilling fluid supply pipeline 41 and the cooled drilling fluid return pipeline 42 in parallel and non-coaxial configurations within the drilling fluid cooler pipe unit 18, and using the cooler pipe clamping unit 84 to wrap around and secure them externally, a stable and compact integrated pipeline assembly is formed. This design ensures that the two pipes maintain precise relative position and parallelism along their entire length, effectively preventing relative movement, vibration, or deformation that may occur during deepwater deployment, retrieval, and long-term operation. In this way, the piping system can better resist external water flow impacts, dynamic loads caused by platform movement, and stresses from internal fluid pressure changes, ensuring the reliability and sealing of the pipe connections. This integration, combined with the deepwater mode interface in the subsea drilling fluid mud cooling system, provides a more robust and reliable drilling fluid delivery channel for deepwater drilling operations, significantly improving the operational stability and safety of the entire cooling system.

[0068] In a preferred embodiment, the drilling fluid cooler piping unit 18 includes a lower cooler pipe connector 81 and an upper cooler pipe connector 80. The high-temperature drilling fluid supply pipe 41 and the cooled drilling fluid return pipe 42 are connected to the lower cooler pipe connector 81 and the upper cooler pipe connector 80. The lower cooler pipe connector 81 includes a flange and a bolt assembly 87 fastened to the flange. The lower cooler pipe connector 81 is detachably rigidly connected to the modular interface connector 72 through the bolt assembly 87. The upper cooler pipe connector 80 is suspended by a tensioning unit 73. The upper cooler pipe connector 80 includes a high-temperature drilling fluid sealing short section 85 and a cooled drilling fluid sealing short section 86 spaced apart. The high-temperature drilling fluid sealing short section 85 is coaxially sealed with the high-temperature drilling fluid supply pipe 41, and the cooled drilling fluid sealing short section 86 is coaxially sealed with the cooled drilling fluid return pipe 42.

[0069] In this embodiment, the drilling fluid cooler piping unit 18 serves as a key component connecting the subsea drilling fluid cooler module and the platform-side drilling fluid circulation unit. It integrates a high-temperature drilling fluid supply pipe 41 and a cooled drilling fluid return pipe 42. To ensure reliable operation of this unit in deep-water, high-pressure environments, this application solves the challenges of pipe connection and sealing through ingenious connection and sealing design. Specifically, the cooler pipe lower connector 81 of the drilling fluid cooler piping unit 18, through its included flange and bolt assembly 87, achieves a detachable rigid connection with the modular interface connector 72. This rigid connection provides a stable bottom support for the entire piping unit, enabling it to withstand the impact of the external environment and the pressure of the internal fluid. Simultaneously, the detachability facilitates subsequent maintenance and replacement. At the top of the piping unit, the cooler pipe upper connector 80 is suspended by a tensioning unit 73. This suspension method allows the piping unit to adapt to minor displacements caused by changes in the external environment or internal fluid temperature to a certain extent, avoiding excessive stress concentration. More importantly, the upper connector 80 of the cooler pipeline is internally equipped with high-temperature drilling fluid sealing sections 85 and cooled drilling fluid sealing sections 86. These sealing sections are coaxially sealed with the high-temperature drilling fluid supply pipeline 41 and the cooled drilling fluid return pipeline 42, respectively. This coaxial sealing ensures complete isolation of the two drilling fluids in their respective pipelines, effectively preventing cross-flow between the high-temperature drilling fluid and the cooled drilling fluid, and also avoiding drilling fluid leakage to the external environment. Through the rigid connection of the lower connector and the suspension and precision sealing of the upper connector, the entire drilling fluid cooler pipeline unit 18 achieves reliable internal fluid delivery and sealing while maintaining structural stability, thereby ensuring the efficient and safe operation of the subsea drilling fluid mud cooling system in deep water mode.

[0070] In one specific embodiment, the main components of the tensioning unit 73 include a set of tensioning cylinders 83 and a set of compensator accumulators 82. A drilling fluid diversion head 74 is installed on the top of the connector 80 on the cooler pipeline. The drilling fluid diversion head 74 includes a crane lug flange 79 for connection to the deck crane 7, a high-temperature drilling fluid supply line 28, and a cooled drilling fluid return line 25. The deck crane 7 is used to connect new pipe sections of the drilling fluid cooler pipeline unit 18 and suspend them on the pipeline unit load suspension module 16.

[0071] In a preferred embodiment, the platform-side drilling fluid circulation unit includes: Drilling fluid cooling and buffer tank 23; A high-temperature drilling fluid supply booster pump 27 is connected to the drilling fluid cooling and buffer tank 23. The suction port of the high-temperature drilling fluid supply booster pump 27 is connected to a high-temperature drilling fluid shut-off valve 34, which is used to deliver the high-temperature drilling fluid downward to the underwater drilling fluid mud cooler 49 in the submerged state. The high-temperature drilling fluid inlet valve 30 and the hot drilling fluid inlet connector 22, which are connected to the drilling fluid cooling and buffer tank 23, are used to introduce and pressurize the hot drilling fluid in the surface drilling fluid purification chamber 6. A cooled drilling fluid return line 25 with a drilling fluid flow meter 26 is connected to the drilling fluid cooling and buffer tank 23 for precise control of the cooled drilling fluid flow rate. The system includes a cooled drilling fluid return inlet valve 33 and a drilling working fluid system connector 38, which allow the cooled drilling fluid to flow smoothly into the working drilling fluid tank system.

[0072] In this embodiment, the drilling fluid cooling and buffer tank 23 is used to receive hot drilling fluid from the surface drilling fluid purification chamber 6 and serves as a buffer container for the drilling fluid before it enters the submersible cooler. The drilling fluid cooling and buffer tank 23 has a dual purpose: firstly, to supply high-temperature drilling fluid to the submersible cooler module 15 while it is submerged; secondly, after the module is placed on the seabed 3, to use drilling water to replace the seawater in the drilling fluid supply and return hoses or drilling fluid cooler piping unit 18 with the seawater in the submersible cooler module 15; and after the drilling fluid cooling operation is completed and before the system is recovered from the seabed 3 to the bottom-mounted drilling platform 1, to replace the oil-based drilling fluid in the circulation system and the submersible cooler module 15.

[0073] Specifically, the high-temperature drilling fluid supply booster pump 27 is used to increase the pressure of the high-temperature drilling fluid, enabling it to overcome the hydrostatic pressure and pipeline resistance caused by the underwater depth, thereby effectively delivering the high-temperature drilling fluid to the subsea drilling fluid mud cooler 49. The high-temperature drilling fluid shut-off valve 34 is located at the suction inlet of the high-temperature drilling fluid supply booster pump 27, used to completely cut off the supply of high-temperature drilling fluid when needed, achieving pump isolation protection or system maintenance. The high-temperature drilling fluid inlet valve 30 is used to control the flow rate of hot drilling fluid from the surface drilling fluid purification chamber 6 into the drilling fluid cooling and buffer tank 23, and can be isolated when needed. The hot drilling fluid inlet connector 22 is the interface connecting the platform-side drilling fluid circulation unit and the surface drilling fluid purification chamber 6, used for convenient and reliable introduction of hot drilling fluid. A cooled drilling fluid return line 25, equipped with a drilling fluid flow meter 26, is used to transport cooled drilling fluid returned from the subsea drilling fluid mud cooler 49 to the platform side. It also integrates the drilling fluid flow meter 26 to monitor the flow rate of the returned drilling fluid in real time. A cooled drilling fluid return inlet valve 33 controls the flow rate of cooled drilling fluid into the working drilling fluid tank system and can isolate the return line when necessary. The drilling working fluid system connector 38 is the connection interface between the platform-side drilling fluid circulation unit and the working drilling fluid tank system, used to safely and smoothly return the cooled drilling fluid to the main drilling fluid system.

[0074] Through the above technical solutions, the platform-side drilling fluid circulation unit can achieve refined management of the drilling fluid circulation process. The high-temperature drilling fluid supply booster pump 27, in conjunction with the high-temperature drilling fluid shut-off valve 34, ensures that the high-temperature drilling fluid can be stably and safely delivered to the submerged cooler under submerged conditions, effectively overcoming the pressure challenges of deep-water environments. The drilling fluid cooling and buffer tank 23, along with the high-temperature drilling fluid inlet valve 30 and inlet connector, allows for the effective introduction, buffering, and stable supply of hot drilling fluid from the surface purification chamber, preventing system fluctuations. Simultaneously, the cooled drilling fluid return pipeline 25, equipped with a drilling fluid flow meter 26, along with the cooled drilling fluid return inlet valve 33 and the working drilling fluid system connector, enables precise monitoring and controlled return of the cooled drilling fluid flow rate, ensuring that the cooled drilling fluid can smoothly and efficiently return to the working drilling fluid tank system. This significantly improves the operational stability, control accuracy, and operational safety of the entire submerged drilling fluid mud cooling system, effectively solving the complex problems in platform-side drilling fluid management.

[0075] As a preferred embodiment, the platform-side drilling fluid circulation unit also includes a drilling water flushing pipeline joint 31 and a drilling water flushing valve 32. When the high-temperature drilling fluid inlet valve 30 is closed, the drilling water can flow into the drilling fluid cooling and buffer tank 23 through the drilling water flushing valve 32.

[0076] In this embodiment, the drilling water flushing pipeline connector 31 is an interface for connecting to an external drilling water supply pipeline. It can be designed as a quick-connect coupling for easy on-site connection and disconnection of the flushing water pipeline. The drilling water flushing valve 32 is used to control the flow rate and on / off state of the drilling water in the flushing pipeline. It can be a manual ball valve, which is easy to operate and has a low cost; or it can be an electric or pneumatic shut-off valve to achieve remote control and automated operation, improving the accuracy and safety of the flushing process.

[0077] When flushing the drilling fluid cooling and buffer tank 23 is required, the high-temperature drilling fluid inlet valve 30 is first closed. This isolates the drilling fluid cooling and buffer tank 23 from the hot drilling fluid supply pipeline from the surface drilling fluid purification chamber 6, preventing unnecessary mixing of the flushing water with the circulating drilling fluid or impacting the upstream system. Subsequently, external drilling water is introduced through the drilling water flushing pipeline joint 31, and the drilling water flushing valve 32 is opened, allowing the drilling water to flow smoothly into the drilling fluid cooling and buffer tank 23. The drilling water flowing inside the tank flushes and dilutes or removes any residual drilling fluid that may remain inside the tank and in the pipelines connected to it. This design allows the platform-side drilling fluid circulation unit to be conveniently and safely cleaned internally after completing the drilling fluid cooling task, facilitating subsequent maintenance, repairs, or switching between different types of drilling fluids. In this way, the solution is closely integrated with the existing structure of the platform-side drilling fluid circulation unit (such as the drilling fluid cooling and buffer tank 23 and the high-temperature drilling fluid inlet valve 30) to form a complete and maintainable drilling fluid treatment loop.

[0078] In a preferred embodiment, the platform-side drilling fluid circulation unit also includes a flushing bypass valve 37, a delivery valve 36, a drilling fluid working tank delivery pump 24, a vent valve 39, and a discharge pipeline connector 40, which are used to discharge the displacement water in the cooling circuit when the cooling-out drilling fluid return inlet valve 33 is closed.

[0079] In this embodiment, a dedicated pipeline and control components for displacement water discharge are added to the platform-side drilling fluid circulation unit, resolving the issue of residual displacement water in the cooling circuit. When maintenance, cleaning, or drilling fluid replacement of the cooling circuit is required, the cooled drilling fluid return inlet valve 33 is first closed to isolate the main drilling fluid circulation circuit and prevent the displacement water from mixing with the drilling fluid. In this isolated state, the cooling circuit is connected to the discharge pipeline connected to the discharge pipeline joint 40 by opening the flushing bypass valve 37 and the delivery valve 36. The drilling fluid working tank delivery pump 24 is started, providing power to the displacement water in the cooling circuit, enabling it to overcome pipeline resistance and be forcibly discharged from the system via the discharge pipeline and the relief valve 39. This design allows the displacement water to be thoroughly and effectively removed from the cooling circuit, ensuring that the purity of the drilling fluid and cooling efficiency are not affected when the system is put back into use. By cooperating with the existing pipelines and valves of the platform-side drilling fluid circulation unit, this discharge system enables precise control and management of the cooling circuit, avoiding the problems of incomplete discharge or complex operation that may occur in traditional methods.

[0080] In one specific embodiment, before the system is recovered to the drilling rig, drilling replacement water is pumped to the high-temperature drilling fluid supply hose 11, the cooled drilling fluid cooling hose or the high-temperature drilling fluid supply line 41, the cooled drilling fluid return line 42, and the subsea cooler module 15 to circulate the oil-based mud out of the system and replace it with clean drilling water.

[0081] In one specific embodiment, the platform-side drilling fluid circulation unit also includes a cooling circuit test shut-off valve 35 and a cooling circuit pressure test connector 29. The cooling circuit test shut-off valve 35 is connected between the cooling circuit pressure test connector 29 and the cooling circuit. During system shutdown and maintenance, the shut-off valve is opened to connect to a pressure testing device for offline testing of the cooling circuit's sealing performance and pressure-bearing capacity. This allows for rapid completion of circuit pressure testing without disassembling existing pipeline interfaces, ensuring the safety and stability of the system's subsequent operation.

[0082] In one specific embodiment, the platform-side drilling fluid circulation unit is equipped with a power and control unit 21 in both operating modes.

[0083] When traditional drilling fluid coolers are installed on the deck of a jack-up drilling platform, the ambient temperature is high, and the surface seawater used as the cooling medium is also relatively hot, leading to poor cooling performance and a series of cooler operation problems. This also shortens the maintenance cycle and increases maintenance costs for drilling fluid purification, low-pressure, and high-pressure pumping equipment. To address this, the present invention provides a subsea drilling fluid mud cooling system. The core innovation lies in arranging and operating the subsea cooler module 15 in a seawater environment, aiming to efficiently cool the drilling fluid using the low-temperature seawater at a specific depth. This system employs a dual-mode design, suitable for both shallow and deep water environments, and applicable to both jack-up and floating jack-up drilling platforms. In deep-water applications, the cooling system can be lowered to a suitable depth in the seawater to utilize the sufficiently low seawater temperature for cooling; in shallow-water applications, it can be lowered to the seabed surface. In both of the above-mentioned operating modes, this system can operate safely under the motion loads of the jack-up drilling platform 1 and environmental loads such as waves, wind, and ocean currents. This invention can alleviate or eliminate several problems associated with conventional drilling fluid coolers used on jack-up drilling platforms 1 in high-temperature environments. Furthermore, to ensure safety during submerged operation in seawater, the drilling fluid mud cooler 49 of this invention is equipped with a protective barrier (freshwater circulation system) to prevent seawater pollution caused by oil-based drilling fluid leakage. Therefore, the subsea drilling fluid mud cooling system of this invention includes a platform-side drilling fluid circulation unit located on the jack-up drilling platform 1. The manifold of this platform-side drilling fluid circulation unit includes pipelines, pumps, valves, and instruments, and can be used for both shallow and deep water operations. The primary function of this subsea drilling fluid mud cooling system is for shallow water operations: under these conditions, due to the fast lowering speed, minimal interaction with the drilling rig system, and low environmental loads during lowering, retrieval, and operation, the subsea cooler module 15 is lowered to the shallow seabed 3 via a drilling fluid hose structure. The second function of the subsea drilling fluid mud cooling system is for deepwater operations: when the environmental load on the system is too high during the lowering, recovery and operation, the drilling fluid hose circulation structure is replaced by the drilling fluid cooler piping unit 18, which is designed specifically for deepwater operations.

[0084] In summary, this invention provides a subsea drilling fluid mud cooling system suitable for shallow water operations. It employs drilling fluid circulation hoses, such as a high-temperature drilling fluid supply hose 11 and a cooled drilling fluid return hose 12. These hoses are clamped together with the deployment winch wire rope 13 via hose clamps 76. This setup is feasible in terms of structural load and environmental adaptability, and can meet the requirements of applicable wave and current load conditions. The main components of the subsea drilling fluid mud cooling system suitable for shallow water conditions include: a lowering and recovery unit 10, a drilling fluid supply hose winch 8, a drilling fluid return hose winch 9, a high-temperature drilling fluid supply hose 11, a cooled drilling fluid return hose 12, a deployment winch wire rope 13, a power control umbilical cable 14, a subsea cooler module 15, and a drilling fluid mud pump 57. A mud pad module 20 is securely connected to the subsea cooler module 15, allowing the subsea cooler module 15 to sit on the seabed 3.

[0085] This invention provides a subsea drilling fluid mud cooling system suitable for deep-water operations. This system requires drilling fluid fittings, such as a high-temperature drilling fluid supply pipeline 41 and a cooled drilling fluid return pipeline 42, to meet the stringent load and operational requirements under corresponding wave and current conditions. The main components of the subsea drilling fluid mud cooling system for deep-water operations include: a pipeline unit load suspension module 16, a drilling fluid cooler pipeline unit 18, a mud pad module 20 with guide columns and guide cables 19, a subsea cooler module 15, and a power and control umbilical winch 17 equipped with a power control umbilical cable 14. A deck crane 7 is used to extend individual drilling fluid cooler pipeline units 18 and lower the subsea cooler module 15 and drilling fluid cooler pipeline units 18 into the seawater until they reach the seabed 3 or the desired operating depth.

[0086] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A drilling fluid mud cooler, characterized in that, include: A sealed shell, whose interior defines the space for containment; The tube bundle structure disposed within the accommodating space includes an inner cooling tube and an outer cooling tube coaxially sleeved together. A first fluid channel for drilling fluid to flow is formed inside the inner cooling tube, and a second fluid channel for fresh water to flow is formed between the inner cooling tube and the outer cooling tube. The drilling fluid inlet and outlet are provided on the shell and communicate with the first fluid channel, and the fresh water inlet and outlet are communicated with the second fluid channel. The fluid in the first fluid channel and the fluid in the second fluid channel are arranged to flow in opposite directions within the tube bundle structure. The outer side of the tube bundle structure is provided with an external cooling circuit for the flow of external cooling medium. The second fluid channel is sandwiched between the first fluid channel and the external cooling circuit, and is used to provide a safe sealing barrier for the inner tube bundle under external high pressure environment.

2. The drilling fluid mud cooler according to claim 1, characterized in that, The containment space is divided into a high-temperature drilling fluid inlet chamber, a cooled drilling fluid outlet chamber, a fresh water inlet chamber, and a fresh water outlet chamber. The high-temperature drilling fluid inlet chamber and the cooled drilling fluid outlet chamber are respectively connected to the high-temperature drilling fluid inlet and the cooled drilling fluid outlet. The fresh water inlet chamber and the fresh water outlet chamber are respectively connected to the fresh water inlet and the fresh water outlet. The two ends of the second fluid channel are respectively connected to the fresh water inlet chamber and the fresh water outlet chamber to realize the distribution and confluence of fresh water. The two ends of all the internal cooling pipes of the tube bundle structure are respectively connected to the high-temperature drilling fluid inlet chamber and the cooled drilling fluid outlet chamber to evenly distribute the high-temperature drilling fluid to each internal cooling pipe and to converge and discharge the cooled drilling fluid.

3. The drilling fluid mud cooler according to claim 1, characterized in that, Multiple baffles are arranged at intervals along the axis perpendicular to the tube bundle in the external cooling circuit, and the flow direction of the external cooling medium is opposite to the flow direction of the drilling fluid in the tube bundle.

4. An underwater cooler module, characterized in that, The drilling fluid mud cooler according to any one of claims 1-3 further includes a freshwater circulation system, wherein the freshwater circulation system includes a freshwater cooling water unit connected to a freshwater outlet and a freshwater inlet respectively, a freshwater loop expansion tank connected to the freshwater cooling water unit, and an environmental pressure compensator connected to the freshwater loop expansion tank, wherein the environmental pressure compensator is connected to the environmental seawater pressure, and the freshwater cooling water unit is connected to a freshwater cooling pump, wherein the freshwater cooling pump delivers freshwater to the freshwater inflow chamber through the freshwater inlet.

5. The underwater cooler module according to claim 4, characterized in that, It also includes a seawater cooling system, which includes a seawater cooling pump and a seawater suction filter connected to the seawater cooling pump. The drilling fluid mud cooler also includes a seawater cooling chamber that forms an external cooling circuit. The seawater cooling chamber is provided with a seawater inlet connected to the seawater cooling pump and a seawater outlet connected to a warm seawater discharge pipeline. The seawater cooling chamber is provided with an oil leak sensor and an oil leak connector.

6. A subsea drilling fluid mud cooling system, characterized in that, The subsea cooler module of claim 5 further includes a platform-side drilling fluid circulation unit, a power control umbilical cable, and a drilling fluid delivery assembly; the drilling fluid delivery assembly is configured to be selectively assembled between a first configuration and a second configuration. The first configuration includes at least two flexible hoses to connect the platform-side circulation unit to the drilling fluid inlet and outlet of the subsea drilling fluid mud cooler; The second form includes a drilling fluid cooler piping unit, which integrates at least two rigid pipes to establish a rigid connection between the platform-side circulation unit and the drilling fluid inlet and outlet of the subsea drilling fluid mud cooler. The power control umbilical cable remains connected to the platform-side drilling fluid circulation unit and the subsea drilling fluid mud cooler in both configurations. The platform-side drilling fluid circulation unit is compatible with both the first and second configurations on the same supply / return flow path. It is arranged on the bottom-mounted drilling platform and is configured to output high-temperature drilling fluid underwater and recover cooled drilling fluid.

7. The underwater drilling fluid mud cooling system according to claim 6, characterized in that, The submersible cooler module is equipped with a shallow water mode interface, which includes a high-temperature drilling fluid inlet connector and a cooled drilling fluid outlet connector for connecting the high-temperature drilling fluid supply hose and the cooled drilling fluid return hose, respectively, and a wire rope interface for connecting the laying winch wire rope. The bottom-mounted drilling platform is equipped with a drilling fluid supply hose winch and a drilling fluid return hose winch for connecting the high-temperature drilling fluid supply hose and the cooled drilling fluid return hose, respectively, and a lowering and recovery unit for connecting the laying winch wire rope.

8. The underwater drilling fluid mud cooling system according to claim 6, characterized in that, The subsea cooler module is equipped with a deep-water mode interface, which includes a modular interface connector with a flexible joint. The modular interface connector integrates a high-temperature drilling fluid supply pipeline and a cooled drilling fluid return pipeline. The bottom-mounted drilling platform is equipped with a pipeline unit load suspension module and a mud pad module with a guide cable for connecting the subsea cooler module and the pipeline unit load suspension module.

9. The underwater drilling fluid mud cooling system according to claim 8, characterized in that, The high-temperature drilling fluid supply pipeline and the cooled drilling fluid return pipeline are arranged eccentrically and non-coaxially within the drilling fluid cooler pipeline unit. They are also tightly secured to the outside of the high-temperature drilling fluid supply pipeline and the cooled drilling fluid return pipeline by the cooler pipeline clamping unit to maintain the relative position and parallelism of the two pipelines.

10. The underwater drilling fluid mud cooling system according to claim 9, characterized in that, The drilling fluid cooler piping unit includes a lower cooler pipe connector and an upper cooler pipe connector. The high-temperature drilling fluid supply pipe and the cooled drilling fluid return pipe are connected to the lower cooler pipe connector and the upper cooler pipe connector. The lower cooler pipe connector includes a flange and a bolt assembly fastened to the flange. The lower cooler pipe connector is detachably rigidly connected to a modular interface connector through the bolt assembly. The upper cooler pipe connector is suspended by a tensioning unit. The upper cooler pipe connector includes a high-temperature drilling fluid sealing short section and a cooled drilling fluid sealing short section spaced apart. The high-temperature drilling fluid sealing short section is coaxially sealed with the high-temperature drilling fluid supply pipe, and the cooled drilling fluid sealing short section is coaxially sealed with the cooled drilling fluid return pipe.

11. The underwater drilling fluid mud cooling system according to claim 6, characterized in that, The platform-side drilling fluid circulation unit includes: Drilling fluid cooling and buffer tanks; A high-temperature drilling fluid supply booster pump is connected to the drilling fluid cooling and buffer tank. The inlet of the high-temperature drilling fluid supply booster pump is connected to a high-temperature drilling fluid shut-off valve, which is used to deliver the high-temperature drilling fluid downward to the underwater drilling fluid mud cooler in the submerged state. The high-temperature drilling fluid inlet valve and hot drilling fluid inlet connector, which are connected to the drilling fluid cooling and buffer tank, are used to introduce and pressurize the hot drilling fluid in the water surface drilling fluid purification chamber. A cooled drilling fluid return line equipped with a drilling fluid flow meter is connected to the drilling fluid cooling and buffer tank for precise control of the cooled drilling fluid flow rate. In addition, there are cooling drilling fluid return inlet valves and working drilling fluid system connectors, which allow the cooled drilling fluid to flow smoothly into the working drilling fluid tank system.

12. The underwater drilling fluid mud cooling system according to claim 11, characterized in that, The platform-side drilling fluid circulation unit also includes a drilling water flushing pipeline joint and a drilling water flushing valve. When the high-temperature drilling fluid inlet valve is closed, the drilling water can flow into the drilling fluid cooling and buffer tank through the drilling water flushing valve.

13. The underwater drilling fluid mud cooling system according to claim 11, characterized in that, The platform-side drilling fluid circulation unit also includes a flushing bypass valve, a vent valve, a drilling fluid working tank delivery pump, and a discharge pipeline connector, which are used to discharge the displacement water in the cooling circuit when the cooling drilling fluid return inlet valve is closed.

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