A drilling cooling device and a drilling cooling method

Abstract

The application provides a drilling cooling device and a drilling cooling method. It relates to the technical field of drilling engineering. The device comprises: an ice making bin, which is cooled to a preset low temperature threshold by liquid nitrogen atomization, and then atomizes liquid water, so that the water mist and the low-temperature nitrogen gas contact and phase change to form ice particles. A gas transmission pipeline is connected to the gas outlet of the ice making bin, and the low-temperature nitrogen gas is sent to the heat exchanger and the outer layer of the drilling fluid injection pipeline respectively. The heat exchanger exchanges heat with the high-temperature drilling fluid returned from the bottom of the well, so that the pre-cooling and cooling are realized. The outer layer of the drilling fluid injection pipeline uses the low-temperature nitrogen gas to keep the drilling fluid to be injected into the well warm. The mud tank is connected to the ice particle outlet of the ice making bin and the pre-cooled drilling fluid outlet of the heat exchanger at the same time, the ice particles and the pre-cooled drilling fluid are mixed to form ice crystal drilling fluid, and the ice crystal drilling fluid is transported to the drilling fluid injection pipeline. The ice crystal drilling fluid is pumped into the well by the drilling pump through the drilling fluid injection pipeline.

Description

Technical Field

[0001] This invention relates to the field of drilling engineering technology, and in particular to a drilling cooling device and a drilling cooling method. Background Technology

[0002] As deep oil and gas exploration and development advances to ultra-deep wells reaching depths of tens of thousands of meters, the performance stability of drilling fluids in high-temperature wellbore environments has become a key bottleneck restricting drilling efficiency and wellbore safety. Bottom-hole circulation temperatures can reach over 180°C. High temperatures can lead to the destruction of drilling fluid colloidal stability, failure of filtration reducers, lubricant carbonization, and accelerated equipment corrosion. They also cause derivative problems such as additive precipitation and formation gas escape foaming, significantly increasing the risk of stuck pipe and drill bit failure. Therefore, achieving efficient temperature control of drilling fluids throughout the entire process from the surface to the bottom of the well is a crucial technical challenge that urgently needs to be overcome in ultra-deep well drilling.

[0003] Existing technologies typically establish a direct contact or indirect conduction loop between the external cold source and the high-temperature drilling fluid by increasing the heat exchanger area or increasing the flow rate of the cooling medium, thereby continuously increasing the supply of cooling capacity to offset the heat load at the bottom of the well and thus maintaining the temperature of the drilling fluid within a preset range before it enters the well.

[0004] However, due to the heat exchange limitations during long-distance transport, the liquid refrigerant absorbs heat from the environment and returning liquids along the way, causing the temperature to rise. This results in a significant amount of cooling energy being dissipated before reaching the bottom of the well. Simply increasing the surface cooling supply is insufficient to achieve targeted cooling of deep wells. If the refrigerant injection volume is significantly increased to compensate for heat loss along the way, the temperature of the surface transport pipeline and heat exchange equipment can easily drop below freezing, causing the drilling fluid to freeze or the pipeline to become blocked, leading to the paralysis of the circulation system. This contradiction between the demand for deep well cooling and the safety of surface equipment transport makes it impossible to achieve efficient deep well cooling while ensuring the safe operation of the system. Summary of the Invention

[0005] Therefore, it is necessary to provide a drilling cooling device and a drilling cooling method to address the aforementioned technical problems.

[0006] The following technical solution is adopted in this specification: This manual provides a drilling cooling device, including: An ice-making chamber is used to reduce the internal temperature of the ice-making chamber to a preset low temperature threshold by liquid nitrogen atomization, and after the low temperature threshold is reached, the stored liquid water is atomized, so that the water mist comes into contact with low temperature nitrogen gas and undergoes a phase change to condense and generate ice particles. A gas transmission pipeline is connected to the atomized liquid nitrogen gas outlet of the ice-making chamber, and is used to transport the low-temperature nitrogen gas discharged during the ice-making process to the heat exchanger and the outer layer of the drilling fluid injection pipeline, respectively. The heat exchanger is used to exchange heat with the high-temperature drilling fluid returning from the bottom of the well, so as to pre-cool the high-temperature drilling fluid. The outer layer of the drilling fluid injection pipe is set outside the drilling fluid injection pipe and is used to keep the drilling fluid to be pumped into the well in the drilling fluid injection pipe warm using the low temperature nitrogen gas. The mud tank is connected to both the ice particle outlet of the ice-making chamber and the pre-cooled drilling fluid outlet of the heat exchanger. It is used to mix the ice particles with the pre-cooled high-temperature drilling fluid to form ice crystal drilling fluid, and to transport the ice crystal drilling fluid to the drilling fluid injection pipeline. A drilling pump, connected to the drilling fluid injection pipeline, is used to pump the ice crystal drilling fluid into the well.

[0007] Furthermore, the ice-making chamber is an insulated container, consisting of an upper cylindrical body and a lower inverted conical body that are sealed together. The sidewall of the cylindrical body is provided with liquid nitrogen atomizing devices along the circumferential or axial direction, and the top wall of the cylindrical body is provided with liquid water atomizing devices. The spray direction of the liquid nitrogen atomizing devices and the liquid water atomizing devices is towards the internal space of the ice-making chamber, and the spray flow fields of the two converge in the ice-making chamber so that the water mist and the low temperature nitrogen gas can fully contact each other and undergo phase change condensation to generate ice particles. The bottom end of the inverted conical cylinder is provided with the ice particle outlet.

[0008] Furthermore, a valve assembly for controlling the ice particle discharge rate is provided at the ice particle outlet.

[0009] Furthermore, it also includes a temperature monitoring and feedback control module, which includes: A temperature sensor is installed at least at one of the ice-making chamber, the mud tank, and the drilling fluid injection pipeline; The data processing unit is connected to the temperature sensor signal; The data processing unit adjusts at least one of the following based on the temperature signal collected by the temperature sensor: the liquid nitrogen injection rate of the liquid nitrogen atomizing device, the water atomization rate of the liquid water atomizing device, and the opening degree of the valve assembly. This is done by adjusting the ice-making rate and the ice particle discharge rate to control the temperature of the ice crystal drilling fluid.

[0010] Furthermore, the gas transmission pipeline is provided with branch lines, one of which is connected to the heat exchanger, and the other is connected to the outer layer of the drilling fluid injection pipeline; A flow regulating valve is installed at the interface of the branch circuit to regulate the flow rate of low-temperature nitrogen entering the heat exchanger and the outer layer of the drilling fluid injection pipeline, so as to match the heat exchange and insulation requirements under different operating conditions.

[0011] Furthermore, the heat exchanger is a spiral heat exchanger. The low-temperature nitrogen gas is introduced into the tube side flow channel of the spiral heat exchanger. The high-temperature drilling fluid returning from the bottom of the well flows in the shell side of the spiral heat exchanger. The low-temperature nitrogen gas in the tube side and the high-temperature drilling fluid in the shell side flow in opposite directions and exchange heat to achieve pre-cooling of the high-temperature drilling fluid.

[0012] Furthermore, the outer layer of the drilling fluid injection pipe is an insulating sleeve fitted outside the drilling fluid injection pipe, and an annular jacket space is formed between the insulating sleeve and the outer wall of the drilling fluid injection pipe. The low-temperature nitrogen gas circulates within the annular jacket space to maintain the low-temperature state of the drilling fluid inside the drilling fluid injection pipe.

[0013] Furthermore, the mud tank is equipped with a treatment agent addition port and a stirring device; The treatment agent addition port is used to add density regulator, viscosity regulator and water loss wall-building regulator to the pre-cooled drilling fluid. The stirring device is used to stir and mix the ice particles, the pre-cooled drilling fluid, and the treatment agent to form an ice crystal drilling fluid with uniform ice particle distribution and stable performance.

[0014] Furthermore, the ice particles generated in the ice-making chamber are spherical or near-spherical low-temperature ice particles, and the temperature of the ice particles is below -80°C; The temperature of the drilling fluid in the mud tank after pre-cooling is controlled in the range of 0~5℃. The ice particles are mixed with the pre-cooled drilling fluid to form a uniformly suspended ice crystal drilling fluid.

[0015] This manual provides a drilling cooling method, including: After the temperature inside the ice-making chamber is lowered to a set low temperature threshold by liquid nitrogen atomization, liquid water is atomized. The water mist comes into contact with the low temperature nitrogen gas and undergoes a phase change to condense and generate ice particles. The ice particles fall into the mud tank below by gravity. The low-temperature nitrogen gas discharged during the ice-making process is introduced into the spiral heat exchanger and the outer layer of the drilling fluid transmission pipeline. The low-temperature nitrogen gas exchanges heat with the high-temperature drilling fluid returning from the bottom of the well in the spiral heat exchanger, pre-cooling the high-temperature drilling fluid returning from the bottom of the well. The low-temperature nitrogen gas circulates in the outer layer of the drilling fluid transmission pipeline to keep the drilling fluid to be pumped into the well in the pipeline warm. Ice particles are mixed with pre-cooled drilling fluid in the mud tank to form ice crystal drilling fluid, which is then pumped into the well by a drilling pump. As the ice particles circulate along the wellbore with the drilling fluid, they absorb heat and undergo a phase change to melt, thus controlling the wellbore temperature.

[0016] The above-mentioned technical solutions adopted in this specification can achieve the following beneficial effects: This invention introduces low-temperature nitrogen gas discharged from the ice-making chamber into the heat exchanger and the outer layer of the drilling fluid injection pipe via a gas transmission pipeline. The cold energy of the waste gas is used to pre-cool the returning high-temperature drilling fluid and insulate the drilling fluid to be injected. Because the low-temperature nitrogen gas absorbs heat from the returning fluid in advance in the heat exchanger, the base temperature of the drilling fluid circulation is reduced. Furthermore, a low-temperature insulation layer is constructed on the outer layer of the injection pipe to block the intrusion of external heat sources. This significantly reduces the loss of cooling capacity during surface transportation without increasing external energy consumption, avoiding the problem of insufficient cooling at the well bottom due to heat absorption along the way by liquid refrigerant. Moreover, the ice particles are transported in solid form with the drilling fluid to the high-temperature zone at the bottom of the well, releasing latent heat through a solid-liquid phase change, directly carrying the cooling capacity to the target temperature zone. Combined with the nitrogen insulation mechanism on the outer layer of the injection pipe, this prevents the ice particles from melting prematurely, avoiding the cooling capacity attenuation caused by heat absorption along the way in traditional liquid refrigerant transportation over long distances. This achieves targeted cooling of deep wells, resulting in a dual improvement in cooling depth and operational stability. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 This is a schematic diagram of a drilling cooling device provided in this specification; Figure 2 This is a schematic diagram of a drilling cooling method provided in this specification; 1-Ice making chamber; 2-Gas transmission pipeline; 3-Heat exchanger; 4-Outer layer of drilling fluid injection pipeline; 5-Drilling fluid injection pipeline; 6-Mud tank; 7-Drilling pump; 8-Temperature monitoring and feedback control module; 101-Liquid nitrogen atomization device; 102-Liquid water atomization device; 103-Ice particle outlet; 104-Valve assembly; 601-Treatment agent addition port; 602-Stirring device; 801-Temperature sensor; 802-Data processing unit. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this specification clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this specification without creative effort are within the scope of protection of this application.

[0020] The technical solution provided by this invention is mainly applied to ultra-deep well (especially 10,000-meter-class deep well) operation scenarios. With the advancement of deep oil and gas resource exploration and development, drilling in 10,000-meter-class ultra-deep wells faces the problems of high wellbore temperature and surface heat loss, seriously threatening the stability of drilling fluid performance. Specifically, high temperature first damages the colloidal stability of the drilling fluid: above 180℃, clay particles flocculate, and viscosity increases sharply by 300%-500%, leading to increased energy consumption and decreased circulation efficiency; above 200℃, clay degrades, losing its rock-carrying capacity and easily causing stuck drill bit. High temperature also causes the failure of filtration reduction agents: above 160℃, molecular chains break, filtration loss surges, leading to risks such as well leakage, wellbore collapse, and well kick. Simultaneously, high temperature causes lubricants, corrosion inhibitors, and bactericides to become ineffective, exacerbating equipment wear and corrosion; the large temperature difference between the well and the surface causes additive precipitation and increased foaming, further damaging drilling fluid performance and accelerating drill bit failure. To address the aforementioned issues, existing drilling fluid types all have significant shortcomings: water-based drilling fluids are difficult to cool effectively, while oil-based drilling fluids cause considerable pollution. While liquid nitrogen cooling shows potential, direct injection into the wellbore presents drawbacks such as high cost, difficulty in temperature control, and susceptibility to icing. Therefore, ultra-deep well drilling urgently requires a solution capable of effectively controlling the temperature from the wellhead to a depth of 100 meters.

[0021] Based on this, this application proposes a drilling cooling device. The core idea is to achieve the preparation and pumping of surface ice crystal drilling fluid through multi-stage cooling of the drilling fluid and efficient preparation of ice particles. This results in drilling fluid containing ice particles of uniform size, which are then transported to the well depth of 10,000 meters via insulated drill pipe. The phase change of the ice particles absorbs heat, reducing the drill bit temperature and thus protecting the downhole drilling equipment. The device mainly consists of four parts: an ice-making chamber, a multi-stage pre-cooling system, an online monitoring and feedback control system, and existing drilling fluid circulation equipment. The ice-making chamber employs liquid nitrogen-water dual atomization ice-making technology. Liquid nitrogen and trace amounts of water are instantaneously atomized within a sealed chamber through dual nozzles, forming highly spherical ice particles with a temperature below -80℃. The cold nitrogen gas generated during vaporization is then exported as a cold source, improving the utilization efficiency of liquid nitrogen. The multi-stage precooling system includes primary precooling, secondary precooling, and tertiary insulation: Primary precooling involves installing a spiral coil heat exchanger before the mud tank to cool the high-temperature drilling fluid returning from the bottom of the well; secondary precooling utilizes ice-making equipment above the mud tank to rapidly cool the drilling fluid, ultimately reducing its temperature to 0-5°C, eliminating the risk of freezing; tertiary insulation guides the low-temperature nitrogen gas discharged during ice-making to the outer layer of the drilling fluid transmission pipeline, ensuring that the drilling fluid does not heat up before being pumped underground. The online monitoring and feedback control system installs sensors for temperature and ice crystal concentration before the pump to achieve online detection of the drilling fluid's rheological properties. The control system adjusts the liquid nitrogen injection rate and ice particle dosing rate to ensure the drilling fluid temperature remains stable within the set range. In addition, existing drilling fluid circulation equipment serves as the basic supporting component of this device, including purification equipment such as vibrating screens, desanders, and desilters, storage equipment such as mud tanks and mixing tanks, and flow and power equipment such as drill pipes, drill bits, and drilling pumps. This device can be directly embedded into the existing circulation process and work in conjunction with the above-mentioned equipment to achieve the preparation, circulation, and temperature control of ice crystal drilling fluid.

[0022] The drilling cooling device of the present invention will now be described with reference to the accompanying drawings.

[0023] Figure 1 This is a structural schematic diagram of a drilling cooling device provided in this specification, such as... Figure 1 As shown, the device includes: Ice-making chamber 1 is used to lower its internal temperature to a preset low-temperature threshold through liquid nitrogen atomization. After reaching this threshold, it atomizes the stored liquid water, causing the water mist to condense into ice particles upon contact with the low-temperature nitrogen gas, resulting in a phase change. Ice-making chamber 1 is an insulated container, entirely made of stainless steel and externally covered with insulation material. It consists of an upper cylindrical body and a lower inverted conical body that are sealed together. The side walls of the cylindrical body are equipped with liquid nitrogen atomizing devices 101 arranged circumferentially or axially. The liquid nitrogen pipelines are arranged in a convection pattern, with multiple liquid nitrogen nozzles connected in series on each pipeline to spray liquid nitrogen in a mist form. The top wall of the cylindrical body is equipped with a liquid water atomizing device 102, which uses a lifting water atomizing nozzle to break the liquid water into fine droplets. The liquid nitrogen atomizing device 101 and the liquid water atomizing device 102 spray towards the interior space of the ice-making chamber 1, and their spray flow fields converge within the ice-making chamber 1, so that the water mist and low-temperature nitrogen gas can fully contact each other and undergo phase change condensation to generate spherical or near-spherical ice particles with a temperature below -80℃. An ice particle outlet 103 is provided at the bottom end of the inverted conical cylinder, and a valve assembly 104 is provided at the ice particle outlet 103 to control the ice particle discharge rate, adjusting the ice discharge rate by controlling the opening degree.

[0024] The ice pellet preparation principle is dual atomization ice making. Atomized water droplets from the water atomizing nozzle come into contact with atomized liquid nitrogen from the liquid nitrogen nozzle, rapidly cooling and causing a phase change to form ice pellets. After being generated in the ice-making chamber 1, the ice pellets fall under gravity to the ice pellet outlet 103 at the head of the lower inverted cone-shaped cylinder, and then fall into the lower mud tank 6 via valve assembly 104. When the ice pellets mix with the drilling fluid in the mud tank 6, they absorb heat and undergo a phase change from solid to liquid. No other substances are generated during this process, therefore it does not affect the composition of the drilling fluid. The low-temperature nitrogen gas generated in the ice-making chamber 1 is drawn out through the gas transmission pipe 2 at a temperature of approximately -70°C.

[0025] Gas transmission pipeline 2, connected to the atomized liquid nitrogen gas outlet of ice-making chamber 1, is used to transport the low-temperature nitrogen gas discharged during the ice-making process to heat exchanger 3 and the outer layer 4 of drilling fluid injection pipeline. Gas transmission pipeline 2 has branch lines, one of which connects to heat exchanger 3, and the other connects to the outer layer 4 of drilling fluid injection pipeline. Flow regulating valves are installed at the interfaces of each branch line to regulate the flow rate of low-temperature nitrogen gas entering heat exchanger 3 and the outer layer 4 of drilling fluid injection pipeline, so as to match the heat exchange and insulation requirements under different operating conditions. The pipeline is designed to withstand low temperatures, and the low-temperature nitrogen gas is discharged in an orderly manner after circulation, preventing pressure buildup during system operation.

[0026] Heat exchanger 3 is used to exchange heat with the high-temperature drilling fluid returning from the bottom of the well, thereby pre-cooling the high-temperature drilling fluid. In this embodiment, heat exchanger 3 is a spiral heat exchanger. Low-temperature nitrogen gas is introduced into the tube side of the spiral heat exchanger, and the high-temperature drilling fluid returning from the bottom of the well flows in the shell side of the spiral heat exchanger. The low-temperature nitrogen gas in the tube side flows counterclockwise with the high-temperature drilling fluid in the shell side and exchanges heat, achieving primary pre-cooling of the high-temperature drilling fluid. The heat exchanger body and coils have low-temperature resistance and reliable sealing performance, and the low-temperature nitrogen gas is discharged in an orderly manner after heat exchange through the coils.

[0027] The outer layer 4 of the drilling fluid injection pipeline, located outside the drilling fluid injection pipeline 5, is used to insulate the drilling fluid to be pumped into the well using cryogenic nitrogen gas. The outer layer 4 is an insulating sleeve fitted over the drilling fluid injection pipeline 5, forming an annular jacket space between the insulating sleeve and the outer wall of the drilling fluid injection pipeline 5. Cryogenic nitrogen gas circulates within this annular jacket space to maintain the cryogenic state of the drilling fluid inside the drilling fluid injection pipeline 5. The transmission pipeline adopts a double-layer insulation structure design. The insulation layer effectively blocks heat exchange between the inside and outside of the pipeline, minimizing heat loss of the drilling fluid during transportation, ensuring that ice particles do not absorb heat from the outside and melt during transport, and adequately cooling the drilling fluid.

[0028] The mud tank 6 is connected to both the ice particle outlet 103 of the ice-making chamber 1 and the pre-cooled drilling fluid outlet of the heat exchanger 3. It is used to mix ice particles with the pre-cooled, high-temperature drilling fluid to form ice crystal drilling fluid, and then transport the ice crystal drilling fluid to the drilling fluid injection pipe 5. The mud tank 6 is also equipped with a treatment agent addition port 601 and a stirring device 602. The treatment agent addition port 601 is used to add density regulators, viscosity regulators, and water loss wall-building regulators to the pre-cooled drilling fluid for final performance adjustments before pumping it underground. The stirring device 602 is used to mix the ice particles, the pre-cooled drilling fluid, and the treatment agents to form a uniformly distributed, stable ice crystal drilling fluid. After the fully cooled drilling fluid and ice particles are mixed before pumping, the drilling fluid temperature can be controlled within the range of 0~5℃, within which there is no risk of freezing.

[0029] The drilling pump 7 is connected to the drilling fluid injection pipe 5 and is used to pump ice crystal drilling fluid into the well through the drilling fluid injection pipe 5.

[0030] The device also includes a temperature monitoring and feedback control module 8, which consists of a temperature sensor 801 installed at least once in the ice-making chamber 1, the mud tank 6, and the drilling fluid injection pipe 5, and a data processing unit 802 connected to the temperature sensor 801. Specifically, the temperature sensor 801 includes a temperature probe and a temperature data processing device, which are respectively arranged in the ice-making structure of the ice-making chamber 1, near the valve assembly 104 at the ice particle outlet 103, inside the mud tank 6, and inside the drilling fluid injection pipe 5, and can monitor the temperature of each part in real time. The data acquisition device provides real-time feedback on the temperature changes of each part based on the acquired temperature signals. The data processing unit 802, based on the temperature signals acquired by the temperature sensor 801, provides feedback to adjust at least one of the following: the liquid nitrogen injection rate of the liquid nitrogen atomizing device 101, the water atomization rate of the liquid water atomizing device 102, and the opening degree of the valve assembly 104, in order to control the temperature of the ice crystal drilling fluid.

[0031] This device requires minimal modification to the existing drilling fluid transport structure and works in conjunction with existing drilling fluid circulation equipment. Existing circulation equipment includes purification devices such as vibrating screens, desanders, and desilters; storage devices such as mud tanks and mixing tanks; and downhole flow and power equipment such as drill pipes, drill bits, and drilling pumps. Drilling fluid returning from the bottom of the well first passes through the vibrating screen, desander, and desilter to remove cuttings and impurities. It then enters the spiral heat exchanger 3 for primary pre-cooling, before flowing into the mud tank 6 to mix with ice particles. Finally, the insulated drilling fluid is pumped into the well by the drilling pump 7 through the injection pipeline 5. Ice particles do not enter the multi-stage pre-cooling equipment, fundamentally and effectively avoiding risks such as heat exchanger icing, pipeline freezing, and abnormal pump suction, thus improving the system's operational stability and continuous cycle performance.

[0032] The system workflow is as follows: First, the liquid nitrogen truck releases liquid nitrogen into the ice-making chamber 1. The liquid nitrogen is then atomized by the liquid nitrogen atomizing device 101, lowering the temperature inside the chamber to approximately -140°C. Once the preset temperature is reached, the liquid water atomizing device 102 is activated to break the liquid water into droplets. The water droplets come into contact with the low-temperature nitrogen gas, undergoing a phase change to generate spherical ice particles with a temperature below -80°C. These ice particles fall to the bottom of the cone under gravity and then through the valve assembly 103 into the mud tank 6. Simultaneously, the low-temperature nitrogen gas generated during the ice-making process, at approximately -70°C, is split through the gas transmission pipeline 2. One path is introduced into the spiral heat exchanger 3, and the other path is introduced into the annular jacket space of the drilling fluid injection pipeline 4.

[0033] The high-temperature drilling fluid returning to the surface from the bottom of the well first enters solids control equipment (such as vibrating screens, desanders, desilters, etc.) for purification to remove rock cuttings and impurities. Subsequently, the purified drilling fluid enters spiral heat exchanger 3, where it undergoes counter-current heat exchange with low-temperature nitrogen gas in the tube side, achieving primary pre-cooling.

[0034] The pre-cooled drilling fluid flows into mud tank 6 and mixes with the falling ice particles. Operators add density and viscosity modifiers through the additive inlet 601, and the mixture is stirred evenly by the agitator 602 to form a uniform suspension of ice crystals in the drilling fluid. A temperature sensor monitors the tank temperature in real time, and the feedback control system adjusts the opening of valve assembly 103 to control the ice particle addition rate, precisely controlling the drilling fluid temperature in mud tank 6 within the range of 0~5℃.

[0035] Drilling pump 7 starts, pumping the ice crystal drilling fluid in mud tank 6 into the well via drilling fluid injection pipe 5. During the transportation process, low-temperature nitrogen circulating in the outer layer 4 of the drilling fluid injection pipe is used for insulation to prevent the ice particles from melting prematurely and to maintain the low temperature of the drilling fluid.

[0036] The ice-crystal drilling fluid flows through the downhole equipment to the drill bit. The cryogenic fluid directly cools the drill bit and lubricates the drill string, reducing drilling torque and wear. The drilling fluid then carries rock cuttings back to the surface along the annulus. During this process, the ice particles absorb formation heat and undergo a phase change as they circulate along the wellbore, releasing latent heat of phase change (approximately 330 kJ / kg), thus effectively controlling the wellbore temperature rise. The drilling fluid returning to the surface re-enters the solids control equipment and heat exchanger, forming a closed-loop circulation. During this circulation, the cryogenic drilling fluid more easily forms a high-quality mud cake on the wellbore, stabilizing the wellbore and preventing collapse.

[0037] This invention employs a "pre-cooling, then ice injection" process to precisely locate the temperature control point, concentrating the cooling energy on the wellhead to the 100-meter well section. This fundamentally prevents premature melting of ice particles during the pre-cooling stage, effectively solving the industry pain point of large surface cold energy absorption in deep wells. The system uses a liquid nitrogen-water dual atomization process to produce uniformly sized ice particles at a temperature maintained at -80℃. The mixture of liquid and water allows for slow melting, releasing a latent heat of phase change of up to 330 kJ / kg, achieving a dual improvement in both rapid, large-scale cooling and sustained, slow-release cooling. Furthermore, the system innovates a multi-stage cold energy recovery mechanism, converting the cold nitrogen generated during ice production into a cold source for the pre-cooling system. Combined with a stepped temperature drop, the entire process of closed-loop cooling and heating significantly improves the efficiency of liquid nitrogen cold energy utilization and reduces consumption costs. By optimizing the process, ice particles are prevented from entering the multi-stage pre-cooling equipment, and precise quantitative addition is achieved near the wellhead using a valve-type device. This fundamentally avoids risks such as heat exchanger icing, pipe freezing, and abnormal pump suction, improving the system's operational stability and continuous cycle performance. The system is also equipped with a temperature detection module, enabling rapid monitoring and early warning systems to build a real-time feedback and adjustment system. Furthermore, the core unit can be deployed in a containerized manner, possessing the potential for large-scale engineering application. The entire technology uses liquid nitrogen as its core, without the participation of any chemical additives. The evaporation of liquid nitrogen only produces pure nitrogen gas without any waste gas emissions, providing reliable technical support for the transformation of deep wells towards a green, low-carbon, and intelligent approach.

[0038] The drilling cooling method provided by the present invention is described below. The drilling cooling method described below can be referred to in correspondence with the drilling cooling device described above.

[0039] Figure 2 This is a flowchart illustrating a drilling cooling method provided in this specification. For example, please refer to [link to flowchart illustration]. Figure 2 As shown, the drilling cooling method may include: Inside the ice-making chamber, the temperature is lowered to a set low-temperature threshold by liquid nitrogen atomization. Then, liquid water is atomized, and the water mist comes into contact with the low-temperature nitrogen gas, causing a phase change and condensation to form ice particles. The ice particles fall into the mud tank below under the influence of gravity.

[0040] The low-temperature nitrogen gas discharged during the ice-making process is introduced into the spiral heat exchanger and the outer layer of the drilling fluid transmission pipeline. The low-temperature nitrogen gas exchanges heat with the high-temperature drilling fluid returning from the bottom of the well in the spiral heat exchanger, pre-cooling the high-temperature drilling fluid returning from the bottom of the well. The low-temperature nitrogen gas circulates in the outer layer of the drilling fluid transmission pipeline to keep the drilling fluid to be pumped into the well in the pipeline warm.

[0041] Ice particles are mixed with pre-cooled drilling fluid in the mud tank to form ice crystal drilling fluid, which is then pumped into the well by a drilling pump. As the ice particles circulate along the wellbore with the drilling fluid, they absorb heat and undergo a phase change to melt, thus controlling the wellbore temperature.

[0042] For specific limitations on drilling cooling methods, please refer to the limitations on drilling cooling devices mentioned above, which will not be repeated here.

[0043] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A drilling cooling device, characterized in that, include: Ice-making chamber (1) is used to reduce the internal temperature of the ice-making chamber (1) to a preset low temperature threshold by liquid nitrogen atomization, and after reaching the low temperature threshold, liquid water is atomized so that the water mist comes into contact with low temperature nitrogen and undergoes phase change condensation to generate ice particles. The gas transmission pipeline (2) is connected to the atomized liquid nitrogen gas outlet of the ice-making chamber (1) and is used to transport the low-temperature nitrogen gas discharged during the ice-making process to the heat exchanger (3) and the outer layer (4) of the drilling fluid injection pipeline respectively. The heat exchanger (3) is used to exchange heat with the high-temperature drilling fluid returning from the bottom of the well to pre-cool the high-temperature drilling fluid. The outer layer (4) of the drilling fluid injection pipe is set outside the drilling fluid injection pipe (5) and is used to keep the drilling fluid to be pumped into the well in the drilling fluid injection pipe (5) warm by using the low temperature nitrogen gas. The mud tank (6) is connected to the ice particle outlet of the ice making chamber (1) and the pre-cooled drilling fluid outlet of the heat exchanger (3) at the same time. It is used to mix the ice particles with the pre-cooled high-temperature drilling fluid to form ice crystal drilling fluid, and to transport the ice crystal drilling fluid to the drilling fluid injection pipe (5). A drilling pump (7) is connected to the drilling fluid injection pipe (5) and is used to pump the ice crystal drilling fluid into the well.

2. The drilling cooling device according to claim 1, characterized in that, The ice-making chamber (1) is an insulated container, which is formed by a sealed connection between the upper cylindrical body and the lower inverted conical body; The sidewall of the cylindrical body is provided with a liquid nitrogen atomizing device (101) along the circumferential or axial direction, and the top wall of the cylindrical body is provided with a liquid water atomizing device (102). The spray direction of the liquid nitrogen atomizing device (101) and the liquid water atomizing device (102) is towards the internal space of the ice-making chamber (1), and the spray flow fields of the two converge in the ice-making chamber (1) so that the water mist and the low temperature nitrogen gas can fully contact each other and undergo phase change condensation to generate ice particles. The bottom end of the inverted conical cylinder is provided with the ice particle outlet (103).

3. The drilling cooling device according to claim 2, characterized in that, A valve assembly (104) for controlling the ice discharge rate is provided at the ice particle outlet (103).

4. The drilling cooling device according to claim 3, characterized in that, It also includes a temperature monitoring and feedback control module (8), which includes: Temperature sensors (801) are installed at least at one of the ice-making chamber (1), the mud tank (6), and the drilling fluid injection pipeline (5); A data processing unit (802) connected to the temperature sensor (801) for signal processing; The data processing unit (802) adjusts at least one of the following based on the temperature signal collected by the temperature sensor (801): the liquid nitrogen injection rate of the liquid nitrogen atomizing device (101), the water atomization rate of the liquid water atomizing device (102), and the opening degree of the valve assembly (104), so as to control the temperature of the ice crystal drilling fluid by adjusting the ice-making rate and the ice particle discharge rate.

5. The drilling cooling device according to claim 1, characterized in that, The gas transmission pipeline (2) is provided with branch lines, one of which is connected to the heat exchanger (3), and the other branch is connected to the outer layer (4) of the drilling fluid injection pipeline. A flow regulating valve is provided at the interface of the branch circuit to regulate the flow rate of low-temperature nitrogen entering the heat exchanger (3) and the outer layer (4) of the drilling fluid injection pipeline, so as to match the heat exchange and insulation requirements under different working conditions.

6. The drilling cooling device according to claim 1, characterized in that, The heat exchanger (3) is a spiral heat exchanger. The low-temperature nitrogen gas is introduced into the tube side flow channel of the spiral heat exchanger. The high-temperature drilling fluid returning from the bottom of the well flows in the shell side of the spiral heat exchanger. The low-temperature nitrogen gas in the tube side and the high-temperature drilling fluid in the shell side flow in opposite directions and exchange heat to achieve pre-cooling of the high-temperature drilling fluid.

7. The drilling cooling device according to claim 1, characterized in that, The outer layer (4) of the drilling fluid injection pipe is an insulating sleeve fitted outside the drilling fluid injection pipe (5). An annular jacket space is formed between the insulating sleeve and the outer wall of the drilling fluid injection pipe (5). The low-temperature nitrogen gas circulates in the annular jacket space to maintain the low temperature state of the drilling fluid in the drilling fluid injection pipe (5).

8. The drilling cooling device according to claim 1, characterized in that, The mud tank (6) is equipped with a treatment agent addition port (601) and a stirring device (602); The treatment agent addition port (601) is used to add density regulator, viscosity regulator and water loss wall-building regulator to the pre-cooled drilling fluid; The stirring device (602) is used to stir and mix the ice particles, the pre-cooled drilling fluid, and the treatment agent to form an ice crystal drilling fluid with uniform ice particle distribution and stable performance.

9. The drilling cooling device according to claim 1, characterized in that, The ice particles generated in the ice-making chamber (1) are spherical or near-spherical low-temperature ice particles, and the temperature of the ice particles is below -80°C; The temperature of the drilling fluid in the mud tank (6) after pre-cooling is controlled in the range of 0~5℃. The ice particles are mixed with the pre-cooled drilling fluid to form a uniformly suspended ice crystal drilling fluid.

10. A drilling cooling method for the drilling cooling device according to claims 1-9, characterized in that, include: After the temperature inside the ice-making chamber is lowered to a set low temperature threshold by liquid nitrogen atomization, liquid water is atomized. The water mist comes into contact with the low temperature nitrogen gas and undergoes a phase change to condense and generate ice particles. The ice particles fall into the mud tank below by gravity. The low-temperature nitrogen gas discharged during the ice-making process is introduced into the spiral heat exchanger and the outer layer of the drilling fluid transmission pipeline. The low-temperature nitrogen gas exchanges heat with the high-temperature drilling fluid returning from the bottom of the well in the spiral heat exchanger, pre-cooling the high-temperature drilling fluid returning from the bottom of the well. The low-temperature nitrogen gas circulates in the outer layer of the drilling fluid transmission pipeline to keep the drilling fluid to be pumped into the well in the pipeline warm. Ice particles are mixed with pre-cooled drilling fluid in the mud tank to form ice crystal drilling fluid, which is then pumped into the well by a drilling pump. As the ice particles circulate along the wellbore with the drilling fluid, they absorb heat and undergo a phase change to melt, thus controlling the wellbore temperature.

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