Cooling control method, drilling system and program product

Abstract

The invention provides a cooling control method, a drilling system and a program product. The well drilling system comprises a ground drilling fluid cooling subsystem used for conducting graded cooling on drilling fluid returned from a shaft by a drilling fluid conveying pipeline based on cooling parameters and re-injecting the cooled drilling fluid into the drilling fluid conveying pipeline located in the shaft; the underground drill column is provided with at least one heat shielding drill rod used for reducing heat transferred to the interior of the drill column from the high-temperature annulus. The control subsystem is used for obtaining the shaft temperature distribution condition in the drilling fluid circulation process according to the shaft thermodynamic model, and controlling the cooling parameters of the drilling fluid cooling subsystem and the tripping-in time and position of the heat shielding drill rod based on the shaft temperature distribution condition in the drilling fluid circulation process; the underground while-drilling instrument is provided with a heat dredging device and used for reducing the heat conduction amount of the external environment to the underground while-drilling instrument. According to the invention, conventional drilling technical equipment can be suitable for the shaft temperature environment of drilling of an ultra-deep well and a geothermal well.

Description

Technical Field

[0001] The present application relates to the field of drilling, and in particular to a temperature reduction control method, a drilling system and a program product. Background Art

[0002] With the increase in energy demand and the development of oil drilling technology, the exploration and development of oil and gas resources has continued to deepen. The formation temperature increases with depth. For ultra-deep wells and high-temperature geothermal well drilling operations, the wellbore operating environment temperature is getting higher and higher.

[0003] As for the problem of ultra-high temperature in the underground environment during drilling, the main means of cooling the wellbore is to bring the heat to the ground through the circulation of drilling fluid, and then use large-scale cooling equipment on the ground to cool the drilling fluid and re-inject the cooled drilling fluid into the wellbore. However, as the drilling depth continues to increase, the underground temperature continues to rise. The current ground cooling and heat exchange equipment has low cooling efficiency and poor insulation performance of the underground pipe string. The existing full-well temperature control system cannot meet the current needs of ultra-high temperature well drilling. Summary of the invention

[0004] The present application provides a temperature reduction control method, a drilling system and a program product to solve the problem that the existing full-well temperature control system cannot meet the current requirements of ultra-high temperature well drilling.

[0005] In a first aspect, an embodiment of the present application provides a drilling system, the system comprising: a control subsystem, a ground drilling fluid cooling subsystem, a drilling fluid delivery pipeline, a downhole drill string, and a downhole drilling instrument;

[0006] The surface drilling fluid cooling subsystem includes a plurality of cascaded cooling devices, which are used to perform graded cooling on the drilling fluid returned from the wellbore through the drilling fluid delivery pipeline based on the cooling parameters, and to re-inject the cooled drilling fluid into the drilling fluid delivery pipeline located in the wellbore;

[0007] The downhole drill string is equipped with at least one heat shield drill rod, which is used to reduce the heat transferred from the high-temperature annulus to the inside of the drill string; the installation position of the heat shield drill rod is related to the temperature distribution of the wellbore;

[0008] The control subsystem is used to obtain the wellbore temperature distribution during the drilling fluid circulation process according to the wellbore thermodynamic model, and control the cooling parameters of the drilling fluid cooling subsystem and the lowering time and position of the heat shield drill rod based on the wellbore temperature distribution during the drilling fluid circulation process;

[0009] The downhole drilling instrument is equipped with a heat conduction device for reducing the amount of heat conducted by the external environment to the downhole drilling instrument.

[0010] In some embodiments, the surface drilling fluid cooling subsystem is also used to recover the heat released during the drilling fluid cooling process.

[0011] In some embodiments, the surface drilling fluid cooling subsystem is further used for:

[0012] Detecting the performance parameters of the cooled drilling fluid and outputting the performance test results; the performance parameters include: density, viscosity and temperature of the drilling fluid;

[0013] Determine whether to re-inject the cooled drilling fluid into the wellbore according to the performance test result.

[0014] In some embodiments, the heat shielding drill pipe type includes: a drill pipe filled with a heat insulating material, or a drill pipe with a thermal barrier coating sprayed on the inner and outer walls.

[0015] In some embodiments, the heat conduction device is a heat conducting plate;

[0016] The heat conducting plates are respectively connected to the components of the circuit compartment and the circuit compartment wall of the while drilling instrument.

[0017] In some embodiments, the inner wall of the circuit compartment of the while drilling instrument is sprayed with a thermal barrier coating.

[0018] In some embodiments, a cold source with an active cooling function is installed in the circuit compartment of the drilling instrument.

[0019] In some embodiments, phase change endothermic material is added to the drilling fluid.

[0020] In some embodiments, the control subsystem is specifically used to:

[0021] According to the drilling depth, the number of axial grids and radial grids of the wellbore are obtained, wherein the number of radial target position grids is greater than the number of bottom position grids; the target position includes at least one of the following: water eye, drill string, annulus and well wall;

[0022] According to the number of axial grids and radial grids, a second-order upwind format and a fully implicit time format are adopted to solve the wellbore thermodynamic model and solve the wellbore temperature distribution; wherein, during the solution process, a successive super-relaxation iteration method based on the Gauss-Seidel iteration method is used for iterative solution.

[0023] In some embodiments, the control subsystem is further used to:

[0024] Displaying data of the wellbore temperature field parameters;

[0025] In response to a parameter adjustment instruction input by the user through the interactive control, the type of the displayed wellbore temperature field parameter is updated.

[0026] In a second aspect, the present application provides a cooling control method, which is applied to the control subsystem according to any one of the first aspects, and the method includes:

[0027] According to the wellbore thermodynamic model, the wellbore temperature distribution during the drilling fluid circulation process is obtained;

[0028] Based on the wellbore temperature distribution during the drilling fluid circulation process, the cooling parameters of the drilling fluid cooling subsystem and the lowering time and position of the heat shield drill rod of the downhole drill string are controlled.

[0029] In a third aspect, the present application provides a computer program product, including a computer program, which implements the method described in the second aspect when executed by a processor.

[0030] The cooling control method, drilling system and program product provided in the embodiments of the present application can realize active regulation of the temperature of the entire well. Through a series of combined means of ground cooling and downhole temperature control, the wellbore temperature is actively regulated in a coordinated and efficient manner for the ultra-high temperature environment downhole, thereby effectively reducing the ambient temperature at the bottom of the well. This is of vital importance for ensuring the temperature safety of a series of equipment such as downhole drilling tools, downhole measurement instruments, speed-up tools, and guide tools during the working process, and further ensuring the smooth progress of drilling operations and the effective acquisition of downhole actual drilling data.

[0031] The drilling system of the embodiment of the present application can cover the field of ultra-deep and extra-deep wells and geothermal wells, realize active regulation of the temperature of the entire well, and avoid downhole tools and equipment from failing due to the ultra-high temperature environment, affecting the normal advancement of drilling operations and the acquisition of downhole actual drilling parameters, so as to achieve safe and reliable drilling operations. At the same time, the "drilling system" can enable conventional downhole series of tools and equipment to meet the wellbore temperature control during the drilling of ultra-deep layers, geothermal wells, and even deep wells of 10,000 meters or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0033] Figure 1 A structural schematic diagram of a drilling system provided in an embodiment of the present application;

[0034] Figure 2 A structural schematic diagram of a drill rod provided in an embodiment of the present application;

[0035] Figure 3 A schematic diagram of the structure of a drilling instrument provided in an embodiment of the present application.

[0036] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0037] Drilling technology is mainly used in the exploitation of oil, natural gas, water wells, geothermal energy and mineral exploration. The main equipment used in the drilling process includes downhole tools, drilling fluid, guidance tools, and measurement while drilling instruments.

[0038] Downhole tools mainly include drill string, drill bit, stabilizer, drill collar and downhole motor. When working, the drill pipe with a drill bit at the end contacts the ground. The drill bit is responsible for breaking the formation rock and forming a wellbore; the stabilizer is used to maintain the stability of the drill string and prevent the wellbore from deflecting; the drill collar and downhole motor are responsible for transmitting drilling power and controlling the drilling direction. The drilling fluid is pumped from the ground into the drill string through the drilling pump, flows through the drill bit into the bottom of the wellbore, and then returns to the ground along the wellbore annulus. The drilling fluid has multiple functions, including cooling and lubricating the drill bit, carrying drill cuttings to the ground, and balancing the formation pressure. The steering tool is usually installed at the bottom of the drill string, close to the drill bit, and is used to control the drilling direction so that the wellbore is drilled according to the predetermined trajectory. The measurement while drilling instrument is also installed at the bottom of the drill string, close to the drill bit, usually installed above or near the steering tool. It can measure parameters such as wellbore trajectory, formation pressure, temperature and formation characteristics, helping the staff to adjust the drilling parameters in real time and improve drilling accuracy and safety.

[0039] As the exploration and development of oil and gas resources continues to deepen, the operating environment temperature of the wellbore is getting higher and higher. For the problem of high temperature in the underground environment during drilling, the main means of cooling the wellbore is to bring the heat to the ground through the circulation of drilling fluid, and then cool the drilling fluid through large-scale cooling equipment installed on the ground, using natural cooling, low-temperature medium mixed cooling and other cooling methods.

[0040] The above-mentioned wellbore cooling method has a low cooling range and cannot achieve a significant cooling. With the continuous increase in drilling depth, especially for ultra-deep wells and high-temperature geothermal wells, under the influence of the ultra-high temperature and harsh environment of the wellbore, the above-mentioned wellbore cooling method is difficult to ensure that the bottom hole temperature reaches the applicable temperature range of existing downhole tools, measuring instruments and material systems, and cannot meet the needs of ultra-high temperature well drilling, resulting in shortened service life of drilling tools, guide tools, downhole measurement and other instruments, increased failure rate, deterioration of drilling fluid performance, accelerated aging rate and other risks, which seriously affect and restrict the exploration, development and utilization of deep oil and gas and geothermal clean resources. In addition, due to the high cost of downhole equipment, once the equipment fails or is damaged, it will seriously affect the progress of drilling operations and increase drilling costs.

[0041] Since the drillable depth of drilling operations is severely limited by the development level of high-temperature resistant technology of drilling equipment, in order to achieve the goal of drilling into deeper formations and ensure that downhole drill tools, downhole instruments, downhole working fluids, etc. can adapt to the needs of ultra-high temperature formation drilling operations, this application proposes a "ground-downhole" collaborative drilling system that efficiently realizes full-well temperature control, which can enable downhole equipment to reach a safe operating temperature range and make conventional drilling technology equipment suitable for the wellbore temperature environment of ultra-deep wells and geothermal wells.

[0042] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0043] Figure 1 This is a structural diagram of a drilling system provided in an embodiment of the present application. The drilling system can be applied to fields such as oil and gas drilling and completion and geothermal well development.

[0044] like Figure 1 As shown, the drilling system may include: a control subsystem 101 , a ground drilling fluid cooling subsystem 102 , a drilling fluid delivery pipeline, a downhole drill string 103 , and a downhole while-drilling instrument 105 .

[0045] The control subsystem 101 is used to obtain the wellbore temperature distribution during the drilling fluid circulation process according to the wellbore thermodynamic model, and based on the wellbore temperature distribution during the drilling fluid circulation process, control the cooling parameters of the drilling fluid cooling subsystem 102, as well as the time and position of lowering the heat shield drill pipe.

[0046] The ground drilling fluid cooling subsystem 102 includes a plurality of cascaded cooling devices for performing graded cooling on the drilling fluid returned from the wellbore through the drilling fluid delivery pipeline based on cooling parameters, and re-injecting the cooled drilling fluid into the drilling fluid delivery pipeline in the wellbore.

[0047] The downhole drill string 103 is equipped with at least one heat shielding drill rod 104 for reducing the heat transferred from the high-temperature annulus to the inside of the drill string 103 .

[0048] The downhole drilling instrument 105 is equipped with a heat conduction device for reducing the amount of heat conducted by the external environment to the downhole drilling instrument.

[0049] The embodiments of the present application can effectively reduce the ambient temperature at the bottom of the well by combining ground cooling and downhole temperature control, so that the bottom of the well temperature reaches the temperature range applicable to existing downhole tools, measuring instruments and material systems.

[0050] The following is a detailed description of each part:

[0051] The control subsystem 101 is usually located on the ground, and includes a software system built based on a wellbore thermodynamic model, so that the control subsystem 101 can predict the wellbore temperature distribution during the drilling fluid circulation process through actual drilling data and the wellbore thermodynamic model.

[0052] The wellbore thermodynamic model can be a "heat-fluid-solid" multi-media coupled full wellbore thermodynamic model based on the "tubing-fluid" system, which comprehensively considers the influencing factors of the full wellbore temperature and heat transfer law. Among them, the influencing factors may include, for example: changes in the heat and mass transfer process of the "tubing-fluid-formation" downhole, changes in geothermal gradients, multiple heat sources downhole, changes in tubing structure and thermal conductivity, real-time conversion of drilling fluid rheological modes, multiphase flow in the wellbore, etc.

[0053] Optionally, the control subsystem 101 can also realize at least one of the following functions: string structure setting, basic parameter setting, visual display and other functions required for drilling temperature control. It should be noted that the factors that can be considered and paid attention to in the software establishment process include but are not limited to software implementation calculation speed, system function integrity and prediction data correction, etc.; the final goals achieved by the software may include but are not limited to complete thermodynamic calculation input and output parameter settings, fast solution calculation, dynamic visualization of calculation results, and prediction data can be used to dynamically correct the wellbore temperature distribution based on actual drilling data, etc., which can be set according to actual needs.

[0054] Through the wellbore thermodynamic model, the wellbore temperature distribution during the drilling fluid circulation process can be predicted, and based on the wellbore temperature distribution during the drilling fluid circulation process, the cooling parameters of the drilling fluid cooling subsystem 102 can be controlled to guide the temperature control process of the ground drilling fluid cooling subsystem 102. In addition, based on the wellbore temperature distribution during the drilling fluid circulation process, the time and position of lowering the heat shield drill rod of the downhole drill string can be guided.

[0055] For example, the wellbore thermodynamic model can be used to calculate and simulate the current temperature distribution of the wellbore based on actual drilling data, and the temperature distribution of the wellbore at the next moment can be predicted based on the current temperature distribution of the wellbore.

[0056] Subsequently, based on the real-time and predicted wellbore temperature distribution, the cooling parameters of the ground drilling fluid cooling subsystem 102 and the time and position of lowering the downhole drill string heat shield drill pipe are guided, thereby guiding the subsequent ground adjustment and downhole control of the drilling fluid temperature.

[0057] For example, the control subsystem 101 can obtain the number of axial grids and radial grids of the wellbore according to the drilling depth. The number of radial target position grids is greater than the number of bottom position grids; the target position includes at least one of the following: water hole, drill string, annulus and well wall.

[0058] That is, the control subsystem 101 can adopt a dynamic grid method to divide the axial grid of the wellbore, so that during the drilling process, the number of axial grids is updated in real time with the drilling depth to ensure the accuracy of the calculation; a non-uniform grid is adopted to divide the radial grid of the wellbore, the grids of the water hole, drill string, annulus and well wall are encrypted, and the grid of the formation position is gradually loosened, so as to ensure the speed of calculation.

[0059] Then, the control subsystem 101 can solve the wellbore thermodynamic model and the wellbore temperature distribution in a second-order upwind format and a fully implicit time format according to the number of axial grids and the number of radial grids; wherein, in the solution process, the successive super-relaxation iteration method modified on the basis of the Gauss-Seidel iteration method is used to iteratively solve the linear equations of the discrete equations. In this way, the calculation speed and accuracy of the wellbore temperature field can be improved.

[0060] Optionally, in some embodiments, the control subsystem further includes a display interface for displaying the data of the wellbore temperature field parameters, which can be adjusted by dividing the interface area to dynamically and visually display the output parameters at a suitable position. The switching of the display parameters in the main display area can be achieved by placing relevant virtual buttons. That is, in response to the parameter adjustment instruction input by the user through the interactive control, the type of the wellbore temperature field parameter displayed is updated.

[0061] The ground drilling fluid cooling subsystem 102 is located on the ground and may include multiple cascade cooling devices. Multiple cascade cooling devices may refer to cooling devices connected in sequence, wherein the outlet of the upper cooling device is connected to the inlet of the lower cooling device, and the outlet of the last cooling device is connected to the drilling fluid delivery pipeline located in the wellbore.

[0062] The ground drilling fluid cooling subsystem 102 can receive the cooling parameters sent by the control subsystem 101, and then control the cooling device to perform the graded cooling operation based on the cooling parameters, and re-inject the cooled drilling fluid into the drilling fluid delivery pipeline located in the wellbore to participate in the fluid circulation. By sequentially cooling the high-temperature drilling fluid in different cooling devices, the graded cooling of the drilling fluid can be achieved. Compared with cooling by a single cooling device, the purpose of significantly reducing the temperature can be achieved and the cooling effect of the drilling fluid can be improved.

[0063] Exemplarily, the control subsystem 101 may send a parameter adjustment instruction to the ground drilling fluid cooling subsystem 102, and the adjustment instruction may carry the above-mentioned cooling parameters, thereby guiding the ground drilling fluid cooling subsystem 102 to participate in the ground drilling fluid temperature adjustment.

[0064] The cooling parameter mentioned here may be a control parameter of the ground drilling cooling subsystem, which can make the drilling fluid reach the target temperature after being cooled by the ground drilling cooling subsystem. The control parameter can be specifically determined according to the cooling device used by the ground drilling cooling subsystem.

[0065] In a possible implementation, the cooling device may be an absorption heat pump. Through the technical solution and process flow of significantly cooling the surface of the drilling fluid based on the absorption heat pump, the different vapor pressures of salt solutions with different concentrations are used to achieve refrigeration. In this example, the cooling parameters may include, for example, the concentration of the salt solution of each cooling device and / or the cooling time.

[0066] Optionally, the ground drilling fluid cooling subsystem 102 may also be provided with a heat recovery device for recovering the heat released during the drilling fluid cooling process. This embodiment does not limit the recovery method, for example, the heat may be converted into electrical energy and provided to a device or system that needs power supply (such as a device for generating electricity at a well site), or the heat may be provided to a device or system that needs heating (such as a device for heating domestic water on site), etc.

[0067] Optionally, the ground drilling fluid cooling subsystem 102 can also monitor and evaluate the performance of the drilling fluid during the temperature adjustment process to make real-time adjustments based on the performance of the drilling fluid. For example, the performance parameters of the cooled drilling fluid are detected, the performance test results are output, and it is determined whether to re-inject the cooled drilling fluid into the wellbore based on the performance test results.

[0068] The above performance parameters may include, but are not limited to, density, viscosity, filtration loss, pH value, sand content, temperature, etc., to ensure that the performance of the drilling fluid meets the requirements of the drilling project. For how to detect the performance parameters of the cooled drilling fluid, please refer to the prior art, which is not limited thereto.

[0069] For example, if the requirements of the drilling project are met, the cooled drilling fluid is re-injected into the wellbore. If the requirements of the drilling project are not met, the cooled drilling fluid is treated to meet the requirements of the drilling project and then re-injected into the wellbore, or the unsatisfactory drilling fluid is discharged to avoid affecting the safety and effectiveness of the drilling operation.

[0070] In the well section, by installing at least one heat-shielding drill rod 104 at a suitable position of the downhole drill string 103, the heat-shielding drill rod can reduce the thermal conductivity of the drill string, thereby reducing the heat transferred from the high-temperature annulus to the inside of the drill string 103, that is, reducing the heat transferred from the high-temperature area of ​​the annulus to the water hole space in the drill string, thereby avoiding the low-temperature drilling fluid injected into the wellbore from being affected by the high-temperature environment during the flow to the bottom of the well, resulting in a significant increase in temperature.

[0071] The installation position of the heat shield drill rod 104 is related to the temperature distribution of the wellbore. For example, the heat shield drill rod 104 can be installed at a position where the temperature is greater than a preset threshold. Exemplarily, the control subsystem 101 can determine the position and time where the heat shield drill rod 104 needs to be installed based on the temperature distribution of the wellbore, and after marking the position and the time of installation in the wellbore model, output the wellbore model marked with the position and the time of installation, so that the installer can install the well based on the data.

[0072] The heat shielding drill rod 104 can be any drill rod capable of achieving heat shielding. For example, the heat shielding drill rod 104 can include: a drill rod 104 filled with heat insulation material, or a drill rod 104 with thermal barrier coating sprayed on the inner and outer walls.

[0073] The number of the heat shielding drill rods 104 can be determined according to the size of the drill string, so that the heat shielding drill rods 104 form a closed annular space in the drill string, reduce the overall thermal conductivity of the drill string, and isolate the heat transfer inside and outside the drill string.

[0074] Figure 2 A structural diagram of a drill rod provided in an embodiment of the present application is shown in FIG. Figure 2 As shown, the drill pipe 104 includes: an inner wall 201, an outer wall 202 and an annular space 203. The annular space 203 is a closed space filled with heat insulation material to isolate the heat transfer between the inside and outside of the drill pipe 104.

[0075] It should be understood that the above-mentioned thermal insulation material can be a low thermal conductivity material with good high temperature resistance, a wide operating temperature range, low density, excellent vibration resistance, and good high temperature durability, so as to fully adapt to the harsh environmental requirements underground.

[0076] Optionally, in some embodiments, for well sections with looser requirements for internal and external thermal insulation of the drill string, a drill pipe 104 with thermal barrier coating sprayed on the inner and outer walls may be used, and for well sections with higher requirements for thermal insulation, a drill pipe 104 filled with thermal insulation material may be used.

[0077] For example, limited by the inner and outer diameters of the drill string and the borehole size, the single-sided spraying thickness of the inner and outer walls of the drill string can be less than or equal to 0.5 mm to ensure operational safety.

[0078] In specific implementation, during the drilling process, on-site construction personnel replace conventional drill strings with thermal barrier drill pipes or thermal barrier coated drill pipes in sections underground, which can isolate the heat exchange between the water eye space and the annulus area to a large extent, reduce the temperature rise of the drilling fluid inside the water eye during the flow from the wellhead to the bottom of the well, and achieve the goal of adjusting the bottom hole temperature, while also changing the temperature distribution of the entire wellbore.

[0079] A heat conduction device is installed on the side of the downhole while drilling instrument 105 near the bottom of the well to reduce the amount of heat conducted by the external environment to the downhole while drilling instrument.

[0080] Figure 3 A structural diagram of a drilling instrument provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, the heat conduction device may be a heat conducting plate 302 ; the heat conducting plate 302 is respectively connected to the heating element 303 of the circuit compartment 301 of the while drilling instrument 105 and the circuit compartment wall.

[0081] For the measurement while drilling instrument 105 near the bottom of the well, under the influence of the high temperature environment at the bottom of the well and the heat accumulation during its own working process, it is easy to cause the risk of failure or even damage. By equipping the downhole measurement while drilling instrument 105 with a heat conduction device, the heat generated by the heating element 303 in the circuit compartment 301 of the downhole measurement while drilling instrument 105 can be quickly conducted to avoid the occurrence of heat accumulation.

[0082] The structure of the heat conducting plate 302 can be determined according to the structure of the circuit compartment 301 and the components 303 in the compartment to fully ensure good thermal conductivity. It should be understood that the heat conducting plate 302 can meet the following conditions including but not limited to: ultra-high thermal conductivity, excellent vibration / impact resistance, stable connection, non-magnetic, continuous and smooth thermal conductivity, uniform and rapid thermal conductivity, etc.

[0083] Exemplarily, the heat conducting plate 302 may be formed by combining a copper plate and a flexible graphene material, so that the heat conducting plate 302 has the characteristics of large heat flux, low density, excellent heat expansion performance, and simple design.

[0084] The heating element 303 is the hot end, the wall of the circuit cabin 301 is the cold end, and the heat conducting plate is the heat conduction path. The heat conducting plate 302 can be connected to the heating element 303 and the wall in the circuit cabin 301 of the drilling instrument by bolts, for example, to transfer the heat on the circuit board to the wall, so that the heat can be quickly transferred from the hot end to the cold end, thereby achieving the goal of conducting the heat generated by the element 303 at work.

[0085] Optionally, in some embodiments, the inner wall of the circuit compartment 301 of the drilling while drilling instrument 105 may be sprayed with a thermal barrier coating 304. In this way, the heat exchange between the inside and outside of the compartment can be isolated, so that the ambient temperature inside the circuit compartment 301 is kept within the rated operating temperature range of the instrument and equipment, and the temperature safety of the drilling while drilling instrument 105 during operation is guaranteed. That is, the heat exchange between the circuit compartment 301 of the drilling while drilling instrument and the external environment is reduced, the temperature inside the circuit compartment 301 is prevented from being too high, the risk of high-temperature failure of the working components in the circuit compartment 301 is reduced, and the temperature safety of the electronic components in the compartment is protected.

[0086] Optionally, in some embodiments, a cold source with an active cooling function is installed in the circuit compartment 301 of the drilling instrument 105 to realize "underground air conditioning" to increase the temperature difference between the hot end and the cold end, increase the heat conduction rate of the heat conducting plate 302, and achieve the purpose of faster lowering the working temperature of the element 303. The installation position of the cold source can be designed according to the size and position of the drilling instrument 105 and the circuit compartment 301, and is not limited to this.

[0087] At the position near the bottom of the well, the heat generated during the working process of the drilling instrument 105 is easy to accumulate and difficult to be quickly drained, resulting in the risk of failure or even damage of the drilling instrument 105 under the influence of the high temperature environment at the bottom of the well and the heat accumulation during its own working process. By equipping the drilling instrument 105 with a series of efficient heat drainage tools and equipment, as well as a cold source with active cooling function, the heat conduction of the external environment to the drilling instrument 105 can be greatly reduced while draining the heat, and the working temperature of the components in the drilling instrument circuit cabin 301 can be controlled within a reasonable range, ensuring the temperature safety of the drilling instrument 105 during the working process and avoiding failure or damage.

[0088] Optionally, on the basis of the above-mentioned cooling scheme, a phase change heat absorbing material can be further added to the drilling fluid. The phase change material sinks and floats with the drilling fluid in the wellbore. When the drilling fluid ambient temperature is higher than the material phase change threshold, the phase change material undergoes a phase change, absorbs the heat in the nearby drilling fluid, takes away the drilling fluid heat and returns to the wellbore with the drilling fluid, thereby achieving the purpose of reducing the wellbore temperature.

[0089] In specific implementation, according to the wellbore temperature control requirements, well depth, formation conditions, drilling fluid thermophysical properties, etc., qualified phase change materials can be reasonably selected to participate in the wellbore drilling fluid circulation, so as to avoid excessive annulus temperature and reduce the impact of high annulus temperature on drilling fluid performance, drilling tools, formations, etc.

[0090] For example, in order to ensure that the annulus temperature is not higher than 150°C, according to the requirements of wellbore safety temperature, well depth, drilling fluid performance, etc., when the circulating drilling fluid is returned to the ground, a phase change material with a phase change temperature of less than 150°C and strong heat absorption capacity is selected according to performance requirements and added to the drilling fluid, and enters the wellbore with the drilling fluid to participate in fluid circulation. When the drilling fluid leaves the internal space of the drill string at the bottom of the well and enters the annulus from the drill bit water hole, the drilling fluid temperature rises rapidly due to factors such as drill bit rock breaking and formation heat transfer. When the drilling fluid temperature is higher than the phase change temperature of the phase change material, the phase change material undergoes a phase change, greatly absorbing the heat in the drilling fluid in the nearby area, and controlling the drilling fluid temperature below the phase change temperature, thereby ensuring that the annulus temperature is not higher than 150°C.

[0091] The drilling system provided by the embodiment of the present application is described below by an example. In this example, the control subsystem can guide the three processes of cooling the high-temperature drilling fluid on the ground, inserting the heat shielding material of the drill string, and controlling the temperature of the phase change material downhole.

[0092] According to the bottom hole temperature required by the field staff, the cooling process of the ground drilling fluid cooling subsystem is calculated and judged, and the corresponding cooling parameters are transmitted to the ground drilling fluid cooling subsystem. After receiving the cooling parameters, the ground drilling fluid cooling subsystem adjusts the system parameters to control the inlet and outlet temperatures of the drilling fluid of the ground drilling fluid cooling subsystem in real time, so that the high-temperature drilling fluid returned from the wellbore annulus enters the ground drilling fluid cooling subsystem for cooling to the set temperature, and then the cooled low-temperature drilling fluid is injected into the wellbore again to participate in the fluid circulation process.

[0093] At the same time, the control subsystem guides the on-site construction personnel to lower the heat shield drill pipe at the right time and in the right position, thereby greatly reducing the heat exchange between the fluid inside and outside the drill pipe. At the same time, the heat conduction equipment in the circuit cabin of the drilling instrument timely, quickly and efficiently conducts the heat of the instrument during drilling. The thermal barrier coating sprayed on the inner wall of the circuit cabin isolates the heat exchange between the cabin and the outside, so that the ambient temperature inside the circuit cabin is always kept within the rated operating temperature range of the instrument and equipment, ensuring the temperature safety of the drilling instrument during operation.

[0094] In order to avoid the annulus from heating up due to downhole heat shielding, phase change functional materials are added into the drilling fluid as needed to participate in the wellbore fluid circulation, and the purpose of controlling the temperature of the wellbore circulating fluid is achieved through the phase change heat absorption principle.

[0095] The drilling system provided in the embodiment of the present application can realize active regulation of the temperature of the entire well. Through a series of combined means of ground cooling and downhole temperature control, the wellbore temperature is actively regulated in a coordinated and efficient manner for the ultra-high temperature environment downhole, thereby effectively reducing the ambient temperature at the bottom of the well. This plays a vital role in ensuring the temperature safety of a series of equipment such as downhole drilling tools, downhole measurement instruments, speed-up tools, and guide tools during the working process, and further ensuring the smooth progress of drilling operations and the effective acquisition of actual downhole drilling data.

[0096] The drilling system of this embodiment can cover the field of ultra-deep and extra-deep wells and geothermal wells, realize active regulation of the temperature of the entire well, and avoid downhole tools and equipment from failing due to the ultra-high temperature environment, affecting the normal advancement of drilling operations and the acquisition of downhole actual drilling parameters, so as to achieve safe and reliable drilling operations. At the same time, this "drilling system can enable conventional downhole series of tools and equipment to meet the wellbore temperature control during the drilling of ultra-deep layers, geothermal wells, and even deep wells of 10,000 meters or more.

[0097] The present application also provides a temperature reduction control method, which is applied to a control subsystem and includes:

[0098] According to the wellbore thermodynamic model, the wellbore temperature distribution during the drilling fluid circulation process is obtained;

[0099] Based on the wellbore temperature distribution during the drilling fluid circulation process, the cooling parameters of the drilling fluid cooling subsystem, as well as the lowering time and position of the heat shield drill rod of the downhole drill string are controlled.

[0100] Regarding how the control subsystem determines and controls the cooling parameters and the lowering time and position of the heat shield drill rod of the downhole drill string according to the wellbore thermodynamic model, reference may be made to the description of the aforementioned embodiment, which will not be elaborated herein.

[0101] The present application also provides a computer program product, including a computer program, which implements the above-mentioned method of controlling the subsystem when executed by a processor.

[0102] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above-mentioned method of controlling the subsystem is implemented.

[0103] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0104] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0105] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0106] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0107] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0108] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0109] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0110] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A drilling system, characterized in that: The system includes: a control subsystem, a ground drilling fluid cooling subsystem, a drilling fluid delivery pipeline, a downhole drill string, and a downhole drilling instrument; The surface drilling fluid cooling subsystem includes a plurality of cascaded cooling devices, which are used to perform graded cooling on the drilling fluid returned from the wellbore through the drilling fluid delivery pipeline based on the cooling parameters, and to re-inject the cooled drilling fluid into the drilling fluid delivery pipeline located in the wellbore; The downhole drill string is equipped with at least one heat shield drill rod, which is used to reduce the heat transferred from the high-temperature annulus to the inside of the drill string; The control subsystem is used to obtain the wellbore temperature distribution during the drilling fluid circulation process according to the wellbore thermodynamic model, and control the cooling parameters of the drilling fluid cooling subsystem and the lowering time and position of the heat shield drill rod based on the wellbore temperature distribution during the drilling fluid circulation process; The downhole drilling instrument is equipped with a heat conduction device for reducing the amount of heat conducted by the external environment to the downhole drilling instrument.

2. The system according to claim 1, characterized in that The surface drilling fluid cooling subsystem is also used to recover the heat released during the drilling fluid cooling process.

3. The system according to claim 1, characterized in that The surface drilling fluid cooling subsystem is also used for: Detecting the performance parameters of the cooled drilling fluid and outputting the performance test results; the performance parameters include: density, viscosity and temperature of the drilling fluid; Determine whether to re-inject the cooled drilling fluid into the wellbore according to the performance test result.

4. The system according to claim 1, characterized in that The heat shield drill pipe type includes: a drill pipe filled with heat insulation material, or a drill pipe with thermal barrier coating sprayed on the inner and outer walls.

5. The system according to claim 1, characterized in that The heat conduction device is a heat conduction plate; The heat conducting plates are respectively connected to the components of the circuit compartment and the circuit compartment wall of the while drilling instrument.

6. The system according to claim 5, characterized in that The inner wall of the circuit cabin of the drilling instrument is sprayed with a thermal barrier coating.

7. The system according to claim 5, characterized in that A cold source with an active cooling function is installed in the circuit compartment of the drilling instrument.

8. The system according to any one of claims 1 to 7, characterized in that: Phase change heat absorbing material is added into the drilling fluid.

9. A cooling control method, characterized in that: The method is applied to the control subsystem according to any one of claims 1 to 8, and the method comprises: According to the wellbore thermodynamic model, the wellbore temperature distribution during the drilling fluid circulation process is obtained; Based on the wellbore temperature distribution during the drilling fluid circulation process, the cooling parameters of the drilling fluid cooling subsystem and the lowering time and position of the heat shield drill rod of the downhole drill string are controlled.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method of claim 9 when being executed by a processor.

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