A method of obtaining a borehole temperature profile of a drill pipe and a method of obtaining a drill pipe

Abstract

The present application belongs to the field of oil, natural gas and geothermal well drilling, and particularly relates to a method for obtaining wellbore temperature distribution of drill pipe and a method for obtaining drill pipe, wherein the wellbore temperature distribution of drill pipe in different combinations is solved through a first energy conservation equation of drilling fluid inside the drill pipe, a second energy conservation equation of the drill pipe, a third energy conservation equation of drilling fluid in the annulus between the drill pipe and the well wall and a fourth energy conservation equation of the well wall. The present application obtains the temperature distribution of drill pipe in different combinations in the wellbore, so as to select a thermal barrier drill pipe meeting the temperature resistance requirement of downhole instrument operation, and has the advantage of reducing the economic cost of drilling operation.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas geothermal well drilling, specifically relating to a method for obtaining the wellbore temperature distribution of drill pipe and a method for obtaining drill pipe. Background Technology

[0002] Oil and gas security is a crucial cornerstone of energy security. As shallow conventional oil and gas reserves on land gradually deplete, oil and gas exploration is expanding into ultra-deep and extra-deep formations. Due to the influence of geothermal gradients, the deeper the wellbore, the higher the temperature inside the wellbore. Current drilling technology faces the following serious problems and technical challenges at high temperatures: (i) the measurement and control instruments and tools used during drilling malfunction at high temperatures; (ii) the service life of the drill bit is greatly reduced, and the wear rate of the drill bit is even higher due to the higher surface temperature of the drill bit; (iii) the properties of the drilling fluid change at high temperatures and cannot meet the requirements of the drilling process.

[0003] Drill pipe is a consumable industrial product and an important component and wear part of the drill string in oil and gas field drilling wells. High-temperature conditions place higher demands on the performance of drill pipe.

[0004] Chinese patent application CN112096303A discloses a heat-insulated drill pipe for cooling the wellbore of high-temperature wells and its preparation method; however, this patent only provides one type of heat-insulated drill pipe, and if heat-insulated drill pipes are used in all drill pipe applications, it will increase costs.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] To address the technical problems existing in the prior art, the present invention provides a method for obtaining the wellbore temperature distribution of drill pipe and a method for obtaining drill pipe. The method of the present invention can obtain the wellbore temperature distribution of different combinations of drill pipe, thereby enabling the selection of drill pipe that meets the temperature resistance requirements of downhole instruments and has the advantage of reducing drilling operation costs.

[0007] This invention includes the following technical solutions:

[0008] This invention provides a method for obtaining the wellbore temperature distribution of drill pipe, the method comprising the following steps:

[0009] The wellbore temperature distribution of different combinations of drill pipes is solved by using the first energy conservation equation of the drilling fluid inside the drill pipe, the second energy conservation equation of the drill pipe, the third energy conservation equation of the drilling fluid in the annulus between the drill pipe and the well wall, and the fourth energy conservation equation of the well wall.

[0010] Among them, the different combinations of drill rods are different combinations of drill rod structures connected with drill bits, and the different combinations of drill rod structures are different combinations of thermal barrier drill rod structures and non-thermal barrier drill rod structures.

[0011] Furthermore, the thermal barrier drill rod structure includes a thermal barrier drill rod structure with thermal insulation material, a thermal barrier drill rod structure with thermal insulation coating, a thermal barrier drill rod structure with thermal insulation material and thermal insulation coating, and a vacuum thermal barrier drill rod structure.

[0012] Furthermore, the thermal barrier drill rod structure of the thermal insulation material includes an inner tube, an outer tube, an annular space, and thermal insulation material. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The annular space is filled with thermal insulation material.

[0013] The thermal barrier drill rod structure with thermal insulation coating includes an inner tube, an outer tube, an annular space, and a thermal insulation coating. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The wall of the annular space is sprayed with a thermal insulation coating.

[0014] The thermal barrier drill rod structure with thermal insulation material and thermal insulation coating includes an inner tube, an outer tube, an annular space, thermal insulation material, and a thermal insulation coating. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The annular space is filled with thermal insulation material, and the walls of the annular space are sprayed with a thermal insulation coating.

[0015] The vacuum thermal barrier drill rod structure includes an inner tube, an outer tube, an annular space, and a vacuum. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The annular space is evacuated.

[0016] Furthermore, when solving the drill pipe structure using the first energy conservation equation of the drilling fluid inside the drill pipe, the second energy conservation equation of the drill pipe, the third energy conservation equation of the drilling fluid in the annulus between the drill pipe and the well wall, and the fourth energy conservation equation of the well wall, the wellbore temperature distribution of different combinations of drill pipes can be obtained by controlling the dimensional parameters and thermal conductivity of the drill pipe structure.

[0017] The dimensional parameters include: the inner radius r of the drilling fluid control body P inside the drill string. Pi and the outer radius r of the drill pipe control body P Po ;

[0018] The thermal conductivity includes: the thermal conductivity k of the drill pipe structural material. P ;

[0019] The wellbore temperature distribution includes: the temperature T of the drilling fluid inside the drill pipe structure. in and the temperature T of the annular drilling fluid a .

[0020] Furthermore, the drill pipe structure is divided into several control volumes P, the radius of which includes the inner and outer radii of the control volumes P, and the first energy conservation equation includes:

[0021]

[0022] Wherein, superscript 1 and superscript 0 represent two adjacent moments, π represents pi, Δz represents the height of the control volume P inside the drill string, c is the specific heat capacity of the drilling fluid, ρ is the density of the drilling fluid, and T Pi f is the temperature of the inner wall of the drill pipe structure. s The friction coefficient of the drilling fluid inside the drill pipe structure is given by Δt, where Δt represents the time interval, μ represents the drilling fluid viscosity, and v represents the friction coefficient of the drilling fluid inside the drill pipe structure. i h is the drilling fluid flow velocity. Pi This represents the convective heat transfer coefficient between the inner wall of the drill pipe structure and the drilling fluid inside. cρT represents the control volume at time 1. in , cρT represents the control volume at time P as 0. in , cρv represents the control volume from time P0 to time P1. i T in The change cρv represents the control volume from time P0 to time P1. i T in The change

[0023] [h Pi (T in -T Pi )] 0-1 This represents the time from control volume P0 to time 1 (h). Pi (T in -T Pi The change in )

[0024] This represents the time from control volume P0 to time 1. The change in quantity.

[0025] Furthermore, the drill pipe includes a drill pipe structure and a drill bit, and the second energy conservation equation includes an energy conservation equation for the drill pipe structure and an energy conservation equation for the drill bit. The energy conservation equation for the drill pipe structure includes:

[0026]

[0027] Among them, c P To control the specific heat capacity of volume P, ρ P To control the density of volume P, h Po T is the convective heat transfer coefficient between the outer wall of the drill pipe structure and the annular drilling fluid. P T represents the drill pipe temperature. s ′ represents the lower interface temperature of the drill pipe control body P, T N ′ represents the upper interface temperature of the drill pipe control body P. This represents TP at time 1 for control volume P. Represents TP at time 0 for control volume P, [k] P (T S ′+T N ′-2T P )] 0-1 This represents the time from control volume P0 to time k. P (T S ′+T N ′-2T P The change in ) [h Po (T a -T P )] 0-1 This represents the time from control volume P0 to time 1 (h). Po (T a -T P The change in ) [h Pi (T P -T in )] 0-1 This represents the time from control volume P0 to time 1 (h). Pi (T P -T in ) change

[0028] Furthermore, the drill bit energy conservation equation includes:

[0029]

[0030] Among them, Q rg This indicates the heat generated by friction between the drill bit and the formation.

[0031] Furthermore, the third energy conservation equation includes:

[0032]

[0033] Where, r ci h is the inner radius of the casing. ci T is the convective heat transfer coefficient between the inner wall of the well and the drilling fluid in the annulus. Po T represents the temperature of the outer wall of the drill pipe. ci The temperature of the inner wall of the well. cρT represents the control volume at time 1. a , cρT represents the control volume at time 1. a , cρv represents the control volume from time P0 to time P1. a T a The change cρv represents the control volume from time P0 to time P1. a Ta The change This represents the time from control volume P0 to time 1. The change in quantity.

[0034] Furthermore, the fourth energy conservation equation includes:

[0035]

[0036] Where, r f To determine the radius within the stratigraphic control volume, c f k′ is the specific heat capacity of the formation. P k′ is the thermal conductivity of the sleeve. w Let k′ be the heat transfer coefficient between the casing and the formation. e ρ is the thermal conductivity of the formation. f T represents the density of the near-surface layer. N "" indicates the upper interface of the near-annular stratum control volume, T S "" indicates the lower interface of the near-annular space control volume, T OFT To control the temperature of the formation outside the control body.

[0037] A second aspect of the present invention provides a method for obtaining drill pipe, comprising the above-described method for obtaining wellbore temperature distribution of drill pipe, and further comprising the following steps:

[0038] By combining the wellbore temperature distribution with the temperature resistance of the instruments used in actual drilling, the temperature T of the drilling fluid inside the drill pipe structure is selected. in and the temperature T of the annular drilling fluid a Drill pipes that are below and closest to the stated temperature resistance temperature.

[0039] By adopting the above technical solution, the present invention has the following advantages:

[0040] 1. The method of the present invention can obtain the temperature distribution inside the wellbore of different combinations of drill pipes, thereby enabling the selection of drill pipes that meet the temperature resistance requirements of downhole instruments, and has the advantage of reducing the cost of drilling operations.

[0041] 2. The method for obtaining drill pipe of the present invention selects the appropriate thermal barrier drill pipe by obtaining the temperature distribution of different combinations of drill pipe in the wellbore. This not only improves the operating temperature of downhole instruments and avoids damage to downhole instruments, but also has the advantage of low cost.

[0042] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a flowchart of a method for obtaining the wellbore temperature distribution of drill pipe according to an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the drill pipe in use in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the thermal barrier drill rod structure in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of heat transfer in the thermal barrier drill rod structure of an embodiment of the present invention;

[0048] In the diagram, 10 is the thermal barrier drill rod structure, 11 is the inner tube, 12 is the outer tube, 13 is the annular space, and 20 is the non-thermal barrier drill rod structure. Detailed Implementation

[0049] The following description provides many different embodiments or examples for implementing various features of the invention. The elements and arrangements described in the specific examples below are only for concise expression of the invention and are merely examples, not intended to limit the invention.

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] The first aspect of this embodiment provides a method for obtaining the wellbore temperature distribution of drill pipe, the method comprising the following steps: Figure 1 As shown, the wellbore temperature distribution of different combinations of drill pipes is solved by the first energy conservation equation of the drilling fluid inside the drill pipe, the second energy conservation equation of the drill pipe, the third energy conservation equation of the drilling fluid in the annulus between the drill pipe and the well wall, and the fourth energy conservation equation of the well wall.

[0052] Among them, the different combinations of drill pipes are different combinations of drill pipe structures connected to drill bits, and the different combinations of drill pipe structures are different combinations of thermal barrier drill pipe structure 10 and / or non-thermal barrier drill pipe structure 20. For example Figure 2 As shown, the drill pipe is composed of multiple thermal barrier drill pipe structures 10, multiple non-thermal barrier drill pipe structures 20, and a drill bit connected together. It should be noted that the illustrated structure is only one specific type of drill pipe structure and does not represent a limitation on the drill pipe.

[0053] Both ends of the thermal barrier drill rod structure 10 and the non-thermal barrier drill rod structure 20 are provided with male or female connectors. In this way, the thermal barrier drill rod structure 10 and the non-thermal barrier drill rod structure 20, the thermal barrier drill rod structure 10 and the thermal barrier drill rod structure 20, and the non-thermal barrier drill rod structure 20 and the non-thermal barrier drill rod structure 20 can be connected by male or female connectors.

[0054] It should be noted that the thermal barrier drill pipe structure 10 is a drill pipe structure specifically designed with appropriate structures and materials for thermal shielding; while the non-thermal barrier drill pipe structure 20 is a drill pipe structure without dedicated thermal shielding, and the non-thermal barrier drill pipe structure 20 can be a conventional drill pipe structure in the prior art. Thermal shielding should be understood as: the drill pipe structure has the ability to reduce the radial transmission of wellbore temperature, such as... Figure 4 As shown, this reduces heat transfer in the direction of the arrow.

[0055] Compared to the thermal barrier drill pipe structure 10, the thermal barrier drill pipe structure 10 is more complex to manufacture and uses more materials, resulting in higher costs. Therefore, if the entire drill pipe were to use the thermal barrier drill pipe structure 10, the cost would increase significantly. Therefore, this invention selects a combination drill pipe of thermal barrier drill pipe structure 10 and thermal barrier drill pipe structure 20 that meets the temperature distribution requirements of the thermal barrier drill pipe and the non-thermal barrier drill pipe in the wellbore, thus reducing costs.

[0056] Furthermore, the thermal barrier drill rod structure 10 includes a thermal barrier drill rod structure with thermal insulation material, a thermal barrier drill rod structure with thermal insulation coating, a thermal barrier drill rod structure with thermal insulation material and thermal insulation coating, and a vacuum thermal barrier drill rod structure.

[0057] Furthermore, such as Figure 3 As shown, the thermal barrier drill rod structure with thermal insulation material includes an inner tube 11, an outer tube 12, an annular space 13, and thermal insulation material. The inner tube 11 is coaxially arranged inside the outer tube 12, and an annular space 13 is formed between the outer tube 12 and the inner tube 11. The annular space 13 is filled with thermal insulation material. For the thermal barrier drill rod structure filled with thermal insulation material, during the heat transfer process from the high-temperature fluid environment in the annulus to the internal space of the thermal barrier drill rod structure, such as... Figure 4As shown, the heat will pass sequentially through the outer tube 12, the insulation material, and the inner tube 11, and then enter the interior of the thermal barrier drill rod structure. The overall thermal resistance of this heat transfer process includes the different thermal resistances of the outer tube 12, the insulation material, and the inner tube 11, among which the insulation material has the greatest thermal resistance. The integrated system composed of the outer tube 12, the insulation material, and the inner tube 11 can effectively prevent the heat transfer through the thermal barrier drill rod.

[0058] The thermal barrier drill rod structure with heat insulation coating includes an inner tube 11, an outer tube 12, an annular space 13, and a heat insulation coating. The inner tube 11 is coaxially arranged inside the outer tube 12, and an annular space 13 is formed between the outer tube 12 and the inner tube 11. The wall of the annular space 13 is sprayed with a heat insulation coating. In this structure, the heat of the high-temperature fluid environment in the annular space is transferred to the internal space of the thermal barrier drill rod structure in sequence through the outer tube 12, the heat insulation coating on the inner wall of the outer tube 12, the gas medium (such as air), the heat insulation coating on the outer wall of the inner tube 11, and the inner tube 11, and then enters the interior of the thermal barrier drill rod structure. The overall thermal resistance of this transfer process includes the thermal resistance of the outer tube 12, the thermal insulation coating on the inner wall of the outer tube 12, the gas medium (such as air), the thermal insulation coating on the outer wall of the inner tube 11, and the inner tube 11. Among these, the thermal resistance of the thermal insulation coating and the gas medium is greater. The specific value of the thermal resistance of the thermal insulation coating varies depending on its coating thickness. The integrated system consisting of the outer tube 12, the thermal insulation coating on the inner wall of the outer tube 12, the gas medium (such as air), the thermal insulation coating on the outer wall of the inner tube 11, and the inner tube 11 can effectively prevent heat transfer through the thermal barrier of the drill pipe.

[0059] The thermal barrier drill rod structure with thermal insulation material and thermal insulation coating includes an inner tube 11, an outer tube 12, an annular space 13, thermal insulation material, and a thermal insulation coating. The inner tube 11 is coaxially arranged inside the outer tube 12, and an annular space 13 is formed between the outer tube 12 and the inner tube 11. The annular space 13 is filled with thermal insulation material, and the walls of the annular space 13 are sprayed with a thermal insulation coating. In this structure, the heat from the high-temperature fluid environment in the annular space is transferred to the internal space of the thermal barrier drill rod structure in sequence. The heat transfer occurs through the outer tube 12, the inner wall insulation coating of the outer tube 12, the insulation material, the outer wall insulation coating of the inner tube 11, and the inner tube 11, before entering the interior of the thermal barrier drill rod structure consisting of the insulation material and the insulation coating. The overall thermal resistance of this transfer process includes the thermal resistance of the outer tube 12, the inner wall insulation coating of the outer tube 12, the insulation material, the outer wall insulation coating of the inner tube 11, and the inner tube 11. The insulation coating and the insulation material have greater thermal resistance. The combined system can effectively prevent the heat transfer through the thermal barrier drill rod structure consisting of the insulation material and the insulation coating.

[0060] The vacuum thermal barrier drill rod structure includes an inner tube 11, an outer tube 12, an annular space 13, and a vacuum. The inner tube 11 is coaxially arranged inside the outer tube 12, forming an annular space 13 between the outer tube 12 and the inner tube 11. The annular space 13 is evacuated. This structure primarily reduces heat conduction and convection by removing the medium from the annular space 13. Due to the vacuum environment, there is no heat conduction between the high-temperature fluid environment and the internal space of the vacuum thermal barrier drill rod structure; only a small amount of heat is transferred into the structure through thermal radiation. Preferably, to mitigate thermal radiation, the inner walls of the outer tube 12 and the outer walls of the inner tube 11 can be covered with a low-emissivity material (such as silver or aluminum plating) to reflect radiant heat and reduce the impact of thermal radiation on the internal temperature of the structure. Preferably, the vacuum thermal barrier drill rod structure is equipped with a valve to evacuate the annular space, which facilitates manufacturing and reduces costs.

[0061] Thermal barrier drill rod structures with thermal insulation materials, thermal barrier drill rod structures with thermal insulation coatings, thermal barrier drill rod structures with thermal insulation materials and thermal barrier coatings, and vacuum thermal barrier drill rod structures have different thermal barrier effects, and the costs of these four drill rod structures are also different. Therefore, in order to reduce costs, in addition to selecting thermal barrier drill rod structure 10 and non-thermal barrier drill rod structure 20, further selecting the most suitable thermal barrier drill rod structure type 10 has the advantages of improving thermal barrier effect and reducing costs.

[0062] Furthermore, when solving for the drill pipe structure using the first energy conservation equation of the drilling fluid inside the drill pipe, the second energy conservation equation of the drill pipe, the third energy conservation equation of the drilling fluid in the annulus between the drill pipe and the well wall, and the fourth energy conservation equation of the well wall, the wellbore temperature distribution of different combinations of drill pipes can be obtained by controlling the dimensional parameters and thermal conductivity of the drill pipe.

[0063] The dimensional parameters include: the inner radius r of the drilling fluid control body P inside the drill string. Pi and the outer radius r of the drill pipe control body P Po The thermal conductivity includes: the thermal conductivity k of the drill pipe structural material. P .

[0064] The drill pipe is assembled by connecting thermal barrier drill pipe structure 10 and / or non-thermal barrier drill pipe structure 20; therefore, there are many ways to assemble them, and the size of the drill pipe can also vary; therefore, the inner radius r of the control body P inside the drill string is controlled by controlling the drilling fluid. Pi The outer radius r of the drill pipe control body P Po Thermal conductivity k of drill pipe structural materials P To obtain different combinations of drill pipes.

[0065] The wellbore temperature distribution includes: the temperature T of the drilling fluid inside the drill pipe structure. in and the temperature T of the annular drilling fluid a .

[0066] Furthermore, the drill pipe is divided into several control volumes P, and the first energy conservation equation includes:

[0067]

[0068]

[0069] In this context, superscript 1 and superscript 0 represent two adjacent moments, π represents pi, and r Pi Let Δz represent the inner radius of control volume P, Δz represent the height of control volume P, c represent the specific heat capacity of drilling fluid, ρ represent the density of drilling fluid, and T represent the total heat capacity of drilling fluid. Pi f is the temperature of the inner wall of the drill pipe structure. s The friction coefficient of the drilling fluid inside the drill pipe structure is given by Δt, where Δt represents the time interval, μ represents the drilling fluid viscosity, and v represents the friction coefficient of the drilling fluid inside the drill pipe structure. i h is the drilling fluid flow velocity. Pi This represents the convective heat transfer coefficient between the inner wall of the drill pipe structure and the drilling fluid inside. cρT represents the control volume at time 1. in , cρT represents the control volume at time P as 0. in , cρv represents the control volume from time P0 to time P1. i T in The change cρv represents the control volume from time P0 to time P1. i T in The change in [h] Pi (T in -T Pi )] 0-1 This represents the time from control volume P0 to time 1 (h). Pi (T in -T Pi The change in ) This represents the time from control volume P0 to time 1. The change in quantity.

[0070] Furthermore, the drill pipe includes a drill pipe structure and a drill bit, and the second energy conservation equation includes an energy conservation equation for the drill pipe structure and an energy conservation equation for the drill bit. The energy conservation equation for the drill pipe structure includes:

[0071]

[0072] Where, r Po c represents the outer radius of the control volume P.P To control the specific heat capacity of volume P, ρ P To control the density of volume P, T P K represents the temperature of the drill pipe structure. P T represents the thermal conductivity of the drill pipe structural material. s ′ represents the lower interface temperature of the drill pipe control body P, T N ′ represents the upper interface temperature of the drill pipe control body P, h Po The convective heat transfer coefficient between the outer wall of the drill pipe structure and the drilling fluid in the annulus. This represents TP at time 1 for control volume P. T represents the time when the control volume P is 0. P ,,

[0073] [k P (T S ′+T N ′-2T P )] 0-1 This represents the time from control volume P0 to time k. P (T S ′+T N ′-2T P The change in ) [h Po (T a -T P )] 0-1 This represents the time from control volume P0 to time 1 (h). Po (T a -T P The change in ) [h Pi (T P -T in )] 0-1 This represents the time from control volume P0 to time 1 (h). Pi (T P -T in ) change

[0074] Furthermore, the drill bit energy conservation equation includes:

[0075]

[0076] Among them, Q rg This indicates the heat generated by friction between the drill bit and the formation.

[0077] Furthermore, the third energy conservation equation includes:

[0078]

[0079] Where, r ci h is the inner radius of the casing. ci T is the convective heat transfer coefficient between the inner wall of the well and the drilling fluid in the annulus.Po T represents the temperature of the outer wall of the drill pipe structure. ci The temperature of the inner wall of the well. cρT represents the control volume at time 1. a , cρT represents the control volume at time 1. a , cρv represents the control volume from time P0 to time P1. a T a The change cρv represents the control volume from time P0 to time P1. a T a The change This represents the time from control volume P0 to time 1. The change in quantity.

[0080] Furthermore, the fourth energy conservation equation includes:

[0081]

[0082] Where, r f To determine the radius within the stratigraphic control volume, c f k′ is the specific heat capacity of the formation. P k′ is the thermal conductivity of the sleeve. w Let k′ be the heat transfer coefficient between the casing and the formation. e ρ is the thermal conductivity of the formation. f T represents the density of the near-surface layer. N "" indicates the upper interface of the near-annular stratum control volume, T S "" indicates the lower interface of the near-annular space control volume, T OFT To control the formation temperature outside the control body, T f To control body temperature, This represents the temperature at time 1 for control volume P. [k′] represents the temperature at time 0 for control volume P. P (T s "+T N "-2T" f )] 0-1 This represents the time from control volume P0 to time k′. P (T s "+T N "-2T" f The change in [k′] e (T OFT -T f )] 0-1 This represents the time from control volume P0 to time k′. e (T OFT -T f The change in [k′]w (T f -T a )] 0-1 This represents the time from control volume P0 to time k′. w (T f -T a The change in ).

[0083] The second aspect of this embodiment provides a method for obtaining drill pipe, including the wellbore temperature distribution method for obtaining drill pipe as described above, and further including the following steps:

[0084] By combining the wellbore temperature distribution with the temperature resistance of the instruments used in actual drilling, drill pipes with wellbore temperature distributions lower than and closest to the stated temperature resistance are selected.

[0085] If a drill pipe is divided into several control volumes P, then the drill pipe will have at least P temperatures T of the drilling fluid inside the aforementioned temperature-resistant drill pipe structure. in and the temperature T of the annular drilling fluid a Then, by comparing the temperature resistance with the temperature T of the drilling fluid inside the drill pipe structure... in and the temperature T of the annular drilling fluid a In comparison, the temperature T of the drilling fluid inside the drill pipe structure was obtained that was lower than the stated temperature resistance temperature but close to it. in and the temperature T of the annular drilling fluid a The corresponding drill pipe.

[0086] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for obtaining the wellbore temperature distribution of drill pipe, characterized in that, The method includes the following steps: The wellbore temperature distribution of different combinations of drill pipes is solved by using the first energy conservation equation of the drilling fluid inside the drill pipe, the second energy conservation equation of the drill pipe, the third energy conservation equation of the drilling fluid in the annulus between the drill pipe and the well wall, and the fourth energy conservation equation of the well wall. Among them, the different combinations of drill rods are different combinations of drill rod structures connected with drill bits, and the different combinations of drill rod structures are different combinations of thermal barrier drill rod structures and non-thermal barrier drill rod structures. The thermal barrier drill rod structure includes a thermal barrier drill rod structure with thermal insulation material, a thermal barrier drill rod structure with thermal insulation coating, a thermal barrier drill rod structure with thermal insulation material and thermal insulation coating, and a vacuum thermal barrier drill rod structure. The thermal barrier drill rod structure of the thermal insulation material includes an inner tube, an outer tube, an annular space, and thermal insulation material. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The annular space is filled with thermal insulation material. The thermal barrier drill rod structure with thermal insulation coating includes an inner tube, an outer tube, an annular space, and a thermal insulation coating. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The wall of the annular space is sprayed with a thermal insulation coating. The thermal barrier drill rod structure with thermal insulation material and thermal insulation coating includes an inner tube, an outer tube, an annular space, thermal insulation material, and a thermal insulation coating. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The annular space is filled with thermal insulation material, and the walls of the annular space are sprayed with a thermal insulation coating. The vacuum thermal barrier drill rod structure includes an inner tube, an outer tube, an annular space, and a vacuum. The inner tube is coaxially arranged inside the outer tube, and an annular space is formed between the outer tube and the inner tube. The annular space is evacuated. When solving for the drill pipe structure using the first energy conservation equation of the drilling fluid inside the drill pipe, the second energy conservation equation of the drill pipe, the third energy conservation equation of the drilling fluid in the annulus between the drill pipe and the well wall, and the fourth energy conservation equation of the well wall, the wellbore temperature distribution of different combinations of drill pipes can be obtained by controlling the dimensional parameters and thermal conductivity of the drill pipe structure. The dimensional parameters include: drill pipe control body inner radius and drill pipe control body outer radius ; The thermal conductivity includes: the thermal conductivity of the drill pipe structural material. ; The wellbore temperature distribution includes: the temperature of the drilling fluid inside the drill pipe structure. and the temperature of the annular drilling fluid ; The drill pipe includes a drill pipe structure and a drill bit. The second energy conservation equation includes the energy conservation equation for the drill pipe structure and the energy conservation equation for the drill bit. The energy conservation equation for the drill pipe structure includes: ； in, For control body Specific heat capacity, For control body density, The convective heat transfer coefficient between the outer wall of the drill pipe structure and the drilling fluid in the annulus. For drill pipe temperature, For drill pipe control body The lower interface temperature, For drill pipe control body The upper interface temperature, Indicates control body Time is 1 , Indicates control body Time 0 , Indicates control body From time 0 to time 1 The change Indicates control body From time 0 to time 1 The change Indicates control body From time 0 to time 1 The change Indicates drill pipe control body height, Indicates a time interval.

2. The method for obtaining the wellbore temperature distribution of drill pipe according to claim 1, characterized in that, The drill pipe structure is divided into several control volumes. The first energy conservation equation includes: ; In this context, superscript 1 and superscript 0 represent two adjacent moments. Represents pi (π). The specific heat capacity of the drilling fluid. For drilling fluid density, This refers to the temperature of the inner wall of the drill pipe structure. The friction coefficient of the drilling fluid inside the drill pipe structure. Indicates the viscosity of the drilling fluid. The drilling fluid flow rate, This represents the convective heat transfer coefficient between the inner wall of the drill pipe structure and the drilling fluid inside. Indicates control body Time is 1 , Indicates control body Time 0 , This indicates that the drilling fluid flowing into the control volume from the top between time P0 and time 1 carries the control volume into the control volume. The increase; This indicates that from time P0 to time 1, drilling fluid flows out of the control volume from the bottom, carrying it out of the control volume. The reduction amount, In This represents the top interface of the control body. In This represents the top interface of the control body; Indicates control body From time 0 to time 1 The change Indicates control body 0:00 to 1:00 The change in quantity.

3. The method for obtaining the wellbore temperature distribution of drill pipe according to claim 1, characterized in that, The drill bit energy conservation equation includes: ； in, This indicates the heat generated by friction between the drill bit and the formation.

4. The method for obtaining the wellbore temperature distribution of drill pipe according to claim 1, characterized in that, The third energy conservation equation includes: ； in, The inner radius of the casing, The convective heat transfer coefficient between the inner wall of the well and the drilling fluid in the annulus. The temperature of the outer wall of the drill pipe. The temperature of the inner wall of the well. Indicates control body Time is 1 , Indicates control body Time 0 , Indicates control body From time 0 to time 1, the drilling fluid flowing from the bottom into the control body carries the fluid into the control body. The change Indicates control body From time 0 to time 1, drilling fluid flows out from the top, carrying the control body with it. The change Indicates control body From time 0 to time 1 The change in quantity.

5. The method for obtaining the wellbore temperature distribution of drill pipe according to claim 1, characterized in that, The fourth energy conservation equation includes: ； in, To control the radius within the formation. For the specific heat capacity of the formation, For the thermal conductivity of the sleeve, The heat transfer coefficient between the casing and the formation, For the thermal conductivity of the formation, The density of the near-surface layer, This represents the upper interface of the near-annular stratum control volume. This indicates the lower interface of the near-annular stratum control volume. To control the temperature of the formation outside the control body, To control the body temperature, Indicates control body The temperature at time 1. Indicates control body The temperature at time 0. Indicates control body From time 0 to time 1 The change Indicates control body From time 0 to time 1 The change Indicates control body From time 0 to time 1 The change in quantity.

6. A method for obtaining drill pipe, characterized in that, The method for obtaining the wellbore temperature distribution of drill pipe as described in any one of claims 1-5 further includes the following steps: The temperature distribution in the wellbore is combined with the temperature resistance of the instruments used in actual drilling. Select the temperature of the drilling fluid inside the drill pipe structure. and the temperature of the annular drilling fluid Drill pipes that are below and closest to the stated temperature resistance temperature.

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