A method and system for calculating the friction of a pipe string for constant pressure radial hydraulic drilling

Abstract

The application discloses a pipe string friction calculation method and system for constant-pressure radial hydraulic drilling, and the method comprises the following steps: designing a pipe string combination satisfying current constant-pressure radial hydraulic drilling, wherein the pipe string combination comprises oil pipes, titanium alloy pipes and jet nozzle drill bit combinations with different wall thicknesses, and a workover rig is used to control the lifting and lowering of the pipe string combination; according to the structural parameters and construction parameters of the pipe string combination, the friction resistance characteristic information of the horizontal section, the turning section and the vertical section in the current pipe string combination is respectively calculated; and based on the friction resistance characteristic information of each section, the drilling weight on bit of the pipe string is adjusted in real time by combining the overall stress condition of the current pipe string combination and the actual drilling characteristics. The application can calculate the pipe string friction of radial hydraulic drilling.

Description

Technical Field

[0001] This invention belongs to the field of radial drilling technology, and in particular relates to a method and system for calculating the friction of the tubing in constant pressure radial hydraulic drilling. Background Technology

[0002] In existing technologies, window-side drilling technology is often used to exploit oil and gas reservoirs in high-temperature, high-pressure, and ultra-deep wells.

[0003] Conventional sidetracking techniques mainly include: open-hole sidetracking with casing pull-out, forged and milled casing window sidetracking, and directional drilling window sidetracking. Currently, the more mature and commonly used directional drilling window sidetracking technique is the one with directional drilling window. Its main working principle is as follows: using surface work equipment, a guide tool is used to send the guide tool to a predetermined position inside the casing. Then, a milling tool is used to mill a window along the guide tool on the casing. Finally, a new wellbore is drilled through the window using a combination of drilling tools, including a drill bit. This technique is relatively complex, requiring steps such as fixing and connecting the directional drilling tool, opening the window, and repairing the window, thus demanding high precision in tool positioning. Furthermore, using directional drilling window sidetracking for oil and gas extraction results in higher overall operating and time costs, and a relatively lower oil and gas recovery rate.

[0004] In addition, unconventional sidetracking techniques mainly include: high-pressure water jet radial horizontal sidetracking and coiled tubing window sidetracking. The high-pressure water jet radial horizontal sidetracking technique works by using a high-pressure hose with a nozzle to break up rocks with the pressure of a high-pressure water jet, creating a small-diameter wellbore in the formation. This reduces flow resistance, increases the drainage area, and maximizes the exploitation of remaining oil reservoirs, thereby improving recovery rates. The coiled tubing window sidetracking technique works by using a measurement-while-drilling tool to identify the window point, then running and fixing a guide at the window point, milling the sidetracking window into the casing, and finally drilling a new wellbore using a coiled tubing sidetracking assembly. However, due to the high flexibility of coiled tubing, it is difficult to control the drilling pressure, and coiled tubing helical buckling can easily occur during drilling, hindering drilling progress.

[0005] The Tarim Basin's Tahe Oilfield is characterized by its deep burial (5300-8400m), high downhole temperature (120-180℃), and high bottom-hole pressure (55-90MPa), making it a typical high-temperature, high-pressure, ultra-deep well. The Tahe Oilfield is a fractured-vuggy carbonate reservoir with multiple stratigraphic sequences, a large stratigraphic span, and significant lithological variations. The reservoirs are dominated by large caverns, dissolution cavities, and fractures. Furthermore, the limestone geology is stable and drillable, but the reservoirs are highly heterogeneous, exhibiting random spatial distribution, which can lead to some wells being unable to successfully extract oil and gas after completion. For oil and gas extraction in the Tahe Oilfield, unconventional sidetracking techniques are commonly employed. In developing this invention, the inventors discovered that the Tahe Oilfield experiences problems such as limited radial hydraulic drilling footage, low rock-breaking jet velocity, and low operational efficiency when operating well depths exceed 6000m. In addition, the use of semi-rigid pipes with small outer diameter (outer diameter ≤ 25 mm, wall thickness ≤ 5 mm) and low yield strength during the operation will also lead to the above problems. Summary of the Invention

[0006] One of the technical problems to be solved by this invention is to provide a method for calculating the frictional resistance of a tubing string for constant pressure radial hydraulic drilling. This method includes: designing a tubing string assembly that meets the requirements of the current constant pressure radial hydraulic drilling, wherein the tubing string assembly includes tubing of different wall thicknesses, titanium alloy tubing, and a jet nozzle drill bit assembly; and using a workover rig to control the lifting and lowering of the tubing string assembly; calculating the frictional resistance characteristics of the horizontal, turning, and vertical sections of the current tubing string assembly based on its structural and construction parameters; and adjusting the drilling pressure of the tubing string in real time based on the frictional resistance characteristics of each section, combined with the overall stress condition of the current tubing string assembly and the actual drilling characteristics.

[0007] Preferably, the tubing friction calculation method for constant pressure radial hydraulic drilling provided in this embodiment of the invention further includes: determining the minimum drilling pressure for the current constant pressure radial hydraulic drilling and the actual drilling pressure acting on the first structure composed of titanium alloy tubing and jet nozzles by analyzing the force on the current tubing assembly based on the friction resistance data of each segment; determining whether the actual drilling pressure acting on the first structure is within the bearing capacity range of the tubing string while meeting the minimum drilling pressure required for the current drilling, based on the minimum drilling pressure and the actual drilling pressure acting on the first structure, so as to adjust the drilling pressure that can be provided for the current tubing assembly in real time.

[0008] Preferably, the tubing friction calculation method for constant pressure radial hydraulic drilling provided in this embodiment of the invention further includes: determining the maximum axial force of each well section based on the friction resistance data of each section; further obtaining the lifting force of the workover rig hook, the weight of the tubing, the viscous resistance of the fluid, and the steering resistance of the steering gear; based on this, using an expression containing the lifting force information of the workover rig hook to characterize the actual drilling pressure acting on the first structure; and combining the ultimate bearing capacity of the titanium alloy pipe to determine the lifting force of the workover rig hook corresponding to the condition that the minimum drilling pressure required for the current drilling is met, and the actual drilling pressure acting on the first structure is at the ultimate bearing capacity of the titanium alloy pipe, so as to control the drilling pressure by adjusting the lifting force of the workover rig hook in real time.

[0009] Preferably, the horizontal section of the tubing assembly includes a titanium alloy tubing and a jet nozzle drill bit assembly. The calculation of the frictional resistance characteristics of the horizontal section includes: calculating the friction coefficient of the drilling fluid flowing turbulently within the titanium alloy tubing and the friction coefficient of the fluid in the annulus based on the structural and construction parameters of the titanium alloy tubing and the jet nozzle drill bit assembly; further obtaining the frictional resistance of the fluid within the horizontal section and the frictional resistance of the fluid in the annulus; calculating the frictional resistance of the open hole wall to the titanium alloy tubing; and calculating the resistance acting on the jet drill bit based on the relationship between the nozzle displacement and the drill bit pressure drop.

[0010] Preferably, the frictional resistance of the horizontal segment is calculated using the following expression:

[0011]

[0012]

[0013] F f =μ t K t w e L t

[0014] Among them, F h f represents the frictional resistance of the fluid within the horizontal section. t The friction coefficient of drilling fluid in turbulent flow within a titanium alloy tube is represented by ρ, where ρ represents the density of the drilling fluid, and v represents the friction coefficient of the drilling fluid in turbulent flow. t The velocity of the fluid inside the titanium alloy tube is represented by v, and the lowering speed of the tube assembly is represented by d. t The inner diameter of the titanium alloy tube is represented by L, the length of the horizontal section is represented by F. l f represents the frictional resistance of the fluid within the horizontal annulus. l D0 represents the friction coefficient of the fluid inside the annulus of the titanium alloy tube, and v represents the outer diameter of the titanium alloy tube. a F represents the flow velocity of the fluid inside the annulus of the titanium alloy tube. fμ represents the frictional resistance between the open-hole wellbore and the titanium alloy casing. t K represents the coefficient of friction between the titanium alloy tube and the hole wall. t w represents the buoyancy coefficient. e L represents the weight per meter of titanium alloy tubing. t This indicates the length of the titanium alloy tube.

[0015] Preferably, the process of calculating the frictional resistance characteristics of the steering section includes: performing a force analysis on the steering section of the tubing assembly under normal stable radial drilling and the state of complete deformation of the titanium alloy tube in the internal slide of the steering gear, and determining the frictional resistance of the steering section by calculating the work done by the external force on the steering section during the process from no deformation to complete deformation.

[0016] Preferably, the frictional resistance of the steering segment is calculated using the following expression:

[0017]

[0018] Among them, F f The frictional resistance of the turning section is represented by F1, the axial thrust of the turning section from the upper vertical section, and the axial pressure of the turning section from the lower horizontal section. f represents the frictional resistance of the track on the turning section, and σ represents the frictional resistance of the track on the turning section. s δ represents the yield strength of the titanium alloy tube, r represents the outer radius of the steering section of the titanium alloy tube, δ represents the wall thickness of the titanium alloy tube, and R represents the radius of curvature of the steering gear.

[0019] Preferably, the vertical section of the tubing assembly includes tubing, tubing couplings, weighted tubing, transition joints, and a titanium alloy tube assembly. The calculation of the frictional resistance characteristics of the vertical section includes: calculating the frictional resistance of the fluid inside the tubing and the frictional resistance of the fluid in the annulus of the vertical section based on the structural and construction parameters of the vertical section; calculating the fluid pressure loss caused by tubing assemblies with different wall thicknesses and the pressure loss caused when fluid flows from the tubing into the titanium alloy tube; and determining the total fluid frictional resistance of the current vertical section as the sum of all types of frictional resistance and all types of pressure loss.

[0020] Preferably, the frictional resistance of the vertical segment is calculated using the following expression:

[0021]

[0022]

[0023] F = F g +Δp g-g ·S Δg +Δp s ·S Δs +F v

[0024] Among them, F g f represents the frictional resistance of the fluid within tubing assemblies with different wall thicknesses. g ρ represents the friction coefficient of drilling fluid in turbulent flow within tubing assemblies with different wall thicknesses, and v represents the density of the drilling fluid. i The velocity of the fluid inside the vertical section of the pipe is represented by v, and the lowering velocity of the pipe assembly is represented by d. g L represents the inner diameter of the oil pipe. g F represents the length of the tubing assembly. v f represents the frictional resistance of the fluid within the vertical annulus. v The friction coefficient of the fluid within the vertical annulus, v a D represents the flow velocity of the fluid within the vertical annulus. h D represents the inner diameter of the steering gear sleeve. g The outer diameter of the oil pipe is represented by F, and the total frictional resistance of the fluid in the current vertical section is represented by Δp. g-g S represents the fluid pressure loss caused by combinations of tubing with different wall thicknesses. Δg Δp represents the difference in cross-sectional area between tubing assemblies with different wall thicknesses. s S represents the fluid pressure loss caused by the fluid flowing from the weighted oil pipe into the titanium alloy pipe. Δs This indicates the difference in cross-sectional area between the weighted oil pipe and the titanium alloy pipe.

[0025] On the other hand, the present invention also provides a tubing friction calculation system for constant pressure radial hydraulic drilling, characterized in that the system includes the following modules: a tubing assembly determination module, which is used to design a tubing assembly that meets the requirements of the current constant pressure radial hydraulic drilling, and to control the lifting and lowering of the tubing assembly using a workover rig, wherein the tubing assembly includes tubing of different wall thicknesses, titanium alloy tubing, and jet nozzle drill bit assemblies; a friction calculation module, which is used to calculate the friction resistance characteristics of the horizontal section, turning section, and vertical section in the current tubing assembly according to the structural parameters and construction parameters of the tubing assembly; and a drilling pressure adjustment module, which is used to adjust the drilling pressure of the tubing in real time based on the friction resistance characteristics of each section, combined with the overall stress condition of the current tubing assembly and the actual drilling characteristics.

[0026] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0027] This invention proposes a method for calculating tubing friction resistance in constant-pressure radial hydraulic drilling, employing unconventional sidetracking techniques to achieve increased production in typical high-temperature, high-pressure, ultra-deep wells in the Tarim Oilfield. To meet existing radial drilling requirements, an innovative radial drilling technique combining a workover rig and tubing string assembly is proposed. Simultaneously, by calculating the frictional resistance of the tubing string assembly and considering its stress conditions, drilling pressure is controlled and adjusted. This improves the recovery rate of typical high-temperature, high-pressure, ultra-deep wells, increases oil and gas production, and reduces operational costs.

[0028] Other features and advantages of the invention will be set forth in the description which follows, 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 may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0029] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a step diagram illustrating the method for calculating the friction of a tubing string in constant-pressure radial hydraulic drilling according to an embodiment of this application.

[0031] Figure 2 This is a schematic diagram of the tubing assembly in the tubing friction calculation method for constant pressure radial hydraulic drilling according to an embodiment of this application.

[0032] Figure 3 This is a simplified force diagram of a titanium alloy tube micro-segment in the tube string friction calculation method for constant pressure radial hydraulic drilling according to an embodiment of this application.

[0033] Figure 4 This is a strain diagram of a titanium alloy tube micro-element in the tube string friction calculation method for constant pressure radial hydraulic drilling according to an embodiment of this application.

[0034] Figure 5 This is a block diagram of a tubing friction calculation system for constant pressure radial hydraulic drilling according to an embodiment of this application.

[0035] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale.

[0036] The list of reference numerals in the attached figures is as follows:

[0037] 31: Sleeve

[0038] 32: Oil pipe

[0039] 33: Pipe coupling

[0040] 34: Weighted oil pipe

[0041] 35: Adapter

[0042] 36: Titanium alloy tube

[0043] 37: Steering gear

[0044] 38: Track Detailed Implementation

[0045] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0046] Furthermore, the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0047] In existing technologies, window-side drilling technology is often used to exploit oil and gas reservoirs in high-temperature, high-pressure, and ultra-deep wells.

[0048] Conventional sidetracking techniques mainly include: open-hole sidetracking with casing pull-out, forged and milled casing window sidetracking, and directional drilling window sidetracking. Currently, the more mature and commonly used directional drilling window sidetracking technique is the one with directional drilling window. Its main working principle is as follows: using surface work equipment, a guide tool is used to send the guide tool to a predetermined position inside the casing. Then, a milling tool is used to mill a window along the guide tool on the casing. Finally, a new wellbore is drilled through the window using a combination of drilling tools, including a drill bit. This technique is relatively complex, requiring steps such as fixing and connecting the directional drilling tool, opening the window, and repairing the window, thus demanding high precision in tool positioning. Furthermore, using directional drilling window sidetracking for oil and gas extraction results in higher overall operating and time costs, and a relatively lower oil and gas recovery rate.

[0049] In addition, unconventional sidetracking techniques mainly include: high-pressure water jet radial horizontal sidetracking and coiled tubing window sidetracking. The high-pressure water jet radial horizontal sidetracking technique works by using a high-pressure hose with a nozzle to break up rocks with the pressure of a high-pressure water jet, creating a small-diameter wellbore in the formation. This reduces flow resistance, increases the drainage area, and maximizes the exploitation of remaining oil reservoirs, thereby improving recovery rates. The coiled tubing window sidetracking technique works by using a measurement-while-drilling tool to identify the window point, then running and fixing a guide at the window point, milling the sidetracking window into the casing, and finally drilling a new wellbore using a coiled tubing sidetracking assembly. However, due to the high flexibility of coiled tubing, it is difficult to control the drilling pressure, and coiled tubing helical buckling can easily occur during drilling, hindering drilling progress.

[0050] The Tarim Basin's Tahe Oilfield is characterized by its deep burial (5300-8400m), high downhole temperature (120-180℃), and high bottom-hole pressure (55-90MPa), making it a typical high-temperature, high-pressure, ultra-deep well. The Tahe Oilfield is a fractured-vuggy carbonate reservoir with multiple stratigraphic sequences, a large stratigraphic span, and significant lithological variations. The reservoirs are dominated by large caverns, dissolution cavities, and fractures. Furthermore, the limestone geology is stable and drillable, but the reservoirs are highly heterogeneous, exhibiting random spatial distribution, which can lead to some wells being unable to successfully extract oil and gas after completion. For oil and gas extraction in the Tahe Oilfield, unconventional sidetracking techniques are commonly employed. In developing this invention, the inventors discovered that the Tahe Oilfield experiences problems such as limited radial hydraulic drilling footage, low rock-breaking jet velocity, and low operational efficiency when operating well depths exceed 6000m. In addition, the use of semi-rigid pipes with small outer diameter (outer diameter ≤ 25 mm, wall thickness ≤ 5 mm) and low yield strength during the operation will also lead to the above problems.

[0051] Therefore, to address the aforementioned problems, this invention proposes a method and system for calculating tubing friction resistance in constant-pressure radial hydraulic drilling. This method and system employ unconventional sidetracking techniques to achieve increased production in typical high-temperature, high-pressure, ultra-deep wells like those in the Tarim Oilfield. To meet existing radial drilling requirements, it innovatively proposes a radial drilling technology combining a workover rig and tubing string assembly. Simultaneously, by calculating the friction resistance corresponding to the new tubing string assembly and considering the stress conditions of the assembly, drilling pressure is controlled and adjusted. This improves the recovery rate of typical high-temperature, high-pressure, ultra-deep wells, increases oil and gas production, and reduces operational costs.

[0052] Example 1

[0053] Figure 1 This is a step diagram illustrating the method for calculating the friction of a tubing string in constant-pressure radial hydraulic drilling according to an embodiment of this application. Figure 2 This is a schematic diagram of the tubing assembly in the tubing friction calculation method for constant pressure radial hydraulic drilling according to an embodiment of this application. See below for reference. Figure 1 and Figure 2 This will explain each step of the method.

[0054] like Figure 1 As shown, in step S110, a tubing assembly is designed to meet the requirements of constant pressure radial hydraulic drilling. The newly designed tubing assembly includes tubing of varying wall thicknesses, titanium alloy tubing, and a jet nozzle drill bit assembly, and a workover rig is used to control the raising and lowering of the tubing assembly. Figure 2 As shown in this embodiment, one end of the tubing 32 is connected to one end of the weighted tubing 34 and fixed using a tubing coupling 33 to obtain a tubing assembly with different wall thicknesses. Simultaneously, one end of the titanium alloy tube 36 is connected to the jet nozzle drill bit, and the other end is connected to the remaining end of the weighted tubing 34 in the tubing assembly using a conversion connector 35. This results in a tubing string assembly that meets the requirements of constant pressure radial hydraulic drilling. This tubing string assembly is used for drilling operations after the casing 31 is opened. During the operation, the titanium alloy tube 36 undergoes plastic deformation as it passes through the steering mechanism 37, and the steering mechanism 37 is used to orient the titanium alloy tube 36. Preferably, a workover rig is used as the surface equipment for lifting the tubing string assembly to control the lifting and lowering of the designed tubing string assembly.

[0055] Further, in step S120, based on the structural and construction parameters of the tubing assembly designed in step S110, the frictional resistance characteristics of the horizontal, turning, and vertical sections in the current tubing assembly are calculated respectively. Specifically, the tubing assembly in step S110 is divided into horizontal, turning, and vertical sections, and corresponding frictional resistance calculation models are established for each of these three processes, and the frictional resistance of each section is calculated and analyzed. Since the titanium alloy tube 36 is drilled in the open hole in the horizontal section, the frictional resistance of the open hole wall to the titanium alloy tube 36 and the pressure drop resistance of the jet nozzle are relatively large, so a frictional resistance calculation model for the horizontal section is established based on the aforementioned factors; in addition, since the turning resistance of the titanium alloy tube 36 inside the turning device 36 directly affects whether the titanium alloy tube 36 can pass through the turning device 37 for hydraulic drilling, a frictional resistance calculation model for the turning section is established based on the aforementioned factors; and since the viscous resistance of the fluid inside and outside the tubing and the pressure drop resistance caused by the change in the cross-sectional dimensions of different tubing sections are relatively large, a frictional resistance calculation model for the vertical section is established based on the aforementioned factors.

[0056] Further, the horizontal section of the tubing assembly in step S110 includes the horizontal section of the titanium alloy tube 36 and the jet nozzle drill bit connected to it; the turning section of the tubing assembly in step S110 includes the plastic deformation portion of the titanium alloy tube 36 in the internal slide of the turner 37; the vertical section of the tubing assembly in step S110 includes the tubing assembly, the conversion joint 35, and the vertical section of the titanium alloy tube 36. Next, using the established friction resistance calculation models for the horizontal, turning, and vertical sections, the structural parameters of the casing 31, tubing 32, weighted tubing 34, titanium alloy tube 36, turner 37, track 38, and jet nozzle in the current tubing assembly, as well as the drilling fluid density and open hole diameter of the working well during the operation, are substituted into the corresponding friction resistance calculation models to obtain the friction resistance data for the horizontal, turning, and vertical sections in the current tubing assembly.

[0057] The resistance generated during constant-pressure radial hydraulic drilling mainly includes: the viscous resistance of the fluids inside and outside the tubing assembly, the frictional resistance of the open hole wall on the horizontal section of the titanium alloy tubing 36, the pressure drop resistance of the jet nozzle, the steering resistance of the titanium alloy tubing 36 inside the steering device 37, and the pressure drop resistance caused by changes in the cross-sectional dimensions of different tubing strings. The viscous resistance of the fluids inside and outside the tubing assembly consists of the frictional resistance of the fluid inside the tubing and the frictional resistance of the fluid in the annulus. It should be noted that during constant-pressure radial hydraulic drilling, to ensure that the water power of the jet nozzle meets the rock-breaking requirements, operations are usually carried out under conditions of high displacement and high flow velocity. Therefore, the flow pattern of the fluid inside the tubing is always in a turbulent flow state. Therefore, in this embodiment, the drilling fluid is considered an incompressible Newtonian fluid, and the effect of temperature is not considered.

[0058] Next, the resistance calculation process of the horizontal section in the tubular assembly in step S120 will be explained in detail.

[0059] By analyzing the resistance characteristics of the entire tubing assembly, the frictional resistance characteristics of the horizontal section within the assembly were obtained. These characteristics include: the frictional resistance of the fluid within the horizontal section, the frictional resistance of the fluid within the annulus, the frictional resistance of the open hole wall against the titanium alloy tubing 36, and the resistance acting on the jet drill bit.

[0060] Furthermore, in calculating the frictional resistance of the fluid within the horizontal section, the length of the horizontal section and the lowering speed of the tubing assembly are determined using construction parameters. Simultaneously, the turbulent flow velocity within the 36-meter horizontal section of the titanium alloy tubing and the flow velocity within the annulus are calculated separately. Using the friction coefficient of the drilling fluid in the turbulent flow within the 36-meter horizontal section of the titanium alloy tubing and the friction coefficient of the fluid within the annulus of the 36-meter horizontal section of the titanium alloy tubing, the frictional resistance of the fluid within the horizontal section is calculated based on the Fanning equation.

[0061] Furthermore, the frictional resistance of the drilling fluid in the turbulent flow within the 36-level horizontal section of the titanium alloy tubing is calculated using the following expression:

[0062]

[0063]

[0064] Among them, F h f represents the frictional resistance of the fluid within the horizontal section. t The friction coefficient of drilling fluid in turbulent flow within a titanium alloy tube is represented by ρ, where ρ represents the density of the drilling fluid, and v represents the friction coefficient of the drilling fluid in turbulent flow. t The velocity of the fluid inside the titanium alloy tube is represented by v, and the lowering speed of the tube assembly is represented by d. t The inner diameter of the titanium alloy tube is represented by L, the length of the horizontal section is represented by Δ, and the absolute roughness of the titanium alloy tube wall is represented by Δ.

[0065] Furthermore, the frictional resistance of the fluid within the horizontal annulus of the titanium alloy tube 36 is calculated using the following expression:

[0066]

[0067]

[0068] Among them, F l f represents the frictional resistance of the fluid within the horizontal annulus. l The coefficient of friction of the fluid inside the annulus of a titanium alloy tube, v a The flow velocity of the fluid inside the annulus of the titanium alloy tube is represented by D0, the outer diameter of the titanium alloy tube is represented by L, and the length of the horizontal section is represented by d. h Indicates the diameter of the naked eye.

[0069] Furthermore, the frictional resistance of the open-hole wall to the 36 horizontal section of the titanium alloy casing is calculated using the following expression:

[0070]

[0071] F f =μ t K t w e L t (6)

[0072] Among them, K t ρ represents the buoyancy coefficient. t F represents the density of titanium alloy tubes. f μ represents the frictional resistance between the open-hole wellbore and the titanium alloy casing. t w represents the coefficient of friction between the titanium alloy tube and the hole wall. e L represents the weight per meter of titanium alloy tubing. tThis indicates the length of the titanium alloy tube.

[0073] Next, based on the relationship between the nozzle displacement and the pressure drop of the jet drill bit, the resistance acting on the jet drill bit is calculated. In the embodiments of this application, a self-propelled jet drill bit is preferably used for hydraulic drilling. It should be noted that this application does not specifically limit the selection of the type of jet drill bit, and those skilled in the art can select it according to actual needs.

[0074] Furthermore, the resistance acting on the jet drill bit is calculated using the following expression:

[0075]

[0076]

[0077] Where, Δp z Q represents the pressure drop of the jet drill bit. z denoted by , C represents the nozzle flow rate, d represents the diameter of the nozzle outlet, and F represents the resistance experienced by the jet drill bit.

[0078] Next, the resistance calculation process of the steering section in the tubing assembly in step S120 will be explained in detail.

[0079] By analyzing the resistance characteristics of the overall column assembly, the frictional resistance characteristics of the steering section within the column assembly are obtained. Specifically, the frictional resistance characteristics of the steering section include the steering resistance of the titanium alloy tube 36 within the steering gear 37.

[0080] Furthermore, a stress analysis is performed on the steering section of the tubing assembly during normal, stable radial drilling, and also on the titanium alloy tube in the state of complete deformation within the steering mechanism's internal slide. The work done by external forces on the steering section during the process from no deformation to complete deformation is calculated to determine the frictional resistance of the steering section. In this embodiment, during normal, stable radial drilling of the tubing assembly's steering section, before the titanium alloy tube 36 steering section deforms, a stress analysis is performed on the titanium alloy tube 36 steering section and the jet drill bit system. This clarifies that the titanium alloy tube 36 steering section and the jet drill bit system are in a state of force equilibrium under the current conditions, and the frictional resistance of the track on the steering section during this process is calculated. Next, the process from the initial deformation to complete deformation of the titanium alloy tube 36 steering section under normal, stable radial drilling conditions is analyzed. During this process, the system only has plastic strain energy and the total potential energy change is zero. The plastic strain energy of the system at this time is the work done by external forces during this process, and this external force is determined as the frictional resistance of the steering section during this process. These two parts of frictional resistance constitute the frictional resistance of the entire steering section.

[0081] Figure 3This is a simplified force diagram of a titanium alloy tube micro-segment in the tube string friction calculation method for constant pressure radial hydraulic drilling according to an embodiment of this application. Figure 3 As shown, the titanium alloy tube 36 steering section is divided into several micro-segments (sub-segments), and each micro-segment is taken as the research object to analyze the force on the steering section located in the guide rail of the steering device 37 during normal stable radial drilling. A small section of the curved section of the titanium alloy tube 36 steering section is selected as a micro-segment. The analysis shows that it is subjected to the axial thrust F1 of the upper oil pipe 32, the axial pressure F2 of the horizontal section at the lower end, and the normal pressure N and frictional force f of the track 38. During normal stable radial drilling, the titanium alloy tube 36 steering section and the jet drill bit system are in a state of force equilibrium.

[0082] Figure 4 This is a strain diagram of a titanium alloy tube micro-element in the tube string friction calculation method for constant pressure radial hydraulic drilling, as described in an embodiment of this application. Figure 4 As shown, when the titanium alloy tube 36 steering segment undergoes complete deformation within the guide rail of the steering gear 37, the portion near the bending center is under compression, while the portion away from the bending center is under tension, with the center line of the titanium alloy tube 36 steering segment as the boundary. It should be noted that, ideally, when the titanium alloy tube 36 steering segment reaches the plastic deformation state, the axial stress at each point of the selected micro-element section is equal to the yield strength of the titanium alloy tube 36 steering segment. Since the radial drilling process is normally stable, according to the principle of energy conservation, the total potential energy change of the steering segment is zero; at this point, the work done by the external force is equal to the plastic strain energy.

[0083] Combining F1, F2, N, and f yields the following relation:

[0084] f = μ·N g (9)

[0085]

[0086] Where f represents the frictional resistance of the track to the turning section, μ represents the friction coefficient between the titanium alloy tube and the track wall, and N g F1 represents the supporting force of the track on the turning section, F2 represents the axial thrust of the turning section on the upper vertical section, F2 represents the axial pressure of the turning section on the lower horizontal section, and θ represents the inclination angle of the two cross sections of the micro-element segment.

[0087] In this embodiment, the influence of fluid resistance within the steering section is not considered. Therefore, the steering resistance of the titanium alloy tube 36 steering section by the steering gear 37 is the frictional resistance of the steering section, and the frictional resistance of the steering section is calculated using the following expression:

[0088]

[0089] dW = (F1 - F2 - ff) p)dl (12)

[0090]

[0091] Where U represents the plastic strain energy of the titanium alloy tube after plastic deformation, δ represents the wall thickness of the titanium alloy tube, and r represents the outer radius of the turning section of the titanium alloy tube. Let represent the central angle corresponding to the infinitesimal segment where the external force acts during radial drilling, l represent the distance of the infinitesimal segment where the external force acts during radial drilling, W represent the work done by the external force during radial drilling, and f represent the distance of the infinitesimal segment where the external force acts during radial drilling. p This represents the frictional resistance of the titanium alloy tube during the process from the initial deformation to complete deformation within the steering gear; R represents the radius of curvature of the steering gear; F represents the frictional resistance. f σ represents the frictional resistance during the steering segment. s This indicates the yield strength of the titanium alloy tube.

[0092] Next, the resistance calculation process of the vertical section in the tubular assembly in step S120 will be explained in detail.

[0093] By analyzing the resistance characteristics of the overall tubing assembly, the frictional resistance characteristics of the vertical sections within the assembly are obtained. These characteristics include: the frictional resistance of the fluid within the vertical section, the frictional resistance of the fluid within the annulus, the fluid pressure loss caused by tubing assemblies with different wall thicknesses, and the pressure loss caused by the fluid flowing from tubing 32 into the vertical section of titanium alloy tubing 36. After calculating the frictional resistance characteristics of each type of vertical section, the sum of all types of frictional resistance and all types of pressure loss is determined as the total fluid frictional resistance of the current vertical section.

[0094] Furthermore, the vertical section of the tubing assembly includes a combination of tubing 32, tubing coupling 33, weighted tubing 34, transition joint 35, and titanium alloy tubing 36. In calculating the frictional resistance of the fluid within the vertical section, the length of the tubing assembly in the vertical section is first determined using construction parameters, and the turbulent flow velocity within the tubing assembly and the flow velocity within the annulus are calculated separately. Then, using the friction coefficients of the drilling fluid flowing turbulently within tubing assemblies with different wall thicknesses and the friction coefficients of the fluid within the annulus of the vertical section, the frictional resistance of the fluid within the vertical section corresponding to the two friction coefficients is calculated based on the Fanning equation.

[0095] Furthermore, the frictional resistance of the drilling fluid in the vertical section of the turbulent flow within the tubing assembly is calculated using the following expression:

[0096]

[0097]

[0098]

[0099] Among them, F g f represents the frictional resistance of the fluid within tubing assemblies with different wall thicknesses. g The coefficient of friction, v, represents the friction coefficient of drilling fluid in turbulent flow within tubing assemblies with different wall thicknesses. i d represents the flow velocity of the fluid inside the vertical section of the pipe. g L represents the inner diameter of the oil pipe. g The length of the tubing assembly is represented by Q, the flow rate of the drilling fluid is represented by Re, the Reynolds number of the fluid is represented by μ, and the viscosity of the drilling fluid is represented by μ.

[0100] It should be noted that regardless of whether the drilling fluid injected in the actual construction operation is a Newtonian fluid or a non-Newtonian fluid, the frictional resistance of the vertical section in this application can be calculated according to the above method.

[0101] Furthermore, the frictional resistance of the fluid within the vertical annulus is calculated using the following expression:

[0102]

[0103]

[0104]

[0105] Among them, F v f represents the frictional resistance of the fluid within the vertical annulus. v The friction coefficient of the fluid within the vertical annulus, v a D represents the flow velocity of the fluid within the vertical annulus. h D represents the inner diameter of the steering gear sleeve. g L represents the outer diameter of the oil pipe. g d represents the length of the tubing assembly. h Indicates the diameter of the naked eye.

[0106] Next, it is necessary to calculate the fluid pressure loss caused by tubing assemblies with different wall thicknesses, and the pressure loss caused when fluid flows from tubing 32 into the vertical section of titanium alloy tubing 36. In this embodiment, since tubing 32 is lightweight and has a low load-bearing capacity, using only tubing 32 in the tubing string assembly would directly result in the vertical section of the assembly also having a low load-bearing capacity. To avoid this problem, a tubing assembly consisting of tubing 32 with different wall thicknesses and a weighted tubing 33 is used. In this tubing assembly, tubing 32 and weighted tubing 33 have different cross-sectional dimensions. During the process of drilling fluid flowing from tubing 32 into weighted tubing 33, the change in cross-sectional dimensions will cause fluid pressure loss. In this embodiment, it is necessary to calculate the fluid pressure loss in the tubing assembly according to Bernoulli's equation and the following expression:

[0107]

[0108]

[0109]

[0110] Where Δp represents the fluid pressure loss caused by the change in cross-sectional dimensions, Δp g-g The value represents the fluid pressure loss caused by the combination of oil pipes with different wall thicknesses. v1 and v2 represent the fluid velocities in the oil pipe and the weighted oil pipe, respectively. d1 and d2 represent the inner diameters of the oil pipe and the weighted oil pipe, respectively. ξ represents the local resistance coefficient of the vertical section.

[0111] Similarly, the vertical section from the heavy-duty tubing 34 with a large cross-section to the titanium alloy tubing 36 with a small cross-section also results in pressure loss of the drilling fluid. Therefore, in this embodiment of the invention, it is also necessary to calculate the fluid pressure loss due to the reduction in local cross-sectional area using the following expression:

[0112]

[0113]

[0114] Where, Δp s This represents the pressure loss caused by the fluid flowing from the oil pipe into the titanium alloy pipe, where g represents the acceleration due to gravity. The h values ​​represent the fluid velocities inside the weighted oil pipe and the titanium alloy pipe, respectively. s d represents the head loss due to changes in the dimensions of two cross sections. g d t These represent the inner diameters of the weighted oil pipe and the titanium alloy pipe, respectively.

[0115] Finally, the sum of all types of frictional resistance and all types of pressure loss in the vertical segment is determined as the total fluid frictional resistance of the current vertical segment. At this point, the total fluid frictional resistance of the vertical segment is:

[0116] F = F g +Δp g-g ·S Δg +Δp s ·S Δs +F v (25)

[0117] Where F represents the total frictional resistance of the fluid in the current vertical segment, and S Δg S represents the difference in cross-sectional area between tubing assemblies with different wall thicknesses. Δs This indicates the difference in cross-sectional area between the weighted oil pipe and the titanium alloy pipe.

[0118] Furthermore, in step S130, based on the frictional resistance characteristics of each segment, combined with the overall stress situation of the current tubing assembly and actual drilling characteristics, the drilling pressure of the tubing string is adjusted in real time. Specifically, based on the frictional resistance characteristics of each segment calculated in step S120, and combined with the actual drilling characteristics, the workover rig is structurally modified, and the drilling pressure of the tubing string is adjusted slightly in real time using a pressure control tool downhole. Thus, the drilling pressure is controlled and adjusted in real time using the workover rig and the downhole pressure control tool.

[0119] Furthermore, based on the frictional resistance data of each segment, the minimum drilling pressure required for the current constant pressure radial hydraulic drilling and the actual drilling pressure acting on the first structure composed of titanium alloy tubing and jet nozzles are determined through stress analysis of the current tubing assembly. Based on the minimum drilling pressure and the actual drilling pressure acting on the first structure, it is determined whether the actual drilling pressure acting on the first structure is within the bearing capacity of the tubing while meeting the minimum drilling pressure required for the current drilling, so as to adjust the drilling pressure that can be provided for the current tubing assembly in real time.

[0120] In this embodiment, specifically, a stress analysis is first performed on the current tubing string assembly to determine the minimum drilling pressure required for constant-pressure radial hydraulic drilling, as well as the actual drilling pressure acting on the first structure composed of titanium alloy tubing and jet nozzles. Then, the minimum drilling pressure is compared with the actual drilling pressure acting on the first structure. If the actual drilling pressure is greater than the minimum drilling pressure, it indicates that the current actual drilling pressure can be adjusted. Based on this, the current actual drilling pressure is further compared with the ultimate bearing capacity of the tubing string to determine whether the actual drilling pressure is within the ultimate bearing capacity range of the tubing string. If the current actual drilling pressure is within the ultimate bearing capacity range of the tubing string, the drilling pressure of the current tubing string assembly is adjusted in real time. Conversely, if the current actual drilling pressure is less than or equal to the minimum drilling pressure or exceeds the ultimate bearing capacity of the tubing string, the workover rig structure needs to be improved, and the current drilling pressure needs to be adjusted slightly in real time using downhole pressure control tools.

[0121] Furthermore, based on the frictional resistance data of each section, the maximum axial force of each well section is determined. The lifting force of the workover rig hook, the weight of the tubing, the viscous resistance of the fluid, and the steering resistance of the steering gear are then obtained. Based on this, an expression containing the lifting force information of the workover rig hook is used to characterize the actual drilling pressure acting on the first structure. Then, combined with the ultimate bearing capacity of the titanium alloy pipe, the real-time lifting force of the workover rig hook is determined under the condition that the minimum drilling pressure required for the current drilling operation is met, and the actual drilling pressure acting on the first structure is at the ultimate bearing capacity of the titanium alloy pipe. The drilling pressure is then controlled by real-time adjustment of the (real-time) lifting force of the workover rig hook.

[0122] Specifically, by performing a force analysis on the titanium alloy tube 36 and the jet nozzle assembly, the force analysis results of the first structure are obtained, including at least the pulling force of the workover rig hook, the gravity of the tubing assembly, the viscous resistance of the fluid, and the steering resistance of the steering device 37. Using the frictional resistance characteristics of each section, the maximum axial force of each well section is determined. In this embodiment, the maximum axial force is divided into three parts: the axial force of the horizontal section is the frictional resistance of the horizontal section; the axial force of the steering section is the frictional resistance of the steering section; and the axial force of the vertical section is the gravity of the tubing assemblies with different wall thicknesses and the frictional resistance of the vertical section. Therefore, the maximum axial force required for horizontal drilling is the sum of the axial force of the vertical section tubing string gravity, the vertical section frictional resistance, the horizontal section frictional resistance, and the steering resistance of the curved section. The axial force of the horizontal section is obtained according to the aforementioned formulas (1), (3), (6), and (8); the axial force of the turning section is obtained using the aforementioned formula (13); and the axial force of the vertical section is obtained by calculating the frictional resistance of the vertical section using the aforementioned formula (25) and combining it with the gravity of the tubing assemblies with different wall thicknesses. Furthermore, the minimum drilling pressure is obtained by subtracting the lifting force T of the current workover rig hook from the gravity of the tubing assemblies with different wall thicknesses.

[0123] The maximum axial force in the vertical section is the maximum hook load. This maximum hook load is compared with the maximum hook load of the workover rig. If it is less than the maximum hook load of the workover rig, then the current workover rig has the capability to adjust the drilling pressure by lifting the tubing string assembly. Next, assuming the current workover rig has the capability to adjust the drilling pressure by lifting the tubing string assembly, the actual drilling pressure acting on the first structure is further compared with the current minimum drilling pressure. The real-time lifting force of the workover rig hook is used as an unknown quantity to characterize the actual drilling pressure acting on the first structure. Finally, considering the ultimate bearing capacity of the titanium alloy tubing 36, the real-time tensile force (real-time lifting force) of the current workover rig hook is calculated to control the drilling pressure by adjusting the lifting force of the workover rig hook.

[0124] Based on the above-described method for calculating the friction of tubing in constant-pressure radial hydraulic drilling, this invention also provides a tubing friction calculation system for constant-pressure radial hydraulic drilling (hereinafter referred to as the "tubing friction calculation system"). Figure 5 This is a block diagram of a tubing friction calculation system for constant pressure radial hydraulic drilling according to an embodiment of this application.

[0125] like Figure 5As shown, the tubing string friction calculation system in this embodiment of the invention includes: a tubing string assembly determination module 51, a friction calculation module 52, and a drilling pressure adjustment module 53. Specifically, the tubing string assembly determination module 51 is implemented according to the method described in step S110 above, configured to design a tubing string assembly that meets the current constant pressure radial hydraulic drilling requirements, and to use a workover rig to control the lifting and lowering of the tubing string assembly. The tubing string assembly includes tubing of different wall thicknesses, titanium alloy tubing, and jet nozzle drill bit assemblies. The friction calculation module 52 is implemented according to the method described in step S120 above, configured to calculate the friction resistance characteristics of the horizontal, turning, and vertical sections in the current tubing string assembly based on the structural and construction parameters of the tubing string assembly designed by the scheduling and management module 51. The drilling pressure adjustment module 53 is implemented according to the method described in step S130 above, configured to adjust the drilling pressure of the tubing string in real time based on the friction resistance characteristics of each section calculated by the friction calculation module 52, combined with the overall stress condition of the current tubing string assembly and the actual drilling characteristics.

[0126] Example 2

[0127] In one specific embodiment of this application, a life safety evaluation device for continuous tubes with grooved scratch defects (hereinafter referred to as "life safety evaluation device") is used as an example for detailed description.

[0128] In this embodiment, the life safety assessment device is installed inside the target well in the Tarim Oilfield. Based on field data from the Tarim Oilfield, the current target well depth is 6000m, requiring 50m of horizontal drilling. A tubing assembly as described in Embodiment 1 is designed, which, under the action of high-pressure fluid, performs jet rock breaking to achieve radial hydraulic drilling. A workover rig is used as the surface equipment to lift and lower the tubing assembly, thereby controlling and adjusting the current drilling pressure in real time.

[0129] Following the method described in Example 1, the current pipe column assembly is divided into horizontal, turning, and vertical sections, and corresponding frictional resistance calculation models are established for each. In this embodiment, the relevant parameters of the titanium alloy pipe are as follows: inner diameter 0.0214m, outer diameter 0.0254m, and absolute surface roughness 8×10⁻⁶. -5 m, wall thickness 0.002m, density 4470kg / m³ 3 Weight 1.15 kg / m, yield strength 654 MPa, bending stiffness 1215.8 N / m 2 The relevant parameters of the drilling fluid are as follows: density 1200 kg / m³ 3 Viscosity 1.005×10 -3 Pa·s, flow rate 0.005 m³ / s 3 / s. The relevant parameters of the jet nozzle are as follows: nozzle outlet diameter 0.005m, nozzle flow coefficient 0.56. In addition, the friction coefficient between the titanium alloy tube and the orifice wall is 0.3. Substituting the above relevant parameters and the on-site construction parameters into the horizontal section friction resistance calculation model, the friction resistance of the current target well horizontal section is found to be 14.6kN.

[0130] Furthermore, the radius of curvature of the steering gear is 0.2m, and the coefficient of friction between the titanium alloy tube and the track wall is 0.3. Substituting the corresponding parameters into the friction resistance calculation model of the steering section, the friction resistance of the steering section of the current target working well is found to be 4.74kN.

[0131] Preferably, the tubing assembly uses P110 casing with an inner diameter of 0.1937m. The relevant parameters of the P110 tubing are as follows: length 5000m, inner diameter 0.076m, outer diameter 0.0889m, and linear weight q113.11kg / m. The relevant parameters of the P110 weighted tubing are as follows: length 1000m, inner diameter 0.06986m, outer diameter 0.0889m, and linear weight q218.64kg / m. Additionally, the open hole diameter is 0.03m. Substituting the corresponding parameters into the vertical section friction resistance calculation model, the friction resistance of the current target well's turning section is obtained as 595kN (the friction resistance caused by the change in cross-section from the tubing to the titanium alloy tubing accounts for the largest proportion). Furthermore, the total weight of the tubing assemblies with different wall thicknesses is 825.06kN.

[0132] According to the method described in Example 1, through force analysis of the titanium alloy tubing and jet nozzle assembly, the force analysis results of the first structure, including at least the pulling force of the workover rig hook, the gravity of the tubing assembly, the viscous resistance of the fluid, and the steering resistance of the steering gear, are obtained. Based on the aforementioned friction resistance calculation results and force analysis results, the maximum axial force of the horizontal section is determined to be 12.6 kN, the maximum axial force in the steering gear is 4.81 kN, and the maximum axial force of the vertical section is recorded as the maximum hook load of 1440 kN. In this embodiment, the XJ750 workover rig is preferably used, which has a maximum hook load of 1700 kN, which is greater than the maximum hook load that can be lifted by the current tubing assembly. Therefore, the current workover rig has the ability to lift the tubing assembly to adjust the drilling pressure. Next, the minimum drilling pressure required for horizontal drilling of 50 m is calculated to be 18.9 kN, and the actual drilling pressure acting on the first structure of the titanium alloy tubing and jet nozzle assembly is (226-T) kN (where T is the lifting force of the workover rig hook). In this embodiment, the ultimate bearing capacity of the titanium alloy pipe is 56.58 kN. At this time, it is necessary to reasonably adjust the lifting force of the workover rig hook to control the drilling pressure while ensuring that the ultimate bearing capacity of the titanium alloy pipe is not exceeded.

[0133] This invention proposes a method and system for calculating tubing friction in constant-pressure radial hydraulic drilling. Based on high-pressure radial hydraulic drilling technology, this method and system employ unconventional sidetracking techniques to achieve high-efficiency production enhancement in high-temperature, high-pressure, and ultra-deep wells. It utilizes a combination of workover rigs and tubing for radial drilling, and simultaneously provides a corresponding tubing friction calculation method for this drilling technology, thereby promoting its application and providing guidance for practical field operations. This improves the recovery rate of high-temperature, high-pressure, and ultra-deep wells, increases their oil and gas production, and reduces construction costs.

[0134] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0135] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

[0136] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device, or fabricating them separately as individual integrated circuit modules, or fabricating multiple modules or steps as a single integrated circuit module. Thus, the present invention is not limited to any particular hardware and software combination.

[0137] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for calculating the frictional resistance of a tubing string in constant-pressure radial hydraulic drilling, characterized in that, include: The design meets the requirements of current constant pressure radial hydraulic drilling. The tubing assembly includes tubing of different wall thicknesses, titanium alloy tubing and jet nozzle drill bit assembly, and uses a workover rig to control the lifting and lowering of the tubing assembly. Based on the structural and construction parameters of the tubular assembly, the frictional resistance characteristics of the horizontal, turning, and vertical sections in the current tubular assembly are calculated respectively. The horizontal section of the tubing assembly includes a titanium alloy tubing and a jet nozzle drill bit assembly. The calculation of the frictional resistance characteristics of the horizontal section includes: calculating the friction coefficient of the drilling fluid in the turbulent flow within the titanium alloy tubing and the friction coefficient of the fluid in the annulus based on the structural and construction parameters of the titanium alloy tubing and jet nozzle drill bit assembly; further obtaining the frictional resistance of the fluid in the horizontal section and the frictional resistance of the fluid in the annulus; calculating the frictional resistance of the open hole wall to the titanium alloy tubing; and calculating the resistance acting on the jet drill bit based on the relationship between the nozzle displacement and the drill bit pressure drop. The calculation of the frictional resistance characteristics of the turning section includes: performing a force analysis on the turning section of the tubing assembly under normal stable radial drilling conditions and under conditions where the titanium alloy tubing is fully deformed within the turning device's internal slide; and determining the frictional resistance of the turning section by calculating the work done by external forces on the turning section during the process from no deformation to full deformation. The vertical section of the tubing assembly includes tubing, tubing couplings, weighted tubing, transition joints, and titanium alloy tubing. The calculation of the frictional resistance characteristics of the vertical section includes: calculating the frictional resistance of the fluid inside the tubing and the frictional resistance of the fluid in the annulus of the vertical section based on the structural and construction parameters of the vertical section; calculating the fluid pressure loss caused by tubing assemblies with different wall thicknesses and the pressure loss caused when fluid flows from the tubing into the titanium alloy tubing; and determining the total frictional resistance of the fluid in the current vertical section by summing all types of frictional resistance and all types of pressure loss. Based on the frictional resistance characteristics of each section, combined with the overall stress of the current tubing assembly and the actual drilling characteristics, the drilling pressure of the tubing is adjusted in real time.

2. The method according to claim 1, characterized in that, include: Based on the frictional resistance data of each section, the minimum drilling pressure for the current constant pressure radial hydraulic borehole and the actual drilling pressure acting on the first structure composed of titanium alloy pipe and jet nozzle are determined by analyzing the force on the current pipe string assembly. Based on the minimum drilling pressure and the actual drilling pressure acting on the first structure, it is determined whether the actual drilling pressure acting on the first structure is within the bearing capacity of the tubing string while meeting the minimum drilling pressure required for the current drilling, so as to adjust the drilling pressure that can be provided for the current tubing string combination in real time.

3. The method according to claim 2, characterized in that, Based on the frictional resistance data of each section, the maximum axial force of each well section is determined, and the lifting force of the workover rig hook, the weight of the tubing, the viscous resistance of the fluid, and the steering resistance of the steering gear are further obtained. Based on this, the actual drilling pressure acting on the first structure is characterized by an expression containing the lifting force information of the workover rig hook. Based on the ultimate bearing capacity of the titanium alloy pipe, the lifting force of the workover rig hook is determined under the condition that the minimum drilling pressure required for the current drilling is met and the actual drilling pressure acting on the first structure is at the ultimate bearing capacity of the titanium alloy pipe. The drilling pressure is controlled by adjusting the lifting force of the workover rig hook in real time.

4. The method according to claim 1, characterized in that, The frictional resistance of the horizontal segment can be calculated using the following expression: in, This represents the frictional resistance of the fluid within the horizontal section. The coefficient of friction representing the turbulent flow of drilling fluid inside a titanium alloy tube. This indicates the density of the drilling fluid. This indicates the flow rate of the fluid inside the titanium alloy tube. This indicates the lowering speed of the tubing assembly. Indicates the inner diameter of the titanium alloy tube. Indicates the length of the horizontal segment. This represents the frictional resistance of the fluid within the horizontal annulus. This represents the friction coefficient of the fluid inside the annulus of a titanium alloy tube. Indicates the outer diameter of the titanium alloy tube. This indicates the flow velocity of the fluid inside the annulus of the titanium alloy tube. F f1 This indicates the frictional resistance between the open-hole wellbore and the titanium alloy casing. μ t This represents the coefficient of friction between the titanium alloy tube and the hole wall. K t Indicates the buoyancy coefficient. w e This indicates the weight per meter of titanium alloy tubing. L t This indicates the length of the titanium alloy tube.

5. The method according to claim 1, characterized in that, The frictional resistance of the steering segment can be calculated using the following expression: in, This indicates the frictional resistance during the steering segment. This indicates that the turning section is subjected to the axial thrust of the upper vertical section. This indicates that the turning section is subjected to axial pressure from the lower horizontal section. This represents the frictional resistance of the track to the turning section. Indicates the yield strength of the titanium alloy tube. This indicates the outer radius of the titanium alloy tube's turning section. This indicates the wall thickness of the titanium alloy tube. This indicates the radius of curvature of the steering gear.

6. The method according to claim 1, characterized in that, The frictional resistance of the vertical segment can be calculated using the following expression: in, F g This represents the frictional resistance of the fluid within an oil pipe assembly with different wall thicknesses. f g It represents the coefficient of friction of drilling fluid in turbulent flow within tubing assemblies with different wall thicknesses. ρ This indicates the density of the drilling fluid. v i This indicates the flow velocity of the fluid inside the vertical section of the pipe. v This indicates the lowering speed of the tubing assembly. d g Indicates the inner diameter of the oil pipe. L g Indicates the length of the tubing assembly. F v This represents the frictional resistance of the fluid within the vertical annulus. f v This represents the friction coefficient of the fluid within the vertical annulus. This indicates the flow velocity of the fluid within the vertical annulus. D h Indicates the inner diameter of the steering gear sleeve. D g Indicates the outer diameter of the oil pipe. F Δ represents the total frictional resistance of the fluid in the current vertical segment. p g-g This indicates the fluid pressure loss caused by combinations of oil pipes with different wall thicknesses. Δ represents the difference in cross-sectional area between tubing assemblies with different wall thicknesses. p s This indicates the fluid pressure loss caused by the fluid flowing from the weighted oil pipe into the titanium alloy pipe. This indicates the difference in cross-sectional area between the weighted oil pipe and the titanium alloy pipe.

7. A system for calculating the frictional resistance of a tubing string in constant-pressure radial hydraulic drilling, characterized in that, The system includes the following modules: The tubing assembly determination module is used to design tubing assemblies that meet the requirements of current constant pressure radial hydraulic drilling, and to control the lifting and lowering of the tubing assembly using a workover rig. The tubing assembly includes tubing of different wall thicknesses, titanium alloy tubing, and jet nozzle drill bit assemblies. The friction resistance calculation module is used to calculate the friction resistance characteristics of the horizontal, turning, and vertical sections of the tubing assembly based on the structural and construction parameters of the tubing assembly. The horizontal section of the tubing assembly includes a titanium alloy tube and a jet nozzle drill bit assembly. The calculation of the horizontal section's friction resistance characteristics includes: calculating the friction coefficient of the drilling fluid flowing turbulently within the titanium alloy tube and the friction coefficient of the fluid in the annulus based on the structural and construction parameters of the titanium alloy tube and jet nozzle drill bit assembly; further obtaining the friction resistance of the fluid in the horizontal section and the friction resistance of the fluid in the annulus; calculating the friction resistance of the open hole wall against the titanium alloy tube; and calculating the resistance acting on the jet drill bit based on the relationship between the nozzle displacement and the drill bit pressure drop. The calculation of the turning section's friction resistance characteristics includes: performing a force analysis on the turning section of the tubing assembly under normal stable radial drilling conditions and under conditions where the titanium alloy tube is fully deformed within the turning device's internal slide; and determining the friction resistance of the turning section by calculating the work done by external forces on the turning section during the process from no deformation to full deformation. The vertical section of the tubing assembly includes tubing, tubing couplings, weighted tubing, transition joints, and titanium alloy tubing. The calculation of the frictional resistance characteristics of the vertical section includes: calculating the frictional resistance of the fluid inside the tubing and the frictional resistance of the fluid in the annulus of the vertical section based on the structural and construction parameters of the vertical section; calculating the fluid pressure loss caused by tubing assemblies with different wall thicknesses and the pressure loss caused when fluid flows from the tubing into the titanium alloy tubing; and determining the total frictional resistance of the fluid in the current vertical section by summing all types of frictional resistance and all types of pressure loss. The drilling pressure adjustment module is used to adjust the drilling pressure of the tubing string in real time based on the friction resistance characteristics of each section, combined with the overall stress situation of the current tubing string assembly and the actual drilling characteristics.

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