A method and system for evaluating dynamic drilling trends for bent-slug drill assemblies

Abstract

The application provides a method and system for evaluating the dynamic drilling trend of a bent-slug drill assembly, which comprises the following steps: determining a straight beam drill assembly for realizing the drilling effect based on the corresponding equivalent principle of the target bent-slug drill assembly design through an equivalent setting step; obtaining the dynamic model of the straight beam drill assembly through the discrete processing and comprehensive processing of the set of factors of the drill string stiffness, the drill string mass, the drill string damping and the equivalent load; calculating the displacement vector of each drill string unit; and correcting the equivalent load vector by using a setting strategy until the displacement vector of the same constraint node meets the setting condition; and finally solving the dynamic model of the drill string to obtain the dynamic lateral force of the drill bit and the dynamic rotation angle of the drill bit, and establishing a drilling trend angle calculation model by comprehensively considering the cutting index of the drill bit. The above scheme takes into account the influence of multiple factors on the drilling trend, is suitable for long build-up sections and horizontal sections, and can effectively guide the optimization of the drill assembly, the optimization of the drilling parameters such as the drilling pressure and the rotation speed.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling optimization technology, and in particular to a method and system for evaluating the dynamic drilling trend of bent screw drill string combinations. Background Technology

[0002] As the difficulty of oil and gas reservoir extraction in the oil and gas development field increases, the demand for highly deviated wells and horizontal wells is growing. Rotary steerable drilling technology has advantages such as low frictional torque, strong displacement extension capability, and smooth and easily controllable wellbore trajectory. It has good technical advantages in drilling long stable-angle sections of highly deviated wells and horizontal sections of horizontal wells. However, its structure is complex, its manufacturing cost is high, and the cost of on-site tooling services is expensive. In contrast, drill string assemblies with bent screws are a simple and low-cost way to achieve long stable-angle and horizontal sections. The structural feature of bent screws is that the screw shell is bent. According to the wellbore trajectory control requirements, bent screws usually have different bending angles and are combined with centralizers, drill collars, etc. to form bent screw drill string assemblies. In the combined drilling of stable-angle and horizontal sections, single bent screw drill string assemblies with small angles are often used to ensure stable drilling of the drill string assembly.

[0003] The researchers of this invention considered that the drilling trend of the bent screw drill string assembly often changes significantly under different drilling pressure and rotational speed conditions during use. When the well inclination changes significantly, a sliding directional drilling method is required to meet the well trajectory control requirements in order to ensure the quality of the wellbore trajectory. However, as the horizontal well section lengthens, the frictional resistance of the drill string increases sharply, resulting in low sliding directional drilling efficiency, which seriously affects the mechanical drilling rate and the economic benefits of drilling. Therefore, the researchers of this invention believe that it is necessary to develop a complete and reasonable dynamic drilling trend prediction system for bent screw drill string assemblies to clarify the influence of factors such as drill string assembly, drilling pressure, and rotational speed on the drilling trend of bent screw drill string assemblies. This will have significant positive implications for achieving the goal of efficient and stable inclination drilling operations using bent screw drill string assemblies.

[0004] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a method and system for evaluating the dynamic drilling trend of a bent screw drill assembly. This method predicts and evaluates the wellbore inclination change trend of the bent screw drill assembly during composite drilling in long, stable inclination sections and horizontal sections. It clarifies the influence of factors such as drill assembly, drilling pressure, and rotational speed on the drilling trend of the bent screw drill assembly, thereby guiding the optimization of the drill assembly and the selection of drilling parameters such as drilling pressure and rotational speed. This reduces the fluctuation of the wellbore trajectory, lowers the directional frequency, increases the proportion of composite drilling, and ultimately improves the mechanical drilling rate, achieving the operational goal of efficient and stable inclination drilling of the bent screw drill assembly in long, stable inclination sections and horizontal sections.

[0006] Specifically, in one embodiment, the method includes:

[0007] The equivalent setting steps involve analyzing the structural characteristics and operating principle of the target bent screw drill assembly to design the corresponding equivalent principles. Based on these equivalent principles, a straight beam drill assembly that can accurately replace the target bent screw drill assembly to achieve the expected drilling effect is determined as the equivalent evaluation drill assembly.

[0008] After discretizing the equivalent evaluation drill string assembly, the dynamic model is established by deriving the dynamic control equation of the drill string unit based on the variational principle of dynamic problems. Then, the dynamic model of the overall drill string assembly is obtained by integrating the drill string stiffness factor, drill string mass factor, drill string damping factor and equivalent load factor.

[0009] The calculation optimization steps include solving the equivalent evaluation of the dynamic model of the drill string assembly, calculating the displacement vector of the drill string unit, and correcting the equivalent load vector based on it until the displacement vector of the same drill string unit node satisfies the set conditions.

[0010] The evaluation model is constructed by using the dynamic model of the drill string in the equivalent evaluation drill string assembly to solve for the dynamic lateral force and dynamic rotation angle of the drill bit. The drilling trend angle calculation model of the equivalent evaluation drill string assembly is established by comprehensively considering the drill bit cutting index, so as to evaluate the dynamic drilling trend of the target bent screw drill string assembly.

[0011] Furthermore, in one embodiment, the equivalent setup step includes the following operations:

[0012] The equivalent position of applying concentrated load in the equivalent evaluation drill string assembly is analyzed so that the equivalent evaluation drill string assembly after the concentrated load is applied can accurately reflect the stress state of the bending angle of the target bent screw drill string assembly.

[0013] Mechanical models of the target bent screw drill assembly and mechanical models of the drill assembly after applying load at the target equivalent position are established respectively. Based on the established models, the bending moment at the bend and the bending moment at the equivalent position are calculated respectively. Then, the equivalent concentrated load value to be applied is determined based on the calculation results.

[0014] Based on the principle that the sum of the centrifugal forces generated by the drill bits on both sides of the bend is equal to the centrifugal force generated by the equivalent mass eccentricity of the equivalent evaluation drill bit assembly, the equivalent mass eccentricity of the equivalent evaluation drill bit assembly is derived.

[0015] In a preferred embodiment, in the equivalent setup step, based on the location of the bend in the bent screw drill assembly, the same location is selected in the equivalent replacement straight beam drill assembly as the target equivalent location for applying the lateral concentrated load. In one embodiment, the equivalent setup step includes:

[0016] The mechanical model of the target bent screw drill assembly is established using the longitudinal and transverse bending beam method, and the bending moment at the bend is determined. After applying the first concentrated load at the target equivalent position, the mechanical model of the equivalent evaluation drill assembly is established using the longitudinal and transverse bending beam method, and the bending moment at the equivalent position is calculated. If they are not equal, the applied load value is adjusted to the second concentrated load, the mechanical model is re-established, and the bending moment at the equivalent position is calculated until the two bending moments are equal. The currently applied load value is taken as the target equivalent load value.

[0017] Furthermore, in one embodiment, in the dynamic model establishment step, the drill string assembly is discretized using spatial beam elements, and the dynamic control equations of the drill string elements are derived based on the variational principle of dynamic problems. The overall drill string stiffness matrix, mass matrix, damping matrix, and equivalent load vector are then obtained by further assembling them.

[0018] Specifically, in one embodiment, the computation optimization step includes:

[0019] Step A1: Calculate the displacement vector of the drill string element using the Newmark numerical solution method, and determine the contact state between the drill string and the wellbore based on the calculated drill string element position vector and the wellbore clearance.

[0020] Step A2: Combine the results of the integrated contact state judgment with the equivalent load vector corrected for the wellbore contact deformation;

[0021] Step A3: After correcting the equivalent load vector, calculate the displacement vector of the drill string element using the Newmark numerical solution method, and proceed to step A4;

[0022] Step A4: Determine whether the node numbers of the constraint points are consistent. If they are consistent, further analyze whether the contact deformation deviation is within the allowable error range. If the contact deformation deviation is within the allowable error range, save the current node displacement, velocity, and acceleration vectors and go to step A1. Otherwise, go to step A5.

[0023] Step A5: Return to step A1 and repeat until both conditions are met simultaneously.

[0024] Furthermore, in the computation optimization step, for a new time step, steps A1 to A5 are repeated and the computation is terminated when the time step meets the predetermined time length.

[0025] Furthermore, in an optional embodiment, the method further includes:

[0026] An evaluation data list is pre-created, which stores data on different drill bit combinations, drilling pressure and rotation speed for bent screw drill bit combinations. It also stores corresponding drill bit lateral force, drill bit dynamic rotation angle and drill bit cutting data for equivalent evaluation drill bit combinations.

[0027] During the evaluation, the parameters of the drilling trend angle calculation model are set according to the drill bit lateral force, drill bit dynamic rotation angle and drill bit cutting data. The drilling state parameters to be tested are input, and the evaluation results are obtained by analyzing the trend angle data output by the model.

[0028] Based on the method for evaluating the dynamic drilling trend of the bent screw drill assembly as described in any one or more of the above embodiments, the present invention also provides a storage medium storing program code that can implement the method as described in any one or more of the above embodiments.

[0029] Based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a system for evaluating the dynamic drilling trend of a bent screw drill assembly, the system performing the methods described in any one or more of the above embodiments.

[0030] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0031] This invention provides a method and system for evaluating the dynamic drilling trend of a bent screw drill assembly. The method replaces the bent screw drill assembly with a straight beam drill assembly by applying a lateral concentrated load, thereby realizing the calculation and analysis of the mechanical properties of the bent screw drill assembly. It ensures the accuracy of the evaluation calculation while controlling the computational complexity and scale, making it easy to promote.

[0032] Furthermore, the method of this invention comprehensively considers the drilling trend angle calculation model of the drill string assembly, which takes into account the influence of drill bit lateral force, drill bit rotation angle, and drill bit cutting anisotropy index. The drilling trend evaluation method considers more comprehensive factors and can more accurately understand the well inclination change trend during composite drilling of bent screw drill string assemblies, as well as the influence of factors such as drill string assembly, drilling pressure, and rotation speed on the drilling trend of drill string assemblies. It can effectively reduce the fluctuation of wellbore trajectory, reduce directional frequency, increase the proportion of composite drilling, and thus increase mechanical drilling speed. This provides theoretical guidance for achieving the operational goal of efficient and stable inclination drilling of bent screw drill string assemblies in long stable inclination sections and horizontal sections.

[0033] 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

[0034] 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:

[0035] Figure 1 This is a flowchart illustrating a method for evaluating the dynamic drilling trend of a bent screw drill assembly according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the bent screw drill assembly structure provided in an embodiment of the present invention;

[0037] Figure 3 This is a flowchart illustrating a method for evaluating the dynamic drilling trend of a bent screw drill assembly according to an embodiment of the present invention.

[0038] Figure 4 This is a diagram illustrating the variation of the well inclination trend angle with the outer diameter of the screw stabilizer in a method for evaluating the dynamic drilling trend of a bent screw drill assembly, provided by another embodiment of the present invention.

[0039] Figure 5 This is a diagram illustrating the variation of the well inclination trend angle with the outer diameter of the upper stabilizer in the method for evaluating the dynamic drilling trend of the bent screw drill assembly provided in this embodiment of the invention.

[0040] Figure 6 This is a flowchart illustrating a method for evaluating the dynamic drilling trend of a bent screw drill assembly according to another embodiment of the present invention.

[0041] Figure 7 This is a schematic diagram of the system for evaluating the dynamic drilling trend of a bent screw drill assembly, provided in an embodiment of the present invention. Detailed Implementation

[0042] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Those skilled in the art will then fully understand how the present invention uses technical means to solve technical problems and achieve technical effects, and will be able to implement the present invention specifically based on the above-described implementation process. It should be noted that, as long as there is no conflict, the various embodiments and features 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.

[0043] Although the flowchart describes the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can terminate when its operation is complete, but it may also have additional steps not included in the diagram. A process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0044] Computer equipment includes user equipment and network equipment. User equipment or clients include, but are not limited to, computers, smartphones, PDAs, etc.; network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing consisting of a large number of computers or network servers. Computer equipment can operate independently to implement this invention, or it can connect to a network and implement this invention through interaction with other computer equipment in the network. The network in which the computer equipment is located includes, but is not limited to, the Internet, wide area network, metropolitan area network, local area network, VPN network, etc.

[0045] The terms “first,” “second,” etc., may be used herein to describe various units, but these units should not be limited by these terms; they are used merely to distinguish one unit from another. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. When a unit is referred to as “connected” or “coupled” to another unit, it may be directly connected or coupled to said other unit, or there may be intermediate units present.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0047] Drill string assemblies with bent screws are a simple and cost-effective method for achieving long, stable, and horizontal drilling sections. The structural feature of the bent screw is its curved screw housing. Depending on the wellbore trajectory control requirements, the bent screw typically has different bending angles and is combined with stabilizers, drill collars, etc., to form a bent screw drill string assembly. In combined drilling of stable and horizontal sections, single-bent screw drill string assemblies with small angles are often used to ensure stable drilling.

[0048] The researchers of this invention considered that the drilling trend of the bent screw drill string assembly often changes significantly under different drilling pressure and rotational speed conditions during use. When the well inclination changes significantly, a sliding directional drilling method is required to meet the well trajectory control requirements in order to ensure the quality of the wellbore trajectory. However, as the horizontal well section lengthens, the frictional resistance of the drill string increases sharply, resulting in low sliding directional drilling efficiency, which seriously affects the mechanical drilling rate and the economic benefits of drilling. Therefore, the researchers of this invention believe that it is necessary to develop a complete and reasonable dynamic drilling trend prediction system for bent screw drill string assemblies to clarify the influence of factors such as drill string assembly, drilling pressure, and rotational speed on the drilling trend of bent screw drill string assemblies. This will have significant positive implications for achieving the goal of efficient and stable inclination drilling operations using bent screw drill string assemblies.

[0049] In existing technologies, some scholars have conducted drilling trend prediction for drill string assemblies with bends. They have established a mechanical model of a single-bend screw drill string using the longitudinal and transverse bending method. Starting from the influence of parameters such as screw bend angle, wellbore curvature, drilling pressure, and stabilizer diameter, they have analyzed the static relationship between the lateral force and the ultimate build-up rate of the single-bend screw drill string assembly. Although this method can predict the static build-up capacity of the single-bend screw drill string assembly in the build-up section to a certain extent, its applicability is limited. It cannot achieve accurate dynamic prediction of the drilling trend of the bent screw drill string assembly, and it cannot effectively predict the drilling capacity or trend when the well involves horizontal sections.

[0050] To address the aforementioned issues, this invention provides a method and system for evaluating the dynamic drilling trend of a bent screw drill assembly. Considering the special structure and mechanical principles of the bent screw drill assembly, directly constructing a computational model is difficult and the computational accuracy is hard to control. The researchers of this invention use equivalent lateral concentrated loads and equivalent mass eccentricity applied to the straight beam drill assembly to perform equivalent processing on the bent screw drill assembly, which more accurately reflects the stress and deformation characteristics of the bent screw drill assembly.

[0051] Based on the equivalent straight beam drill string assembly, and considering the influence of drill bit lateral force, drill bit rotation angle, and drill bit cutting anisotropy index on the drilling trend of the drill string assembly, an evaluation model for the well inclination change trend during composite drilling with bent screw drill string assembly was established. Using the well inclination trend angle as the evaluation index, a qualitative evaluation of the well inclination change law of bent screw drill string assembly and the influence of factors such as drill string assembly, drilling pressure, and rotation speed on the drilling trend of the drill string assembly were realized.

[0052] The method described in this invention can guide the optimization of drill string assembly and the selection of drilling parameters, providing theoretical guidance for achieving the operational goal of efficient and stable angle drilling of curved screw drill string assemblies in long and stable angled sections and horizontal sections.

[0053] The following describes the detailed flow of the method according to an embodiment of the present invention with reference to the accompanying drawings, the steps of which can be executed in a computer system containing, for example, a set of computer-executable instructions. Although the logical order of the steps is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0054] Example 1

[0055] Figure 1 This diagram illustrates a flowchart of a method for evaluating the dynamic drilling trend of a bent screw drill assembly according to Embodiment 1 of the present invention. (Refer to...) Figure 1 As can be seen, the method includes the following steps.

[0056] The equivalent setting step S110 involves analyzing the structural characteristics and operating principle of the target bent screw drill assembly to design the corresponding equivalent principle, and based on the equivalent principle, determining the straight beam drill assembly that can accurately replace the target bent screw drill assembly to achieve the expected drilling effect, as the equivalent evaluation drill assembly.

[0057] In step S120 of establishing the dynamic model, after discretizing the equivalent evaluation drill string assembly, the dynamic control equation of the drill string unit is derived according to the variational principle of dynamic problems. Then, the dynamic model of the overall drill string assembly is obtained by integrating the drill string stiffness factor, drill string mass factor, drill string damping factor and equivalent load factor.

[0058] In the calculation optimization step S130, the dynamic model of the equivalent evaluation drill string assembly is solved to calculate the displacement vector of the drill string unit, and the equivalent load vector is corrected based on it until the displacement vector of the same drill string unit node satisfies the set conditions.

[0059] The evaluation model construction step S140 involves using the dynamic model of the drill string in the equivalent evaluation drill string assembly to solve for the dynamic lateral force and dynamic rotation angle of the drill bit. A drilling trend angle calculation model for the equivalent evaluation drill string assembly is established by comprehensively considering the drill bit cutting index, so as to evaluate the dynamic drilling trend of the target bent screw drill string assembly.

[0060] Because the curved drill string assembly deforms due to the constraint of the wellbore wall, its stress and deformation state differs from that of the straight beam drill string assembly. The structural diagram of the curved screw drill string assembly is shown below. Figure 2 As shown. In order for the straight beam drill assembly, which serves as the equivalent evaluation drill assembly, to reliably and equivalently represent the stress and deformation state of the bent screw drill assembly to be evaluated, it is necessary to design the equivalent bending angle data of the equivalent evaluation drill assembly from multiple aspects.

[0061] Therefore, in one embodiment, the equivalent setting step S110 includes the following operations:

[0062] (1) Analyze the equivalent position of applying concentrated load in the equivalent evaluation drill string assembly so that the equivalent evaluation drill string assembly after the concentrated load is applied can accurately reflect the stress state of the bending angle of the target bent screw drill string assembly.

[0063] (2) Establish a mechanical model of the target bent screw drill assembly and a mechanical model of the drill assembly after applying load at the target equivalent position. Calculate the bending moment at the bend and the bending moment at the equivalent position based on the established models. Then, decide the equivalent concentrated load value to be applied based on the calculation results.

[0064] (3) Based on the principle that the sum of the centrifugal forces formed by the drill bits on both sides of the bend is equal to the centrifugal force formed by the equivalent mass eccentricity of the equivalent evaluation drill bit assembly, the equivalent mass eccentricity of the equivalent evaluation drill bit assembly is derived.

[0065] Specifically, according to the appendix Figure 3 According to the detailed execution information disclosed, in one embodiment, during the equivalent setup step, the equivalent position of the concentrated load applied in the equivalent evaluation drill string assembly is analyzed through the following operations to achieve the equivalent design of the bending angle of the straight beam drill string assembly:

[0066] Based on the location of the bend in the bent screw drill assembly, the same location is selected in the equivalent straight beam drill assembly as the target equivalent location for applying the lateral concentrated load; usually, the location of the applied load remains unchanged during the analysis and evaluation process.

[0067] In practical applications, the bent screw drill assembly is replaced by a straight beam drill assembly, while a lateral concentrated load Q is applied at the same location as the original bend. According to the principle of equivalence, when the bending moment at the concentrated load is equal to the bending moment generated by the original bent screw drill assembly at the bend, the stress state of the original bent screw drill assembly can be equivalently replaced by this lateral concentrated load acting on the straight beam drill assembly.

[0068] Furthermore, in one embodiment, the equivalent setup step, for operation (2), includes:

[0069] The mechanical model of the target bent screw drill assembly is established using the longitudinal and transverse bending beam method, and the bending moment at the bend is determined. After applying the first concentrated load at the target equivalent position, the mechanical model of the equivalent evaluation drill assembly is established using the longitudinal and transverse bending beam method, and the bending moment at the equivalent position is calculated. If they are not equal, the applied load value is adjusted to the second concentrated load, the mechanical model is re-established, and the bending moment at the equivalent position is calculated until the two bending moments are equal. The currently applied load value is taken as the target equivalent load value.

[0070] In practical applications, the longitudinal and transverse bending beam method can be used to establish mechanical models of bent screw drill string assemblies and straight beam drill string assemblies under transverse concentrated loads, respectively. The three-moment equation system for the two types of drill string assemblies can be established and solved to obtain the bending moments at the bending point and the point of application of the transverse concentrated load. The transverse concentrated load is changed until the bending moment value at the point of application of the load is the same as the bending moment value at the bending point of the bent screw drill string assembly. At this time, the transverse concentrated load is the equivalent transverse concentrated load of the bending angle, which is used as the target equivalent load value.

[0071] Furthermore, the axis of the bent screw drill assembly is not aligned with the wellbore axis. When the drill assembly rotates, the mass eccentricity caused by the bend causes centrifugal force. Therefore, in one embodiment, for operation (3), specifically, it includes: assuming the equivalent mass eccentricity of the bent screw drill assembly is r. e Based on the fact that the sum of the centrifugal forces formed by the drill bits on both sides of the bend is equal to the centrifugal force formed by the equivalent mass eccentricity of the straight beam drill bit assembly, the equivalent mass eccentricity of the straight beam drill bit assembly is derived.

[0072] After determining the straight beam drill string assembly that can equivalently replace the bent screw drill string assembly, a dynamic model of the equivalent straight beam drill string assembly is further established. Specifically, in one embodiment, in the dynamic model establishment step, the drill string assembly is discretized using spatial beam elements, and the dynamic control equations of the drill string elements are derived based on the variational principle of dynamic problems. The overall drill string stiffness matrix, mass matrix, damping matrix, and equivalent load vector are then obtained by combining them.

[0073] Furthermore, the dynamic model of the equivalent straight beam drill string assembly is solved according to a specific strategy. In the solution process, firstly, under the condition that it is uncertain whether the drill string is in contact with the well wall, the displacement of the drill string unit node is obtained by solving the equation using the Newmark method. Considering that the external force on the drill string includes contact constraint force, this constraint force will limit the drill string from further penetrating into the well wall. When the drill string is not in contact with the well wall, there is no constraint force from the well wall on the drill string in the external force on the drill string. At this time, the calculated lateral displacement of the drill string node may exceed the well wall range. Based on this, it is necessary to compare the displacement of the drill string unit node with the size of the wellbore clearance to determine whether the drill string unit node is in contact with the well wall and is subject to the constraint force of the well wall.

[0074] If the displacement u of a node in a drill string element r If the wellbore clearance is δ, then the drill string unit nodes should be in contact with the wellbore wall, at which point the drill string is subject to a constraint force F from the wellbore wall. n Further calculations should be performed according to the established strategy to calculate the force F exerted by the wellbore on the drill string. n And correct the state of the applied force;

[0075] After correcting the stress conditions of the drill string, the Newmark method is used to recalculate the displacement of the drill string element nodes a second time. This second displacement result will differ from the first calculation because the calculated constraint force is applied to the drill string. Based on this, it is determined again whether the current displacement of the drill string element nodes exceeds the wellbore clearance. If it does, the constraint force needs to be corrected again.

[0076] Repeat the above steps until the current drill string unit node displacement does not exceed the wellbore clearance, and the difference between the drill string unit displacement results obtained from the two calculations is within the allowable error range. Then, terminate the calculation to obtain the corrected drill string force equivalent load condition.

[0077] It should be noted that the above content only describes the judgment state of one node in the drill string unit. However, the drill string is often divided into many units, which means there are many nodes. Each node needs to be analyzed separately as described above. In addition, during actual analysis, when the drill string node comes into contact with the well wall, radial, tangential, and axial forces are generated. Since the formulas are numerous, they are simplified to the above formula for a resultant force.

[0078] Therefore, in one embodiment, the drill string element displacement vector is calculated using the Newmark numerical solution method; based on the wellbore contact deformation, the radial constraint force, tangential resistance, axial resistance, and friction torque of the drill string are calculated to correct the equivalent load vector; the drill string element displacement vector is calculated again using the Newmark numerical solution method to determine whether the current drill string element node (i.e., constraint point node number) is consistent and whether the contact deformation deviation is within the allowable error range. If both conditions are met, the node displacement, velocity, and acceleration vectors are saved. If the conditions are not met, the first two steps are repeated until the conditions are met. In actual calculations, the deviation of the contact deformation can be represented by the difference in the drill string element displacement vectors at the same node.

[0079] Specifically, in a preferred embodiment, the computation optimization step includes:

[0080] Step A1: Calculate the drill string element displacement vector using the Newmark numerical solution method, and determine the contact state between the drill string and the wellbore based on the calculated drill string element position vector and the wellbore clearance. Proceed to Step A2.

[0081] Step A2: Based on the comprehensive contact state judgment results and the corrected equivalent load vector of well wall contact deformation, proceed to step A3;

[0082] Step A3: After correcting the equivalent load vector, calculate the displacement vector of the drill string element using the Newmark numerical solution method, and proceed to step A4;

[0083] Step A4: Determine whether the node numbers of the constraint points are consistent. If they are consistent, further analyze whether the contact deformation deviation is within the allowable error range. If the contact deformation deviation is within the allowable error range, save the current node displacement, velocity, and acceleration vectors and go to step A1. Otherwise, go to step A5.

[0084] Step A5: Return to step A1 and repeat until both conditions are met simultaneously.

[0085] Furthermore, in the computation optimization step, for a new time step, steps A1 to A5 are repeated and the computation is terminated when the time step meets the predetermined time length.

[0086] Specifically, the force generated by the contact between the drill string unit node and the wellbore is calculated using the following formula:

[0087]

[0088] In the formula, F n For contact force, k c The contact stiffness between the drill string and the wellbore is given by Δ = u. r -δ represents the wellbore deformation. Where Δ<0 indicates that the drill string node is not in contact with the wellbore, and Δ≥0 indicates that the drill string node is in contact with the wellbore. The value of the equivalent load vector is then corrected based on the force calculation result, for example, by vectorizing the force and summing it with the current equivalent load vector.

[0089] In another optional embodiment, in order to correct the applied concentrated load based on the force condition of the accurate dynamic model during the actual application solution, the radial constraint force, tangential resistance, axial resistance and friction torque of the drill string can be calculated as correction parameters based on the contact deformation of the well wall to correct the equivalent load vector.

[0090] Specifically, in the process of calculating the drilling trend angle of the drill string assembly, a drilling trend angle calculation model is used to evaluate the drilling trend of the bent screw drill string assembly under different drill string assemblies and drilling parameter conditions. The drilling trend angle calculation model is established by solving the drill string dynamics analysis model to obtain the dynamic lateral force and dynamic rotation angle of the drill bit, and then considering the influence of drill bit anisotropy. This model can comprehensively consider the influence of drill bit lateral force, drill bit rotation angle, and drill bit cutting anisotropy index.

[0091] The proposed method for evaluating the drilling trend of bent screw drill string assemblies replaces the bent screw drill string assembly with a lateral concentrated load applied to a straight beam drill string assembly. This enables the calculation and analysis of the mechanical properties of the bent screw drill string assembly. The method comprehensively considers the influence of drill bit lateral force, drill bit rotation angle, and drill bit cutting anisotropy index in the calculation model of the drilling trend angle of the drill string assembly. This drilling trend evaluation method considers more comprehensive factors and can accurately identify the well inclination change trend during combined drilling with bent screw drill string assemblies, as well as the influence of factors such as drill string assembly, drilling pressure, and rotation speed on the drilling trend. This provides theoretical guidance for achieving the operational goal of efficient and stable inclination drilling with bent screw drill string assemblies in long, stable inclination sections and horizontal sections. Furthermore, it has a wide range of applications, not only suitable for stable inclination sections of highly deviated wells but also for drilling trend analysis in horizontal sections of horizontal wells, making it more practical.

[0092] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0093] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The specific steps are as follows:

[0094] (1) Equivalent treatment of bends.

[0095] Assemble the bent screw drill bit as follows Figure 1 A straight beam drill string assembly is used as a substitute, and a lateral concentrated load Q is applied at the same location as the original bend. According to the principle of equivalence, when the bending moment at the concentrated load point is equal to the bending moment generated by the original bent screw drill string assembly at the bend, the stress state of the original bent screw drill string assembly can be equivalently replaced by this lateral concentrated load acting on the straight beam drill string assembly.

[0096] (2) Calculation of equivalent transverse load.

[0097] The longitudinal and transverse bending beam method is used to establish mechanical models of bent screw drill string assembly and straight beam drill string assembly under transverse concentrated load, respectively. The three-moment equation system for the two types of drill string assemblies is established and solved to obtain the bending moments at the bending point and the point of application of the transverse concentrated load. The transverse concentrated load is changed until the bending moment value at the load application point is the same as the bending moment value at the bending point of the bent screw drill string assembly. At this time, the transverse concentrated load is the equivalent transverse concentrated load of the bending angle.

[0098] (3) Calculation of equivalent mass eccentricity.

[0099] The axis of the bent screw drill string assembly is not aligned with the wellbore axis. When the assembly rotates, the mass eccentricity caused by the bend induces centrifugal force. Assuming the equivalent mass eccentricity of the bent screw drill string assembly is re, the equivalent mass eccentricity of the straight beam drill string assembly can be derived based on the fact that the sum of the centrifugal forces generated by the drill strings on both sides of the bend is equal to the centrifugal force generated by the equivalent mass eccentricity of the straight beam drill string assembly.

[0100] (4) Establishment of the equivalent straight beam drill string combination dynamic model.

[0101] Spatial beam elements are used to discretize the drill string assembly. Based on the variational principle of dynamic problems, the dynamic control equations of the drill string elements are derived. The overall drill string stiffness matrix, mass matrix, damping matrix, and equivalent load vector are then obtained by combining the elements.

[0102] (5) Solution of the equivalent straight beam drill string combination dynamic model.

[0103] The drill string element displacement vector is calculated using the Newmark numerical solution method. Based on the wellbore contact deformation, the radial constraint force, tangential resistance, axial resistance, and frictional torque of the drill string are calculated to correct the equivalent load vector. The drill string element displacement vector is then calculated again using the Newmark numerical solution method to determine whether the constraint point node numbers are consistent and whether the contact deformation deviation is within the allowable error range. If both conditions are met, the node displacement, velocity, and acceleration vectors are saved. If the conditions are not met, the first two steps are repeated until the conditions are met. For a new time step, the first three steps are repeated, and the calculation terminates when the time step reaches the predetermined duration.

[0104] (6) Calculation of drilling trend angle of drill string assembly.

[0105] The dynamic lateral force and dynamic rotation angle of the drill bit are obtained by using a drill string dynamics analysis model. Considering the influence of drill bit anisotropy, a drilling trend angle calculation model for drill string assemblies is established, comprehensively considering the influence of drill bit lateral force, drill bit rotation angle, and drill bit cutting anisotropy index. This model aims to evaluate the drilling trend of drill string assemblies with bends under different drill string assemblies and drilling parameters. The influence laws of drill string assemblies and drilling parameters on the drilling trend of bent screw drill string assemblies are as follows: Figure 4 , Figure 5 As shown.

[0106] Specifically, in one embodiment, the target drill bit drilling trend angle is calculated according to the following mathematical model:

[0107]

[0108] In the formula, A P For drilling trend angle; F y F represents the dynamic lateral force of the drill bit. xFor drilling pressure; I b Let be the data volume of various drill bit indices; α be the dynamic rotation angle of the drill bit. Substituting the results of the drill string dynamics model into the above formula, the dynamic well inclination trend angle of the drill string assembly can be obtained.

[0109] It should be noted that, in other embodiments of the present invention, the method can also combine one or more of the above embodiments to obtain a new method for evaluating the dynamic drilling trend of the bent screw drill assembly, so as to realize the dynamic drilling situation analysis of the bent screw drill assembly.

[0110] It should be noted that, based on the methods in any one or more embodiments of the present invention described above, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more embodiments, and when the code is executed by the operating system, it can implement the method for evaluating the dynamic drilling trend of the bent screw drill assembly as described above.

[0111] Example 2

[0112] Figure 6 This diagram illustrates a flowchart of a method for evaluating the dynamic drilling trend of a bent screw drill assembly according to Embodiment 2 of the present invention. (Refer to...) Figure 6 As can be seen, the method includes the following steps.

[0113] The equivalent setting step S110 involves analyzing the structural characteristics and operating principle of the target bent screw drill assembly to design the corresponding equivalent principle, and based on the equivalent principle, determining the straight beam drill assembly that can accurately replace the target bent screw drill assembly to achieve the expected drilling effect, as the equivalent evaluation drill assembly.

[0114] In step S120 of establishing the dynamic model, after discretizing the equivalent evaluation drill string assembly, the dynamic control equation of the drill string unit is derived according to the variational principle of dynamic problems. Then, the dynamic model of the overall drill string assembly is obtained by integrating the drill string stiffness factor, drill string mass factor, drill string damping factor and equivalent load factor.

[0115] In the optimization step S130, the correction parameters are determined based on the contact deformation of the well wall to correct the equivalent load vector. The dynamic model of the equivalent evaluation drill string assembly is solved to calculate the displacement vector of the drill string unit before and after the load vector is corrected. The displacement, velocity and acceleration vectors of the target node are determined based on the contact deformation deviation of the same constraint node.

[0116] The evaluation model construction step S140 involves using the dynamic model of the drill string in the equivalent evaluation drill string assembly to solve for the dynamic lateral force and dynamic rotation angle of the drill bit. A drilling trend angle calculation model for the equivalent evaluation drill string assembly is established by comprehensively considering the drill bit cutting index, thereby evaluating the dynamic drilling trend of the target bent screw drill string assembly. For technical operations that are the same or similar to those in the above embodiments, this embodiment will not repeat them; only the following distinguishing technical features will be further explained.

[0117] To obtain practical and comprehensive evaluation results, ensuring the integrity of the input data is crucial. Therefore, before performing the evaluation using the constructed drilling trend angle calculation model, the researchers of this invention pre-established a list storing comprehensive model input data. Specifically, the list also stores direct model input data (for equivalent evaluation drill string assemblies) and actual drill string assembly status data meeting evaluation requirements (for the target curved screw drill string assembly).

[0118] Therefore, in a preferred embodiment, the method further includes:

[0119] The evaluation data creation steps include: pre-creating an evaluation data list, which stores data on different drill bit combinations, drilling pressure, and rotation speed for bent screw drill bit combinations, and also stores corresponding drill bit lateral force, drill bit dynamic rotation angle, and drill bit cutting data for equivalent evaluation drill bit combinations.

[0120] During the evaluation, the parameters of the drilling trend angle calculation model are set according to the drill bit lateral force, drill bit dynamic rotation angle and drill bit cutting data. The drilling state parameters to be tested are input, and the evaluation results are obtained by analyzing the trend angle data output by the model.

[0121] In practical applications, both professional and novice workers can effectively obtain evaluation results if they clearly understand the evaluation requirements. Specifically, based on the evaluation requirements, one or more drill bit combinations, drilling pressure, and rotation speed data that match the requirements can be selected from the evaluation data list. The parameters of the drilling trend angle calculation model can be set by selecting the associated drill bit lateral force, drill bit dynamic rotation angle, and drill bit cutting data. This allows for the rapid and efficient acquisition of drilling trend data for the drill bit combination corresponding to the evaluation requirements.

[0122] Example 3

[0123] The methods described in detail in the above-disclosed embodiments of the present invention can be implemented using various forms of devices or systems. Therefore, based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a system for evaluating the dynamic drilling trend of a bent screw drill assembly. This system is used to execute the method for evaluating the dynamic drilling trend of a bent screw drill assembly as described in any one or more of the above embodiments. Specific embodiments are given below for detailed description.

[0124] Specifically, Figure 7 The diagram shows a structural schematic of a system for evaluating the dynamic drilling trend of a bent screw drill assembly provided in an embodiment of the present invention, as shown below. Figure 7 As shown, the system includes:

[0125] The equivalent setting module 71 is configured to analyze the structural characteristics and operating principle of the target bent screw drill assembly, design the corresponding equivalent principle, and determine the straight beam drill assembly that can accurately replace the target bent screw drill assembly to achieve the expected drilling effect based on the equivalent principle, as the equivalent evaluation drill assembly;

[0126] The dynamic model establishment module 73 is configured to discretize the equivalent evaluation drill string assembly, derive the dynamic control equation of the drill string unit based on the variational principle of dynamic problems, and then integrate the drill string stiffness factor, drill string mass factor, drill string damping factor and equivalent load factor to obtain the dynamic model of the overall drill string assembly.

[0127] The computation optimization module 75 is configured to solve the dynamic model of the equivalent evaluation drill string assembly, calculate the displacement vector of the drill string unit, and correct the equivalent load vector based on it until the displacement vector of the same drill string unit node satisfies the set conditions.

[0128] The evaluation model construction module 77 is configured to use the dynamic model of the drill string in the equivalent evaluation drill string assembly to solve for the dynamic lateral force and dynamic rotation angle of the drill bit, and to establish a drilling trend angle calculation model of the equivalent evaluation drill string assembly by comprehensively considering the drill bit cutting index, so as to evaluate the dynamic drilling trend of the target bent screw drill string assembly.

[0129] Furthermore, in one embodiment, the equivalent setting module is specifically configured to perform the following operations:

[0130] The equivalent position of applying concentrated load in the equivalent evaluation drill string assembly is analyzed so that the equivalent evaluation drill string assembly after the concentrated load is applied can accurately reflect the stress state of the bending angle of the target bent screw drill string assembly.

[0131] Mechanical models of the target bent screw drill assembly and mechanical models of the drill assembly after applying load at the target equivalent position are established respectively. Based on the established models, the bending moment at the bend and the bending moment at the equivalent position are calculated respectively. Then, the equivalent concentrated load value to be applied is determined based on the calculation results.

[0132] Based on the principle that the sum of the centrifugal forces generated by the drill bits on both sides of the bend is equal to the centrifugal force generated by the equivalent mass eccentricity of the equivalent evaluation drill bit assembly, the equivalent mass eccentricity of the equivalent evaluation drill bit assembly is derived.

[0133] Specifically, in one embodiment, the equivalent setting module analyzes the equivalent location of the concentrated load applied in the equivalent evaluation drill string assembly through the following operations:

[0134] Based on the location of the bend in the bent screw drill assembly, the same location is selected in the equivalent straight beam drill assembly as the target equivalent location for applying the lateral concentrated load; usually, the location of the applied load remains unchanged during the analysis and evaluation process.

[0135] In one embodiment, the equivalent setting module uses the longitudinal and transverse bending beam method to establish a mechanical model of the target bent screw drill assembly and determine the bending moment at the bend. After applying a first concentrated load at the target equivalent position, the longitudinal and transverse bending beam method is used to establish a mechanical model of the equivalent evaluation drill assembly and calculate the bending moment at the equivalent position. If they are not equal, the applied load value is adjusted to a second concentrated load, the mechanical model is re-established and the bending moment at the equivalent position is calculated, until the two bending moments are equal. The currently applied load value is taken as the target equivalent load value.

[0136] Furthermore, in one embodiment, the dynamic model building module is configured to: discretize the drill string assembly using spatial beam elements, derive the dynamic control equations of the drill string elements based on the variational principle of dynamic problems, and further aggregate to obtain the overall drill string stiffness matrix, mass matrix, damping matrix, and equivalent load vector.

[0137] In one embodiment, the computation optimization module is specifically configured to perform the following steps:

[0138] Step A1: Calculate the displacement vector of the drill string element using the Newmark numerical solution method, and determine the contact state between the drill string and the wellbore based on the calculated drill string element position vector and the wellbore clearance.

[0139] Step A2: Combine the results of the integrated contact state judgment with the equivalent load vector corrected for the wellbore contact deformation;

[0140] Step A3: After correcting the equivalent load vector, calculate the displacement vector of the drill string element using the Newmark numerical solution method, and proceed to step A4;

[0141] Step A4: Determine whether the node numbers of the constraint points are consistent. If they are consistent, further analyze whether the contact deformation deviation is within the allowable error range. If the contact deformation deviation is within the allowable error range, save the current node displacement, velocity, and acceleration vectors and go to step A1. Otherwise, go to step A5.

[0142] Step A5: Return to step A1 and repeat until both conditions are met simultaneously.

[0143] Furthermore, in the computation optimization step, for a new time step, steps A1 to A5 are repeated and the computation is terminated when the time step meets the predetermined time length.

[0144] Specifically, the force generated by the contact between the drill string unit node and the wellbore is calculated using the following formula:

[0145]

[0146] In the formula, F n For contact force, k c The contact stiffness between the drill string and the wellbore is given by Δ = u. r -δ represents the wellbore deformation. Where Δ<0 indicates that the drill string node is not in contact with the wellbore, and Δ≥0 indicates that the drill string node is in contact with the wellbore. The value of the equivalent load vector is then corrected based on the force calculation result, for example, by vectorizing the force and summing it with the current equivalent load vector.

[0147] In another alternative embodiment, during practical application, in order to correct the applied concentrated load based on the accurate dynamic model stress condition, the radial constraint force, tangential resistance, axial resistance, and frictional torque of the drill string can be calculated as correction parameters based on the wellbore contact deformation to correct the equivalent load vector.

[0148] Furthermore, the dynamic lateral force and dynamic rotation angle of the drill bit are obtained by using the drill string dynamic analysis model. Considering the influence of drill bit anisotropy, a drilling trend angle calculation model for drill string assemblies that comprehensively considers the influence of drill bit lateral force, drill bit rotation angle, and drill bit cutting anisotropy index is established to achieve the drilling trend evaluation target of bent screw drill string assemblies under different drill string assemblies and drilling parameter conditions.

[0149] Specifically, in one embodiment, the target drill bit drilling trend angle is calculated according to the following mathematical model:

[0150]

[0151] In the formula, A P For drilling trend angle; F y F represents the dynamic lateral force of the drill bit. x For drilling pressure; I bHere, represents various drill bit indices; α represents the dynamic drill bit rotation angle. Substituting the results from the drill string dynamics model into the above formula yields the dynamic well inclination trend angle of the drill string assembly.

[0152] Furthermore, in a preferred embodiment, the system further includes: an evaluation data creation module, configured as follows:

[0153] An evaluation data list is pre-created, which stores data on different drill bit combinations, drilling pressure and rotation speed for bent screw drill bit combinations. It also stores corresponding drill bit lateral force, drill bit dynamic rotation angle and drill bit cutting data for equivalent evaluation drill bit combinations.

[0154] During the evaluation, the parameters of the drilling trend angle calculation model are set according to the drill bit lateral force, drill bit dynamic rotation angle and drill bit cutting data. The drilling state parameters to be tested are input, and the evaluation results are obtained by analyzing the trend angle data output by the model.

[0155] In the system for evaluating the dynamic drilling trend of the bent screw drill assembly provided by the embodiments of the present invention, each module or unit structure can operate independently or in combination according to actual calculation and evaluation requirements to achieve the corresponding technical effects.

[0156] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0157] The phrase "an embodiment" in the specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0158] 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 evaluating the dynamic drilling trend of a bent screw drill assembly, characterized in that, The method includes: The equivalent setting steps involve analyzing the structural characteristics and operating principle of the target bent screw drill assembly to design the corresponding equivalent principles. Based on these equivalent principles, a straight beam drill assembly that can accurately replace the target bent screw drill assembly to achieve the expected drilling effect is determined as the equivalent evaluation drill assembly. After discretizing the equivalent evaluation drill string assembly, the dynamic model is established by deriving the dynamic control equation of the drill string unit based on the variational principle of dynamic problems. Then, the dynamic model of the overall drill string assembly is obtained by integrating the drill string stiffness factor, drill string mass factor, drill string damping factor and equivalent load factor. The calculation optimization steps involve solving the equivalent evaluation of the dynamic model of the drill string assembly, calculating the displacement vector of the drill string unit, and correcting the equivalent load vector based on it until the displacement vector of the same drill string unit node satisfies the set conditions. The evaluation model construction steps are as follows: the dynamic lateral force and dynamic rotation angle of the drill bit are obtained by using the dynamic model of the drill string in the equivalent evaluation drill string assembly. The drilling trend angle calculation model of the equivalent evaluation drill string assembly is established by combining the drill bit cutting index, so as to evaluate the dynamic drilling trend of the target bent screw drill string assembly. The equivalent setup step includes the following operations: The equivalent position of applying concentrated load in the equivalent evaluation drill string assembly is analyzed so that the equivalent evaluation drill string assembly after the concentrated load is applied can accurately reflect the stress state of the bending angle of the target bent screw drill string assembly. Mechanical models of the target bent screw drill assembly and mechanical models of the drill assembly after applying load at the target equivalent position are established respectively. Based on the established models, the bending moment at the bend and the bending moment at the equivalent position are calculated respectively. Then, the equivalent concentrated load value to be applied is determined based on the calculation results. Based on the principle that the sum of the centrifugal forces formed by the drill bits on both sides of the bend is equal to the centrifugal force formed by the equivalent mass eccentricity of the equivalent evaluation drill bit assembly, the equivalent mass eccentricity of the equivalent evaluation drill bit assembly is derived. In the evaluation model construction step, the drilling trend angle calculation model for the equivalent evaluation drill string assembly is established by combining the drill bit cutting index as follows: In the formula, For drilling trend angle; This refers to the dynamic lateral force of the drill bit; For drilling pressure; This is a data set of various indexes for the drill bit; The dynamic rotation angle of the drill bit is given; the solution of the drill string dynamics model is substituted into the above formula to obtain the required drilling trend angle of the drill string assembly.

2. The method as described in claim 1, characterized in that, In the equivalent setup step, based on the position of the bend in the bent screw drill bit assembly, the same position is selected in the equivalent replacement straight beam drill bit assembly as the target equivalent position for applying the lateral concentrated load.

3. The method as described in claim 1, characterized in that, The equivalent setup steps include: The mechanical model of the target bent screw drill assembly is established using the longitudinal and transverse bending beam method, and the bending moment at the bend is determined. After applying the first concentrated load at the target equivalent position, the mechanical model of the equivalent evaluation drill assembly is established using the longitudinal and transverse bending beam method, and the bending moment at the equivalent position is calculated. If they are not equal, the applied load value is adjusted to the second concentrated load, the mechanical model is re-established, and the bending moment at the equivalent position is calculated until the two bending moments are equal. The currently applied load value is taken as the target equivalent load value.

4. The method as described in claim 1, characterized in that, In the dynamic model establishment step, the drill string assembly is discretized using spatial beam elements. Based on the variational principle of dynamic problems, the dynamic control equations of the drill string elements are derived, and then the overall drill string stiffness matrix, mass matrix, damping matrix, and equivalent load vector are obtained.

5. The method as described in claim 1, characterized in that, The computation optimization step includes: Step A1: Calculate the displacement vector of the drill string element using the Newmark numerical solution method, and determine the contact state between the drill string and the wellbore based on the calculated drill string element position vector and the wellbore clearance. Step A2: Combine the results of the integrated contact state judgment with the equivalent load vector corrected for the wellbore contact deformation; Step A3: After correcting the equivalent load vector, calculate the displacement vector of the drill string element using the Newmark numerical solution method, and proceed to step A4; Step A4: Determine whether the node numbers of the constraint points are consistent. If they are consistent, further analyze whether the contact deformation deviation is within the allowable error range. If the contact deformation deviation is within the allowable error range, save the current node displacement, velocity, and acceleration vectors and go to step A1. Otherwise, go to step A5. Step A5: Return to step A1 and repeat until both conditions are met simultaneously.

6. The method as described in claim 5, characterized in that, In the computation optimization step, for a new time step, steps A1 to A5 are repeated and the computation is terminated when the time step meets the predetermined time length.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes: An evaluation data list is pre-created, which stores data on different drill bit combinations, drilling pressure and rotation speed for bent screw drill bit combinations. It also stores corresponding drill bit lateral force, drill bit dynamic rotation angle and drill bit cutting data for equivalent evaluation drill bit combinations. During the evaluation, the parameters of the drilling trend angle calculation model are set according to the drill bit lateral force, drill bit dynamic rotation angle and drill bit cutting data. The drilling state parameters to be tested are input, and the evaluation results are obtained by analyzing the trend angle data output by the model.

8. A storage medium, characterized in that, The storage medium stores program code capable of implementing the method as described in any one of claims 1 to 7.

9. A system for evaluating the dynamic drilling trend of a bent screw drill assembly, characterized in that, The system performs the method as described in any one of claims 1 to 7.

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