Fatigue risk prediction method based on extremum analysis and terminal

Abstract

The invention particularly relates to a fatigue risk prediction method and terminal based on extreme value analysis, and the method comprises the steps: obtaining the performance parameters of a drilling tool, the performance parameters comprising any two or more of torque, alternating stress, tension, pressure, working time and drilling depth; and when any one of the performance parameters is greater than an extreme threshold value, triggering early warning of the drilling tool, and executing emergency operation based on different performance parameters. According to the method, extreme value early warning is conducted on any performance parameter of the drilling tool, global control over any possible fatigue risk is achieved, meanwhile, different emergency operations are executed based on the extreme value threshold value, and the use value of the drilling tool is exerted under the condition that the safety of the drilling tool is guaranteed to the maximum extent.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling tools, and in particular to a fatigue risk prediction method and a terminal based on extreme value analysis. Background Art

[0002] In the process of exploiting resources such as oil and natural gas, drilling operations are a crucial link. As the key equipment for drilling, drill bits are subjected to a variety of complex loads in a complex and harsh underground environment, which makes them prone to fatigue damage. According to statistics, more than 80% of drill bit failures are due to fatigue damage. Fatigue damage of drill bits is a very serious problem. It may lead to underground accidents such as drill bit breakage and drill bit sticking, which will affect the drilling progress, increase costs, and may pose a threat to personnel safety.

[0003] For example, CN113065211A discloses a bottom drill assembly fatigue life prediction method based on drill string dynamics, which predicts drill fatigue in a dynamic way to improve the effectiveness of drill life prediction.

[0004] For example, CN103967428B discloses a method for evaluating the risk of fatigue failure of a drill string, and also discloses a method for predicting fatigue of a drill tool, which determines the fatigue condition of the drill tool by means of the wellbore structure, the drill tool assembly structure, and the wellbore trajectory parameters.

[0005] The prior art all provides a single-dimensional fatigue prediction method. In fact, there are many key factors that affect drill tool fatigue, such as torque, alternating stress, tension, etc., which will affect the fatigue of the drill tool, thereby causing the accuracy of the drill tool life prediction results obtained by the above technical solution to deviate. In addition, the prior art CN113065211A mainly uses a dynamic method, which requires comprehensive consideration of multiple mechanical factors such as system kinetic energy, system potential energy, system gravity, and system centrifugal force, and the prediction method is relatively complex; while CN103967428B needs to consider the wellbore structure, drill tool assembly structure, and actual wellbore trajectory parameters. There are too many external factors involved. Although the accuracy can be improved, the system complexity is greatly increased, and the universality is not strong. Summary of the invention

[0006] In view of the technical problems in the prior art that single considerations easily lead to deviations in prediction results and that excessive involvement of external factors leads to complexity, the present invention provides a fatigue risk prediction method based on extreme value analysis, which has at least the advantages of high comprehensiveness, single monitoring factor, strong universality, and accurate prediction results.

[0007] First aspect

[0008] The present invention provides a fatigue risk prediction method based on extreme value analysis, comprising:

[0009] Obtaining performance parameters of the drilling tool, wherein the performance parameters include any combination of two or more of alternating stress, tension, drilling depth, torque, pressure and working time;

[0010] When any of the performance parameters is greater than its extreme value threshold, a drilling tool warning is triggered, and emergency operations are performed based on the difference in the performance parameters.

[0011] Specifically, the main technical concept of the present invention is to provide extreme value warning for any performance parameter of the drilling tool, to achieve global control of any possible fatigue risk, and at the same time perform different emergency operations based on extreme value thresholds, so as to maximize the use value of the drilling tool while ensuring the safety of the drilling tool to the greatest extent.

[0012] Furthermore, the emergency operation includes: switching drilling tools, controlling torque growth, and controlling displacement;

[0013] The operation of switching the drilling tool is used in the following scenarios: the alternating stress, tension or drilling depth is greater than its extreme value threshold;

[0014] The operation of controlling the torque growth is used in the following scenarios: the torque is greater than its extreme value threshold;

[0015] The control displacement is used in the following scenario: the pressure or the working time is greater than its extreme value threshold.

[0016] Further, if the operation of controlling torque growth or controlling displacement is performed, or the drilling tool warning is not triggered, the composite damage value D is calculated according to the following formula:

[0017]

[0018] k represents the number of performance parameters, D i represents the value of the i-th performance parameter, i∈[1,k], and i is an integer;

[0019] When D is greater than the composite damage threshold, the drilling tool warning is triggered.

[0020] Specifically, one of the main technical concepts of the present invention is to control the potential risks of drilling tools through composite damage values. Although the use risk of drilling tools can be alleviated to a certain extent after triggering the control torque growth and displacement control operations, the risk is still higher than when the emergency operation is not triggered, and all the performance parameters of the drilling tools have not triggered extreme value warnings, and there are still potential risks. Therefore, by controlling the composite damage value, the safety and reliability of drilling tool operations can be effectively improved.

[0021] Further, setting a first priority and a second priority for the detection of the performance parameter;

[0022] The alternating stress, tension and drilling depth are placed at the first priority;

[0023] The torque, pressure and operating time are given second priority.

[0024] It is worth explaining that the priority level of the first priority level is greater than the priority level of the second priority level.

[0025] Furthermore, the calculation formula of the torque is as follows:

[0026]

[0027] f(x) represents the probability density at a given x, σ represents the standard deviation, and μ represents the mean.

[0028] Optionally, the tension F ab The calculation formula is as follows:

[0029] F ab =∑[L d W air cosθ+F drag +ΔF area ]-F btm -W bit +F bsf ;

[0030] L d Indicates the length of downhole drilling tools, W air represents the linear density of the drilling tool, θ represents the well inclination of the drilling tool, F drag Indicates the friction resistance of the drill bit, ΔF area It indicates the pressure difference of drilling fluid caused by the difference in size between the drill bit joint and the drill bit as a whole. btm Indicates the pressure generated by the bottom hole fluid, W bit Indicates drilling pressure, F bsf represents the buckling stability force.

[0031] Optionally, the pressure is calculated as follows:

[0032] p e =p a +∑(g a D tvd ),

[0033] p i =p s +∑(g s D tvd );

[0034] p e Indicates the external pressure of the drilling tool, p a Indicates the drilling tool annulus pressure, ga represents the annular pressure gradient, D tvd Indicates the vertical depth of the well section where the drilling tool is located, p i Indicates the pressure inside the drill bit, p s Indicates the internal pressure of the drilling tool, g s Indicates the string pressure gradient.

[0035] Optionally, the process of obtaining the alternating stress is as follows:

[0036] The main frequency components and the corresponding maximum and minimum amplitudes are identified based on the frequency domain analysis method.

[0037] Optionally, the process of obtaining the working hours is as follows:

[0038] Based on the total duration of the drilling operation, the total duration includes n time intervals according to the working intensity and load changes, and the time periods that significantly affect the fatigue life in all time intervals are obtained.

[0039] Optionally, the process of obtaining the drilling depth is as follows:

[0040] According to the drilling depth record of the drill bit, the maximum and minimum values ​​of the drilling depth are obtained, and the extreme value of the drilling depth is calculated in combination with the hardness difference of the formation.

[0041] Second aspect

[0042] The present invention provides a terminal, comprising a fatigue risk prediction method based on extreme value analysis as provided in any possible embodiment of the first aspect.

[0043] In summary, the present invention provides a fatigue risk prediction method and terminal based on extreme value analysis, which have at least the following advantages:

[0044] 1. The present invention provides an extreme value warning for any performance parameter of the drilling tool, realizes global control of any possible fatigue risk, and performs different emergency operations based on the extreme value threshold, so as to maximize the use value of the drilling tool while ensuring the safety of the drilling tool to the greatest extent;

[0045] 2. The present invention controls the potential risks of drilling tools through composite damage values. Even if all performance parameters of the drilling tools do not trigger extreme value warnings, the potential risks of drilling tools can be controlled through composite damage values, thereby improving the safety and reliability of drilling tool operations.

[0046] 3. The present invention only uses the performance parameters of the drill tool as the main consideration factor for the fatigue life of the drill tool. The reliability of the evaluation factors is strong and the parameters are easy to obtain, which reduces the complexity of predicting the fatigue risk of the drill tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments, but those skilled in the art will appreciate that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be used as a limitation on the scope of the present invention. In addition, unless otherwise specified, the drawings are only schematically representing the composition or structure of the described objects and may contain exaggerated displays, and the drawings are not necessarily drawn to scale.

[0048] Figure 1 A schematic flow chart of a fatigue risk prediction method based on extreme value analysis provided by an embodiment of the present invention;

[0049] Figure 2 A working schematic diagram of a fatigue risk prediction method based on extreme value analysis provided by one embodiment of the present invention;

[0050] Figure 3 A schematic diagram of the structure of a terminal provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The following is combined with Figures 1 to 3 , the present invention is described in detail.

[0052] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] The main technical concept of the present invention is to use multiple performance parameters of the drill tool as the analysis basis and comprehensively consider the service life of the drill tool to improve the reliability and accuracy of the prediction of the drill tool life.

[0054] For further information, see Figure 1 The figure is a flow chart of a fatigue risk prediction method based on extreme value analysis provided by one embodiment of the present invention.

[0055] Example 1

[0056] First, the performance parameters of the drilling tool are obtained through step S10, and then in step S20, when any of the performance parameters is greater than its extreme value threshold, the drilling tool warning is triggered, and emergency operations are performed based on the difference in the performance parameters. The performance parameters include any combination of two or more of torque, alternating stress, tension, pressure, working time and drilling depth.

[0057] It is worth explaining that there are 57 or more combinations of performance parameters, including 15 in groups of two, 20 in groups of three, 15 in groups of four, 6 in groups of five and 1 in groups of six, and as the number of performance parameters increases, the ability to resist the risk of drill bit breakage becomes stronger.

[0058] Optionally, the performance parameters also include other variables that can be used as a predictor of drilling tool fatigue risk.

[0059] For further information, see Figure 2 Shown is a working schematic diagram of a fatigue risk prediction method based on extreme value analysis provided by an embodiment of the present invention.

[0060] Example 2

[0061] Taking the full performance parameters in Example 1 as an example, the workflow of this application is analyzed: according to the torque analysis, it is determined whether the torque is greater than its extreme threshold. If so, a drill tool warning is triggered and an emergency operation is performed; otherwise, the analysis of other performance parameters continues. The analysis of other performance parameters is consistent with the torque analysis. When it is greater than its extreme threshold, if so, a drill tool warning is triggered and an emergency operation is performed.

[0062] Optionally, when the torque is greater than its extreme threshold, the operation of switching the drilling tool is performed; when the alternating stress is greater than its extreme threshold, the operation of controlling the torque growth is performed; when the tension is greater than its extreme threshold, the operation of switching the drilling tool or controlling the friction is performed; when the pressure is greater than its extreme threshold, the operation of controlling the displacement or reducing the density is performed; when the working time is greater than its extreme threshold, the operation of controlling the displacement is performed; when the drilling depth is greater than its extreme threshold, the operation of switching the drilling tool is performed.

[0063] Optionally, although multiple combinations of performance parameter detection are provided in Example 1, in fact, the performance parameters have a preferred combination. The present invention sets the first priority and the second priority for the detection of the performance parameters; the alternating stress, tension and drilling depth are placed at the first priority; the torque, pressure and working time are placed at the second priority.

[0064] In one possible implementation, the performance parameters include all parameters of the first priority; in another possible implementation, the performance parameters include all parameters of the first priority and at least some parameters of the second priority. By configuring the first priority and the second priority, the detection complexity can be appropriately simplified while ensuring a high risk of resistance to drill tool breakage.

[0065] Example 3

[0066] On the basis of Example 2, if the operation of controlling torque growth or displacement is performed, or if the drilling tool warning is not triggered, the composite damage value is calculated according to the formula k represents the number of performance parameters, D i represents the value of the i-th performance parameter, i∈[1,k], and i is an integer; when D is greater than the composite damage threshold, the drilling tool warning is triggered. Figure 2 The remaining life analysis is performed in the process. If the drilling tool warning is not triggered, the current drilling tool continues to be used. If it is triggered, the current drilling tool is stopped.

[0067] It is worth explaining that composite damage analysis is a permanent analysis process. Regardless of whether the performance parameters trigger the drill tool warning, as long as the composite damage analysis triggers the drill tool warning, it can be determined that the current drill tool is at the life limit and there is a risk of fracture.

[0068] Optionally, after executing the drilling tool switching operation, re-enter the extreme value analysis.

[0069] Optionally, after executing the operation of controlling the torque growth or controlling the displacement, if the composite damage analysis is passed, the extreme value analysis is performed again.

[0070] Furthermore, in the process of performing the extreme value analysis, the performance parameter that triggers the control of the torque increase or the control of the displacement is placed at the first priority.

[0071] Example 4

[0072] Based on the embodiment 2 or 3, a pre-evaluation process is provided, and only the drilling tools that pass the pre-evaluation are put into use, and the drilling tools that fail the pre-evaluation are used for recycling. At the same time, the recycled drilling tools are evaluated for recycling, and when they pass the recycling evaluation, the drilling tools are stopped from use. If they fail the recycling evaluation, extreme value analysis is performed. This ensures that the drilling tools in use are in a reliable state and reduces the problem of unreasonable waste of drilling tools caused by misjudgment.

[0073] For further information, see Figure 3 FIG. 1 is a schematic diagram of the structure of a terminal provided by an embodiment of the present invention.

[0074] Example 5

[0075] The present invention provides a terminal, comprising an acquisition unit and a confirmation unit, wherein the acquisition unit is used to acquire performance parameters of a drilling tool, and the confirmation unit is used to trigger a drilling tool warning when any of the performance parameters is greater than its extreme value threshold, and to perform emergency operations based on the difference in the performance parameters.

[0076] It is worth explaining that the working principle of the terminal can be understood by referring to any one of Embodiments 1-4.

[0077] The present invention is described in detail above. The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the present invention and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A fatigue risk prediction method based on extreme value analysis, characterized in that: include: Obtaining performance parameters of the drilling tool, wherein the performance parameters include any combination of two or more of alternating stress, tension, drilling depth, torque, pressure and working time; When any of the performance parameters is greater than its extreme value threshold, a drilling tool warning is triggered, and emergency operations are performed based on the difference in the performance parameters.

2. A fatigue risk prediction method based on extreme value analysis as claimed in claim 1, characterized in that: The emergency operations include: switching drilling tools, controlling torque growth, and controlling displacement; The operation of switching the drilling tool is used in the following scenarios: the alternating stress, tension or drilling depth is greater than its extreme value threshold; The operation of controlling the torque growth is used in the following scenarios: the torque is greater than its extreme value threshold; The control displacement is used in the following scenario: the pressure or the working time is greater than its extreme value threshold.

3. A fatigue risk prediction method based on extreme value analysis as claimed in claim 2, characterized in that: If the above-mentioned operation of controlling torque growth or controlling displacement is performed, or the drilling tool warning is not triggered, the composite damage value D is calculated according to the following formula: k represents the number of performance parameters, D i represents the value of the i-th performance parameter, i∈[1,k], and i is an integer; When D is greater than the composite damage threshold, the drilling tool warning is triggered.

4. A fatigue risk prediction method based on extreme value analysis as claimed in claim 2 or 3, characterized in that: Setting a first priority and a second priority for detection of the performance parameter; The alternating stress, tension and drilling depth are placed at the first priority; The torque, pressure and operating time are given second priority.

5. A fatigue risk prediction method based on extreme value analysis as claimed in claim 4, characterized in that: The torque calculation formula is as follows: f(x) represents the probability density at a given x, σ represents the standard deviation, and μ represents the mean.

6. A fatigue risk prediction method based on extreme value analysis as claimed in claim 4, characterized in that: The pulling force F ab The calculation formula is as follows: F ab =∑[L d W air cosθ+F drag +ΔF area ]-F btm -W bit +F bsf ; L d Indicates the length of downhole drilling tools, W air represents the linear density of the drilling tool, θ represents the well inclination of the drilling tool, F drag Indicates the friction resistance of the drill bit, ΔF area It indicates the pressure difference of drilling fluid caused by the difference in size between the drill bit joint and the drill bit as a whole. btm Indicates the pressure generated by the bottom hole fluid, W bit Indicates drilling pressure, F bsf represents the buckling stability force.

7. A fatigue risk prediction method based on extreme value analysis as claimed in claim 4, characterized in that: The pressure is calculated as follows: p e =p a +Σ(g a D tvd ), p i =p s +Σ(g s D tvd ); p e Indicates the external pressure of the drilling tool, p a Indicates the drilling tool annulus pressure, g a represents the annular pressure gradient, D tvd Indicates the vertical depth of the well section where the drilling tool is located, p i Indicates the pressure inside the drill bit, p s Indicates the internal pressure of the drilling tool, g s Indicates the string pressure gradient.

8. A fatigue risk prediction method based on extreme value analysis as claimed in claim 4, characterized in that: The process of obtaining the alternating stress is as follows: The main frequency components and the corresponding maximum and minimum amplitudes are identified based on the frequency domain analysis method.

9. A fatigue risk prediction method based on extreme value analysis as claimed in claim 4, characterized in that: The process of obtaining the working hours is as follows: Based on the total duration of the drilling operation, the total duration includes n time intervals according to the working intensity and load changes, and the time periods that significantly affect the fatigue life in all time intervals are obtained.

10. A terminal, characterized in that: It includes a fatigue risk prediction method based on extreme value analysis as described in any one of claims 1 to 9.

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