Experimental method and device for preventing bending instability of casing pipe, storage medium and processor

Abstract

The invention discloses an experimental method and device for preventing bending instability of a casing pipe, a storage medium and a processor. The method comprises the following steps: 1, fixing the casing pipe, and respectively applying axial compression force and upward longitudinal bending force; 2, the axial compression force and the longitudinal bending force are sequentially increased; 3, detecting stress-strain data of the stressed part of the sleeve in real time, and when the detected stress-strain data starts to decrease, indicating that the root of the thread of the sleeve begins to crack and the two ends of the sleeve coupling start to bend so as to obtain critical data of bending instability of the sleeve in the state; and 4, changing the initial value of the axial compression force and the initial value of the longitudinal bending force, changing the process value of increasing the axial compression force and the process value of increasing the longitudinal bending force each time, and repeating the steps for many times to obtain critical data of bending instability of the casing in each state. According to the technology, the critical data of the bending instability of the casing pipe can be found out through experiments, and the purposes of subsequently preventing the bending instability of the casing pipe, avoiding safety accidents and improving the construction safety are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of casings of oil and gas wells, and in particular to an experimental method, a device, a storage medium and a processor for preventing casing bending and instability. Background Art

[0002] The casing's anti-external collapse strength is one of the important performance indicators of the casing. With the increasing number of deep wells, ultra-deep wells, high-pressure gas wells, high-temperature and high-pressure wells, and other oil and gas wells, the drilling cost is decreasing year by year, and the requirements for the casing's anti-collapse performance are getting higher and higher, and the failure accidents of oil and gas wells are also increasing. The reason for its failure is that the anti-collapse strength is checked according to the collapse pressure formula derived from the ideal circular section in the design, which is difficult to accurately reflect the actual safety anti-collapse performance of the pipe, thus affecting the actual use effect of the oil field.

[0003] The current technical solution of the casing anti-external extrusion test device is: it includes a horizontally lying cylindrical barrel, a sealing assembly, a support frame and a medium boosting unit; sealing assemblies are arranged inside the two ends of the barrel, a detection hole is arranged on the barrel wall, a catheter is connected to the barrel through the detection hole, and the other end of the catheter is connected to the medium boosting unit; a drain valve is arranged at the top of the barrel.

[0004] However, the above-mentioned casing anti-external extrusion test device can only measure the anti-external extrusion data when the casing is straight, and cannot measure the actual situation after the casing enters the well. The reason is that the actual wellbore drilled is curved. After the casing is strung into the well, it will bend, and its anti-external extrusion ability will decrease with the degree of bending. When the casing thread is subjected to a sufficiently large bending force, it will cause cracks at the root of the casing thread and begin to break and suddenly lift up, which will cause damage to other equipment and safety accidents. For this reason, it is necessary to find out the data that is likely to cause casing bending instability in advance through experiments, so as to provide effective support for the subsequent safe lowering of the casing. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art, and to provide an experimental method, device, storage medium and processor for preventing casing bending and instability. The technology can find out the critical data of casing bending and instability through specific experiments, so as to control the casing through the critical data in subsequent construction, thereby achieving the purpose of preventing casing bending and instability, avoiding safety accidents and improving construction safety.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides an experimental method for preventing casing bending instability, characterized by comprising the following steps: Step 1: two casings connected by casing couplings are arranged transversely, and then an axial compression force is applied from one end of the casing to the other end and an upward longitudinal bending force is applied to the casing from the casing coupling; Step 2: Increase the axial compression force and the longitudinal bending force in sequence, and maintain the set time after each increase of the axial compression force and the longitudinal bending force; Step 3: Real-time detection of stress and strain data at the stress-bearing part of the casing. When it is detected that the stress and strain data begin to decrease, it indicates that cracks begin to form at the root of the casing thread and both ends of the casing coupling begin to bend. The axial compression force, longitudinal bending force and bending deflection of the casing in this state are recorded to obtain the critical data of casing bending instability in this state. Step 4: Change the initial value of the axial compression force and the initial value of the longitudinal bending force, and change the process value of each increase in the axial compression force and the process value of the longitudinal bending force. Repeat this process many times to obtain the axial compression force, longitudinal bending force and bending deflection of the casing under various states, and then obtain the critical data of casing bending instability under various states.

[0007] The axial compressive force and the longitudinal bending force applied in step 1 may be the same or different.

[0008] The axial compressive force in step 2 is increased by 5-10 tons each time.

[0009] The longitudinal bending force increased each time in step 2 is 1-5 tons.

[0010] The setting time in step 2 is 3-5 minutes.

[0011] In step 3, stress strain gauges are used to detect stress and strain data at the casing end and casing coupling respectively.

[0012] In a second aspect, the present invention provides an experimental device for preventing casing bending instability, characterized by comprising: A base, used for horizontally placing a casing string to be tested formed by connecting two casings through a casing coupling; A longitudinal hydraulic cylinder, fixed in the middle of the base, is used to apply an upward longitudinal bending force to the casing coupling of the casing string; An axial hydraulic cylinder, disposed at the end of the casing string, for applying an axial compression force to the other end of the casing string; A hydraulic pump, used to control the longitudinal hydraulic cylinder and the axial hydraulic cylinder respectively through hydraulic pipelines; Stress strain gauges are fixed between the longitudinal hydraulic cylinder and the casing string and between the axial hydraulic cylinder and the casing string, respectively, and are used to detect stress and strain data at the stress-bearing part of the casing string; A multifunctional display, connected to the hydraulic pump and the stress strain gauge, respectively, for recording and displaying axial compression force, longitudinal bending force and stress strain data; The base includes a transverse seat and a vertical seat, the vertical seats are symmetrically fixed at both ends of the transverse seat, one end of the casing string can move through one of the vertical seats and then abut against the other vertical seat; the longitudinal hydraulic cylinder is fixed under the casing coupling through the transverse seat, and the axial hydraulic cylinder is fixed to the other end of the casing string through the transverse seat.

[0013] In a third aspect, the present invention provides a storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the above-mentioned experimental method for preventing casing bending instability.

[0014] In a fourth aspect, the present invention provides a processor, wherein the processor is used to run a program, wherein the program executes the above-mentioned experimental method for preventing casing bending instability when running.

[0015] The advantages of adopting the present invention are: 1. The present invention adopts a specific experimental method and experimental device to perform compression and bending experiments on the end and middle of the casing string, which can find out the critical data of casing bending instability under different states. In this way, the casing can be controlled by these critical data in subsequent construction, thereby achieving the purpose of preventing casing bending instability, avoiding safety accidents and improving construction safety.

[0016] 2. In the present invention, the axial compression force and longitudinal bending force initially applied during the experiment may be the same or different, and the force added each time may be the same or different. By coordinating the two, critical data under different states (different axial compression forces and different longitudinal bending forces) can be obtained, which is beneficial to provide more accurate and effective guidance for complex construction conditions and has higher practicality.

[0017] 3. The present invention uses stress strain gauges to detect stress and strain data at the casing end and casing coupling, which has the advantages of high accuracy and good timeliness.

[0018] 4. The present invention uses a base, a longitudinal hydraulic cylinder, an axial hydraulic cylinder, a hydraulic pump, a stress strain gauge and a multi-functional display as an experimental device to experiment on the casing string, which has the advantages of a relatively simple structure, but is convenient for experiment and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of the present invention; Figure 2 It is a schematic diagram of the structure of the present invention.

[0020] Markings in the figure are: 1. lateral seat, 2. vertical seat, 3. casing column, 4. casing coupling, 5. stress strain gauge, 6. longitudinal hydraulic cylinder, 7. axial hydraulic cylinder, 8. hydraulic pump, 9. multi-function display, 10. hydraulic pipeline. DETAILED DESCRIPTION

[0021] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0022] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0023] It should also be understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0024] As used in the present specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]", depending on the context.

[0025] In addition, in the description of the present specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0026] References to "one embodiment" or "some embodiments" etc. described in the present specification mean that one or more embodiments of the present invention include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0027] Example 1 like Figure 1As shown, the present invention provides an experimental method for preventing casing bending instability, which comprises the following steps: Step 1: Set the two casings connected by the casing coupling horizontally. The horizontal setting mainly involves placing the casing horizontally, allowing one end to be compressed by external force, and the other end to abut against the substrate. Then apply axial compression force from one end of the casing to the other end and apply upward longitudinal bending force to the casing from the casing coupling, and maintain the setting time for 3-5 minutes after the force is applied.

[0028] It should be noted that this step is the first application of axial compression force and longitudinal bending force, and the applied axial compression force and longitudinal bending force may be the same or different.

[0029] Step 2: Increase the axial compression force and the longitudinal bending force in sequence. The axial compression force increased each time is 5-10 tons, and the longitudinal bending force increased each time is 1-5 tons. After each increase in the axial compression force and the longitudinal bending force, maintain the set time for 3-5 minutes.

[0030] Step 3: Real-time detection of stress and strain data at the stressed parts of the casing. Specifically, stress and strain gauges can be used to detect stress and strain data at the casing end and casing coupling. When it is detected that the stress and strain data begin to decrease, it indicates that cracks begin to form at the root of the casing thread and both ends of the casing coupling begin to bend. Record the axial compression force, longitudinal bending force and bending deflection of the casing under this state (under the axial compression force and longitudinal bending force) to obtain the critical data of casing bending instability under this state.

[0031] Step 4: Change the initial value of the axial compression force and the initial value of the longitudinal bending force, and change the process value of each increase in the axial compression force and the process value of the longitudinal bending force, repeat steps 1-3, repeat this multiple times to obtain the axial compression force, longitudinal bending force and bending deflection of the casing under various states, and then obtain the critical data of casing bending instability under various states.

[0032] The present invention can obtain critical data of bending instability at the casing threaded connection under various states (under various axial compression forces and various longitudinal bending forces) through the above method. In practical applications, it is only necessary to control the construction of the casing under the critical data to effectively prevent the casing from bending instability, thereby achieving the purpose of avoiding safety accidents and improving construction safety.

[0033] Example 2 like Figure 2 As shown, the present invention provides an experimental device for preventing casing bending instability, which is characterized by comprising: The base is used for horizontally placing a casing string 3 to be tested which is formed by connecting two casings through a casing collar 4.

[0034] Specifically, the base includes a transverse seat 1 with a certain length and a vertical seat 2 with a certain height. The vertical seat 2 is symmetrically fixed at the left and right ends of the transverse seat 1, and a through hole is opened on the right vertical seat 2. The left end of the casing column 3 moves through the through hole on the right vertical seat 2 and then abuts against the left vertical seat 2.

[0035] The longitudinal hydraulic cylinder 6 is fixed in the middle of the base and is used to apply an upward longitudinal bending force to the casing coupling 4 of the casing string 3 .

[0036] Specifically, the longitudinal hydraulic cylinder 6 is fixed below the casing coupling 4 via the transverse seat 1 , and can lift the casing coupling 4 to apply an upward longitudinal bending force to the casing string 3 .

[0037] The axial hydraulic cylinder 7 is arranged at the end of the casing string 3 and is used to apply axial compression force to the other end of the casing string 3 .

[0038] Specifically, the axial hydraulic cylinder 7 is fixed to the other end of the casing string 3 through the transverse seat 1 , and can apply axial compression force to the casing string 3 .

[0039] The hydraulic pump 8 is used to control the longitudinal hydraulic cylinder 6 and the axial hydraulic cylinder 7 respectively through the hydraulic pipeline 10.

[0040] The stress strain gauges 5 are respectively fixed between the longitudinal hydraulic cylinder 6 and the casing string 3 and between the axial hydraulic cylinder 7 and the casing string 3 , and are used to detect stress and strain data at the stress-bearing part of the casing string 3 .

[0041] The multifunctional display 9 is connected to the hydraulic pump 8 and the stress strain gauge 5 respectively, and is used to record and display the axial compression force, longitudinal bending force and stress strain data.

[0042] The experimental method of the experimental device of the present invention refers to Example 1, and will not be described in detail. The present invention can obtain critical data of bending instability at the casing threaded connection under various states (under various axial compression forces and various longitudinal bending forces) through the experimental device. In practical applications, it is only necessary to control the casing to be constructed under the critical data to effectively prevent the casing from bending instability, thereby achieving the purpose of avoiding safety accidents and improving construction safety.

[0043] Example 3 The present invention provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned experimental method for preventing casing bending instability is implemented.

[0044] In addition, the present invention also provides a processor, which is used to run a program, wherein the above-mentioned experimental method for preventing casing bending instability is executed when the program is running.

[0045] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. Experimental method to prevent casing bending instability, characterized by The following steps are involved: Step 1: two casings connected by casing couplings are arranged transversely, and then an axial compression force is applied from one end of the casing to the other end and an upward longitudinal bending force is applied to the casing from the casing coupling; Step 2: Increase the axial compression force and the longitudinal bending force in sequence, and maintain the set time after each increase of the axial compression force and the longitudinal bending force; Step 3: Real-time detection of stress and strain data at the stress-bearing part of the casing. When it is detected that the stress and strain data begin to decrease, it indicates that cracks begin to form at the root of the casing thread and both ends of the casing coupling begin to bend. The axial compression force, longitudinal bending force and bending deflection of the casing in this state are recorded to obtain the critical data of casing bending instability in this state. Step 4: Change the initial value of the axial compression force and the initial value of the longitudinal bending force, and change the process value of each increase in the axial compression force and the process value of the longitudinal bending force. Repeat this process many times to obtain the axial compression force, longitudinal bending force and bending deflection of the casing under various states, and then obtain the critical data of casing bending instability under various states.

2. The experimental method for preventing casing bending instability according to claim 1 is characterized in that: The axial compressive force and the longitudinal bending force applied in step 1 may be the same or different.

3. The experimental method for preventing casing bending instability according to claim 1 is characterized in that: The axial compressive force in step 2 is increased by 5-10 tons each time.

4. The experimental method for preventing casing bending instability according to claim 1 is characterized in that: The longitudinal bending force increased each time in step 5 is 1-5 tons.

5. The experimental method for preventing casing bending instability according to claim 1 is characterized in that: The setting time in step 2 is 3-5 minutes.

6. The experimental method for preventing casing bending instability according to claim 1 is characterized in that: In step 3, stress strain gauges are used to detect stress and strain data at the casing end and casing coupling respectively.

7. Experimental device for preventing casing from bending and instability, characterized by include: A base, used for horizontally placing a casing string to be tested formed by connecting two casings through a casing coupling; A longitudinal hydraulic cylinder, fixed in the middle of the base, is used to apply an upward longitudinal bending force to the casing coupling of the casing string; An axial hydraulic cylinder, disposed at the end of the casing string, for applying an axial compression force to the other end of the casing string; A hydraulic pump, used to control the longitudinal hydraulic cylinder and the axial hydraulic cylinder respectively through hydraulic pipelines; Stress strain gauges are fixed between the longitudinal hydraulic cylinder and the casing string and between the axial hydraulic cylinder and the casing string, respectively, and are used to detect stress and strain data at the stress-bearing part of the casing string; The multifunctional display is connected to the hydraulic pump and the stress strain gauge respectively, and is used to record and display the axial compression force, longitudinal bending force and stress strain data.

8. The experimental device for preventing casing from bending instability according to claim 7 is characterized in that: The base includes a transverse seat and a vertical seat, the vertical seats are symmetrically fixed at both ends of the transverse seat, one end of the casing string can move through one of the vertical seats and then abut against the other vertical seat; the longitudinal hydraulic cylinder is fixed under the casing coupling through the transverse seat, and the axial hydraulic cylinder is fixed to the other end of the casing string through the transverse seat.

9. A storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the experimental method for preventing casing bending instability according to any one of claims 1 to 6 is implemented.

10. A processor, the processor being used to run a program, characterized in that: When the program is running, the experimental method for preventing casing bending instability described in any one of claims 1 to 6 is executed.

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