Asymmetric sealing element for packer and optimization method thereof

Abstract

The invention relates to an asymmetric sealing element for a packer and an optimization method of the asymmetric sealing element, and relates to the field of drilling engineering technologies and equipment, the wall thickness of one end of the asymmetric sealing element is larger than that of the other end of the asymmetric sealing element, and one end of the asymmetric sealing element is used for facing a fixed end of a setting mechanism. According to the optimization method, a finite element simulation method is used for simulating the stress condition of the asymmetric sealing element in the setting process and after setting. The method has the advantages that the structural size of the sealing element is optimized through a finite element simulation analysis method, and optimal structural parameters can be found conveniently. By changing the element structure and optimizing the deformation process, the packer has higher pressure resistance. And the optimized structure does not change the setting process and the structural shape of the setting mechanism, and the universality is high.

Description

Technical Field

[0001] This invention relates to the field of drilling engineering technology and equipment, specifically to an asymmetric sealing element for packers and its optimization method. Background Technology

[0002] Packers are important tools widely used in drilling and completion operations. Their main function is to isolate the annular space above and below the packer, such as the gap between the tubing and the casing or open hole wall of the oil and gas well, so as to isolate gas and liquid.

[0003] The sealing element is the component in the packer that directly impedes gas and liquid, thus achieving an isolation effect. Sealing elements are typically made of rubber, but some are made of metal to improve temperature resistance. During the operation of a compression packer, after the packer is lowered to the designated position, axial pressure is applied by the setting mechanism, causing the sealing element to compress and deform, increasing its lateral dimension to fill the annular space and achieve the sealing effect.

[0004] One of the key performance indicators of a packer is its pressure resistance, which is the differential pressure it can withstand without leakage. Due to the increasing demand for deep oil and gas resource development in my country, the high-pressure environment in deep and ultra-deep wells places higher demands on the pressure resistance of packers. The structure of the sealing element directly affects its deformation process during the setting stage, thus affecting the sealing state and pressure resistance after setting. If the structural design of the sealing element is unreasonable, poor adhesion between the element and the inner / outer wall of the annular space may occur after setting, leading to leakage when subjected to differential pressure. Therefore, improving the deformation state of the sealing element after setting is an important means to enhance the pressure resistance of the packer.

[0005] Currently, in compression packers, the sealing element is fixed at one end during the setting process, while the other end is compressed and deformed by the setting mechanism to complete the setting. Due to contact friction, the load on the sealing element during the setting process is asymmetrical. Therefore, traditional symmetrical sealing elements (such as the rubber sleeve structure of the compression packer in patent CN201720936206.4) deform unevenly during the setting process, which can easily lead to poor contact between the sealing element and the inner and outer walls of the annulus after setting, making leakage more likely under pressure. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to improve the compressive strength of packers.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: an asymmetric sealing element for a packer, the asymmetric sealing element is cylindrical, the wall thickness of one end of the asymmetric sealing element is greater than the wall thickness of the other end, and one end of the asymmetric sealing element is used to face the fixed end of the setting mechanism.

[0008] The beneficial effects of this invention are as follows: The asymmetric sealing element adopts an asymmetric structure with different thicknesses at both ends, which can effectively improve the contact state between the asymmetric sealing element and the inner and outer walls, balance the contact forces at both ends of the asymmetric sealing element, reduce the setting force during the setting process, give the packer greater compressive strength, and improve the performance of the packer. The designed structure is easy to implement, does not affect other structures of the packer, and does not change the setting process of the packer, thus having high practicality and can be widely used in packers of different sizes.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, the inner wall of the asymmetric sealing element is a cylindrical hole.

[0011] The beneficial effect of adopting the above-mentioned further solution is that the inner wall of the asymmetric sealing element is used to fit on the outside of the cylindrical central tube.

[0012] Furthermore, the generatrix of the outer wall of the asymmetric sealing element is a straight line, a convex curve, or a multi-segment broken line.

[0013] Furthermore, the inner wall of the asymmetric sealing element has a groove formed along its circumference.

[0014] The beneficial effect of adopting the above-mentioned further scheme is that during the process of axial compression and radial expansion of the compression packer, the middle part of the asymmetric sealing element bulges outward radially from the groove position. The position of the bulge can be controlled by the position of the groove, thereby improving the contact state between the asymmetric sealing element and the inner and outer walls after setting.

[0015] Furthermore, the groove is located in the middle of the axial direction of the asymmetric sealing element and is biased towards one end of the asymmetric sealing element.

[0016] The beneficial effect of adopting the above-mentioned further solution is that the groove is set at one end biased towards the asymmetric sealing element, that is, towards the fixed end of the setting mechanism, so that the load on both ends of the asymmetric sealing element is symmetrical, and the packer has greater compressive strength.

[0017] Furthermore, both ends of the outer wall of the asymmetric sealing element have frustum surfaces, and the diameter of the frustum surfaces gradually decreases from the middle of the asymmetric sealing element to its ends.

[0018] The beneficial effects of adopting the above-mentioned further solution are: the frustum surface and the packer's support ring play a fixing role, and the entire asymmetric sealing element is wrapped by the support ring, which can improve the "shoulder protrusion" (the asymmetric sealing element being squeezed into the gap between the packer and the outer casing or well wall) during the compression process.

[0019] Furthermore, the asymmetric sealing element is made of rubber.

[0020] The present invention also provides an optimization method for an asymmetric sealing element for a packer, for optimizing the structure of an asymmetric sealing element for a packer as described above, comprising the following steps:

[0021] Step 101: Obtain the initial geometric parameters and initial material parameters of the asymmetric sealing element;

[0022] Step 102: Construct the initial finite element model of the asymmetric sealing element based on the initial geometric parameters and the initial material parameters;

[0023] Step 103: Simulate the deformation process of the initial finite element model during the setting process using the finite element simulation method. After setting is completed, extract the contact force distribution data of the inner and outer walls of the initial finite element model.

[0024] Step 104: Based on the contact force distribution data, adjust the initial geometric parameters and the initial material parameters to obtain new geometric parameters and new material parameters;

[0025] Step 200: Manufacture the asymmetric sealing element according to the new geometric parameters and the new material parameters.

[0026] The beneficial effects are: by using the finite element simulation method, the deformation process and the stress situation after setting can be simulated and calculated. Based on the simulation results, the geometric and material parameters of the asymmetric sealing element can be optimized, thereby optimizing the deformation process during setting and the deformation state when setting is completed, improving the contact state between the asymmetric sealing element and the inner / outer wall of the annulus, and thus improving the compressive strength of the packer.

[0027] Furthermore, after step 104, the method further includes step 105, which involves using the new geometric parameters and the new material parameters as the initial geometric parameters and the initial material parameters in step 102, and repeating steps 102 and 104 until the contact force distribution data meets the design requirements.

[0028] The beneficial effect of adopting the above-mentioned further solution is that the parameters of the asymmetric sealing element are repeatedly adjusted until the contact state is optimal, that is, the contact force distribution of the asymmetric sealing element is uniform.

[0029] Furthermore, step 104 specifically includes: when the contact force distribution data shows that the contact force distribution is uneven:

[0030] If the contact force at one end of the initial finite element model is greater than that at the other end, then the wall thickness at one end of the initial finite element model is reduced, the wall thickness at the other end of the initial finite element model is increased, and the position of the groove on the inner wall of the initial finite element model is moved toward the other end of the initial finite element model.

[0031] If the contact force at one end of the initial finite element model is less than that at the other end, then increase the wall thickness at one end of the initial finite element model, decrease the wall thickness at the other end of the initial finite element model, and move the position of the groove on the inner wall of the initial finite element model toward one end of the initial finite element model.

[0032] The advantages of the asymmetric sealing element for packers of the present invention are as follows:

[0033] 1. Optimize the structural dimensions of sealing elements through finite element simulation analysis to easily find the optimal structural parameters.

[0034] 2. By changing the component structure and optimizing the deformation process, the packer can have greater compressive strength.

[0035] 3. The optimized structure does not change the setting process or structural shape of the setting mechanism, and has strong versatility. Attached Figure Description

[0036] Figure 1 This is a half-sectional view of an asymmetric sealing element for a packer according to the present invention;

[0037] Figure 2 A schematic diagram of a packer using the asymmetric sealing element of the present invention;

[0038] Figure 3 This is a simulation diagram of the setting process of the asymmetric sealing element of the present invention;

[0039] Figure 4 A schematic diagram of the structure that generates a shoulder protrusion for the sealing element;

[0040] Figure 5 This is a flowchart of an optimization method for an asymmetric sealing element used in a packer according to the present invention;

[0041] Figure 6 This is a flowchart illustrating a specific method for optimizing an asymmetric sealing element for a packer according to the present invention.

[0042] The attached diagram lists the components represented by each number as follows:

[0043] 1. Fixed end rubber barrel seat; 2. Rear support ring; 3. Rear rubber barrel; 4. Asymmetric sealing element; 41. Busbar; 42. Groove; 43. Frustum; 5. Front rubber barrel; 6. Front support ring; 7. Moving end rubber barrel seat; 8. Center tube. Detailed Implementation

[0044] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0045] Example 1

[0046] like Figures 1-3 As shown, this embodiment provides an asymmetric sealing element for a packer. The asymmetric sealing element 4 is cylindrical, and the wall thickness of one end of the asymmetric sealing element 4 is greater than the wall thickness of the other end. One end of the asymmetric sealing element 4 is used to face the fixed end of the setting mechanism.

[0047] The asymmetric sealing element 4 employs an asymmetric structure with different thicknesses at both ends. This effectively improves the contact state between the asymmetric sealing element 4 and the inner and outer walls, balances the contact forces at both ends of the asymmetric sealing element 4, reduces the setting force during the setting process, and gives the packer greater compressive strength, thus improving its performance. The designed structure is easy to implement, does not affect other structures of the packer, and does not change the setting process flow, making it highly practical and widely applicable to packers of different sizes.

[0048] Specifically, in this embodiment, the wall thickness of the asymmetric sealing element 4 gradually increases along the setting direction, that is, the thickness is smaller near the moving end of the setting mechanism and larger near the fixed end of the setting mechanism.

[0049] by Figure 2 Taking the packer shown as an example, the setting mechanism includes a fixed-end rubber barrel seat 1 and a moving-end rubber barrel seat 7. The fixed-end rubber barrel seat 1 is the fixed end of the setting mechanism, and the moving-end rubber barrel seat 7 is the moving end. The fixed-end rubber barrel seat 1, rear support ring 2, rear rubber barrel 3, asymmetric sealing element 4, front rubber barrel 5, front support ring 6, and moving-end rubber barrel seat 7 are sequentially fitted around the outside of the central tube 8. The fixed-end rubber barrel seat 1 is fixedly installed. During the setting process, the moving-end rubber barrel seat 7 moves towards the fixed-end rubber barrel seat 1, causing the asymmetric sealing element 4 to expand under pressure and seal against the outer wellbore or casing. It should be noted that, since this invention aims to protect the asymmetric sealing element, it can be used with various other compression packers (e.g., using multiple rear rubber barrels 3 and multiple front rubber barrels 5 in series, or using V-shaped rubber barrels at the upper and lower ends, etc.). Figure 2 The example of a simple packer setting mechanism is used to illustrate the working process of the sealing element and should not be construed as limiting the scope of application of this invention.

[0050] Based on the above technical solution, the inner wall of the asymmetric sealing element 4 is a cylindrical hole.

[0051] The inner wall of the asymmetric sealing element 4 is used to fit onto the outer side of the cylindrical central tube 8.

[0052] Based on the above technical solution, the generatrix 41 of the outer wall of the asymmetric sealing element 4 is a straight line, an outwardly convex curve, or a multi-segment broken line.

[0053] Specifically, when the busbar 41 of the outer wall of the asymmetric sealing element 4 is a multi-segment broken line, the multi-segment broken lines are connected by rounded corners.

[0054] Based on the above technical solution, the inner wall of the asymmetric sealing element 4 has a groove 42 opened along its circumference.

[0055] During the process of axial compression and radial expansion of the compression packer, the middle part of the asymmetric sealing element 4 bulges outward radially from the groove 42. The position of the bulge can be controlled by the position of the groove 42, thereby improving the contact state between the asymmetric sealing element 4 and the inner and outer walls after setting.

[0056] Specifically, groove 42 is an annular groove with a circular arc cross-section, or an annular groove with a cross-section of other shapes.

[0057] Based on the above technical solution, the groove 42 is located in the middle of the axial direction of the asymmetric sealing element 4 and is biased towards one end of the asymmetric sealing element 4.

[0058] The groove 42 is located at one end biased towards the asymmetric sealing element 4, that is, towards the fixed end of the setting mechanism, so that the load on both ends of the asymmetric sealing element 4 is symmetrical, and the packer has greater compressive strength.

[0059] Specifically, the groove 42 is set towards the fixed end of the sealing mechanism.

[0060] Based on the above technical solution, both ends of the outer wall of the asymmetric sealing element 4 have frustum surfaces 43, and the diameter of the frustum surfaces 43 gradually decreases from the middle of the asymmetric sealing element 4 to its ends.

[0061] The frustum surface 43, in conjunction with the packer's support ring, serves a fixing function. The entire asymmetric sealing element 4 is enclosed by the support ring, which can improve the "shoulder protrusion" (e.g., during compression) Figure 4 As shown, the shoulder protrusion indicates a situation where an asymmetric sealing element is squeezed into the gap between the packer and the outer casing or wellbore.

[0062] Based on the above technical solution, the asymmetric sealing element 4 is made of rubber.

[0063] Alternatively, the asymmetric sealing element 4 can also be made of other elastic materials that can achieve a sealing effect.

[0064] Example 2

[0065] like Figure 5As shown, this embodiment provides an optimization method for an asymmetric sealing element for a packer, used to optimize the structure of an asymmetric sealing element for a packer as described in Embodiment 1, including the following steps:

[0066] Step 101: Obtain the initial geometric parameters and initial material parameters of the asymmetric sealing element 4;

[0067] Step 102: Construct the initial finite element model of the asymmetric sealing element 4 based on the initial geometric parameters and the initial material parameters;

[0068] Step 103: Simulate the deformation process of the initial finite element model during the setting process using the finite element simulation method. After setting is completed, extract the contact force distribution data of the inner and outer walls of the initial finite element model.

[0069] Step 104: Based on the contact force distribution data, adjust the initial geometric parameters and the initial material parameters to obtain new geometric parameters and new material parameters;

[0070] Step 200: Based on the new geometric parameters and the new material parameters, manufacture the asymmetric sealing element 4.

[0071] The beneficial effects of the above optimization method are as follows: by using the finite element simulation method, the deformation process and the stress situation after setting are simulated and calculated. Based on the simulation results, the geometric parameters and material parameters of the asymmetric sealing element 4 are optimized, thereby optimizing the deformation process during setting and the deformation state when setting is completed. This improves the contact state between the asymmetric sealing element 4 and the inner / outer wall of the annulus (the asymmetric sealing element 4 and the inner central tube 8 and the outer casing or well wall), thereby improving the packer's compressive strength.

[0072] The geometric parameters include the generatrix shape of the asymmetric sealing element 4, the angle between the generatrix and the axis, the inner and outer diameters at both ends, and the relative position of the groove 42 in the axial direction of the asymmetric sealing element 4. The material parameters include the composition, proportions, and elastic modulus of the material of the asymmetric sealing element 4.

[0073] Based on the above methods, such as Figure 6 As shown, after step 104, the method further includes step 105, which uses the new geometric parameters and the new material parameters as the initial geometric parameters and the initial material parameters in step 102, and repeats steps 102 and 104 until the contact force distribution data meets the design requirements.

[0074] In this method, the parameters of the asymmetric sealing element 4 are repeatedly adjusted until the contact state is optimal, that is, the contact force distribution of the asymmetric sealing element 4 is uniform.

[0075] Specifically, contact force distribution data meeting design requirements means that the contact force distribution in the initial finite element model is uniform.

[0076] If the contact force distribution data meets the design requirements after one adjustment in step 104, then step 105 can be skipped.

[0077] Based on the above method, step 104 specifically includes: when the contact force distribution data shows that the contact force distribution is uneven:

[0078] If the contact force at one end of the initial finite element model is greater than that at the other end, then the wall thickness at one end of the initial finite element model is reduced, the wall thickness at the other end of the initial finite element model is increased, and the position of the groove 42 on the inner wall of the initial finite element model is moved toward the other end of the initial finite element model.

[0079] If the contact force at one end of the initial finite element model is less than that at the other end, then the wall thickness at one end of the initial finite element model is increased, the wall thickness at the other end of the initial finite element model is decreased, and the position of the groove 42 on the inner wall of the initial finite element model is moved toward one end of the initial finite element model.

[0080] In other words, if the initial finite element model has a high contact force near the fixed end of the setting mechanism and a low contact force near the moving end, then the outer contour shape is adjusted by reducing the thickness of the initial finite element model near the fixed end and increasing the thickness of the initial finite element model near the moving end, and the position of groove 42 is moved towards the moving end. Conversely, if the initial finite element model has a low contact force near the fixed end of the setting mechanism and a high contact force near the moving end, then the thickness of the initial finite element model near the fixed end is increased, its thickness near the moving end is decreased, and the position of groove 42 is moved towards the fixed end.

[0081] In one specific example, an optimization method for an asymmetric sealing element of a packer includes the following steps:

[0082] Step 101: Obtain the initial geometric parameters and initial material parameters of the asymmetric sealing element.

[0083] Step 102: Construct the initial finite element model of the asymmetric sealing element based on the initial geometric parameters and the initial material parameters.

[0084] Step 103: Simulate the deformation process of the initial finite element model during the setting process using the finite element simulation method. After setting is completed, extract the contact force distribution data of the inner and outer walls of the initial finite element model.

[0085] Step 104: Adjust the initial geometric parameters according to the contact force distribution data to obtain new geometric parameters;

[0086] Specifically, the initial geometric parameters include the wall thicknesses at both ends of the initial finite element model and the relative position of the groove 42 along the axial direction of the asymmetric sealing element 4. When the contact force distribution data shows that the contact force distribution is uneven:

[0087] If the contact force at one end of the initial finite element model is greater than that at the other end, then the wall thickness at one end of the initial finite element model is reduced, the wall thickness at the other end of the initial finite element model is increased, and the position of the groove 42 on the inner wall of the initial finite element model is moved toward the other end of the initial finite element model.

[0088] If the contact force at one end of the initial finite element model is less than that at the other end, then the wall thickness at one end of the initial finite element model is increased, the wall thickness at the other end of the initial finite element model is decreased, and the position of the groove 42 on the inner wall of the initial finite element model is moved toward one end of the initial finite element model.

[0089] Step 105: Use the new geometric parameters as the initial geometric parameters in step 102, and repeat steps 102 and 104 until the contact force distribution data meets the design requirements.

[0090] Step 200: Manufacture the asymmetric sealing element according to the new geometric parameters.

[0091] It should be noted that in the specific example above, only the geometric parameters of the asymmetric sealing element were adjusted. In other examples, the material parameters of the asymmetric sealing element can also be adjusted at the same time to achieve a better setting effect.

[0092] In the description of this invention, it should be noted that the terms "thickness", "upper", "lower", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0093] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0094] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0095] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An asymmetric sealing element for a packer, characterized in that, The asymmetric sealing element (4) is cylindrical, and the wall thickness of one end of the asymmetric sealing element (4) is greater than the wall thickness of the other end. One end of the asymmetric sealing element (4) is used to face the fixed end of the setting mechanism.

2. The asymmetric sealing element for a packer according to claim 1, characterized in that, The inner wall of the asymmetric sealing element (4) is a cylindrical hole.

3. An asymmetric sealing element for a packer according to claim 2, characterized in that, The generatrix (41) of the outer wall of the asymmetric sealing element (4) is a straight line, a convex curve, or a multi-segment broken line.

4. An asymmetric sealing element for a packer according to claim 1, characterized in that, The inner wall of the asymmetric sealing element (4) has a groove (42) opened along its circumference.

5. An asymmetric sealing element for a packer according to claim 4, characterized in that, The groove (42) is located in the middle of the axial direction of the asymmetric sealing element (4) and is biased towards one end of the asymmetric sealing element (4).

6. An asymmetric sealing element for a packer according to claim 1, characterized in that, The outer wall of the asymmetric sealing element (4) has a frustum (43) at both ends, and the diameter of the frustum (43) gradually decreases from the middle of the asymmetric sealing element (4) to its ends.

7. An asymmetric sealing element for a packer according to any one of claims 1-6, characterized in that, The asymmetric sealing element (4) is made of rubber.

8. An optimization method for an asymmetric sealing element used in a packer, characterized in that, To optimize the structure of an asymmetric sealing element for a packer as described in any one of claims 1-7, the following steps are included: Step 101: Obtain the initial geometric parameters and initial material parameters of the asymmetric sealing element (4); Step 102: Construct the initial finite element model of the asymmetric sealing element (4) based on the initial geometric parameters and the initial material parameters; Step 103: Simulate the deformation process of the initial finite element model during the setting process using the finite element simulation method. After setting is completed, extract the contact force distribution data of the inner and outer walls of the initial finite element model. Step 104: Based on the contact force distribution data, adjust the initial geometric parameters and the initial material parameters to obtain new geometric parameters and new material parameters; Step 200: Based on the new geometric parameters and the new material parameters, manufacture the asymmetric sealing element (4).

9. The method for optimizing an asymmetric sealing element for a packer according to claim 8, characterized in that, The step 104 is followed by step 105, which involves using the new geometric parameters and the new material parameters as the initial geometric parameters and the initial material parameters in step 102, and repeating steps 102 and 104 until the contact force distribution data meets the design requirements.

10. The method for optimizing an asymmetric sealing element for a packer according to claim 8, characterized in that, Step 104 specifically includes: when the contact force distribution data shows that the contact force distribution is uneven: If the contact force at one end of the initial finite element model is greater than that at the other end, then the wall thickness at one end of the initial finite element model is reduced, the wall thickness at the other end of the initial finite element model is increased, and the position of the groove (42) on the inner wall of the initial finite element model is moved toward the other end of the initial finite element model. If the contact force at one end of the initial finite element model is less than that at the other end, then increase the wall thickness at one end of the initial finite element model, decrease the wall thickness at the other end of the initial finite element model, and move the position of the groove (42) on the inner wall of the initial finite element model toward one end of the initial finite element model.

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