Design method of elastic ball seat

Abstract

The present invention provides a design method for an elastic ball seat. The design method for the elastic ball seat includes: obtaining the initially determined parameter values of the elastic ball seat, where the initially determined parameter values include a basic parameter group, a first parameter group, a second parameter group, and a third parameter group; determining the target value of the first parameter group according to the relationship between the actual strength and the material strength; determining the target value of the second parameter group according to the passing condition of the elastic ball seat through the sliding sleeve; and determining the target value of the third parameter group according to the positioning condition of the elastic ball seat for clamping the sliding sleeve. Through the technical solution provided by the present application, the problem that the structure of the elastic ball seat in the prior art is unreasonable and affects the opening accuracy of the sliding sleeve can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield production, and more particularly, to a design method for an elastic ball seat. Background Art

[0002] In order to improve the efficiency of the infinite-stage pressure division operation of the cementing sliding sleeve and reduce the operation cost, technicians hope to complete the operation of opening the sliding sleeve only by putting corresponding tools at the wellhead without relying on ground supporting equipment such as coiled tubing trucks. Currently, there are the following types of related technologies:

[0003] Finite-stage ball-drop cementing sliding sleeve pressure division. This technology can perform fracturing by successively dropping fracturing balls with a certain stage difference from the wellhead to open the downhole sliding sleeves in sequence.

[0004] Infinite-stage ball-drop cementing sliding sleeve pressure division. The internal of the sliding sleeve of this technology has a counting device, which allows fracturing balls with the same set quantity and size to be used, realizing the function of infinite-stage ball-drop fracturing.

[0005] Dart-drop infinite-stage cementing sliding sleeve pressure division. This technology can perform fracturing by successively opening the downhole sliding sleeves by dropping darts of the same size from the wellhead.

[0006] There is also a method that uses an elastic ball seat with elasticity and can be contracted under external force to successively open the downhole sliding sleeves for fracturing. However, the structure of this elastic ball seat is often not easy to match with the downhole sliding sleeve, affecting the accuracy of opening the sliding sleeve. Summary of the Invention

[0007] The present invention provides a design method for an elastic ball seat to solve the problem that the structure of the elastic ball seat in the prior art is unreasonable and affects the accuracy of opening the sliding sleeve.

[0008] The present invention provides a design method for an elastic ball seat, and the design method for the elastic ball seat includes:

[0009] Obtain the initial parameter values of the elastic ball seat, where the initial parameter values include a basic parameter group, a first parameter group, a second parameter group, and a third parameter group;

[0010] Determine the target value of the first parameter group according to the relationship between the actual strength and the material strength;

[0011] Determine the target value of the second parameter group according to the passing condition of the elastic ball seat through the sliding sleeve;

[0012] Determine the target value of the third parameter group according to the positioning condition of the elastic ball seat for clamping the sliding sleeve;

[0013] Among them, the basic parameter group includes D, d, a, μ, E, and P. D is the maximum outer diameter of the ball seat step, d is the maximum outer diameter of the ball seat body, a is the effective cantilever length, μ is the friction coefficient, E is the elastic modulus of the material, and P is the liquid pressure;

[0014] The first parameter group includes b, h, and n. b is the width of the elastic claw body, h is the wall thickness of the elastic claw body, and n is the number of elastic claws;

[0015] The second parameter group includes α1, L max , α1 is the minimum value of the step angle formed at the variable inner diameter of the pipe string, and L max is the maximum value of the total slotting length;

[0016] The third parameter group includes α2, L min , α2 is the maximum value of the step angle formed at the variable inner diameter of the pipe string, and L min is the minimum value of the total slotting length.

[0017] Furthermore, according to the relationship between the actual strength and the material strength, the target values of the first parameter group are determined, specifically including:

[0018] Obtain the actual stress value according to the first parameter group;

[0019] Judge whether the actual stress value obtained from the first parameter group satisfies:

[0020] σ1 < [σ] Formula 1;

[0021] If not, adjust the parameters in the first parameter group to make it satisfy Formula 1, where σ1 is the actual stress value and [σ] is the allowable stress of the material.

[0022] Furthermore, according to the passing condition of the elastic ball seat through the sliding sleeve, the target values of the second parameter group are determined, specifically including:

[0023] Judge whether the initially determined parameter values satisfy:

[0024]

[0025] If not, adjust the parameters in the second parameter group to make the initially determined parameter values satisfy Formula 2.

[0026] Furthermore, according to the positioning condition of the elastic ball seat clamping the sliding sleeve, the target values of the third parameter group are determined, specifically including:

[0027] Judge whether the initially determined parameter values satisfy:

[0028]

[0029] If not satisfied, adjust the parameters in the third parameter group to make the initially determined parameter values satisfy Formula 3.

[0030] Further, the initially determined parameter values further include a fourth parameter group. After determining the target values of the third parameter group according to the positioning conditions of the elastic ball seat engaging with the sliding sleeve, the design method further includes:

[0031] Determine the target values of the fourth parameter group according to the identification conditions of the elastic ball seat matching the sliding sleeve;

[0032] Among them, the parameters of the first parameter group are the same as those of the fourth parameter group.

[0033] Further, determining the target values of the fourth parameter group according to the identification conditions of the elastic ball seat matching the sliding sleeve specifically includes:

[0034] Obtain S according to the fourth parameter group, where S is the actual contact area between the elastic ball seat and the sliding sleeve;

[0035] Judge whether the initially determined parameter values and S satisfy:

[0036]

[0037] If not satisfied, adjust the parameters in the fourth parameter group to make the initially determined parameter values satisfy Formula 4.

[0038] Applying the technical solution of the present invention, when designing the parameters of the elastic ball seat, first initially determine the parameter values, and then determine the target values of the first parameter group through the relationship between the actual strength and the material strength; determine the target values of the second parameter group according to the passing conditions of the elastic ball seat through the sliding sleeve, and determine the target values of the third parameter group according to the positioning conditions of the elastic ball seat engaging with the sliding sleeve. The parameter values obtained by this design method can make the strength of the elastic ball seat meet the use requirements, and enable the elastic ball seat to directly pass through the sliding sleeve that does not match it and engage with the corresponding step position of the sliding sleeve when falling into the step position of the corresponding sliding sleeve. This can improve the accuracy of the elastic ball seat size design, ensure the matching of the elastic ball seat size and the sliding sleeve step size, and improve the accuracy of the sliding sleeve opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 Shows a schematic structural diagram of an elastic ball seat provided according to an embodiment of the present invention;

[0041] Figure 2 Shows the force analysis diagram of the elastic ball seat passing through the sliding sleeve step. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation on the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] As Figure 1 and Figure 2 shown, the embodiments of the present invention provide a design method for an elastic ball seat, and the design method for the elastic ball seat includes:

[0044] Step 1, obtain the initial parameter values of the elastic ball seat, and the initial parameter values include a basic parameter group, a first parameter group, a second parameter group, and a third parameter group;

[0045] Step 2, determine the target value of the first parameter group according to the relationship between the actual strength and the material strength;

[0046] Step 3, determine the target value of the second parameter group according to the passing condition of the elastic ball seat through the sliding sleeve;

[0047] Step 4, determine the target value of the third parameter group according to the positioning condition of the elastic ball seat clamping the sliding sleeve;

[0048] Among them, the elastic ball seat realizes elastic deformation by grooving on the metal cylinder, and its mechanical model is a cantilever beam. Therefore, the size of the elastic ball seat can be designed and determined by referring to the cantilever beam. Among them, in Figure 2 , Fx is the axial load received by the elastic ball seat, f is the frictional force received by the elastic ball seat when passing through the step of the sliding sleeve, N is the normal pressure on the contact surface between the step of the sliding sleeve and the elastic ball seat, and α is the step angle formed at the variable inner diameter of the pipe string. The basic parameter group includes D, d, a, μ, E, and P, where D is the maximum outer diameter of the ball seat step, d is the maximum outer diameter of the ball seat body, a is the effective cantilever length, μ is the friction coefficient, E is the material elastic modulus, and P is the liquid pressure;

[0049] The first parameter group includes b, h, and n, where b is the width of the elastic claw body, h is the wall thickness of the elastic claw body, and n is the number of elastic claws;

[0050] The second parameter group includes α1, L max , α1 is the minimum value of the step angle formed at the variable inner diameter of the pipe string, and L max is the maximum value of the total grooving length;

[0051] The third parameter group includes α2, Lmin , α2 is the maximum value of the step angle formed at the variable inner diameter of the pipe string, and L min is the minimum value of the total slot length.

[0052] Through the technical solution provided by this embodiment, when designing the parameters of the elastic ball seat, first initially determine the parameter values, and then determine the target values of the first parameter group based on the relationship between the actual strength and the material strength. According to the passing condition of the elastic ball seat through the sliding sleeve, determine the target values of the second parameter group so that the elastic ball seat can pass through the sliding sleeve step that does not match it. According to the positioning condition of the elastic ball seat clamping the sliding sleeve, determine the target values of the third parameter group so that when the elastic ball seat falls into the sliding sleeve step that matches it, it clamps with this step. The parameter values obtained through this design method can make the strength of the elastic ball seat meet the usage requirements, and enable the elastic ball seat to directly pass through the sliding sleeve step that does not match it and clamp with the step when falling into the corresponding sliding sleeve step position. This can improve the accuracy of the elastic ball seat size design, ensure that the elastic ball seat size matches the inner step size of the sliding sleeve, and improve the opening efficiency of the sliding sleeve.

[0053] Specifically, when performing step 2, determining the target values of the first parameter group according to the relationship between the actual strength and the material strength specifically includes:

[0054] Obtain the actual stress value according to the first parameter group. This actual stress value can be calculated according to existing formulas or obtained through software calculation.

[0055] Judge whether the actual stress value obtained from the first parameter group satisfies:

[0056] σ1 < [σ] Formula 1;

[0057] If the first parameter group does not satisfy the above Formula 1, then adjust the values of the first parameter group. Specifically, the adjustment can be made by increasing the b value and / or decreasing the h value and / or decreasing the n value. If it satisfies Formula 1, no adjustment is required. Among them, σ1 is the actual stress value, and [σ] is the allowable stress of the material.

[0058] Specifically, when performing step 3, determining the target values of the second parameter group according to the passing condition of the elastic ball seat through the sliding sleeve specifically includes:

[0059] Judge whether the initially determined parameter values satisfy:

[0060]

[0061] If not, adjust the parameters within the second parameter group to make the initially determined parameter values satisfy Formula 2. Specifically, the adjustment can be made by reducing α1 and / or reducing L max in this way. If it satisfies, no adjustment is required.

[0062] Specifically, when performing step 4, determine the target value of the third parameter group according to the positioning conditions of the elastic ball seat clamping sliding sleeve, which specifically includes:

[0063] Judge whether the initially determined parameter value satisfies:

[0064]

[0065] If it does not satisfy, adjust the parameters in the third parameter group to make the initially determined parameter value satisfy formula 3. Specifically, it can be adjusted by increasing α2 and / or increasing L min in this way. If it satisfies, no adjustment is needed.

[0066] In this embodiment, the initially determined parameter value further includes a fourth parameter group. After determining the target value of the third parameter group according to the positioning conditions of the elastic ball seat clamping sliding sleeve, this design method further includes:

[0067] Step 5, determine the target value of the fourth parameter group according to the recognition conditions of the elastic ball seat matching sliding sleeve;

[0068] Among them, the parameters of the first parameter group are the same as those of the fourth parameter group. Specifically, this recognition condition can make the elastic ball seat fall into the step of the sliding sleeve that matches it, that is, after putting the elastic ball seat into the casing, only the step of this sliding sleeve can clamp the elastic ball seat, and the elastic ball seat will pass through other sliding sleeve steps before falling into this step. Even if there is a step that can be clamped, it will continue to fall due to the deformation of the elastic ball seat until it falls into the corresponding sliding sleeve step. Through this step, it can be avoided that the elastic ball seat is clamped into the sliding sleeve step that does not match it, and the matching accuracy of the elastic ball seat and the sliding sleeve step is further improved.

[0069] Specifically, when performing step 5, determine the target value of the fourth parameter group according to the recognition conditions of the elastic ball seat matching sliding sleeve, which specifically includes:

[0070] Obtain S according to the fourth parameter group, where S is the actual contact area between the elastic ball seat and the sliding sleeve;

[0071] Judge whether the initially determined parameter value and S satisfy:

[0072]

[0073] If it does not satisfy, adjust the parameters in the fourth parameter group to make the initially determined parameter value satisfy formula 4.

[0074] When adopting the design method provided in this embodiment, it can be executed in the order of steps 1 to 5, or the execution order of the remaining steps can be disrupted after step 1 is executed. In this embodiment, it is executed in the order of step 1, step 2, step 3, step 4, and step 5. And when any one of steps 3, 4, and 5 is executed, if the parameters are adjusted, then return to step 2. If there is no adjustment, continue to execute according to this order of steps. Through this step, the number of adjustments can be reduced and the adjustment efficiency can be improved.

[0075] According to the above design method, specific descriptions will be given in combination with the following embodiments. The specific operations are as follows:

[0076] Step 1, initially set the following parameter values:

[0077] n = 12, L min = 35mm, L max = 200mm, b = 18mm, h = 3mm, D = 120mm, d = 116mm;

[0078] a = 87mm, α1 = 10°, α2 = 75°, μ = 0.1, E = 216000MPa, [σ] = 835MPa,

[0079] P is 50MPa under the strength condition, 3MPa under the passing condition, 50MPa under the positioning condition, and 10MPa under the identification condition.

[0080] Step 2, use the cantilever beam model and substitute the above parameter values to calculate that the actual strength value is 815.04MPa, which is less than the allowable stress value of 835MPa. Therefore, the first parameter group meets the requirements.

[0081] Substitute the above parameter values into the calculation formula of step 3. The value on the left side of the formula is 131300.4N, and the value on the right side of the formula is 176616.5N. Therefore, the second parameter group meets the requirements.

[0082] Substitute the above parameter values into the calculation formula of step 4. The value on the left side of the formula is 376299.6N, and the value on the right side of the formula is 127366.8N. Therefore, the third parameter group meets the requirements.

[0083] Substitute the above parameter values into the calculation formula of step 5. Through analysis and in combination with the calculation formula, it can be concluded that the fourth parameter group meets the requirements.

[0084] Based on the above calculation results, it can be considered that the selected parameter values meet the judgment conditions under the given working condition loads, and the selected parameters are appropriate. After manufacturing according to this size, the elastic ball seat can be tested. The test results show that the elastic ball seat can be clamped into the step of the predetermined sliding sleeve and can withstand the preset load, and it meets the requirements of the use conditions.

[0085] Through the design method provided in this embodiment, the elastic ball seat is deformed, shrunk, and can accurately identify and be reliably positioned with the target structure.

[0086] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0087] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0088] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus cannot be construed as limiting the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0089] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper", etc. can be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures will then be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the corresponding explanations are made for the spatial relative descriptions used herein.

[0090] In addition, it should be noted that the use of terms such as "first" and "second" to define components is only for the convenience of differentiating the corresponding components. Without additional statements, the above terms have no special meanings, and thus should not be construed as limiting the protection scope of the present invention.

[0091] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A design method of an elastic ball seat, characterized in that, The design method of the elastic ball seat includes: Obtaining the preliminary parameter values of the elastic ball seat, where the preliminary parameter values include a basic parameter group, a first parameter group, a second parameter group, and a third parameter group; Determining the target value of the first parameter group according to the relationship between the actual strength and the material strength; Determining the target value of the second parameter group according to the passing condition of the elastic ball seat through the sliding sleeve; Determining the target value of the third parameter group according to the positioning condition of the elastic ball seat clamping the sliding sleeve; Among them, the basic parameter group includes D, d, a, μ, E, and P. D is the maximum outer diameter of the ball seat step, d is the maximum outer diameter of the ball seat body, a is the effective cantilever length, μ is the friction coefficient, E is the material elastic modulus, and P is the liquid pressure; The first parameter group includes b, h, and n. b is the width of the elastic claw body, h is the wall thickness of the elastic claw body, and n is the number of elastic claws; The second parameter group includes α1 and L max , where α1 is the minimum value of the step angle formed at the variable inner diameter of the pipe string, and L max is the maximum value of the total grooving length; The third parameter group includes α2 and L min , where α2 is the maximum value of the step angle formed at the variable inner diameter of the pipe string, and L min is the minimum value of the total slotting length; Determining the target value of the first parameter group according to the relationship between the actual strength and the material strength, specifically including: Obtaining the actual stress value according to the first parameter group; Judging whether the actual stress value obtained by the first parameter group satisfies: σ1 < [σ] Formula 1; If not, adjust the parameters in the first parameter group to make it satisfy Formula 1, where σ1 is the actual stress value and [σ] is the allowable stress of the material; Determining the target value of the second parameter group according to the passing condition of the elastic ball seat through the sliding sleeve, specifically including: Judging whether the preliminary parameter values satisfy: If not, adjust the parameters in the second parameter group to make the preliminary parameter values satisfy Formula 2; Determining the target value of the third parameter group according to the positioning condition of the elastic ball seat clamping the sliding sleeve, specifically including: Judging whether the preliminary parameter values satisfy: If not, adjust the parameters in the third parameter group to make the preliminary parameter values satisfy Formula 3.

2. The design method according to claim 1, characterized in that The preliminary parameter values further include a fourth parameter group. After determining the target value of the third parameter group according to the positioning condition of the elastic ball seat clamping the sliding sleeve, the design method further includes: Determining the target value of the fourth parameter group according to the recognition condition of the elastic ball seat matching the sliding sleeve; Among them, the parameters of the first parameter group are the same as those of the fourth parameter group.

3. The design method according to claim 2, characterized in that, Determining the target value of the fourth parameter group according to the recognition condition of the elastic ball seat matching the sliding sleeve, specifically including: Obtaining S according to the fourth parameter group, where S is the actual contact area between the elastic ball seat and the sliding sleeve; Judging whether the preliminary parameter values and S satisfy: If not, adjust the parameters in the fourth parameter group to make the preliminary parameter values satisfy Formula 4.

Images