A method for determining the tensile strength of high-strength structural screen pipes

Abstract

The present invention belongs to the technical field of strength testing of petroleum pipes, and specifically relates to a method for determining the tensile strength of a high-strength structural screen pipe. The method of the present invention is: first, the connection strength parameters are obtained through experiments; then the circumferential aperture spacing is calculated, and according to the angle between the holes of the axially and circumferentially adjacent cross-sections, the triangle type is determined to calculate the tensile strength of the screen pipe. The present invention is based on the angle between the holes of the axially and circumferentially adjacent cross-sections of the screen pipe, which is divided into obtuse isosceles triangles, right isosceles triangles, equilateral triangles and acute isosceles triangles. For different triangle structures, the connection strength of the screen pipe is established in relation to the opening diameter, axial hole spacing and cross-sectional hole number. This can effectively solve the problem of the inability to determine the tensile strength of the screen pipe, provide a reference for on-site construction, and avoid the occurrence of serious construction safety accidents.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum pipe strength testing and relates to a method for determining the tensile strength of a high-strength structural screen pipe. Background Art

[0002] With the widespread adoption of horizontal openhole screen top cementing completion technology, the use of screen-type sand filters (screens) is increasing. As oil and gas exploration and development progress, drilling conditions and geological conditions become increasingly complex, placing increasing demands on screen strength. Screen damage can severely impact the economic benefits of oilfields.

[0003] The screen consists of a base pipe, inner and outer support meshes, a filter, and an outer protective pipe. The outer protective pipe protects the inner filter, reducing excessive erosion of the filter by fluids and impurities in the wellbore. The outer support mesh provides evenly distributed liquid flow for the filter, which can meet the sand control needs of coarse, medium, and fine particle sizes. The inner support mesh is wrapped around the inner protective pipe and longitudinally welded at the seam. The base pipe is made of API standard casing or tubing and is the basis of the screen's strength. The hole pattern of the base pipe determines the tensile strength of the screen, and the drilling method on the base pipe has a significant impact on its tensile strength. Its failure mechanism is complex. However, due to the wide variety of hole patterns, domestic and international research on screen strength has mainly focused on the evaluation of anti-extrusion strength and sand control and flow performance, while there are relatively few reports on screen tensile strength research. Therefore, there is currently no ready-made method to determine the tensile strength of screens to solve the problem of quantitative analysis of the tensile strength of screens, making it impossible to predict screen failure.

[0004] In summary, filling the gap in the current method for determining the tensile strength of sieve tubes, solving the problem of quantitative analysis of the tensile strength of sieve tubes, and predicting the failure of sieve tubes have become the key research directions of researchers in this field. Summary of the Invention

[0005] The present invention provides a method for determining the tensile strength of a high-strength structural screen pipe, so as to solve the problems in the prior art of being unable to determine the tensile strength of the screen pipe and being unable to predict the failure of the screen.

[0006] In order to achieve the purpose of the present invention, the present invention adopts the following technical solution: a method for determining the tensile strength of a high-strength structural screen pipe, comprising:

[0007] Step 1: Obtain connection strength parameters through experiments;

[0008] Step 2: Calculate the circumferential aperture spacing

[0009] Wherein, n represents the number of cross-sectional holes, and D represents the average outer diameter of the base pipe of the screen pipe;

[0010] Step 3: Calculate the angle between adjacent cross-section holes in the axial and circumferential directions

[0011] Step 4: Calculate the tensile strength of the screen according to the triangle type:

[0012] If the angle α is less than 45°, use the formula:

[0013]

[0014] Among them, F a Indicates the tensile strength of the screen tube; Y t Indicates the tensile strength of the screen material; D indicates the outer diameter of the sample, t indicates the wall thickness of the sample, d indicates the opening diameter, and b indicates the axial hole spacing;

[0015] If the right isosceles triangle with an included angle α greater than or equal to 45° is converted to an equilateral triangle with an included angle α less than or equal to 60°, use the formula

[0016]

[0017] Among them, F a Indicates the tensile strength of the screen tube; Y t Indicates the tensile strength of the screen material; D indicates the outer diameter of the sample, and t indicates the wall thickness of the sample;

[0018] If the angle α is an acute isosceles triangle with an angle greater than 60° and less than 90°, use the formula

[0019]

[0020] Among them, F a Indicates the tensile strength of the screen tube; Y t Indicates the tensile strength of the screen material; D indicates the outer diameter of the sample, and t indicates the wall thickness of the sample;

[0021] Furthermore, in the above step 1, the geometric dimensions of the screen pipes are measured and the material tensile test is performed, and the tensile strength parameters of the screen pipes of the same batch are obtained by statistical analysis methods.

[0022] Furthermore, the above parameters include average outer diameter D, average wall thickness t, material tensile strength Y t , opening diameter d, axial hole spacing b and number of cross-sectional holes n.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention is based on the angle between the holes of adjacent cross-sections in the axial and circumferential directions of the screen pipe, which are divided into obtuse isosceles triangles, right isosceles triangles, equilateral triangles and acute isosceles triangles. For different triangle structures, the relationship between the connection strength of the screen pipe and the opening diameter, axial hole spacing and the number of holes in the cross section is established, and a method for determining the tensile strength of the screen pipe is proposed.

[0025] 2. This method can quickly and efficiently determine the tensile strength of the screen pipe, quantitatively determine the tensile strength of the screen pipe, and to a certain extent predict the service life of the screen, providing a certain reference for on-site construction and avoiding serious construction safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for determining the tensile strength of a screen pipe;

[0027] Figure 2 Schematic diagram of screen tube structure;

[0028] Figure 3 Schematic diagram of screen tube hole distribution. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and examples.

[0030] See also Figure 1 and Figure 2 The present invention provides a method for determining the tensile strength of a high-strength structural screen pipe, comprising the following steps:

[0031] Step 1: Obtain connection strength parameters through experiments;

[0032] Step 2: Calculate the circumferential aperture spacing

[0033] Wherein, n represents the number of cross-sectional holes, and D represents the average outer diameter of the base pipe of the screen pipe;

[0034] Step 3: Calculate the angle between adjacent cross-section holes in the axial and circumferential directions

[0035] Step 4: Calculate the tensile strength of the screen according to the triangle type.

[0036] Specific examples are given below:

[0037] Example 1: Determination of the tensile strength of Ø177.80×9.19mm N80 screen pipe

[0038] Implementation process: ① Obtain the connection strength calculation parameters, the outer diameter of the base pipe of the screen pipe D = 177.80mm, the wall thickness t = 9.19mm, the material tensile strength Y t=758MPa; the hole arrangement method adopts the hole diameter d = 6mm, the axial hole spacing b = 14mm, the cross-sectional hole number n = 12, ② the root calculates the circumferential hole diameter spacing of 47mm; ③ the angle α between adjacent cross-sectional holes in the axial and circumferential directions is calculated to be 31°; ④ if the angle α is an obtuse isosceles triangle with an angle less than 45°, see Figure 3 (1) The tensile strength of the screen tube is calculated using Formula 3:

[0039]

[0040] Example 2: Determination of the tensile strength of Ø177.80×9.19mm N80 screen pipe

[0041] Implementation process: ① Obtain the connection strength calculation parameters, the outer diameter of the base pipe of the screen pipe D = 177.80mm, the wall thickness t = 9.19mm, the material tensile strength Y t =758MPa; the hole arrangement method adopts the hole diameter d = 6mm, the axial hole spacing b = 28mm, the cross-sectional hole number n = 12, ② the root calculates the circumferential hole diameter spacing of 47mm; ③ calculates the angle α between adjacent cross-sectional holes in the axial and circumferential directions = 50° ④ If the angle α is a right-angled isosceles triangle greater than or equal to 45°, see Figure 3 (2) To an equilateral triangle with an angle α less than or equal to 60°, see Figure 3 (3), then use formula 4 to calculate the tensile strength of the screen tube

[0042]

[0043] Example 3: Determination of tensile strength of Ø177.80×9.19mm N80 screen pipe

[0044] Implementation process: ① Obtain the connection strength calculation parameters, the outer diameter of the base pipe of the screen pipe D = 177.80mm, the wall thickness t = 9.19mm, the material tensile strength Y t =758MPa; the hole arrangement method adopts the hole diameter d = 6mm, the axial hole spacing b = 64mm, the cross-sectional hole number n = 12, ② the root calculates the circumferential hole diameter spacing of 47mm; ③ the angle α between adjacent cross-sectional holes in the axial and circumferential directions is calculated to be 70°; ④ if the angle α is an acute isosceles triangle with an angle greater than 60° and less than 90°, see Figure 3 (4), then use Formula 5 Calculate the tensile strength of the screen pipe to be 3957kN:

[0045] Implementation effect: This method is used to determine the tensile strength requirements of a high-strength structural screen tube with a diameter of 177.80×9.19mm and different hole layouts.

[0046] The above description is only the preferred technical method and embodiment of the present invention, and the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can make equivalent replacements or changes according to the technical solution and inventive concept of the present invention within the technical scope of the present invention, and they are all covered by the protection scope of the present invention.

Claims

1. A method for determining the tensile strength of a high-strength structural screen pipe, characterized in that: The following steps are involved: Step 1: Obtain connection strength parameters through experiments; Step 2: Calculate the circumferential aperture spacing Where n represents the number of cross-sectional holes, and D represents the average outer diameter of the base pipe of the screen pipe; Step 3: Calculate the angle between adjacent cross-section holes in the axial and circumferential directions Where b represents the axial hole spacing; Step 4: Calculate the tensile strength of the screen according to the triangle type: If the angle α is less than 45°, use the formula: Among them, F a Indicates the tensile strength of the screen tube; Y t Indicates the tensile strength of the screen material; t indicates the wall thickness of the sample; d is the opening diameter; If the right isosceles triangle with an included angle α greater than or equal to 45° is converted to an equilateral triangle with an included angle α less than or equal to 60°, use the formula If the angle α is an acute isosceles triangle with an angle greater than 60° and less than 90°, use the formula 。 2. The method for determining the tensile strength of a high-strength structural screen pipe according to claim 1, characterized in that: In step 1, the geometric dimensions of the screen pipes are measured and the material tensile test is performed, and the parameters of the tensile strength of the screen pipes in the same batch are obtained through statistical analysis methods.

3. The method for determining the tensile strength of a high-strength structural screen pipe according to claim 2, characterized in that: The parameters include average outer diameter D, average wall thickness t, material tensile strength Y t , opening diameter d, axial hole spacing b and number of cross-sectional holes n.

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