Calculation method of casing windowing window shape

Abstract

The invention discloses a method for calculating the shape of a casing windowing window. The problem that an existing casing damage well multi-stage setting pressure tool cannot meet the fracturing requirements of small well diameter, multiple sections and large sand amount at the same time is mainly solved. The method is characterized by comprising the following steps: S1, taking a longitudinal section of the whipstock through the center line of a cylinder of the whipstock, establishing a rectangular coordinate system on the longitudinal section, taking the center of a sleeve as a coordinate origin O, taking a downward direction along the sleeve as a Y axis, and taking a direction perpendicular to the Y axis as an X axis; s2, setting the projection length x of the inclined plane of the whipstock on the X axis and the projection length y of the inclined plane of the whipstock on the Y axis; and S3, calculating the length L and the width W of the casing window. By calculating the casing windowing window shape, windowing sidetrack drilling site construction can be guided, reasonable sidetrack drilling parameters are guaranteed, and follow-up tools can smoothly pass through conveniently.

Description

Technical Field

[0001] The invention relates to the technical field of oil drilling and production engineering, in particular to a method for calculating the shape of a casing window. Background Art

[0002] The shape of the casing window is the window and its shape that is directionally milled on the casing using a window opening tool during the casing side drilling window opening process. It has a certain length and is generally in the shape of an inverted water drop. Casing window side drilling is a complex process. The understanding and recognition of the window shape and the calculation and description of the casing window shape provide a theoretical analysis method for window design. It is one of the most intuitive means to guide on-site construction and ensure reasonable side drilling parameters. However, there is currently no calculation method for casing window openings, and it can only rely on manual estimation without an accurate understanding of the window shape. Summary of the invention

[0003] In order to overcome the problem that there is currently no method for calculating the shape of a casing window opening, the present invention provides a method for calculating the shape of a casing window opening. By calculating the shape of the casing window opening, on-site construction of side drilling of the window opening can be guided, reasonable side drilling parameters can be ensured, and subsequent tools can pass smoothly.

[0004] The technical solution of the present invention is: a method for calculating the shape of a casing window, characterized by comprising:

[0005] S1. Take a longitudinal section of the whipstock through the center line of the whipstock cylinder, and establish a rectangular coordinate system on this plane, with the center of the casing as the coordinate origin O, the downward direction along the casing as the Y axis, and the direction perpendicular to the Y axis as the X axis;

[0006] S2. Let the projection length of the whipstock slope on the X-axis be x, and the projection length on the Y-axis be y;

[0007] S3, the length L and width W of the casing window are

[0008] 0 / tanγ

[0009]

[0010] Where: D is the inner diameter of the casing; δ is the wall thickness of the casing; d is the outer diameter of the window milling cone; γ is the inclination angle of the whipstock.

[0011] Furthermore, in step S1, it is first assumed that the projection of the milling cone in the horizontal direction during the window opening process is a circle; and it is assumed that the movement direction of the milling cone remains unchanged after the last point of the milling cone leaves the whipstock.

[0012] Further, in step S2, the inner circle equation of the casing is

[0013]

[0014] The projection equation of the milling cone bottom circle is:

[0015]

[0016] Solving the above two equations, we get

[0017]

[0018] Where: a is the distance between the center of the milling cone and the center of the casing O.

[0019] Further, in step 3, let the intersection points of the maximum diameter of the milling cone and the inner wall of the casing be E and F respectively, then the coordinates of point E are

[0020]

[0021] The coordinates of point F are

[0022]

[0023] Then the distance between two points FE is

[0024]

[0025] The distance between the two points FE is the maximum width of the window.

[0026] Furthermore, in step 3, when the milling cone moves from the inner wall of the casing to the outer wall of the casing, the lateral displacement of the milling cone is the displacement Δa of the center line of the milling cone from the initial state to the center line of the casing. Δa is divided into n equal parts, and the size of each equal part is Δy=Δa / n. Corresponding to each equal part, the window width corresponding to the ground casing is a=a0+iΔy, i=0~n; then the window width corresponding to each equal part is

[0027]

[0028] Then the analytical expression of W with respect to x is

[0029]

[0030] Furthermore, in step 3, since the original distance between the center of the casing and the center of the window milling cone is a0=(Dd) / 2,

[0031] but

[0032]

[0033] The present invention has the following beneficial effects: due to the adoption of the above-mentioned scheme, modeling is carried out in the longitudinal and transverse directions of the window, the window size is calculated using the point tracing method, the window shape is drawn, the shape of the casing window is calculated and accurately grasped, and theoretical guidance is provided for the window design. It can guide the on-site construction of the window side drilling, ensure reasonable side drilling parameters, and facilitate the smooth passage of subsequent tools. It is the key to the success of the window side drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the window milling cone operation of the present invention;

[0035] Figure 2 This is the cross section of the window milling cone of the present invention in the working state;

[0036] Figure 3 is a longitudinal cross-sectional view of the window model of the present invention;

[0037] Figure 4 It is a schematic diagram of the window shape of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings:

[0039] A method for calculating the shape of a casing window opening. First, it is assumed that the projection of the cone in the horizontal direction during the window opening process is a circle. After the last point of the milling cone leaves the whipstock, for a certain period of time, the drill pipe above the milling cone is tangent to the whipstock. Assuming that the movement direction of the milling cone remains unchanged, the following is obtained: Figure 1 shown.

[0040] The specific steps include:

[0041] S1. After the milling tool milling cone is lowered into the casing, due to the pressure of the drill pipe, the milling cone will first have a pure advance along the inclined surface of the whipstock, and finally the outer circle of the milling cone will be attached to the inner wall of the casing. Take a longitudinal section of the whipstock through the center line of the cylinder of the whipstock, and establish a rectangular coordinate system on this surface; take the center of the casing as the coordinate origin O, the direction along the casing downward as the Y axis, and the direction perpendicular to the Y axis as the X axis, and the Figure 2 As shown in the figure, O1 is the center of the milling cone when the outer diameter of the milling cone contacts the inner diameter of the casing; O2 is the center of the milling cone when the window width is the largest.

[0042] S2. Assume that the projection length of the bevel on the X-axis is x, and the projection length on the Y-axis is y, then the inner circle equation of the casing is

[0043]

[0044] The projection equation of the milling cone bottom circle is:

[0045]

[0046] Solving the above two equations, we get

[0047]

[0048] Where: D is the inner diameter of the casing; δ is the wall thickness of the casing; d is the outer diameter of the window milling cone; a is the distance from the center of the milling cone to the center of the casing O.

[0049] S3. Assume that the intersection points of the maximum diameter of the milling cone and the inner wall of the casing are E and F respectively, then the coordinates of point E are

[0050]

[0051] The coordinates of point F are

[0052]

[0053] Then the distance between two points FE is

[0054]

[0055] The distance between the two points FE is the maximum width of the window.

[0056] The milling tool mills the casing along the bevel direction, and the bottom circle of the tool has a displacement in the longitudinal and transverse directions from the inner wall of the casing to the outer wall of the casing. The transverse displacement is the displacement Δa of the center line of the milling cone from the initial state to the center line of the casing, and the longitudinal displacement is the length of a window shape. If Δa is divided into n equal parts, the size of each part is Δy=Δa / n. Corresponding to each part, the ground casing must form a local window shape, and the corresponding window width is a=a0+iΔy, i=0~n; the window width corresponding to each part is

[0057]

[0058] Obviously, we can get the function of W about x, and the analytical expression of the function is

[0059]

[0060] Since the original distance between the center of the casing and the center of the window milling cone is a0 = (Dd) / 2, the width W of the window is

[0061]

[0062] Depend on Figure 3 As shown, the length L of the casing window is

[0063] L=d / tanγ

[0064] Where: γ is the inclination angle of the whipstock.

[0065] Divide the opened window length L = d / tanγ into n equal parts, each of which is ΔL = d / (n*tanγ). Then, the window width W corresponding to each part is i Calculate it and draw it on the bisector corresponding to the window length L to get the simulated window shape, which is Figure 4 shown.

[0066] This method models the window in the longitudinal and transverse directions, calculates the window size using the point tracing method, draws the window shape, calculates and accurately grasps the shape of the casing window, provides theoretical guidance for window design, can guide on-site construction of window side drilling, ensure reasonable side drilling parameters, and facilitate the smooth passage of subsequent tools, which is the key to the success of window side drilling.

Claims

1. A method for calculating the shape of a casing window, characterized in that include: S1. Take a longitudinal section of the whipstock through the center line of the whipstock cylinder, and establish a rectangular coordinate system on this plane, with the center of the casing as the coordinate origin O, the downward direction along the casing as the Y axis, and the direction perpendicular to the Y axis as the X axis; S2. Let the projection length of the whipstock slope on the X-axis be x, and the projection length on the Y-axis be y; S3, the length L and width W of the casing window are respectively = 0 / tanγ Where: D is the inner diameter of the casing; δ is the wall thickness of the casing; d is the outer diameter of the window milling cone; γ is the inclination angle of the whipstock.

2. The method for calculating the shape of the casing window opening according to claim 1, characterized in that: In the step S1, it is first assumed that the projection of the milling cone in the horizontal direction during the window opening process is a circle; and it is assumed that the movement direction of the milling cone remains unchanged after the last point of the milling cone leaves the whipstock.

3. The method for calculating the shape of the casing window opening according to claim 2, characterized in that: In step S2, the inner circle equation of the casing is: The projection equation of the milling cone bottom circle is: Solving the above two equations, we get Where: a is the distance between the center of the milling cone and the center of the casing O.

4. The method for calculating the shape of the casing window opening according to claim 3, characterized in that: In step 3, the intersection points of the maximum diameter of the milling cone and the inner wall of the casing are set to be E and F respectively, then The coordinates of point E are The coordinates of point F are Then the distance between two points FE is The distance between the two points FE is the maximum width of the window.

5. The method for calculating the shape of the casing window opening according to claim 4, characterized in that: In step 3, when the milling cone is milled from the inner wall of the casing to the outer wall of the casing, the lateral displacement of the milling cone is the displacement Δa of the center line of the milling cone from the initial state to the center line of the casing. Δa is divided into n equal parts, and the size of each equal part is Δy=Δa / n. Corresponding to each equal part, the window width corresponding to the ground casing is a=a0+iΔy, i=0~n; then the window width corresponding to each equal part is Then the analytical expression of W with respect to x is 6. The method for calculating the shape of the casing window opening according to claim 5, characterized in that: In step 3, the original distance between the center of the casing and the center of the window milling cone is a0=(Dd) / 2, but

Images