A method for calculating the inclination angle of a horizontal well entry window and application thereof

Abstract

The application provides a horizontal well entry window inclination calculation method, establishes an iterative calculation method of a range of well inclination angles required for uncovering a reservoir roof by determining principles of key parameters such as a landing position in an entry window stage and a full angle change rate, and forms an entry window stage well inclination calculation process and method. The method can provide a trajectory optimization basis in a horizontal well construction process, clearly define a range of well inclination angles required before the entry window, guide the drilling construction, reduce the construction risk, and provide technical support for the horizontal well entry window construction.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration technology, and in particular to a method for calculating the well inclination angle of a horizontal well entry window and its application. Background Technology

[0002] Horizontal well drilling typically targets relatively thin geological bodies; channel sand bodies are generally less than 20.00m thick, and shale gas well target windows are often only 4.00–6.00m, exceeding the resolution limit of seismic data and only providing macroscopic directional guidance. During the horizontal well window entry and landing phase, the designed trajectory is planned according to the predicted reservoir depth. However, in actual drilling, situations such as the target layer's vertical depth being advanced or delayed are common, easily leading to a significant extension of the drilling section or complex trajectories, significantly increasing the difficulty of later drilling operations, and even causing window entry failure, which is detrimental to speed and efficiency. Due to the uncertainty of reservoir depth, reasonably determining the well inclination required to uncover the reservoir top is crucial for successful window entry. Different formation dip angles also have a significant impact on window entry, and there is no mature method to determine the well inclination angle required to uncover the reservoir top, posing a significant risk to engineering operations.

[0003] To ensure successful horizontal well construction, the key is how to drill to the target point according to a given spatial location, facilitating drilling operations. This has led to the development of a soft-landing trajectory control method, dividing the well trajectory into "straight line segment - curved line segment - curved line segment - straight line segment." Based on this, the window entry stage is divided into two phases: reservoir top boundary exploration and target engagement. Trajectory optimization methods for reservoir top boundary exploration when the reservoir is explored earlier or later are studied to ensure the shortest target-front distance upon entry. Due to the limited accuracy of seismic interpretation and the difficulty in predicting reservoir depth, discrepancies between the actual and predicted reservoir top boundary depths are common during actual drilling. When geological targets are uncertain, trajectory optimization lacks a basis.

[0004] By applying logging-while-drilling technology to identify marker layers and determine formation dip angles, the well approached the target geological body layer by layer. By predicting the target layer's top depth, reasonable entry and landing points were determined. Based on the total angle variation rate, formation dip angle, and reservoir thickness, a formula for calculating the entry well inclination angle from the reservoir top to the landing position was established using trigonometric functions. The distance between the target point and the reservoir top was considered an approximate straight line. However, in actual drilling, the distance from the reservoir top to the target point involves a continuous increase in inclination, resulting in an approximately smooth curve. The constantly changing well inclination angle during this process affects subsequent parameter calculations, and using an approximate straight line leads to significant errors in the calculations.

[0005] Therefore, due to the prediction errors of underground geological bodies, there are certain uncertainties in reservoir depth, thickness, and formation dip angle. Furthermore, landing location, total angle change rate, and well inclination angle have a significant impact on the entry window effect. Thus, how to optimize the well inclination angle is one of the current challenges; a new calculation method that is suitable for practical applications is urgently needed. Summary of the Invention

[0006] In view of the uncertainty of underground geological conditions and the above-mentioned problems in the existing technology, this invention proposes a method for calculating the inclination angle of a horizontal well entry window and its application.

[0007] In a first aspect, the present invention proposes a method for calculating the inclination angle of a horizontal well entry window, comprising the following steps:

[0008] Step 1: Based on the drilling geological design and / or analysis of seismic data, obtain the burial depth H0′ of the top and bottom of the reservoir, the reservoir thickness H′, and the formation dip angle γ′ of the horizontal well to be drilled;

[0009] Step 2: Based on actual drilling data from the same mining area, correct the data from Step 1 to obtain the reservoir depth H0, thickness H, and formation dip angle γ;

[0010] Step 3: Determine the depth range of the target landing site based on the reservoir development;

[0011] Step 4: Determine the target well inclination angle Inc based on seismic data and multi-well comparison to predict formation dip angle;

[0012] Step 5: Determine the required full angle change rate K for the window entry stage based on the maximum full angle change rate of the directional tool used in the well and the maximum allowable full angle change rate for subsequent well completion operations;

[0013] Step 6: Set the step size of the loop calculation. Based on the reservoir burial depth H0, thickness H, formation dip angle γ, depth range, target well inclination angle Inc and total angle change rate K, adopt the loop iteration calculation method, apply the directional well trajectory calculation formula, and back-calculate the maximum well inclination angle Inc1 and minimum well inclination angle Inc2 required to uncover the top of the reservoir.

[0014] Step 7: Based on the maximum well inclination angle Inc1 and the minimum well inclination angle Inc2, determine the well inclination angle range Inc2~Inc1 required for the horizontal well to open the reservoir top.

[0015] As a specific embodiment of the present invention, in step 1, the predicted burial depth of the top and bottom of the reservoir of the horizontal well to be drilled is obtained by techniques including conventional seismic profiles and wave impedance inversion.

[0016] As a specific embodiment of the present invention, in step 2, the reservoir depth H0, thickness H and formation dip angle γ are obtained by a method including the following steps: comparing actual drilling data with drilling geological design and / or analytical seismic data, correcting the time-depth relationship of the seismic data according to the actual drilling data, converting the depth domain seismic profile, correcting the reservoir top and bottom depth H0′, reservoir thickness H′ and formation dip angle γ′ of the horizontal well to be drilled, and obtaining the reservoir depth H0, thickness H and formation dip angle γ.

[0017] It should be noted that, based on actual drilling data and compared with pre-drilling predictions, important geological boundaries and special lithologies are used as vertical characteristic marker layers. For each marker layer reached, the time-depth relationship of the seismic data is corrected based on the actual drilling data, the depth-domain seismic profile is reconstructed, and geological parameters such as reservoir depth, thickness, and dip angle are read again. Through this "layer-by-layer approximation" method using multiple marker layers, the error between the predicted and actual drilling data is continuously corrected, ultimately yielding the corrected reservoir depth H0, thickness H, and dip angle γ that most closely approximate the actual values.

[0018] In a specific embodiment of the present invention, in step 3, the depth range of the target landing position includes the upper limit H of the landing. a1 and landing lower limit H a2 ;

[0019] The upper limit of landing is set at reservoir α1, and the vertical depth of the upper limit of landing is set to H. a1 The calculation formula is:

[0020] H a1 =H0+α1×H

[0021] Among them, H a1 The upper limit of the vertical landing depth (m);

[0022] α1 is a positive number less than 1.

[0023] H represents the corrected true vertical thickness of the reservoir (m).

[0024] The lower landing limit is set at reservoir α2, and the vertical depth of the lower landing limit is set to H. a2 The calculation formula is:

[0025] H a2 =H0 + α2×H

[0026] Among them, H a2 Lower limit of landing vertical depth (m)

[0027] H is the corrected true vertical thickness of the reservoir (m);

[0028] α2 is a positive number that is not less than α1 and not greater than 1.

[0029] Due to uncertainties in geological conditions, the landing location is limited to a specific depth range to ensure successful target acquisition; the upper limit of the landing is set at reservoir α1, and the vertical depth of the upper limit of the landing is defined as H. a1 The calculation formula is:

[0030] H a1 =H0+α1×H

[0031] The lower landing limit is set at reservoir α2, and the vertical depth of the lower landing limit is set to H. a2The calculation formula is:

[0032] H a2 =H0 + α2×H

[0033] Where α1 is a positive number less than 1, and a value of 1 / 3 is recommended;

[0034] α2 is a positive number that is not less than α1 and not greater than 1, and a value of 2 / 3 is recommended.

[0035] In a specific embodiment of the present invention, in step 4, the target well inclination angle Inc is determined based on seismic data and the formation dip angle γ of multi-well correlation, with Inc as the target well inclination angle.

[0036] Inc=(90-γ)

[0037] Where Inc is the inclination angle of the target well, in degrees;

[0038] γ is the dip angle of the formation (downdip is positive, updip is negative), in degrees.

[0039] In a specific embodiment of the present invention, in step 5, the required total angle change rate K for the window entry stage is determined based on the maximum total angle change rate of the directional tool used in the well and the maximum total angle change rate allowed for subsequent well completion operations, and the maximum total angle change rate K of the directional tool is selected. 工具 The maximum allowable full-angle change rate K for subsequent well completion operations 完井 The minimum value, multiplied by an additional coefficient β, is...

[0040] When K 工具 >K 完井 When, K = K 完井 ×β

[0041] When K 工具 ≤K 完井 When, K = K 工具 ×β

[0042] Where K is the maximum allowable total angle variation rate (° / 100m) during horizontal well construction.

[0043] K 工具 The maximum total angle change rate (° / 100m) of the orientation tool.

[0044] K 完井 The maximum allowable full-angle change rate (° / 100m) for well completion operations.

[0045] β is an additional coefficient, a positive number not greater than 1.

[0046] It should be noted that the maximum total angle change rate of the directional tool is determined by the performance of the tool itself; the maximum allowable total angle change rate for well completion is an empirical value of the work area, which needs to be followed during construction and is not a fixed value. In the method of this invention, the value of an additional coefficient is added.

[0047] As a specific embodiment of the present invention, in step 6, the calculation method using iterative loops independently employs any one of the following: angular average method, corrected angular average method, and radius of curvature method; to obtain the maximum wellbore inclination angle as In. c1 The minimum well inclination angle is In c2 .

[0048] In a specific embodiment of the present invention, step 6 involves setting the step size Δi for the iterative calculation. A value of 0.1–1° is recommended. A smaller Δi results in higher calculation accuracy but also a larger computational load. An iterative calculation method is used, employing any one of the directional well trajectory calculation formulas, such as the angular mean method, the corrected angular mean method, or the radius of curvature method, to back-calculate the maximum well inclination angle required to uncover the reservoir top. The calculation process is demonstrated using the angular mean method:

[0049] Calculate the previous wellbore inclination angle based on the step size: Inc1 = Inc - Δi

[0050] Calculate the average of the two well inclination angles: Inc_v1 = (Inc + Inc1) / 2

[0051] The length of the well section (depth) required to increase the well inclination angle from Inc1 to Inc is calculated as follows: ΔL1 = 100 × Δi / K

[0052] The required vertical thickness to increase the well inclination angle from Inc1 to Inc is calculated as follows: ΔH1 = ΔL1 × cos(Inc_v1)

[0053] Calculate the vertical depth when the well inclination angle is Inc1: H1 = H a1 -ΔH1

[0054] Compare the relationship between H0 and H1. If H1 ≤ H0, stop the calculation; Inc1 is the maximum well inclination required to uncover the reservoir top. If H1 > H0, let Inc = Inc1. a1 =H1, return to the previous step and calculate again until H1≤H0.

[0055] As a specific embodiment of the present invention, similarly, the step size Δi of the cyclic calculation is set, and a value of 0.1 to 1° is recommended. The smaller Δi is, the higher the calculation accuracy, but the greater the computational load. A cyclic iterative calculation method is adopted, and any one of the directional well trajectory calculation formulas, such as the angular mean method, the corrected angular mean method, and the radius of curvature method, is applied to back-calculate the minimum well inclination angle required to uncover the reservoir top. The calculation process is demonstrated using the angular mean method:

[0056] Calculate the previous wellbore inclination angle based on the step size: Inc2 = Inc - Δi

[0057] Calculate the average of the two well inclination angles: Inc_v2 = (Inc + Inc2) / 2

[0058] The length of the well section (depth) required to increase the well inclination angle from Inc2 to Inc is calculated as follows: ΔL2 = 100 × Δi / K

[0059] The required vertical thickness for increasing the well inclination angle from Inc2 to Inc is calculated as follows: ΔH2 = ΔL2 × cos(Inc_v2)

[0060] Calculate the vertical depth when the well inclination angle is Inc2: H2 = H a2 -ΔH2

[0061] Compare the relationship between H0 and H2. If H2 ≤ H0, stop the calculation; Inc2 is the minimum well inclination required to uncover the reservoir top. If H2 > H0, let Inc = Inc2. a2 =H2, return to the previous step and calculate again until H2≤H0.

[0062] As a specific embodiment of the present invention, in step 7, the range of well inclination angles In required to uncover the reservoir top is determined. c2 ~In c1 .

[0063] As a specific embodiment of the present invention, during construction, the inclination angle of the horizontal well entering the window is controlled between the maximum and minimum inclination angles, that is, the minimum inclination angle cannot be lower than Inc2 and the maximum inclination angle cannot be greater than Inc1, so as to accurately enter the window and hit the target.

[0064] Secondly, the present invention provides the application of the well inclination angle calculation method for the horizontal well entry window in the fields of exploration orientation and geological guidance.

[0065] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0066] 1. The calculation method of the present invention has high calculation accuracy: the calculation step size can be set as needed, and the well trajectory from the target point to the top of the reservoir is decomposed into extremely small well segments according to the calculation step size. Each well segment is calculated separately, avoiding the calculation error caused by simplifying the trajectory to a straight line. The calculation process takes into account the influence of the continuous change of the well inclination angle. The cyclic iterative calculation method adopted improves the accuracy of the calculation and provides a reliable basis for trajectory optimization.

[0067] 2. The calculation method of this invention reduces the difficulty of trajectory optimization: it provides a selection range of well inclination angles required when uncovering the reservoir top. By calculating the required maximum and minimum well inclination angles, the appropriate angle can be selected based on the actual construction conditions, and the well inclination can be controlled within this range. Even if the underground geological conditions change drastically, there is still considerable room for adjustment, making trajectory optimization easier and effectively ensuring the success rate of hitting the target in horizontal wells.

[0068] 3. The calculation method of the present invention is convenient to use: the required calculation formula is not complicated, and the result can be obtained quickly by using computer programming or Excel spreadsheet. Attached Figure Description

[0069] Figure 1 This is a schematic diagram of the method for calculating the inclination angle of a horizontal well entry window according to the present invention. Detailed Implementation

[0070] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0071] Example 1

[0072] This embodiment provides a method for calculating the inclination angle of a horizontal well entrance, applied to well D15 in area D. Specific details are as follows:

[0073] Step 1: Drilling geological design predicts that the top and bottom depths of the reservoir in the horizontal well to be drilled are 2614 meters, the vertical depth is 2320 meters, the true vertical thickness of the reservoir is 6 meters, and the formation dip angle is -8°.

[0074] Step 2: Based on the actual drilling data and compared with the pre-drilling prediction, the formation will be significantly pushed back. The corrected reservoir depth is 2783 meters, vertical depth is 2536 meters, vertical thickness is 6 meters, and formation dip angle is -8°.

[0075] Step 3: Based on the reservoir development, determine the landing location to be 1.98–4.02 meters within the reservoir.

[0076] Step 4: Based on the reservoir development, determine the target well inclination angle to be 98°;

[0077] Step 5: The maximum allowable total angle change rate for directional tools and well completion is 24 degrees / 100 meters. The additional coefficient is taken as 0.875. The required total angle change rate K for the window entry stage is determined to be 21 degrees / 100 meters.

[0078] Step 6: Set the step size of the iterative calculation to 0.1°;

[0079] Step 7: Back-calculate the well inclination angle required to uncover the reservoir top, which is 88.2–91°.

[0080] During construction, the maximum and minimum well inclination angles calculated in Example 1 were used to control the well inclination angle within this range. Due to the significant delay in formation depth, the well began to stabilize at a depth of 2760 meters and continued drilling at a steady 90° angle until a depth of 2820 meters and a vertical depth of 2543 meters was reached to expose the top of the reservoir. The well landed at a position 2.6 meters inside the reservoir, ensuring accurate entry of the horizontal well.

[0081] Table 1. Parameters for Iterative Calculation of Inclination Angle of Well D15

[0082]

[0083]

[0084] Example 2

[0085] This embodiment provides a method for calculating the inclination angle of a horizontal well entrance, applied to well W6 in work area W. Specific details are as follows:

[0086] Step 1: Drilling geological design predicts that the top and bottom depths of the reservoir in the horizontal well to be drilled are 2791 meters, the vertical depth is 2460 meters, the true vertical thickness of the reservoir is 5 meters, and the formation dip angle is 6°.

[0087] Step 2: Based on the actual drilling data and compared with the pre-drilling prediction, the formation was slightly pushed back. The corrected reservoir depth is 2820 meters, vertical depth is 2490 meters, vertical thickness is 5 meters, and formation dip angle is 8°.

[0088] Step 3: Based on the reservoir development, determine the landing location to be 1.65–3.35 meters within the reservoir;

[0089] Step 4: Determine the target well inclination angle to be 82° based on the formation dip angle;

[0090] Step 5: The maximum allowable total angle change rate for the directional tool and well completion is 18 degrees / 100 meters, with an additional coefficient of 0.89. The required total angle change rate K for the window entry stage is determined to be 16 degrees / 100 meters.

[0091] Step 6: Set the step size of the iterative calculation to 0.1°;

[0092] Step 7: Back-calculate the well inclination angle required to uncover the reservoir top, which is 74.1–76.4°.

[0093] During the construction process, the maximum and minimum well inclination angles calculated in Example 2 were used to control the well inclination angle within this range. Starting from a well depth of 2800 meters, the well was steadily drilled at a 75° angle until a well depth of 2840 meters and a vertical depth of 2498 meters was reached to expose the top of the reservoir. The well landed at a position of 2.4 meters inside the reservoir, ensuring accurate entry into the reservoir.

[0094] Table 2. Parameters for Iterative Calculation of Inclination Angle of Well W6 (Entrance Window)

[0095] project numerical values unit illustrate Well inclination calculation step length 0.1 ° Step size of iterative calculation Stratum dip angle 8 ° Downward tilt is positive, upward tilt is negative. Target well inclination 82 ° Window full-angle change rate 16 ° / 100m reservoir thickness 5 m Landing at the highest point of the reservoir 1 / 3 Recommended value: 1 / 3 Landing at the lowest point of the reservoir 2 / 3 Recommended value: 2 / 3 Theoretical target point minimum vertical depth from the top 1.65 m Theoretical target point maximum vertical depth from the top 3.35 m Maximum well inclination required to uncover the reservoir top 76.4 ° Minimum well inclination required to uncover the reservoir top 74.1 °

[0096] Comparative Example

[0097] This comparative example provides a prior art method for calculating the inclination angle of a horizontal well entry window. This method is applied to the project in Example 2, and the specific details are as follows:

[0098] Conventional methods cannot provide a predicted range for well inclination angle. Based on the predicted reservoir location, the well inclination will reach 78° at a depth of 2820 meters and a vertical depth of 2490 meters. However, this depth is still more than 8 meters below the reservoir location. In addition, the formation dip angle is 6 degrees downdip, so the reservoir top can only be exposed at a depth of about 2870 meters. The error is about 30 meters compared with the example.

[0099] In summary, the well inclination angle calculation method of this invention clarifies the principles for determining key parameters such as the landing position and the rate of change of the total angle during the window entry stage, establishes an iterative calculation method for the range of well inclination angles required to uncover the reservoir top, and forms a well inclination angle calculation process and method for the window entry stage. It can provide trajectory optimization basis during horizontal well construction, clarify the range of well inclination angles required before window entry, guide drilling operations, reduce construction risks, and provide technical support for horizontal well window entry operations.

[0100] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0101] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for calculating the inclination angle of a horizontal well entrance, characterized in that, Includes the following steps: Step 1: Based on the drilling geological design and / or analysis of seismic data, obtain the burial depth H0′ of the top and bottom of the reservoir, the reservoir thickness H′, and the formation dip angle γ′ of the horizontal well to be drilled; Step 2: Based on actual drilling data from the same mining area, correct the data from Step 1 to obtain the reservoir depth H0, thickness H, and formation dip angle γ; Step 3: Determine the depth range of the target landing site based on the reservoir development; Step 4: Determine the target well inclination angle Inc based on seismic data and multi-well comparison to predict formation dip angle; Step 5: Determine the required full angle change rate K for the window entry stage based on the maximum full angle change rate of the directional tool used in the horizontal well to be drilled and the maximum full angle change rate allowed for subsequent well completion operations; Step 6: Set the step size of the loop calculation. Based on the reservoir burial depth H0, thickness H, formation dip angle γ, depth range, target well inclination angle Inc and total angle change rate K, adopt the loop iteration calculation method, apply the directional well trajectory calculation formula, and back-calculate the maximum well inclination angle Inc1 and minimum well inclination angle Inc2 required to uncover the top of the reservoir. Step 7: Based on the maximum well inclination angle Inc1 and the minimum well inclination angle Inc2, determine the range of well inclination angles Inc2 to Inc1 required for the horizontal well to open the reservoir top.

2. The calculation method according to claim 1, characterized in that, In step 1, the predicted depth of the top and bottom of the reservoir in the horizontal well to be drilled is obtained by techniques including conventional seismic profiling and / or wave impedance inversion.

3. The calculation method according to claim 1 or 2, characterized in that, In step 2, the reservoir depth H0, thickness H, and formation dip angle γ are obtained by a method including the following steps: comparing actual drilling data with drilling geological design and / or analytical seismic data, correcting the time-depth relationship of the seismic data based on the actual drilling data, converting the depth domain seismic profile, and correcting the reservoir top and bottom depth H0′, reservoir thickness H′, and formation dip angle γ′ of the horizontal well to be drilled, thereby obtaining the reservoir depth H0, thickness H, and formation dip angle γ.

4. The calculation method according to claim 1 or 2, characterized in that, In step 3, the depth range of the target landing position includes the upper limit of the landing depth. and landing lower limit ; The upper limit of landing is set at reservoir α1, and the vertical depth of the upper limit of landing is set to H. a1 , H a1 =H0+α1×H in, The upper limit of the landing vertical depth (m); α1 is a positive number less than 1; H is the corrected true vertical thickness of the reservoir (m). The lower landing limit is set at reservoir α2, and the vertical depth of the lower landing limit is set to H. a2 , H a2 =H0+α2×H in, The lower limit of the vertical depth for landing (m); H is the true vertical thickness of the reservoir (m). α2 is a positive number that is not less than α1 and not greater than 1.

5. The calculation method according to claim 1 or 2, characterized in that, In step 4, the target well inclination angle Inc is determined based on seismic data and the formation dip angle γ of multi-well correlation. Let Inc be the target well inclination angle. Inc=(90-γ) Where Inc is the inclination angle of the target well, in degrees; γ is the dip angle of the formation, with downdip being a positive number and updip being a negative number, in degrees.

6. The calculation method according to claim 1 or 2, characterized in that, In step 5, the required total angle change rate K for the window entry stage is determined based on the maximum total angle change rate of the directional tool used in the horizontal well to be drilled and the maximum total angle change rate allowed for subsequent well completion operations, and the maximum total angle change rate K of the directional tool is selected. 工具 The maximum allowable full-angle change rate K for subsequent well completion operations 完井 The minimum value, multiplied by an additional coefficient β, is... When K 工具 >K 完井 When, K = K 完井 ×β When K 工具 ≤K 完井 When, K = K 工具 ×β Where K is the maximum allowable full angle change rate (° / 100m) during horizontal well construction. K 工具 The maximum total angle change rate (° / 100m) of the orientation tool. K 完井 The maximum allowable full-angle change rate (° / 100m) for well completion operations. β is an additional coefficient, a positive number not greater than 1.

7. The calculation method according to claim 1 or 2, characterized in that, In step 6, the calculation method using iterative loops independently employs any one of the following: angular mean method, corrected angular mean method, or radius of curvature method; to obtain the maximum wellbore inclination angle In. c1 The minimum well inclination angle is In c2 .

8. The calculation method according to any one of claims 1-7, characterized in that, The method for calculating the inclination angle of the horizontal well entry window is applied in the fields of exploration orientation and geological steering.

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