Method for determining the maximum horizontal stress in the state of a horizontal well

Abstract

The application discloses a method for determining the horizontal maximum stress in the horizontal well state, and relates to the oil drilling and well completion technical field, and comprises the following steps: a) judging whether the radial induced fracture exists on the well wall of the horizontal well; b) respectively calculating the components of the vertical, horizontal maximum and horizontal minimum stress on the well wall of the horizontal well; c) calculating the radial, circumferential and axial normal stress components on the well wall in the horizontal well state, and calculating the minimum value of the circumferential normal stress component and the axial normal stress component; d) drawing the stress polygon of the target formation and the upper limit and lower limit constraint lines of the horizontal maximum stress; and e) determining the upper limit and lower limit of the horizontal maximum stress according to the intersection points of the horizontal minimum stress and the upper limit and lower limit constraint lines of the horizontal maximum stress. The horizontal maximum stress in the horizontal well state can be quickly and accurately determined by the application, and the technical problem that the horizontal maximum stress cannot be accurately determined in the horizontal well state in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of oil drilling and completion technology, and specifically to a method for determining the maximum horizontal geostress in a horizontal well. Background Technology

[0002] Accurately obtaining in-situ stress is of great significance for oil and gas exploration and development, and is also an important basic parameter required for wellbore stability analysis and fracturing optimization design. Vertical in-situ stress can be obtained by integrating the volumetric density of well logging, and the minimum horizontal in-situ stress can be determined by methods such as small-scale fracturing and ground failure tests. However, the maximum horizontal in-situ stress cannot be obtained directly and is the most difficult component to determine in in-situ stress modeling.

[0003] In existing technologies, Zoback et al. proposed a stress polygon model and combined it with imaging logging of wellbore collapse and axially induced fractures to constrain the range of maximum horizontal in-situ stress in vertical wells. However, this method mainly utilizes axially induced fractures in vertical wells, while wellbore collapse and induced fractures are rarely found simultaneously in formations at the same depth. This makes it difficult to simultaneously constrain the upper and lower limits of the maximum horizontal in-situ stress. Furthermore, in the stress polygon model proposed by Zoback et al., the fault friction coefficient is typically taken as 0.6–0.8, which does not consider the influence of formation variations, leading to errors in in-situ stress prediction and affecting the accuracy of the prediction.

[0004] Therefore, there is an urgent need for a method that can quickly and accurately determine the range of maximum horizontal stress in a horizontal well, and is also applicable to determining the maximum horizontal stress in different strata and lithologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for determining the maximum horizontal in-situ stress under horizontal well conditions. This invention can quickly and accurately determine the maximum horizontal in-situ stress under horizontal well conditions, and is also applicable to the determination of the maximum horizontal in-situ stress for different strata lithologies. It solves the technical problem that the prior art cannot accurately determine the maximum horizontal in-situ stress under horizontal well conditions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for determining the maximum horizontal in-situ stress under horizontal well conditions includes the following steps:

[0008] (a) Collect imaging logging data of the target formation, and determine whether there are radially induced fractures on the wellbore of the horizontal well based on the imaging logging data. If there are radially induced fractures, proceed to step (b).

[0009] (b) Calculate the vertical ground stress σ respectively. V Horizontal maximum ground stress σH and the minimum horizontal ground stress σ h The component σ on the horizontal wellbore x σ y σ z ;

[0010] (c) Calculate the radial normal stress component σ on the wellbore wall under the horizontal well condition based on the wellbore direction and the results of step (b). rr Circumferential normal stress component σ θθ and axial normal stress component σ zz And calculate the circumferential normal stress component σ θθ The minimum value σ θθmin and axial normal stress component σ zz The minimum value σ zzmin ;

[0011] (d) Draw a stress polygon of the target formation based on the stress of the target formation. Within the range of the drawn stress polygon, draw the upper and lower limit constraint lines of the maximum horizontal stress based on the radially induced fracture based on the results of step (c).

[0012] (e) Based on the minimum horizontal ground stress σ h Respectively compared with the maximum horizontal ground stress σ H The intersection of the upper and lower limit constraint lines determines the upper and lower limits of the maximum horizontal ground stress.

[0013] The stress polygon of the target formation is defined by the minimum horizontal stress σ. h and vertical ground stress σ V The ratio σ h / σ V The horizontal axis is σ, and the maximum horizontal ground stress is σ. H and vertical ground stress σ V The ratio σ H / σ V It is plotted in a coordinate system with the vertical axis as the coordinate.

[0014] The specific process for determining the upper and lower limits of the maximum horizontal ground stress is as follows: first, by using the minimum horizontal ground stress σ... h With vertical ground stress σ V The ratio σ h / σ V Find the intersection point with the upper and lower limit constraint lines of the maximum horizontal ground stress, and locate the maximum horizontal ground stress σ on the vertical axis. H With vertical ground stress σ V The range of the ratio σ H / σ V Then the vertical ground stress σ V Substitute into the determined ratio range σ H / σV This gives the upper and lower limits of the maximum horizontal ground stress.

[0015] In step (b), the vertical ground stress σ V Horizontal maximum ground stress σ H and the minimum horizontal ground stress σ h The component σ on the horizontal wellbore x σ y σ z The calculation method is as follows:

[0016]

[0017] In equation (1), β b The azimuth angle is the well inclination angle, in degrees.

[0018] In step (c), the radial normal stress component σ on the horizontal wellbore wall rr Circumferential normal stress component σ θθ and axial normal stress component σ zz The calculation method is as follows:

[0019]

[0020] In equation (2), θ is the well perimeter angle, in degrees; P p P is the formation pore pressure, measured in MPa. w ν is the pressure of the fluid column in the well, in MPa; α is the effective stress coefficient, dimensionless; ν is Poisson's ratio, dimensionless; E is Young's modulus, in GPa; α m It is the coefficient of thermal expansion of the geological strata, in °C. -1 T0 is the initial formation temperature, in °C; T w It is the bottom-hole circulation temperature of the drilling fluid, in °C.

[0021] In step (c), the minimum value σ θθmin Through the circumferential normal stress component σ θθ The minimum value σ is obtained when θ = 0°. zzmin Through the axial normal stress component σ zz The minimum value σ is obtained when θ = 0°. θθmin and minimum value σ zzmin The calculation method is as follows:

[0022]

[0023] In equation (3), σ θθmin and σ zzmin σ is the circumferential normal stress component under horizontal well conditions. θθ and axial normal stress component σ zz The minimum value at θ = 0°, in MPa.

[0024] In step (d), the stress polygon of the target formation is drawn using the following formula:

[0025]

[0026] In equation (4), α is the effective stress coefficient, which is dimensionless; P p It represents the formation pore pressure, in MPa; μf represents the fault friction coefficient, which is dimensionless.

[0027] The method for calculating the fault friction coefficient is as follows:

[0028]

[0029] In equation (5), ν is Poisson's ratio, which is dimensionless.

[0030] In step (d), the circumferential normal stress component σ θθ The minimum value σ θθmin and axial normal stress component σ zz The minimum value σ zzmin Under the premise of satisfying the constraints, according to the radial normal stress component σ rr Circumferential normal stress component σ θθ and axial normal stress component σ zz Draw the upper and lower limit constraint lines for the maximum horizontal geostress based on radially induced fractures.

[0031] In step (d), the upper and lower limit constraint lines of the maximum horizontal in-situ stress based on the radially induced crack are drawn using the following formula:

[0032]

[0033] In equation (6), the circumferential normal stress component σ θθ The minimum value σ θθmin n and axial normal stress component σ zz The minimum value σ zzmin The constraint condition that is satisfied is σ zzmin ≤-σ t and σ zzmin ≤σ θθmin .

[0034] In step (a), the basis for determining whether there are radially induced fractures on the wellbore of a horizontal well is the presence of a set of approximately parallel and discontinuous dark short straight lines on the imaging logging data.

[0035] In step (b), the vertical ground stress σ V The minimum horizontal geostress σ can be calculated through density logging integration. h It can be obtained through hydraulic fracturing or formation leakage tests.

[0036] The advantages of using this invention are:

[0037] 1. The method for determining the maximum horizontal stress in a horizontal well as described in this invention mainly includes five steps. The advantage of step (a) is that it is convenient to obtain the radial induced fractures of the horizontal well intuitively and easily through imaging logging data; the advantage of step (b) is that it can obtain the component of the stress on the well wall in the horizontal well state; the advantage of step (c) is that it can determine the constraint conditions for the maximum horizontal stress; the advantage of step (d) is that it can conveniently determine the limiting range of the maximum horizontal stress; and the advantage of step (e) is that it can quickly and accurately determine the maximum horizontal stress in the horizontal well state by combining the aforementioned results.

[0038] In summary, this invention only requires the use of radially induced fractures in a horizontal well to establish a stress polygon and upper and lower limit constraint lines for the maximum horizontal stress. Combined with the minimum horizontal stress, the range of the maximum horizontal stress in a horizontal well can be quickly, accurately, and conveniently determined. The process is not only simple and highly accurate, but also applicable to determining the maximum horizontal stress for different lithologies.

[0039] 2. In practical applications, this invention can quickly define the range of maximum horizontal stress without the need for a complex geostress calculation model. Attached Figure Description

[0040] Figure 1 This is a flowchart of the present invention;

[0041] Figure 2 This is an example diagram showing the identification of radial induced fractures in a horizontal well based on imaging logging data.

[0042] Figure 3 A schematic diagram for determining the upper and lower limits of the maximum horizontal geostress for a certain horizontal well. Detailed Implementation

[0043] Example 1

[0044] This invention provides a method for determining the maximum horizontal in-situ stress under horizontal well conditions, such as... Figure 1 As shown, it includes the following steps:

[0045] (a) Collect imaging logging data of the target formation and determine whether there are radially induced fractures on the wellbore of the horizontal well based on the imaging logging data. If there are radially induced fractures, proceed to step (b); if there are no radially induced fractures, this method cannot be used to determine the maximum horizontal stress in the horizontal well state.

[0046] The basis for determining whether radial induced fractures exist on the wellbore of a horizontal well is that there is a set of approximately parallel and discontinuous dark short lines on the imaging logging data. If there is a set of approximately parallel and discontinuous dark short lines, it indicates that radial induced fractures exist; otherwise, there are no radial induced fractures.

[0047] (b) Collect target formation physical properties and rock mechanics parameters. These target formation physical properties and rock mechanics parameters can be obtained through the interpretation of conventional sonic logging data and empirical relationships of dynamic and static conversion, or through laboratory rock mechanics parameter testing. The collected target formation physical properties and rock mechanics parameters specifically include vertical geostress, horizontal minimum geostress, formation pore pressure, Young's modulus, Poisson's ratio, formation tensile strength, initial formation temperature, formation rock thermal expansion coefficient, in-well fluid column pressure, effective stress coefficient, and drilling fluid bottom hole circulation temperature.

[0048] Then, based on the collected target stratum physical properties and rock mechanical parameters, the vertical stress σ is calculated respectively. V Horizontal maximum ground stress σ H and the minimum horizontal ground stress σ h The component σ on the horizontal wellbore x σ y σ z .

[0049] Specifically, the vertical ground stress σ V Horizontal maximum ground stress σ H and the minimum horizontal ground stress σ h The component σ on the horizontal wellbore x σ y σ z The calculation method is as follows:

[0050]

[0051] In equation (1), β b The azimuth angle is the well inclination angle, in degrees.

[0052] It should be noted that the aforementioned vertical ground stress σ V The minimum horizontal geostress σ can be calculated through density logging integration. h It can be obtained through hydraulic fracturing or formation leakage tests.

[0053] (c) Determine the horizontal wellbore direction through drilling design or actual drilling, and based on the horizontal wellbore direction and the vertical in-situ stress σ obtained in step (b). V Maximum horizontal ground stress σ H and the minimum horizontal ground stress σ h The component σ on the horizontal wellbore x σ y σz Calculate the radial normal stress component σ on the wellbore wall under horizontal well conditions. rr Circumferential normal stress component σ θθ and axial normal stress component σ zz And calculate the circumferential normal stress component σ. θθ The minimum value σ θθmin and axial normal stress component σ zz The minimum value σ zzmin .

[0054] Specifically, the radial normal stress component σ on the wellbore wall of a horizontal well rr Circumferential normal stress component σ θθ and axial normal stress component σ zz The calculation method is as follows:

[0055]

[0056] In equation (2), θ is the well perimeter angle, in degrees; P p P is the formation pore pressure, measured in MPa. w ν is the pressure of the fluid column in the well, in MPa; α is the effective stress coefficient, dimensionless; ν is Poisson's ratio, dimensionless; E is Young's modulus, in GPa; α m It is the coefficient of thermal expansion of the geological strata, in °C. -1 T0 is the initial formation temperature, in °C; T w It is the bottom-hole circulation temperature of the drilling fluid, in °C.

[0057] Furthermore, the circumferential normal stress component σ θθ The minimum value σ θθmin Through the circumferential normal stress component σ θθ The axial normal stress component σ is obtained at θ = 0°. zz The minimum value σ zzmin Through the axial normal stress component σ zz Obtained at θ = 0°. Circumferential normal stress component σ θθ The minimum value σ θθmin and axial normal stress component σ zz The minimum value σ zzmin The calculation method is as follows:

[0058]

[0059] In equation (3), σ θθmin and σ zzmin σ is the circumferential normal stress component under horizontal well conditions. θθ and axial normal stress component σ zz The minimum value at θ = 0°, in MPa.

[0060] (d) Draw a stress polygon of the target stratum based on the target stratum stress. The stress polygon of the target stratum is based on the minimum horizontal stress σ. h and vertical ground stress σ V The ratio σ h / σ V The horizontal axis is σ, and the maximum horizontal ground stress is σ. H and vertical ground stress σ V The ratio σ H / σ V The stress polygon, plotted in a coordinate system with the vertical axis as the coordinate system, serves to define the entire range of geostress.

[0061] Within the drawn stress polygon, draw upper and lower limit constraint lines for the maximum horizontal geostress based on the results of step (c).

[0062] Specifically, in the circumferential normal stress component σ θθ The minimum value σ θθmin and axial normal stress component σ zz The minimum value σ zzmin Under the premise of satisfying the constraints, according to the radial normal stress component σ rr Circumferential normal stress component σ θθ and axial normal stress component σ zz Draw the upper and lower limit constraint lines for the maximum horizontal geostress based on radially induced fractures.

[0063] Furthermore, the stress polygon of the target stratum is drawn using the following formula:

[0064]

[0065] In equation (4), α is the effective stress coefficient, which is dimensionless; P p It represents the formation pore pressure, in MPa; μf represents the fault friction coefficient, which is dimensionless.

[0066] The method for calculating the fault friction coefficient is as follows:

[0067]

[0068] In equation (5), ν is Poisson's ratio, which is dimensionless.

[0069] Furthermore, the upper and lower limit constraint lines for the maximum horizontal in-situ stress based on radially induced cracks are derived using the following formulas:

[0070]

[0071] In equation (6), the circumferential normal stress component σ θθ The minimum value σ θθminn and axial normal stress component σ zz The minimum value σ zzmin The constraint condition that is satisfied is σ zzmin ≤-σ t and σ zzmin ≤σ θθmin .

[0072] (e) Based on the minimum horizontal ground stress σ h Respectively compared with the maximum horizontal ground stress σ H The intersection of the upper and lower limit constraint lines determines the upper and lower limits of the maximum horizontal ground stress.

[0073] Specifically, the process for determining the upper and lower limits of the maximum horizontal ground stress is as follows: first, use the minimum horizontal ground stress σ... h With vertical ground stress σ V The ratio σ h / σ V Find the intersection point with the upper and lower limit constraint lines of the maximum horizontal ground stress, and locate the maximum horizontal ground stress σ on the vertical axis. H With vertical ground stress σ V The range of the ratio σ H / σ V Then the vertical ground stress σ V Substitute into the determined ratio range σ H / σ V This gives the upper and lower limits of the maximum horizontal ground stress.

[0074] This invention employs the aforementioned specific process. In implementation, it only requires the use of radially induced fractures in a horizontal well to establish a stress polygon and upper and lower limit constraint lines for the maximum horizontal geostress. Combined with the minimum horizontal geostress, the range of the maximum horizontal geostress under horizontal well conditions can be quickly, accurately, and conveniently determined. Not only is the process simple and highly accurate, but it is also applicable to determining the maximum horizontal geostress for different lithologies.

[0075] Example 2

[0076] This embodiment provides a more detailed description of Embodiment 1 using a specific horizontal well as an example. The specific process is as follows.

[0077] (a) Collect imaging logging data of the target formation to determine whether radial induced fractures exist on the wellbore of the horizontal well.

[0078] Figure 2 This image shows an example of radially induced fractures in an imaging logging image of a horizontal well. The radially induced fractures are a set of approximately parallel and discontinuous dark short straight lines, outlined by a blue dashed box. In the image, T represents the height of the horizontal wellbore, S represents the sidewall of the horizontal wellbore, and B represents the bottom edge of the horizontal wellbore.

[0079] (b) Collect target formation physical properties and rock mechanics parameters. These parameters can be obtained through the interpretation of conventional sonic logging data and empirical relationships of dynamic-static conversion, or through laboratory rock mechanics parameter testing. The collected target formation physical properties and rock mechanics parameters specifically include vertical geostress, horizontal minimum geostress, formation pore pressure, Young's modulus, Poisson's ratio, formation tensile strength, initial formation temperature, formation rock thermal expansion coefficient, well fluid column pressure, effective stress coefficient, and drilling fluid bottom hole circulation temperature.

[0080] In this embodiment, the relevant parameters mentioned above are shown in the table below:

[0081]

[0082]

[0083] (c) First calculate the vertical stress σ based on the wellbore direction of the horizontal well. V Maximum horizontal ground stress σ H and the minimum horizontal ground stress σ h The component σ on the horizontal wellbore x σ y σ z Then, calculate the radial normal stress component σ on the well wall under the horizontal well condition. rr Circumferential normal stress component σ θθ and axial normal stress component σ zz And calculate the circumferential normal stress component σ θθ The minimum value σ θθmin and axial normal stress component σ zz The minimum value σ zzmin The specific calculation method is as follows:

[0084]

[0085] In equation (1), σ x σ y and σ z These are the components of vertical geostress, maximum horizontal geostress, and minimum horizontal geostress on the horizontal wellbore wall, respectively, in MPa; θ is the wellbore angle, in °; P p P is the formation pore pressure, measured in MPa. w ν is the pressure of the fluid column in the well, in MPa; α is the effective stress coefficient, dimensionless; ν is Poisson's ratio, dimensionless; E is Young's modulus, in GPa; α m It is the coefficient of thermal expansion of the geological strata, in °C. -1 T0 is the initial formation temperature, in °C; T w It is the bottom-hole circulation temperature of the drilling fluid, in °C.

[0086] Among them, the vertical ground stress σ V Horizontal maximum ground stress σ H and the minimum horizontal ground stress σ h The component σ on the horizontal wellbore x σ y σ z The specific calculation method is as follows:

[0087]

[0088] In equation (2), σ V σ H and σ h These are the vertical ground stress, the maximum horizontal ground stress, and the minimum horizontal ground stress, respectively, in MPa; β b β is the well inclination azimuth. b The azimuth angle is the well inclination angle, in degrees.

[0089] In this embodiment, the wellbore direction of the horizontal well is along the direction of minimum horizontal stress, where the direction of minimum horizontal stress is 0°, i.e., β in equation (2) b =0°, thus obtaining the component of the geostress on the horizontal wellbore wall σ x σ y and σ z :

[0090]

[0091] (d) Under the minimum horizontal ground stress σ h and vertical ground stress σ V The ratio σ h / σ V The horizontal axis is σ, and the maximum horizontal ground stress is σ. H and vertical ground stress σ V The ratio σ H / σ V To plot the stress polygon of the target formation in the coordinate system of the vertical axis, the stress polygon of the target formation is obtained by the following formula:

[0092]

[0093] In equation (4), α is the effective stress coefficient, which is dimensionless; P p It represents the formation pore pressure, in MPa; μf represents the fault friction coefficient, which is dimensionless.

[0094] The method for calculating the fault friction coefficient is as follows:

[0095]

[0096] In equation (5), ν is Poisson's ratio, which is dimensionless.

[0097] Furthermore, the upper and lower limit constraint lines for the maximum horizontal in-situ stress based on radially induced cracks are derived using the following formulas:

[0098]

[0099] In equation (6), ν is Poisson's ratio, dimensionless; α is the effective stress coefficient, dimensionless; E is Young's modulus, in GPa; α m It is the coefficient of thermal expansion of rock, in °C. -1 ;P w P is the pressure of the fluid column inside the well, in MPa. p T0 is the initial pore pressure of the formation, in MPa; T0 is the initial temperature of the formation, in °C; T w σ is the bottom hole circulation temperature of the drilling fluid, in °C. t It is the tensile strength of the formation, measured in MPa.

[0100] The upper and lower limit constraint lines of the maximum horizontal stress in radially induced fractures mentioned above pass through the wellbore stress component σ under horizontal well conditions according to equation (1). θθ and σ zz The minimum value σ is obtained when θ = 0°. θθmin and σ zzmin And satisfy σ zzmin ≤-σ t and σ zzmin ≤σ θθmin We obtain the circumferential normal stress component σ. θθ The minimum value σ θθmin and axial normal stress component σ zz The minimum value σ zzmin The calculation method is as follows:

[0101]

[0102] In equation (7), σ θθmin and σ zzmin σ is the circumferential normal stress component under horizontal well conditions. θθ and axial normal stress component σ zz The minimum value at θ = 0°, in MPa.

[0103] Equation (7) above satisfies two constraint conditions σ zzmin ≤-σ t and σ zzmin ≤σ θθmin Equation (6) is obtained based on the upper and lower limit constraint lines of the maximum horizontal stress in radially induced cracks.

[0104] In this embodiment, the wellbore direction of the horizontal well is along the direction of minimum horizontal stress, where the direction of minimum horizontal stress is 0°. Substituting equation (3) into equation (6) yields the upper and lower limit constraint lines of the maximum horizontal stress of radially induced fractures when the wellbore of the horizontal well in this embodiment is along the direction of minimum horizontal stress:

[0105]

[0106] Equation (8) above can be further expressed as the following equation:

[0107]

[0108] In the formula: ν is Poisson's ratio, dimensionless; α is the effective stress coefficient, dimensionless; E is Young's modulus, GPa; α m It is the coefficient of thermal expansion of rock, in °C. -1 ;P w P is the pressure of the fluid column inside the well, in MPa; p T is the initial pore pressure of the formation, in MPa; T0 is the initial temperature of the formation, in °C; T w It is the bottom hole circulation temperature of the drilling fluid, in °C; σ t It is the tensile strength of the formation, in MPa; These are the lower and upper limits of the maximum horizontal ground stress, respectively, in MPa.

[0109] Figure 3 The equations (4), (5), and (9) are shown with σ on the horizontal axis. h / σ V The vertical axis is σ. H / σ V The stress polygon and upper and lower limit constraint lines of the maximum horizontal geostress in this embodiment are drawn in the coordinate system under the horizontal well state.

[0110] (e) Based on the minimum horizontal ground stress σ h Respectively compared with the maximum horizontal ground stress σ H The intersection of the upper and lower limit constraint lines determines the upper and lower limits of the maximum horizontal ground stress.

[0111] from Figure 3 Minimum horizontal stress σ h With vertical ground stress σ V The ratio σ h / σ V σ h / σ V Find the intersection of σ = 0.68 with the upper and lower limit constraint lines, and locate σ on the vertical axis. H / σ V Ratio range σ H / σ V=0.71~0.87, indicated by two blue lines and two black lines with arrows in the figure. Further, the ratio σ is introduced from the vertical ground stress of 93.6 MPa. H / σ V The maximum horizontal stress range of the horizontal well in this embodiment is 66.5 to 81.4 MPa.

[0112] The beneficial effect of this invention is that by simply using radially induced fractures in a horizontal well to establish a stress polygon and upper and lower limit constraint lines for the maximum horizontal stress, and combining this with the minimum horizontal stress, the range of the maximum horizontal stress can be easily predicted. At the same time, this invention is applicable to the prediction and analysis of the maximum horizontal stress in different lithological strata.

[0113] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All features or steps in the disclosed methods or processes may be combined in any way, except for mutually exclusive features and / or steps.

Claims

1. A method for determining the maximum horizontal geostress under horizontal well conditions, characterized in that... Includes the following steps: (a) Collect imaging logging data of the target formation and determine whether there are radially induced fractures on the wellbore of the horizontal well based on the imaging logging data. If there are radially induced fractures, proceed to step (b). (b) Calculate the vertical ground stress separately. σ V Maximum horizontal ground stress σ H and minimum horizontal stress σ h Components on the wall of a horizontal well σ x , σ y , σ z ; (c) Calculate the radial normal stress components on the wellbore wall under horizontal well conditions based on the wellbore direction and the results of step (b). σ rr Circumferential normal stress components σ θθ and axial normal stress components σ zz And calculate the circumferential normal stress components. σ θθ minimum value σ θθmin and axial normal stress components σ zz minimum value σ zzmin ; (d) Draw a stress polygon of the target formation based on the stress of the target formation. Within the range of the drawn stress polygon, draw the upper and lower limit constraint lines of the maximum horizontal stress based on the radially induced fracture based on the results of step (c). (e) Based on the minimum horizontal stress σ h Respectively compared with the maximum horizontal ground stress σ H The intersection of the upper and lower limit constraint lines determines the upper and lower limits of the maximum horizontal ground stress. The stress polygon of the target formation is located at the minimum horizontal stress. σ h and vertical ground stress σ V ratio σ h / σ V The horizontal axis is defined by the maximum horizontal ground stress. σ H and vertical ground stress σ V ratio σ H / σ V It is plotted in a coordinate system with the vertical axis as the coordinate system; The specific process for determining the upper and lower limits of the maximum horizontal ground stress is as follows: first, by using the minimum horizontal ground stress... σ h With vertical ground stress σ V ratio σ h / σ V Find the intersection point with the upper and lower limit constraint lines of the maximum horizontal ground stress, and locate the maximum horizontal ground stress on the vertical axis. σ H With vertical ground stress σ V The range of ratios σ H / σ V Then the vertical stress σ V Substitute into the determined range of ratios σ H / σ V This yields the upper and lower limits of the maximum horizontal ground stress. In step (c), the radial normal stress component on the horizontal wellbore wall σ rr Circumferential normal stress components σ θθ and axial normal stress components σ zz The calculation method is as follows: （2） In equation (2), θ It is the well perimeter angle, in degrees; P p It is the formation pore pressure, in MPa; P w It is the pressure of the fluid column inside the well, in MPa; α It is the effective stress coefficient, which is dimensionless; ν is Poisson's ratio, which is dimensionless; E It is Young's modulus, measured in GPa. α m It is the coefficient of thermal expansion of the geological strata, in °C. -1 ; T 0 represents the initial temperature of the formation, in °C. T w This is the bottom hole circulation temperature of the drilling fluid, in °C. In step (d), the stress polygon of the target stratum is drawn using the following formula: （4） In equation (4), α It is the effective stress coefficient, which is dimensionless; P p It is the formation pore pressure, in MPa; μ f This represents the fault friction coefficient, which is dimensionless.

2. The method for determining the maximum horizontal geostress under horizontal well conditions according to claim 1, characterized in that: In step (b), vertical ground stress σ V Maximum horizontal ground stress σ H and minimum horizontal stress σ h Components on the wall of a horizontal well σ x , σ y , σ z The calculation method is as follows: （1） In equation (1), β b The azimuth angle is the well inclination angle, in degrees.

3. The method for determining the maximum horizontal geostress under horizontal well conditions according to claim 1, characterized in that: In step (c), the minimum value σ θθmin Through circumferential normal stress components σ θθ exist θ The minimum value is obtained when =0°. σ zzmin Through axial normal stress component σ zz exist θ The minimum value is obtained when =0°. σ θθmin and minimum value σ zzmin The calculation method is as follows: （3） In equation (3), σ θθmin and σ zzmin Circumferential normal stress components under horizontal well conditions σ θθ and axial normal stress components σ zz exist θ The minimum value at 0°, in MPa.

4. The method for determining the maximum horizontal in-situ stress under horizontal well conditions according to claim 1, characterized in that: The method for calculating the fault friction coefficient is as follows: （5） In equation (5), ν It is Poisson's ratio, which is dimensionless.

5. The method for determining the maximum horizontal geostress under horizontal well conditions according to claim 3, characterized in that: In step (d), in the circumferential normal stress component σ θθ minimum value σ θθmin and axial normal stress components σ zz minimum value σ zzmin Under the premise of satisfying the constraints, based on the radial normal stress components σ rr Circumferential normal stress components σ θθ and axial normal stress components σ zz Draw the upper and lower limit constraint lines for the maximum horizontal geostress based on radially induced fractures.

6. The method for determining the maximum horizontal in-situ stress under horizontal well conditions according to claim 5, characterized in that: In step (d), the upper and lower limit constraint lines of the maximum horizontal in-situ stress based on the radially induced crack are drawn using the following formula: （6） In equation (6), the circumferential normal stress component σ θθ minimum value σ θθminn and axial normal stress components σ zz minimum value σ zzmin The constraints that are satisfied are σ zzmin ≤- σ t and σ zzmin ≤ σ θθmin .

7. The method for determining the maximum horizontal in-situ stress under horizontal well conditions according to claim 1, characterized in that: In step (a), the basis for determining whether there are radially induced fractures on the wellbore of a horizontal well is the presence of a set of approximately parallel and discontinuous dark short straight lines on the imaging logging data.

8. The method for determining the maximum horizontal in-situ stress under horizontal well conditions according to claim 1, characterized in that: In step (b), vertical ground stress σ V The minimum horizontal geostress can be calculated by integrating density logging data. σ h It can be obtained through hydraulic fracturing or formation leakage tests.

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