A method for calculating ground stress based on full-process formation drain test of directional well

Abstract

The application provides a method for calculating the ground stress based on the whole process formation leak-off test of a directional well, comprising the following steps: performing the whole process formation leak-off test on the target directional well and recording the test data; calculating the horizontal minimum ground stress and the overburden pressure according to the test data of the whole process formation leak-off test and the rock mechanics characteristic parameters of the target directional well; calculating the fracture pressure value under all possible arrangement combinations of the horizontal maximum ground stress and the horizontal minimum ground stress at the well deviation azimuth of the target directional well according to the stress distribution around the well section of the formation leak-off test well and the tensile failure criterion; drawing the contour map of the fracture pressure to establish the ground stress query chart of the target directional well; and querying the horizontal maximum ground stress corresponding to the calculated horizontal minimum ground stress in the ground stress query chart. The application calculates the ground stress based on the test data of the whole process formation leak-off test of the target directional well, and effectively improves the accuracy of the calculation result of the ground stress size.

Description

Technical Field

[0001] This invention relates to the technical field of rock mechanics in petroleum engineering and wellbore stability research in oil and gas well engineering, and in particular to a method for calculating geostress based on formation leakage tests throughout the entire process of directional wells. Background Technology

[0002] Traditional methods for calculating geostress are generally based on the interpretation of geophysical well logging data. While the trends in well logging data can effectively characterize parameters such as formation pressure and formation fluid properties, they often contain significant errors in characterizing geostress. This is especially true for intermediate geostress; the current mainstream method is to take the average of the maximum and minimum geostress, but this often does not reflect actual conditions and results in substantial errors. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for calculating in-situ stress based on a full-process formation leakage test of directional wells, which can accurately obtain the in-situ stress.

[0004] To achieve the above objectives, this invention provides a method for calculating geostress based on a full-process formation leakage test of a directional well, wherein the geostress includes the minimum horizontal geostress σ. h Maximum horizontal ground stress σ H and the geostress σ of the overlying strata v The method for calculating geostress includes the following steps:

[0005] S1. Conduct a full-process ground leakage test on the target directional well and record the test data of the formation ground leakage of the target directional well throughout the entire process;

[0006] S2. Obtain the leak test curve of the target directional well based on the test data, and calculate the leakage pressure P based on the leak test curve. L Formation fracture pressure P F Crack propagation pressure P E Crack closure pressure P C and crack retension pressure P R ;

[0007] S3, Calculate the minimum horizontal ground stress σ h And the tensile strength of rock S t σ h =P C S t =P F -P R ;

[0008] S4. Obtain the rock mechanical characteristic parameters of the target directional well, and calculate the cohesion CS and internal friction angle φ of the current formation rock:

[0009] In the formula, V p1 The current ground acoustic velocity is given by m, where m is the regional correction factor.

[0010] S5. Calculate the pressure OBG in the overlying strata:

[0011] In the formula, V p2 ρ represents the stratigraphic velocity or inversion velocity. w ρ is the density of seawater. i h1 is the formation density, g is the gravitational acceleration, a and b are constants, h2 is the water depth, h3 is the starting vertical depth of the density logging data, and h3 is the vertical depth of the measuring point.

[0012] Overlying strata geostress σ v =Overlying strata pressure OBG;

[0013] S6. Based on the wellbore stress distribution and tensile failure criterion of the formation leakage test well section, and based on the aforementioned minimum horizontal stress σ h Rock tensile strength S t The cohesion CS and internal friction angle φ of the current strata rocks, and the geostress σ of the overlying strata. v Calculate the maximum horizontal ground stress σ at the inclination azimuth of the target directional well. H Horizontal minimum ground stress σ h The burst pressure P under all possible combinations of conditions f ;

[0014] S7. Draw the maximum horizontal geostress σ under the inclination azimuth of the target directional well. H Horizontal minimum ground stress σ h A contour map of the fracture pressure under all possible permutations and combinations is used to establish a geostress lookup chart for the target directional well.

[0015] S8. Based on the minimum horizontal ground stress σ calculated in step S3, h In the geostress query chart, look up the minimum geostress σ at that level. h The corresponding maximum horizontal ground stress σ H .

[0016] This application calculates in-situ stress based on experimental data from a full-process ground leakage test of a target directional well. The experimental data from the full-process ground leakage test is strongly correlated with the mechanical strength characteristics of the formation rock and the in-situ stress state, and can truly reflect the formation rock conditions. Compared with well logging data, the in-situ stress is interpreted more directly and reliably, ultimately improving the accuracy of the in-situ stress calculation results.

[0017] In the above technical solution, the preferred steps for the full-process ground leakage test of the target directional well are as follows: Step S1 includes the following sub-steps:

[0018] S11. During the entire process of the floor drain test, the corresponding pump pressure and injection volume shall be recorded every 20-50L pumping volume, or the corresponding pump pressure and time shall be recorded every 10s.

[0019] S12. After fracturing the formation, continue pumping until a stable pressure section is recorded, then stop pumping. Record the pump pressure every 10 seconds after stopping pumping until a stable pump pressure section is recorded. After the pump pressure is relatively stable, restart pumping to fracture the formation and continue pumping drilling fluid until a stable pressure section appears again, then stop pumping. Record the re-tension pressure every 10 seconds.

[0020] S13. Record the pressure and discharge changes during the entire process of the ground drain test. The test data of the formation ground drain of the target directional well includes the fracture pressure value, fracture extension pressure, instantaneous pump stop start pressure, inflection point of pressure drop after pump stop, fracture re-tension pressure after pump restart, and fracture extension pressure.

[0021] In the above technical solution, the leakage pressure P L Formation fracture pressure P F Crack propagation pressure P E Crack closure pressure P C and crack retension pressure P R The preferred calculation method is as follows: Step S2 includes the following sub-steps:

[0022] S21. Read the leakage pressure P displayed on the leak test curve. GL Formation fracture apparent pressure P GF Crack extension apparent pressure P GE Crack closure pressure P GC and the apparent pressure P of the crack retension GR ;

[0023] S22, the leakage pressure P L For: P L =P GL +0.00981ρH;

[0024] The formation fracturing pressure P F For: P F =P GF +0.00981ρH;

[0025] The crack propagation pressure P E For: P E =P GE +0.00981ρH;

[0026] The crack closure pressure P C For: P C =PGC +0.00981ρH;

[0027] The crack retension pressure P R For: P R =P GR +0.00981ρH;

[0028] In the above formula, ρ is the drilling fluid density, and H is the vertical depth of the test leak layer.

[0029] In the above technical solution, in step S4, the current formation acoustic velocity V p1 The preferred methods for obtaining it are as follows:

[0030] Method 1: Collect core samples from the formation drain test section of the target directional well and measure them directly through indoor triaxial tests.

[0031] Method 2: Collect acoustic logging data of the target directional well and use the acoustic data to obtain the result.

[0032] Method 3: Collect acoustic logging data from the nearest neighboring well to the target directional well, and use the acoustic data to obtain the result.

[0033] In the above technical solution, step S6 includes the following sub-steps:

[0034] S61, Order:

[0035]

[0036] In the formula, ψ is the well inclination angle, θ is the well perimeter angle with a value of 0 to 2π, Ω is the well inclination azimuth angle relative to the direction of the maximum horizontal ground stress, and ν is Poisson's ratio;

[0037] The three principal stresses on the wall of the inclined shaft are expressed as follows:

[0038]

[0039] In the formula, p i p is the drilling fluid column pressure. p Where K is the formation pressure, and K is the wellbore permeability coefficient, with a value ranging from 0 to 1;

[0040] make:

[0041] S62. Directional wellbore shear and tensile failure criteria:

[0042] Rock shear failure criterion: (σ1-σ3)-sinφ(σ1+σ3-2αp) p -2CScosφ=0;

[0043] Criterion for tensile failure of rock: σj -αp p +|S t | = 0;

[0044] S63. Drilling fluid density p that satisfies the shear failure criterion in step S62. i for:

[0045] p i =F1(σ v ,σ H ,σ h ,φ,CS,P p ,α,Ω,Ψ,θ);

[0046] Drilling fluid density p that satisfies the tensile failure criterion in step S62 i for:

[0047] p i =F2(σ v ,σ H ,σ h ,S t ,P p ,α,Ω,Ψ,θ);

[0048] In the formula, α is the effective stress coefficient;

[0049] S64. Calculate the maximum horizontal geostress σ at the inclination azimuth of the target directional well. H Horizontal minimum ground stress σ h Rupture pressure P under all possible combinations of conditions f :

[0050] (1) When σ j >σ i >σ k When the well perimeter angle satisfies hour,

[0051] By p i =F1(σ v ,σ H ,σ h ,φ,CS,P p The minimum p around the well is calculated using the formulas α, Ω, Ψ, θ. i Value, denoted as

[0052] (2) When σ i >σ j >σ k When the well perimeter angle satisfies hour,

[0053] By p i =F1(σ v ,σH ,σ h ,φ,CS,P p The minimum p around the well is calculated using the formulas α, Ω, Ψ, θ. i Value, denoted as

[0054] (3) When the value of the well perimeter angle satisfies hour,

[0055] By p i =F2(σ v ,σ H ,σ h ,S t ,P p The minimum p around the well is calculated using the formulas α, Ω, Ψ, θ. i Value, denoted as

[0056] (4) Rupture pressure P f for:

[0057] As described above, the geostress calculation method based on the full-process formation leakage test of directional wells, which relates to the present invention, has the following beneficial effects:

[0058] This application calculates in-situ stress based on experimental data from a full-process ground leakage test of a target directional well. The experimental data from the full-process ground leakage test is strongly correlated with the mechanical strength characteristics of the formation rock and the in-situ stress state, and can truly reflect the formation rock conditions. Compared with well logging data, the in-situ stress is interpreted more directly and reliably, ultimately improving the accuracy of the in-situ stress calculation results. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the leak test curve.

[0060] Figure 2 This is a schematic diagram of the leak test curve of the newly drilled adjustment well K-B6 in a specific embodiment of this application.

[0061] Figure 3 This is a cross-sectional view along the wellbore of the newly drilled adjustment well K-B6 in a specific embodiment of this application, showing the cohesion CS and internal friction angle φ.

[0062] Figure 4 This is a geostress lookup chart for the newly drilled adjustment well K-B6 in a specific embodiment of this application. Detailed Implementation

[0063] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0064] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0065] This application provides a method for calculating in-situ stress based on a full-process formation leakage test in a directional well. The in-situ stress includes the minimum horizontal in-situ stress σ. h Maximum horizontal ground stress σ H and the geostress σ of the overlying strata v That is, by following these steps and based on the experimental data from the formation leakage test throughout the directional well process, the minimum horizontal stress σ is calculated. h Maximum horizontal ground stress σ H and the geostress σ of the overlying strata v .

[0066] The geostress calculation method involved in this application specifically includes the following steps:

[0067] S1. Conduct a full-process ground leakage test in the well section specified in the drilling design, defining the well section as the target directional well; during the full-process ground leakage test of the target directional well, record the test data of the formation ground leakage throughout the entire process. The full-process ground leakage test includes the following steps:

[0068] S11. During the entire process of the floor drain test, record the corresponding pump pressure and injection volume every 20-50L pumping volume, or record the corresponding pump pressure and time every 10s (with constant pump speed).

[0069] S12. After fracturing the formation, continue pumping until a stable pressure section is recorded, then stop pumping. Record the pump pressure every 10 seconds after stopping pumping until a stable pump pressure section is recorded. After the pump pressure is relatively stable, restart pumping to fracture the formation and continue pumping drilling fluid until a stable pressure section appears again, then stop pumping. Record the re-tension pressure every 10 seconds.

[0070] S13. Record the pressure and discharge changes during the entire process of the ground drain test. The test data of the formation ground drain of the target directional well throughout the entire process includes the fracture pressure value, fracture extension pressure, instantaneous pump stop start pressure, inflection point of pressure drop after pump stop, fracture re-tension pressure after pump restart, and fracture extension pressure.

[0071] The pressure in the above steps can be obtained directly by reading the pressure displayed on the pressure gauge.

[0072] S2. Obtain the leak test curve of the target directional well based on the test data collected during the entire leak test process, such as... Figure 1 As shown. Read the leakage pressure P displayed on the leak test curve. GL Formation fracture apparent pressure P GF Crack extension apparent pressure P GE Crack closure pressure P GC and the apparent pressure P of the crack retension GR Among them, the leakage pressure P is shown on the instrument. GL The apparent pressure P represents the pressure at the inflection point where the leak test curve transitions from linear to nonlinear. GF The pressure indicated at the highest point of the leak test curve; the pressure indicated by crack propagation P. GE The stable apparent pressure after the instantaneous drop in the nonlinear segment of the leak test curve; the apparent pressure P at crack closure. GC The pressure displayed at the moment the pump is shut off; the pressure displayed P for crack re-tensioning. GR This is the pressure displayed at the moment the pump is started.

[0073] Calculate leakage pressure P L Formation fracture pressure P F Crack propagation pressure P E Crack closure pressure P C and crack retension pressure P R Specifically:

[0074] (1) Leakage pressure P L :

[0075] P L =P GL +0.00981ρH (1)

[0076] (2) Formation fracture pressure P F for:

[0077] P F =P GF +0.00981ρH (2)

[0078] (3) Crack propagation pressure P E for:

[0079] PE =P GE +0.00981ρH (3)

[0080] (4) Crack closure pressure P C for:

[0081] P C =P GC +0.00981ρH (4)

[0082] (5) Crack retension pressure P R for:

[0083] P R =P GR +0.00981ρH (5)

[0084] In equations (1) to (5) above, the unit of each pressure is MPa, and ρ is the drilling fluid density in g / cm³. 3 H represents the vertical depth of the test leak layer.

[0085] S3. Calculate the minimum horizontal in-situ stress σ based on the basic data from the formation leakage test throughout the entire process of the target directional well. h And the tensile strength of rock S t :

[0086] σ h =P C (6)

[0087] S t =P F -P R (7)

[0088] S4. Obtain the rock mechanical characteristic parameters of the target directional well. Based on the Lal empirical formula, calculate the cohesion CS and internal friction angle φ of the current formation rock:

[0089]

[0090]

[0091] In equations (8) and (9), V p1 denoted as the current ground acoustic velocity, and m as the regional correction coefficient.

[0092] Preferably, the current formation acoustic velocity V p1 The preferred methods for obtaining it are as follows:

[0093] Method 1: Collect core samples from the formation drain test section of the target directional well and measure them directly through indoor triaxial tests.

[0094] Method 2: In the absence of coring in the target directional well, collect sonic logging data from the target directional well and use this sonic data to obtain the result.

[0095] Method 3: In cases where the target directional well has not undergone coring or logging, collect sonic logging data from the nearest drilled and utilized reservoir well. Use this sonic data to determine the current formation sonic velocity V under the original formation pressure. For example, based on the sonic transit time logging data DT (µs / ft), the current formation sonic velocity V can be obtained using the following conversion relationship. p1 :

[0096]

[0097] S5. Collect density logging data in the area where the target directional well is located, and calculate the overlying strata pressure (OBG) of the formation leakage test section. Since the mudline of offshore oil and gas wells is below sea level, the depth-density relationship of the upper formation cannot be obtained by regressing the density logging data of the lower section. Therefore, this application preferably uses the Gardener model to calculate the density curve of the shallow formation, and then integrates the complete density data to obtain the overlying strata pressure (OBG).

[0098]

[0099] In equation (11), V p2 ρ represents the stratigraphic velocity or inversion velocity. w ρ is the density of seawater. i h1 is the formation density, g is the gravitational acceleration, a and b are constants, h2 is the water depth, h3 is the starting vertical depth of the density logging data, and h3 is the vertical depth of the measuring point.

[0100] Overlying strata geostress σ v = Overlying strata pressure OBG.

[0101] S6. Based on the wellbore stress distribution and tensile failure criterion of the formation leakage test well section, and based on the minimum horizontal stress σ calculated in step S3... h And the tensile strength of rock S t The rock mechanics parameters calculated in step S4 (i.e., cohesion CS and internal friction angle φ) and the overlying strata stress σ calculated in step S5. v Calculate the maximum horizontal ground stress σ under the inclination azimuth of the target directional well. H Horizontal minimum ground stress σ h The burst pressure P under all possible combinations of conditions f Specifically, it includes the following steps:

[0102] S61. Construct a wellbore stability model for the target directional well, and let:

[0103]

[0104] In equation (12), ψ is the well inclination angle, θ is the well perimeter angle with a value of 0 to 2π, Ω is the well inclination azimuth angle relative to the direction of maximum horizontal geostress, ν is Poisson's ratio, and σ h For the minimum horizontal ground stress, σ H For the maximum horizontal ground stress, σ v This represents the geostress of the overlying rock strata.

[0105] The three principal stresses on the wall of the inclined shaft are expressed as follows:

[0106]

[0107] In equation (13), p i p is the drilling fluid column pressure. p Where is the formation pressure, and K is the wellbore permeability coefficient, with a value ranging from 0 to 1.

[0108] make:

[0109]

[0110] S62. Directional wellbore shear and tensile failure criteria:

[0111] Criteria for rock shear failure:

[0112] (σ1-σ3)-sinφ(σ1+σ3-2αp p )-2CScosφ=0 (15)

[0113] Criteria for tensile failure of rock:

[0114] σ j -αp p +|S t |=0 (16)

[0115] In the case of directional wells, the triaxial principal stresses on the wellbore can be calculated using equation (13). The fracturing pressure is determined by both the triaxial principal stress state and the failure criterion. When the triaxial principal stress state satisfies the shear failure criterion, the wellbore collapses; when the triaxial principal stress state satisfies the tensile failure criterion, the wellbore fractures tensilely. From equations (12-15), the fracturing pressure P of a directional well is... f Triaxial geostress (σ) H σ h and σ v Rock mechanical strength (internal friction angle φ and internal cohesion CS), formation pressure p p Functions of wellbore circumference angle θ, wellbore inclination angle ψ, and wellbore azimuth angle Ω.

[0116] S63. Drilling fluid density p that satisfies the shear failure criterion in step S62. ifor:

[0117] p i =F1(σ v ,σ H ,σ h ,φ,CS,P p ,α,Ω,Ψ,θ) (17)

[0118] Drilling fluid density p that satisfies the tensile failure criterion in step S62 i for:

[0119] p i =F2(σ v ,σ H ,σ h ,S t ,P p ,α,Ω,Ψ,θ) (18)

[0120] In equations (17) and (18), α is the effective stress coefficient.

[0121] S64. Calculate the maximum horizontal ground stress σ under the inclination azimuth of the target directional well. H Horizontal minimum ground stress σ h Rupture pressure P under all possible combinations of conditions f :

[0122] (1) When σ j >σ i >σ k When the well perimeter angle satisfies hour,

[0123] From equation (17)p i =F1(σ v ,σ H ,σ h ,φ,CS,P p The minimum p around the well is calculated using the formulas α, Ω, Ψ, θ. i Value, denoted as

[0124] (2) When σ i >σ j >σ k When the well perimeter angle satisfies hour,

[0125] From equation (17)p i =F1(σ v ,σ H ,σ h ,φ,CS,P p The minimum p around the well is calculated using the formulas α, Ω, Ψ, θ. i Value, denoted as

[0126] (3) When the value of the well perimeter angle satisfies hour,

[0127] From equation (18)p i =F2(σ v ,σ H ,σ h ,S t ,P p The minimum p around the well is calculated using the formulas α, Ω, Ψ, θ. i Value, denoted as

[0128] (4) Rupture pressure P f for:

[0129] S7. Draw the maximum horizontal ground stress σ under the inclination azimuth of the target directional well. H Horizontal minimum ground stress σ h Contour maps of rupture pressure under all possible combinations, based on the maximum horizontal stress σ. H and the minimum horizontal ground stress σ h All possible permutations and combinations are used to create a geostress lookup chart for the target directional well.

[0130] S8. Based on the minimum horizontal ground stress σ calculated in step S3. h In the geostress query chart, look up the minimum geostress σ at that level. h The corresponding maximum horizontal ground stress σ H .

[0131] This application calculates in-situ stress based on experimental data from a full-process ground leakage test of a target directional well. The experimental data from the full-process ground leakage test is strongly correlated with the mechanical strength characteristics of the formation rock and the in-situ stress state, and can accurately reflect the formation rock conditions. Compared with well logging data, the in-situ stress interpretation is more direct and reliable, ultimately improving the accuracy of the in-situ stress calculation results. Furthermore, the development of highly deviated wells and extended-range wells is a trend in drilling technology, making the in-situ stress calculation method based on a full-process formation ground leakage test of a directional well, as described in this application, universally applicable in practical applications.

[0132] Furthermore, the following provides a specific application example of the geostress calculation method based on a full-process formation leakage test of a directional well. The K gas field in the western slope zone of the Xihu Depression in the Donghai Sea was put into production in 2015. The geological strata of this gas field, from top to bottom, are the Donghai Formation, Santan Formation, Liulang Formation, Longjing Formation, Huagang Formation, Pinghu Formation, and Baoshi Formation, with the reservoirs being the Huagang Formation and Pinghu Formation. In 2022, a new adjustment well, K-B6, underwent a full-process leakage test at a vertical depth of 2324m. To accurately describe the geostress situation in this block, the following calculation steps were performed according to this application.

[0133] Step 1: Based on the test data from the entire drain test, plot the pump pressure-pump flow rate leak curve, such as... Figure 2 As shown.

[0134] Read the leakage pressure P from the leak test curve. GL Formation fracture apparent pressure P GF Crack extension apparent pressure P GE Crack closure pressure P GC and the apparent pressure P of crack retension GR And calculate the leakage pressure P. L Formation fracture pressure P F Crack propagation pressure P E Crack closure pressure P C and crack retension pressure P R The calculation results are shown in Table 1. During the entire drain test, the drilling fluid density ρ was 1.25 g / cm³. 3 .

[0135] Table 1

[0136]

[0137]

[0138] Thus, the leakage pressure P L The formation fracture pressure P is 41.30 MPa. F The crack propagation pressure P is 43.16 MPa. E The crack closure pressure P is 35.66 MPa. C The crack re-tension pressure P is 35.01 MPa. R It is 36.00 MPa.

[0139] Step 2: Calculate the minimum horizontal geostress σ h And the tensile strength of rock S t .

[0140] Horizontal minimum ground stress σ h σ h =P C =35.01.

[0141] Rock tensile strength S t :S t =P F -P R =43.16-36=7.16.

[0142] Thus, the minimum horizontal ground stress σ h The tensile strength of the rock is 35.01 MPa. t It is 7.16 MPa.

[0143] Step 3: Calculate the rock mechanical characteristic parameters. Based on the Lal empirical formula, the cohesion CS and internal friction angle φ of the current formation rock are calculated along the wellbore profile, as shown below. Figure 3 As shown. From the cohesive force CS and the internal friction angle φ along the wellbore profile, the cohesive force CS is 11 MPa and the internal friction angle φ is 33°.

[0144] Step 4: Calculate the overlying strata pressure OBG. The K gas field is located in the Xihu Depression of the East China Sea. Shallow formation density logging data is lacking. Therefore, the widely used shallow formation density fitting model, the Gardener model, is used to fit the shallow formation density. The seawater density ρ... w It is 1.07 g / cm³ 3 The calculated pressure OBG of the overlying strata is 51.30 MPa.

[0145] Step 5: Based on the well trajectory parameters, the well inclination angle ψ of the 2324m vertical depth section is 39.5°, and the well inclination azimuth angle Ω is 127.53°. According to step S6 above, the triaxial principal stresses obtained from the wellbore stress distribution are substituted into the shear and tensile judgment criteria to obtain the fracture pressure P. f .

[0146] Step 6: Draw the in-situ stress-fracture pressure calculation chart, which is also the in-situ stress lookup chart for the target directional well, such as... Figure 4 As shown.

[0147] Step 7: Based on the minimum horizontal ground stress σ h The maximum horizontal ground stress σ corresponding to 35.01 MPa is found in the ground stress lookup chart. H It is 44.15 MPa.

[0148] This completes the calculation of ground stress.

[0149] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0150] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for calculating in-situ stress based on a full-process formation leakage test in a directional well, wherein the in-situ stress includes the minimum horizontal in-situ stress. Maximum horizontal ground stress and the geostress of the overlying strata Its features are: The method for calculating geostress includes the following steps: S1. Conduct a full-process ground leakage test on the target directional well and record the test data of the formation ground leakage of the target directional well throughout the entire process; S2. Obtain the leak test curve of the target directional well based on the test data, and calculate the leakage pressure based on the leak test curve. Formation fracture pressure Crack propagation pressure Crack closure pressure and crack retension pressure ; S3, Calculate the minimum horizontal ground stress and rock tensile strength : , ; S4. Obtain the rock mechanical characteristic parameters of the target directional well, and calculate the cohesion CS and internal friction angle of the current formation rock. : , ; In the formula, The current ground acoustic velocity is given by m, where m is the regional correction factor. S5. Calculate the overlying strata pressure OBG: ; In the formula, This refers to the stratigraphic velocity or inversion velocity. The density of seawater, h1 is the formation density, g is the gravitational acceleration, a and b are constants, h2 is the water depth, h3 is the starting vertical depth of the density logging data, and h3 is the vertical depth of the measuring point. Overlying strata geostress =Overlying strata pressure OBG; S6. Based on the wellbore stress distribution and tensile failure criterion of the formation leakage test well section, and based on the aforementioned minimum horizontal stress... Rock tensile strength The cohesion CS and internal friction angle of the current strata rocks and the geostress of the overlying strata Calculate the maximum horizontal ground stress at the inclination azimuth of the target directional well. Minimum horizontal ground stress Rupture pressure values ​​under all possible combinations ; S7. Draw the maximum horizontal ground stress under the inclination azimuth of the target directional well. Minimum horizontal ground stress A contour map of the fracture pressure under all possible permutations and combinations is used to establish a geostress lookup chart for the target directional well. S8. Based on the minimum horizontal ground stress calculated in step S3. Query the minimum ground stress at that level in the ground stress query chart. Corresponding maximum horizontal ground stress .

2. The geostress calculation method according to claim 1, characterized in that: Step S1 includes the following sub-steps: S11. During the entire process of the floor drain test, the corresponding pump pressure and injection volume shall be recorded every 20-50L pumping volume, or the corresponding pump pressure and time shall be recorded every 10s. S12. After fracturing the formation, continue pumping until a stable pressure section is recorded, then stop pumping. Record the pump pressure every 10 seconds after stopping pumping until a stable pump pressure section is recorded. After the pump pressure is relatively stable, restart pumping to fracture the formation and continue pumping drilling fluid until a stable pressure section appears again, then stop pumping. Record the re-tension pressure every 10 seconds. S13. Record the pressure and discharge changes during the entire process of the ground drain test. The test data of the formation ground drain of the target directional well includes the fracture pressure value, fracture extension pressure, instantaneous pump stop start pressure, inflection point of pressure drop after pump stop, fracture re-tension pressure after pump restart, and fracture extension pressure.

3. The geostress calculation method according to claim 1, characterized in that: Step S2 includes the following sub-steps: S21. Read the leakage pressure displayed on the leak test curve. Formation fracture apparent pressure Crack extension and apparent pressure Crack closure pressure and crack retension apparent pressure ; S22, the leakage pressure for: ; The formation fracturing pressure for: ; The crack extension pressure for: ; The crack closure pressure for: ; The crack retension pressure for: ; In the above formula, H represents the drilling fluid density, and H represents the vertical depth of the test leak layer.

4. The geostress calculation method according to claim 1, characterized in that: In step S4, the current formation acoustic velocity The method of obtaining the data is as follows: core samples are collected from the formation drain test section of the target directional well and directly measured through indoor triaxial tests.

5. The geostress calculation method according to claim 1, characterized in that: In step S4, the current formation acoustic velocity The method of obtaining the data is as follows: collect the acoustic logging data of the target directional well and use the acoustic logging data to obtain the data.

6. The geostress calculation method according to claim 1, characterized in that: In step S4, the current formation acoustic velocity The method for obtaining the data is as follows: collect the acoustic logging data of the nearest neighboring well to the target directional well, and use the acoustic logging data to obtain the data.

7. The geostress calculation method according to claim 1, characterized in that: Step S6 includes the following sub-steps: S61, Order: ； In the formula, The well inclination angle, The well perimeter angle, with a value of , The wellbore inclination azimuth is relative to the direction of maximum horizontal ground stress. Poisson's ratio; The three principal stresses on the wall of the inclined shaft are expressed as follows: ； In the formula, This refers to the drilling fluid column pressure. Where K is the formation pressure, and K is the wellbore permeability coefficient, with a value ranging from 0 to 1; make: ; S62. Directional wellbore shear and tensile failure criteria: Criteria for rock shear failure: ; Criteria for tensile failure of rock: ; S63. Drilling fluid density that satisfies the shear failure criterion in step S62. for: ； Drilling fluid density that satisfies the tensile failure criterion in step S62 for: ； In the formula, The effective stress coefficient; S64. Calculate the maximum horizontal ground stress at the inclination azimuth of the target directional well. Minimum horizontal ground stress Rupture pressure under all possible combinations : (1) When When the well perimeter angle satisfies hour, Depend on Calculate the minimum wellbore perimeter Value, denoted as ; (2) When When the well perimeter angle satisfies hour, Depend on Calculate the minimum wellbore perimeter Value, denoted as ; (3) When the value of the well perimeter angle satisfies hour, Depend on Calculate the minimum wellbore perimeter Value, denoted as ; (4) Rupture pressure for: .

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