CN106223918B - Method and device for obtaining fracture pressure of hydraulic fracturing - Google Patents

Abstract

Hydraulic fracturing fracture pressure preparation method and device provided in an embodiment of the present invention obtain stratum parameters and earth stress, pore fluid pressure value, casing mechanics parameter, cement sheath mechanics parameter and stratum dynamics parameter, and under the action of wellbore fluids pressure and crustal stress, casing stress field distributed model, cement sheath Stress Field Distribution model and formation stress field distributed model are established respectively.According to established casing stress field distributed model, cement sheath Stress Field Distribution model and formation stress field distributed model, the well circumferential stress field model under the conditions of the complete well of well-case perforating is established；Further according to well circumferential stress field model, hydraulic fracturing theory and fracture criteria, hydraulic fracturing fracture pressure is obtained.Compared with existing hydraulic fracturing fracture pressure preparation method, hydraulic fracturing fracture pressure preparation method Consideration provided in an embodiment of the present invention more comprehensively, closer to practical complete well situation.

Description

Method and device for obtaining fracture pressure of hydraulic fracturing

technical field

The invention relates to the field of petroleum engineering fracturing, in particular to a hydraulic fracturing fracture pressure obtaining method and device.

Background technique

In the process of oil and gas field development, especially in the development of low permeability oil and gas fields, casing perforation hydraulic fracturing is a necessary completion measure, and the accurate calculation of hydraulic fracturing fracture pressure has an important impact on the optimal design of hydraulic fracturing.

In the prior art, it is usually considered that there are tiny cracks between the cement sheath and the formation. During the fracturing process, the fracturing fluid directly enters the tiny cracks, which is inconsistent with the actual situation, which is not conducive to the hydraulic fracturing pressure. Calculate accurately.

Contents of the invention

In view of this, the embodiment of the present invention provides a hydraulic fracturing fracture pressure acquisition method and device to improve the hydraulic fracturing process, assuming that the fracturing fluid directly enters the tiny fractures, which is not conducive to the accurate calculation of the hydraulic fracturing fracture pressure. question.

In order to achieve the above purpose, an embodiment of the present invention provides a hydraulic fracturing fracture pressure obtaining method, the method comprising: obtaining formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters and formation mechanical parameters ; Under the action of wellbore fluid pressure and in-situ stress, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established; according to the casing stress field distribution model, the cement sheath stress field distribution model and the formation The stress field distribution model establishes the wellbore stress field model under the condition of casing perforation completion; the hydraulic fracturing fracture pressure is obtained according to the wellbore stress field model, hydraulic fracturing theory and fracture criteria.

The embodiment of the present invention also provides a hydraulic fracturing fracture pressure acquisition device, the device includes: a parameter acquisition module, used to obtain formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters and formation Mechanical parameters; the first model building module is used to respectively establish the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model under the action of wellbore fluid pressure and ground stress; the second model building module, It is used to establish the stress field model around the well under the condition of casing perforation completion according to the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model; the hydraulic fracturing fracture pressure acquisition module is used to The wellbore stress field model, hydraulic fracturing theory and fracture criterion are used to obtain the hydraulic fracturing fracture pressure.

The beneficial effects of the hydraulic fracturing fracture pressure obtaining method and device provided in the embodiments of the present invention are as follows:

The hydraulic fracturing fracture pressure obtaining method and device provided by the embodiments of the present invention obtain formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters, and formation mechanical parameters, and the effects of wellbore fluid pressure and ground stress Next, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established. According to the established casing stress field distribution model, cement sheath stress field distribution model and formation stress field distribution model, the wellbore stress field model under the condition of casing perforation completion is established; then according to the wellbore stress field model, hydraulic pressure Based on the fracture theory and fracture criterion, the fracture pressure of hydraulic fracturing is obtained. Compared with the existing methods for obtaining the hydraulic fracturing fracture pressure, the method for obtaining the hydraulic fracturing fracture pressure provided by the embodiment of the present invention improves the hydraulic fracturing fracture process, assuming that the fracturing fluid directly enters the tiny fractures during the fracturing process, which is not conducive to hydraulic fracturing fractures. The problem of accurate calculation of pressure.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a flow chart of the hydraulic fracturing fracture pressure obtaining method provided by the embodiment of the present invention;

Fig. 2 is the flowchart of the specific steps of step S100 shown in Fig. 1;

Fig. 3 is the flowchart of the specific steps of step S200 shown in Fig. 1;

Fig. 4 is the flowchart of the specific steps of step S220 shown in Fig. 3;

Fig. 5 is a schematic diagram of a casing-cement sheath-formation combination provided by an embodiment of the present invention;

Fig. 6 is a schematic diagram of the average geostress acting on the well circumference in an embodiment of the present invention;

Fig. 7 is a structural block diagram of a hydraulic fracturing pressure obtaining device provided by an embodiment of the present invention;

Fig. 8 is a structural block diagram of the parameter acquisition module shown in Fig. 7;

Fig. 9 is a structural block diagram of the first model building module shown in Fig. 7;

Fig. 10 is a structural block diagram of the horizontal ground stress model establishment sub-module shown in Fig. 9 .

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. The following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

Example

Please refer to FIG. 1 for details. FIG. 1 shows that the hydraulic fracturing fracture pressure obtaining method provided by the embodiment of the present invention includes the following steps S100 to S400:

Step S100, obtaining formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters and formation mechanical parameters.

Step S100 may specifically include the following steps S110 to S130, please refer to FIG. 2 for details:

Step S110, obtaining formation stress parameters and pore fluid pressure values according to data obtained after well logging.

Well logging, also known as geophysical well logging or mine geophysics, referred to as well logging, is a method of measuring geophysical parameters using the electrochemical properties, electrical conductivity, acoustic properties, radioactivity and other geophysical properties of rock formations, which belongs to applied geophysics. One of methods (including gravitational, magnetic, electric, seismic, nuclear).

Step S120, obtaining casing mechanical parameters and cement sheath mechanical parameters according to the data obtained after cementing.

Well cementing is an indispensable and important link in the process of drilling and completion operations, which includes casing running and cement injection. Cementing technology is a multi-disciplinary comprehensive application technology, which is systematic, one-time and short in time. The main purpose of cementing is to protect and support the casing in oil and gas wells, and to isolate formations such as oil, gas and water.

In step S130, formation mechanical parameters are obtained according to data obtained after well logging or through experimental tests on rocks.

The formation mechanical parameters can be obtained from the data obtained after well logging, or can be obtained by measuring the mechanical parameters of the rock through experiments. The specific method for obtaining the formation mechanical parameters should not be understood as a limitation of the present invention.

In step S200 , under the action of wellbore fluid pressure and ground stress, a casing stress field distribution model, a cement sheath stress field distribution model, and a formation stress field distribution model are respectively established.

Step S200 specifically includes the following steps S210 to S230, please refer to Figure 3 for details:

In step S210, under the sole action of the wellbore fluid pressure, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established.

The force system around the wellbore is divided into three parts: casing-cement sheath-formation. Please refer to Figure 5 for details. The stress field around the wellbore under the wellbore fluid pressure is obtained according to the Lame formula:

Among them, σ _r is the radial stress, σ _θ is the circumferential stress, r is the distance from any point in the formation to the center of the wellbore, (σ _ri ) _p is the radial stress under fluid pressure, (σ _θi ) _p is the fluid pressure For the circumferential stress under action, A _i and C _i are a coefficient without clear physical meaning, and i takes 1, 2, and 3, corresponding to the casing, cement sheath, and formation, respectively.

The plane strain relation is:

Among them, E is the elastic modulus under the plane stress condition, E _' is the elastic modulus under the plane strain condition, then _E'1 is the elastic modulus of the casing under the plane strain condition, and E'2 is the cement under the plane strain condition The elastic modulus of the ring, E' ₃ is the elastic modulus of the formation under the plane strain condition,

v is the Poisson's ratio under the plane stress condition, v' is the Poisson's ratio under the plane strain condition, then ν' ₁ is the Poisson's ratio of the casing under the plane strain condition, and ν' ₂ is the cement sheath under the plane strain condition Poisson's ratio, ν' ₃ is the Poisson's ratio of the formation under the plane strain condition.

The boundary conditions, stress continuity conditions and displacement continuity conditions are as follows:

Among them, r is the distance from any point in the formation to the center of the wellbore, R1 is the inner diameter _of the casing, R2 is the inner diameter _of the cement sheath, _R3 is the outer diameter of the cement sheath, _PW is the fluid pressure in the wellbore,

(σ _r1 ) _p is the radial stress of casing under fluid pressure, (σ _r2 ) _p is the radial stress of cement sheath under fluid pressure, (σ _r3 ) _p is the diameter of formation under fluid pressure axial stress, (u _r1 ) _p is the radial displacement of the casing under the fluid pressure, (u _r2 ) _p is the radial displacement of the cement sheath under the fluid pressure, (u _r3 ) _p is the radial displacement of the cement sheath under the fluid pressure Radial displacement of the ground.

Putting formula (3) into formula (1), the six unknown parameters in formula (1) can be obtained as follows:

The unknown parameters in formula (4) are expressed as follows:

Among them, R ₁ is the inner diameter of the casing, R ₂ is the inner diameter of the cement sheath, R ₃ is the outer diameter of the cement sheath, E' ₁ is the elastic modulus of the casing under the condition of plane strain, and E' ₂ is the elastic modulus of the casing under the condition of plane strain. The elastic modulus of the cement sheath, E' ₃ is the elastic modulus of the formation under the plane strain condition, ν' ₁ is the Poisson's ratio of the casing under the plane strain condition, and ν' ₂ is the Poisson's ratio of the cement sheath under the plane strain condition , ν' ₃ is the Poisson's ratio of the formation under the plane strain condition.

Combining formulas (1) to (5), the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model can be obtained under the single action of wellbore fluid pressure.

In step S220 , under the single action of horizontal ground stress, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established.

Considering the in-situ stresses σ _H and σ _h of the horizontal plane, the average in-situ stress σ and deviation in-situ stress S are introduced as follows:

Among them, σ _H is the horizontal maximum in situ principal stress, σ _h is the horizontal minimum in situ principal stress,

The horizontal far-earth stress field in polar coordinates is expressed as:

Among them, σ _r is the radial stress, τ _rθ is the tangential stress, and θ is the circumferential angle of the borehole.

Specifically, formula (7) can be decomposed into the following two boundary conditions to be solved respectively.

Boundary Condition A:

Boundary Condition B:

Solve the boundary condition A and boundary condition B separately and then superimpose, the stress effect caused by the horizontal maximum in situ principal stress σ _H and the horizontal minimum in situ principal stress σ _h on the horizontal plane can be obtained, please refer to Figure 4 for details, including the following steps S221 to S226 :

Step S221, solving the horizontal plane far-earth stress field under the boundary condition A.

The solution to the boundary condition A is similar to the previous fluid pressure in the wellbore, which can be regarded as the case of the combined cylinder shown in Fig. 6 .

According to the Lame formula, the stress field around the wellbore is set as:

Among them, σ _r is the radial stress, σ _θ is the circumferential stress, r is the distance from any point in the formation to the center of the wellbore, (σ _ri ) _p is the radial stress under fluid pressure, (σ _θi ) _p is the fluid pressure Circumferential stress under action, A _i and C _i are predictive parameters, i takes 1, 2, and 3, corresponding to the casing, cement sheath, and formation, respectively.

The boundary conditions, stress continuity conditions and displacement continuity conditions are as follows:

Among them, r is the distance from any point in the formation to the center of the wellbore, R ₁ is the inner diameter of the casing, R ₂ is the inner diameter of the cement sheath, R ₃ is the outer diameter of the cement sheath, (σ _ri ) _σ is the average in-situ stress Radial stress, (u _ri ) _σ is radial displacement.

Putting formula (11) into formula (10), the six unknown parameters in formula (10) can be obtained as follows:

A ₁ , A ₂ , A ₃ , and C ₁ , C ₂ , and C ₃ are all coefficients and have no clear physical meaning. Therefore, it should be understood that the specific values represented by the above coefficients in different scenarios may be different.

The parameters of equation (12) can be given by:

Among them, R ₁ is the inner diameter of the casing, R ₂ is the inner diameter of the cement sheath, R ₃ is the outer diameter of the cement sheath, E' ₁ is the elastic modulus of the casing under the condition of plane strain, and E' ₂ is the elastic modulus of the casing under the condition of plane strain. The elastic modulus of the cement sheath, E' ₃ is the elastic modulus of the formation under the plane strain condition, ν' ₁ is the Poisson's ratio of the casing under the plane strain condition, and ν' ₂ is the Poisson's ratio of the cement sheath under the plane strain condition , ν' ₃ is the Poisson's ratio of the formation under the plane strain condition, and σ is the average in-situ stress.

Combining Equation (10) to Equation (13), the far-earth stress field on the horizontal plane can be obtained under boundary condition A.

Step S222, solving the horizontal plane remote stress field under the boundary condition B.

Assuming a cylinder model with an inner radius r _a and an outer radius r _b , the boundary conditions are as follows:

r＝r _b ,σ _r ＝-S cos 2θ,τ _rθ ＝S sin 2θ (14)

Let the stress function Φ be:

Φ _(r,θ) = f _(r) cos 2θ (15a)

And because the stress component relationship can be expressed as:

Combining the stress function Φ and the stress component relation (15b), the general stress expression can be obtained:

Among them, σ _r is the radial stress, σ _θ is the circumferential stress, τ _rθ is the tangential stress, θ is the borehole circumferential angle, and A, B, C and D are coefficients, which have no clear physical meaning.

Step S223, obtaining the stress expression corresponding to the formation.

Comparing the stratum model with the stress expression formula (16), combined with formula (14), the stress expression corresponding to the stratum is obtained:

Among them, (σ _ri ) _s is the radial stress under deviated geostress, (σ _r3 ) _s is the radial stress of formation under deviated geostress; (σ _θi ) _s is the circumferential stress under deviated geostress. stress, (σ _θ3 ) _s is the circumferential stress of the formation under the action of deviated in-situ stress, τ _rθ3 is the tangential stress of the formation, (τ _rθ3 ) _s is the tangential stress of the formation under the action of deviated in-situ stress, and S ₁ is The radial load of the outer boundary of the cement sheath, S ₂ is the tangential load of the outer boundary of the cement sheath.

Step S224, obtaining the stress expression corresponding to the cement sheath.

The stress expression corresponding to the cement sheath is:

Among them, (σ _r2 ) _s is the radial stress of the cement sheath under the action of deviated ground stress, (σ _θ2 ) _s is the circumferential stress of the cement sheath under the action of deviated ground stress, (τ _rθ2 ) _s is the action of deviated ground stress The tangential stress of the cement sheath under , n ₁ , n ₂ , n ₃ , and n ₄ are coefficients, which have no clear physical meaning, and n ₁ , n ₂ , n ₃ , and n ₄ can be given by the following formula:

The relevant parameters in formula (19) are as follows:

Among them, S ₃ is the radial load of the casing, and S ₄ is the tangential load of the casing.

Step S225, obtaining the stress expression corresponding to the bushing.

The stress expression corresponding to the casing is:

Among them, (σ _r1 ) _s is the radial stress of the casing under the action of the deviated ground stress, (σ _θ1 ) _s is the circumferential stress of the casing under the action of the deviated ground stress, (τ _rθ1 ) _s is the action of the deviated ground stress The tangential stress of the lower casing, k ₁ , k ₂ , k ₃ , and k ₄ are coefficients with no clear physical meaning, and k ₁ , k ₂ , k ₃ , and k ₄ can be given by the following formula:

The relevant parameters in formula (22) are as follows:

Step S226, solving the unknown variables in the stress expression corresponding to the formation, the stress expression corresponding to the cement sheath, and the stress expression corresponding to the casing.

The stress expressions corresponding to formation, cement sheath and casing are respectively in formula (17), formula (18) and formula (21), formula (17), formula (18) and formula (21), S ₁ , S ₂ , S ₃ , S ₄ are unknown variables, which can be determined by displacement continuity conditions. Since the stress expression has been given, the strain can be integrated through the geometric equation, and the displacement expression can be obtained as follows:

At the interface between the casing and the cement sheath and at the interface between the cement sheath and the formation, the displacement continuity condition is:

r is the distance from any point to the center of the wellbore. The distance between the point at the interface between the casing and the cement sheath and the center of the wellbore is R ₂ , and the distance between the point at the interface between the cement sheath and the formation and the center of the wellbore is R ₃ . For details, please refer to See Figures 5 and 6.

Putting equation (25) into equation (24), the unknown variables S ₁ , S ₂ , S ₃ , and S ₄ can be solved:

The variables in equation (26) are given by:

The variables in equation (27) are given by:

The variables in equation (28) are given by equations (29) to (31):

in,

According to the combination of formula (6) to formula (32), the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model can be obtained under the single action of horizontal ground stress.

In step S230 , under the sole action of the vertical ground stress, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established.

The casing is:

(σ _z1 ) _V ＝ν ₁ (σ _r1 +σ _θ1 ) (33)

Among them, (σ _z1 ) _v is the z-direction stress of the casing under the action of the vertical in-situ stress, σ _r1 is the radial stress of the casing under the joint action of the fluid pressure in the wellbore, the average in-situ stress, and the deviation in-situ stress, and σ _θ1 is the circumferential stress of the casing under the joint action of the fluid pressure in the wellbore, the average in-situ stress, and the deviation in-situ stress, and v1 is the Poisson's ratio _of the casing.

The cement ring is:

(σ _z2 ) _V ＝ν ₂ (σ _r2 +σ _θ2 ) (34)

Among them, (σ _z2 ) _v is the z-direction stress of the cement sheath under the action of vertical in-situ stress, σ _r2 is the radial stress of the cement sheath under the joint action of fluid pressure in the wellbore, average in-situ stress, and deviation in-situ stress, σ _θ2 is the circumferential stress of the cement sheath under the joint action of the fluid pressure in the wellbore, the average in-situ stress, and the deviation in _- situ stress, and v2 is the Poisson's ratio of the cement sheath.

Strata are:

(σ _z3 ) _V ＝σ _V -ν ₃ (σ _H +σ _h )+ν ₃ (σ _r3 +σ _θ3 ) (35)

Among them, (σ _z3 ) _v is the z-direction stress of the formation under the action of vertical in-situ stress,

σ _v is the vertical stress, v ₃ is the Poisson's ratio of the formation, σ _H is the horizontal maximum in situ principal stress, σ _h is the horizontal minimum in situ principal stress, σ _r3 is the fluid pressure in the wellbore, the average in situ stress and the deviation in situ stress The radial stress of the formation under the combined action, σ _θ3 is the circumferential stress of the formation under the joint action of the fluid pressure in the wellbore, the average in-situ stress, and the deviation in-situ stress.

For a perforated well with casing running and cementing, the stress field around the wellbore can be superimposed by the stress field caused by the fluid pressure in the wellbore, the average in-situ stress, the deviation in-situ stress and the vertical stress:

Among them, τ _rθi is the tangential stress, τ _θzi is the hoop shear stress, τ _rzi is the radial shear stress, and σ _zi is the z-direction stress.

Step S300, according to the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model, establish a wellbore stress field model under the condition of casing perforation completion.

The stress field around the wellbore is treated as the in-situ stress, combined with the fluid pressure in the perforation and the filtration effect of fracturing fluid, the stress field around the perforation hole is obtained:

Among them, α _i is the Biot poroelastic coefficient, is the circumferential angle of the perforation hole, σ _si is the radial stress under the coordinates of the perforation hole, is the circumferential stress under the perforation coordinates, σ _zzi is the axial stress under the perforation coordinates, τ _szzi are the shear stress under the perforation hole coordinates, s is the perforation radius, P _p is the formation pore fluid pressure, and φ is the formation rock porosity.

Taking i=3 for formula (37), the corresponding stress field around the formation hole is obtained. Taking s=R, the stress distribution on the formation perforation wall can be obtained as:

From formula (38), it can be seen that due to is not zero, so with σ _zz3 not plane principal stress. The calculation of the principal stress is as follows:

Step S400, according to the wellbore stress field model, hydraulic fracturing theory and fracture criterion, hydraulic fracturing fracture pressure is obtained.

The fracture criterion for tensile fracture initiation along the rock body is:

σ ₁ -αP _p >S _t (40)

Among them, σ ₁ is the maximum principal stress, s _t is the rock tensile strength, α is the Biot coefficient, the principal stress of the hole wall is a function of the bottomhole flow pressure and position, and the bottomhole pressure P _w is gradually increased by using the trial and error method, when the formula ( 40), the cracks start to crack.

Table 1

For example, taking a fractured well with a depth of 2468 meters to 2502 meters as an example, its main parameters are shown in Table 1, and the parameters in Table 1 are brought into formula (1) to formula (36), and the casing-cement The stress of the ring-formation is based on this stress, and the three principal stresses of the hole wall are calculated by formula (39). During the calculation process, the bottom hole pressure P _w is gradually increased by using the trial algorithm, and the calculation ends when formula (40) is satisfied. The bottom hole pressure Pw at this time is the corresponding fracture pressure. The rupture pressure value measured on site is 54.5MPa, and the rupture pressure value calculated by this method is 52.8MPa, with a relative error of 3%, which proves the correctness of this method.

The hydraulic fracturing fracture pressure acquisition method provided by the embodiment of the present invention obtains the parameters required for calculation, respectively establishes the stress field model around the wellbore under the sole action of the wellbore fluid pressure, the stress field model around the wellbore under the sole action of the horizontal ground stress, and the vertical wellbore stress field model. Wellbore stress field model under the action of in-situ stress alone. The above three wellbore stress field models are superimposed by the principle of stress superposition to obtain the wellbore stress field model under the joint action of wellbore fluid pressure, horizontal in-situ stress and vertical in-situ stress. According to the stress field model around the wellbore under the joint action of wellbore fluid pressure, horizontal ground stress and vertical ground stress, the stress field of the perforation wall is established. On the basis of obtaining the stress field of the perforation hole wall, the fracture pressure of hydraulic fracturing is obtained according to the fracture criterion. Compared with existing calculation methods, the calculation process is more accurate.

Please refer to FIG. 7 for details. FIG. 7 shows a device for obtaining hydraulic fracturing pressure provided by an embodiment of the present invention. The device 100 includes:

The parameter obtaining module 110 is used to obtain formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters and formation mechanical parameters.

The first model establishing module 120 is configured to respectively establish a casing stress field distribution model, a cement sheath stress field distribution model, and a formation stress field distribution model under the effects of wellbore fluid pressure and ground stress.

The second model building module 130 is configured to establish a stress field model around the well under the condition of casing perforation completion according to the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model.

The hydraulic fracturing fracture pressure acquisition module 140 is configured to obtain the hydraulic fracturing fracture pressure according to the stress field model around the well, the hydraulic fracturing theory and the fracture criterion.

Please refer to FIG. 8 for details. FIG. 8 shows a structural block diagram of the parameter acquisition module 110. The parameter acquisition module 110 includes:

The first parameter acquisition sub-module 111 is used to obtain formation stress parameters and pore fluid pressure values according to data obtained after well logging.

The second parameter acquisition sub-module 112 is configured to acquire casing mechanical parameters and cement sheath mechanical parameters according to data obtained after cementing.

The third parameter obtaining sub-module 113 is used to obtain formation mechanical parameters according to data obtained after well logging or through experimental tests on rocks.

Please refer to FIG. 9 for details. FIG. 9 shows a structural block diagram of the first model building module 120. The first model building module 120 includes:

The wellbore fluid pressure model establishment sub-module 121 is used to respectively establish a casing stress field distribution model, a cement sheath stress field distribution model and a formation stress field distribution model under the sole action of the wellbore fluid pressure.

The horizontal ground stress model establishment sub-module 122 is used to respectively establish a casing stress field distribution model, a cement sheath stress field distribution model and a formation stress field distribution model under the single action of the horizontal ground stress.

The sub-module 123 for establishing a vertical ground stress model is used to respectively establish a casing stress field distribution model, a cement sheath stress field distribution model, and a formation stress field distribution model under the vertical ground stress alone.

Please refer to FIG. 10 for details. FIG. 10 shows a structural block diagram of the horizontal ground stress model building submodule 122. The horizontal ground stress model building submodule 122 includes:

The first solving sub-module 1221 is used to solve the far-earth stress field on the horizontal plane under the boundary condition A.

The second solving sub-module 1222 is used to solve the far-earth stress field on the horizontal plane under the boundary condition B.

The formation expression sub-module 1223 is used to obtain the stress expression corresponding to the formation.

The cement sheath expression sub-submodule 1224 is used to obtain the corresponding stress expression of the cement sheath.

The bushing expression sub-module 1225 is used to obtain the stress expression corresponding to the bushing.

The unknown variable solving sub-module 1226 is used to solve the unknown variables in the stress expression corresponding to the formation, the stress expression corresponding to the cement sheath, and the stress expression corresponding to the casing.

The devices for obtaining hydraulic fracturing fracture pressure shown in FIGS. 7 to 10 correspond to the methods for obtaining hydraulic fracturing fracture pressure shown in FIGS. 1 to 4 , and will not be repeated here.

The hydraulic fracturing fracture pressure obtaining method and device provided by the embodiments of the present invention obtain formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters, and formation mechanical parameters, and the effects of wellbore fluid pressure and ground stress Next, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established. According to the established casing stress field distribution model, cement sheath stress field distribution model and formation stress field distribution model, the wellbore stress field model under the condition of casing perforation completion is established; then according to the wellbore stress field model, hydraulic pressure Based on the fracture theory and fracture criterion, the fracture pressure of hydraulic fracturing is obtained. Compared with the existing methods for obtaining the fracture pressure of hydraulic fracturing, the method for obtaining the fracture pressure of hydraulic fracturing provided by the embodiment of the present invention improves that during the fracturing process, the fracturing fluid directly enters tiny fractures, which is not conducive to the fracture pressure of hydraulic fracturing. problem of accurate calculation.

In the embodiments provided in this application, it should be understood that the disclosed device may also be implemented in other ways. The device embodiments described above are illustrative only.

In addition, each functional module in the embodiment of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes. . It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. any such actual relationship or order exists between them. Furthermore, the terms "comprises", "comprises" or any other variation thereof are intended to cover a non-exclusive inclusion such that a process, article or apparatus comprising a set of elements includes not only those elements but also other elements not expressly listed. elements, or also elements inherent in such processes, articles or equipment. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, article or device comprising said element.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (10)

1. A hydraulic fracturing fracture pressure obtaining method is characterized in that, the method comprises: Obtain formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters and formation mechanical parameters; Under the action of wellbore fluid pressure and ground stress, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established; According to the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model, the wellbore stress field model under the condition of casing perforation completion is established; According to the wellbore stress field model, hydraulic fracturing theory and fracture criterion, the hydraulic fracturing fracture pressure is obtained. 2. The method according to claim 1, wherein said obtaining formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters and formation mechanical parameters comprises: Obtain formation stress parameters and pore fluid pressure values according to the data obtained after well logging; Obtain casing mechanical parameters and cement sheath mechanical parameters according to the data obtained after cementing; Formation mechanical parameters are obtained from data obtained after well logging or through experimental testing of rocks. 3. The method according to claim 1, characterized in that, under the action of the wellbore fluid pressure and the ground stress, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established, include: Under the single action of wellbore fluid pressure, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established; Under the single action of horizontal ground stress, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established; Under the single action of vertical in-situ stress, the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model are respectively established. 4. method according to claim 3, it is characterized in that, described under the independent action of horizontal ground stress, set up casing stress field distribution model, cement sheath stress field distribution model and stratum stress field distribution model respectively, comprising: Solve the far-away stress field on the horizontal plane under the boundary condition A; among them, the boundary condition A is Solve the far-away stress field on the horizontal plane under the boundary condition B; among them, the boundary condition B is Among them, σ _r is the radial stress, σ is the average in-situ stress, τ _rθ is the tangential stress, θ is the borehole circumferential angle, and S is the deviated in-situ stress; Obtain the stress expression corresponding to the formation; Obtain the stress expression corresponding to the cement sheath; Obtain the stress expression corresponding to the casing; The unknown variables in the stress expression corresponding to the formation, the stress expression corresponding to the cement sheath and the stress expression corresponding to the casing are solved. 5. The method according to claim 1, wherein the fracture criterion is: σ ₁ -αP _p >S _t , wherein σ ₁ is the maximum principal stress, _st is the rock tensile strength, and α is Biot coefficient, P _p is the pore fluid pressure. 6. A hydraulic fracturing pressure obtaining device, characterized in that the device comprises: The parameter acquisition module is used to obtain formation stress parameters, pore fluid pressure values, casing mechanical parameters, cement sheath mechanical parameters and formation mechanical parameters; The first model building module is used to respectively establish a casing stress field distribution model, a cement sheath stress field distribution model, and a formation stress field distribution model under the action of wellbore fluid pressure and ground stress; The second model building module is used to establish a stress field model around the well under the casing perforation completion condition according to the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model; The hydraulic fracturing fracture pressure acquisition module is used to obtain the hydraulic fracturing fracture pressure according to the stress field model around the well, the hydraulic fracturing theory and the fracture criterion. 7. The device according to claim 6, wherein the parameter acquisition module comprises: The first parameter acquisition sub-module is used to obtain formation geostress parameters and pore fluid pressure values according to data obtained after well logging; The second parameter acquisition sub-module is used to obtain casing mechanical parameters and cement sheath mechanical parameters according to the data obtained after cementing; The third parameter acquisition sub-module is used to obtain formation mechanical parameters according to data obtained after well logging or through experimental tests on rocks. 8. The device according to claim 6, wherein the first model building module comprises: The wellbore fluid pressure model establishment sub-module is used to respectively establish the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model under the sole action of the wellbore fluid pressure; The horizontal ground stress model establishment sub-module is used to respectively establish the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model under the single action of the horizontal ground stress; The sub-module for establishing the vertical ground stress model is used to establish the casing stress field distribution model, the cement sheath stress field distribution model and the formation stress field distribution model respectively under the vertical ground stress alone. 9. The device according to claim 8, characterized in that, said horizontal ground stress model establishment submodule comprises: The first solving sub-module is used to solve the horizontal plane remote stress field under the boundary condition A; among them, the boundary condition A is The second solving sub-module is used to solve the horizontal plane remote stress field under the boundary condition B; where, the boundary condition B is Among them, σ _r is the radial stress, σ is the average in-situ stress, τ _rθ is the tangential stress, θ is the borehole circumferential angle, and S is the deviated in-situ stress; The formation expression sub-module is used to obtain the stress expression corresponding to the formation; The cement sheath expression sub-module is used to obtain the corresponding stress expression of the cement sheath; The casing expression sub-module is used to obtain the stress expression corresponding to the casing; The unknown variable solving sub-module is used to solve the unknown variables in the stress expression corresponding to the formation, the stress expression corresponding to the cement sheath, and the stress expression corresponding to the casing. 10. The device according to claim 6, wherein the fracture criterion is: σ ₁ -αP _p >S _t , wherein σ ₁ is the maximum principal stress, _st is the rock tensile strength, and α is Biot coefficient, P _p is the pore fluid pressure.