CN116243386A - A method and system for constructing acoustic time-difference curves of drilling rock formations - Google Patents

Abstract

The present invention specifically relates to a method for constructing the acoustic wave time difference curve of the drilling rock formation, comprising: constructing the relational expression between the sound wave propagation velocity of the rock formation, the depth of the rock formation, and the resistivity of the three sides of the rock formation; According to the relationship between the rock formation acoustic time difference curve and the rock formation acoustic logging data of the drilling hole, the rock formation acoustic time difference curve between the rock formation acoustic time difference and the depth of the rock formation and the three lateral resistivities of the rock formation is regressed; from the missing rock formation acoustic wave The parameters necessary for calculating the rock formation acoustic time difference are extracted from the rock formation acoustic logging data of the time difference curve drilling and substituted into the rock formation acoustic time difference regression curve, and the rock formation acoustic time difference parameters of the missing rock formation acoustic time difference curve drilling are calculated. The method for constructing the sonic time difference curve of the rock strata in the present invention can obtain the sonic time difference parameters of the rock stratum in the hole without the sonic time difference curve of the rock stratum, so as to obtain the real density of the rock strata in the well.

Description

A method and system for constructing acoustic time difference curve of drilling rock formation

Technical Field

The invention relates to the technical field of in-situ leachable sandstone type uranium ore exploration, and in particular to a method and system for constructing a borehole rock stratum acoustic wave time difference curve.

Background Art

In the field comprehensive logging work of searching for in-situ leachable sandstone-type uranium deposits, the sonic probe often fails due to poor working conditions and rough and bumpy roads. If the failure of the sonic probe cannot be eliminated at the logging site, it is necessary to give up measuring the rock formation sonic time difference parameters of the borehole. The rock formation sonic time difference parameters can effectively distinguish sandstone from mudstone in the sandstone-mudstone section.

Since the propagation velocity of rock formation sound waves is closely related to the density of rock formation, the rock formation sound wave time difference is an effective logging parameter for detecting the real density of rock formation in the well. Because according to scientific research, within the burial depth range of less than 1700 meters, that is, the effective pressure is less than 20MPa, the propagation velocity of rock formation sound waves increases with the increase of the effective pressure of the overlying stratum, and the density of rock formation increases with the increase of the propagation velocity of rock formation sound waves.

The exploration drilling depth for searching for in-situ leachable sandstone-type uranium deposits is just less than 1,700 meters, that is, within the burial depth range where the effective pressure is less than 20 MPa. The close relationship between the acoustic wave propagation velocity of the rock formation and its density means that during the exploration of in-situ leachable sandstone-type uranium deposits, the change in rock formation density can be obtained through the change in the acoustic wave propagation velocity of the rock formation.

In the process of exploration of in-situ leachable sandstone-type uranium deposits, if the field logging accidentally causes the loss of the rock formation acoustic wave time difference parameters, the γ-γ method is generally used to measure the rock formation density. However, due to the pressure relief effect of the borehole and the shallow radial detection depth, the density measured by the γ-γ method is no longer the true density of the rock formation underground, but the density of the rock formation after pressure relief. Therefore, in the process of exploration of in-situ leachable sandstone-type uranium deposits, the loss of the rock formation acoustic wave time difference parameters caused by the field logging accident will lead to the inability to obtain the true density of the rock formation underground.

Summary of the invention

Based on this, the present invention aims at the problem that in the exploration process of in-situ leachable sandstone-type uranium deposits, the rock formation acoustic time difference parameters are lost due to accidental field logging, resulting in the inability to obtain the true density of the rock formation underground. A method and system for constructing a borehole rock formation acoustic time difference curve is provided. The method and system regress the rock formation acoustic time difference regression curve of the borehole where the rock formation acoustic time difference curve is missing based on the rock formation acoustic logging data of the borehole where the rock formation acoustic time difference curve is missing, thereby obtaining the rock formation acoustic time difference parameters of the borehole where the rock formation acoustic time difference curve is missing, so as to obtain the true density of the rock formation underground.

In order to achieve the above object, the present invention provides the following technical solutions:

A method for constructing a borehole rock formation acoustic wave time difference curve comprises the following steps:

Step 1, constructing a relationship between the propagation velocity of rock sound waves and the rock depth and the three-dimensional resistivity of the rock;

Step 2, substituting the relationship between the rock formation acoustic wave propagation velocity and the rock formation acoustic wave time difference into the relationship in step 1, and obtaining the relationship between the rock formation acoustic wave time difference and the rock formation depth and the three-dimensional resistivity of the rock formation;

Step 3, regressing the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-dimensional resistivity of the formation according to the formation acoustic wave time difference curve of the formation acoustic wave logging data of the well borehole;

Step 4: Use the formation acoustic time difference regression curve of step 3 as the formation acoustic time difference regression curve of the borehole where the formation acoustic time difference curve is missing, extract the parameters necessary for calculating the formation acoustic time difference from the formation acoustic logging data of the borehole where the formation acoustic time difference curve is missing, and substitute them into the formation acoustic time difference regression curve to calculate the formation acoustic time difference parameters of the borehole where the formation acoustic time difference curve is missing.

Furthermore, in step 1, the relationship between the rock formation acoustic wave propagation velocity and the rock formation depth and the three-dimensional resistivity of the rock formation is:

Where V is the acoustic wave propagation velocity of the rock formation, in m/s; H is the depth of the rock formation, in m; _Rt is the three-dimensional resistivity of the rock formation, in Ω·m; M is the regional formation factor; A and N are unknown parameters.

Furthermore, according to rock acoustic theory, the relationship between the propagation velocity of rock formation sound waves and the rock formation sound wave time difference is as follows:

Substituting equation (3) into the equation in step 1, we get the following equation:

The statistical relationship between the acoustic time difference of the rock formation and the rock formation depth and the three-dimensional resistivity of the rock formation is obtained by sorting out the relationship (5):

Wherein, V is the propagation velocity of rock acoustic waves, in m/s; △t is the rock acoustic wave time difference, in μs/m; H is the rock depth, in m; _Rt is the three-dimensional resistivity of the rock, in Ω·m; M is the regional formation factor; A and N are parameters to be determined.

Further, step 3, based on the formation acoustic wave time difference curve, the formation acoustic wave logging data of the well borehole is regressed to obtain a formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-dimensional resistivity of the formation, including the following steps:

Step 3.1, take the logarithm of both sides of the relationship (6), and transpose the terms to obtain the following relationship:

Step 3.2: For the convenience of calculation, replace the variables in equation (7) and assume:

Step 3.3: Substitute equation (8) into equation (7) to obtain:

y＝b ₀ +b ₁ x ₁ +b ₂ x ₂ (9)

Step 3.4: Arrange the rock formation acoustic wave time difference curve according to the relationship (9) to improve the relationship between the acoustic wave time difference parameters of each rock formation in the borehole and the depth parameters of each rock formation and the three-dimensional resistivity parameters of each rock formation as follows:

y ₁ =b ₀ +b ₁ x ₁₁ +b ₂ x ₁₂

y ₂ =b ₀ +b ₁ x ₂₁ +b ₂ x ₂₂

y ₃ =b ₀ +b ₁ x ₃₁ +b ₂ x ₃₂

………………………………

y _i ＝b ₀ +b ₁ x _i1 +b ₂ x _i2

Step 3.5, using the formation acoustic wave time difference curve to improve the formation acoustic wave logging data of the borehole to solve b ₀ , b ₁ and b ₂ ;

Step 3.6, substitute the solved _b0 , _b1 and _b2 into the relational expression (8) to solve A, N and M; substitute A, N and M into the relational expression (6) to complete the regression of the rock formation acoustic wave time difference curve between the rock formation depth and the rock formation three-way resistivity;

The rock formation acoustic wave time difference curve sound borehole is a rock formation acoustic wave time difference curve sound borehole which is closest to the missing rock formation acoustic wave time difference curve borehole in the same working area and the same formation system.

Further, the formation acoustic logging data of the well-established borehole of the formation acoustic time difference curve is composed of n formation acoustic logging data, and the i-th formation acoustic logging data includes the following parameters: formation acoustic time difference (△t) _i , formation depth H _i and formation three-dimensional resistivity (R _t ) _i ;

x ₁ ={x ₁₁ , x ₂₁ , x ₃₁ .. x _i1 }, x _i1 is calculated based on the rock formation depth _Hi of the rock formation acoustic wave time difference curve;

x ₂ ={x ₁₂ , x ₂₂ , x ₃₂ .. x _i2 }, x _i2 is calculated based on the three-dimensional resistivity depth (R _t ) _i of the well-developed borehole rock formation based on the rock formation acoustic wave time difference curve;

y＝{y ₁ , y ₂ , y ₃ .. y _i }, y _i is calculated based on the formation acoustic wave time difference curve and the sound borehole formation acoustic wave time difference (△t) _i .

Furthermore, step 3.5, solving b ₀ , b ₁ and b ₂ by using the formation acoustic logging data of the borehole through the formation acoustic time difference curve, comprises the following steps:

Step 3.5.1, construct the linear equation system as follows:

L ₁₁ b ₁ +L ₁₂ b ₂ =L _1y (10)

L ₂₁ b ₁ +L ₂₂ b ₂ =L _2y (11)

in,

_L21 ＝ _L12 (14)

Step 3.5.2, establish the following matrix to solve the linear equations:

Solve for b ₀ , b ₁ , and b ₂ .

Furthermore, the regression quality of the rock formation acoustic wave time difference regression curve between the rock formation acoustic wave time difference and the rock formation depth and the rock formation three-lateral resistivity is evaluated by the fitting degree. The calculation formula of the fitting degree is as follows:

为岩层声波时差回归值；R²为拟和度。Where Ass is the sum of squares of acoustic time difference observations of each rock layer; Bss is the sum of squares of the difference between the acoustic time difference observations of each rock layer and the regression value; _yi is the acoustic time difference observation value of the rock layer;

is the regression value of the rock formation acoustic wave time difference; ^R2 is the degree of fit.

Further, step 3.5.2, establish matrix (5) to solve the linear equations (9) and (10) to obtain b ₀ , b ₁ and b ₂ , including the following steps:

In Excel, follow these steps:

The parameters of the formation acoustic logging data of the well-developed borehole of the formation acoustic time difference curve are stored in Excel workbooks by columns;

Calculate the logarithm of the acoustic time difference (△t) _i of each rock layer and the logarithm of the depth H _i of each rock layer by solving the logarithmic function "log()" respectively, and store the calculated log(△t) _i and logH _i in the Excel workbook by column respectively;

和

分别存储在所述Excel工作簿中；L ₁₁ , L ₁₂ , L ₂₁ , L ₂₂ , L _1y and L _2y are calculated respectively by equations (12)-(17), and the calculated L ₁₁ , L 12 , L ₂₁ , L ₂₂ , L _1y and L _2y are _converted into the matrix

and

are stored in the Excel workbook respectively;

的逆矩阵，通过求解矩阵积函数“MMULT()求解出矩阵

的逆矩阵和矩阵

的乘积，求解出b₁和b₂并存储在所述Excel工作簿中；Solve the matrix by solving the inverse matrix function "MINVERSE()"

The inverse matrix of the matrix is solved by solving the matrix product function "MMULT()

The inverse matrix and matrix

The product of is solved for _b1 and _b2 and stored in the Excel workbook;

According to the relation (18), _b0 is calculated and stored in the Excel workbook.

Further, in step 3.6, in Excel software, the solved _b0 , _b1 and _b2 are substituted into the relational equation (8) to solve A, N and M; A, N and M are substituted into the relational equation (6) to complete the regression of the rock formation acoustic wave time difference curve between the rock formation depth and the rock formation three-way resistivity.

Further, in the Excel software, the calculated b ₀ , b ₁ and b ₂ are substituted into the relational expression (9), and the regression value of the logarithm of the acoustic time difference of the rock formation is solved and stored in the Excel workbook by column;

The rock formation acoustic wave time difference regression value is solved by solving the antilogarithmic function "Power()" and stored in the Excel workbook by column;

According to equations (19)-(20), the square of the acoustic wave observation value of each rock layer Ass and the sum of the squares of the difference between the acoustic wave time difference observation value and the regression value of each rock layer Bss are calculated;

The goodness of fit R ² of the rock formation acoustic wave time difference regression curve is calculated according to equation (21).

Furthermore, in step 4, the rock formation acoustic logging data of the borehole where the rock formation acoustic time difference curve is missing includes the following parameters: rock formation depth H and rock formation three-dimensional resistivity R _t .

The present invention also provides a drilling rock formation acoustic wave time difference curve construction system, comprising:

A data acquisition module is used to acquire the formation acoustic logging data of the borehole with a sound formation acoustic time difference curve and the formation acoustic logging data of the borehole with a missing formation acoustic time difference curve, and send the formation acoustic logging data of the borehole with a sound formation acoustic time difference curve to the curve regression module, and send the formation acoustic logging data of the borehole with a missing formation acoustic time difference curve to the parameter calculation module;

The curve regression module is used to receive the formation acoustic wave time difference curve sent by the data acquisition module to improve the formation acoustic wave logging data of the borehole, and regress the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation according to the relationship between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation, and send it to the parameter calculation module;

The parameter calculation module is used to receive the rock formation acoustic logging data of the borehole with missing rock formation acoustic time difference curve sent by the data acquisition module and the rock formation acoustic time difference regression curve sent by the curve regression module, extract the parameters necessary for calculating the rock formation acoustic time difference from the rock formation acoustic logging data of the borehole with missing rock formation acoustic time difference curve, substitute them into the rock formation acoustic time difference regression curve, and calculate the rock formation acoustic time difference parameters of the borehole with missing rock formation acoustic time difference curve.

Furthermore, the relationship between the acoustic time difference of the rock formation and the rock formation depth and the three-dimensional resistivity of the rock formation is:

Wherein, V is the propagation velocity of rock acoustic waves, in m/s; △t is the rock acoustic wave time difference, in μs/m; H is the rock depth, in m; _Rt is the three-dimensional resistivity of the rock, in Ω·m; M is the regional formation factor; A and N are parameters to be determined.

Further, the curve regression module receives the formation acoustic wave time difference curve sent by the data acquisition module to improve the formation acoustic wave logging data of the borehole, and regresses the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation according to the relationship between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation, including the following steps:

Taking the logarithm of both sides of the relationship (6) and transposing the terms, we get the following relationship:

Substitute the variables in equation (7) and assume:

Substituting equation (8) into equation (7), we obtain:

y＝b ₀ +b ₁ x ₁ +b ₂ x ₂ (9)

According to the relation (9), the relation between the acoustic wave time difference curve of each rock layer in the wellbore and the depth parameters of each rock layer and the three-dimensional resistivity parameters of each rock layer is as follows:

y ₁ =b ₀ +b ₁ x ₁₁ +b ₂ x ₁₂

y ₂ =b ₀ +b ₁ x ₂₁ +b ₂ x ₂₂

y ₃ =b ₀ +b ₁ x ₃₁ +b ₂ x ₃₂

………………………………

y _i ＝b ₀ +b ₁ x _i1 +b ₂ x _i2

Solve b ₀ , b ₁ and b ₂ by using the formation acoustic logging data of the wellbore through the formation acoustic time difference curve;

Substitute the solved _b0 , _b1 and _b2 into equation (8) to solve A, N and M; Substitute A, N and M into equation (6) to complete the regression of the rock formation acoustic wave time difference curve between the rock formation depth and the rock formation three-way resistivity;

The rock formation acoustic wave time difference curve sound borehole is a rock formation acoustic wave time difference curve sound borehole which is closest to the missing rock formation acoustic wave time difference curve borehole in the same working area and the same formation system.

Further, the formation acoustic logging data of the well-established borehole of the formation acoustic time difference curve is composed of n formation acoustic logging data, and the i-th formation acoustic logging data includes the following parameters: formation acoustic time difference (△t) _i , formation depth H _i and formation three-dimensional resistivity (R _t ) _i ;

x ₁ ={x ₁₁ , x ₂₁ , x ₃₁ .. x _i1 }, where x _i1 is calculated by the curve regression module based on the formation acoustic wave time difference curve to improve the borehole formation depth _Hi ;

x ₂ ={x ₁₂ , x ₂₂ , x ₃₂ .. x _i2 }, where x _i2 is calculated by the curve regression module based on the three-dimensional resistivity depth (R _t ) _i of the well-established borehole rock formation based on the rock formation acoustic wave time difference curve;

y＝{y ₁ , y ₂ , y ₃ .. y _i }, y _i is calculated by the curve regression module according to the formation acoustic wave time difference curve of the well-established borehole rock formation acoustic wave time difference (△t) _i .

Furthermore, the curve regression module solves b ₀ , b ₁ and b ₂ by using the formation acoustic logging data of the wellbore through the formation acoustic time difference curve, including the following steps:

The linear equations are constructed as follows:

L ₁₁ b ₁ +L ₁₂ b ₂ =L _1y (10)

L ₂₁ b ₁ +L ₂₂ b ₂ =L _2y (11)

in,

_L21 ＝ _L12 (14)

The following matrix is established to solve the linear equations:

Solve for b ₀ , b ₁ , and b ₂ .

Furthermore, the curve regression module evaluates the regression quality of the rock formation acoustic wave time difference regression curve between the rock formation acoustic wave time difference and the rock formation depth and the rock formation three-lateral resistivity through the fitting degree. The calculation formula of the fitting degree is as follows:

为岩层声波时差回归值；R²为拟和度。Where Ass is the sum of squares of acoustic time difference observations of each rock layer; Bss is the sum of squares of the difference between the acoustic time difference observations of each rock layer and the regression value; _yi is the acoustic time difference observation value of the rock layer;

is the regression value of the rock formation acoustic wave time difference; ^R2 is the degree of fit.

Furthermore, the curve regression module establishes the matrix (5) to solve the linear equations (9) and (10) to obtain b ₀ , b ₁ and b ₂ , including the following steps:

Call Excel software and perform the following steps:

The parameters of the formation acoustic logging data of the well-developed borehole of the formation acoustic time difference curve are stored in Excel workbooks by columns;

Calculate the logarithm of the acoustic time difference (△t) _i of each rock layer and the logarithm of the depth H _i of each rock layer by solving the logarithmic function "log()" respectively, and store the calculated log(△t) _i and logH _i in the Excel workbook by column respectively;

和

分别存储在所述Excel工作簿中；L ₁₁ , L ₁₂ , L ₂₁ , L ₂₂ , L _1y and L _2y are calculated respectively by equations (12)-(17), and the calculated L ₁₁ , L 12 , L ₂₁ , L ₂₂ , L _1y and L _2y are _converted into the matrix

and

are stored in the Excel workbook respectively;

的逆矩阵，通过求解矩阵积函数“MMULT()求解出矩阵

的逆矩阵和矩阵

的乘积，求解出b₁和b₂并存储在所述Excel工作簿中；Solve the matrix by solving the inverse matrix function "MINVERSE()"

The inverse matrix of the matrix is solved by solving the matrix product function "MMULT()

The inverse matrix and matrix

The product of is solved for _b1 and _b2 and stored in the Excel workbook;

According to the relation (18), _b0 is calculated and stored in the Excel workbook.

Furthermore, the curve regression module calls Excel software, substitutes the solved _b0 , _b1 and _b2 into the relationship (8), and solves A, N and M; substitutes A, N and M into the relationship (6) to complete the rock formation acoustic wave time difference curve regression between the rock formation depth and the rock formation three-way resistivity.

Furthermore, the curve regression module calls Excel software, substitutes the calculated b ₀ , b ₁ and b ₂ into equation (9), solves the regression value of the logarithm of the rock formation acoustic wave time difference and stores it in the Excel workbook by column;

The rock formation acoustic wave time difference regression value is solved by solving the antilogarithmic function "Power()" and stored in the Excel workbook by column;

According to equations (19)-(20), the square of the acoustic wave observation value of each rock layer Ass and the sum of the squares of the difference between the acoustic wave time difference observation value and the regression value of each rock layer Bss are calculated;

The goodness of fit R ² of the rock formation acoustic wave time difference regression curve is calculated according to equation (21).

Beneficial technical effects of the present invention:

The method and system for constructing a borehole rock formation acoustic wave time difference curve of the present invention regresses the rock formation acoustic wave time difference regression curve of the borehole with missing rock formation acoustic wave time difference curve based on the rock formation acoustic wave time difference curve of the complete borehole rock formation acoustic wave logging data; the rock formation acoustic wave time difference regression curve is more sensitive to the effective pressure of the overlying stratum than the measured rock formation acoustic wave time difference curve, and the measured rock formation density calculated thereby is more accurate; the rock formation acoustic wave time difference regression curve can more accurately reflect the physical properties of the rock formation than the measured rock formation acoustic wave time difference curve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a method for constructing a borehole rock formation acoustic time difference curve according to the present invention;

FIG2 is a schematic diagram of the structure of a drilling rock formation acoustic wave time difference curve construction system of the present invention;

FIG3 is a comparison diagram of the rock formation acoustic wave time difference regression curve and the measured rock formation acoustic wave time difference curve.

DETAILED DESCRIPTION

The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Referring to FIG. 1 , the present invention provides a method for constructing a borehole rock formation acoustic wave time difference curve, comprising the following steps:

Step 1, constructing a relationship between the propagation velocity of rock sound waves and the rock depth and the three-dimensional resistivity of the rock;

Step 2, substituting the relationship between the rock formation acoustic wave propagation velocity and the rock formation acoustic wave time difference into the relationship in step 1, and obtaining the relationship between the rock formation acoustic wave time difference and the rock formation depth and the three-dimensional resistivity of the rock formation;

Step 3, regressing the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-dimensional resistivity of the formation according to the formation acoustic wave time difference curve of the formation acoustic wave logging data of the well borehole;

Step 4: Use the formation acoustic time difference regression curve of step 3 as the formation acoustic time difference regression curve of the borehole where the formation acoustic time difference curve is missing, extract the parameters necessary for calculating the formation acoustic time difference from the formation acoustic logging data of the borehole where the formation acoustic time difference curve is missing, and substitute them into the formation acoustic time difference regression curve to calculate the formation acoustic time difference parameters of the borehole where the formation acoustic time difference curve is missing.

Furthermore, in step 1, the relationship between the rock formation acoustic wave propagation velocity and the rock formation depth and the three-dimensional resistivity of the rock formation is:

V＝A*H ^N *M ^R t(4)

Where V is the acoustic wave propagation velocity of the rock formation, in m/s; H is the depth of the rock formation, in m; _Rt is the three-dimensional resistivity of the rock formation, in Ω·m; M is the regional formation factor; A and N are unknown parameters.

In the late 1940s and early 1950s, Foster studied logging data of more than one million feet, compared the three-dimensional resistivity of the rock formation with the propagation velocity of rock sound waves, and obtained the relationship between the propagation velocity of rock sound waves and the depth of the rock formation and the three-dimensional resistivity of the rock formation:

V＝K*H*C*d*Rt(1)

Where V is the acoustic wave propagation velocity of the rock formation, in m/s; H is the depth of the rock formation, in m; _Rt is the three-dimensional resistivity of the rock formation, in Ω·m; K, C and d are all parameters, which are selected according to different regions and are dimensionless.

Through a large number of acoustic experiments, the petroleum system has studied the relationship between the propagation velocity of rock sound waves and the depth of the rock layer and the effective pressure of the underlying strata:

V＝a*(PH) ^c (2)

Wherein, V is the propagation velocity of sound waves in the rock formation, in m/s; P is the effective pressure of the underlying stratum in the rock formation, in KPa/h; H is the depth of the rock formation, in m; a and c are parameters.

Based on the relationship between the propagation velocity of rock sound waves and the three-dimensional resistivity of rock formations, the depth of rock formations and the effective pressure of the underlying strata of rock formations studied by previous researchers, the inventor innovatively proposed a relationship between the propagation velocity of rock sound waves and the depth of rock formations and the three-dimensional resistivity of rock formations:

Where V is the acoustic wave propagation velocity of the rock formation, in m/s; H is the depth of the rock formation, in m; _Rt is the three-dimensional resistivity of the rock formation, in Ω·m; M is the regional formation factor; A and N are unknown parameters.

Furthermore, according to rock acoustic theory, the relationship between the propagation velocity of rock formation sound waves and the rock formation sound wave time difference is as follows:

Substituting equation (3) into the equation in step 1, we get the following equation:

The statistical relationship between the acoustic time difference of the rock formation and the rock formation depth and the three-dimensional resistivity of the rock formation is obtained by sorting out the relationship (5):

Wherein, V is the propagation velocity of rock acoustic waves, in m/s; △t is the rock acoustic wave time difference, in μs/m; H is the rock depth, in m; _Rt is the three-dimensional resistivity of the rock, in Ω·m; M is the regional formation factor; A and N are parameters to be determined.

After a large number of rock formation acoustic time difference curves and sound drilling practice verification, the rock formation acoustic time difference parameters obtained by regression of the relational equation (6) proposed in the present invention and the actual measured rock formation acoustic time difference parameters have a fitting degree of more than 90%, and satisfactory results have been obtained. The practice verification results prove that the relational equation (6) proposed in the present invention is correct and feasible.

Further, step 3, based on the formation acoustic wave time difference curve, the formation acoustic wave logging data of the well borehole is regressed to obtain a formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-dimensional resistivity of the formation, including the following steps:

Step 3.1, take the logarithm of both sides of the relationship (6), and transpose the terms to obtain the following relationship:

Step 3.2: For the convenience of calculation, replace the variables in equation (7) and assume:

Step 3.3: Substitute equation (8) into equation (7) to obtain:

y＝b ₀ +b ₁ x ₁ +b ₂ x ₂ (9)

Step 3.4: Arrange the rock formation acoustic wave time difference curve according to the relationship (9) to improve the relationship between the acoustic wave time difference parameters of each rock formation in the borehole and the depth parameters of each rock formation and the three-dimensional resistivity parameters of each rock formation as follows:

y ₁ =b ₀ +b ₁ x ₁₁ +b ₂ x ₁₂

y ₂ =b ₀ +b ₁ x ₂₁ +b ₂ x ₂₂

y ₃ =b ₀ +b ₁ x ₃₁ +b ₂ x ₃₂

………………………………

y _i ＝b ₀ +b ₁ x _i1 +b ₂ x _i2

Step 3.5, using the formation acoustic wave time difference curve to improve the formation acoustic wave logging data of the borehole to solve b ₀ , b ₁ and b ₂ ;

Step 3.6, substitute the solved _b0 , _b1 and _b2 into the relational expression (8) to solve A, N and M; substitute A, N and M into the relational expression (6) to complete the regression of the rock formation acoustic wave time difference curve between the rock formation depth and the rock formation three-way resistivity;

The rock formation acoustic wave time difference curve sound borehole is a rock formation acoustic wave time difference curve sound borehole which is closest to the missing rock formation acoustic wave time difference curve borehole in the same working area and the same formation system.

Further, the formation acoustic logging data of the well-established borehole of the formation acoustic time difference curve is composed of n formation acoustic logging data, and the i-th formation acoustic logging data includes the following parameters: formation acoustic time difference (△t) _i , formation depth H _i and formation three-dimensional resistivity (R _t ) _i ;

x ₁ ={x ₁₁ , x ₂₁ , x ₃₁ .. x _i1 }, x _i1 is calculated based on the rock formation depth _Hi of the rock formation acoustic wave time difference curve;

x ₂ ={x ₁₂ , x ₂₂ , x ₃₂ .. x _i2 }, x _i2 is calculated based on the three-dimensional resistivity depth (R _t ) _i of the well-developed borehole rock formation based on the rock formation acoustic wave time difference curve;

y＝{y ₁ , y ₂ , y ₃ .. y _i }, y _i is calculated based on the formation acoustic wave time difference curve and the sound borehole formation acoustic wave time difference (△t) _i .

Furthermore, step 3.5, solving b ₀ , b ₁ and b ₂ by using the formation acoustic logging data of the borehole through the formation acoustic time difference curve, comprises the following steps:

Step 3.5.1, construct the linear equation system as follows:

L ₁₁ b ₁ +L ₁₂ b ₂ =L _1y (10)

L ₂₁ b ₁ +L ₂₂ b ₂ =L _2y (11)

in,

_L21 ＝ _L12 (14)

Step 3.5.2, establish the following matrix to solve the linear equations:

Solve for b ₀ , b ₁ , and b ₂ .

Furthermore, the regression quality of the rock formation acoustic wave time difference regression curve between the rock formation acoustic wave time difference and the rock formation depth and the rock formation three-lateral resistivity is evaluated by the fitting degree. The calculation formula of the fitting degree is as follows:

为岩层声波时差回归值；R²为拟和度。Where Ass is the sum of squares of acoustic time difference observations of each rock layer; Bss is the sum of squares of the difference between the acoustic time difference observations of each rock layer and the regression value; _yi is the acoustic time difference observation value of the rock layer;

is the regression value of the rock formation acoustic wave time difference; ^R2 is the degree of fit.

The degree of fit ^R2 refers to the degree of fit of the regression curve to the observed value. The maximum value of ^R2 is 1. The closer ^R2 is to 1, the better the regression curve fits the observed value, the higher the degree of explanation of the independent variable to the dependent variable, the higher the percentage of changes caused by the independent variable in the total change, and the denser the observation points are near the regression curve. Conversely, the smaller the value of ^R2 , the worse the regression curve fits the observed value, and the fewer the observation points are near the regression curve.

Further, step 3.5.2, establish matrix (5) to solve the linear equations (9) and (10) to obtain b ₀ , b ₁ and b ₂ , including the following steps:

In Excel, follow these steps:

The parameters of the formation acoustic logging data of the well-developed borehole of the formation acoustic time difference curve are stored in Excel workbooks by columns;

Calculate the logarithm of the acoustic time difference (△t) _i of each rock layer and the logarithm of the depth H _i of each rock layer by solving the logarithmic function "log()" respectively, and store the calculated log(△t) _i and logH _i in the Excel workbook by column respectively;

和

分别存储在所述Excel工作簿中；L ₁₁ , L ₁₂ , L ₂₁ , L ₂₂ , L _1y and L _2y are calculated respectively by equations (12)-(17), and the calculated L ₁₁ , L 12 , L ₂₁ , L ₂₂ , L _1y and L _2y are _converted into the matrix

and

are stored in the Excel workbook respectively;

的逆矩阵，通过求解矩阵积函数“MMULT()求解出矩阵

的逆矩阵和矩阵

的乘积，求解出b₁和b₂并存储在所述Excel工作簿中；Solve the matrix by solving the inverse matrix function "MINVERSE()"

The inverse matrix of the matrix is solved by solving the matrix product function "MMULT()

The inverse matrix and matrix

The product of is solved for _b1 and _b2 and stored in the Excel workbook;

According to the relation (18), _b0 is calculated and stored in the Excel workbook.

Further, in step 3.6, in Excel software, the solved _b0 , _b1 and _b2 are substituted into the relational equation (8) to solve A, N and M; A, N and M are substituted into the relational equation (6) to complete the regression of the rock formation acoustic wave time difference curve between the rock formation depth and the rock formation three-way resistivity.

Further, in the Excel software, the calculated b ₀ , b ₁ and b ₂ are substituted into the relational expression (9), and the regression value of the logarithm of the acoustic time difference of the rock formation is solved and stored in the Excel workbook by column;

The rock formation acoustic wave time difference regression value is solved by solving the antilogarithmic function "Power()" and stored in the Excel workbook by column;

According to equations (19)-(20), the square of the acoustic wave observation value of each rock layer Ass and the sum of the squares of the difference between the acoustic wave time difference observation value and the regression value of each rock layer Bss are calculated;

The goodness of fit R ² of the rock formation acoustic wave time difference regression curve is calculated according to equation (21).

Furthermore, in step 4, the rock formation acoustic logging data of the borehole where the rock formation acoustic time difference curve is missing includes the following parameters: rock formation depth H and rock formation three-dimensional resistivity R _t .

Referring to FIG. 2 , the present invention further provides a drilling rock formation acoustic wave time difference curve construction system, comprising:

A data acquisition module is used to acquire the formation acoustic logging data of the borehole with a sound formation acoustic time difference curve and the formation acoustic logging data of the borehole with a missing formation acoustic time difference curve, and send the formation acoustic logging data of the borehole with a sound formation acoustic time difference curve to the curve regression module, and send the formation acoustic logging data of the borehole with a missing formation acoustic time difference curve to the parameter calculation module;

The curve regression module is used to receive the formation acoustic wave time difference curve sent by the data acquisition module to improve the formation acoustic wave logging data of the borehole, and regress the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation according to the relationship between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation, and send it to the parameter calculation module;

The parameter calculation module is used to receive the rock formation acoustic logging data of the borehole with missing rock formation acoustic time difference curve sent by the data acquisition module and the rock formation acoustic time difference regression curve sent by the curve regression module, extract the parameters necessary for calculating the rock formation acoustic time difference from the rock formation acoustic logging data of the borehole with missing rock formation acoustic time difference curve, substitute them into the rock formation acoustic time difference regression curve, and calculate the rock formation acoustic time difference parameters of the borehole with missing rock formation acoustic time difference curve.

Furthermore, the relationship between the acoustic time difference of the rock formation and the rock formation depth and the three-dimensional resistivity of the rock formation is:

Wherein, V is the propagation velocity of rock acoustic waves, in m/s; △t is the rock acoustic wave time difference, in μs/m; H is the rock depth, in m; _Rt is the three-dimensional resistivity of the rock, in Ω·m; M is the regional formation factor; A and N are parameters to be determined.

Further, the curve regression module receives the formation acoustic wave time difference curve sent by the data acquisition module to improve the formation acoustic wave logging data of the borehole, and regresses the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation according to the relationship between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation, including the following steps:

Taking the logarithm of both sides of the relationship (6) and transposing the terms, we get the following relationship:

Substitute the variables in equation (7) and assume:

Substituting equation (8) into equation (7), we obtain:

y＝b ₀ +b ₁ x ₁ +b ₂ x ₂ (9)

According to the relation (9), the relation between the acoustic wave time difference curve of each rock layer in the wellbore and the depth parameters of each rock layer and the three-dimensional resistivity parameters of each rock layer is as follows:

y ₁ =b ₀ +b ₁ x ₁₁ +b ₂ x ₁₂

y ₂ =b ₀ +b ₁ x ₂₁ +b ₂ x ₂₂

y ₃ =b ₀ +b ₁ x ₃₁ +b ₂ x ₃₂

…………………………………………

y _i ＝b ₀ +b ₁ x _i1 +b ₂ x _i2

Solve b ₀ , b ₁ and b ₂ by using the formation acoustic logging data of the wellbore through the formation acoustic time difference curve;

Substitute the solved _b0 , _b1 and _b2 into equation (8) to solve A, N and M; Substitute A, N and M into equation (6) to complete the regression of the rock formation acoustic wave time difference curve between the rock formation depth and the rock formation three-way resistivity;

The rock formation acoustic wave time difference curve sound borehole is a rock formation acoustic wave time difference curve sound borehole which is closest to the missing rock formation acoustic wave time difference curve borehole in the same working area and the same formation system.

Further, the formation acoustic logging data of the well-established borehole of the formation acoustic time difference curve is composed of n formation acoustic logging data, and the i-th formation acoustic logging data includes the following parameters: formation acoustic time difference (△t) _i , formation depth H _i and formation three-dimensional resistivity (R _t ) _i ;

x ₁ ={x ₁₁ , x ₂₁ , x ₃₁ .. x _i1 }, where x _i1 is calculated by the curve regression module based on the formation acoustic wave time difference curve to improve the borehole formation depth _Hi ;

x ₂ ={x ₁₂ , x ₂₂ , x ₃₂ .. x _i2 }, where x _i2 is calculated by the curve regression module based on the three-dimensional resistivity depth (R _t ) _i of the well-established borehole rock formation based on the rock formation acoustic wave time difference curve;

y＝{y ₁ , y ₂ , y ₃ .. y _i }, y _i is calculated by the curve regression module according to the formation acoustic wave time difference curve of the well-established borehole formation acoustic wave time difference (△t) _i .

Furthermore, the curve regression module solves b ₀ , b ₁ and b ₂ by using the formation acoustic wave time difference curve to improve the formation acoustic wave logging data of the borehole, including the following steps:

The linear equations are constructed as follows:

L ₁₁ b ₁ +L ₁₂ b ₂ =L _1y (10)

L ₂₁ b ₁ +L ₂₂ b ₂ =L _2y (11)

in,

_L21 ＝ _L12 (14)

The following matrix is established to solve the linear equations:

Solve for b ₀ , b ₁ , and b ₂ .

Furthermore, the curve regression module evaluates the regression quality of the rock formation acoustic wave time difference regression curve between the rock formation acoustic wave time difference and the rock formation depth and the rock formation three-lateral resistivity through the fitting degree. The calculation formula of the fitting degree is as follows:

为岩层声波时差回归值；R²为拟和度。Where Ass is the sum of squares of acoustic time difference observations of each rock layer; Bss is the sum of squares of the difference between the acoustic time difference observations of each rock layer and the regression value; _yi is the acoustic time difference observation value of the rock layer;

is the regression value of the rock formation acoustic wave time difference; ^R2 is the degree of fit.

Furthermore, the curve regression module establishes the matrix (5) to solve the linear equations (9) and (10) to obtain b ₀ , b ₁ and b ₂ , including the following steps:

Call Excel software and perform the following steps:

The parameters of the formation acoustic logging data of the well-developed borehole of the formation acoustic time difference curve are stored in Excel workbooks by columns;

Calculate the logarithm of the acoustic time difference (△t) _i of each rock layer and the logarithm of the depth H _i of each rock layer by solving the logarithmic function "log()" respectively, and store the calculated log(△t) _i and logH _i in the Excel workbook by column respectively;

和

分别存储在所述Excel工作簿中；L ₁₁ , L ₁₂ , L ₂₁ , L ₂₂ , L _1y and L _2y are calculated respectively by equations (12)-(17), and the calculated L ₁₁ , L 12 , L ₂₁ , L ₂₂ , L _1y and L _2y are _converted into the matrix

and

are stored in the Excel workbook respectively;

的逆矩阵，通过求解矩阵积函数“MMULT()求解出矩阵

的逆矩阵和矩阵

的乘积，求解出b₁和b₂并存储在所述Excel工作簿中；Solve the matrix by solving the inverse matrix function "MINVERSE()"

The inverse matrix of the matrix is solved by solving the matrix product function "MMULT()

The inverse matrix and matrix

The product of is solved for _b1 and _b2 and stored in the Excel workbook;

According to the relation (18), _b0 is calculated and stored in the Excel workbook.

Furthermore, the curve regression module calls Excel software, substitutes the solved _b0 , _b1 and _b2 into the relationship (8), and solves A, N and M; substitutes A, N and M into the relationship (6) to complete the rock formation acoustic wave time difference curve regression between the rock formation depth and the rock formation three-way resistivity.

Furthermore, the curve regression module calls Excel software, substitutes the calculated b ₀ , b ₁ and b ₂ into equation (9), solves the regression value of the logarithm of the rock formation acoustic wave time difference and stores it in the Excel workbook by column;

The rock formation acoustic wave time difference regression value is solved by solving the antilogarithmic function "Power()" and stored in the Excel workbook by column;

According to equations (19)-(20), the square of the acoustic wave observation value of each rock layer Ass and the sum of the squares of the difference between the acoustic wave time difference observation value and the regression value of each rock layer Bss are calculated;

The goodness of fit R ² of the rock formation acoustic wave time difference regression curve is calculated according to equation (21).

The method and system for constructing the borehole rock formation acoustic wave time difference curve of the present invention are applied to the rock formation acoustic wave time difference curve regression of the rock formation acoustic wave time difference curve of the leachable sandstone type uranium ore rock formation ZKn0-3 in the × basin of the ×× area, and the regressed rock formation acoustic wave time difference curve fitting degree ^R2 is 96.13%.

The rock formation acoustic wave time difference regression curve of borehole ZKn0-3 is:

△t＝1499.271*H ^0.09294 *0.984 ^R t

Where △t is the acoustic time difference of the rock formation, in μs/m; H is the depth of the rock formation, in m; _Rt is the three-dimensional resistivity of the rock formation, in Ω·m.

Referring to Figure 3, the acoustic wave time difference curve of the rock formation of the in-situ leachable sandstone uranium ore in the × basin of the ×× area is compared with the rock formation acoustic wave time difference curve of the sound borehole ZKn0-3 and the actual measured rock formation acoustic wave time difference curve, and it can be seen that:

1. The measured rock formation acoustic wave time difference curve of borehole ZKn0-3 has no major fluctuations, and the curve is obviously tilted to the left from 130 to 443 meters; the rock formation acoustic wave time difference regression curve of borehole ZKn0-3 is obviously tilted to the left from 0 to 443 meters; the leftward tilt of the rock formation acoustic wave time difference curve indicates that the propagation speed of rock formation acoustic waves gradually increases with the increase of the effective pressure of the overlying stratum, and the rock formation acoustic wave time difference regression curve of borehole ZKn0-3 is more sensitive to the effective pressure of the overlying stratum than the measured rock formation acoustic wave time difference curve, and the measured rock formation density calculated from it is more accurate.

2. The measured rock formation acoustic time difference curve of borehole ZKn0-3 has no different reflection on the physical properties of the two major geological cycles in the borehole profile, the Cretaceous and Jurassic systems; the rock formation acoustic time difference regression curve of borehole ZKn0-3 has a greater difference reflection on the Cretaceous conglomerate. In the Cretaceous conglomerate, the rock formation acoustic time difference regression curve of borehole ZKn0-3 is in a mirror relationship with its three lateral resistivity curves, which clearly reflects the interface between the two major geological cycles of the Cretaceous and Jurassic systems. The rock formation acoustic time difference regression curve of borehole ZKn0-3 can more accurately reflect the physical properties of the rock formation than the measured rock formation acoustic time difference curve.

In Figure 3 , the enlarged horizontal scale causes the borehole to be tilted significantly.

The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims (12)

1. A method for constructing a borehole rock formation acoustic wave time difference curve, characterized in that it comprises the following steps: Step 1, constructing a relationship between the propagation velocity of rock sound waves and the rock depth and the three-dimensional resistivity of the rock; Step 2, substituting the relationship between the rock formation acoustic wave propagation velocity and the rock formation acoustic wave time difference into the relationship in step 1, and obtaining the relationship between the rock formation acoustic wave time difference and the rock formation depth and the three-dimensional resistivity of the rock formation; Step 3, regressing the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-dimensional resistivity of the formation according to the formation acoustic wave time difference curve of the formation acoustic wave logging data of the well borehole; Step 4: Use the formation acoustic time difference regression curve of step 3 as the formation acoustic time difference regression curve of the borehole where the formation acoustic time difference curve is missing, extract the parameters necessary for calculating the formation acoustic time difference from the formation acoustic logging data of the borehole where the formation acoustic time difference curve is missing, and substitute them into the formation acoustic time difference regression curve to calculate the formation acoustic time difference parameters of the borehole where the formation acoustic time difference curve is missing. 2. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 1, characterized in that in step 1, the relationship between the rock formation acoustic wave propagation velocity and the rock formation depth and the three-dimensional resistivity of the rock formation is:

Where V is the acoustic wave propagation velocity of the rock formation, in m/s; H is the depth of the rock formation, in m; _Rt is the three-dimensional resistivity of the rock formation, in Ω·m; M is the regional formation factor; A and N are unknown parameters. 3. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 2, characterized in that in step 2, the relationship between the rock formation acoustic wave propagation velocity and the rock formation acoustic wave time difference is as follows:

Substituting equation (3) into the equation in step 1, we get the following equation:

The statistical relationship between the acoustic time difference of the rock formation and the rock formation depth and the three-dimensional resistivity of the rock formation is obtained by sorting out the relationship (5):

Wherein, V is the propagation velocity of rock acoustic waves, in m/s; Δt is the rock acoustic wave time difference, in μs/m; H is the rock depth, in m; _Rt is the three-dimensional resistivity of the rock, in Ω·m; M is the regional formation factor; A and N are parameters to be determined. 4. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 3 is characterized in that step 3, regressing the rock formation acoustic wave time difference curve between the rock formation acoustic wave time difference and the rock formation depth and the three-dimensional resistivity of the rock formation according to the rock formation acoustic wave time difference curve to improve the rock formation acoustic wave logging data of the borehole, comprises the following steps: Step 3.1, take the logarithm of both sides of the relationship (6), and transpose the terms to obtain the following relationship:

Step 3.2: Substitute the variables in equation (7) and assume:

Step 3.3: Substitute equation (8) into equation (7) to obtain: y＝b ₀ +b ₁ x ₁ +b ₂ x ₂ (9) Step 3.4: Arrange the rock formation acoustic wave time difference curve according to the relationship (9) to improve the relationship between the acoustic wave time difference parameters of each rock formation in the borehole and the depth parameters of each rock formation and the three-dimensional resistivity parameters of each rock formation as follows: y ₁ =b ₀ +b ₁ x ₁₁ +b ₂ x ₁₂ y ₂ =b ₀ +b ₁ x ₂₁ +b ₂ x ₂₂ y ₃ =b ₀ +b ₁ x ₃₁ +b ₂ x ₃₂ ……………………………… y _i ＝b ₀ +b ₁ x _i1 +b ₂ x _i2 Step 3.5, using the formation acoustic wave time difference curve to improve the formation acoustic wave logging data of the borehole to solve b ₀ , b ₁ and b ₂ ; Step 3.6, substitute the solved _b0 , _b1 and _b2 into the relational expression (8) to solve A, N and M; substitute A, N and M into the relational expression (6) to complete the regression of the rock formation acoustic wave time difference curve between the rock formation depth and the rock formation three-way resistivity; The rock formation acoustic wave time difference curve sound borehole is a rock formation acoustic wave time difference curve sound borehole which is closest to the missing rock formation acoustic wave time difference curve borehole in the same working area and the same formation system. 5. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 4, characterized in that the rock formation acoustic wave time difference curve is composed of n rock formation acoustic wave logging data of the well-established borehole, and the i-th rock formation acoustic wave logging data includes the following parameters: rock formation acoustic wave time difference (Δt) _i , rock formation depth Hi and rock formation three-dimensional resistivity (R _t ) _i ; x ₁ ={x ₁₁ , x ₂₁ , x ₃₁ .. x _i1 }, x _i1 is calculated based on the sound borehole rock formation depth _Hi of the rock formation acoustic wave time difference curve; x ₂ ={x ₁₂ , x ₂₂ , x ₃₂ . . . x _i2 }, x _i2 is calculated based on the three-dimensional resistivity depth (R _t ) _i of the well-developed borehole rock formation based on the rock formation acoustic wave time difference curve; y＝{y ₁ , y ₂ , y ₃ . . . y _i }, y _i is calculated based on the formation acoustic wave time difference curve and the sound borehole formation acoustic wave time difference (Δt) _i . 6. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 5, characterized in that step 3.5, solving _b0 , _b1 and _b2 by using the rock formation acoustic wave time difference curve to improve the rock formation acoustic wave logging data of the borehole, comprises the following steps: Step 3.5.1, construct the linear equation system as follows: L ₁₁ b ₁ +L ₁ 2b ₂ =L _1y (10) L ₂₁ b ₁ +L ₂₂ b ₂ =L _2y (11) in,

_L21 ＝ _L12 (14)

Step 3.5.2, establish the following matrix to solve the linear equations:

Solve for b ₀ , b ₁ , and b ₂ . 7. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 6 is characterized in that the regression quality of the rock formation acoustic wave time difference regression curve between the rock formation acoustic wave time difference and the rock formation depth and the rock formation three-way resistivity is evaluated by the fitting degree, and the calculation formula of the fitting degree is as follows:

Where Ass is the sum of squares of acoustic time difference observations of each rock layer; Bss is the sum of squares of the difference between the acoustic time difference observations of each rock layer and the regression value; _yi is the acoustic time difference observation value of the rock layer;

is the regression value of the rock formation acoustic wave time difference; ^R2 is the degree of fit. 8. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 6, characterized in that step 3.5.2, establishing a matrix (5) to solve the linear equations (9) and (10) to solve _b0 , _b1 and _b2 , comprises the following steps: In Excel, follow these steps: The parameters of the formation acoustic logging data of the well-developed borehole of the formation acoustic time difference curve are stored in Excel workbooks by columns; Calculate the logarithm of the acoustic time difference (Δt) _i of each rock layer and the logarithm of the depth H _i of each rock layer by solving the logarithmic function "log()" respectively, and store the calculated log(Δt) _i and logH _i in the Excel workbook by column respectively; L ₁₁ , L ₁₂ , L ₂₁ , L ₂₂ , L _1y and L _2y are calculated respectively by equations (12)-(17), and the calculated L ₁₁ , L 12 , L ₂₁ , L ₂₂ , L _1y and L _2y are _converted into the matrix

and

are stored in the Excel workbook respectively; Solve the matrix by solving the inverse matrix function "MINVERSE()"

The inverse matrix of the matrix is solved by solving the matrix product function "MMULT()

The inverse matrix and matrix

The product of is solved for _b1 and _b2 and stored in the Excel workbook; According to the relation (18), _b0 is calculated and stored in the Excel workbook. 9. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 8, characterized in that, in step 3.6, in Excel software, the solved _b0 , _b1 and _b2 are substituted into relational formula (8) to solve A, N and M; A, N and M are substituted into relational formula (6) to complete the rock formation acoustic wave time difference curve regression between the rock formation acoustic wave time difference and the rock formation depth and the three lateral resistivity of the rock formation. 10. The method for constructing a borehole rock formation acoustic wave time difference curve according to claim 9, characterized in that, in Excel software, the calculated b ₀ , b ₁ and b ₂ are substituted into the relational equation (9), and the regression value of the logarithm of the rock formation acoustic wave time difference is solved and stored in the Excel workbook by column; The rock formation acoustic wave time difference regression value is solved by solving the antilogarithmic function "Power()" and stored in the Excel workbook by column; According to equations (19)-(20), the square Ass of the acoustic wave observation value of each rock layer and the sum of the squares of the difference between the acoustic wave time difference observation value and the regression value of each rock layer Bss are calculated; The goodness of fit R ² of the rock formation acoustic wave time difference regression curve is calculated according to equation (21). 11. The method for constructing a borehole rock formation acoustic wave time difference curve according to any one of claims 1 to 10, characterized in that, in step 4, the rock formation acoustic wave logging data of the borehole with missing rock formation acoustic wave time difference curve includes the following parameters: rock formation depth H and rock formation three-dimensional resistivity _Rt . 12. A drilling rock formation acoustic wave time difference curve construction system, characterized by comprising: A data acquisition module is used to acquire the formation acoustic logging data of the borehole with a sound formation acoustic time difference curve and the formation acoustic logging data of the borehole with a missing formation acoustic time difference curve, and send the formation acoustic logging data of the borehole with a sound formation acoustic time difference curve to the curve regression module, and send the formation acoustic logging data of the borehole with a missing formation acoustic time difference curve to the parameter calculation module; The curve regression module is used to receive the formation acoustic wave time difference curve sent by the data acquisition module to improve the formation acoustic wave logging data of the borehole, and regress the formation acoustic wave time difference curve between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation according to the relationship between the formation acoustic wave time difference and the formation depth and the three-lateral resistivity of the formation, and send it to the parameter calculation module; The parameter calculation module is used to receive the rock formation acoustic logging data of the borehole with missing rock formation acoustic time difference curve sent by the data acquisition module and the rock formation acoustic time difference regression curve sent by the curve regression module, extract the parameters necessary for calculating the rock formation acoustic time difference from the rock formation acoustic logging data of the borehole with missing rock formation acoustic time difference curve, substitute them into the rock formation acoustic time difference regression curve, and calculate the rock formation acoustic time difference parameters of the borehole with missing rock formation acoustic time difference curve.

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