A method and system for constructing an acoustic travel-time curve of a drilled rock formation

Abstract

The present invention specifically relates to a method for constructing an acoustic wave travel time curve of a drilled rock formation, including: establishing a relational expression between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the three lateral resistivities of the rock formation; sorting out a relational expression between the acoustic wave travel time of the rock formation, the depth of the rock formation, and the three lateral resistivities of the rock formation; based on the acoustic wave travel time curve of the rock formation, improving the acoustic wave logging data of the drilled rock formation to regress an acoustic wave travel time curve of the rock formation between the acoustic wave travel time of the rock formation, the depth of the rock formation, and the three lateral resistivities of the rock formation; extracting parameters necessary for calculating the acoustic wave travel time of the rock formation from the acoustic wave logging data of the drilled hole lacking the acoustic wave travel time curve of the rock formation and substituting them into the acoustic wave travel time regression curve of the rock formation to calculate the acoustic wave travel time parameters of the drilled hole lacking the acoustic wave travel time curve of the rock formation. The method for constructing an acoustic wave travel time curve of a drilled rock formation according to the present invention can obtain the acoustic wave travel time parameters of a drilled hole lacking the acoustic wave travel time curve of the rock formation to obtain the true density of the rock formation underground.

Description

Technical Field

[0001] The present invention relates to the technical field of exploration of in-situ leachable sandstone-type uranium deposits, and particularly to a method and a system for constructing an acoustic wave travel-time curve of borehole rock strata. Background Art

[0002] In the field comprehensive logging work for searching in-situ leachable sandstone-type uranium deposits, the acoustic wave probe often fails due to poor working conditions and rough and bumpy road conditions. If the failure of the acoustic wave probe cannot be eliminated on the logging site, it is necessary to abandon the measurement of the acoustic wave travel-time parameters of the borehole rock strata. The acoustic wave travel-time parameters of the rock strata can effectively distinguish sandstone and mudstone in the sand-mudstone section.

[0003] Since the acoustic wave propagation velocity of the rock strata is closely related to the density of the rock strata, the acoustic wave travel-time of the rock strata is an effective logging parameter for detecting the true density of the rock strata underground. According to scientific research, within the burial depth range of less than 1700 meters, that is, the effective pressure is less than 20 MPa, the acoustic wave propagation velocity of the rock strata increases with the increase of the effective pressure of the overlying strata, and the rock density increases with the increase of the acoustic wave propagation velocity of the rock strata.

[0004] The exploration borehole depth for searching in-situ leachable sandstone-type uranium deposits just falls within the burial depth section of less than 1700 meters, that is, the effective pressure is less than 20 MPa. The close relationship between the acoustic wave propagation velocity of the rock strata and the rock density enables the change of the rock density to be obtained through the change of the acoustic wave propagation velocity of the rock strata during the exploration of in-situ leachable sandstone-type uranium deposits.

[0005] During the exploration of in-situ leachable sandstone-type uranium deposits, if the acoustic wave travel-time parameters of the rock strata are accidentally missing due to field logging, the density of the rock strata is generally measured by the γ-γ method. However, due to the pressure relief effect of the borehole and the shallow radial detection depth itself, the density measured by the γ-γ method is not the true density of the rock strata underground, but the density after the rock strata are pressure-relieved. Therefore, during the exploration of in-situ leachable sandstone-type uranium deposits, the accidental missing of the acoustic wave travel-time parameters of the rock strata due to field logging will result in the inability to obtain the true density of the rock strata underground. Summary of the Invention

[0006] Based on this, in view of the problem that the accidental missing of the acoustic wave travel-time parameters of the rock strata due to field logging during the exploration of in-situ leachable sandstone-type uranium deposits leads to the inability to obtain the true density of the rock strata underground, the present invention provides a method and a system for constructing an acoustic wave travel-time curve of borehole rock strata. The method and the system regress the acoustic wave logging data of the borehole rock strata according to the complete acoustic wave travel-time curve of the borehole rock strata to obtain the acoustic wave travel-time regression curve of the borehole with the missing acoustic wave travel-time curve, so as to obtain the acoustic wave travel-time parameters of the borehole with the missing acoustic wave travel-time curve, and thus obtain the true density of the rock strata underground.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for constructing the acoustic travel time curve of a drilled rock formation, comprising the following steps:

[0009] Step 1, construct a relational expression between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation;

[0010] Step 2, substitute the relational expression between the acoustic wave propagation velocity of the rock formation and the acoustic travel time of the rock formation into the relational expression of Step 1, and after arrangement, obtain the relational expression between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation;

[0011] Step 3, based on the acoustic travel time curve of the drilled rock formation, improve the acoustic logging data of the drilled rock formation, and regress the acoustic travel time curve between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation;

[0012] Step 4, use the acoustic travel time regression curve of Step 3 as the acoustic travel time regression curve of the drilled hole with the missing acoustic travel time curve, extract the parameters necessary for calculating the acoustic travel time of the rock formation from the acoustic logging data of the drilled hole with the missing acoustic travel time curve, and substitute them into the acoustic travel time regression curve to calculate the acoustic travel time parameters of the drilled hole with the missing acoustic travel time curve.

[0013] Further, in Step 1, the relational expression between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation is:

[0014]

[0015] In the formula, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; H is the depth of the rock formation, with the unit of m; R t is the triple lateral resistivity of the rock formation, with the unit of Ω·m; M is the formation factor of the area; A and N are undetermined parameters.

[0016] Further, according to the rock acoustics theory, the relational expression between the acoustic wave propagation velocity of the rock formation and the acoustic travel time of the rock formation is as follows:

[0017]

[0018] Substitute the relational expression (3) into the relational expression of Step 1 to obtain the following relational expression:

[0019]

[0020] Arrange the relational expression (5) to obtain the statistical relational expression between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation:

[0021]

[0022] Wherein, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; △t is the acoustic wave travel time difference of the rock formation, with the unit of μs / m; H is the depth of the rock formation, with the unit of m; R t is the triple lateral resistivity of the rock formation, with the unit of Ω·m; M is the formation factor of the area; A and N are undetermined parameters.

[0023] Furthermore, in step 3, based on the acoustic wave travel time difference curve of the rock formation, the acoustic wave logging data of the borehole is improved, and the acoustic wave travel time difference curve between the acoustic wave travel time difference of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation is regressed, including the following steps:

[0024] Step 3.1: Take the logarithm of both sides of the relational expression (6) and transpose and organize to obtain the following relational expression:

[0025]

[0026] Step 3.2: For the convenience of calculation, make a substitution for the relational expression (7), and set:

[0027]

[0028] Step 3.3: Substitute the relational expression (8) into the relational expression (7) to obtain:

[0029] y = b 0 +b 1 x 1 +b 2 x 2 (9)

[0030] Step 3.4: Organize the relational expression between the acoustic wave travel time difference parameters of each rock formation, the depth parameters of each rock formation, and the triple lateral resistivity parameters of each rock formation in the acoustic wave travel time difference curve of the improved borehole according to the relational expression (9) as follows:

[0031] y 1 = b 0 +b 1 x 11 +b 2 x 12

[0032] y 2 = b 0 +b 1 x 21 +b 2 x 22

[0033] y 3 = b 0 +b 1 x 31 +b 2 x 32

[0034] …………………………………………………………………

[0035] y i = b 0 + b 1 x i1 + b 2 x i2

[0036] Step 3.5. Solve for b by using the sonic log data of the borehole with a complete sonic travel-time curve of the rock formation 0 , b 1 and b 2 ;

[0037] Step 3.6. Substitute the solved b 0 , b 1 and b 2 into the relational expression (8) to solve for A, N, and M; substitute A, N, and M into the relational expression (6) to complete the regression of the sonic travel-time curve of the rock formation between the sonic travel-time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation;

[0038] The borehole with a complete sonic travel-time curve of the rock formation is the borehole with a complete sonic travel-time curve of the rock formation that is closest to the borehole lacking the sonic travel-time curve of the rock formation in the same working area and the same stratigraphic system.

[0039] Furthermore, the sonic log data of the borehole with a complete sonic travel-time curve of the rock formation consists of n sonic log data. The i-th sonic log data includes the following parameters: sonic travel-time of the rock formation (Δt) i , depth of the rock formation H i and triple lateral resistivity of the rock formation (R t ) i ;

[0040] x 1 = {x 11 , x 21 , x 31 …x i1}, x i1 is calculated based on the depth of the rock formation H i of the borehole with a complete sonic travel-time curve of the rock formation;

[0041] x 2 = {x 12 , x 22 , x 32 …x i2}, x i2 is calculated based on the depth of the triple lateral resistivity of the rock formation (R t ) i of the borehole with a complete sonic travel-time curve of the rock formation;

[0042] y = {y 1 , y 2 , y 3 …y i}, y i is calculated based on the sonic transit time curve of the rock formation to improve the sonic transit time (Δt) of the borehole rock formation i .

[0043] Furthermore, in step 3.5, solve for b, b, and b from the sonic logging data of the borehole rock formation through the sonic transit time curve of the rock formation 0 , b 1 , and b 2 , including the following steps:

[0044] Step 3.5.1: Construct the following system of linear equations:

[0045] L 11 b 1 + L 12 b 2 = L 1y (10)

[0046] L 21 b 1 + L 22 b 2 = L 2y (11)

[0047] where

[0048]

[0049]

[0050] L 21 = L 12 (14)

[0051]

[0052]

[0053]

[0054]

[0055] Step 3.5.2: Establish the following matrix to solve the system of linear equations:

[0056]

[0057] Solve for b, b, and b 0 , b 1 , and b 2 .

[0058] Further, the fitting degree is used to evaluate the regression quality of the regression curve of the acoustic wave travel time of the rock formation with respect to the depth of the rock formation and the triple lateral resistivity of the rock formation. The calculation formula for the fitting degree is as follows:

[0059]

[0060]

[0061]

[0062] In the formula, Ass is the sum of the squares of the observed values of the acoustic wave travel time of each rock formation; Bss is the sum of the squares of the differences between the observed values and the regression values of the acoustic wave travel time of each rock formation; y i is the observed value of the acoustic wave travel time of the rock formation; is the regression value of the acoustic wave travel time of the rock formation; R 2 is the fitting degree.

[0063] Further, in step 3.5.2, establish matrix (5) to solve the linear equations (9) and (10) to solve for b 0 、b 1 and b 2 , including the following steps:

[0064] In Excel software, perform the following steps:

[0065] Store each parameter of the acoustic wave logging data of the sound borehole of the acoustic wave travel time curve of the rock formation in the Excel workbook by column;

[0066] Calculate the logarithm of the acoustic wave travel time (△t) i of each rock formation and the depth H i of each rock formation respectively by solving the logarithmic function "log()", and store the calculated log(△t) i and logH i in the Excel workbook by column respectively;

[0067] Calculate L 11 、L 12 、L 21 、L 22 、L 1y and L 2y through the relational expressions (12)-(17), and store the calculated L 11 、L 12 、L 21 、L 22 、L 1y and L 2y in the matrix and in the Excel workbook by column respectively;

[0068] The inverse matrix of the matrix is solved by solving the inverse matrix function "MINVERSE()". The inverse matrix of the matrix is solved by solving the matrix product function "MMULT()". The product of the inverse matrix of the matrix and the matrix is solved to obtain b and b 1 and b 2 and stored in the Excel workbook;

[0069] b is calculated according to the relational expression (18). 0 and stored in the Excel workbook.

[0070] Furthermore, in step 3.6, in Excel software, the obtained b 0 , b 1 and b 2 are substituted into the relational expression (8) to solve for A, N, and M; A, N, and M are substituted into the relational expression (6) to complete the regression of the formation acoustic travel time curve between the formation acoustic travel time, the formation depth, and the formation triple lateral resistivity.

[0071] Furthermore, in Excel software, the calculated b 0 , b 1 and b 2 are substituted into the relational expression (9) to solve for the regression value of the logarithm of the formation acoustic travel time and store it in the Excel workbook column by column;

[0072] The regression value of the formation acoustic travel time is solved by solving the antilogarithm function "Power()" and stored in the Excel workbook column by column;

[0073] According to the relational expressions (19)-(20), the square Ass of the observed values of the acoustic waves of each formation is calculated, as well as the sum of squares Bss of the differences between the observed values and the regression values of the acoustic travel time of each formation;

[0074] According to the relational expression (21), the fitting degree R of the formation acoustic travel time regression curve is calculated 2 .

[0075] Furthermore, in step 4, the formation acoustic logging data of the borehole with the missing formation acoustic travel time curve includes the following parameters: formation depth H and formation triple lateral resistivity R t .

[0076] The present invention also provides a system for constructing a formation acoustic travel time curve of a borehole, including:

[0077] A data acquisition module, which is configured to acquire the borehole acoustic logging data of the boreholes with complete formation acoustic travel-time curves and the borehole acoustic logging data of the boreholes without formation acoustic travel-time curves, and send the borehole acoustic logging data of the boreholes with complete formation acoustic travel-time curves to the curve regression module and send the borehole acoustic logging data of the boreholes without formation acoustic travel-time curves to the parameter calculation module;

[0078] A curve regression module, which is configured to receive the borehole acoustic logging data of the boreholes with complete formation acoustic travel-time curves sent by the data acquisition module, and regress the formation acoustic travel-time curve between the formation acoustic travel-time and the formation depth and the formation triple lateral resistivity according to the relational expression between the formation acoustic travel-time and the formation depth and the formation triple lateral resistivity, and send it to the parameter calculation module;

[0079] A parameter calculation module, which is configured to receive the borehole acoustic logging data of the boreholes without formation acoustic travel-time curves sent by the data acquisition module and the formation acoustic travel-time regression curve sent by the curve regression module, extract the parameters necessary for calculating the formation acoustic travel-time from the borehole acoustic logging data of the boreholes without formation acoustic travel-time curves and substitute them into the formation acoustic travel-time regression curve to calculate the formation acoustic travel-time parameters of the boreholes without formation acoustic travel-time curves.

[0080] Further, the relational expression between the formation acoustic travel-time and the formation depth and the formation triple lateral resistivity is:

[0081]

[0082] In the formula, V is the formation acoustic wave propagation velocity, with the unit of m / s; △t is the formation acoustic travel-time, with the unit of μs / m; H is the formation depth, with the unit of m; R t is the formation triple lateral resistivity, with the unit of Ω·m; M is the regional formation factor; A and N are undetermined parameters.

[0083] Further, the curve regression module receives the borehole acoustic logging data of the boreholes with complete formation acoustic travel-time curves sent by the data acquisition module, and regresses the formation acoustic travel-time curve between the formation acoustic travel-time and the formation depth and the formation triple lateral resistivity according to the relational expression between the formation acoustic travel-time and the formation depth and the formation triple lateral resistivity, including the following steps:

[0084] Take the logarithm of both sides of the relational expression (6) and transpose and organize to obtain the following relational expression:

[0085]

[0086] Perform variable substitution on the relational expression (7), and set:

[0087]

[0088] Substituting the relational expression (8) into the relational expression (7) gives:

[0089] y = b 0 + b 1 x 1 + b 2 x 2 (9)

[0090] According to the relational expression (9), the relational expression between the acoustic wave slowness parameters of each rock stratum, the depth parameters of each rock stratum, and the triple lateral resistivity parameters of each rock stratum in the sound well logging data of the rock stratum is sorted out as follows:

[0091] y 1 = b 0 + b 1 x 11 + b 2 x 12

[0092] y 2 = b 0 + b 1 x 21 + b 2 x 22

[0093] y 3 = b 0 + b 1 x 31 + b 2 x 32

[0094] …………………………………………………………………

[0095] y i = b 0 + b 1 x i1 + b 2 x i2

[0096] Solve for b 0 , b 1 and b 2 ;

[0097] Substitute the solved b 0 , b 1 and b 2 into the relational expression (8) to solve for A, N, and M; substitute A, N, and M into the relational expression (6) to complete the regression of the acoustic wave slowness curve between the acoustic wave slowness of the rock stratum, the depth of the rock stratum, and the triple lateral resistivity of the rock stratum;

[0098] The borehole with a sound formation acoustic travel time curve is the borehole with a sound formation acoustic travel time curve that is closest to the borehole lacking a formation acoustic travel time curve in the same working area and the same formation system.

[0099] Further, the formation acoustic logging data of the borehole with a sound formation acoustic travel time curve consists of n formation acoustic logging data. The i-th formation acoustic logging data includes the following parameters: formation acoustic travel time (Δt) i , formation depth H i and formation triple lateral resistivity (R t ) i ;

[0100] x 1 ={x 11 , x 21 , x 31 …x i1}, x i1 is calculated by the curve regression module based on the formation depth H i of the borehole with a sound formation acoustic travel time curve;

[0101] x 2 ={x 12 , x 22 , x 32 …x i2}, x i2 is calculated by the curve regression module based on the formation triple lateral resistivity depth (R t ) i of the borehole with a sound formation acoustic travel time curve;

[0102] y={y 1 , y 2 , y 3 …y i}, y i is calculated by the curve regression module based on the formation acoustic travel time (Δt) i of the borehole with a sound formation acoustic travel time curve.

[0103] Further, the curve regression module solves for b 0 , b 1 and b 2 through the formation acoustic logging data of the borehole with a sound formation acoustic travel time curve, including the following steps:

[0104] Construct the following system of linear equations:

[0105] L 11 b 1 +L 12 b 2 =L 1y (10)

[0106] L 21 b 1 +L 22 b 2 =L 2y (11)

[0107] Among them,

[0108]

[0109]

[0110] L 21 =L 12 (14)

[0111]

[0112]

[0113]

[0114]

[0115] Establish the following matrix to solve the said system of linear equations:

[0116]

[0117] Solve for b 0 、b 1 and b 2 。

[0118] Furthermore, the curve regression module evaluates the regression quality of the regression curve of the acoustic wave travel time of rock formations with respect to the depth of rock formations and the triple lateral resistivity of rock formations through the goodness of fit. The calculation formula for the goodness of fit is as follows:

[0119]

[0120]

[0121]

[0122] In the formula, Ass is the sum of the squares of the observed values of the acoustic wave travel time of each rock formation; Bss is the sum of the squares of the differences between the observed values and the regression values of the acoustic wave travel time of each rock formation; y i is the observed value of the acoustic wave travel time of the rock formation; is the regression value of the acoustic wave travel time of the rock formation; R 2 is the goodness of fit.

[0123] Furthermore, the curve regression module establishes matrix (5) to solve the systems of linear equations (9) and (10), and solves for b 0 、b 1 and b2 , including the following steps:

[0124] Call Excel software and execute the following steps:

[0125] Store each parameter of the borehole acoustic logging data of the formation acoustic travel-time curve in columns in an Excel workbook;

[0126] Calculate the formation acoustic travel-time (Δt) of each formation by solving the logarithmic function "log()" i and the depth H of each formation i of the logarithm and store the calculated log(Δt) i and logH i in columns in the Excel workbook respectively;

[0127] Calculate L 11 , L 12 , L 21 , L 22 , L 1y and L 2y through the relational expressions (12)-(17), and store the calculated L 11 , L 12 , L 21 , L 22 , L 1y and L 2y in the Excel workbook according to the matrices and respectively;

[0128] Solve the inverse matrix of the matrix by solving the inverse matrix function "MINVERSE()", and solve the product of the inverse matrix of the matrix and the matrix by solving the matrix product function "MMULT()", and solve for b 1 and b 2 and store them in the Excel workbook;

[0129] Calculate b 0 according to the relational expression (18) and store it in the Excel workbook.

[0130] Furthermore, the curve regression module calls Excel software, substitutes the solved b 0 , b 1 and b 2 into the relational expression (8) to solve for A, N, and M; substitute A, N, and M into the relational expression (6) to complete the regression of the formation acoustic travel-time curve between the formation acoustic travel-time and the formation depth and the formation triple lateral resistivity.

[0131] Further, the curve regression module calls Excel software, substitutes the calculated b 0 , b 1 and b 2 into the relational expression (9), solves the regression value of the logarithm of the acoustic wave travel time of the rock formation, and stores it in the Excel workbook column by column;

[0132] Solves the regression value of the acoustic wave travel time of the rock formation by solving the antilogarithm function "Power()" and stores it in the Excel workbook column by column;

[0133] Calculates the square Ass of the acoustic wave observation values of each rock formation and the sum of squares Bss of the differences between the acoustic wave travel time observation values and the regression values of each rock formation according to the relational expressions (19)-(20);

[0134] Calculates the fitting degree R 2 of the regression curve of the acoustic wave travel time of the rock formation according to the relational expression (21).

[0135] Advantageous technical effects of the present invention:

[0136] The method and system for constructing the acoustic wave travel time curve of borehole rock formations of the present invention regress the acoustic wave travel time regression curve of the borehole with missing acoustic wave travel time curve based on the acoustic wave travel time curve of the borehole and the sound wave logging data of the rock formation; the acoustic wave travel time regression curve of the rock formation is more sensitive to the effective pressure of the overlying formation than the measured acoustic wave travel time curve of the rock formation, and the measured rock density calculated therefrom is more accurate; the acoustic wave travel time regression curve of the rock formation can more accurately reflect the physical properties of the rock formation than the measured acoustic wave travel time curve of the rock formation. Description of the Drawings

[0137] Figure 1 is a schematic flow chart of the method for constructing the acoustic wave travel time curve of borehole rock formations of the present invention;

[0138] Figure 2 is a schematic structural diagram of the system for constructing the acoustic wave travel time curve of borehole rock formations of the present invention;

[0139] Figure 3 is a comparison diagram of the regression curve of the acoustic wave travel time of the rock formation and the measured acoustic wave travel time curve of the rock formation. Detailed Embodiments

[0140] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings and specific embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0141] See Figure 1, the present invention provides a method for constructing an acoustic travel time curve of a drilled rock formation, comprising the following steps:

[0142] Step 1, construct a relational expression between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation;

[0143] Step 2, substitute the relational expression between the acoustic wave propagation velocity of the rock formation and the acoustic travel time of the rock formation into the relational expression of Step 1, and after arrangement, obtain the relational expression between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation;

[0144] Step 3, based on the acoustic travel time curve of the drilled rock formation, sound the acoustic logging data of the drilled rock formation to regress the acoustic travel time curve between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation;

[0145] Step 4, use the acoustic travel time regression curve of Step 3 as the acoustic travel time regression curve of the drilled hole with the missing acoustic travel time curve, extract the parameters necessary for calculating the acoustic travel time of the rock formation from the acoustic logging data of the drilled hole with the missing acoustic travel time curve, and substitute them into the acoustic travel time regression curve to calculate the acoustic travel time parameters of the drilled hole with the missing acoustic travel time curve.

[0146] Further, in Step 1, the relational expression between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation is:

[0147] V = A * H N * M R t(4)

[0148] In the formula, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; H is the depth of the rock formation, with the unit of m; R t is the triple lateral resistivity of the rock formation, with the unit of Ω·m; M is the formation factor of the region; A and N are undetermined parameters.

[0149] In the late 1940s and early 1950s, Foster studied well logging data of over one million feet, compared the triple lateral resistivity of the rock formation with the acoustic wave propagation velocity of the rock formation, and obtained the relational expression between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation:

[0150] V = K * H * C * d * Rt(1)

[0151] In the formula, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; H is the depth of the rock formation, with the unit of m; R t is the resistivity of the triple lateral resistivity of the rock formation, with the unit of Ω·m; K, C, and d are all parameters, selected according to different regions, dimensionless.

[0152] Through a large number of acoustic experiments, the petroleum system has studied the relationship between the acoustic wave propagation velocity of rock formations, the depth of rock formations, and the effective pressure of the overlying strata of rock formations:

[0153] V = a*(PH) c (2)

[0154] In the formula, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; P is the effective pressure of the overlying strata of the rock formation, with the unit of KPa / h; H is the depth of the rock formation, with the unit of m; a and c are both parameters.

[0155] Based on the relationship between the acoustic wave propagation velocity of rock formations, the three lateral resistivity of rock formations, the depth of rock formations, and the effective pressure of the overlying strata of rock formations studied by predecessors, the inventor innovatively proposed a relationship between the acoustic wave propagation velocity of rock formations, the depth of rock formations, and the three lateral resistivity of rock formations:

[0156]

[0157] In the formula, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; H is the depth of the rock formation, with the unit of m; R t is the three lateral resistivity of the rock formation, with the unit of Ω·m; M is the formation factor of the area; A and N are undetermined parameters.

[0158] Furthermore, according to the rock acoustics theory, the relationship between the acoustic wave propagation velocity of rock formations and the acoustic wave travel time difference of rock formations is as follows:

[0159]

[0160] Substitute the relationship formula (3) into the relationship formula in step 1 to obtain the following relationship formula:

[0161]

[0162] After organizing the relationship formula (5), a statistical relationship between the acoustic wave travel time difference of rock formations, the depth of rock formations, and the three lateral resistivity of rock formations is obtained:

[0163]

[0164] In the formula, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; △t is the acoustic wave travel time difference of the rock formation, with the unit of μs / m; H is the depth of the rock formation, with the unit of m; R t is the three lateral resistivity of the rock formation, with the unit of Ω·m; M is the formation factor of the area; A and N are undetermined parameters.

[0165] After being verified by a large number of sound wave time difference curve sound hole practices of rock formations, the fitting degree between the rock formation sound wave time difference parameters obtained by regression according to the relational expression (6) proposed by the present invention and the actually measured rock formation sound wave time difference parameters is above 90%, and satisfactory results are obtained. The practical verification results prove that the relational expression (6) proposed by the present invention is correct and feasible.

[0166] Further, in step 3, the sound wave logging data of the rock formation sound hole is regressed according to the sound wave time difference curve of the rock formation to obtain the sound wave time difference curve between the sound wave time difference of the rock formation and the rock formation depth and the three lateral resistivities of the rock formation, including the following steps:

[0167] Step 3.1: Take the logarithm of both sides of the relational expression (6), and transpose and organize to obtain the following relational expression:

[0168]

[0169] Step 3.2: For the convenience of calculation, make a substitution for the relational expression (7), and set:

[0170]

[0171] Step 3.3: Substitute the relational expression (8) into the relational expression (7) to obtain:

[0172] y = b 0 +b 1 x 1 +b 2 x 2 (9)

[0173] Step 3.4: Organize the relational expression between the sound wave time difference parameters of each rock formation, the depth parameters of each rock formation, and the three lateral resistivity parameters of each rock formation in the sound hole of the sound wave time difference curve of the rock formation according to the relational expression (9) as follows:

[0174] y 1 =b 0 +b 1 x 11 +b 2 x 12

[0175] y 2 =b 0 +b 1 x 21 +b 2 x 22

[0176] y 3 =b 0 +b 1 x 31 +b 2 x 32

[0177] …………………………………………………………………

[0178] y i = b 0 + b 1 x i1 + b 2 x i2

[0179] Step 3.5. Solve for b by improving the borehole's borehole acoustic logging data with the formation acoustic travel time curve 0 , b 1 and b 2 ;

[0180] Step 3.6. Substitute the solved b 0 , b 1 and b 2 into relation (8) to solve for A, N, and M; substitute A, N, and M into relation (6) to complete the regression of the formation acoustic travel time curve between the formation acoustic travel time and the formation depth and the formation triple lateral resistivity;

[0181] The borehole with the improved formation acoustic travel time curve is the borehole with the soundest formation acoustic logging data in the same working area and the same stratigraphic system that is closest to the borehole lacking the formation acoustic travel time curve.

[0182] Furthermore, the borehole acoustic logging data of the borehole with the improved formation acoustic travel time curve consists of n borehole acoustic logging data, and the i-th borehole acoustic logging data includes the following parameters: formation acoustic travel time (Δt) i , formation depth H i and formation triple lateral resistivity (R t ) i ;

[0183] x 1 = {x 11 , x 21 , x 31 … x i1}, x i1 is calculated based on the formation depth H i of the borehole with the improved formation acoustic travel time curve;

[0184] x 2 = {x 12 , x 22 , x 32 … x i2}, x i2 is calculated based on the formation triple lateral resistivity depth (R t ) i of the borehole with the improved formation acoustic travel time curve;

[0185] y = {y 1 , y 2 , y 3 … y i}}, y i is calculated based on the sonic travel time curve of the rock formation to improve the sonic travel time (Δt) of the borehole rock formation i .

[0186] Furthermore, in step 3.5, solve for b, b, and b from the sonic logging data of the borehole rock formation through the sonic travel time curve of the rock formation, including the following steps: 0 b 1 and b 2 :

[0187] Step 3.5.1: Construct the following system of linear equations:

[0188] L 11 b 1 + L 12 b 2 = L 1y (10)

[0189] L 21 b 1 + L 22 b 2 = L 2y (11)

[0190] where

[0191]

[0192]

[0193] L 21 = L 12 (14)

[0194]

[0195]

[0196]

[0197]

[0198] Step 3.5.2: Establish the following matrix to solve the system of linear equations:

[0199]

[0200] Solve for b, b, and b 0 b 1 and b 2 .

[0201] Furthermore, the regression quality of the regression curve of the formation acoustic wave travel time between the formation acoustic wave travel time and the formation depth and the formation triple lateral resistivity is evaluated by the fitting degree. The calculation formula of the fitting degree is as follows:

[0202]

[0203]

[0204]

[0205] In the formula, Ass is the sum of the squares of the observed values of the acoustic wave travel time of each formation; Bss is the sum of the squares of the differences between the observed values and the regression values of the acoustic wave travel time of each formation; y i is the observed value of the formation acoustic wave travel time; is the regression value of the formation acoustic wave travel time; R 2 is the fitting degree.

[0206] The fitting degree R 2 refers to the fitting degree of the regression curve to the observed values. The maximum value of R 2 is 1. The closer R 2 is to 1, the better the fitting degree of the regression curve to the observed values, the higher the explanatory degree of the independent variable to the dependent variable, the higher the percentage of the change caused by the independent variable in the total change, and the denser the observation points near the regression curve. On the contrary, the smaller the value of R 2 , the worse the fitting degree of the regression curve to the observed values, and the fewer the observation points near the regression curve.

[0207] Furthermore, in step 3.5.2, establish the matrix (5) to solve the linear equations (9) and (10), and solve for b 0 , b 1 and b 2 , including the following steps:

[0208] In the Excel software, perform the following steps:

[0209] Store the parameters of the formation acoustic wave logging data of the formation acoustic wave travel time curve sound hole in columns in the Excel workbook respectively;

[0210] Calculate the logarithms of the acoustic wave travel time (△t) of each formation i and the depth H of each formation i respectively by solving the logarithmic function "log()", and store the calculated log(△t) i and logH i in columns in the Excel workbook respectively;

[0211] Calculate L 11 , L12 and L 21 and L 22 and L 1y and L 2y , and store the calculated L 11 and L 12 and L 21 and L 22 and L 1y and L 2y in the Excel workbook according to the matrices and respectively;

[0212] Solve the inverse matrix of matrix by using the inverse matrix function "MINVERSE()", and solve the product of the inverse matrix of matrix and matrix by using the matrix product function "MMULT()", and solve for b 1 and b 2 and store them in the Excel workbook;

[0213] Calculate b 0 according to the relational expression (18) and store it in the Excel workbook.

[0214] Furthermore, in step 3.6, in Excel software, substitute the solved b 0 , b 1 and b 2 into the relational expression (8) to solve for A, N, and M; substitute A, N, and M into the relational expression (6) to complete the regression of the formation acoustic travel time curve between the formation acoustic travel time, the formation depth, and the formation triple lateral resistivity.

[0215] Furthermore, in Excel software, substitute the calculated b 0 , b 1 and b 2 into the relational expression (9) to solve for the regression value of the logarithm of the formation acoustic travel time and store it in the Excel workbook by column;

[0216] Solve for the regression value of the formation acoustic travel time by using the antilogarithm function "Power()" and store it in the Excel workbook by column;

[0217] Calculate the square Ass of the observed values of the acoustic waves of each formation, and the sum of squares Bss of the differences between the observed values and the regression values of the acoustic travel times of each formation according to the relational expressions (19)-(20);

[0218] Calculate the goodness of fit R 2 of the formation acoustic travel time regression curve according to the relational expression (21).

[0219] Further, in step 4, the borehole acoustic logging data of the missing formation acoustic travel time curve borehole includes the following parameters: formation depth H and formation triple lateral resistivity R t .

[0220] See Figure 2 , the present invention also provides a system for constructing a borehole formation acoustic travel time curve, including:

[0221] A data acquisition module, configured to acquire the borehole acoustic logging data of the formation acoustic travel time curve sound borehole and the borehole acoustic logging data of the missing formation acoustic travel time curve borehole, and send the borehole acoustic logging data of the formation acoustic travel time curve sound borehole to the curve regression module, and send the borehole acoustic logging data of the missing formation acoustic travel time curve borehole to the parameter calculation module;

[0222] A curve regression module, configured to receive the borehole acoustic logging data of the formation acoustic travel time curve sound borehole sent by the data acquisition module, and according to the relational formula between the formation acoustic travel time and the formation depth and the formation triple lateral resistivity, regress the formation acoustic travel time curve between the formation acoustic travel time and the formation depth and the formation triple lateral resistivity and send it to the parameter calculation module;

[0223] A parameter calculation module, configured to receive the borehole acoustic logging data of the missing formation acoustic travel time curve borehole sent by the data acquisition module and the formation acoustic travel time regression curve sent by the curve regression module, extract the parameters necessary for calculating the formation acoustic travel time from the borehole acoustic logging data of the missing formation acoustic travel time curve borehole and substitute them into the formation acoustic travel time regression curve, and calculate the formation acoustic travel time parameters of the missing formation acoustic travel time curve borehole.

[0224] Further, the relational formula between the formation acoustic travel time and the formation depth and the formation triple lateral resistivity is:

[0225]

[0226] In the formula, V is the formation acoustic wave propagation velocity, with the unit of m / s; △t is the formation acoustic travel time, with the unit of μs / m; H is the formation depth, with the unit of m; R t is the formation triple lateral resistivity, with the unit of Ω·m; M is the regional formation factor; A and N are undetermined parameters.

[0227] Further, the curve regression module receives the borehole acoustic logging data of the formation acoustic travel time curve sound borehole sent by the data acquisition module, and according to the relational formula between the formation acoustic travel time and the formation depth and the formation triple lateral resistivity, regresses the formation acoustic travel time curve between the formation acoustic travel time and the formation depth and the formation triple lateral resistivity, including the following steps:

[0228] Taking the logarithm of both sides of Equation (6) and rearranging the terms, we obtain the following equation:

[0229]

[0230] Perform a substitution on Equation (7). Let:

[0231]

[0232] Substitute Equation (8) into Equation (7) to get:

[0233] y = b 0 + b 1 x 1 + b 2 x 2 (9)

[0234] Based on Equation (9), organize the relationship between the acoustic travel time curve of the rock formation, the acoustic travel time parameters of each rock layer in the borehole, the depth parameters of each rock layer, and the triple lateral resistivity parameters of each rock layer as follows:

[0235] y 1 = b 0 + b 1 x 11 + b 2 x 12

[0236] y 2 = b 0 + b 1 x 21 + b 2 x 22

[0237] y 3 = b 0 + b 1 x 31 + b 2 x 32

[0238] …………………………………………………………………

[0239] y i = b 0 + b 1 x i1 + b 2 x i2

[0240] Solve for b 0 , b 1 and b 2 ;

[0241] Substitute the solved \(b\) 0 , \(b\) 1 and \(b\) 2 into the relational expression (8) to solve for \(A\), \(N\), and \(M\); substitute \(A\), \(N\), and \(M\) into the relational expression (6) to complete the regression of the formation acoustic travel time curve between the formation acoustic travel time, the formation depth, and the formation triple lateral resistivity;

[0242] The formation acoustic travel time curve sound borehole is the formation acoustic travel time curve sound borehole that is the closest to the borehole lacking the formation acoustic travel time curve in the same working area and the same stratigraphic system.

[0243] Furthermore, the formation acoustic travel time logging data of the formation acoustic travel time curve sound borehole consists of \(n\) formation acoustic travel time logging data, and the \(i\)-th formation acoustic travel time logging data includes the following parameters: formation acoustic travel time (\(\Delta t\)) i , formation depth \(H\) i and formation triple lateral resistivity (\(R\) t ) i ;

[0244] \(x\) 1 =\(\{x\) 11 , \(x\) 21 , \(x\) 31 \(\cdots x\) i1 \}\), \(x\) i1 is calculated by the curve regression module based on the formation depth \(H\) of the formation acoustic travel time curve sound borehole i ;

[0245] \(x\) 2 =\(\{x\) 12 , \(x\) 22 , \(x\) 32 \(\cdots x\) i2 \}\), \(x\) i2 is calculated by the curve regression module based on the formation triple lateral resistivity depth (\(R\) t ) i ;

[0246] \(y = \{y\) 1 , \(y\) 2 , \(y\) 3 \(\cdots y\) i \}\), \(y\) i is calculated by the curve regression module based on the formation acoustic travel time (\(\Delta t\)) of the formation acoustic travel time curve sound borehole i ;

[0247] Furthermore, the curve regression module solves for \(b\) 0 , \(b\) 1 and \(b\) 2 through the formation acoustic travel time logging data of the formation acoustic travel time curve sound borehole, including the following steps:

[0248] Construct the following system of linear equations:

[0249] L 11 b 1 +L 12 b 2 =L 1y (10)

[0250] L 21 b 1 +L 22 b 2 =L 2y (11)

[0251] Wherein,

[0252]

[0253]

[0254] L 21 =L 12 (14)

[0255]

[0256]

[0257]

[0258]

[0259] Establish the following matrix to solve the above system of linear equations:

[0260]

[0261] Solve for b 0 、b 1 and b 2 。

[0262] Furthermore, the curve regression module evaluates the regression quality of the rock formation acoustic travel time regression curve between the rock formation acoustic travel time, the rock formation depth, and the rock formation triple lateral resistivity through the fitting degree. The calculation formula of the fitting degree is as follows:

[0263]

[0264]

[0265]

[0266] In the formula, Ass is the sum of the squares of the observed values of the acoustic travel time of each rock formation; Bss is the sum of the squares of the differences between the observed values and the regression values of the acoustic travel time of each rock formation; yi is the observed value of the acoustic travel time of the rock formation; is the regression value of the acoustic travel time of the rock formation; R 2 is the goodness of fit.

[0267] Further, the curve regression module establishes matrix (5) to solve the linear equations (9) and (10), and solves for b 0 , b 1 and b 2 , including the following steps:

[0268] Call Excel software and execute the following steps:

[0269] Store the parameters of the acoustic logging data of the sound borehole of the acoustic travel time curve of the rock formation in the Excel workbook by column respectively;

[0270] Calculate the acoustic travel time (△t) of each rock formation by solving the logarithmic function "log()" respectively i and the logarithm of the depth H of each rock formation i and store the calculated log(△t) i and logH i in the Excel workbook by column respectively;

[0271] Calculate L 11 , L 12 , L 21 , L 22 , L 1y and L 2y through the relational expressions (12)-(17), and store the calculated L 11 , L 12 , L 21 , L 22 , L 1y and L 2y in the matrices and in the Excel workbook by column respectively;

[0272] Solve the inverse matrix of matrix by solving the inverse matrix function "MINVERSE()", and solve the product of the inverse matrix of matrix and matrix by solving the matrix product function "MMULT()", and solve for b 1 and b 2 and store them in the Excel workbook;

[0273] Calculate b 0 according to the relational expression (18) and store it in the Excel workbook.

[0274] Further, the curve regression module calls Excel software and substitutes the solved b 0 , b 1 and b 2 into relation (8) to solve for A, N, and M; substitutes A, N, and M into relation (6) to complete the curve regression of the formation acoustic wave travel time between the formation acoustic wave travel time, formation depth, and formation triple lateral resistivity.

[0275] Further, the curve regression module calls Excel software and substitutes the calculated b 0 , b 1 and b 2 into relation (9) to solve for the regression value of the logarithm of the formation acoustic wave travel time and store it in columns in the Excel workbook;

[0276] solves for the regression value of the formation acoustic wave travel time by solving the antilogarithm function "Power()" and stores it in columns in the Excel workbook;

[0277] Calculates the square Ass of the observed values of the acoustic waves of each formation and the sum of squares Bss of the differences between the observed values and the regression values of the formation acoustic wave travel time according to relations (19)-(20);

[0278] Calculates the goodness of fit R 2 of the regression curve of the formation acoustic wave travel time according to relation (21).

[0279] Applies the method and system for constructing the borehole formation acoustic wave travel time curve of the present invention to the curve regression of the formation acoustic wave travel time curve of the sound borehole ZKn0-3 in the ×× area × basin of the in-situ leachable sandstone-type uranium deposit, and the goodness of fit R 2 of the regression formation acoustic wave travel time curve is 96.13%.

[0280] The regression curve of the formation acoustic wave travel time of borehole ZKn0-3 is:

[0281] △t = 1499.271 * H 0.09294 * 0.984 R t

[0282] where △t is the formation acoustic wave travel time, with the unit of μs / m; H is the formation depth, with the unit of m; R t is the formation triple lateral resistivity, with the unit of Ω·m.

[0283] See Figure 3 , comparing the regression curve of the formation acoustic wave travel time of the sound borehole ZKn0-3 in the ×× area × basin of the in-situ leachable sandstone-type uranium deposit with its measured formation acoustic wave travel time curve, it can be seen that:

[0284] 1. The measured acoustic wave travel time curve of the rock formation in borehole ZKn0-3 has no large fluctuations. From 130 to 443 meters, the curve is significantly skewed to the left; the regression curve of the acoustic wave travel time of the rock formation in borehole ZKn0-3 is significantly skewed to the left from 0 to 443 meters. The leftward skew of the acoustic wave travel time curve of the rock formation indicates that the acoustic wave propagation velocity of the rock formation gradually increases with the increase of the effective pressure of the overlying strata. The regression curve of the acoustic wave travel time of the rock formation in borehole ZKn0-3 is more sensitive to the effective pressure of the overlying strata than its measured acoustic wave travel time curve of the rock formation, and the measured rock formation density calculated therefrom is more accurate.

[0285] 2. The measured acoustic wave travel time curve of the rock formation in borehole ZKn0-3 does not reflect the differences in physical properties of the two major geological cycles, the Cretaceous and Jurassic, in the borehole profile; the regression curve of the acoustic wave travel time of the rock formation in borehole ZKn0-3 has a large difference in reflection for the conglomerate in the Cretaceous. At the conglomerate in the Cretaceous, the regression curve of the acoustic wave travel time of the rock formation in borehole ZKn0-3 and its triple lateral resistivity curve are in a mirror image relationship, clearly reflecting the interface between the two major geological cycles of the Cretaceous and Jurassic. The regression curve of the acoustic wave travel time of the rock formation in borehole ZKn0-3 can more accurately reflect the physical properties of the rock formation than its measured acoustic wave travel time curve of the rock formation.

[0286] Figure 3 In it, the obvious inclination of the borehole is caused by the magnification of the horizontal scale.

[0287] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, 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 appended claims.

Claims

1. A method for constructing the acoustic travel time curve of a drilled rock formation, characterized in that, it includes the following steps: Step 1: Establish a relationship between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation; Step 2: Substitute the relationship between the acoustic wave propagation velocity of the rock formation and the acoustic travel time of the rock formation into the relationship in Step 1, and after arrangement, obtain the relationship between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation; Step 3: Based on the acoustic travel time curve of the drilled rock formation, improve the acoustic logging data of the drilled rock formation and regress the acoustic travel time curve between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation; Step 4: Use the acoustic travel time regression curve in Step 3 as the acoustic travel time regression curve of the drilled hole with missing acoustic travel time curve, extract the parameters necessary for calculating the acoustic travel time of the rock formation from the acoustic logging data of the drilled hole with missing acoustic travel time curve, and substitute them into the acoustic travel time regression curve to calculate the acoustic travel time parameters of the drilled hole with missing acoustic travel time curve.

2. The method for constructing the acoustic travel time curve of a drilled rock formation according to claim 1, characterized in that, in Step 1, the relationship between the acoustic wave propagation velocity of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation is: Wherein, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; H is the depth of the rock formation, with the unit of m; R t is the triple lateral resistivity of the rock formation, with the unit of Ω·m; M is the formation factor of the area; A and N are undetermined parameters.

3. The method for constructing the acoustic travel time curve of a drilled rock formation according to claim 2, characterized in that, in Step 2, the relationship between the acoustic wave propagation velocity of the rock formation and the acoustic travel time of the rock formation is as follows: Substitute relationship (3) into the relationship in Step 1 to obtain the following relationship: After arranging relationship (5), obtain the statistical relationship between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation: In the formula, V is the acoustic wave propagation velocity of the rock formation, with the unit of m / s; Δt is the acoustic wave time difference of the rock formation, with the unit of μs / m; H is the depth of the rock formation, with the unit of m; R t is the triple lateral resistivity of the rock formation, with the unit of Ω·m; M is the formation factor of the area; A and N are undetermined parameters.

4. The method for constructing the acoustic travel time curve of a drilled rock formation according to claim 3, characterized in that, Step 3, based on the acoustic travel time curve of the drilled rock formation, improve the acoustic logging data of the drilled rock formation and regress the acoustic travel time curve between the acoustic travel time of the rock formation, the depth of the rock formation, and the triple lateral resistivity of the rock formation, including the following steps: Step 3.1: Take the logarithm of both sides of relationship (6) and transpose and arrange to obtain the following relationship: Step 3.2: Perform a substitution on relationship (7), let: Step 3.3: Substitute relationship (8) into relationship (7) to obtain: y = b 0 + b 1 x 1 + b 2 x 2 (9) Step 3.4: Based on relationship (9), arrange the relationship between the acoustic travel time parameters of each rock formation, the depth parameters of each rock formation, and the triple lateral resistivity parameters of each rock formation in the drilled hole with improved acoustic travel time curve 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: Solve b for the borehole's formation acoustic logging data by using the formation acoustic travel time curve 0 , b 1 and b 2 ; Step 3.6: Substitute the solved \(b_{ 0}\), \(b_{ 1}\), and \(b_{ 2}\) into Equation (8) to solve for \(A\), \(N\), and \(M\); then substitute \(A\), \(N\), and \(M\) into Equation (6) to complete the regression of the formation acoustic travel time curve between the formation acoustic travel time, formation depth, and formation triple lateral resistivity. 0 and \(b_{ 1}\) 1 and \(b_{ 2}\) 2 into Equation (8) to solve for \(A\), \(N\), and \(M\); then substitute \(A\), \(N\), and \(M\) into Equation (6) to complete the regression of the formation acoustic travel time curve between the formation acoustic travel time, formation depth, and formation triple lateral resistivity. The drilled hole with improved acoustic travel time curve is the drilled hole with the acoustic travel time curve of the rock formation closest to the drilled hole with missing acoustic travel time curve in the same working area and the same stratigraphic system.

5. The method for constructing the acoustic travel time curve of a drilled rock formation according to claim 4, characterized in that, The acoustic wave travel time curve of the rock formation. The acoustic wave logging data of the sound borehole of the rock formation consists of n acoustic wave logging data of the rock formation. The i-th acoustic wave logging data of the rock formation includes the following parameters: acoustic wave travel time of the rock formation (Δt) i , formation depth Hi, and formation triple lateral resistivity (R t ) i ; x 1 = {x 11 , x 21 , x 31 ... x i1}, x i1 is calculated based on the sonic transit time curve of the rock formation to improve the borehole rock formation depth H i ; x 2 = {x 12 , x 22 , x 32 ... x i2}, x i2 is calculated based on the acoustic travel-time curve of the rock formation to improve the three-lateral resistivity depth (R t ) i of the borehole rock formation; y = {y 1 , y 2 , y 3 ... y i}, y i is calculated based on the sonic transit time curve of the rock formation to improve the sonic transit time (Δt) of the borehole rock formation i .

6. The method for constructing the acoustic travel time curve of a drilled rock formation according to claim 5, characterized in that, Step 3.5, solve b for the borehole's formation acoustic logging data by improving the formation acoustic travel-time curve 0 , b 1 and b 2 , including the following steps: Step 3.5.1: Establish the following linear equations: L 11 b 1 +L 1 2b 2 =L 1y (10) L 21 b 1 +L 22 b 2 =L 2y (11) where, L 21 = L 12 (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 the acoustic travel time curve of a drilled rock formation according to claim 6, characterized in that, The regression quality of the regression curve of the formation acoustic wave travel time between the formation acoustic wave travel time and the formation depth and the formation triple lateral resistivity is evaluated by the goodness of fit. The calculation formula of the goodness of fit is as follows: Where Ass is the sum of squares of the observed values of the acoustic wave travel times of each rock stratum; Bss is the sum of squares of the differences between the observed values and the regression values of the acoustic wave travel times of each rock stratum; y i is the observed value of the acoustic wave travel time of the rock stratum; is the regression value of the acoustic wave travel time of the rock stratum; R 2 is the goodness of fit.

8. The method for constructing the borehole formation acoustic wave travel time curve according to claim 6, wherein, Step 3.5.2, establish matrix (5) to solve linear equations (9) and (10), and solve for b 0 , b 1 and b 2 , including the following steps: in Excel software, the following steps are executed: Store each parameter of the formation acoustic wave logging data of the borehole with a sound formation acoustic wave travel time curve in columns in an Excel workbook; Calculate the acoustic wave time difference (Δt) of each rock stratum by solving the logarithmic function "log()" respectively i and the depth H of each rock stratum i Take the logarithm and store the calculated log(Δt) i and logH i in columns in the Excel workbook respectively; Calculate L respectively through relational expressions (12)-(17) 11 、L 12 、L 21 、L 22 、L 1y and L 2y , and store the calculated L 11 、L 12 、L 21 、L 22 、L 1y and L 2y in the Excel workbook respectively according to matrices and ; The inverse matrix of the matrix is solved by solving the inverse matrix function "MINVERSE()". The inverse matrix of the matrix is solved by solving the matrix product function "MMULT()". The product of the inverse matrix of the matrix and the matrix is solved to obtain b 1 and b 2 and stored in the Excel workbook. Calculate b according to relation (18). 0 And store it in the Excel workbook.

9. The method for constructing the borehole formation acoustic wave travel time curve according to claim 8, wherein, Step 3.6, in Excel software, substitute the solved b 0 , b 1 and b 2 into relation formula (8) to solve for A, N, and M; substitute A, N, and M into relation formula (6) to complete the regression of the formation acoustic travel time curve between the formation acoustic travel time, formation depth, and formation triple lateral resistivity.

10. The method for constructing the borehole formation acoustic wave travel time curve according to claim 9, wherein, In the Excel software, substitute the calculated b 0 , b 1 and b 2 into the relational expression (9), solve for the regression value of the logarithm of the acoustic travel time of the rock formation, and store it column by column in the Excel workbook; Solve the formation acoustic wave travel time regression value by solving the antilogarithm function "Power()" and store it in columns in the Excel workbook; Calculate the square Ass of each formation acoustic wave observation value and the sum of squares Bss of the differences between each formation acoustic wave travel time observation value and the regression value according to the relational expressions (19)-(20); Calculate the fitting degree R of the regression curve of the acoustic travel time of the rock formation according to the relational expression (21). 2 .

11. The method for constructing the borehole formation acoustic wave travel time curve according to any one of claims 1-10, wherein, In step 4, the borehole acoustic logging data of the missing formation acoustic time difference curve borehole includes the following parameters: formation depth H and formation triple lateral resistivity R t .

12. A system for constructing a borehole formation acoustic wave travel time curve, wherein, comprising: A data acquisition module for acquiring the formation acoustic wave logging data of the borehole with a sound formation acoustic wave travel time curve and the formation acoustic wave logging data of the borehole without a formation acoustic wave travel time curve, and sending the formation acoustic wave logging data of the borehole with a sound formation acoustic wave travel time curve to the curve regression module and sending the formation acoustic wave logging data of the borehole without a formation acoustic wave travel time curve to the parameter calculation module; A curve regression module for receiving the formation acoustic wave logging data of the borehole with a sound formation acoustic wave travel time curve sent by the data acquisition module, and regressing the formation acoustic wave travel time curve between the formation acoustic wave travel time and the formation depth and the formation triple lateral resistivity according to the relational expressions between the formation acoustic wave travel time and the formation depth and the formation triple lateral resistivity and sending it to the parameter calculation module; A parameter calculation module for receiving the formation acoustic wave logging data of the borehole without a formation acoustic wave travel time curve sent by the data acquisition module and the formation acoustic wave travel time regression curve sent by the curve regression module, extracting the parameters necessary for calculating the formation acoustic wave travel time from the formation acoustic wave logging data of the borehole without a formation acoustic wave travel time curve and substituting them into the formation acoustic wave travel time regression curve to calculate the formation acoustic wave travel time parameters of the borehole without a formation acoustic wave travel time curve.

Images