Method and system for establishing well-seismic relationship of whole well section based on drilling index Dx

Abstract

The application discloses a method and system for establishing well-seismic relationship of a whole well section based on drilling index Dx, and proposes to use the commonality that both the formation acoustic velocity and the drilling index Dx reflect the change of the regional formation compaction trend with depth, to construct a comprehensive parameter that the power index of the product of the acoustic velocity and the drilling index Dx changes with depth, to obtain an empirical formula of the burial depth of the formation, the drilling index Dx and the acoustic velocity through regression analysis, and to calculate the acoustic velocity and the time-depth relationship fitted by the drilling index Dx with the burial depth of the formation; based on the acoustic velocity fitted by the drilling index Dx and the Gardner formula, the wave impedance and the reflection coefficient are calculated, the reflection coefficient is deconvoluted with the selected wavelet to generate a synthetic seismic record. The method and system can realize the well-seismic calibration of the whole well section with the drilling parameters as the data source in the case that there is no or insufficient logging acoustic velocity and density data.

Description

Technical Field

[0001] This invention relates to the fields of well logging and geology, and in particular to a method and system for establishing well-seismic relationships across the entire well section based on the drilling index Dx. Background Technology

[0002] Synthetic seismic records are seismic records (seismic traces) artificially synthesized from sonic logging or vertical seismic profile data. They are usually seismic trace models generated by well logging or vertical seismic logging (VSP) and seismic wavelet convolution. By establishing a time-depth relationship, geological information obtained along the wellbore is correlated with regional seismic information, laying the foundation for the comprehensive interpretation of seismic data and the prediction of the distribution of geological sedimentary bodies on the plane.

[0003] The general workflow for creating synthetic seismic records is as follows: Reflection coefficients are calculated from acoustic and density logging curves. These reflection coefficients are then convolved with extracted seismic wavelets to obtain an initial synthetic seismic record. The initial synthetic seismic record is corrected based on a more accurate velocity field, and then matched and adjusted with the well-side seismic traces to finally obtain the synthetic seismic record. In summary, the process involves: extracting rock density and velocity information at a selected well location from logging data; calculating rock wave impedance based on density and velocity data to obtain a reflection coefficient sequence; selecting parameters such as wavelet type, dominant frequency, and sampling rate to determine a suitable seismic wavelet; and convolving the seismic wavelet with the reflection coefficient sequence to obtain the synthetic seismic record.

[0004] In regional geological research using post-drilling geological information, combining well and seismic data is an essential method. For wells without sonic or VSP seismic logging data, the existing time-depth relationship of neighboring wells is usually directly applied to this well; or other types of logging data from this well, such as resistivity data, are used to simulate sonic data, and then the time-depth relationship of this well is artificially constructed.

[0005] Due to limitations in geophysical logging technology, logging costs, and complex downhole geological conditions, only a limited number of wells can be selected for sonic or VSP seismic logging during or after drilling. Furthermore, even when formation sonic logging is implemented, the measurement interval is often limited to the target formation. These limitations hinder the establishment of well-seismic time-depth relationships in many drilled wells due to a lack of sonic or VSP logging data, preventing the achievement of full-section well-seismic calibration. Even when parameters such as logging resistivity are used to fit sonic logging data, the limitations still arise from factors such as the appropriateness of the logging interval and the suitability of the parameters. Summary of the Invention

[0006] The technical problem to be solved by this invention is to construct a quantitative formula for fitting the sonic velocity with the drilling index Dx for wells or well sections without sonic logging data, and to apply it to establish time-depth relationships and produce synthetic seismic records.

[0007] To address the aforementioned technical problems, this invention provides a well-seismic calibration method that utilizes the drilling index Dx to synthesize seismic records and calculate the time-depth relationship.

[0008] This invention can be achieved through the following technical solution: a method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx, comprising the following steps:

[0009] Step S1: Obtain drilling machine speed, total drill bit speed, drilling pressure and drill bit size during the drilling process using drilling parameters as the data source, and calculate the dimensionless parameter drilling index Dx that indicates the strength of the rock skeleton;

[0010] Step S2: Acquire data from the well section of the project with acoustic velocity and density logging, create a synthetic seismic record based on the logging data, determine the travel time of each stratum layer point on the seismic profile through well-seismic calibration, and obtain the time-depth relationship curve calculated based on the logging data through regression.

[0011] Step S3: Select well sections with logging acoustic data, construct a comprehensive parameter that shows the power exponent of the product of logging acoustic velocity and drilling index Dx as it increases with depth, and obtain the relationship between the formation burial depth and drilling index Dx and logging acoustic velocity through regression analysis.

[0012] Step S4: Connect the relationship between the formation burial depth and drilling index Dx and sonic velocity obtained from the regression analysis with the comprehensive index relationship constructed from the logging sonic velocity, drilling index Dx and depth. Treat the sonic velocity DT in the relationship as an unknown quantity to obtain the relationship between the drilling index Dx and the sonic velocity Dx_Sim.

[0013] Step S5: Based on the acoustic velocity Dx_Sim calculated from the drilling index Dx, calculate the time-depth relationship. Substitute the acoustic velocity Dx_Sim fitted by the drilling index Dx into Gardner's empirical formula to calculate the rock density Dx_den. Substitute the acoustic velocity Dx_Sim fitted by Dx and the rock density Dx_den into the wave impedance calculation formula to obtain the wave impedance value Dx_AI. Calculate the reflection coefficient according to the set sampling interval. Select a suitable wavelet and perform deconvolution calculation of the reflection coefficient and the wavelet product to obtain the synthetic seismic record based on the drilling index Dx.

[0014] Step S6: Calculate the fitted sonic velocity Dx_Sim from the drilling index Dx of the entire well section, and calculate the rock density using Gardner's empirical formula. Finally, obtain the wave impedance Dx_AI of the entire well section based on the drilling index Dx, and complete the production of the synthetic seismic record of the entire well section.

[0015] Furthermore, step S3 also includes a step of comparing the time-depth relationship of the sonic velocity fitted by the drilling index Dx, specifically as follows: taking the well depth where the logging sonic velocity point begins as the starting point for comparison, converting the sonic velocity fitted by the logging and drilling index Dx into time per unit depth, calculating the cumulative time required as the depth increases, comparing the travel time of geological strata on the seismic profile with the time-depth relationship obtained by the logging and drilling index Dx fitted sonic velocity, and checking the differences between the seismic travel time of each stratum and the time-depth relationship calculated by the drilling and logging.

[0016] Furthermore, step S1 also includes: if different wellbore sections or different types of drill bits cause discontinuous segments in the drilling index Dx data, it is necessary to perform overall translation or addition / subtraction preprocessing on the data, and smooth out points with obvious ambiguity.

[0017] Furthermore, the synthetic seismic record obtained from the well logging sonic calibration in step S2 is compared with the drilling index Dx, and the actual drilling index Dx result is made similar to or consistent with the well logging seismic calibration result by segmenting and correcting the drilling index Dx.

[0018] The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 1 is characterized in that the formula for calculating the comprehensive parameter of the power exponent of the product of the logging sonic velocity and the drilling index Dx increasing with depth in step S3 is as follows:

[0019] DT_Dx = (Depth) 1 / 6 ×(DT×Dx) 1 / 60 ;

[0020] In the formula: DT is the acoustic velocity, Dx is the drilling exponent, and Depth is the well depth.

[0021] Furthermore, the formula for the relationship between the drilling index Dx and the comprehensive index constructed from the depth mentioned in step S4 is as follows:

[0022]

[0023] In the formula, DT_Dx is considered as DT_Dx_Trend, and DT is the sound wave Dx_Sim to be fitted.

[0024] (Depth) 1 / 6 ×(Dx_Sim×Dx) 1 / 60 = 1.0497 × (Depth) 0.169972 ,

[0025] The acoustic wave relationship fitted by the Dx exponent and depth is as follows:

[0026] Dx_Sim = (1.0497) 60 ×(Depth) 0.19833 / Dx;

[0027] In the formula: Dx_Sim is the acoustic velocity fitted by the drilling index Dx; Depth is the well depth.

[0028] Furthermore, the formula for calculating rock density is as follows:

[0029] Dx_den=0.31×((1 / Dx_Sim)×(1000000 / 3.28)) 0.25 ;

[0030] In the formula: Dx_Sim is the acoustic velocity (us / ft) fitted to the drilling index Dx.

[0031] Furthermore, using the wave impedance calculation formula, the wave impedance Dx_AI is calculated by fitting the acoustic wave Dx_Sim and density Dx_den to the drilling index Dx:

[0032] Dx_AI=Dx_den×(1 / Dx_Sim)×(1000000 / 3.28);

[0033] In the formula: Dx_den is the rock density calculated from the acoustic velocity fitted by the drilling index Dx;

[0034] Dx_Sim is the acoustic velocity (µs / ft) fitted to the drilling index Dx.

[0035] Another technical solution is: a system for establishing the well-seismic relationship across the entire well section based on the drilling index Dx, characterized by comprising the following modules:

[0036] Drilling index Dx calculation and processing module: Obtains drilling machine speed, total drill bit speed, drilling pressure and drill bit size during the drilling process, and calculates the dimensionless parameter Dx, which indicates the strength of the rock skeleton, using the formula;

[0037] Well logging data well seismic calibration module for establishing time-depth relationship: acquire data of well sections with acoustic velocity and density logging projects, produce synthetic seismic records based on well logging data, determine the travel time of each stratum layer point on the seismic profile through well seismic calibration, and obtain the time-depth relationship curve calculated based on well logging data through regression;

[0038] Well logging sonic wave and drilling index Dx trend line fitting module: Select well sections with well logging sonic wave data, construct a comprehensive parameter that shows the power exponent of the product of sonic wave velocity and drilling index Dx increases with depth, and perform regression analysis on this comprehensive parameter to obtain the relationship between the power exponent of the product of sonic wave velocity and Dx and depth;

[0039] The module for fitting sonic velocity and correction to the drilling index Dx: By connecting the regression formula of the relationship between the power exponent of the product of sonic velocity and Dx and depth with the constructed comprehensive index formula of logging sonic velocity, drilling index Dx and depth, and substituting the sonic velocity DT as the dependent variable, the sonic velocity Dx_Sim fitted as the drilling index Dx changes is obtained.

[0040] The drilling index Dx synthetic seismic record module: Based on the time-depth relationship determined by fitting the acoustic wave with the drilling index Dx, Dx_den is calculated using the acoustic velocity Dx_Sim fitted by the drilling index Dx and the Gardner rock density empirical formula. The acoustic wave impedance Dx_AI fitted by the drilling index Dx is calculated using the wave impedance calculation formula. The reflection coefficient is calculated according to the set sampling interval, and a suitable wavelet is selected to perform deconvolution calculation of the product of the reflection coefficient and the wavelet to obtain the synthetic seismic record based on the drilling index Dx.

[0041] The module for creating synthetic seismic records for the entire well section using the drilling index Dx is as follows: The fitted sonic velocity Dx_Sim for the entire well section is calculated using the relationship between the drilling index Dx and the sonic velocity Dx_Sim. Then, Dx_den for the entire well section is calculated using Gardner's empirical formula for rock density. Finally, the wave impedance Dx_AI for the entire well section based on the drilling index Dx is obtained using the wave impedance calculation formula, and the creation of the synthetic seismic record for the entire well section is completed.

[0042] Furthermore, it also includes: a module for comparing the time-depth relationship of sonic velocity fitted by the drilling index Dx: taking the well depth with logging sonic velocity as the initial point of calculation, converting the sonic velocity fitted by the logging and drilling index Dx into time per unit depth, accumulating the time required with depth, comparing the travel time of seismic geological stratification with the time-depth relationship obtained by the logging and drilling index Dx fitted, and checking the differences between the synthetic seismic records made by drilling and logging.

[0043] The technical advantages of this invention are as follows: This invention is a method and system for establishing well-seismic relationships throughout the entire well section based on the drilling index Dx. Since the drilling index Dx is a parameter that can be obtained in real time from the start of drilling operations to the completion of drilling, using this parameter to fit acoustic velocity and create synthetic seismic records can compensate for the inability to perform timely and accurate well-seismic tracking during drilling due to the lack of logging acoustic velocity data.

[0044] This invention uses the drilling index Dx to fit the sonic waveform to create a synthetic seismic record for the entire well section, which makes up for the lack of electrical logging data in the upper formations, which prevents the creation of synthetic seismic records. This results in a real-time well seismic calibration that does not rely on logging methods. Attached Figure Description

[0045] Figure 1 This is the segmented correction diagram of the drilling index Dx of this invention;

[0046] Figure 2 This is a depth-time relationship diagram of well logging acoustic waves and density-synthesized seismic records calibrated according to the present invention;

[0047] Figure 3 This invention provides a well logging acoustic wave and density-synthesized seismic record diagram.

[0048] Figure 4 This is a trend fitting diagram of the relationship between logging acoustic velocity, drilling index Dx and depth according to the present invention;

[0049] Figure 5 This is a comparison chart of the acoustic velocity fitting between the logging acoustic velocity and the drilling index Dx according to the present invention;

[0050] Figure 6 This is a time-depth relationship diagram of the well logging acoustic velocity synthesis seismic record according to the present invention;

[0051] Figure 7 This invention relates to a time-depth relationship diagram of seismic records synthesized by fitting the drilling index Dx with acoustic velocity.

[0052] Figure 8 This invention relates to a seismic record graph composed of acoustic and density composites based on the drilling index Dx.

[0053] Figure 9 This is a comparison diagram of the well logging and drilling index Dx fitting acoustic and density-synthesized seismic records of the present invention;

[0054] Figure 10 This is a graph showing the time-depth variation of fitted sonic velocity before and after correction of the drilling index Dx for the entire well section according to the present invention;

[0055] Figure 11 This is a composite seismic record of the drilling index Dx for the entire well section, as described in this invention.

[0056] Figure 12 This is a flowchart of the method for establishing the well-seismic relationship of the entire well section based on the drilling index Dx, as described in claim 6 of the present invention. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0058] The drilling index Dx, also known as the d-exponent, is a dimensionless parameter calculated using an empirical formula based on data collected during the drilling process, including drilling rate (ROP), bit weight on the drill bit (WOB), bit rotation speed (RPM), and bit size. This parameter reflects the drillability of the formation, and its value indicates the strength of the rock skeleton.

[0059] like Figures 1-12 The present invention relates to a method and system for establishing the well-seismic relationship of the entire well section based on the drilling index Dx, and includes the following modules and steps.

[0060] 1. Drilling Index (Dx) Calculation and Processing Module

[0061] Using empirical formulas reflecting formation drillability, dimensionless parameters indicating rock skeleton strength are calculated. The drilling parameters used are unit drilling rate (ROP), bottom hole bit rotation speed (RPM), weight on bit (WOB), and bit size. The formula expression is as follows:

[0062]

[0063] ROP: Drilling speed (m / hr);

[0064] RPM: Total rotational speed of the drill bit (1 / min);

[0065] WOB: Drilling pressure (klbm);

[0066] BIT: Drill bit size (In).

[0067] Table 1 shows the experimental data, which is a list of values ​​for calculating the drilling index Dx of XX well.

[0068]

[0069] Table 1

[0070] like Figure 1 As shown in the example, due to the discontinuity of data segments caused by different wellbore sections or different types of drill bits, it is necessary to perform preprocessing such as overall translation or addition / subtraction of the data, and to smooth out points with obvious ambiguity.

[0071] As the drilling pressure recorded during the drilling process of the 17.5” wellbore size continued to increase, the drilling index Dx differed from that of the subsequent 12.25” wellbore. Correction was performed to ensure that the data for different wellbore sizes were consistent.

[0072] 2. Well logging data seismic calibration module for establishing time-depth relationship

[0073] Table 2 shows the results of well logging acoustic wave and density synthesis seismic calibration based on the experimental data. Figure 2 This invention relates to a time-depth relationship diagram for well logging acoustic and density-synthesized seismic records. It uses well logging acoustic velocity and density data to synthesize seismic records. Well and seismic calibration determines the seismic travel time of each stratum layer point on the seismic profile, and the time-depth relationship curve is obtained through regression. Figure 3 This is a well logging acoustic and density-synthesized seismic record.

[0074]

[0075] Table 2

[0076] 3. Well logging acoustic wave and drilling index Dx trend line fitting module

[0077] Selecting well sections with logging sonic data, and referring to the Fast formula, a comprehensive parameter is constructed for the power exponent of the product of sonic velocity and drilling exponent Dx as it increases with depth. The formula for calculating DT_Dx is as follows:

[0078] DT_Dx = (Depth) 1 / 6 ×(DT×Dx) 1 / 60

[0079] in:

[0080] DT: Speed ​​of sound (µs / ft)

[0081] Dx: Drilling Index (unitless)

[0082] Depth: Well depth (m)

[0083] Table 3 shows the experimental data, which is a table of calculated results for logging acoustic velocity, drilling index Dx, and well depth.

[0084] well deep TVDss speed of sound Dx Index DT_Dx results 1110 1087 113.05 0.6231 3.4542 1111 1088 107.66 0.5973 3.4495 1112 1089 102.19 0.6551 3.4523 1113 1090 97.77 0.6616 3.4509 1114 1091 107.45 0.6640 3.4570 1115 1092 105.50 0.6904 3.4587 1116 1093 130.45 0.7587 3.4770 1117 1094 114.84 0.8576 3.4772 1118 1095 113.32 0.9067 3.4802 1119 1096 114.78 0.9593 3.4847 1120 1097 108.82 0.8167 3.4728

[0085] Table 3

[0086] The relationship between this parameter and depth was obtained through regression as follows: Figure 4 As shown.

[0087] The regression analysis of the relationship between the constructed comprehensive parameters and depth showed a correlation of 0.9985, indicating a high correlation between the trends of logging sonic velocity and drilling exponent Dx with depth. The expression for their relationship with depth is as follows:

[0088] DT_Dx_Tren = 1.05 × (Depth) 0.1699

[0089] Due to the limited precision in the above formula, the final expression is:

[0090] DT_Dx_Tren = 1.0497 × (Depth) 0.169972

[0091] In the formula:

[0092] DT_Dx_Tren: Regression trend line of the composite index of sound velocity, Dx, and depth (unitless)

[0093] Depth: Well depth (m)

[0094] 4. Drilling index Dx fitting acoustic velocity and correction module

[0095] The regression formula relating the power exponent of the product of acoustic velocity and Dx to depth is combined with the constructed comprehensive exponential formula for logging acoustic velocity, drilling exponent Dx, and depth. Using the acoustic velocity DT in the formula as the dependent variable, the acoustic velocity Dx_Sim relationship fitted to the changes in drilling exponent Dx and depth is obtained:

[0096]

[0097] In the formula, DT_Dx is considered as DT_Dx_Tren, and DT is the sound wave Dx_Sim to be fitted.

[0098] (Depth) 1 / 6 ×(Dx_Sim×Dx) 1 / 60 = 1.0497 × (Depth) 0.169972

[0099] The acoustic velocity Dx_Sim, fitted by the drilling exponent Dx as a function of depth, is obtained as follows:

[0100] Dx_Sim = (1.0497) 60 ×(Depth) 0.19833 / Dx

[0101] In the formula:

[0102] Dx_Sim: Fitted sonic velocity (µs / ft) as a function of drilling exponent Dx and well depth.

[0103] Depth: Well depth (m)

[0104] The results of the acoustic velocity calculation fitted to the drilling index Dx are shown in Table 4 below:

[0105] well deep TVDss DT sound wave speed Dx Index Dx_Sim results 1110 1087 113.05 0.6231 118.3869 1111 1088 107.66 0.5973 123.5346 1112 1089 102.19 0.6551 112.6512 1113 1090 97.77 0.6616 111.5715 1114 1091 107.45 0.6640 111.1811 1115 1092 105.50 0.6904 106.9414 1116 1093 130.45 0.7587 97.3357 1117 1094 114.84 0.8576 86.1273 1118 1095 113.32 0.9067 81.4812 1119 1096 114.78 0.9593 77.0222 1120 1097 108.82 0.8167 90.4901

[0106] Table 4 presents the statistical results of the well logging and Dx-fitted acoustic velocity data, as shown in Table 5 below:

[0107]

[0108] Table 5

[0109] Statistical results show that the maximum and minimum variations of the acoustic velocity fitted by the drilling index Dx are larger than those of the well logging results, but the difference in the average value is relatively small.

[0110] like Figure 5As shown, this is a comparison of the acoustic velocity from well logging and the acoustic velocity fitted by the drilling index Dx. The overlay plot of the two data sources shows that the acoustic velocity fitted by Dx and the acoustic velocity from well logging have a high degree of similarity. To maintain the accuracy of the acoustic data fitted by the drilling index Dx as much as possible, no smoothing or filtering was performed on the Dx data in this calculation.

[0111] 5. Comparison module for fitting the time-depth relationship of sonic velocity to the drilling index Dx

[0112] Using the well depth with logging sonic velocity as the initial point for calculation, the sonic velocities fitted by the logging and drilling index Dx are converted into time per unit depth (time required per 1 meter in this example), and the time required with depth is accumulated. Considering that the well depth measurement systems used for logging and drilling are different, there is a problem of well depth consistency between the two. In this example, the main target layer of EP210 is selected as the reference surface for the accumulated time. The travel time of the seismic geological strata is compared with the time-depth relationship obtained from the sonic velocities fitted by the logging and drilling index Dx to check the differences between the synthetic seismic records made by drilling and logging. Table 6 is a comparison table of accumulated time of logging and Dx-fitted sonic velocities and seismic travel time.

[0113]

[0114] Table 6

[0115] in, Figure 6 To synthesize the time-depth relationship diagram of the seismic record from well logging acoustic velocity, Figure 7 The time-depth relationship of acoustic velocity in synthetic seismic records is fitted to the drilling index Dx. The regression curve and correlation coefficient of the fitted acoustic velocity-time-depth relationship are shown; the two formulas differ only slightly.

[0116] Depend on Figure 6 Well logging and Figure 7 The comparison results of the time-depth relationship diagram of the sonic velocity fitted by the drilling index Dx show that the time-depth relationship of the sonic velocity fitted by the drilling index Dx can also reflect the propagation law of P-waves in rocks with different wave impedances. At the same time, the statistical results show that the time-depth relationship of the sonic velocity fitted by the drilling index Dx is closer to the travel time of seismic geological stratification.

[0117] 6. Drilling Index Dx Synthetic Seismic Record Module

[0118] Based on the time-depth relationship determined by fitting the acoustic wave with the drilling index Dx, the acoustic velocity fitted by the drilling index Dx and the rock density derived from the Gardner formula are used to calculate the wave impedance. The reflection coefficient is calculated at a certain sampling interval (usually 2 ms). A suitable wavelet (usually a 30Hz Ricker wavelet, 128 ms in length, and zero phase) is selected, and the deconvolution of the reflection coefficient and the wavelet product is performed to obtain the following result: Figure 8As shown, the fitted acoustic and density-synthesized seismic records are based on the drilling index Dx.

[0119] Gardner's formula for calculating rock density:

[0120] Dx_den=0.31×((1 / Dx_Sim)×(1000000 / 3.28)) 0.25

[0121] In the formula:

[0122] Dx_Sim: The acoustic velocity (µs / ft) fitted by the drilling exponent Dx.

[0123] The formula for calculating the acoustic impedance fitted to the drilling index Dx is as follows:

[0124] Dx_AI=Dx_den×(1 / Dx_Sim)×(1000000 / 3.28)

[0125] In the formula:

[0126] Dx_Sim: The acoustic velocity (µs / ft) fitted by the drilling exponent Dx.

[0127] The formula for calculating the acoustic reflection coefficient fitted to the drilling index Dx is as follows:

[0128] Dx_Re (i+1) =(Dx_AI) (i+1) -Dx_AI (i) ) / (Dx_AI (i+1) +Dx_AI (i) i = 1, 2, ..., n

[0129] In the formula:

[0130] Dx_Re (i+1) : Reflection coefficient at well depth i+1.

[0131] The formula for calculating synthetic seismic records is:

[0132] S(t)=R(t)×W(t)

[0133] In the formula:

[0134] S(t): Synthetic seismic record;

[0135] R(t): Reflection coefficient sequence (Dx_Re in this example):

[0136] W(t): Seismic wavelet (in this example, the 30Hz Ricker wavelet is selected).

[0137] Figure 9To compare the results of synthetic seismic records made by fitting the acoustic, density, and time-depth relationships of well logging data with the drilling index Dx, respectively.

[0138] Comparative analysis of synthetic seismic records produced from two data sources showed a high degree of similarity, indicating that the drilling index Dx can also be used to synthesize seismic records. It possesses real-time capabilities that well logging lacks and can achieve well-seismic comparison and tracking across the entire well section.

[0139] 7. Module for generating synthetic seismic records from the drilling index Dx of the entire well section.

[0140] The drilling index Dx is data available from the start of drilling to completion. As mentioned earlier, the drilling index Dx may need to be corrected due to different wellbore sizes or the use of different types of drill bits. Figure 10 The figure shows the relationship between the changes in the drilling index Dx before and after correction and the fitting acoustic time-depth diagram of the drilling index Dx.

[0141] In this embodiment, after correcting the drilling index Dx for a 17.5” wellbore size, the time-depth relationship shifted overall. Table 7 shows the statistical results of the changes in the time-depth relationship before and after the drilling index Dx correction.

[0142]

[0143] Table 7

[0144] The density was calculated using Gardner's empirical formula, and the whole-well acoustic waveform was fitted with the drilling index Dx. Finally, the wave impedance based on the drilling index Dx was calculated, and the synthetic seismic record of the whole well section was completed.

[0145] Figure 11 The synthetic seismic record made by fitting the sonic waves with the drilling index Dx for the entire well section makes up for the lack of synthetic seismic record production in the upper formation due to the absence of electrical logging data, and realizes real-time well seismic calibration of the entire well section without relying on logging.

[0146] Figures 1-10 The diagram illustrates the relationship between these parameters. The specific values ​​in the diagram change continuously based on actual seismic horizons, lithology, well depth, vertical depth, and drilling index Dx. This data is within the scope of protection of this application; the curves in the diagram merely represent the changing trends.

[0147] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0148] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process and related descriptions of the storage device and processing device described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0149] Those skilled in the art will recognize that the modules and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. The programs corresponding to the software modules and method steps can be placed in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. To clearly illustrate the interchangeability of electronic hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the invention.

[0150] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0151] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx, characterized in that, Includes the following steps: Step S1: Obtain drilling machine speed, total drill bit speed, drilling pressure and drill bit size during the drilling process using drilling parameters as the data source, and calculate the dimensionless parameter drilling index Dx that indicates the strength of the rock skeleton; Step S2: Acquire data from the well section of the project with acoustic velocity and density logging, create a synthetic seismic record based on the logging data, determine the travel time of each stratum layer point on the seismic profile through well-seismic calibration, and obtain the time-depth relationship curve calculated based on the logging data through regression. Step S3: Select well sections with logging acoustic data, construct a comprehensive parameter that shows the power exponent of the product of logging acoustic velocity and drilling index Dx as it increases with depth, and obtain the relationship between the formation burial depth and drilling index Dx and logging acoustic velocity through regression analysis. Step S4: Connect the relationship between the formation burial depth and drilling index Dx and sonic velocity obtained from the regression analysis with the comprehensive index relationship constructed from the logging sonic velocity, drilling index Dx and depth. Treat the sonic velocity DT in the relationship as an unknown quantity to obtain the relationship between the drilling index Dx and the sonic velocity Dx_Sim. Step S5: Based on the acoustic velocity Dx_Sim calculated from the drilling index Dx, calculate the time-depth relationship. Substitute the acoustic velocity Dx_Sim fitted by the drilling index Dx into Gardner's empirical formula to calculate the rock density Dx_den. Substitute the acoustic velocity Dx_Sim fitted by Dx and the rock density Dx_den into the wave impedance calculation formula to obtain the wave impedance value Dx_AI. Calculate the reflection coefficient according to the set sampling interval. Select a suitable wavelet and perform deconvolution calculation of the product of the reflection coefficient and the wavelet to obtain the synthetic seismic record based on the drilling index Dx. Step S6: Calculate the fitted sonic velocity Dx_Sim from the drilling index Dx of the entire well section, and calculate the rock density using Gardner's empirical formula. Finally, obtain the wave impedance Dx_AI of the entire well section based on the drilling index Dx, and complete the production of the synthetic seismic record of the entire well section.

2. The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 1, characterized in that, Step S3 further includes a step of comparing the time-depth relationship of the sonic velocity fitted by the drilling index Dx, specifically as follows: taking the well depth where the logging sonic velocity point begins as the starting point for comparison, converting the sonic velocity fitted by the logging and drilling index Dx into time per unit depth, calculating the cumulative time required as the depth increases, comparing the travel time of geological strata on the seismic profile with the time-depth relationship obtained by the logging and drilling index Dx fitted sonic velocity, and checking the differences between the seismic travel time of each stratum and the time-depth relationship calculated by the drilling and logging.

3. The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 1, characterized in that, Step S1 further includes: if different wellbore sections or different types of drill bits cause discontinuous segments in the drilling index Dx data, it is necessary to perform overall translation or addition / subtraction preprocessing on the data, and smooth out points with obvious ambiguity.

4. The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 1, characterized in that, The synthetic seismic record obtained from the well logging sonic calibration in step S2 is compared with the drilling index Dx, and the actual drilling index Dx result is made similar to or consistent with the well logging seismic calibration result by segmental correction.

5. The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 1, characterized in that, The formula for calculating the comprehensive parameter in step S3, which is the power exponent of the product of the logging sonic velocity and the drilling index Dx, as it increases with depth, is as follows: DT_Dx=(Depth) 1 / 6 ×(DT×Dx) 1 / 60 ; In the formula: DT is the acoustic velocity, Dx is the drilling exponent, and Depth is the well depth.

6. The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 1, characterized in that, The formula connecting the drilling index Dx and the comprehensive index constructed from the depth mentioned in step S4 is as follows: In the formula, DT_Dx is considered as DT_Dx_Trend, and DT is the sound wave Dx_Sim to be fitted. (Depth) 1 / 6 ×(Dx_Sim×Dx) 1 / 60 = 1.0497 × (Depth) 0.169972 The acoustic wave relationship fitted by the Dx exponent and depth is obtained as follows: Dx_Sim=(1.0497) 60 ×(Depth) 0.19833 / Dx; In the formula: Dx_Sim is the acoustic velocity fitted by the drilling index Dx, and Depth is the well depth.

7. The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 6, characterized in that, The formula for calculating rock density is as follows: Dx_den=0.31×((1 / Dx_Sim)×(1000000 / 3.28)) 0.25 ; In the formula: Dx_Sim is the acoustic velocity (us / ft) fitted to the drilling index Dx.

8. The method for establishing the well-seismic relationship across the entire well section based on the drilling index Dx according to claim 6, characterized in that, Using the wave impedance calculation formula, the wave impedance Dx_AI is calculated by fitting the acoustic wave Dx_Sim and density Dx_den to the drilling index Dx: Dx_AI=Dx_den×(1 / Dx_Sim)×(1000000 / 3.28); In the formula: Dx_den is the rock density calculated from the acoustic velocity fitted by the drilling index Dx; Dx_Sim is the acoustic velocity fitted by the drilling index Dx.

9. A system for establishing well-seismic relationships across the entire well section based on the drilling index Dx, characterized in that, Includes the following modules: Drilling index Dx calculation and processing module: Obtains drilling machine speed, total drill bit speed, drilling pressure and drill bit size during the drilling process, and calculates the dimensionless parameter Dx, which indicates the strength of the rock skeleton, using the formula; Well logging data well seismic calibration module for establishing time-depth relationship: acquire data of well sections with acoustic velocity and density logging projects, produce synthetic seismic records based on well logging data, determine the travel time of each stratum layer point on the seismic profile through well seismic calibration, and obtain the time-depth relationship curve calculated based on well logging data through regression; Well logging sonic wave and drilling index Dx trend line fitting module: Select well sections with well logging sonic wave data, construct a comprehensive parameter that shows the power exponent of the product of sonic wave velocity and drilling index Dx increases with depth, and perform regression analysis on this comprehensive parameter to obtain the relationship between the power exponent of the product of sonic wave velocity and Dx and depth; The module for fitting sonic velocity and correction to the drilling index Dx: By connecting the regression formula of the relationship between the power exponent of the product of sonic velocity and Dx and depth with the constructed comprehensive index formula of logging sonic velocity, drilling index Dx and depth, and substituting the sonic velocity DT as the dependent variable, the sonic velocity Dx_Sim fitted as the drilling index Dx changes is obtained. The drilling index Dx synthetic seismic record module: Based on the time-depth relationship determined by fitting the acoustic wave with the drilling index Dx, Dx_den is calculated using the acoustic velocity Dx_Sim fitted by the drilling index Dx and the Gardner rock density empirical formula. The acoustic wave impedance Dx_AI fitted by the drilling index Dx is calculated using the wave impedance calculation formula. The reflection coefficient is calculated according to the set sampling interval, and a suitable wavelet is selected to perform deconvolution calculation of the product of the reflection coefficient and the wavelet to obtain the synthetic seismic record based on the drilling index Dx. The module for creating synthetic seismic records for the entire well section using the drilling index Dx is as follows: The fitted sonic velocity Dx_Sim for the entire well section is calculated using the relationship between the drilling index Dx and the sonic velocity Dx_Sim. Then, Dx_den for the entire well section is calculated using Gardner's empirical formula for rock density. Finally, the wave impedance Dx_AI for the entire well section based on the drilling index Dx is obtained using the wave impedance calculation formula, and the creation of the synthetic seismic record for the entire well section is completed.

10. A system for establishing well-seismic relationships across the entire well section based on the drilling index Dx, as described in claim 9, characterized in that... It also includes: The module comparing the time-depth relationship of sonic velocity fitted by the drilling index Dx uses the well depth with logging sonic velocity as the initial point of calculation. It converts the sonic velocity fitted by the logging and drilling index Dx into time per unit depth, accumulates the time required with depth, and compares the travel time of seismic geological stratification with the time-depth relationship obtained by the logging and drilling index Dx fitted sonic velocity to check the differences between the synthetic seismic records made by drilling and logging.

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