Method for recovering denudation amount of sedimentary rock stratum

Abstract

The invention discloses a sedimentary rock stratum denudation amount recovery method. The method comprises the following steps: acquiring geological and structural backgrounds, sequence strata and logging information; carrying out Dobnishi wavelet noise reduction on the GR logging curves of the upper stratum and the lower stratum of the denudation surface to obtain a GR-denoise curve; carrying out astronomical cycle identification on the GR-dense curve to obtain astronomical response cycles and deposition durations of the two stratums; calculating to obtain the deposition initial time of the upper stratum of the denudation surface, perfecting a stratum deposition denudation time frame before and after the structure denudation motion, and recovering the deposition time and denudation time of the denudated stratum; the compaction thickness of the lower stratum of the denudation surface is recovered, and the original deposition thickness is obtained; dividing the original deposition thickness by the corresponding deposition time to obtain an original deposition rate; the original deposition rate is multiplied by the denudated stratum to obtain the original deposition thickness of the denudated stratum, and the denudation rate of the stratum is obtained by combining the denudation time. According to the method, when seismic data, ancient temperature scales and other data are insufficient, high-precision stratum denudation recovery is carried out based on single well GR logging data.

Description

Technical Field

[0001] The invention relates to a method for recovering the erosion amount of a sedimentary rock stratum, and belongs to the technical field of petroleum exploration and development. Background Art

[0002] Tectonic uplift, a key factor influencing oil and gas accumulation, controls the maturation and evolution of source rocks, the development of reservoirs, the formation of reservoir traps, and faults. Reconstructing the burial and erosion processes of sedimentary basins not only facilitates oil and gas exploration but also plays a crucial role in understanding reservoir tectonic evolution. Burial history reconstruction relies on the conversion of stratigraphic depth and time domains and the recovery of erosion volume. Erosion thickness is a key factor influencing burial history reconstruction and remains a hot topic in sedimentary basin research. Intense uplift and erosion can severely damage the basin's existing sedimentary structure, damaging reservoirs and caprocks and even leading to oil and gas leaks.

[0003] There are many technical methods used for stratum erosion restoration today.

[0004] The first category, geological analysis and comparison methods, involves comparing denuded and undenuded areas of the same stratigraphic unit to restore the missing stratum thickness in the denuded area. These methods include balanced geological profile comparison, adjacent stratum thickness ratios, reference layer thickness change rates, and seismic stratigraphic methods. These methods are suitable for well-studied areas with significant lateral variations in stratum thickness and significant differential compaction. This is particularly true when erosion is widespread across the region, making comparative studies difficult and resulting in significant errors in the restored results. The accuracy of the time-depth relationship of the seismic data also significantly impacts the restored results.

[0005] The second category, based on geophysical logging, primarily includes porosity and mudstone sonic transit time methods. Under normal compaction, basic rock parameters such as porosity and density vary regularly with depth. Erosion can cause porosity or sonic transit time curves to exhibit unusual depth variations. However, these methods are generally applicable to shallow burial conditions with significant erosion (thickness greater than the thickness of the strata above the unconformity). Therefore, accurate results are difficult to obtain if the erosion thickness is small, if sonic transit time and porosity data are unavailable, or if localized physical property anomalies are present.

[0006] The third category of commonly used methods based on paleothermal scales includes the vitrinite reflectance (Ro) method, the fluid inclusion method, the apatite fission track method, and the paleo-geothermal gradient method. The vitrinite reflectance (Ro) method assumes that Ro is linearly related to burial depth. When an unconformity exists in the stratum, Ro values ​​above and below the interface will suddenly change. However, because Ro undergoes annealing and ablation during complex geological evolution, the results calculated by this method can only be used as a minimum amount of denudation. Furthermore, this method requires sufficient field data on vitrinite reflectance, and sudden changes in vitrinite reflectance are likely caused by stratum denudation or tectonic thermal events. The fluid inclusion method theoretically assumes that during continuous sedimentation, the temperature and pressure at the time of fluid inclusion capture are linearly related to burial depth. When an unconformity exists in the stratum, the temperature and pressure environments represented by fluid inclusions in the strata above and below the unconformity may jump. However, the stringent sample selection requirements and complex pre-analysis conditions make this method difficult to implement and its accuracy is unsatisfactory. The apatite fission track method, which subsequently gained popularity, uses tracks produced by the spontaneous fission of U238 contained in apatite to determine the amount of erosion. Its unique characteristic is that it can provide both the amount of tectonic uplift and the timing of that uplift. However, since isotope dating has a limited temperature range, apatite (120°C) dating is only suitable for low and medium-low temperatures. Furthermore, it can only estimate the amount of erosion along unconformities formed after the strata reached their maximum paleotemperature. Furthermore, it is important to note that the track annealing temperature is affected by various factors.

[0007] The fourth category involves sedimentation rate analysis, including the sedimentation rate ratio method and the sedimentation rate trend method. These methods estimate the amount of erosion based on the sedimentation rate, erosion rate, and time. The advantage of this method is that it can be applied when the overlying sediment thickness exceeds the erosion volume, and can also be used for lateral comparisons in specific circumstances. However, the disadvantage is that the accuracy of each parameter in this method is problematic.

[0008] Other methods, including sedimentary wave process analysis, cosmogenic nuclide analysis, natural gas volume equilibrium concentration method, etc., are difficult to promote and apply due to their difficulty in operation, high cost or poor applicability. Overall, the recovery of erosion volume requires a more accurate, easy-to-operate and highly applicable calculation method. The present invention only uses GR logging data in conventional logging sequences. With the support of basic geological, structural and stratigraphic data, through the Dobesi wavelet transform and astronomical cycle identification method, it can effectively identify the age information of stratigraphic deposition and erosion processes, restore stratigraphic deposition and erosion thickness, and the results are reliable and have strong applicability in general clastic sedimentary strata. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for recovering the erosion amount of sedimentary rock strata in response to the problems existing in the prior art.

[0010] The present invention provides a technical solution to solve the above technical problems: a method for recovering the amount of erosion on a sedimentary rock stratum, comprising the following steps:

[0011] Step S10: Acquire geological background data, structural background data, sequence stratigraphic data, and GR logging data of the target work area;

[0012] Step S20: Determine the depth range and time anchor point of the studied formation, and obtain the bottom interface depth H1 of the lower formation, the depth of the eroded interface H2, the top interface depth H3 of the upper formation, the geological age time T3 of the top interface of the upper formation, the geological age time T1 of the top interface of the lower formation, the erosion start time T2, the formation compaction coefficient x, and the GR logging curves of the upper and lower formations;

[0013] Step S30: De-noising the GR logging curve using Dobesi wavelet transform to obtain de-noised formation gamma logging curves of the two sections of the strata above and below the denuded interface;

[0014] Step S40: Using the denoised gamma log curves GR-denoise of the two sections of the strata above and below the denuded interface as research indicators, Acycle software is used to extract astronomical periodic signals from the target work area, establish a floating astronomical scale for the strata in the target work area, obtain the response period of the astronomical cycle of the strata, and calculate the deposition time t1 of the strata below the denuded interface and the deposition time t2 of the strata above the denuded interface;

[0015] Step S50: Determine the deposition start time T1' and the denudation end time T2' of the denuded stratum based on the upper layer corresponding interface time T3, the lower layer corresponding interface time T1, the denudation start time T2, the deposition time t1 of the stratum below the denuded interface, and the deposition time t2 of the stratum above the denuded interface, thereby improving the deposition and denudation time frame of the stratum before and after the tectonic denudation movement, and the deposition time t1' and the denudation time t'2 of the denuded stratum.

[0016] Step S60: Obtain the original sedimentary thickness h of the lower stratum according to the bottom interface depth H1 of the lower stratum, the eroded interface depth H2, and the stratum compaction coefficient x. s ;

[0017] Step S70: Based on the original sedimentary stratum thickness h of the lower stratum s The average sedimentation rate v of the stratum is calculated by the sedimentation time t1 of the stratum below the eroded interface s ;

[0018] Step S80: According to the average sedimentation rate v s The thickness of the eroded stratum h is obtained by combining the deposition time t1' of the eroded stratum d ;

[0019] Step S90: Based on the thickness of the eroded stratum h d The average erosion rate v of the stratum is obtained by combining the erosion time t'2 of the eroded stratum d .

[0020] A further technical solution is that the GR logging curve in step S20 includes a H2-H3 formation GR curve and a H1-H2 formation GR curve.

[0021] A further technical solution is that the specific steps of step S30 are:

[0022] Step S31, performing Dobesi wavelet decomposition on the GR logging curves of the two sections of the strata above and below the denuded interface to obtain 8-layer wavelet decomposition curves;

[0023] Step S32: Perform Dobesi wavelet denoising on the 8-layer wavelet decomposition curves to obtain the denoised gamma logging curves GR-denoise of the two sections of strata above and below the denuded interface.

[0024] A further technical solution is that the specific steps of step S40 are:

[0025] Step S41, check the order of GR-denoise curve data, and delete abnormal values ​​and blank data rows;

[0026] Step S42: Check the distribution and sampling rate of the GR-denoise curve data to ensure that the sampling interval and sampling rate are normal;

[0027] Step S43: Check missing data and interpolate the missing data according to the existing sampling interval;

[0028] Step S44: first use the RAW detrending model to obtain the sliding window average sequence of the time series, and then use the LOWESS model to obtain the detrended time series;

[0029] Step S45: Perform a multi-taper method analysis on the detrended time series to identify the long eccentricity, short eccentricity, slope, period, and cycle thickness information;

[0030] Step S46: Based on the astronomical cycle identification, the data sequence is subjected to sliding window spectrum analysis and Gaussian bandpass filtering. Through the evolution spectrum analysis and filtering, the 405-kyr long eccentricity period is identified. The short eccentricity and slope periods are then tuned with the 405-kyr long eccentricity period to establish the astronomical age scale.

[0031] Step S47: Based on the identification of the astronomical age cycle and the corresponding number of cycles, the sedimentation time length of the current stratum is obtained, and the initial and final time nodes of the sedimentation of the strata in the H1-H2 depth segment and the H2-H3 depth segment are determined, that is, the sedimentation time length t of the strata below the eroded interface. 11 , the deposition time of the strata above the erosion interface is t2.

[0032] A further technical solution is,

[0033] The calculation formula of step S50 includes:

[0034] t'2=T2-T2'

[0035] t1'=T1'-T2

[0036] T1'=T1-t1

[0037] T2'=T3+t2

[0038] Where: t1 is the deposition time of the stratum below the eroded interface; t2 is the deposition time of the stratum above the eroded interface; t1' is the deposition time of the eroded stratum; t'2 is the denudation time of the eroded stratum; T3 is the time corresponding to the interface of the upper layer; T1 is the time corresponding to the interface of the lower layer; T2 is the start time of denudation; T2' is the end time of uplift and denudation; T1' is the end time of deposition of the residual stratum below the eroded interface.

[0039] A further technical solution is that the calculation formula of step S60 includes:

[0040] h s =h1 / x

[0041] h1=H1-H2

[0042] Where: H1 is the depth of the bottom interface of the lower stratum; H2 is the depth of the eroded interface; h s is the original sedimentary stratum thickness of the present residual stratum; h1 is the present stratum thickness; x is the stratum compaction coefficient.

[0043] A further technical solution is that the calculation formula of step S70 is:

[0044] v s =h s / t1

[0045] Where: v s Average sedimentation rate of the formation; h s is the thickness of the original sedimentary stratum of the present residual stratum; t1 is the deposition time of the stratum below the eroded interface.

[0046] A further technical solution is that the calculation formula of step S80 is:

[0047] h d =v s t1'

[0048] Where: h d is the thickness of the eroded stratum; v s The average sedimentation rate of the stratum; t1' is the sedimentation time of the eroded stratum.

[0049] A further technical solution is that the calculation formula of step S90 is:

[0050] v d =h d / t'2

[0051] Where: v d is the average erosion rate of the formation; h d is the thickness of the eroded stratum; t'2 is the erosion time of the eroded stratum.

[0052] The present invention has the following beneficial effects: When seismic data, paleothermal data, and other data are insufficient, this method uses single-well GR logging data to restore stratum erosion. GR logging curves are de-noised using Dobesi wavelets. By identifying astronomical cycles, a floating astronomical scale is established for the strata, providing a temporal framework for the sedimentary and erosive evolution of the strata. The present-day residual strata of the eroded strata are decompacted and restored to determine the thickness of the original sedimentary strata, and the original average sedimentation rate is calculated. This allows the thickness and erosion rate of the eroded strata to be restored. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a flow chart of the present invention;

[0054] Figure 2 Schematic diagram of stratigraphic evolution for denudation recovery;

[0055] Figure 3 This is the principle diagram of Dobesi wavelet decomposition of GR logging data;

[0056] Figure 4 Comparison diagram of original GR logging data and GR-denoise curve after Dobesi wavelet denoising;

[0057] Figure 5 This is the detrending result of the GR-denoise curve of the HG1 formation below the erosion surface;

[0058] Figure 6 This is the detrending result of the GR-denoise curve of the LJ formation in the upper part of the erosion surface;

[0059] Figure 7 This is the MTM spectrum analysis result of the HG1 formation below the erosion surface;

[0060] Figure 8 This is the result of MTM spectrum analysis of LJ formation in the upper part of the erosion surface;

[0061] Figure 9 This is the 405kyr GR-denoise filtering result of the HG1 formation below the erosion surface;

[0062] Figure 10 This is the 405kyr GR-denoise filtering result of the LJ Formation in the upper part of the erosion surface. DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0064] like Figure 1 As shown, the present invention provides a method for recovering the amount of sedimentary rock strata erosion, comprising the following steps:

[0065] Step S10: Acquire geological background data, structural background data, sequence stratigraphic data, and natural gamma ray logging data of the target work area;

[0066] Step S20: Determine the depth range and time anchor point of the studied formation, and obtain the bottom interface depth H1 of the lower formation, the depth of the eroded interface H2, the top interface depth H3 of the upper formation, the duration T3 of the upper layer corresponding interface, the duration T1 of the lower layer corresponding interface, the erosion start time T2, the formation compaction coefficient x, and the GR logging curves of the upper and lower formations.

[0067] According to the sequence stratigraphic division of the work area, the strata above and below the denuded interface were selected as the research strata, thus clarifying the above parameters;

[0068] Specifically, the strata studied in the example work area consist of the lower HG1 formation (H1-H2) and the upper LJ formation (H2-H3). The parameter principle information can be found in Figure 2 The bottom conformity interface depth H1 of the HG1 Formation is 3780.125 m, corresponding to an interface time T1 of 28.4 Ma. The eroded interface depth H2 is 2973.25 m. The top conformity interface H3 of the LJ Formation is 2478.625 m, corresponding to an interface time T3 of 16.4 Ma. The onset time of erosion (tectonic uplift) T2 is 23.03 Ma. The compaction coefficient of the HG1 Formation ranges from 0.68 to 0.72, and this setting uses the intermediate value x = 0.70.

[0069] The GR logging curve data corresponding to the H1-H2 depth section and the H2-H3 depth section are intercepted respectively; that is, the GR logging curve of the HG1 formation (3780.125-2973.25m) and the LJ formation (2973.25-2478.625m) in the example work area are intercepted;

[0070] Step S30: using Dobesi wavelet transform to reduce noise on the GR logging curve to obtain a denoised formation gamma logging curve;

[0071] Generally speaking, actual logging signals are often contaminated by other noise signals from the formation during the process of collection, acquisition and transmission, becoming noisy signals that affect their quality. When extracting information from them, denoising is often required.

[0072] Dobesi wavelet is mainly used in discrete wavelet transform and is the most commonly used wavelet transform. It is usually used in digital signal analysis, signal compression and noise removal.

[0073] Step S31, performing Daubechies wavelet decomposition of the GR logging curves corresponding to the formations in the H1-H2 depth segment and the H2-H3 depth segment, executing the wavelet-1D program in MATLAB software, selecting the wavelet function db (Daubechies Wavelet), and setting the decomposition scale to 8;

[0074] The GR logging curves of the HG1 formation and the LJ formation were input into the MATLAB software to execute the wavelet-1D program, and the wavelet function db wavelet was selected to decompose the GR with a decomposition scale of 8: GR = a8 + d8 + d7 + d6 + d5 + d4 + d3d + d2 + d1. Figure 3 ;

[0075] In step S32, the GR logging curves corresponding to the H1-H2 depth segment and the H2-H3 depth segment are denoised by Dobesi wavelet. The threshold is set to Fixed form threshold, the Hard noise reduction mode is selected, the number of wavelet decomposition layers is still 8, the noise structure is selected to be Unscaled white noise, and the Denoise option is executed to obtain the denoised HG1 group (H1-H2 depth segment) and LJ group (H2-H3 depth segment) formation gamma logging curves (GR-denoise). It can be seen that Figure 4 Comparison of curves before and after denoising.

[0076] Step S40: Using the GR-denoise curve as a research indicator, the Acycle software is used to extract the astronomical cycle signal of the target work area, establish a "floating astronomical scale" for the strata in the target work area, obtain the response period of the astronomical cycle of the strata, and calculate the deposition time length;

[0077] Step S41: Start the Acycle software program on the Matlab platform, open the GR-denoise curve data of the HG1 and LJ formations respectively, check the GR-denoise data sorting in ascending order through the Math-Sort / Unique / Delete empty operation, delete abnormal values ​​and blank data rows, and obtain data files with the -sue suffix;

[0078] Step S42: Perform a Plot-sampling rate operation on the data file with the -sue suffix to check the data distribution and sampling rate to ensure that the sampling interval and sampling rate are normal;

[0079] Step S43: Perform Math-interpolation operation to check for missing data and interpolate the missing data according to the existing sampling interval to obtain a data file marked with the sampling interval suffix;

[0080] Step S44: Detrend the data file obtained in step S43 by Timeseries-Detrending / curve fitting operation. First, use the "RAW" detrending model to obtain the sliding window average sequence of the time series, and then use the LOWESS (GREEN) model to obtain the detrended time series. The data file with the -LOWWESS suffix is ​​used for time series analysis. The detrended data series can be seen Figure 5 and Figure 6 .

[0081] Step S45: Perform a Multi-taper method (MTM) analysis on the detrended series using the Timeseries-Special Analysis operation. The peaks represent different astronomical orbital periods. Data with 99% and 95% confidence levels are selected, while data with confidence levels below 90% are selectively used to identify long eccentricity, short eccentricity, slope, period, and cycle thickness information.

[0082] The mean frequency of GR-denoise in the detrended HG1 formation is 0.006196m -1 , 0.007683m -1 , 0.009418m -1 , 0.0114m-1 , 0.01289m -1 , 0.02404m -1 , 0.02602m -1 , 0.02751m -1 , 0.02949m -1 , 0.1566m -1 , 0.2183m -1 , 0.2667m -1 , 0.3549m -1 The confidence level exceeds 99%, and the corresponding cycle thicknesses are 161.39m, 130.16m, 106.18m, 87.72m, 77.58m, 41.6m, 38.43m, 36.35m, 33.91m, 6.39m, 4.58m, 3.75m, and 2.82m. The frequency is 0.004213m -1 , 0.01809m -1 , 0.02107m -1 , 0.03123m -1 , 0.1358m -1 , 0.1497m -1 , 0.1509m -1 , 0.1524m -1 , 0.1638m -1 , 0.177m -1 , 0.1784m -1 , 0.1943m -1 , 0.2052m -1 , 0.2166m -1 , 0.2397m -1 , 0.2679m -1 , 0.2835m -1 , 0.3155m -1 , 0.3343m -1 The confidence level exceeds 95%, and the corresponding cycle thicknesses are 237.36m, 55.28m, 47.46m, 32.02m, 7.36m, 6.68m, 6.63m, 6.56m, 6.11m, 5.65m, 5.61m, 5.15m, 4.87m, 4.62m, 4.17m, 3.73m, 3.53m, 3.17m, 2.99m. Frequency 0.03321m -1 , 0.03618m -1 , 0.04734m -1 , 0.05428m -1 , 0.05551m -1 , 0.057m -1 , 0.08649m-1 , 0.09195m -1 , 0.09343m -1 , 0.1076m -1 , 0.1086m -1 , 0.1343m -1 , 0.1799m -1 , 0.1973m -1 , 0.2027m -1 , 0.2134m -1 , 0.2307m -1 , 0.2696m -1 , 0.282m -1 The confidence level exceeds 9%, and the corresponding cycle thicknesses are 30.11m, 27.64m, 21.12m, 18.42m, 18.01m, 17.54m, 11.56m, 10.88m, 10.70m, 9.29m, 9.21m, 7.45m, 5.56m, 5.07m, 4.93m, 4.69m, 4.33m, 3.71m, and 3.55m. Figure 7 .

[0083] The mean frequency of GR-denoise in the LJ formation detrended is 0.007683 m -1 、0.01051m -1 、0.01294m -1 、0.0182m -1 、0.02022m -1 、0.02224m -1 、0.03275m -1 、0.05378m -1 、0.0558m -1 、0.1541m -1 、0.1565m -1 、0.1589m -1 、0.1779m -1 、0.1828m -1 、0.2188m -1 、0.2418m -1 、0.2644m -1 、0.2717m -1 、0.3097m -1The confidence level exceeds 99%, and the corresponding cycle thicknesses are 130.16m, 95.15m, 77.28m, 54.95m, 49.46m, 44.96m, 30.53m, 18.59m, 17.92m, 6.49m, 6.39m, 6.29m, 5.62m, 5.47m, 4.57m, 4.14m, 3.78m, 3.68m, and 3.23m. The frequency is 0.01496m -1 、0.05903m -1 、0.1456m -1 、0.2458m -1 、0.2677m -1 、0.2762m -1 、0.2794m -1 、0.2814m -1 、0.3793m -1 The confidence level exceeds 95%, corresponding to cycle thicknesses of 66.85m, 16.94m, 6.87m, 4.07m, 3.74m, 3.62m, 3.58m, 3.55m, and 2.64m. Frequency 0.03033m -1 、0.09381m -1 、0.09583m -1 、0.09826m -1 、0.1314m -1 、0.1363m -1 、0.2374m -1 、0.2511m -1 The confidence level exceeds 90%, and the corresponding cycle thicknesses are 32.97m, 10.66m, 10.44m, 10.18m, 7.61m, 7.34m, 4.21m, and 3.98m. Figure 8 .

[0084] However, due to the huge mass of Jupiter in the geological history, the 405kyr (long eccentricity) period is very stable, and this information can be extracted from the complex mixed frequency information through filtering technology.

[0085] Based on the filtering results, data with 99% and 95% confidence levels were prioritized, while data with confidence levels below 90% were used selectively. The HG1 Formation's 405-kyr (long eccentricity) cycle thicknesses were 130.16 m (confidence > 99%), 32.02 m (confidence > 95%), 11.56 m (confidence > 90%), and 6.39 m (confidence > 99%), representing a 100-kyr short eccentricity, a 36-kyr slope, and a 20-kyr precession period. For the LJ Formation, 405-kyr (long eccentricity) cycle thicknesses were 54.94 m (confidence > 99%), 10.66 m (confidence > 95%), and 2.64 m (confidence > 99%), representing a 40-kyr slope and a 19-kyr precession period. The cycle thickness of 13.54 m (confidence < 90%) represents 100 short eccentricity cycles.

[0086] Step S46: Based on the astronomical cycle identification, the data sequence is subjected to sliding window spectrum analysis and Gaussian bandpass filtering. Through the evolution spectrum analysis and filtering, the 405-kyr long eccentricity period is identified. The short eccentricity and slope periods are then tuned with the 405-kyr long eccentricity period to establish the astronomical age scale.

[0087] To obtain the number of sedimentary cycles controlled by 405 kyr, the filtering cutoff frequencies of GR-denoise of HG1 and LJ formations were set to 0.00644 to 0.0089219 m -1 、0.01604~0.02037m -1 The number of sedimentary cycles obtained by the filter curve is between 6 ( Figure 9 ) and 10 ( Figure 10 ).

[0088] Step S47: Based on the identification of astronomical age cycles and the corresponding number of cycles, the sedimentation time length of the current strata is obtained, and the initial and ending time nodes of the sedimentation of the strata in the H1-H2 depth segment and the H2-H3 depth segment are calculated, that is, the sedimentation time length t1 of the strata below the eroded interface and the sedimentation time length t2 of the strata above the eroded interface.

[0089] Six 405-kyr sedimentary cycles were identified in the HG1 formation, corresponding to a t1 depositional period of 2.43 Ma. Ten 405-kyr sedimentary cycles were identified in the LJ formation, corresponding to a t2 depositional period of 4.3 Ma.

[0090] Step S50: Restore the deposition time and erosion time of the eroded stratum according to the start time of stratum structural uplift (erosion start time);

[0091] That is, the deposition time t1' and the erosion time t'2 of the eroded stratum are determined according to the time T3 of the upper layer corresponding to the interface, the time T1 of the lower layer corresponding to the interface, the start time T2 of erosion, the deposition time t1 of the stratum below the eroded interface, and the deposition time t2 of the stratum above the eroded interface;

[0092] t'2=T2-T2'

[0093] t1'=T1'-T2

[0094] T1'=T1-t1

[0095] T2'=T3+t2

[0096] Where: t1 is the deposition time of the stratum below the eroded interface; t2 is the deposition time of the stratum above the eroded interface; t1' is the deposition time of the eroded stratum; t'2 is the denudation time of the eroded stratum; T3 is the time corresponding to the interface of the upper layer; T1 is the time corresponding to the interface of the lower layer; T2 is the start time of denudation; T2' is the end time of uplift and denudation; T1' is the end time of deposition of the residual stratum below the eroded interface.

[0097] Specifically, HG1 formation sedimentation began at T1 = 28.4 Ma, corresponding to a depositional duration of t1 = 2.43 Ma. This means that the current residual formation deposition ended at T1' = 25.97 Ma. Sedimentation of the upper LJ formation ended at T3 = 16.4 Ma, corresponding to a depositional duration of t2 of 4.3 Ma. This means that its deposition began (and the denudation of the lower formation ended) at T2' = 20.7 Ma.

[0098] The denudation start time (tectonic uplift start time) is T2 = 23.03 Ma, the denudation deposition time of the HG1 formation is t1' = 2.94 Ma, and the denudation deposition time of the HG1 formation is t'2 = 2.33 Ma.

[0099] Step S60: Obtain the original sedimentary thickness h of the residual stratum according to the bottom interface depth H1 of the lower stratum, the depth of the eroded interface H2, and the stratum compaction coefficient. s ;

[0100] h s =h1 / x

[0101] h1=H1-H2

[0102] Where: H1 is the depth of the bottom interface of the lower stratum; H2 is the depth of the eroded interface; h s is the original sedimentary stratum thickness of the present residual stratum; h1 is the present stratum thickness; x is the stratum compaction coefficient;

[0103] The present-day thickness of the HG1 formation is h s=3780.125-2973.25=806.875m, stratum compaction coefficient x=0.70. Then the original sedimentary thickness of the present stratum of HG1 after decompaction is h s =806.875 / 0.7=1152.68m.

[0104] Step S70: Based on the original sedimentary stratum thickness h of the current residual stratum s The average sedimentation rate v of the stratum is calculated by the sedimentation time t1 of the stratum below the eroded interface s ;

[0105] v s =h s / t1

[0106] Where: v s Average sedimentation rate of the formation; h s is the thickness of the original sedimentary stratum of the present residual stratum; t1 is the deposition time of the stratum below the eroded interface;

[0107] The average sedimentation rate v of the stratum is calculated based on the original sedimentary stratum thickness and sedimentation time of the residual stratum. s =1152.68m / 2.43Ma=474.35m / Ma.

[0108] Step S80: According to the average sedimentation rate v s The thickness of the eroded stratum h is obtained by combining the deposition time t1' of the eroded stratum d ;

[0109] h d =v s t1'

[0110] Where: h d is the thickness of the eroded stratum; v s The average sedimentation rate of the stratum; t1' is the sedimentation time of the eroded stratum;

[0111] The calculation of denudation thickness is to multiply the deposition rate of the denuded stratum by the deposition time of the stratum to obtain the denuded stratum thickness h. d =474.35m / Ma*2.94Ma=1394.59m.

[0112] Step S90: Based on the thickness of the eroded stratum h d The average erosion rate v of the stratum is obtained by combining the erosion time t'2 of the eroded stratum d ;

[0113] v d =h d / t'2

[0114] Where: vd is the average erosion rate of the formation; h d is the thickness of the eroded stratum; t'2 is the erosion time of the eroded stratum;

[0115] The calculation of the stratum erosion rate is to divide the eroded stratum thickness by the stratum uplift and erosion time to obtain the average stratum erosion rate v d =1394.59m / 2.33Ma=598.54m / Ma.

[0116] The above description does not limit the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any technician familiar with the profession can use the technical content disclosed above to make some changes or modifications to equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for recovering the amount of erosion of a sedimentary rock formation, characterized in that: The following steps are involved: Step S10, obtaining geological background data, structural background data, sequence stratigraphic data, and GR logging data of the target work area; Step S20, determine the depth range and time anchor point of the studied stratum, and obtain the bottom interface depth H1 of the lower stratum whose eroded thickness is to be restored, the eroded interface depth H2, the top interface depth H3 of the upper stratum, the geological age time T1 of the top interface of the lower stratum, the geological age time T3 of the top interface of the upper stratum, the erosion start time T2, the stratum compaction coefficient x, and the GR logging curves of the upper stratum and the lower stratum; Step S30, using Dobesi wavelet transform to reduce noise on the GR logging curve, and obtain the denoised gamma logging curve GR-denoise of the two sections of the strata above and below the denuded interface; Step S40, using the denoised gamma logging curve GR-denoise of the two sections of the strata above and below the denuded interface as the research index, using the Acycle software to extract the astronomical period signal of the target work area, establishing a floating astronomical scale for the strata in the target work area, obtaining the response period of the astronomical cycle of the strata, and calculating the deposition time t1 of the strata below the denuded interface and the deposition time t2 of the strata above the denuded interface; Step S50, according to the geological age time T3 of the top interface of the upper stratum, the geological age time T1 of the top interface of the lower stratum, the erosion start time T2, the deposition time t1 of the stratum below the eroded interface, and the deposition time t2 of the stratum above the eroded interface, determine the deposition start time T1' and the erosion end time T2' of the eroded stratum, improve the deposition and erosion time frame of the stratum before and after the tectonic erosion movement, and restore the deposition time t1' and the erosion time t'2 of the eroded stratum; Step S60: Obtain the original sedimentary stratum thickness h of the lower stratum according to the bottom interface depth H1 of the lower stratum, the eroded interface depth H2, and the stratum compaction coefficient x. s ; Step S70: according to the original sedimentary stratum thickness h of the lower stratum s The average sedimentation rate v of the stratum is calculated by the sedimentation time t1 of the stratum below the eroded interface. s ; Step S80: According to the average sedimentation rate v of the stratum s The thickness of the eroded stratum h is obtained by the deposition time t1' of the eroded stratum d ; Step S90: according to the thickness of the eroded stratum h d The average erosion rate v of the stratum can be obtained by combining the erosion time t'2 of the eroded stratum d .

2. A method for recovering the amount of erosion of a sedimentary rock stratum according to claim 1, characterized in that: The GR logging curve in step S20 includes the H2-H3 formation GR curve and the H1-H2 formation GR curve.

3. The method for recovering the amount of erosion of a sedimentary rock stratum according to claim 1, characterized in that: The specific steps of step S30 are as follows: Step S31, performing Dobesi wavelet decomposition on the GR logging curves of the two sections of the strata above and below the denuded interface to obtain 8 layers of wavelet decomposition curves; Step S32, perform Dobesi wavelet denoising on the 8-layer wavelet decomposition curves to obtain the denoised formation gamma logging curve GR-denoise of the two sections of the strata above and below the denuded interface.

4. The method for recovering the amount of erosion of a sedimentary rock stratum according to claim 1, characterized in that: The specific steps of step S40 are as follows: Step S41, check the order of GR-denoise curve data, and delete abnormal values ​​and blank data rows; Step S42, check the distribution and sampling rate of GR-denoise curve data to ensure that the sampling interval and sampling rate are normal; Step S43, checking missing data and interpolating the missing data according to the existing sampling interval; Step S44, first use the RAW detrending model to obtain the sliding window average sequence of the time series, and then use the LOWESS model to obtain the detrended time series; Step S45, performing a multi-taper method analysis on the time series after detrending to identify the long eccentricity, short eccentricity, slope, period and cyclomatic thickness information; Step S46: Based on the astronomical cycle identification, the data sequence is subjected to sliding window spectrum analysis and Gaussian bandpass filtering. The 405-kyr long eccentricity period is identified through evolution spectrum analysis and filtering. The short eccentricity and slope periods are then tuned with the 405-kyr long eccentricity period to establish an astronomical age scale. Step S47, based on the identification of astronomical age cycles and the corresponding number of cycles, the deposition time length of the current strata is obtained, and the initial and ending time nodes of the deposition of the strata in the H1-H2 depth segment and the H2-H3 depth segment are determined, that is, the deposition time length t1 of the strata below the eroded interface, and the deposition time length t2 of the strata above the eroded interface.

5. The method for recovering the amount of erosion of a sedimentary rock stratum according to claim 1, characterized in that: The calculation formula of step S50 includes: t'2=T2-T2' t1'=T1'-T2 T1'=T1-t1 T2'=T3+t2 Wherein: t1 is the deposition time of the stratum below the eroded interface; t2 is the deposition time of the stratum above the eroded interface; t1' is the deposition time of the eroded stratum; t'2 is the denudation time of the eroded stratum; T3 is the interface time corresponding to the upper layer; T1 is the interface time corresponding to the lower layer; T2 is the start time of denudation; T2' is the end time of uplift and denudation; T1' is the end time of the deposition of the residual stratum below the eroded interface.

6. The method for recovering the amount of erosion of a sedimentary rock formation according to claim 1, characterized in that: The calculation formula of step S60 includes: h s =h1 / x h1=H1-H2 Where: H1 is the depth of the bottom interface of the lower stratum; H2 is the depth of the denuded interface; h s is the original sedimentary stratum thickness of the present residual stratum; h1 is the present stratum thickness; x is the stratum compaction coefficient.

7. The method for recovering the amount of erosion of a sedimentary rock stratum according to claim 1, characterized in that: The calculation formula of step S70 is: v s =h s / t1 Where: v s Average sedimentation rate of the formation; h s is the original sedimentary stratum thickness of the current residual stratum; t1 is the deposition time of the stratum below the eroded interface.

8. The method for recovering the amount of erosion of a sedimentary rock stratum according to claim 1, characterized in that: The calculation formula of step S80 is: h d =v s t1' Where: h d is the thickness of the eroded stratum; v s The average sedimentation rate of the stratum; t1' is the sedimentation time of the denuded stratum.

9. The method for recovering the amount of erosion of a sedimentary rock stratum according to claim 1, characterized in that: The calculation formula of step S90 is: v d =h d / t'2 Where: v d is the average erosion rate of the formation; h d is the thickness of the eroded stratum; t'2 is the erosion time of the eroded stratum.

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