CN106526679A - Method for recovering non-uniform erosion thickness through utilizing cycle analysis method - Google Patents

Abstract

The invention proposes a method for recovering unconformity denudation thickness by using cycle analysis method, which belongs to the technical field of geological exploration. According to the average formation deposition rate of the period, draw the deposition rate curve; determine the missing curve segment according to the deposition rate curve, calculate the period corresponding to the missing curve segment, and the abscissa corresponding to the peak and trough of the missing curve segment; divide the deposition rate curve to obtain a low frequency The wavelet and high-frequency wavelet calculate the ordinate corresponding to the peak and trough of the missing curve segment; restore the complete deposition rate curve according to the spectrum analysis, and calculate the unconformity denudation thickness by integrating the complete deposition rate curve. The invention can effectively restore the stratum deposition-denudation state in the whole geological history period, restore the denudation thickness of different denudation strata series, and the method has high accuracy and wide application range.

Description

A Method for Restoring Unconformity Denudation Thickness Using Cycle Analysis

technical field

The invention belongs to the technical field of geological exploration, and in particular relates to a method for recovering unconformity denudation thickness by using a cycle analysis method.

Background technique

Restoring the denuded thickness of unconformities is an important part of basin structural evolution analysis and hydrocarbon accumulation research, and the accuracy of the results has an important impact on the evaluation of source rock thermal evolution, reservoir development and transformation, hydrocarbon migration and accumulation and preservation conditions.

At present, there are many methods for recovering the denudation thickness of unconformities, including the mudstone acoustic time difference method, the vitrinite reflectivity method, the inclusion uniform temperature method, and the seismic trend analysis method based on seismic interpretation, the adjacent layer thickness ratio method, and the reference layer thickness change method. rate method, etc. However, practice has found that these methods still have some deficiencies: (1) Since the above-mentioned existing methods realize the quantitative recovery of denudation thickness by establishing a mathematical relationship, and the establishment of this mathematical relationship is often non-unique, thus As a result, the ablation thickness value has multiple solutions and large errors; (2) the above-mentioned existing methods have their own applicable conditions and limitations, for example: the vitrinite reflectance method requires more test data and is affected by thermal events It is very obvious; the seismic trend analysis method based on seismic interpretation needs to be established on the basis of a small denudation range in the study area, and is not applicable to areas where the denudation range covers the whole area; (3) because an unconformity may be the denudation product of a stratum , it may also be the denudation product of multiple layers. When the degree of denudation is large and multiple strata denudation forms an unconformity, the above existing methods can only restore a set of denudation thickness of the unconformity, that is, multi-layer denudation The sum of the thicknesses cannot recover the denuded thicknesses of different layers.

Therefore, how to provide a method with high accuracy, wide application range, and ability to restore the denudation thickness of different denudation layer systems is a technical problem that needs to be solved urgently.

Contents of the invention

Aiming at the above-mentioned technical problems that the existing methods for recovering unconformity denudation thickness have large errors, limited scope of application, and cannot restore denudation thicknesses of different layers, the present invention proposes a method for recovering unconformity denudation thickness by using cycle analysis method The method can effectively restore the sedimentation-denudation state of the study area in the entire geological history period, and can restore the denudation thickness of different denudation strata, and the method has high accuracy and wide application range.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for restoring unconformity denudation thickness using cycle analysis, comprising the following steps:

Sedimentation rate curve drawing: select the research area, combine the geological data of the research area, calculate the compaction coefficient and the original thickness of the strata before compaction through de-compaction correction, and determine the start time and end time of each stratum deposition according to the stratum chronology , calculate the average formation deposition rate in each depositional period, and draw the deposition rate curve;

Spectrum analysis of the deposition rate curve: determine the missing curve segment according to the cycle law of the deposition rate curve; calculate the period corresponding to the missing curve segment, the abscissa corresponding to the peak and trough of the missing curve segment according to the period value of the deposition rate curve before and after the missing curve segment; Perform frequency division processing on the deposition rate curve to obtain the corresponding low-frequency wavelet and high-frequency wavelet. According to the ordinates of the peaks and troughs of the corresponding low-frequency wavelet and high-frequency wavelet before and after the missing curve segment, the corresponding peaks and troughs of the missing curve segment are calculated. the ordinate;

Calculation of unconformity denudation thickness: restore the complete deposition rate curve according to the spectrum analysis results, and calculate the unconformity denudation thickness. The calculation formula of the unconformity denudation thickness is as follows:

Among them, He is the denudation thickness of unconformity, unit: m; F(t) is the function of the complete deposition rate curve; H _oc is the original thickness of the formation obtained by integrating F(t) _during the deposition period; H _r is the present residual Thickness, unit: m; C is the total compaction coefficient; t ₁ is the start time of denudation formation deposition, unit: Ma; t ₂ is the end time of denudation formation deposition, unit: Ma;

As preferably, in the deposition rate curve drawing step, the calculation formula of the original thickness of the formation before compaction is:

H ₀ ＝H _s /C _s +H _m /C _m

Among them, H ₀ is the original thickness before formation compaction, unit: m; H _s is the thickness of sandstone, unit: m; C _s is the sandstone compaction coefficient, calculated by using the de-compaction correction method; H _m is the thickness of mudstone, Unit: m; C _m is the mudstone compaction coefficient, which is calculated by decompaction correction method;

When calculating the unconformity denudation thickness, the calculation formula of the total compaction coefficient is:

Among them, C is the total compaction coefficient; H _s is the sandstone thickness, unit: m; C _s is the sandstone compaction coefficient, calculated by using the de-compaction correction method; H _m is the mudstone thickness, unit: m; C _m is the mudstone The compaction coefficient is calculated using the decompaction correction method.

Preferably, the geological data include stratum stratification data, stratum chronology, and mud logging data or porosity data.

Preferably, the de-compaction correction method is an empirical formula method or a porosity-lithology method; when the geological data includes mud logging data, the de-compaction correction method uses an empirical formula method; when the geological data When porosity data is included, the decompaction correction method uses the porosity-lithology method.

Preferably, after the step of calculating the denuded thickness of the unconformity, it further includes a step of verifying the accuracy of the denuded thickness of the unconformity by using the layered stratum data or the existing method for recovering the denuded thickness of the unconformity.

As a preference, the specific steps for verifying the accuracy of stratum stratification data are as follows: using the recovered complete deposition rate curve, the original thickness of the non-denuded stratum is obtained by integrating the deposition rate curve segment corresponding to the stratum that has not been denuded, and by compressing The thickness of the undenuded strata after compaction is obtained through actual calculation, and compared with the current stratum thickness in the stratum stratification data to verify the accuracy.

Preferably, the existing methods for restoring unconformity denudation thickness are selected from mudstone acoustic transit time difference method, vitrinite reflectance method, apatite fission track method, material balance method, inclusion uniform temperature method, deposition rate method, Any one of sandstone porosity method, wave analysis method, seismic trend analysis method, adjacent layer thickness ratio method and reference layer thickness change rate method.

Compared with prior art, advantage and positive effect of the present invention are:

1. The present invention can effectively restore the stratum deposition-denudation state in the entire geological history period of the research area, and restore the original thickness of the stratum deposition in any time range, so as to restore the denudation thickness of different denudation strata, which can be used for structural evolution, oil and gas It lays an important foundation for research on migration directions in different historical periods, which is conducive to reducing the risk of oil and gas exploration;

2. The present invention only utilizes basic data such as stratum stratification data, stratum chronology, mud logging data and porosity data, and the requirements for data are simple and the amount of data needed is less, eliminating the small amount of experimental data or machine errors, The error caused by the difference in sample selection improves the accuracy;

3. The present invention has no special restrictions and requirements on the denudation range or formation pressure of the research area, and has a wider scope of application;

4. The present invention does not rely on experiments, does not require the support of special experimental equipment, and is simple to operate and lower in cost.

Description of drawings

Fig. 1 is a flowchart of a method for recovering unconformity denudation thickness by using cycle analysis method provided by an embodiment of the present invention;

Fig. 2 is the line diagram of the sedimentation rate before the recovery of the B202 well provided by Example 1 of the present invention;

Fig. 3 is the deposition rate curve figure before the recovery of B202 well that the embodiment of the present invention 1 provides;

Fig. 4 is the low-frequency wavelet curve corresponding to the sedimentation rate curve before recovery of B202 well provided by Example 1 of the present invention;

Fig. 5 is the high-frequency wavelet curve corresponding to the sedimentation rate curve before recovery of B202 well provided by Example 1 of the present invention;

Fig. 6 is the complete deposition rate line diagram of the B202 well provided by Example 1 of the present invention;

Fig. 7 is the complete deposition rate curve diagram of B202 well that the embodiment of the present invention 1 provides;

Fig. 8 is the low-frequency wavelet curve corresponding to the complete deposition rate curve of Well B202 provided by Example 1 of the present invention;

Fig. 9 is a high-frequency wavelet curve corresponding to the complete deposition rate curve of Well B202 provided in Example 1 of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

An embodiment of the present invention provides a method for recovering unconformity denudation thickness by using cycle analysis method, the flow chart of which is shown in Figure 1, including the following steps:

S1 Sedimentation rate curve drawing: select the research area, combine the geological data of the research area, calculate the compaction coefficient and the original thickness of the stratum before compaction through de-compaction correction, and determine the start time and end of each stratum deposition according to the stratum chronology time, calculate the average formation deposition rate in each deposition period, and draw the deposition rate curve.

In this step, it should be noted that since the stratum deposited later has a compaction effect on the strata deposited earlier, the original thickness of the strata before compaction can be obtained through decompaction correction, and the average The formation deposition rate is closer to the true formation deposition rate in this depositional period. The calculation formula of the average formation deposition rate is:

V＝H ₀ /(t ₄ -t ₃ ) (1)

In formula (1), V is the average stratum deposition rate in each deposition period, unit: m/Ma; H ₀ is the original thickness before strata compaction, unit: m; t ₃ is the start time of strata deposition in each deposition period, unit : Ma; t ₄ is the end time of strata deposition in each depositional period, unit: Ma.

In addition, it should be noted that the deposition rate curve can be drawn using Matlab software, with the time as the abscissa and the average formation deposition rate as the ordinate to draw a line graph of the deposition rate, and further obtain the deposition rate curve by the cubic spline interpolation method .

Spectrum analysis of the S2 deposition rate curve: determine the missing curve segment according to the cycle law of the deposition rate curve; calculate the period corresponding to the missing curve segment and the abscissa corresponding to the peak and trough of the missing curve segment according to the period values of the deposition rate curve before and after the missing curve segment Carry out frequency division processing on the deposition rate curve to obtain the low-frequency wavelet and high-frequency wavelet corresponding to the deposition rate curve, and calculate the ordinate corresponding to the peak and trough of the missing curve segment according to the low-frequency wavelet and high-frequency wavelet.

In this step, it needs to be explained that since the deposition of the stratum has a certain cyclical characteristic, the specific performance is that the deposition rate of the stratum presents an approximately sinusoidal fluctuation, and its period, peak and trough values all present a certain gradual change rule. However, the denudation of the formation will cause the loss of deposition rate data, which will affect the cycle law of the deposition rate curve. Therefore, it can be determined that a segment of the curve in the deposition rate curve that is inconsistent with the cycle rule before and after is the missing curve segment. In addition, the accuracy of the time interval corresponding to the missing curve segment can be verified by combining the regional geological data and geophysical response (that is, mutation of logging curve, identification of seismic unconformity, etc.).

At the same time, the period, peak and trough values of the deposition rate curve also show a certain linear gradual change law, that is, the period, peak and trough values of the deposition rate curve show a law of decreasing or increasing. Moreover, the time corresponding to the missing curve segment must be between the front and back curves, that is, the time constraint principle. Therefore, using this linear gradient law and the principle of time constraints, according to the period values of the deposition rate curve before and after the missing curve segment, the number of missing cycles of the missing curve segment can be calculated, and the period corresponding to the missing curve segment and the missing curve segment can be further calculated. The abscissa corresponding to the peak and trough.

In addition, although the values of the vertical coordinates corresponding to the peaks and troughs of the missing curve segment (that is, the deposition rate) can also be calculated in the same way, the deposition rate curve is divided by frequency using the idea of decomposition and reconstruction, and the fluctuations of the high-frequency wavelet obtained It can reflect the cycle law of deposition, and the fluctuation of low-frequency wavelet can reflect the general trend of deposition. The data calculated from this are more accurate, which is conducive to improving the accuracy of spectrum analysis. Specifically, the deposition rate curve is frequency-divided to obtain the low-frequency wavelet and the high-frequency wavelet, and the peak values corresponding to the two wavelets are read respectively, and the total peak value Yc can be obtained by superimposing the two wavelets, and the valley value can be obtained in the same way Yt. Through this method, the corresponding peak and trough values of the deposition rate curve before and after the missing curve segment are calculated, and then the ordinate corresponding to the peak and trough of the missing curve segment can be calculated by using the linear gradient law.

It should also be noted that the frequency division processing can be completed in Matlab software, and the specific steps are: obtain the low-frequency wavelet of the deposition rate curve by (i-N+1) N-point averaging method, subtract the deposition rate curve from the High frequency wavelets are obtained from the low frequency wavelets. Among them, the N-point averaging method is specifically: for any one-dimensional data x, select a fixed time window For each sampling point x _i in the data, the average value is calculated by sliding the time window step by step, and the calculation process can be expressed as:

In formula (2), i is the number of data points; t _i is the time point corresponding to the i-th data point; N is the number of data sampling points; j is the cycle variable; Δt is the time sampling interval.

S3 Calculation of unconformity denudation thickness: restore the complete deposition rate curve according to the spectrum analysis results, and calculate the unconformity denudation thickness, the calculation formula of the unconformity denudation thickness is as follows:

In this step, the complete deposition rate curve can be restored according to the period corresponding to the missing curve segment obtained by spectrum analysis, the abscissa and ordinate corresponding to the peak and trough of the missing curve segment, wherein the peak is the period of the largest deposition rate, The trough is the period of the minimum deposition rate, and this curve can truly reflect the cycle change of deposition rate and the depositional evolution process. Furthermore, by integrating the complete deposition rate curve, the original thickness of the uncompacted strata can be obtained, and the thickness can be calculated by using the total compaction coefficient calculated before, and the original thickness of the stratum can be obtained, while denudation Thickness is the difference between the original thickness of the formation and the present residual thickness. Therefore, the unconformity denudation thickness can be calculated by using formula (3). It should be noted that the parameters _t1 and _t2 in formula (3) are for the start and end time of the deposition of a specific denuded formation, so the method for recovering the denuded thickness of unconformity by using the cycle analysis method provided in this embodiment can be aimed at Different denuded formations are calculated separately, and then the denuded thickness of different denuded strata can be recovered.

In a preferred embodiment, in the deposition rate curve drawing step, the calculation formula of the original thickness of the formation before compaction is:

H ₀ =H _s /C _s +H _m /C _m (4)

When calculating the unconformity denudation thickness, the calculation formula of the total compaction coefficient is:

In this embodiment, the calculation formula of the original thickness of the formation before compaction and the calculation formula of the total compaction coefficient are further defined. It should be noted that since the formation contains sandstone and/or mudstone, the compaction of sandstone and mudstone The coefficients are different, therefore, separate decompaction corrections are required for sandstone and mudstone.

In a preferred embodiment, the geological data include stratum stratification data, stratum chronology, and mud logging data or porosity data. This embodiment further defines the optimal combination of geological data. It can be understood that this embodiment is not limited to the types of geological data listed above, and may also be other commonly used geological data known to those skilled in the art.

In a preferred embodiment, the de-compaction correction method is an empirical formula method or a porosity-lithology method; when the geological data includes mud logging data, the de-compaction correction method uses an empirical formula method; when When the geological data includes porosity data, the de-compaction correction method adopts a porosity-lithology method. This embodiment further defines the de-compaction correction method. It should be noted that those skilled in the art can select a suitable de-compaction correction method according to the type of geological data and formation lithology characteristics. Moreover, this embodiment is not limited to the decompaction correction methods listed above, and other commonly used decompaction correction methods well known to those skilled in the art may also be used.

In addition, it should be noted that the formula for calculating the compaction coefficient using the empirical formula method is:

C'＝b-alnH (6)

In formula (6), when calculating the compaction coefficient of sandstone, C' is C _s ; when calculating the compaction coefficient of mudstone, C' is C _m ; a and b are constants, and a=0.08, b = 1.37, a = 0.1, b = 1.46 for mudstone; H is the burial depth, unit: m.

Using the porosity-lithology method, that is, the formula for calculating the compaction coefficient using the relationship between porosity and depth of different lithologies is:

In formula (7), when calculating the compaction coefficient of sandstone, C” is C _s ; when calculating the compaction coefficient of mudstone, C” is C _m ; H is the burial depth, unit: m; is the porosity at depth H; is the initial surface porosity.

In a preferred embodiment, after the step of calculating the denuded thickness of unconformity, it also includes the step of verifying the accuracy of denuded thickness of unconformity obtained by using stratigraphic data or the existing method of recovering denuded thickness of unconformity, through which verification step can ensure The accuracy of the resulting unconformity denudation thickness.

In a preferred embodiment, the specific steps of using the stratum stratification data to verify the accuracy are as follows: using the restored complete deposition rate curve, by integrating the deposition rate curve segment corresponding to the non-denuded stratum to obtain the original value of the undenuded stratum Thickness: Calculate the thickness of the undenuded stratum after compaction through compaction calculation, and compare it with the current stratum thickness in the stratum stratification data to verify the accuracy. In this embodiment, the accuracy of the obtained unconformity denuded thickness can be verified by the difference between the compacted stratum thickness of the undenuded stratum and the current stratum thickness. This verification method does not require the support of other methods and data, and the operation Simple, low effort and low cost.

In a preferred embodiment, the existing method for recovering unconformity denudation thickness is selected from the mudstone acoustic transit time difference method, vitrinite reflectance method, apatite fission track method, material balance method, inclusion uniform temperature method, Any one of sedimentation rate method, sandstone porosity method, wave analysis method, seismic trend analysis method, adjacent layer thickness ratio method and reference layer thickness change rate method. In this embodiment, it should be noted that those skilled in the art can specifically select an appropriate existing method for restoring unconformity denudation thickness for verification according to geological data and applicable conditions of existing methods for restoring unconformity denudation thickness. Moreover, the verification method adopted in this embodiment is not limited to the method for recovering the denudation thickness of the disconformity listed above, and may also be other commonly used methods known to those skilled in the art.

In order to more clearly and detailedly introduce the method for recovering the thickness of unconformity denudation by using the cycle analysis method provided by the embodiments of the present invention, the following will be described in conjunction with specific embodiments.

Example 1

In the Longfengshan area of the Changling fault depression in the Songliao Basin, a typical well B202 was selected. This well is located in the southeast gentle slope of the Longfengshan area. The Cretaceous strata drilled by the well are Mingshui Formation, Sifangtai Formation, Nenjiang Formation, Yaojia Formation, Qingshankou Formation, Quantou Formation, Denglouku Formation, Yingcheng Formation, Shahezi Formation (not penetrated).

To restore the unconformity denudation thickness of Well B202, the steps are as follows:

S1 deposition rate curve drawing:

Combining the stratum stratification data, stratum chronology and mud logging data of Well B202, the decompaction correction is carried out through the empirical formula method, the compaction coefficient is calculated by formula (6), and the original thickness of the formation before compaction is calculated by formula (4) , according to the stratigraphic chronology to determine the start time and end time of each stratum deposition, using formula (1) to calculate the average stratum deposition rate in each stratum deposition period of the well, the data are shown in Table 1.

Table 1 Statistics of the average formation deposition rate of each formation deposition period in Well B202

Table 1 (Continued) Statistics of the average formation deposition rate of each formation deposition period in Well B202

According to the calculation results in Table 1, Matlab software was used to draw the sedimentation rate line diagram of Well B202, as shown in Fig. 2, with time as the abscissa and the average formation deposition rate as the ordinate. The deposition rate curve is obtained by the cubic spline interpolation method, as shown in Fig. 3 .

Spectrum analysis of S2 deposition rate curve:

According to the cycle law of the deposition rate curve in Fig. 3, it can be clearly seen that data is missing between the seventh point and the eighth point, and the time interval corresponding to the missing curve segment is determined to be 109.835Ma-118Ma. According to the frequency spectrum analysis of Fig. 2 and Fig. 3, it can be seen that the curve before the missing curve segment (i.e. 94.25Ma-109.835Ma time) is 2 periods, and its average period T ₁ =7.7925Ma; after the missing curve segment (i.e. 118Ma-135.1429 The curve in Ma time) is 2.75 periods, and its average period T ₂ =6.234Ma. It can be concluded that the period of the deposition rate curve decreases with age from young to old. In addition, according to the cycle law of the deposition rate curve in Fig. 3, it can be seen that the missing curve segment should be 1.25 periods, that is, a peak and a trough are missing. Therefore, the average period of the missing curve segment is 6.532Ma. According to the principle of linear gradient and time constraints , the abscissa corresponding to the peak of the missing curve segment (that is, the time value) is 113.0605Ma, and the abscissa corresponding to the trough is 116.286Ma.

The deposition rate curve in Figure 3 is subjected to frequency division processing, and the low-frequency wavelet is extracted by formula (2), as shown in Figure 4, the high-frequency wavelet is obtained by subtracting the low-frequency wavelet from the deposition rate curve, as shown in Figure 5 Show. From Figure 4 and Figure 5, respectively read the peak values corresponding to the low-frequency wavelet and the high-frequency wavelet before the missing curve segment, and superimpose the two to obtain the peak value Yc ₁ = 81.79 before the missing curve segment, and similarly obtain the peak value before the missing curve segment The trough value Yt ₁ =43.87; similarly, the peak value Yc ₂ =148.68 and the trough value Yt ₂ =39.01 after the missing curve segment are obtained. Using the linear gradient of the peak and trough values of the deposition rate curve, it can be deduced that the ordinate corresponding to the peak of the missing curve segment (ie, the deposition rate) is 115.235m/Ma, and the ordinate corresponding to the trough is 41.44m/Ma.

S3 calculates the unconformity denudation thickness:

According to the above spectrum analysis results, the two data points (113.0605, 115.235) and (116.286, 41.44) are added to the data in Figure 2, and the complete deposition rate broken line diagram drawn is shown in Figure 6, corresponding to the complete deposition rate curve The figure is shown in Figure 7, and the corresponding low-frequency wavelet and high-frequency wavelet curves are shown in Figure 8 and Figure 9, respectively. The denuded formation in Well B202 is the Denglouku Formation (112Ma-124Ma). The total compaction coefficient C corresponding to the Denglouku Formation is calculated by formula (5) to be 0.7207, and C = 0.7207, t ₁ = 112Ma, t ₂ =124Ma, H _r = _318.8m Substituted into formula (3), the unconformity denudation thickness He of the Denglouku Formation is calculated to be 379.69m.

S4 method verification:

Use the stratum stratification data to verify, use the recovered complete deposition rate curve, get the original thickness of the non-denuded stratum by integrating the deposition rate curve segment corresponding to the non-denuded stratum, and obtain the compaction of the non-denuded stratum through compaction calculation After formation thickness, the data are shown in Table 2.

Table 2 Statistical table of verification results using stratigraphic stratification data of Well B202

Comparing the thickness of the undenuded strata after compaction with the present stratum thickness obtained from the stratum stratification data, as shown in Table 2, the error rates of the strata except the Qingshankou Formation are all less than 10%. According to the relevant literature on the tectonic evolution history of the Songliao Basin, it can be seen that the strata of the Qingshankou Formation have undergone stratum denudation, and the error of this stratum is caused by stratum denudation. It can be seen that the method for recovering the denudation thickness of unconformity provided by the cycle analysis method provided in this embodiment is reliable and effective.

Example 2

The difference from Example 1 is that this example uses the mudstone sonic transit time method to verify the accuracy of the obtained unconformity denudation thickness. Except for the method verification step, the other steps and the data results obtained are the same as in Example 1. Since the mudstone sonic transit time method is a commonly used method to restore the denuded thickness of unconformity, it will not be described here. The unconformity denudation thickness of the Denglouku Formation in Well B202 calculated in this example is 379.69m, and the result calculated by the mudstone sonic time difference method is 408.19m, and the error rate of the two is 6.98%, less than 10%. It can be seen that this implementation The method of recovering the denudation thickness of unconformity provided by the cycle analysis method is reliable and effective.

Example 3

Restoring the unconformity denudation thickness of Well B204 in the Longfengshan area of the Changling Fault Depression in the Songliao Basin. Except for the method verification steps, the rest of the steps are the same as in Example 1. The calculated unconformity denudation thickness of Well B204 is 418.09m. This example The accuracy of the obtained unconformity denudation thickness was verified by inclusion homogeneous temperature method. Since the inclusion uniform temperature method is a commonly used method to restore the thickness of unconformity denudation, it will not be repeated here. The result calculated by the method of uniform temperature of the first type of inclusion is 388.58m, with an error rate of 7.60%; the result calculated by the method of uniform temperature of the second type of inclusion is 446.15m, with an error rate of 6.29%. It can be seen that the method for recovering the denudation thickness of unconformity provided by the cycle analysis method provided in this embodiment is reliable and effective.

Claims (7)

1. a kind of method that utilization Cyclic Analysis method recovers unconformity erosion sediment thickness, it is characterised in that comprise the following steps：

Sedimentation rate Drawing of Curve：Research area is chosen, the geologic information in binding area calculates compacting system by decompaction correction The original thickness on front stratum is counted and is compacted, initial time and the end time of each sedimentation are determined according to stratigraphical time table, The average stratum sedimentation rate of each deposition phase is calculated, sedimentation rate curve is drawn；

The spectrum analysis of sedimentation rate curve：Disappearance curved section is determined according to the cycle rule of sedimentation rate curve；According to disappearance The periodic quantity of sedimentation rate curve before and after curved section, calculates disappearance curved section corresponding cycle, disappearance curved section crest and trough Corresponding abscissa；Scaling down processing is carried out to sedimentation rate curve and obtains correspondence lower frequency wavelet and high-frequency wavelet, it is bent according to disappearance The ordinate of the crest and trough of corresponding lower frequency wavelet and high-frequency wavelet before and after line segment, calculates disappearance curved section crest and trough Corresponding ordinate；

Calculate unconformity erosion sediment thickness：Complete sedimentation rate curve is recovered according to result of spectrum analysis, unconformity is calculated and is degraded Thickness, the computing formula of the unconformity erosion sediment thickness are as follows：

Wherein, H_eFor unconformity erosion sediment thickness, unit：m；F (t) is deposited intact rate curve function；H_ocIt is in sedimentation time Original thickness F (t) integrations obtained in section；H_rFor residual thickness now, unit：m；C is total compacting factor；t₁For stripping Erosion sedimentation time started, unit：Ma；t₂To degrade sedimentation end time, unit：Ma.

2. the method that utilization Cyclic Analysis method according to claim 1 recovers unconformity erosion sediment thickness, it is characterised in that In sedimentation rate Drawing of Curve step, the computing formula of the original thickness for being compacted front stratum is：

H₀=H_s/C_s+H_m/C_m

Wherein, H₀For the original thickness before formation compaction, unit：m；H_sFor sandstone thickness, unit：m；C_sFor sandstone compaction coefficient, Calculated using decompaction correction method and obtained；H_mFor mud stone thickness, unit：m；C_mFor mudstone compacting coefficient, using decompaction correction Method is calculated and is obtained；

When unconformity erosion sediment thickness is calculated, the computing formula of total compacting factor is：

Wherein, C is total compacting factor；H_sFor sandstone thickness, unit：m；C_sFor sandstone compaction coefficient, using decompaction correction method Calculate and obtain；H_mFor mud stone thickness, unit：m；C_mFor mudstone compacting coefficient, calculated using decompaction correction method and obtained.

3. the method that utilization Cyclic Analysis method according to claim 1 recovers unconformity erosion sediment thickness, it is characterised in that：Institute Stating geologic information includes strata division data, stratigraphical time table, and log data or porosity data.

4. the method that utilization Cyclic Analysis method according to claim 3 recovers unconformity erosion sediment thickness, it is characterised in that：Institute Decompaction correction method is stated for empirical formula method or porosity-lithology method；When the geologic information includes log data, institute State decompaction correction method and adopt empirical formula method；When the geologic information includes porosity data, the decompaction correction Method adopts porosity-lithology method.

5. the method that utilization Cyclic Analysis method according to claim 1 recovers unconformity erosion sediment thickness, it is characterised in that： After calculating unconformity erosion sediment thickness step, also include the method using strata division data or existing recovery unconformity erosion sediment thickness The step of checking gained unconformity erosion sediment thickness accuracy.

6. the method that utilization Cyclic Analysis method according to claim 5 recovers unconformity erosion sediment thickness, it is characterised in that profit Concretely comprising the following steps for Accuracy Verification is carried out with stratum individual-layer data：Using the deposited intact rate curve for recovering, by not The corresponding sedimentation rate curved section in stratum for degrading is integrated the original thickness for not degraded stratum, by compacting meter After the compacting on stratum is not degraded in calculation, formation thickness now in formation thickness, with strata division data is contrasted, and is verified Accuracy.

7. the method that utilization Cyclic Analysis method according to claim 5 recovers unconformity erosion sediment thickness, it is characterised in that：Institute State the existing method for recovering unconformity erosion sediment thickness and be selected from mud stone sonic time difference, vitrinite reflectance rate, apatite fission footpath Mark method, material balance method, inclusion enclave homogenization temperature method, sedimentary ratio analysis, sandstone porosity method, wave theory approach, seismic trend Any one in analytic approach, adjacent bed thickness ratio method and reference layer thickness change method.