A method of identifying and analyzing stratum structure based on shallow profile well-seismic combination

Abstract

The present invention discloses a stratigraphic structure identification and analysis method based on shallow profile and well seismic combination, comprising the steps of: loading shallow profile data; determining the borehole position and obtaining the seafloor depth; determining the borehole data type, formatting the borehole data so that the starting depth of the borehole data is consistent with the seafloor depth; the borehole data includes but is not limited to any one or more of dating data, grain size data, foraminifera data and paleomagnetic polarity data; converting the borehole data from depth to time to realize the calibration of the borehole data and the shallow profile; realizing the joint analysis and comparative verification of the dating data grain size foraminifera abundance and paleomagnetic data with the shallow profile data. This scheme changes the traditional method of analyzing shallow profile and drilling data separately, and combines the two, mutually verifying multiple drilling indicators (grain size, foraminifera, dating and paleomagnetism) with the shallow profile, so as to minimize the multi-solution and improve the reliability of shallow profile stratigraphic interpretation.

Description

Technical Field

[0001] The invention belongs to the field of marine seismic data interpretation, and in particular relates to a stratum structure identification and analysis method based on shallow-profile well-seismic combination. Background Art

[0002] In the study of stratigraphic sedimentary evolution since the Late Pleistocene, shallow stratigraphic profile measurement and acquisition costs are low, and can achieve large-scale underground stratigraphic structure identification, but it is impossible to determine the age and sedimentary characteristics of each stratum; while drilling costs are high, and the age and sedimentary characteristics of the obtained core can be determined, but it can only realize the underground stratigraphic structure at the drilling location, and cannot achieve large-scale underground stratigraphic structure identification. Combining the two can achieve complementary advantages, and this method has always been adopted in the study of the Late Quaternary, but the existing method is to study the two separately, and finally piece together the research results of the two. There is a big problem with this method, that is, both the interpretation of the shallow stratigraphic structure and the interpretation of the drilling have certain multi-solutions, and the interpretation alone is very subjective and may not match the actual situation. The conclusion obtained by forcibly fitting the results of the two may not be correct.

[0003] Boreholes can provide a lot of technical indicators, such as grain size, foraminifera abundance, paleomagnetism, dating, etc. In order to better realize the joint analysis of borehole parameters and shallow profiles, combined with the characteristics of shallow seismic profiles, it is urgent to propose a new idea for shallow profile well-seismic joint analysis, which can provide more accurate and reliable conclusions through strict comparison and mutual verification of various indicators, so as to minimize the uncertainty of borehole data comparison. Summary of the invention

[0004] In order to solve the defects in the prior art of studying shallow profile and drilling data separately and then directly combining the results for analysis, the present invention proposes a formation structure identification and analysis method based on shallow profile and well seismic combination, which provides more accurate and reliable conclusions through strict comparison and mutual verification of various indicators.

[0005] The present invention is implemented by adopting the following technical scheme: a method for identifying and analyzing stratum structure based on shallow profile well-seismic combination, comprising the following steps:

[0006] Step 1: Load shallow section data, where the shallow section coordinates loaded are coordinates representing the actual position;

[0007] Step 2: determine the drilling location and obtain the seabed depth according to the drilling location;

[0008] Step 3, data index selection and data format arrangement: determine the type of borehole data and format the borehole data; the borehole data includes but is not limited to any one or more of dating data, grain size data, foraminifera data and paleomagnetic polarity data;

[0009] Step 4, calibration of drilling data and shallow profile: the shallow profile coordinate is time, the drilling data coordinate is depth, and the drilling data is converted from depth to time to achieve matching between drilling data and shallow profile;

[0010] Step 5: Based on the characteristics of drilling data, realize the comparison and verification of drilling data and shallow section.

[0011] Furthermore, in step 5, the type of borehole data is dating data, and the dating data and earthquake data are compared and verified in the following manner:

[0012] According to the dating results, the sedimentary periods are divided in order from top to bottom, and the seismic phase characteristics within the divided sedimentary periods are observed to see whether they are consistent with the seismic phase characteristics of the theoretical sedimentary periods; if they are basically consistent, the next sedimentary period is compared until all the dating results are verified by seismic phase comparison; if individual dating results are inconsistent, they are discarded; if a large number of dating results are inconsistent with the seismic phases, the reliability of the dating results is poor and needs to be re-compared and verified.

[0013] Furthermore, in step 5, the drilling data type is particle size data, and the average particle size is used as the particle size data indicator. When comparing and verifying the particle size with the shallow profile data, the following method is specifically used:

[0014] (1) Determination of important interfaces: The change in wave impedance is characterized by the change in average grain size, so as to establish the corresponding relationship between shallow section and grain size data. The shallow section is used as a reference to delineate the seismic layer interface of shallow section interpretation;

[0015] (2) Analysis of the trend of particle size changes within the interface: the combination of increase, stability and decrease in particle size data corresponds to the periodic cooling and warming of the climate;

[0016] (3) The analysis scope is determined by dividing the layers according to the results of the well-seismic combination, and the grain size change period is divided according to the specific situation of the grain size change. The relationship between the location of the grain size mutation point and the important interface is determined according to the law of grain size change. If there is a one-to-one correspondence, it means that the grain size data results are highly reliable.

[0017] Furthermore, in step 5, the borehole data type is foraminifera data, and foraminifera abundance is used as the foraminifera data indicator. The joint analysis process of foraminifera abundance and shallow profile is as follows:

[0018] (1) According to the continuity of foraminifera abundance, the marine and terrestrial facies were preliminarily divided into groups: the continuous sedimentary assemblages with zero foraminifera abundance were classified as terrestrial deposits, and the rest were marine deposits;

[0019] (2) Determine the relationship between the marine-continental interface and the shallow profile impedance interface: define the hard contact and soft contact of foraminiferal abundance changes. The hard contact refers to the sudden change of foraminiferal content at the marine-continental boundary, and the soft contact refers to the slow change of foraminiferal content at the marine-continental boundary.

[0020] (3) Joint analysis of the changes in marine and continental phases and shallow seismic phases within the interface: If the seismic phases within the interface indicated by the foraminifera abundance are consistent, and the position of the foraminifera mutation point basically shows a good coincidence relationship with the shallow strong wave impedance interface, and at the same time there is a good correspondence between sedimentary discontinuities, marine and continental phase changes and shallow seismic phases, it indicates that the calibrated data has high reliability.

[0021] Furthermore, in step 5, the borehole data type is paleomagnetic data. When comparing and verifying paleomagnetic data with drilling data, the following method is specifically used:

[0022] 1) First, verify whether the paleomagnetic reversal boundary and the strong reflection phase axis of the shallow section have a good correspondence. The good correspondence means that the shallow section phase axis near the paleomagnetic change point on the shallow section can be continuously tracked in the horizontal direction; if the phase axis cannot be continuously tracked in the horizontal direction, it is considered that the two are not comparable, and recheck according to steps 1-4 to eliminate errors;

[0023] 2) Then carry out comparative verification of the main interfaces: based on the positions of the main interfaces provided by the traditional paleomagnetic interpretation, further comparative verification is carried out according to the shallow section profile. First, the positions of the main controlling interfaces B / M and M / G interfaces on the shallow section profile are determined. On the shallow section profile, obvious seismic phase changes appear on the B / M and M / G interfaces. Secondly, the secondary Blake and Jara event interfaces are determined. On the shallow section, the shallow section phase axis corresponding to the Blake event interface can be traced in the work area.

[0024] Furthermore, in step 3, when arranging the drilling data format, the seabed depth is uniformly added to the drilling data so that the starting depth of the drilling data is consistent with the seabed depth.

[0025] Furthermore, in step 2, the seabed depth H is determined by:

[0026] H=1.5*T S / 2

[0027] Among them, T S For a round trip on the shallow seabed.

[0028] Furthermore, in step 4, the drilling data is converted from depth to time in the following manner:

[0029] T=2*D / v

[0030] Where D is the depth of the borehole data, T is the round-trip travel time of the borehole data, and v is the average velocity.

[0031] Furthermore, when there are multiple types of drilling data, after step 5, a step of comprehensively comparing and verifying the multiple types of drilling data and the shallow profile joint interpretation results is also included.

[0032] Compared with the prior art, the advantages and positive effects of the present invention are:

[0033] This scheme changes the traditional method of analyzing shallow section and drilling data separately, and instead analyzes the two together, mutually verifying multiple drilling indicators (grain size, foraminifera, dating and paleomagnetism) with shallow section to minimize multi-solutions and improve the reliability of shallow section stratigraphic interpretation. This method has high practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the process of the shallow-profile well-seismic joint analysis method according to an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of loading shallow profile and drilling data and determining the seabed depth at the drilling site according to an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the combined interpretation of shallow profiling and dating after well-seismic calibration in an embodiment of the present invention;

[0037] Figure 4 This is a typical schematic diagram of traditional dating interpretation;

[0038] Figure 5 It is a schematic diagram of the combined interpretation of shallow profiling and grain size after well seismic calibration in an embodiment of the present invention;

[0039] Figure 6 It is a schematic diagram of shallow profiling and foraminifera joint interpretation after well-seismic calibration according to an embodiment of the present invention;

[0040] Figure 7 It is a schematic diagram of shallow profiling and paleomagnetic joint interpretation after well-seismic calibration in an embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of traditional paleomagnetic interpretation;

[0042] Fig. 9 It is a schematic diagram of the combined interpretation of shallow profiling and four indicators after well seismic calibration in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that well seismic generally refers to drilling and seismic, which is a more professional term in the industry. Seismic is a general term for single-channel seismic, shallow-profile seismic, multi-channel seismic, etc. In this solution, seismic specifically refers to shallow profile. In the following description, many specific details are explained to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0044] The present invention discloses a method for identifying and analyzing stratum structure based on shallow profile well-seismic combination. Figure 1 As shown, the following steps are included:

[0045] Step 1: Load shallow section data, where the shallow section coordinates loaded are coordinates representing the actual position;

[0046] Step 2: determine the drilling location and obtain the seabed depth according to the drilling location;

[0047] Step 3, data index selection and data format arrangement: determine the type of borehole data, and format the borehole data so that the starting depth of the borehole data is consistent with the seabed depth; the borehole data includes but is not limited to any one or more of dating data, grain size data, foraminifera data and paleomagnetic polarity data;

[0048] Step 4: Calibration of drilling data and shallow profile: The shallow profile coordinate is time, and the drilling data coordinate is depth. The drilling data is converted from depth to time to achieve matching between the two.

[0049] Step 5: Comparison and verification of drilling data and shallow sectioning;

[0050] Step 6: When there are multiple types of drilling data, a comprehensive comparison and verification can be performed on the multiple types of drilling data and the shallow profile joint interpretation results.

[0051] Specifically, the present invention is described in detail below in conjunction with specific embodiments:

[0052] Embodiment 1: In this embodiment, the borehole data type is selected as dating data. Taking dating data as an example, the shallow profile well-seismic combined dating analysis method is described in detail:

[0053] The biggest problem with dating is whether its results are reliable. The dating described in this embodiment includes C14 dating, OSL dating, ESR dating, etc. The technical methods are different, but the format of the final result is basically the same, that is, providing a dating year. Since there are many factors affecting the results of OSL dating, it is more likely to produce erroneous results, and it is most necessary to compare and verify with seismic profiles; for the sake of ease of understanding, this embodiment takes OSL dating as an example, combined with the characteristics of shallow seismic profiles, which is equivalent to adding a layer of constraints to the dating results, which can minimize the uncertainty of the dating age, specifically:

[0054] Step 1. Load shallow data

[0055] Loading shallow profile data is a routine operation process. It should be pointed out here that the loaded shallow profile coordinates must represent the coordinates of the actual position. Because for some equipment, especially old equipment, the shallow profile source is generally tens of meters behind the survey ship, there is a distance difference between it and the positioning equipment, and the acquisition system has not made relevant position corrections. At this time, manual position correction is required. The method of position correction has been disclosed in the invention patent "A method for removing abnormal fluctuations in dragged shallow profile formations" (authorization announcement number CN113189646B), and will not be repeated here.

[0056] Step 2. Determine the position of the drill hole in the profile and determine its depth

[0057] First, determine the drilling position, project the drilling position coordinates onto the shallow profile, and then obtain the shallow seabed depth based on the drilling position. The shallow seabed depth is:

[0058] H=1.5*T S / twenty one)

[0059] Where T S For a two-way trip with shallow seabed, H is the depth of shallow seabed. It should be pointed out that the field construction report of the drilling will also measure the water depth, but there may be a certain error between this data and the shallow seabed depth value (mainly due to tidal difference), and the seabed depth shall be based on the shallow seabed depth.

[0060] Step 3. Formatting the dating data

[0061] Whether it is C14 dating, OSL dating, or other dating, the data format is only a chronological data, so the dating data format is relatively simple, with three columns: well name, dating value, and depth. The starting point of the dating data is zero, indicating that it is measured from the seabed. In order to be consistent with the shallow profile data, its starting depth needs to be consistent with the seabed depth, that is, all dating polarity data need to be uniformly added with the seabed depth H.

[0062] Step 4. Calibration of dating data and shallow profile:

[0063] In this solution, the calibration principle of different borehole data and shallow profiles is the same. Generally, the shallow profile coordinate is time, and the dating (borehole data) coordinate is depth. The process of matching the two is called the calibration of borehole data and shallow profile, that is, establishing a one-to-one correspondence between the two. In this embodiment, the dating data is converted from depth to time, that is, the following is obtained:

[0064] T = 2*D / v (2)

[0065] Where D is the depth of the dating data, T is the round-trip travel time of the dating data. Since the shallow profiling detection depth is relatively shallow, the general detection depth is 60m below the seabed. The speed generally does not change much within this range, so v is generally 1500m / s.

[0066] Step 5. Comparison and verification of dating data and earthquakes

[0067] The late Pleistocene sediments are divided into five periods according to the sedimentary periods of deep-sea oceanic sediments, namely MIS5 (128ka-74ka), MIS4 (74ka-61ka), MIS3 (61ka-24ka), MIS2 (24ka-12ka) and MIS1 (12ka-present). MIS5 and MIS3 are mainly marine, and their typical characteristics are good stratification on seismic. Since the sea level in MIS5 is relatively high, the stratification is generally better than that in MIS3, and due to the long deposition time, its sediment thickness is generally greater than that in MIS3. The overall sea level in MIS3 is lower than that in MIS5, and it is more likely to have marine-continental alternation, that is, stratification and chaotic reflections alternate with each other. MIS2 and MIS4 are mainly continental deposits, and the typical characteristics on the seismic profile are the development of rivers, and the stratification of seismic sequences is often poor. According to the above seismic phase characteristics, they can be compared with the dating results. If the dating results are consistent with the seismic phase results, the dating results are considered to be relatively reliable, otherwise there must be problems with the dating results.

[0068] Specifically, the present embodiment generally divides the periods in order from top to bottom according to the dating results, that is, after dividing the depositional periods according to the dating results, observe whether the seismic phase characteristics in the divided depositional periods are consistent with the seismic phase characteristics of the theoretical depositional periods. If they are basically consistent, the next period is compared until all dating results are verified by seismic phase comparison. If only the dating of individual points does not match, its sudden factors may cause the dating results to be inaccurate, and it only needs to be simply discarded. If the dating results of a large number of dates do not match the earthquake, it is generally believed that there are serious problems with the dating results, and the reliability of the dating results needs to be reconsidered at this time.

[0069] The traditional analysis method has no reliable shallow subdivision interface constraints, so it is difficult to ensure the correctness of the analysis results. However, the reliability of the analysis results and the analysis efficiency of the present invention are greatly improved due to the relatively reliable constraints, as shown in the experimental verification part.

[0070] In Example 2, the granularity data is selected as the borehole data type. This example takes the granularity data as an example to explain in detail the shallow profile well-seismic combined granularity analysis method. The difference between this example and Example 1 mainly lies in the difference in the comparison and verification in step 5, or in the slight difference in data sorting, which is specifically described as follows:

[0071] In this embodiment, in step 3, when selecting granular data indicators and arranging data formats, the following method is adopted:

[0072] The particle size data of the borehole is currently mainly measured by a laser particle analyzer, which is generally sampled at equal intervals (e.g., 6 cm), and the sample length is generally 2 cm. The test results include sand content, silt content, clay content, median particle size, average particle size, sorting coefficient, skewness, peak state, etc. The above indicators are all used in traditional particle size analysis, but for the joint interpretation of wells and seismic, it is too complicated to conduct a joint interpretation of each indicator. In this embodiment, the average particle size is selected as the particle size data indicator to achieve a better joint analysis effect of wells and seismic. The average particle size is also easier to reflect the law of physical property changes during the joint interpretation of wells and seismic. The particle size data is based on the average particle size.

[0073] In addition, since the particle size measurement is measured at equal intervals, there are many missing data in the middle. In order to facilitate subsequent analysis, the missing data in the middle needs to be interpolated through the measured particle size data to obtain complete particle size data. In addition, the starting point of the particle size data is zero, indicating that it is measured from the seabed. In order to be consistent with the shallow profile data, as in Example 1, its starting depth also needs to be consistent with the seabed depth, that is, all particle size data need to be uniformly added with the seabed depth H.

[0074] In addition, when comparing and verifying the particle size and shallow profile in step 5, the following methods are used:

[0075] (1) Determination of important interfaces.

[0076] The interface on the shallow section is mainly the wave impedance interface, and its formula is

[0077]

[0078] Wherein ρ1 is the sediment density on the wave impedance interface, V1 is the sediment velocity on the wave impedance interface, ρ2 is the sediment density below the wave impedance interface, and V2 is the sediment velocity below the wave impedance interface. Since the shallow profiling detection depth is relatively shallow, the sediment velocity does not change much, which is basically 1500m / s. Therefore, the size of the wave impedance is mainly related to the density of the sediment above and below the wave impedance interface. Since the density of the sediment is positively correlated with the average particle size, the present invention uses the change of the average particle size to characterize the change of the wave impedance, thereby establishing the relationship between the shallow profiling and the particle size data, that is, the degree of change of the particle size data reflects the degree of change of the wave impedance.

[0079] When the average grain size is projected onto the shallow section according to Formula 2, the corresponding relationship between the grain size change and the shallow section can be intuitively seen. Taking the shallow section as the benchmark, the seismic layer interface of the shallow section interpretation is delineated, and the average grain size will change significantly at the interface. The average grain size change rate can be used to quantitatively calculate the degree of change in the average grain size, and the formula is:

[0080]

[0081] in is the average particle size change rate, is the previous average particle size, is the current average particle size.

[0082] According to experience, the ratio of the change rate of the average particle size at the interface to the change rate at the surrounding position is often more than 50%. This change is the change of physical properties and the change of sedimentary characteristics. If the particle size change near the sedimentary interface is not obvious or irregular (for example: the ratio of the change rate at the interface to the change rate at the surrounding position is 0-20%), it is necessary to check whether there is a problem with the drilling data or give other reasonable explanations. If most of the interfaces have obvious changes, but a few of the interfaces have no obvious changes, it is normal. Generally speaking, it is normal for the overall interpretation of the layer position and the average particle size change rate to reach 80%. If the match rate between the two is less than 60%, it needs to be re-verified, but this situation is a low-probability event. If the problem in the process is eliminated, specific problems need to be analyzed specifically, which will not be expanded here.

[0083] After the correspondence between the two is determined, the interface after joint interpretation can be used as an important basis for the core stratification plan. The core near the interface will also have obvious changes, such as color changes, bedding changes, biological activity changes, etc., which provides important basis and standards for the next step of comprehensive research.

[0084] (2) Analysis of particle size variation trend within the interface

[0085] When the important interfaces are determined, the particle size will also undergo certain periodic changes between the interfaces. There are three main situations: 1. The particle size data gradually increases, which generally reflects that the climate is gradually getting colder, the sea water is gradually retreating, and the sea level is lowering; 2. The particle size data does not change much, which generally reflects that the climate is relatively stable during this period and the sea level does not change much; 3. The particle size data gradually decreases, which generally reflects that the climate is gradually warming, sea water invades the land, and the sea level rises. The combination of increase, flatness and decrease in particle size data corresponds to the periodic cooling and warming of the climate.

[0086] Specifically, first determine the analysis scope according to the horizon divided by the result of well-seismic combination, this is because climate change can only be within a certain specific time range, and the interpretation result is meaningless if it is separated from the limitation of time range, and the time period represented by the horizon can be determined by methods such as geological age dating (embodiment 1), which will not be described in detail here. After determining the analysis scope, the granularity change cycle is delimited according to the specific circumstances of granularity change, and the granularity becomes larger and is represented by an ascending arrow, and the granularity decreases and is represented by a descending arrow, and the granularity change is not much, and then a horizontal arrow is used. It should be pointed out that the actual granularity change is relatively large, that is, the change of particle size is very frequent, and this is mainly related to part of the sudden sedimentary events (such as sudden debris flow), and the microclimate change time is relevant, and it can not represent the overall trend of climate change, therefore, when dividing granularity, it is necessary to be based on the overall change trend of granularity, and a small change trend should be abandoned. In addition, the granularity division near the interface position should be particularly noted, and the interface often means that the sedimentary discontinuity, that is, the sedimentary record is discontinuous, and the result of its division in this case is unreliable. After the granularity division is completed, the research contents such as climate change can be specifically analyzed according to the law of granularity change, which will not be described in detail here.

[0087] Example 3, foraminifera data is selected from the borehole data. This example takes foraminifera data as an example to explain in detail the shallow well seismic combined foraminifera analysis method. The difference between this example and Example 1 is mainly that the comparison and verification in step 5 is different, or there are slight differences in data sorting, specifically:

[0088] In step 3, the foraminifera data of the borehole is currently mainly obtained through manual observation. Depending on the purpose of the test, the sampling interval will also be quite different, generally between 8-30cm, and the sample length is generally 2cm. The test results include foraminifera abundance, simple differentiation, composite differentiation, and the percentage changes of the main foraminifera genera and species, such as A. beccarii vars, E. magellanicum, Stainforthia SP, N. jacksonensis, etc. Although different indicators can indicate different sedimentary environments, since the present invention mainly focuses on the innovation of the overall framework of well-seismic combination, it is impossible to carry out one by one for each specific indicator. This embodiment analyzes the well-seismic combination in detail for the most widely applicable foraminifera abundance indicator, and other indicators are roughly the same, and the present invention will not be described in detail.

[0089] Similarly, since foraminifera measurements are made at irregular intervals, there are many missing data in the middle. In order to facilitate subsequent analysis, the missing data in the middle need to be interpolated through the measured foraminifera data to obtain complete foraminifera data. In addition, the starting point of the foraminifera data is zero, indicating that it is measured from the seabed. In order to be consistent with the shallow profile data, its starting depth needs to be consistent with the seabed depth, that is, all foraminifera data need to be uniformly added with the seabed depth H.

[0090] In step 5, joint analysis of foraminiferal abundance and shallow profiling:

[0091] The abundance of foraminifera is closely related to the changes in marine and terrestrial phases. A high abundance of foraminifera reflects marine deposition, while the absence of foraminifera basically reflects terrestrial deposition. The higher the abundance of foraminifera, the more stable the marine deposition is. The lower the abundance of foraminifera, the less stable the marine deposition is. The joint analysis method with shallow profiling is as follows:

[0092] 1) First, group them according to the continuity of foraminifera abundance and preliminarily divide the marine and terrestrial phases. Continuous sedimentary combinations with zero foraminifera abundance are classified as terrestrial deposits, and the rest are marine deposits. When dividing, it is necessary to pay attention to the occurrence of abnormal points, such as the appearance of separate marine deposits in continuous terrestrial deposits or separate terrestrial deposits in continuous marine deposits. These are generally considered to be sudden unexpected situations and have no statistical significance in geological understanding. At this time, there is no need to give a certain explanation for everything, unless there are a large number of the same phenomenon or there is obvious evidence to support it, then a detailed division is required.

[0093] 2) Determination of the relationship between the marine and continental interface and the shallow profile wave impedance interface. Based on practical experience, the present invention proposes two ways of hard contact and soft contact foraminifera abundance changes. The so-called hard contact refers to the sudden change of foraminifera content at the marine and continental boundary, that is, it suddenly increases from zero in the continental phase to the maximum value, which is a landmark indicator of sedimentary discontinuity. In this case, the wave impedance interface often has a more obvious reflection phase axis corresponding to it. Soft contact refers to the slow change of foraminifera content at the marine and continental boundary, which often means that there is a connection between the marine and continental transition phases between the sea and the land. In this case, the change of the shallow profile seismic phase at the marine and continental interface often shows the characteristics of gradual change. In addition, the obvious boundary on the shallow seismic profile is not the boundary of the marine and continental phases indicated by the foraminifera abundance. This situation is mostly caused by the continental deposition sandwiched between two marine strata, while the continental geological history period is mainly dominated by erosion, and the continental strata cannot be deposited.

[0094] 3) Joint analysis of changes in marine and continental phases and shallow seismic phases within the interface. Generally, the marine and continental phases indicated by the abundance of foraminifera within the interface are highly correlated with the shallow seismic phases. Generally speaking, marine stratigraphic sediments are relatively continuous and have good seismic stratification, while continental seismic sediments are relatively messy and have poor seismic stratification. However, when the marine sediments are relatively stable and the seismic is non-stratified, that is, the seismic phase reflects a transparent reflection, this situation is also possible. Correspondingly, continental lake sediments also have good seismic stratification. However, generally speaking, the seismic phases within the interface indicated by the abundance of foraminifera are often consistent, and there are very few cases where the seismic phases show significant changes.

[0095] Through the previous joint analysis, in general, the overall interpreted strata and the marine-continental interface can be roughly consistent. After the corresponding relationship between the two is determined, the interface after joint interpretation can be used as an important basis for the core layering plan. The core near the interface will also have obvious changes, such as color changes, bedding changes, biological activity changes, etc., which provides an important basis and standard for the next step of comprehensive research.

[0096] Example 4, the borehole data selects paleomagnetic data. Taking paleomagnetic data as an example, the shallow profile well seismic combined paleomagnetic analysis method is described in detail. The difference between this example and Example 1 is mainly that the comparison and verification in step 5 is different, or there are slight differences in data sorting, specifically:

[0097] In step 3, when paleomagnetic polarity data format is organized, the paleomagnetic polarity data measurement results are divided into positive polarity data and negative polarity data, which can be arranged from top to bottom. Generally, the positive polarity is set to 1, which is a black polarity column, and the negative polarity is 0, which is a white polarity column. The starting point of the paleomagnetic polarity data is zero, indicating that it is measured from the seabed. In order to be consistent with the shallow profile data, its starting depth needs to be consistent with the seabed depth. Similarly, all paleomagnetic polarity data need to be uniformly added with the seabed depth H.

[0098] In step 5, when comparing and verifying paleomagnetic and shallow profile, the comparison of paleomagnetic measurement results with standard polarity columns is a traditional method, which will not be described in detail here. The present invention only makes further comparison and verification on its interpretation results. Its basic idea and principle is: on the whole, the location of paleomagnetic polarity change is closely related to sedimentary discontinuity, and sedimentary discontinuity generally corresponds to a stronger phase axis on the shallow profile. Therefore, there is a certain correspondence between paleomagnetic and shallow profile, which is the core of establishing a comparison and verification between the two. Specifically:

[0099] 1) First, verify whether the paleomagnetic reversal boundary and the strong reflection phase axis of the seismic profile have a good correspondence. This good correspondence means that on the seismic profile, the seismic profile phase axis near the paleomagnetic change point can be continuously tracked horizontally. If the phase axis cannot be continuously tracked horizontally, it is considered that the two are not comparable. At the same time, it should be pointed out that if it is a sudden sedimentary event (such as a sudden mudslide, etc.), it may cause paleomagnetic reversal, but this situation is not representative. In the interpretation process, reasonable choices can be made according to actual conditions. After actual inspection of multiple boreholes, in general, the degree of agreement between the two can reach more than 80%. If the two are not comparable as a whole, it is generally a problem with the previous process, and it is necessary to recheck according to steps 1-4 to eliminate errors.

[0100] 2) Secondly, conduct comparative verification of the main interfaces. Traditional paleomagnetic interpretation can provide the location of the main interfaces, and here we only conduct further comparative verification based on seismic profiles. First, determine the main controlling interfaces B / M and M / G interfaces, which are large interfaces of the same level.

[0101] According to the traditional law of paleomagnetic polarity, the B / M boundary is mainly composed of positive polarity columns, and the B / M boundary is mainly composed of negative polarity columns. The key point of its division is that it is sometimes difficult to determine its position, that is, it seems feasible to move the B / M boundary up or down, so its division has a certain degree of multi-solution. On the shallow profile, the B / M interface generally shows obvious seismic phase changes. For example, the stratification above the interface is better and the strata are more continuous, while the stratification below the interface is poor. There is often a clear contrast between the two, which can basically determine the B / M boundary. The M / G interface is similar to this, but most M / G interfaces are buried deeper and are generally less involved.

[0102] Secondly, determine the secondary Blake, Jara and other event interfaces. Taking the Blake event as an example, it is located above the B / M boundary and belongs to the negative polarity column in the positive polarity column. Its reversal scale is relatively small, but because there are also multiple reversal polarities above the B / M interface, the Blake event interface is also difficult to determine. In the shallow section, the seismic profile phase axis corresponding to the Blake event interface can often be traced in the work area, that is, its erosion surface distribution range is large, rather than a local small event, so the Blake event can be basically determined. The determination method of other event interfaces of the same level is similar, which will not be described in detail here.

[0103] Embodiment 5, the borehole data selects multiple types of paleomagnetic data, dating data, grain size data and foraminifera data. After the joint comparison and verification of each borehole data index and shallow profile, the joint interpretation results of each borehole data can be comprehensively compared and verified to improve the reliability of the analysis results and the uniqueness of the interpretation. For example, the results of Embodiments 1 to 4 can be comprehensively compared and verified in pairs, or the results of Embodiments 1 to 3 can be comprehensively compared and verified, or the results of Embodiments 1 to 4 can be comprehensively compared and verified. The more constraints there are, the more accurate the interpretation results will be.

[0104] Experimental verification:

[0105] The present invention takes the Yellow Sea Changshan Islands 1:50,000 marine regional geological survey project as an example to illustrate the method of the present invention:

[0106] 1. After loading the shallow profile data and the drilling location, obtain the seabed depth at the drilling location, such as Figure 2 As shown, the round trip travel time is 71 ms, and the depth of the borehole is 53.25 m according to Formula 1.

[0107] 2. Drilling data collation:

[0108] 2.1 The dating data are shown in Table 1. The depth unit is meter. It should be pointed out that the coordinate system is based on the sea surface, that is, the final data is the original depth plus the depth of the borehole, 53.25m. In fact, traditional dating can only provide the corresponding relationship between depth and dating. Due to the many factors affecting the dating results, its rationality needs to be further verified. However, there is no better way to verify the rationality of the traditional method except to believe in the dating results.

[0109] Table 1 Dating data format

[0110] well name Age at dating (ka) Depth(m) CSH01 21.52±1.37 56.45 CSH01 22.89±3.99 58.75 CSH01 31.62±6.52 63.43 CSH01 44.51±1.71 66.07 CSH01 52.32±4.13 69.92 CSH01 65.89±3.55 72.12 CSH01 68.17±6.62 75.55 CSH01 73.81±7.46 76.49 CSH01 95.35±5.12 82.82 CSH01 97.96±4.86 86.09

[0111] 2.2 Granularity Data Format Arrangement

[0112] According to the laser test method, the average particle size data is obtained, as shown in Table 2 on the left, it can be seen that the sampling length is 2cm and the sampling interval is about 22cm. The top depth and bottom depth units are centimeters. The average particle size at the interval sampling position is interpolated by the average particle size at the sampling position, and the depth of 53.25m at the drilling hole is added. The data format after sorting is shown in Table 2 on the right, where the top and bottom depth units are meters.

[0113] Table 2 Average particle size data and format arrangement (left: original data; right: arranged data)

[0114]

[0115] 2.3 Foraminifera abundance data format

[0116] According to the test, the foraminifera abundance data is obtained, as shown in Table 3 on the left. It can be seen that the sampling length is 2 cm and the sampling interval is about 24 cm. The top depth and bottom depth units are centimeters. The foraminifera abundance at the interval sampling position is interpolated by the foraminifera abundance at the sampling location, and the depth of 53.25m at the borehole is added. The format of the data after sorting is shown in Table 3 on the right, where the top and bottom depth units are meters.

[0117] Table 3 Foraminifera abundance data and format arrangement (left: original data; right: arranged data)

[0118]

[0119] 2.4 Paleomagnetic data formatting

[0120] The polarity data of paleomagnetic measurement are shown in Table 4. The top depth and bottom depth are in meters, and 1 represents positive polarity and 0 represents negative polarity. It should be pointed out that the coordinate system is based on the sea surface, that is, the final data is the original depth plus the depth of the borehole, 53.25m.

[0121] Table 4 Paleomagnetic data format

[0122]

[0123] 3. After well seismic calibration, the borehole data can be combined with the shallow profile for comparative verification;

[0124] (1) Taking dating as an example, Figure 3As shown in the figure, according to the interpretation results of the seismic profile, the seismic sequence is divided as shown in the white box. The dating results of 21.52±1.37ka and 22.89±3.99ka are basically in the MIS2 period, and the sedimentary wave groups are obviously more chaotic, which corresponds well to the fluvial phase deposition in this period; the dating results of 31.62±6.52ka and 44.51±1.71ka are basically in the MIS3 period. It can be seen that the chaotic reflection and stratified reflection of the sedimentary strata in this period appear periodically, which is related to the ups and downs of the sea level in the MIS3 period, and the dating results are relatively reasonable; the MIS5 period shows obvious stratification characteristics on the seismic profile, indicating that the sea level in this period is high and the sedimentation is very stable. The sedimentary period is roughly between 76-120ka, but the dating results are far less than this value. There is a fatal error in the dating results, that is, the dating data after 52.32±4.13ka is unavailable.

[0125] Traditional methods of interpreting dating results lead to completely different conclusions that are meaningless. Figure 4 ) is simply combined with the lithological profile and cannot verify the reliability of the dating results at all.

[0126] (2) Taking grain size data as an example, after well seismic calibration, the grain size data can be combined with the shallow profile, such as Figure 5 As shown, the mutation point of the calibrated particle size ( Figure 5 The position (indicated by the horizontal arrow on the left side of the borehole) basically shows a one-to-one correspondence with the shallow-section strong wave impedance interface, indicating that the calibrated data has a high reliability. At the same time, it can be seen that the grain size data shows obvious periodic cyclic changes between the strong wave impedance interfaces. This change is consistent with the periodic changes in sea level, which lays the foundation for the next step of in-depth sedimentary evolution analysis.

[0127] (3) Taking foraminifera as an example, after well-seismic calibration, the foraminifera data can be combined with the shallow profile, such as Figure 6 After calibration, the mutation point of foraminifera is in good agreement with the shallow strong wave impedance interface. At the same time, the correspondence between sedimentary discontinuity, marine and continental phase changes and shallow seismic phases is also in good agreement, indicating that the data after calibration is highly reliable.

[0128] (4) Taking paleomagnetism as an example, the mutation points of paleomagnetism after calibration (such as Figure 7 The position of the borehole (indicated by the horizontal arrow on the left side) basically shows a one-to-one correspondence with the shallow profile strong wave impedance interface, indicating that the data after calibration is highly reliable. The traditional paleomagnetic interpretation results are shown in the figure, such as the Blake negative polarity and the B / M interface. With the constraints of the shallow profile and further verification, the conclusions can basically be changed from speculation to reliability. The traditional paleomagnetic interpretation ( Figure 8) is only compared with the standard polarity column. In this area, the sea and land changes are drastic, and the sedimentation is complex and changeable. It is difficult to get reliable conclusions from the comparison of their interfaces, and the conclusions are often inferred.

[0129] (5) A comprehensive comparison was made between the four types of drilling data and the combined analysis results of the shallow profile. Fig. 9 As shown in the figure, it is equivalent to adding four constraints, and the interpretation results are more reliable. In specific work, the four types of drilling data can also be compared and verified with the interpretation results of shallow section by pairwise integration, so that the reliability of the analysis results and the analysis efficiency can be greatly improved.

[0130] The above conclusions verify the effectiveness of the method of the present invention. The previous analysis methods had no reliable constraints on the shallow subdivision interface, so it was difficult to analyze the changing rules in detail, and even the analysis results were often wrong. However, the reliability of the analysis results and the analysis efficiency of this embodiment are greatly improved due to the relatively reliable constraints. The advantage of this joint interpretation is not available in traditional interpretation methods.

[0131] In addition, it should be noted that the present invention is designed to break the traditional method and thinking, and the process of this solution is gradually improved on the basis of constantly solving errors and problems. For example, in the early stage, the well-seismic data could not correspond at all, and the gap between the two was huge. It was even suspected that the well-seismic combination was not suitable for shallow profiling, that is, the two could only achieve a fuzzy correspondence, and could not achieve a one-to-one correspondence. The geological factors that could not correspond between the two were even constantly analyzed. Later, experts in various aspects such as shallow profiling acquisition, data processing, and drilling were combined to check possible problems one by one. After rigorous demonstration, better results of well-seismic combination were finally obtained. For example, a series of solutions for obtaining the depth of the seabed and the format of dating data were actually gradually matured on the basis of solving the problems one by one. It was based on the detailed demonstration of the above specific steps that better well-seismic combination results were finally obtained.

[0132] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for identifying and analyzing stratum structure based on shallow profile well-seismic combination, characterized in that: The following steps are involved: Step 1: Load shallow section data, where the shallow section coordinates loaded are coordinates representing the actual position; Step 2: determine the drilling location and obtain the seabed depth according to the drilling location; Step 3, data index selection and data format arrangement: determine the type of borehole data and format the borehole data; the borehole data includes but is not limited to any one or more of dating data, grain size data, foraminifera data and paleomagnetic polarity data; Step 4, calibration of drilling data and shallow profile: the shallow profile coordinate is time, the drilling data coordinate is depth, and the drilling data is converted from depth to time to achieve matching between drilling data and shallow profile; Step 5: Based on the characteristics of drilling data, realize the comparison and verification of drilling data and shallow section.

2. The method for identifying and analyzing stratum structure based on shallow-profile well-seismic combination according to claim 1 is characterized by: In step 5, the type of borehole data is dating data, and the comparison and verification between dating data and earthquake data is carried out in the following manner: According to the dating results, the sedimentary periods are divided in order from top to bottom, and the seismic phase characteristics within the divided sedimentary periods are observed to see whether they are consistent with the seismic phase characteristics of the theoretical sedimentary periods; if they are consistent, the next sedimentary period is compared until all the dating results are verified by seismic phase comparison; if individual dating results are inconsistent, they are discarded; if a large number of dating results are inconsistent with the seismic phases, the reliability of the dating results is poor and needs to be re-compared and verified.

3. The method for identifying and analyzing stratum structure based on shallow profile well-seismic combination according to claim 1 is characterized by: In step 5, the drilling data type is particle size data, and the average particle size is used as the particle size data indicator. When comparing and verifying the particle size with the shallow profile data, the following method is specifically used: (1) Determine the important interface: Use the change of average grain size to characterize the change of wave impedance, so as to establish the corresponding relationship between shallow section and grain size data, and use the shallow section as the benchmark to delineate the seismic layer interface of shallow section interpretation; (2) Analysis of the trend of particle size changes within the interface: the combination of increase, stability and decrease in particle size data corresponds to the periodic cooling and warming of the climate; (3) The analysis scope is determined by dividing the layers according to the results of the well-seismic combination, and the grain size change period is divided according to the grain size change. The relationship between the location of the grain size mutation point and the important interface is determined according to the law of grain size change. If there is a one-to-one correspondence, it means that the grain size data results are highly reliable.

4. The method for identifying and analyzing stratum structure based on shallow profile well-seismic combination according to claim 1 is characterized by: In step 5, the type of the borehole data is foraminifera data, and foraminifera abundance is used as the foraminifera data indicator. The joint analysis process of foraminifera abundance and shallow profile is as follows: (1) According to the continuity of foraminifera abundance, the marine and terrestrial facies were preliminarily divided into groups: the continuous sedimentary assemblages with zero foraminifera abundance were classified as terrestrial deposits, and the rest were marine deposits; (2) Determine the relationship between the marine-continental interface and the shallow profile impedance interface: define the hard contact and soft contact of foraminiferal abundance changes. The hard contact refers to the sudden change of foraminiferal content at the marine-continental boundary, and the soft contact refers to the slow change of foraminiferal content at the marine-continental boundary. (3) Joint analysis of the changes in marine and continental phases and shallow seismic phases within the interface: If the seismic phases within the interface indicated by the foraminifera abundance are consistent, and the position of the foraminifera mutation point is consistent with the shallow strong wave impedance interface, and there is a corresponding relationship between sedimentary discontinuities, marine and continental phase changes and shallow seismic phases, it indicates that the calibrated data has high reliability.

5. The method for identifying and analyzing stratum structure based on shallow profile well-seismic combination according to claim 1 is characterized by: In step 5, the borehole data type is paleomagnetic data. When comparing and verifying paleomagnetic data with drilling data, the following method is specifically used: 1) First, verify whether the paleomagnetic reversal boundary and the strong reflection phase axis of the shallow section have a good correspondence. The good correspondence means that the shallow section phase axis near the paleomagnetic change point can be continuously tracked in the horizontal direction on the shallow section; if the phase axis cannot be continuously tracked in the horizontal direction, it is considered that the two cannot be compared; 2) Then conduct comparative verification of the main interfaces: Based on the positions of the main interfaces provided by traditional paleomagnetic interpretation, further comparative verification is carried out according to the shallow section profile. First, the positions of the main controlling interfaces B / M and M / G interfaces on the shallow section profile are determined. On the shallow section profile, the B / M interface and the M / G interface show obvious seismic phase changes; Secondly, the secondary Blake and Jara event interfaces are determined. On the shallow section, the shallow section event axes corresponding to the Blake event interface can be traced in the work area.

6. The method for identifying and analyzing stratum structure based on shallow profile well-seismic combination according to claim 1 is characterized by: In step 3, when arranging the drilling data format, the seabed depth is uniformly added to the drilling data so that the starting depth of the drilling data is consistent with the seabed depth.

7. The method for identifying and analyzing stratum structure based on shallow profile well-seismic combination according to claim 1 is characterized by: In step 2, the seabed depth H is determined by: H=1.5*T S / 2 Among them, T S For a round trip on the shallow seabed.

8. The method for identifying and analyzing stratum structure based on shallow profile well-seismic combination according to claim 1 is characterized by: In step 4, the drilling data is converted from depth to time in the following manner: T=2*D / v Where D is the depth of the borehole data, T is the round-trip travel time of the borehole data, and v is the average velocity.

9. The method for identifying and analyzing stratum structure based on shallow profile well-seismic combination according to claim 1 is characterized by: When there are multiple types of drilling data, after step 5, the method further includes a step of comprehensively comparing and verifying the multiple types of drilling data and the shallow profile joint interpretation results.

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