Continental delta lake shoreline identification method and system

Abstract

The invention discloses a continental delta lake shoreline identification method and a continental delta lake shoreline identification system, which relate to the technical field of petroleum and natural gas geological exploration and are characterized in that a logging curve is calibrated by using a core observation result through combination of geology and geophysics so as to calibrate three-dimensional seismic data information; the development characteristics and the accurate position of the lake shoreline are comprehensively determined on a single well, a section and a plane, the applicability and the practicability are higher, and a reliable basis is provided for predicting sand body distribution of an estuary dam and an underwater diversion river channel. Starting from three aspects of core observation, logging curve analysis and three-dimensional seismic interpretation result analysis, the sedimentary facies type and the conversion interface thereof are effectively determined, so that the evolution history and the lake shoreline position of the continental facies delta overwater and underwater sedimentary environment are accurately revealed, important and accurate geological information is provided for lithologic oil and gas reservoir exploration, and the research and development of the continental facies delta is facilitated. The problem of low identification precision in the prior art is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum and natural gas geological exploration, and relates to a method and system for identifying a continental delta lake shoreline. Background Art

[0002] In recent years, with the deepening of geological exploration of oil and gas basins, the direction of oil and gas exploration has shifted from structural oil and gas reservoirs to lithologic oil and gas reservoirs. The vicinity of the lakeshore is a favorable phase zone for the development of lithologic oil and gas reservoirs. Due to the influence of the coastal current, the lakeshore plays an important role in controlling the distribution of lithologic stratigraphic traps, which is mainly reflected in the following four aspects: 1) The location and migration of the ancient lakeshore control the distribution and vertical stacking style of sand bodies; 2) The ancient lakeshore controls the formation and development of high-quality reservoirs. Generally, the reservoir properties of underwater sand bodies are better than those of above-water sand bodies; 3) The frequent migration of the ancient lakeshore provides good sedimentary conditions for the formation of reservoir-caprock combinations; 4) The vicinity of the ancient lakeshore is a favorable zone for the development of lithologic oil and gas reservoirs, and the oil and gas reservoirs are distributed in a skirt-like manner along the ancient lakeshore.

[0003] Core observation can most intuitively determine the sedimentary characteristics of the strata, thereby analyzing the sedimentary environment of the study area during the sedimentary period. Through the observation and analysis of core samples, the characteristics and composition of underground rocks can be directly obtained, including rock color, particle size, rock density, mineral composition, etc. This information can be used to determine geological characteristics such as rock type and rock structure. Bottom scouring, climbing sand ripple bedding, parallel bedding, plate-like cross-bedding, small trough-like cross-bedding, freshwater snail fossils and charcoal fragments are developed on the core, all of which appear in the continental delta environment. Core observation can also be used to verify seismic interpretation results.

[0004] Well logging curves are obtained by measuring changes in the physical properties of underground rocks, such as resistivity, natural gamma radiation, and acoustic wave velocity. Changes in these physical properties can be associated with different sedimentary phases, thereby identifying sedimentary phases. Usually, based on the analysis of multiple data such as cores and well logging, the morphological characteristics of well logging curves corresponding to the underwater distributary channels and estuary bar deposits at the delta front are summarized by using the changing characteristics of the morphology and amplitude of well logging curves such as natural potential, natural gamma, resistivity, and acoustic wave time difference.

[0005] Synthetic records and attribute slices in seismic exploration are two commonly used processing and analysis methods. They can be generated by simulating the reflection, refraction and scattering of seismic waves during underground propagation, and can be used to interpret the stratigraphic reflection characteristics in actual seismic records. Three-dimensional seismic records can provide higher-resolution stratigraphic information, helping researchers understand the changes in underground stratigraphic structure and sedimentary environment. Correcting the time and amplitude in actual seismic records has an outstanding effect on improving the accuracy of seismic interpretation and seismic imaging; slices along the amplitude can be compared and comprehensively analyzed with other seismic interpretations and geological data to provide more comprehensive geological interpretation and sedimentary environment reconstruction information. Some scholars have used three-dimensional seismic data to carry out detailed characterization of sedimentary facies, mainly including: based on core observation, through the extraction of seismic attributes, detailed characterization of the planar distribution characteristics of the delta plain subfacies and the delta front subfacies; using the three-dimensional Wheeler transform technology to automatically flatten the seismic phase axes of the high-resolution sequence stratigraphic framework, extract chronostratigraphic slices with isochronous significance, and conduct underwater delta front subfacies analysis; using the combined well-seismic method to provide assistance in the identification and interpretation of underwater distributary channels at the delta front.

[0006] Some scholars have studied the restoration of ancient lake shorelines. The application publication number CN112394400A, "A quantitative prediction method, equipment and system for ancient lake shorelines", provides a method for predicting the distribution of lake shorelines based on core observation results. However, this method only uses core data, and does not use seismic, well logging and other data, so the restoration results are not accurate enough. The article "Method for Distinguishing the Position of Ancient Lake Shorelines and Ancient Deep Lake Lines in Depression Lake Basins" takes the Chang 6 oil layer group of the late Triassic Yanchang period in the Ordos Basin as an example, using cores, well logging, field profiles and other data to systematically analyze and judge the formation mechanism and identification characteristics of various typical signs such as sedimentary structures, rock colors, cycles, fossils, etc. near the location of lake shorelines and deep lake lines, but the prediction accuracy of ancient lake shorelines is still low. The article "A method for rapid identification of deltaic shores under the background of multi-well aneismic data" used core phase and sedimentary cycle analysis, combined with the determination of steep slope mutation zones of inter-layer thickness markers, to identify the shoreline of the Chang 6 oil layer group in the Ansai Oilfield in the Ordos Basin. However, this method only analyzed sedimentary characteristics such as core data, sedimentary phases, and sedimentary cycles, and did not analyze the location of the ancient shoreline in combination with three-dimensional seismic data. The article "Identification of ancient shorelines and their control on sand bodies and oil and gas" used multiple identification marks such as geomorphic characteristics, special lithology, paleontological characteristics, sedimentary structures, geochemical indicators, and sedimentary phase changes to restore the shoreline, but the accuracy was low and the operability was poor. Summary of the invention

[0007] The purpose of the present invention is to solve the problem of low accuracy and poor operability of the ancient lake shoreline identification method in the prior art, and to provide a terrestrial delta lake shoreline identification method and system.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention proposes a method for identifying a continental delta lake shoreline, comprising the following steps:

[0010] Obtain the core and well logging curve of the selected well on the continental delta; determine the position of the sedimentary phase transition interface on the core based on the lithology of the core; calibrate the transition interface position of the well logging curve based on the transition interface position of the sedimentary phase on the core;

[0011] A plurality of seismic profiles are obtained through three-dimensional seismic records including the selected well; the seismic profile passing through the selected well is calibrated according to the position of the sedimentary phase conversion interface in the well logging curve to obtain the position of the sedimentary phase conversion interface of the selected well in the seismic profile;

[0012] Based on the position of the selected well sedimentary phase conversion interface on the seismic section, the isotropic axis of the selected well conversion interface on the seismic section is obtained, and the isotropic axis on the seismic section is traced laterally to obtain the shoreline point corresponding to the seismic section;

[0013] Based on the position of the iso-axis on the seismic section, the iso-axis corresponding to the sedimentary phase transition interface in the remaining seismic sections is calibrated, and the remaining iso-axis is traced laterally to obtain the shoreline points corresponding to the remaining seismic sections;

[0014] Based on the shoreline points corresponding to the seismic profile and the shoreline points corresponding to the remaining seismic profiles, the amplitude slices along the same axis are extracted to obtain the final distribution of the lake shoreline on the plane, thereby realizing accurate identification of the lake shoreline.

[0015] Preferably, the method for correctly calibrating the conversion interface position of the logging curve is as follows:

[0016] At the transition interface, if the natural potential curve of the sand body transitions from a funnel shape to a bell shape, the transition position between the funnel shape and the bell shape is the correct calibration position.

[0017] Preferably, the method for correctly selecting the isotropic axis on the seismic section is as follows:

[0018] On the seismic section, if the iso-axis on the seismic section has a lens-shaped reflection feature above and a progradational reflection feature below, the correct iso-axis is obtained.

[0019] Preferably, during the lateral tracking process, the point where the amplitude of the same-direction axis is lower than a preset value is the shoreline point.

[0020] Preferably, the lateral tracking adopts an automatic tracking method or a manual tracking method.

[0021] Preferably, locations along the layer amplitude slice where the amplitude is lower than a preset value constitute the lake shoreline.

[0022] Preferably, the iso-axis on the remaining seismic sections does not pass through the selected well, and the iso-axis on the remaining seismic sections is parallel to the iso-axis on the seismic section passing through the selected well.

[0023] Preferably, the lithology above the conversion interface is gray-green mudstone, gray-black carbonaceous mudstone or thin-layer fine sandstone; and the lithology below the conversion interface is gray-white thick-layer siltstone.

[0024] Preferably, the number of selected wells is positively correlated with the accuracy of lakeshore restoration results.

[0025] The present invention proposes a system for identifying the shoreline of a continental delta, comprising:

[0026] A first position information acquisition module, the first position information acquisition module is used to obtain the core of the selected well on the continental delta and the well logging curve of the selected well; determine the position of the sedimentary phase conversion interface on the core based on the lithology of the core; calibrate the conversion interface position of the well logging curve based on the conversion interface position of the sedimentary phase on the core;

[0027] A second position information acquisition module, the second position information acquisition module is used to obtain a plurality of seismic profiles through three-dimensional seismic records containing the selected well; calibrate the seismic profile passing through the selected well according to the position of the sedimentary phase conversion interface in the well logging curve, and obtain the position of the sedimentary phase conversion interface of the selected well in the seismic profile;

[0028] A seismic profile shoreline point acquisition module, which is used to acquire the isotropic axis of the selected well conversion interface on the seismic profile based on the position of the selected well sedimentary phase conversion interface on the seismic profile, and to laterally track the isotropic axis on the seismic profile to acquire the shoreline point corresponding to the seismic profile;

[0029] A module for acquiring shoreline points of the remaining seismic profiles, the module for acquiring shoreline points of the remaining seismic profiles being used to calibrate the iso-axis corresponding to the sedimentary phase transition interface in the remaining seismic profiles based on the position of the iso-axis on the seismic profiles, and to perform transverse tracking on the remaining iso-axis to acquire shoreline points corresponding to the remaining seismic profiles;

[0030] A shoreline point information processing module is used to extract the amplitude slices along the same axis based on the shoreline points corresponding to the seismic profile and the shoreline points corresponding to the remaining seismic profiles, obtain the final distribution of the lake shoreline on the plane, and realize accurate identification of the lake shoreline.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention proposes a method for identifying the shoreline of a continental delta. By combining geology with geophysics, the core observation results are used to calibrate the well logging curve, and then the seismic data are calibrated to comprehensively determine the development characteristics and accurate position of the shoreline in a single well, profile and plane. It has stronger applicability and practicality, and provides a reliable basis for predicting the distribution of sand bodies in estuary bars and underwater diversion channels. Starting from core observation, well logging curve analysis, and seismic interpretation results analysis, the sedimentary phase type and conversion interface are effectively determined, thereby accurately revealing the evolution history of the above-water and underwater sedimentary environments of the continental delta and the location of the shoreline, providing important and accurate geological information for the exploration of lithological oil and gas reservoirs, thereby solving the problem of low identification accuracy of the existing technology.

[0033] Furthermore, the higher the lateral tracking accuracy, the higher the accuracy of lake shoreline identification.

[0034] Furthermore, the number of selected wells is positively correlated with the lakeshore restoration results. There is no limit to the number of selected wells. The more wells are selected, the richer the core data and logging data are, and the more accurate the lakeshore restoration results are.

[0035] The present invention proposes a continental delta lake shoreline identification system, which realizes the continental delta lake shoreline identification by dividing the system into a first position information acquisition module, a second position information acquisition module, a seismic profile shoreline point acquisition module, a remaining seismic profile shoreline point acquisition module and a shoreline point information processing module. The modular concept is adopted to make each module independent of each other, which is convenient for unified management of each module. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A flow chart of the method for identifying the lakeshore of a continental delta provided by the present invention;

[0038] Figure 2 A schematic diagram of the position of the sedimentary phase transition interface on the core of the well selected for the present invention;

[0039] Figure 3 A schematic diagram of the conversion interface position of the well logging curve calibrated based on the conversion interface position of the core according to the present invention;

[0040] Figure 4 A schematic diagram of a seismic profile of a selected well of the present invention;

[0041] Figure 5This is a schematic diagram of the lake shoreline finally identified by the present invention.

[0042] Figure 6 This is a system diagram for identifying the lakeshore of a continental delta provided by the present invention.

[0043] Among them: 1-sedimentary phase transition interface on the core; 2-conversion interface of the logging curve; 3-funnel shape; 4-bell shape; 5-natural potential curve; 6-sedimentary phase transition interface of the selected well; 7-position of the shoreline point on the seismic profile passing through the selected well; 8-progradation reflection; 9-lenticular reflection; 10-delta plain; 11-delta front; 12-selected well; 13-lake shoreline; 14-seismic profile where the selected well is located; 15-remaining seismic profiles. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0047] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0048] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0049] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0051] The present invention proposes a method for identifying the shoreline of a continental delta. Figure 1 As shown, the following steps are included:

[0052] S1. Obtain the core and logging curve of the selected well on the continental delta; determine the position of the sedimentary phase conversion interface on the core based on the lithology of the core; calibrate the conversion interface position of the logging curve based on the conversion interface position of the sedimentary phase on the core;

[0053] The method to correctly calibrate the conversion interface position of the logging curve is as follows:

[0054] At the transition interface, if the natural potential curve of the sand body transitions from a funnel shape to a bell shape, the transition position between the funnel shape and the bell shape is the correct calibration position.

[0055] The lithology above the transition interface is gray-green mudstone, gray-black carbonaceous mudstone or thin-layer fine sandstone, representing an above-water sedimentary environment; the lithology below the transition interface is gray-white thick-layer siltstone, representing an underwater sedimentary environment.

[0056] S2. Obtaining a plurality of seismic profiles through three-dimensional seismic records including the selected well; calibrating the seismic profile passing through the selected well according to the position of the sedimentary phase conversion interface in the well logging curve, and obtaining the position of the sedimentary phase conversion interface of the selected well in the seismic profile;

[0057] S3, based on the position of the selected well sedimentary phase conversion interface on the seismic section, obtaining the isotropic axis of the selected well conversion interface on the seismic section, tracing the isotropic axis on the seismic section laterally, and obtaining the shoreline point corresponding to the seismic section;

[0058] The correct method for selecting the isotropic axis on the seismic section is as follows:

[0059] On the seismic section, if the iso-axis on the seismic section has a lens-shaped reflection feature above and a progradational reflection feature below, the correct iso-axis is obtained.

[0060] S4. Calibrate the iso-axis corresponding to the sedimentary phase transition interface in the remaining seismic sections based on the position of the iso-axis on the seismic section, and laterally track the remaining iso-axis to obtain the shoreline points corresponding to the remaining seismic sections;

[0061] During the lateral tracking process, the point where the amplitude of the same-direction axis is lower than the preset value is the shoreline point.

[0062] Lateral tracking uses automatic tracking methods or manual tracking methods.

[0063] The iso-axis on the remaining seismic sections does not pass through the selected well, and the iso-axis on the remaining seismic sections is parallel to the iso-axis on the seismic section passing through the selected well.

[0064] S5. Based on the shoreline points corresponding to the seismic profile and the shoreline points corresponding to the remaining seismic profiles, the amplitude slices along the same axis are extracted to obtain the final distribution of the lake shoreline on the plane, so as to realize the accurate identification of the lake shoreline.

[0065] The locations along the layer amplitude slice where the amplitude is lower than the preset value constitute the lake shoreline.

[0066] The number of selected wells is positively correlated with the accuracy of the lakeshore restoration results, that is, the number of selected wells is not limited. The more wells are selected, the richer the core data and logging data are, and the more accurate the lakeshore restoration results are.

[0067] The detailed steps of the identification method proposed by the present invention are as follows:

[0068] Step 1: Obtain the core of the selected well on the continental delta and obtain the well logging curve of the selected well;

[0069] Step 2: Determine the position of the transition interface of the sedimentary phase on the core based on the lithology of the core;

[0070] like Figure 2 and Figure 3 As shown, the location depth of the conversion interface is 2270m;

[0071] It should be noted that the conversion interface of the present invention is the conversion interface from the above-water deposition environment to the underwater deposition environment.

[0072] The position of the conversion interface of the core is determined based on the geological phenomenon that the lithology above the conversion interface is gray-green mudstone, gray-black carbonaceous mudstone and thin-layer fine sandstone; the lithology below the conversion interface is gray-white thick-layer siltstone.

[0073] Step 3: Calibrate the conversion interface position of the logging curve based on the conversion interface position of the core;

[0074] Verify whether the conversion interface position of the logging curve is calibrated correctly:

[0075] At the transition interface, if the natural potential curve transitions from a funnel shape to a bell shape, the transition position is the correct position of the sedimentary phase transition interface.

[0076] Step 4: Obtain several seismic profiles through the 3D seismic records containing the selected wells, such as Figure 4 As shown;

[0077] Step 5: calibrate the seismic section passing through the selected well according to the position of the sedimentary phase conversion interface in the well logging curve to obtain the position of the sedimentary phase conversion interface of the selected well in the seismic section;

[0078] Based on the position of the selected well sedimentary phase conversion interface on the seismic section, the isotropic axis of the selected well conversion interface on the seismic section is obtained, and the isotropic axis on the seismic section is laterally traced to obtain the shoreline point corresponding to the seismic section;

[0079] Verify that the co-directional axis is selected correctly:

[0080] On the seismic section, if the iso-axis has a lens-shaped reflection feature above and a progradational reflection feature below, it means that the iso-axis is correctly selected.

[0081] Step 6: based on the position of the isotropic axis in step 5, the isotropic axis of the remaining seismic profiles is calibrated; and the remaining isotropic axis is horizontally tracked to obtain the shoreline points corresponding to the remaining seismic profiles;

[0082] In the process of lateral tracking in steps 5 and 6, the point where the amplitude of the same-direction axis is lower than the preset value is the shoreline point (that is, the point where the same-direction axis changes in strength is the shoreline point).

[0083] The lateral tracking in step 5 adopts an automatic tracking method or a manual tracking method;

[0084] The lateral tracking in step 6 adopts an automatic tracking method or a manual tracking method.

[0085] The iso-axis of the remaining seismic sections does not pass through the selected well, and the iso-axis of the remaining seismic sections is parallel to the iso-axis in step 5.

[0086] Step 7: Extract the amplitude slices along the layer based on the iso-axis calibrated in steps 5 and 6 to obtain the final lake shoreline, such as Figure 5 shown.

[0087] The position where the amplitude of the layer amplitude slice is lower than the preset value constitutes the lake shoreline (that is, the position where the amplitude attribute of the layer amplitude slice changes significantly in strength on the slice is the lake shoreline).

[0088] The basis for determining that the study area is a continental delta is that the deposition period was an overcompensated shallow open-flow lake basin;

[0089] Seismic reflection features include blank reflections, lenticular and foreset reflection features;

[0090] The natural potential shapes in the well logging curve include bell shape and funnel shape;

[0091] The core is developed with bottom scour, climbing sand ripple bedding, parallel bedding, plate-like cross-bedding, small-scale trough cross-bedding, freshwater snail fossils and charcoal fragments.

[0092] The present invention proposes a system for identifying the shoreline of a continental delta. Figure 6 As shown, it includes a first position information acquisition module, a second position information acquisition module, a seismic profile shoreline point acquisition module, a remaining seismic profile shoreline point acquisition module and a shoreline point information processing module;

[0093] The first position information acquisition module is used to obtain the core of the selected well on the continental delta and the well logging curve of the selected well; determine the position of the sedimentary phase conversion interface on the core based on the lithology of the core; calibrate the conversion interface position of the well logging curve based on the conversion interface position of the sedimentary phase on the core;

[0094] The second position information acquisition module is used to obtain a number of seismic profiles through the three-dimensional seismic records containing the selected well; calibrate the seismic profile passing through the selected well according to the position of the sedimentary phase conversion interface in the well logging curve, and obtain the position of the sedimentary phase conversion interface of the selected well in the seismic profile;

[0095] The seismic profile shoreline point acquisition module is used to acquire the isotropic axis of the selected well conversion interface on the seismic profile based on the position of the selected well sedimentary phase conversion interface on the seismic profile, and to laterally track the isotropic axis on the seismic profile to acquire the shoreline point corresponding to the seismic profile;

[0096] The shoreline point acquisition module of the remaining seismic profile is used to calibrate the iso-axis corresponding to the sedimentary phase transition interface in the remaining seismic profile based on the position of the iso-axis on the seismic profile, and to laterally track the remaining iso-axis to obtain the shoreline point corresponding to the remaining seismic profile;

[0097] The shoreline point information processing module is used to extract the amplitude slices along the same axis based on the shoreline points corresponding to the seismic profile and the shoreline points corresponding to the remaining seismic profiles, obtain the final distribution of the lake shoreline on the plane, and realize accurate identification of the lake shoreline.

[0098] Therefore, the present invention proposes a method for identifying the lakeshore of a continental delta. By combining geology with geophysics, the core observation results are used to calibrate the well logging curve, and then the seismic data is calibrated to comprehensively determine the development characteristics and accurate position of the lakeshore in a single well, profile and plane. It has stronger applicability and practicality, and provides a reliable basis for predicting the distribution of sand bodies in estuary bars and underwater diversion channels. Compared with the prior art, the present invention discloses a method for identifying the lakeshore of a continental delta, which can accurately obtain the location of the lakeshore by combining core observation, well logging curve analysis and seismic interpretation. Starting from the three aspects of core observation, well logging curve analysis and seismic interpretation results analysis, the sedimentary phase type and transition interface are effectively determined, thereby accurately revealing the evolutionary history of the above-water and underwater sedimentary environments of the continental delta and the location of the lakeshore, providing important and accurate geological information for the exploration of lithological oil and gas reservoirs.

[0099] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for identifying the shoreline of a continental delta, characterized in that: The steps include: Obtain the core and well logging curve of the selected well on the continental delta; determine the position of the sedimentary phase transition interface on the core based on the lithology of the core; calibrate the transition interface position of the well logging curve based on the transition interface position of the sedimentary phase on the core; A plurality of seismic profiles are obtained through three-dimensional seismic records including the selected well; the seismic profile passing through the selected well is calibrated according to the position of the sedimentary phase conversion interface in the well logging curve to obtain the position of the sedimentary phase conversion interface of the selected well in the seismic profile; Based on the position of the selected well sedimentary phase conversion interface on the seismic section, the isotropic axis of the selected well conversion interface on the seismic section is obtained, and the isotropic axis on the seismic section is traced laterally to obtain the shoreline point corresponding to the seismic section; Based on the position of the iso-axis on the seismic section, the iso-axis corresponding to the sedimentary phase transition interface in the remaining seismic sections is calibrated, and the remaining iso-axis is traced laterally to obtain the shoreline points corresponding to the remaining seismic sections; Based on the shoreline points corresponding to the seismic profile and the shoreline points corresponding to the remaining seismic profiles, the amplitude slices along the same axis are extracted to obtain the final distribution of the lake shoreline on the plane, thereby realizing accurate identification of the lake shoreline.

2. The method for identifying the shoreline of a continental delta according to claim 1, characterized in that: The method to correctly calibrate the conversion interface position of the logging curve is as follows: At the transition interface, if the natural potential curve of the sand body transitions from a funnel shape to a bell shape, the transition position between the funnel shape and the bell shape is the correct calibration position.

3. The method for identifying the lakeshore of a continental delta according to claim 1, characterized in that: The correct method for selecting the isotropic axis on the seismic section is as follows: On the seismic section, if the iso-axis on the seismic section has a lens-shaped reflection feature above and a progradational reflection feature below, the correct iso-axis is obtained.

4. The method for identifying the shoreline of a continental delta according to claim 1, characterized in that: During the lateral tracking process, the point where the amplitude of the same-direction axis is lower than the preset value is the shoreline point.

5. The method for identifying the shoreline of a continental delta according to claim 1, characterized in that: Lateral tracking uses automatic tracking methods or manual tracking methods.

6. The method for identifying the shoreline of a continental delta according to claim 1, characterized in that: The locations along the layer amplitude slice where the amplitude is lower than the preset value constitute the lake shoreline.

7. The method for identifying the shoreline of a continental delta according to claim 1, characterized in that: The iso-axis on the remaining seismic sections does not pass through the selected well, and the iso-axis on the remaining seismic sections is parallel to the iso-axis on the seismic section passing through the selected well.

8. The method for identifying the shoreline of a continental delta according to claim 1, characterized in that: The lithology above the conversion interface is gray-green mudstone, gray-black carbonaceous mudstone or thin-layer fine sandstone; the lithology below the conversion interface is gray-white thick-layer siltstone.

9. The method for identifying the shoreline of a continental delta according to claim 1, characterized in that: The number of selected wells is positively correlated with the accuracy of lakeshore restoration results.

10. A system for identifying the shoreline of a continental delta, characterized in that: include: A first position information acquisition module, which is used to acquire the core and well logging curve of a selected well in a continental delta; Determine the position of the sedimentary phase transition interface on the core based on the lithology of the core; calibrate the position of the transition interface of the logging curve based on the position of the sedimentary phase transition interface on the core; A second position information acquisition module, the second position information acquisition module is used to obtain a plurality of seismic profiles through three-dimensional seismic records containing the selected well; calibrate the seismic profile passing through the selected well according to the position of the sedimentary phase conversion interface in the well logging curve, and obtain the position of the sedimentary phase conversion interface of the selected well in the seismic profile; A seismic profile shoreline point acquisition module, which is used to acquire the isotropic axis of the selected well conversion interface on the seismic profile based on the position of the selected well sedimentary phase conversion interface on the seismic profile, and to laterally track the isotropic axis on the seismic profile to acquire the shoreline point corresponding to the seismic profile; A module for acquiring shoreline points of the remaining seismic profiles, the module for acquiring shoreline points of the remaining seismic profiles being used to calibrate the iso-axis corresponding to the sedimentary phase transition interface in the remaining seismic profiles based on the position of the iso-axis on the seismic profiles, and to perform transverse tracking on the remaining iso-axis to acquire shoreline points corresponding to the remaining seismic profiles; A shoreline point information processing module is used to extract the amplitude slices along the same axis based on the shoreline points corresponding to the seismic profile and the shoreline points corresponding to the remaining seismic profiles, obtain the final distribution of the lake shoreline on the plane, and realize accurate identification of the lake shoreline.

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