A method and system for identifying lakeshore lines in continental deltas

Abstract

The present invention discloses a method and system for identifying the shoreline of a continental delta, which relates to the field of oil and gas geological exploration technology. By combining geology and geophysics, the system uses core observation results to calibrate well logging curves, and then calibrates three-dimensional seismic data, to comprehensively determine the development characteristics and accurate location of the shoreline in single wells, profiles, and planes. The system has greater applicability and practicality, providing a reliable basis for predicting the distribution of sand bodies in estuary bars and underwater diversion channels. By using core observations, well logging curve analysis, and analysis of three-dimensional seismic interpretation results, the system effectively determines the sedimentary facies type and its transition interface, thereby accurately revealing the evolutionary 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 lithologic oil and gas reservoir exploration, thereby resolving the problem of low identification accuracy in existing technologies.

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 increasing in-depth geological exploration of petroliferous basins, the direction of oil and gas exploration has shifted from structural reservoirs to lithologic reservoirs. The vicinity of the lakeshore is a favorable facies for the development of lithologic reservoirs. Due to the influence of longshore currents, the lakeshore plays a significant role in controlling the distribution of lithologic stratigraphic traps, primarily in the following four aspects: 1) The location and migration of the paleolakeshore control the distribution and vertical stacking pattern of sand bodies; 2) The paleolakeshore controls the formation and development of high-quality reservoirs; generally, underwater sand bodies have better reservoir properties than above-water sand bodies; 3) The frequent migration of the paleolakeshore provides favorable sedimentary conditions for the formation of reservoir-caprock assemblages; and 4) The vicinity of the paleolakeshore is a favorable zone for the development of lithologic reservoirs, with reservoirs exhibiting a skirt-like distribution along the paleolakeshore.

[0003] Core observation provides the most intuitive way to determine the sedimentary characteristics of strata, thereby analyzing the sedimentary environment of the study area during the depositional period. Observation and analysis of core samples directly reveal the characteristics and composition of subsurface rocks, including color, grain size, density, and mineralogy. This information can be used to determine geological features such as rock type and rock structure. Cores show evidence of bottom scour, climbing ripple bedding, parallel bedding, tabular cross-bedding, small trough cross-bedding, freshwater snail fossils, and charcoal fragments, all of which occur in continental deltaic environments. Core observation can also be used to validate seismic interpretations.

[0004] Well logs are obtained by measuring changes in the physical properties of subsurface rocks, such as resistivity, natural gamma radiation, and acoustic velocity. These changes can be correlated with different sedimentary facies, thereby identifying them. Typically, based on analysis of multiple data sources, including cores and well logs, the morphology and amplitude of well logs, such as spontaneous potential, natural gamma radiation, resistivity, and acoustic transit time, are used to characterize the log morphology corresponding to the sedimentation of underwater distributary channels and estuary bars at the delta front.

[0005] Synthetic recordings and attribute slicing are two commonly used processing and analysis methods in seismic exploration. These are generated by simulating phenomena such as reflection, refraction, and scattering during underground seismic wave propagation. They can be used to interpret stratigraphic reflection characteristics in actual seismic records. Three-dimensional seismic records can provide higher-resolution stratigraphic information, helping researchers understand changes in subsurface stratigraphic structure and sedimentary environments. Correcting the time and amplitude of actual seismic records has a significant effect on improving the accuracy of seismic interpretation and imaging. Slicing along amplitude can be compared and comprehensively analyzed with other seismic interpretations and geological data, providing more comprehensive geological interpretations 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 observations, 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] Researchers have investigated the restoration of ancient lakeshores. Application publication number CN112394400A, "A Quantitative Prediction Method, Apparatus, and System for Ancient Lakeshores," provides a method for predicting lakeshore distribution based on core observations. However, this method utilizes only core data, omitting seismic and well logging data, resulting in inaccurate restoration results. The paper "A Method for Identifying the Location of Ancient Lakeshores and Ancient Deep Lake Lines in Depressed Lake Basins," using the Chang 6 oil formation of the Late Triassic Yanchang Period in the Ordos Basin as an example, employs a variety of data, including core data, well logging, and field profiles, to systematically analyze and determine the formation mechanisms and identification characteristics of various typical landmarks near lakeshores and deep lake lines, including sedimentary structures, rock color, cycles, and fossils. However, the accuracy of ancient lakeshore prediction remains low. The article "A Rapid Determination Method for Delta Shorelines Using Multi-Well Silent Data" used core facies and sedimentary cycle analysis, combined with the identification of steep abrupt changes in thickness between marker layers, to determine the shoreline of the Chang 6 reservoir in the Ansai Oilfield, Ordos Basin. However, this method only analyzed sedimentary characteristics such as core data, sedimentary facies, and sedimentary cycles, and did not integrate 3D seismic data to analyze the location of the paleoshoreline. The article "Identification of Paleoshorelines and Their Control on Sandbodies and Oil and Gas" used multiple identification markers, including geomorphic features, unique lithologies, paleontological characteristics, sedimentary structures, geochemical indicators, and sedimentary facies transitions, to restore the shoreline, but this method lacked accuracy and operability. Summary of the Invention

[0007] The purpose of the present invention is to solve the problem of low accuracy and poor operability of the existing paleoshore identification method, and to provide a method and system for identifying the shoreline of a terrestrial delta.

[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 the shoreline of a continental delta, comprising the following steps:

[0010] Obtain the core and well logging curve of a selected well on a 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 sedimentary phase transition interface position 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 sedimentary phase transition interface of the selected well on the seismic section, the isotropic axis of the selected well transition interface on the seismic section is obtained, the isotropic axis on the seismic section is laterally traced, and the shoreline point corresponding to the seismic section is obtained;

[0013] Based on the position of the isotropic axis on the seismic section, the isotropic axis corresponding to the sedimentary phase transition interface in the remaining seismic sections is calibrated, and the remaining isotropic 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 upper side of the common-direction axis on the seismic section presents a lens-shaped reflection feature and the lower side presents a progradational reflection feature, the correct common-direction 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 transition interface is gray-green mudstone, gray-black carbonaceous mudstone or thin-layer fine sandstone; the lithology below the transition interface is gray-white thick-layer siltstone.

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

[0025] The present invention proposes a system for identifying lakeshore lines in continental deltas, comprising:

[0026] a first position information acquisition module, the first position information acquisition module being used to acquire a core and a well logging curve of a selected well in a continental delta; determine a position of a sedimentary phase transition interface on the core based on the lithology of the core; and calibrate a transition interface position of the well logging curve based on the position of the sedimentary phase transition interface on the core;

[0027] a second position information acquisition module, the second position information acquisition module being configured to obtain a plurality of seismic profiles from 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 transition interface in the well logging curve, and obtain the position of the sedimentary phase transition interface of the selected well in the seismic profile;

[0028] A seismic profile shoreline point acquisition module, which is used to obtain the isotropic axis of the selected well's sedimentary phase transition interface on the seismic profile based on the position of the selected well's sedimentary phase transition interface on the seismic profile, and to laterally track the isotropic axis on the seismic profile to obtain 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 laterally track the remaining iso-axis to acquire shoreline points corresponding to the remaining seismic profiles;

[0030] 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.

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

[0032] The proposed method for identifying lakeshores in continental deltas combines geology and geophysics, calibrating well logs with core observations and, in turn, seismic data, to comprehensively determine the developmental characteristics and precise location of lakeshores at the individual well, profile, and plan scales. This method offers enhanced applicability and practicality, providing a reliable basis for predicting the distribution of sand bodies in estuary bars and underwater distributary channels. By integrating core observations, well log analysis, and seismic interpretation, the method effectively identifies sedimentary facies types and transition interfaces, accurately revealing the evolutionary history of the above- and underwater sedimentary environments of continental deltas and the location of lakeshores. This provides crucial and accurate geological information for lithologic oil and gas reservoir exploration, addressing the low identification accuracy of existing technologies.

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

[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 selected, the richer the core data and logging data, and the more accurate the lakeshore restoration results.

[0035] The present invention proposes a continental delta lake shoreline identification system, which realizes 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, facilitating 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 following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

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

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

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

[0040] Figure 4 Schematic diagram of the seismic profile of the 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 the terrestrial delta lakeshore identification system diagram provided by the present invention.

[0043] Among them: 1-sedimentary phase transition interface on the core; 2-transition 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 section 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 section where the selected well is located; 15-remaining seismic sections. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only 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 herein 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 as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall 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, it does not need to be further defined or explained 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. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0048] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and 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 should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

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

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

[0052] S1. Obtaining a core and a well logging curve of a selected well in a continental delta; determining a position of a sedimentary facies transition interface on the core based on the lithology of the core; and calibrating a transition interface position of the well logging curve based on the position of the sedimentary facies transition interface 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 transition interface in the well logging curve, and obtaining the position of the sedimentary phase transition interface of the selected well in the seismic profile;

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

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

[0059] On the seismic section, if the upper side of the common-direction axis on the seismic section presents a lens-shaped reflection feature and the lower side presents a progradational reflection feature, the correct common-direction axis is obtained.

[0060] S4. calibrating 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 tracing 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] Horizontal 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, thereby realizing accurate identification of the lake shoreline.

[0065] The locations where the amplitude along the layer amplitude slice 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 sedimentary facies transition interface on the core based on the lithology of the core;

[0070] like Figure 2 and Figure 3 As shown, the 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 sedimentation environment to the underwater sedimentation environment.

[0072] The transition interface position of the core was determined based on the geological phenomenon that the lithology above the transition interface is gray-green mudstone, gray-black carbonaceous mudstone and thin fine sandstone; the lithology below the transition interface is gray-white thick 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 profile passing through the selected well according to the position of the sedimentary phase transition interface in the well logging curve to obtain the position of the sedimentary phase transition interface of the selected well on the seismic profile;

[0078] Based on the position of the sedimentary phase transition interface of the selected well on the seismic section, the isotropic axis of the selected well transition 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 coaxial axis is selected correctly:

[0080] On the seismic section, if the upper side of the common-direction axis shows a lens-shaped reflection feature and the lower side shows a progradational reflection feature, it means that the common-direction axis is correctly selected.

[0081] Step 6: Based on the position of the co-axial axis in step 5, the co-axial axes of the remaining seismic sections are calibrated; and the remaining co-axial axes are horizontally tracked to obtain the shoreline points corresponding to the remaining seismic sections;

[0082] During the horizontal tracking process 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 strength of the same-direction axis changes 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 same-direction axes of the remaining seismic sections do not pass through the selected well, and the same-direction axes of the remaining seismic sections are parallel to the same-direction axis in step 5.

[0086] Step 7: Extract the amplitude slices along the layer based on the symmetric axis calibrated in steps 5 and 6 to obtain the final lake shoreline, as shown in 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: the sedimentation period is an overcompensated shallow open-flow lake basin;

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

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

[0091] The cores are developed with bottom scour, climbing ripple bedding, parallel bedding, tabular cross-bedding, small trough cross-bedding, freshwater snail fossils and charcoal fragments.

[0092] The present invention proposes a system for identifying the shoreline of a continental delta lake. 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 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; and calibrate the transition interface position of the well logging curve based on the sedimentary phase transition interface position on the core;

[0094] The second position information acquisition module is used to obtain a plurality of seismic profiles through three-dimensional seismic records including 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 obtain 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 obtain 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 shoreline of a continental delta, which combines geology and geophysics, calibrates the well logging curve with the core observation results, and then calibrates the seismic data, and comprehensively determines the development characteristics and accurate position of the shoreline on a single well, profile and plane. It has stronger applicability and practicality, and provides a reliable basis for predicting the distribution of estuary dams and underwater diversion channel sand bodies. Compared with the existing technology, the present invention discloses a method for identifying the shoreline of a continental delta, which can accurately obtain the location of the shoreline 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 environment of the continental delta and the location of the shoreline, providing important and accurate geological information for the exploration of lithologic oil and gas reservoirs.

[0099] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection 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 a selected well on a 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 sedimentary phase transition interface position 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 sedimentary phase transition interface of the selected well on the seismic section, the isotropic axis of the selected well transition interface on the seismic section is obtained, the isotropic axis on the seismic section is laterally traced, and the shoreline point corresponding to the seismic section is obtained; Based on the position of the isotropic axis on the seismic section, the isotropic axis corresponding to the sedimentary phase transition interface in the remaining seismic sections is calibrated, and the remaining isotropic 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 direction axis are extracted to obtain the final distribution of the lake shoreline on the plane, thereby realizing accurate identification of the lake shoreline. Among them, the locations where the amplitude of the layer amplitude slice is lower than the preset value constitute 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 shoreline of a continental delta according to claim 1, characterized in that: The correct method for selecting the isotropic axis on a seismic section is as follows: On the seismic section, if the upper side of the common-direction axis on the seismic section presents a lens-shaped reflection feature and the lower side presents a progradational reflection feature, the correct common-direction 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: Horizontal 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 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.

7. 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.

8. 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.

9. A system for identifying the shoreline of a continental delta lake, characterized in that: include: A first position information acquisition module, the first position information acquisition module is used to obtain the core and logging curve of the selected well in 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 logging curve based on the sedimentary phase transition interface position on the core; a second position information acquisition module, the second position information acquisition module being configured to obtain a plurality of seismic profiles from 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 transition interface in the well logging curve, and obtain the position of the sedimentary phase transition interface of the selected well in the seismic profile; A seismic profile shoreline point acquisition module, which is used to obtain the isotropic axis of the selected well's sedimentary phase transition interface on the seismic profile based on the position of the selected well's sedimentary phase transition interface on the seismic profile, and to laterally track the isotropic axis on the seismic profile to obtain 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 laterally track 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; Among them, the locations where the amplitude of the layer amplitude slice is lower than the preset value constitute the lake shoreline.

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