Quantitative fine evaluation method and system suitable for deepwater composite potential gas-bearing geologic body, storage medium and equipment

Abstract

The invention discloses a quantitative fine evaluation method suitable for a deepwater composite potential gas-bearing geologic body, and the method specifically comprises the following steps: extracting an instantaneous seismic amplitude attribute based on regional seismic data in a deepwater region, searching out the abnormal amplitude of a bright spot, and preliminarily focusing the range and horizon of the potential gas-bearing geologic body; determining a structure, a stratum and a lithologic boundary in the range and the horizon of the preliminarily focused potential gas-bearing geologic body, and determining a depicting range of the potential gas-bearing geologic body; establishing an AVO attribute quantity version, and fitting a gas containing rule; different types of AVO attribute carving bodies are obtained in the carving range of the potential gas-bearing geologic body; and in combination with drilling practice of drilled wells in a region, carrying out natural gas resource quantity measurement and calculation on III-type and II-type AVO attribute sculpture bodies, and estimating the gas bearing scale. According to the method, the limitation of single-type trap evaluation is avoided, the accuracy and reliability of potential gas-bearing geologic body description are improved, and the fine evaluation of the gas-bearing scale is supplemented.

Description

Technical Field

[0001] This invention relates to the field of natural gas exploration and development technology, and in particular to a quantitative and precise evaluation method, system, storage medium, and equipment suitable for deep-water complex potential gas-bearing geological bodies. Background Technology

[0002] As oil and gas exploration in nearshore deepwater areas deepens, the exploration of large-scale traps with a single type (structure, stratigraphy, or even lithology) has reached a bottleneck. Moving from simple to complex, the search for composite traps controlled by multiple factors has become an important direction for nearshore exploration. Nearshore deepwater areas, especially shelf slope breaks, possess the conditions for developing large-scale sand bodies such as submarine fans. However, due to later tectonic alteration, they often form complex geological bodies controlled by multiple factors including stratigraphy, lithology, and structure. These complex geological bodies often form favorable spatial superposition relationships with high-quality source rock strata that have reached mature to highly mature stages at depth. They are not only large-scale potential gas-bearing geological bodies but also important breakthroughs for discovering deepwater oil and gas reserves. However, the rationality of boundary delineation and the characterization of gas-bearing properties of complex potential gas-bearing geological bodies are challenges that need to be addressed due to the influence of multiple factors such as structure, stratigraphy, and lithology.

[0003] For characterizing the boundaries of potential gas-bearing geological bodies, besides conventional structural boundaries, lithological trap characterization techniques are predominantly used, with seismic attribute characterization of lithological trap extent being a relatively mature approach. For example, Chinese invention patent CN105372709B, based on well-seismic integration, establishes the correspondence between various lithological geological bodies on the drilling profile and seismic phases, identifying and interpreting lithological traps using seismic signals from sandstone. Chinese invention patent CN118131315A proposes using isochronous sequence stratigraphy and slicing techniques, with the predicted inversion body of reservoir sand bodies as the object, and adjacent slice horizons as analysis windows to perform profile tracking, identification, and planar characterization of lithological traps. Chinese invention patent CN114167515B considers the influence of fractures on lithological traps, thus refining the lithological trap extent to a certain extent. Chinese invention patent CN115877464B employs three-dimensional phase-controlled pseudo-well technology to train a deep learning model, improving the stability of lithological traps and finely characterizing them. Chinese invention patent CN111505720B identifies the type and distribution range of slope break zones, determining favorable sand body distributions to characterize lithological traps. Chinese invention patent CN116794722A, targeting areas with complex fault structures and rapid lateral changes in sand bodies, uses seismic attribute volume analysis to comprehensively determine the lithological and physical property boundaries of sand body reservoirs, thereby comprehensively identifying fault lithological traps.

[0004] Characterizing potential gas-bearing potential is exemplified by Chinese invention patent CN114428368B, which extracts hydrocarbon indicator (P*G) attributes based on pre-stack seismic gather data, fits the gas abundance values ​​of drilled wells with P*G attribute values, and determines gas-bearing boundaries. Chinese invention patent CN115480312B applies multi-interface AVO features to identify the hydrocarbon-bearing potential of complex fluvial facies lithological traps.

[0005] Existing technologies offer relatively mature methods for characterizing and delineating the boundaries of single-type traps and their gas-bearing boundaries, such as seismic geophysical inversion, seismic attribute analysis, and well-seismic cross-fitting, which are more suitable for continental oil and gas exploration. However, for nearshore deepwater exploration, where drilling costs are higher and drilling decisions are more cautious, the determination and precision of single-type boundaries alone cannot meet the exploration needs of complex potential gas-bearing geological bodies influenced by multiple factors including structure, stratigraphy, and lithology. Furthermore, deepwater marine potential gas-bearing geological bodies differ from continental geological bodies in terms of their unique characteristics, and currently lack quantitative standards and systematic methods suitable for precise characterization.

[0006] Therefore, there is an urgent need for a quantitative and precise evaluation method applicable to deep-water composite potential gas-bearing geological bodies. Summary of the Invention

[0007] This invention provides a quantitative and refined evaluation method suitable for deep-water complex potential gas-bearing geological bodies, improving the efficiency of comprehensive use of various data and information. It avoids the limitations of evaluating single-type traps, increases the accuracy and reliability of characterizing potential gas-bearing geological bodies, and supplements the refined evaluation of gas-bearing scale.

[0008] The first aspect of this invention provides a quantitative and precise evaluation method applicable to deep-water composite potential gas-bearing geological bodies, specifically including the following steps: Based on regional seismic data in deep water areas, instantaneous seismic amplitude attributes are extracted to search for "bright spot" amplitude anomalies, and the potential gas-bearing geological bodies and their stratigraphic positions are initially identified. Within the initially focused potential gas-bearing geological body range and stratigraphic level, the structural, stratigraphic, and lithological boundaries are defined to determine the delineation range of the potential gas-bearing geological body; Establish an AVO attribute scale and fit the gas content law; Different types of AVO property sculpted bodies were obtained within the delineation range of the potential gas-bearing geological body; Based on the drilling practices of existing wells in the region, natural gas resources are estimated for different types of AVO attribute sculpted bodies, and the gas-bearing scale is estimated.

[0009] The quantitative and refined evaluation method applicable to deep-water composite potential gas-bearing geological bodies, preferably, includes the following steps in the specific method of "determining tectonic boundaries": Seismic data were interpreted for the seismic reflection axes and their top and bottom edges corresponding to the identified "bright spot" amplitude anomalies, and structural maps of potential gas-bearing layers, as well as structural surfaces of the top and bottom plates, were drawn.

[0010] The quantitative and refined evaluation method applicable to deep-water composite potential gas-bearing geological bodies, preferably, includes the following steps in the specific method of "determining stratigraphic boundaries": Within the slope break range, the slope break range is determined by extracting the dip angle attribute and quantifying the range of dip angle changes. Within the slope bend range, find the line connecting the overburden or erosion points on the fan body to accurately identify the stratigraphic overburden or erosion boundary.

[0011] The quantitative and refined evaluation method applicable to deep-water composite potential gas-bearing geological bodies, preferably, includes the following steps in the specific method for "determining lithological boundaries": Sensitive elastic properties describing lithology are obtained through pre-stack seismic inversion. The distribution characteristics of well logging elastic properties under different lithological conditions are comprehensively studied. The probability density function of elastic properties for various lithologies is defined, and the probabilistic analysis of lithofacies is performed on each sample point of the inversion results. By applying Bayesian fuzzy discriminant mathematical analysis, the spatial distribution probability of various lithological types is calculated, thereby determining the lithological pinch-out boundary.

[0012] The quantitative and detailed evaluation method for deep-water composite potential gas-bearing geological bodies, preferably, includes the following steps in the step of "determining the characterization range of the potential gas-bearing geological body": The structural surfaces of the top and bottom plates are used to characterize the top and bottom extent of potential gas-bearing geological bodies; The planar characterization range of potential gas-bearing geological bodies is determined by using the lowest trap line range of the fault block where the tectonic high point is located, the stratigraphic overburden, the erosion boundary and the lithological pinch-out boundary as boundaries.

[0013] The quantitative and refined evaluation method applicable to deep-water composite potential gas-bearing geological bodies, preferably, includes the following steps in the step "establishing an AVO attribute scale and fitting gas-bearing patterns": Based on Gassmann fluid substitution theory, a series of forward AVO gathers are obtained through the Zoeppritz equation. The corresponding intercepts and gradients are obtained by inversion using the Shuey formula. These are then projected onto the intercept and gradient intersection plot to form the AVO interpretation scale. The intercept and gradient data obtained by inverting actual pre-stack seismic data using the Shuey formula are calibrated with the AVO interpretation scale. Porosity is then interpreted based on the AVO interpretation scale, and the porosity distribution law of the target area is finally obtained. The porosity law is used to characterize the gas-bearing law.

[0014] The quantitative and refined evaluation method applicable to deep-water composite potential gas-bearing geological bodies, preferably, includes the following steps in the step of "obtaining different types of AVO attribute sculpted bodies within the characterization range of the potential gas-bearing geological body": Within the top and bottom and planar characterization range of the potential gas-bearing geological bodies, attribute volume carving is performed using Type III and Type II AVOs, which represent different porosity patterns, to obtain the fine spatial distribution of the potential gas-bearing geological bodies within the characterization range.

[0015] A second aspect of the present invention provides a quantitative and fine characterization system suitable for deep-water complex potential gas-bearing geological bodies, comprising: The first processing unit extracts instantaneous seismic amplitude attributes based on regional seismic data in the deep water area, searches for "bright spot" amplitude anomalies, and initially focuses on the range and stratigraphic position of potential gas-bearing geological bodies. The second processing unit defines the structural, stratigraphic, and lithological boundaries within the initially focused potential gas-bearing geological body range and stratigraphic level, and determines the delineation range of the potential gas-bearing geological body. The third processing unit establishes an AVO attribute scale and fits the gas content pattern. The fourth processing unit acquires different types of AVO property sculpted bodies within the depiction range of the potential gas-bearing geological body; The fifth processing unit, in conjunction with the drilling practices of existing wells in the region, calculates the natural gas resource volume of different types of AVO attribute sculpted bodies and estimates the gas-bearing scale.

[0016] A third aspect of the present invention provides a computer storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the quantitative and fine evaluation method applicable to deep-water composite potential gas-bearing geological bodies.

[0017] A fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the quantitative and fine evaluation method applicable to deep-water composite potential gas-bearing geological bodies.

[0018] The beneficial effects are: This invention establishes a quantitative and precise evaluation method applicable to potential gas-bearing geological bodies with complex structures, stratigraphy, and lithology in nearshore deep waters. Through refined seismic data interpretation, quantitative slope breakage characterization, and Bayesian probabilistic lithofacies prediction using elastic parameters, the structural, stratigraphic, and lithological boundaries of potential gas-bearing geological bodies are quantitatively and precisely defined. Furthermore, by employing AVO attribute quantification porosity quantitative characterization technology, AVO attribute volumes with different porosity patterns are finely sculpted within the defined range, thereby providing a quantitative and accurate prediction of the gas-bearing scale of potential gas-bearing geological bodies. This offers better drilling guidance for nearshore deep-water exploration, where costs are higher and drilling decisions are more cautious.

[0019] This invention patent proposes a quantitative and refined evaluation process for deep-water composite potential gas-bearing geological bodies. The quantitative evaluation method of this process has higher scientific rigor and reliability, and improves the efficiency of comprehensive utilization of various data and information. It avoids the limitations of single-type trap evaluation, increases the accuracy and reliability of potential gas-bearing geological body characterization, and supplements the refined evaluation of gas-bearing scale.

[0020] The quantitative and detailed evaluation method of this invention has higher scientificity and reliability, improves the efficiency of comprehensive use of various data and information, avoids the limitations of single-type trap evaluation, increases the accuracy and reliability of potential gas-bearing geological body characterization, and supplements the detailed evaluation of gas-bearing scale. Attached Figure Description

[0021] Figure 1 This is an overall flowchart of the quantitative and refined evaluation method for deep-water composite potential gas-bearing geological bodies according to the present invention; Figure 2 This is a technical roadmap for the quantitative and refined evaluation method of deep-water composite potential gas-bearing geological bodies, applicable to the present invention. Figure 3 This is a seismic profile of the high-amplitude anomaly of the Sanya Formation sand body in the Y2 area of ​​southeastern Hainan in a specific embodiment of the present invention. Figure 4 Structural diagram of the SY3 sand body, a potential gas-bearing layer of the Sanya Formation, in the Y2 area of ​​the northern slope of the Songnan low uplift; Figure 5 A flattened profile of the slope gradient layer for the Y2 zone of the northern slope of the Songnan low convexity, calculated using inverse trigonometric functions; Figure 6 To provide a quantitative characterization of slope breakage and to accurately identify the overlap and erosion boundary map of the potential gas-bearing layer SY3 in the Y2 region; Figure 7-1 A schematic diagram showing the results of pre-stack seismic inversion to obtain sensitive elastic properties describing lithology; Figure 7-2 The results are from seismic facies analysis. Figure 7-3-1 This is a schematic diagram showing the distribution characteristics of elastic properties in well logging. Figure 7-3-2 To obtain the probability density function results of the elastic properties of various lithologies; Figure 7-4-1 For the determined lithofacies probability body results; Figure 7-4-2 The results show the determined planar distribution of lithofacies; Figure 8 Determine the lithological pinch-out profile for Bayesian probabilistic lithofacies prediction technology based on elastic parameters in region Y2; Figure 9-1 A flowchart illustrating the process of creating an AVO explanatory scale. Figure 9-2 This is a diagram illustrating the process of obtaining intercept and gradient data using the Shuey formula inversion. Figure 9-3 A schematic diagram illustrating the porosity interpretation of the AVO interpretation scale; Figure 10 This is a diagram showing the porosity distribution in region Y2. Figure 11 Spatial distribution diagram of AVO attribute volumes of type III and type II in region Y2. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] This invention provides a quantitative and refined evaluation method for deep-water composite potential gas-bearing geological bodies, specifically including the following steps: Based on regional seismic data in deep-water areas, instantaneous seismic amplitude attributes are extracted to search for "bright spot" amplitude anomalies, initially focusing on the range and stratigraphic level of potential gas-bearing geological bodies; within the initially focused range and stratigraphic level of potential gas-bearing geological bodies, structural, stratigraphic, and lithological boundaries are defined to determine the characterization range of the potential gas-bearing geological bodies; an AVO attribute quantification model is established and fitted with gas-bearing patterns; different types of AVO attribute sculptors are obtained within the characterization range of the potential gas-bearing geological bodies; combined with drilling practices of existing wells in the region, natural gas resource quantities are calculated for different types of AVO attribute sculptors to estimate the gas-bearing scale. This invention's quantitative and refined evaluation method has higher scientific rigor and reliability, improves the comprehensive utilization efficiency of various data and information, avoids the limitations of single-type trap evaluation, increases the accuracy and reliability of potential gas-bearing geological body characterization, and supplements the refined evaluation of gas-bearing scale. The following section uses a quantitative and precise evaluation method applicable to deep-water composite potential gas-bearing geological bodies as an example to illustrate the entire technical process in detail.

[0024] Example 1 like Figure 1 and Figure 2 The method shown is a quantitative and detailed evaluation method applicable to deep-water composite potential gas-bearing geological bodies, which specifically includes the following steps: S1: Based on regional seismic data in deep water areas, instantaneous seismic amplitude attributes are extracted to search for "bright spot" amplitude anomalies, and the potential gas-bearing geological bodies and their stratigraphic positions are initially identified.

[0025] Gas-bearing sandstones typically appear as "bright spots" amplitude anomalies on seismic profiles, especially in marine strata dominated by mud-encased sand. These "bright spot" amplitude anomalies can provide an initial indication of potential gas-bearing potential.

[0026] S2: In step S1, the potential gas-bearing geological body range and stratigraphic boundaries within the initially focused strata are defined to determine the delineation range of the potential gas-bearing geological body.

[0027] Nearshore deep-water areas, especially shelf slope breaks, have the potential to develop large-scale sand bodies such as submarine fans. However, due to subsequent tectonic alteration, they often form complex geological bodies controlled by multiple factors, including stratigraphy, lithology, and tectonics. Therefore, defining the extent of these geological bodies requires the combined influence of various boundary types, such as tectonic, stratigraphic, and lithological elements.

[0028] The specific method of step S2 includes the following steps: S21: Define the structural boundaries; S22: Determine stratigraphic boundaries; S23: Defining lithological boundaries; S24: Determine the characterization range of potential gas-bearing geological bodies; Specifically, step S21, "determining the construction boundary," includes the following steps: S211: Interpret seismic data for the seismic reflection axes and their top and bottom edges corresponding to the identified "bright spot" amplitude anomalies, and draw structural maps of potential gas-bearing layers, as well as structural surfaces of the top and bottom plates.

[0029] Specifically, step S22, "determining the stratigraphic boundary," includes the following steps: S221: Within the slope break range, the slope break range is determined by extracting the dip angle attribute and quantifying the dip angle variation range.

[0030] S222: Find the line connecting the overburden or erosion points on the fan body within the slope break range to accurately identify the stratigraphic overburden or erosion boundary.

[0031] Specifically, step S23, "determining lithological boundaries," includes the following steps: S231: Sensitive elastic properties describing lithology are obtained through pre-stack seismic inversion. The distribution characteristics of well logging elastic properties are comprehensively studied under different lithological conditions. The probability density function of elastic properties for various lithologies is defined, and probabilistic analysis of lithofacies is performed on each sample point of the inversion results.

[0032] S232: Apply Bayesian fuzzy discriminant mathematical analysis to calculate the spatial distribution probability of various lithological types, thereby determining the lithological pinch-out boundary.

[0033] Specifically, step S24, "determining the characterization range of potential gas-bearing geological bodies," includes the following steps: S241: Use the structural surfaces of the top and bottom plates obtained in step S211 as the top and bottom ranges of the potential gas-bearing geological body; S242: The planar characterization range of the potential gas-bearing geological body is determined by using the lowest trap line range of the fault block where the structural high point is located, the stratigraphic overburden obtained in step S222, the erosion boundary obtained in step S222, and the lithological pinch-out boundary obtained in step S232 as the boundary.

[0034] S3: Establish an AVO attribute scale and fit the gas content law.

[0035] AVO (Active Voorheological Detection) technology is an important tool for oil and gas identification. It is purely data-driven and highly applicable to oil and gas detection in near-shore deepwater exploration areas with few or no wells. Its principle is based on the assumption that rocks are composed of a framework and fluids, and it modifies parameters such as formation pore fluid saturation, pore fluid properties, and rock porosity.

[0036] The specific method includes the following steps: S31: Based on Gassmann fluid substitution theory, a series of forward AVO gathers are obtained through the Zoeppritz equation. The corresponding intercepts and gradients are obtained by inversion using the Shuey formula. These are then projected onto the intercept and gradient intersection plot to form the AVO interpretation scale.

[0037] S32: The intercept and gradient data obtained by inverting the actual pre-stack seismic data using the Shuey formula are calibrated with the AVO interpretation scale. Porosity is interpreted based on the AVO interpretation scale, and finally the porosity distribution law of the target area is obtained. The porosity law is used to characterize the gas-bearing law.

[0038] S4: Obtain different types of AVO attribute sculpted bodies within the depiction range of the potential gas-bearing geological bodies obtained in step S2.

[0039] Step S4 specifically includes the following steps: within the top and bottom and planar characterization range of the potential gas-bearing geological body in step S24, attribute volume carving is performed using Class III and Class II AVOs representing different porosity patterns to obtain the fine spatial distribution of the potential gas-bearing geological body within the characterization range.

[0040] S5: Based on the drilling practice of existing wells in the region, calculate the natural gas resource volume of the Class III and Class II AVO attribute sculptures obtained in step S4, and estimate the gas-bearing scale.

[0041] The present invention will now be described in detail with reference to a specific implementation method of the complex potential gas-bearing geological body in the Y2 area of ​​the northern slope of the Songnan low uplift in the deep water area of ​​the Qiongdongnan Basin.

[0042] The Songnan-Baodao Depression, located in the eastern part of the deep-water area of ​​the Qiongdongnan Basin, is a hydrocarbon-rich depression confirmed by drilling. During the Eocene to the Early Oligocene, the depression was in a relatively closed environment, which was favorable for the development of early lacustrine and shallow marine coal-bearing source rocks, indicating significant natural gas exploration potential. After the Miocene, the Songnan-Baodao Depression began to transition from a fault-bounded depression to a tectonic depression, forming a saucer-shaped structure with sedimentary thickness gradually decreasing from the center to the sides. The Y2 area on the northern slope of the Songnan Low Uplift on the southern edge of the depression possesses the conditions for the development of complex potential gas-bearing geological bodies.

[0043] S1: Based on regional seismic data in deep water areas, instantaneous seismic amplitude attributes are extracted to search for "bright spot" amplitude anomalies, and the potential gas-bearing geological bodies and their stratigraphic positions are initially identified.

[0044] Instantaneous seismic amplitude attributes were extracted from the 3D seismic data of the northern slope of the Songnan low uplift. A search for "bright spot" high-amplitude anomalies was conducted, revealing a significant "bright spot" amplitude anomaly at the bottom of the second member of the Sanya Formation in the Y2 area of ​​the northern slope of the uplift. Figure 3 The amplitude anomaly, as confirmed by drilling in the surrounding area, is a "bright spot" anomaly of the potential sand body in the SY3 layer. It is significantly modified by local faults and is a typical complex geological body with potential gas-bearing potential controlled by structure, strata and lithology.

[0045] S2: In step S1, the potential gas-bearing geological body range and stratigraphic boundaries within the initially focused strata are defined to determine the delineation range of the potential gas-bearing geological body.

[0046] S21: Define the structural boundary.

[0047] S211: The determination of tectonic boundaries is based on detailed interpretation of seismic data. Detailed interpretation of seismic data was performed on the SY3 layer corresponding to the identified "bright spot" amplitude anomaly, as well as three layers: the continuous mudstone within the second member of the Sanya Formation above it and the bottom of the Sanya Formation below it. A structural map of the potential gas-bearing SY3 layer was then drawn. Figure 4 ) as well as the top and bottom structural surfaces.

[0048] S22: Define stratigraphic boundaries.

[0049] S221: The stratigraphic boundary was determined based on the quantitative characterization technique of slope break. A slope break is a location where the angle changes abruptly. By extracting the dip angle attribute of the structural surface at the bottom of the Sanya Formation, the range of the slope break was quantitatively determined by the dip angle change range. The overlying strata were then flattened, and inverse trigonometric functions were used to calculate the vertical drop and horizontal distance. Figure 5 ), to clarify the slope gradient of the bottom interface of the Sanya Formation.

[0050] S222: Then, within the slope break range, find the line connecting the overburden or erosion points on the fan body. Based on the slope break characterization, finely identify the stratigraphic overburden and erosion boundaries within the slope break range. Figure 6 ).

[0051] S23: Define lithological boundaries.

[0052] S231: Lithological boundary delineation is based on Bayesian probabilistic lithofacies prediction technology using elastic parameters to determine lithological pinch-out lines. First, sensitive elastic properties describing lithology are obtained through pre-stack seismic inversion in the Y2 region. Under different lithological conditions, the distribution characteristics of these well-logging elastic properties are comprehensively studied. The probability density functions of the elastic properties for each type of lithology are defined, and probabilistic lithofacies analysis is performed on each sample point of the inversion results.

[0053] S232: Apply Bayesian fuzzy discriminant mathematical analysis to calculate the spatial distribution probability of various lithological types, thereby determining the pinch-out boundary of sand bodies. Figure 8 ).

[0054] Specifically: sensitive elastic properties describing lithology are obtained through pre-stack seismic inversion. Figure 7-1 Under different lithological conditions, the distribution characteristics of well logging elastic properties are comprehensively studied, and the probability density function of elastic properties for various lithologies is defined. Figure 7-3-1 , Figure 7-3-2 ), combined with seismic facies analysis results ( Figure 7-2 The Bayesian fuzzy discriminant mathematical analysis method is applied to calculate the spatial distribution probability of various lithological types. A probabilistic analysis of lithofacies is performed on each sample point in the inversion results to determine the lithological pinch-out boundary of the sand body. Figure 7-4-1 , Figure 7-4-2 ).

[0055] S24: Determine the characterization range of potential gas-bearing geological bodies.

[0056] S241: The top and bottom ranges of the potential gas-bearing geological bodies are defined by the continuous mudstone top plate of the second section of the Sanya Formation and the bottom of the Sanya Formation in step S211.

[0057] S242: The planar characterization range of the potential gas-bearing geological body is determined by using the lowest trap line range of the fault block where the structural high point of the SY3 layer is located, the stratigraphic overlay obtained in step S222, the erosion boundary obtained in step S222, and the lithological pinch-out boundary obtained in step S232 as the boundary.

[0058] S3: Establish an AVO attribute scale and fit the gas content law.

[0059] S31: As Figure 9-1 As shown, based on Gassmann fluid substitution theory, a series of forward AVO gathers are obtained through the Zoeppritz equation, and the corresponding intercepts and gradients are obtained by inversion using the Shuey formula. These are then projected onto the intercept and gradient intersection plot to form the AVO interpretation scale.

[0060] S32: Intercept and gradient data (e.g., obtained by inverting actual pre-stack seismic data using the Shuey formula) Figure 9-2 (As shown) and calibrated with the AVO interpretation scale, porosity interpretation is performed based on the AVO interpretation scale (e.g. Figure 9-3 As shown), the porosity distribution law of region Y2 was finally obtained ( Figure 10 The porosity regularity characterizes the gas-bearing regularity.

[0061] S4: Obtain different types of AVO attribute sculpted bodies within the depiction range of the potential gas-bearing geological bodies obtained in step S2.

[0062] In step S24, within the top and bottom and planar characterization range of the potential gas-bearing geological body, attribute volume carving is performed using Type III and Type II AVOs representing different porosity patterns to obtain the fine spatial distribution of the potential gas-bearing geological body within the characterization range. Figure 11 ).

[0063] S5: Based on the drilling practices of existing wells in the region, conduct a detailed evaluation of potential gas-bearing geological bodies and their gas-bearing scale.

[0064] Based on the natural gas accumulation pattern in Y2 area, the natural gas resource volume of different types of AVO attribute sculpted bodies obtained in step S4 is calculated, and the resource volume of the potential gas-bearing geological body SY3 in Y2 area is predicted to be 99.6 billion cubic meters.

[0065] Example 2 The above-described embodiment 1 provides a quantitative and detailed evaluation method suitable for deep-water composite potential gas-bearing geological bodies. Correspondingly, this embodiment provides a quantitative and detailed evaluation system suitable for deep-water composite potential gas-bearing geological bodies. The quantitative and detailed characterization system for deep-water composite potential gas-bearing geological bodies provided in this embodiment can implement the quantitative and detailed evaluation method for deep-water composite potential gas-bearing geological bodies of embodiment 1. This quantitative and detailed characterization system can be implemented through software, hardware, or a combination of both. For example, the quantitative and detailed characterization system can include integrated or separate functional modules or functional units to perform the corresponding steps in the methods of embodiment 1. Since the quantitative and detailed characterization system for deep-water composite potential gas-bearing geological bodies in this embodiment is basically similar to the method embodiment, the description process in this embodiment is relatively simple. Relevant details can be found in the description of embodiment 1. The quantitative and detailed characterization system for deep-water composite potential gas-bearing geological bodies in this embodiment is merely illustrative.

[0066] A quantitative and detailed characterization system suitable for deep-water complex potential gas-bearing geological bodies includes: The first processing unit extracts instantaneous seismic amplitude attributes based on regional seismic data in the deep water area, searches for "bright spot" amplitude anomalies, and initially focuses on the range and stratigraphic position of potential gas-bearing geological bodies. The second processing unit defines the structural, stratigraphic, and lithological boundaries within the initially focused potential gas-bearing geological body range and stratigraphic level, and determines the delineation range of the potential gas-bearing geological body. The third processing unit establishes an AVO attribute scale and fits the gas content pattern. The fourth processing unit acquires different types of AVO property sculpted bodies within the depiction range of the potential gas-bearing geological body; The fifth processing unit, in conjunction with the drilling practices of existing wells in the region, calculates the natural gas resource volume of different types of AVO attribute sculpted bodies and estimates the gas-bearing scale.

[0067] Example 3 The quantitative and detailed evaluation method for deep-water composite potential gas-bearing geological bodies described in Embodiment 1 can be specifically implemented as a computer program product. The computer program product may include a computer-readable storage medium on which computer-readable program instructions for executing the quantitative and detailed evaluation method described in Embodiment 1 are loaded.

[0068] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0069] Example 4 This embodiment provides a processing device for implementing the quantitative and detailed evaluation method for deep-water composite potential gas-bearing geological bodies provided in Embodiment 1. The processing device can be a client-side processing device, such as a mobile phone, laptop, tablet computer, desktop computer, etc., to execute the quantitative and detailed evaluation method of Embodiment 1.

[0070] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, memory, and communication interface are connected via the bus to enable communication between them. The memory stores a computer program that can run on the processor. When the processor runs the computer program, it executes the quantitative and refined evaluation method for deep-water composite potential gas-bearing geological bodies provided in Embodiment 1.

[0071] Preferably, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0072] Preferably, the processor can be any type of general-purpose processor such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation herein.

[0073] This invention establishes a quantitative and refined evaluation method applicable to potential gas-bearing geological bodies in nearshore deep-water areas, encompassing structural, stratigraphic, and lithological structures. Through refined seismic data interpretation, quantitative slope breakage characterization, and Bayesian probabilistic lithofacies prediction using elastic parameters, the structural, stratigraphic, and lithological boundaries of potential gas-bearing geological bodies are quantitatively and precisely defined. Finally, porosity interpretation is performed using AVO attribute quantification, and gas-bearing patterns are characterized by porosity regularities, enabling a refined evaluation of potential gas-bearing geological bodies. This addresses the lack of a systematic approach and insufficient precision in predicting the gas-bearing scale of potential gas-bearing geological bodies in deep-water areas where drilling costs are higher and drilling decisions are more cautious. A more scientific, reasonable, and objective systematic evaluation of potential gas-bearing geological bodies in the northern South China Sea deep-water area has been conducted, guiding the risk exploration process of potential gas-bearing geological bodies in deep-water areas such as the Y2 area on the southern margin of the Songnan Baodao Depression in the Qiongdongnan Basin and the B5 area on the northern slope of the Baiyun Depression in the Pearl River Estuary Basin, thus promoting research and exploration of potential gas-bearing geological bodies in deep-water areas.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quantitative and precise evaluation method applicable to deep-water composite potential gas-bearing geological bodies, characterized in that... Specifically, it includes the following steps: Based on regional seismic data in deep water areas, instantaneous seismic amplitude attributes are extracted to search for "bright spot" amplitude anomalies, and the potential gas-bearing geological bodies and their stratigraphic positions are initially identified. Within the initially focused potential gas-bearing geological body range and stratigraphic level, the structural, stratigraphic, and lithological boundaries are defined to determine the delineation range of the potential gas-bearing geological body; Establish an AVO attribute scale and fit the gas content law; Different types of AVO property sculpted bodies were obtained within the delineation range of the potential gas-bearing geological body; Based on the drilling practices of existing wells in the region, natural gas resources are estimated for different types of AVO attribute sculpted bodies, and the gas-bearing scale is estimated.

2. The quantitative and precise evaluation method for deep-water composite potential gas-bearing geological bodies according to claim 1, characterized in that, The specific method for "determining the structural boundary" includes the following steps: Seismic data were interpreted for the seismic reflection axes and their top and bottom edges corresponding to the identified "bright spot" amplitude anomalies, and structural maps of potential gas-bearing layers, as well as structural surfaces of the top and bottom plates, were drawn.

3. The quantitative and precise evaluation method for deep-water composite potential gas-bearing geological bodies according to claim 1, characterized in that, The specific method for "determining stratigraphic boundaries" includes the following steps: Within the slope break range, the slope break range is determined by extracting the dip angle attribute and quantifying the dip angle variation range. Within the slope bend range, find the line connecting the overburden or erosion points on the fan body to accurately identify the stratigraphic overburden or erosion boundary.

4. The quantitative and precise evaluation method for deep-water composite potential gas-bearing geological bodies according to claim 1, characterized in that, The specific method for "determining lithological boundaries" includes the following steps: Sensitive elastic properties describing lithology are obtained through pre-stack seismic inversion. The distribution characteristics of well logging elastic properties under different lithological conditions are comprehensively studied. The probability density function of elastic properties for various lithologies is defined, and the probabilistic analysis of lithofacies is performed on each sample point of the inversion results. By applying Bayesian fuzzy discriminant mathematical analysis, the spatial distribution probability of various lithological types is calculated, thereby determining the lithological pinch-out boundary.

5. The quantitative and precise evaluation method for deep-water composite potential gas-bearing geological bodies according to claim 1, characterized in that, The specific method for "determining the characterization range of potential gas-bearing geological bodies" includes the following steps: The structural surfaces of the top and bottom plates are used to characterize the top and bottom extent of potential gas-bearing geological bodies; The planar characterization range of potential gas-bearing geological bodies is determined by using the lowest trap line range of the fault block where the tectonic high point is located, the stratigraphic overburden, the erosion boundary and the lithological pinch-out boundary as boundaries.

6. The quantitative and refined evaluation method for deep-water composite potential gas-bearing geological bodies according to claim 5, characterized in that, The specific method for "establishing an AVO attribute scale and fitting gas content patterns" includes the following steps: Based on Gassmann fluid substitution theory, a series of forward AVO gathers are obtained through the Zoeppritz equation. The corresponding intercepts and gradients are obtained by inversion using the Shuey formula. These are then projected onto the intercept and gradient intersection plot to form the AVO interpretation scale. The intercept and gradient data obtained by inverting actual pre-stack seismic data using the Shuey formula are calibrated with the AVO interpretation scale. Porosity is then interpreted based on the AVO interpretation scale, and the porosity distribution law of the target area is finally obtained. The porosity law is used to characterize the gas-bearing law.

7. The quantitative and refined evaluation method for deep-water composite potential gas-bearing geological bodies according to claim 6, characterized in that, The specific method for "obtaining different types of AVO attribute sculpted bodies within the characterization range of the potential gas-bearing geological body" includes the following steps: Within the top and bottom and planar characterization range of the potential gas-bearing geological bodies, attribute volume carving is performed using Type III and Type II AVOs, which represent different porosity patterns, to obtain the fine spatial distribution of the potential gas-bearing geological bodies within the characterization range.

8. A quantitative and fine characterization system suitable for deep-water complex potential gas-bearing geological bodies, characterized in that, include: The first processing unit extracts instantaneous seismic amplitude attributes based on regional seismic data in the deep water area, searches for "bright spot" amplitude anomalies, and initially focuses on the range and stratigraphic position of potential gas-bearing geological bodies. The second processing unit defines the structural, stratigraphic, and lithological boundaries within the initially focused potential gas-bearing geological body range and stratigraphic level, and determines the characterization range of the potential gas-bearing geological body. The third processing unit establishes an AVO attribute scale and fits the gas content pattern. The fourth processing unit acquires different types of AVO property sculpted bodies within the depiction range of the potential gas-bearing geological body; The fifth processing unit, in conjunction with the drilling practices of existing wells in the region, calculates the natural gas resource volume of different types of AVO attribute sculpted bodies and estimates the gas-bearing scale.

9. A computer storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the quantitative and fine evaluation method for deep-water composite potential gas-bearing geological bodies as described in any one of claims 1 to 7.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the quantitative and fine evaluation method for deep-water composite potential gas-bearing geological bodies as described in any one of claims 1 to 7.

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