Shale sequence configuration determination system and method based on multi-source information fusion

Abstract

This invention discloses a multi-source information fusion-based shale sequence configuration determination system and identification method in the field of shale sequence configuration determination technology. The system includes a multi-source information fusion-based shale sequence boundary identification module; a multi-source information fusion-based shale sequence framework construction module; and a multi-source information fusion-based shale sequence configuration determination module. The system sequentially establishes a target layer outcrop profile database and a geochemical trace element profile database, and performs well-seismic combined identification of shale sequence boundaries. It then fuses standard outcrop profiles with single-well logging profiles, fuses single-well logging data with elemental data, and further fuses the standard outcrop profiles, elemental data, and single-well logging data to construct a shale sequence stratigraphic framework. Based on this framework, the external morphology of the shale sequence is described and characterized. This invention overcomes many shortcomings, such as the use of limited data, insufficient information fusion, and weak conceptual constraints related to sequence configuration.

Description

Technical Field

[0001] This invention belongs to the field of shale sequence configuration determination technology, specifically a shale sequence configuration determination system and identification method based on multi-source information fusion. Background Technology

[0002] The contradiction between oil and natural gas supply and demand in my country is becoming increasingly prominent. In 2020, my country's dependence on foreign oil reached 72.7% (and natural gas dependence reached 43%), far exceeding the 50% warning line, seriously restricting the development of the national economy and affecting national energy security. To further promote the sustainable development of my country's oil and gas industry, actively seeking new alternative energy sources is imperative. Academician Jia Chengzhao (2017) pointed out that onshore deep-sea formations, deep-sea oil and gas, and unconventional oil and gas are the three major alternative areas for my country's oil and gas resources. Among them, unconventional oil and gas includes tight sandstone oil and gas, shale oil and gas, etc.

[0003] The effectiveness of shale oil and gas exploration and development is influenced by many core factors, including the establishment of sequence stratigraphy and the identification of sequence configurations. For sandstone, in different locations within a basin, coarse sandstone, medium sandstone, fine sandstone, sandstone interbedded with mudstone, and sandstone interbedded with conglomerate overlap, forming different spatial combinations. These combinations are easily identifiable and have high distinguishability, making the establishment of sequence stratigraphy and the delineation of sequence configurations relatively simple. Shale or mudstone itself is a relatively homogeneous, monolithic formation, primarily consisting of very fine-grained clay and fine-grained silt, with limited distinguishability and unpredictable variations. When sedimentary basins are filled with shale and mudstone, it is difficult to clearly identify the internal sequence stratigraphy and sequence configurations. Without the ability to delineate the stratigraphy, subsequent work such as horizontal well development becomes difficult to deploy and implement.

[0004] "Sequence architecture" encompasses both the external morphology and internal structure of a sequence (Wu et al., 2015), reflecting a set of overall sequence morphological and internal infill information. Sequences develop within sedimentary basins, and their external morphology represents the structure naturally derived from the basin, primarily including rift-type and truncate-type. The rift-type can be further divided into single-fault (one side rifted, the other truncate) and double-fault (both sides rifted). The internal structure of sequence architecture mainly includes lithology and lithological assemblages. In coarse-grained sediments, this manifests as sandstone and its assemblages, conglomerate and its assemblages, etc., while in fine-grained mudstone and shale sediments, it is relatively ambiguous, appearing as "a relatively simple mudstone."

[0005] Sequence stratigraphy is crucial. Even in the early exploration stages, when sufficient geological, geophysical, and geochemical data are unavailable, the ability to quickly and efficiently determine the external morphology and internal structure of a sequence stratigraphy demonstrates its broad applicability. Furthermore, the importance of sequence stratigraphy is significant. For example, in the early exploration stages, identifying a single-fault sequence of coarse sandstone-mudstone allows engineers, even without other data, to roughly determine the location of favorable reservoirs and source rocks, and to further deploy wells for verification or direct development and utilization of oil and gas resources.

[0006] Currently, research on sequence stratigraphy of coarse-grained sedimentary rocks (including sandstone and conglomerate) is relatively weak and has not received widespread attention from the academic community. Research on shale sequence stratigraphy is almost nonexistent. Different experts, scholars, and geological engineers often make significant subjective judgments when dividing shale sequences in the same area and stratigraphic position, resulting in contradictory conclusions that severely restrict the research and utilization of shale oil and gas resources. The reasons for this lie in the limited availability of research data (in the early exploration stages, data was scarce, leading researchers to often use only one or two types of data), insufficient information integration, and weak constraints from the sequence stratigraphy concept (which does not conform to natural geological laws).

[0007] This invention overcomes many shortcomings such as limited data usage, insufficient information integration, and weak constraints from the concept of sequence stratigraphy, and is of great help in the construction of sequence stratigraphic frameworks for shale and the exploration and development of shale oil and gas resources. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide a shale sequence configuration determination system and identification method based on multi-source information fusion.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: a shale sequence configuration determination system based on multi-source information fusion, comprising...

[0010] A multi-source information fusion shale sequence interface identification module is used to identify different types of shale sequence interfaces;

[0011] A multi-source information fusion shale sequence stratigraphic framework construction module is used to establish a shale sequence stratigraphic framework;

[0012] A multi-source information fusion shale sequence configuration determination module is used to determine the shale sequence configuration.

[0013] The identification method for a shale sequence stratigraphy system based on multi-source information fusion includes the following steps:

[0014] Step 1: Through the shale sequence boundary identification module with multi-source information fusion, establish the target layer field outcrop profile database and geochemical trace element profile database in sequence, and perform well-seismic combined shale sequence boundary identification.

[0015] Step 2: Through the shale sequence stratigraphic framework construction module of multi-source information fusion, the information of the standard profile of the field outcrop and the logging profile of the single well are fused, the logging data of the single well is fused with the element data information, and then the information of the standard profile of the field outcrop, the element data and the logging data of the single well are fused to construct the shale sequence stratigraphic framework.

[0016] Step 3, the shale sequence configuration determination module based on multi-source information fusion, describes and characterizes the external morphology of the shale sequence based on the constructed shale sequence stratigraphic framework, and determines the shale sequence configuration.

[0017] Furthermore, based on field outcrop profile data, including lithology, paleontology, color, weathering degree, and vegetation cover.

[0018] Furthermore, based on the geochemical trace element profile database, including MgO / CaO, Rb / Sr, Sr / Cu, Rb / K, Sr / Ba, Ni / Co, U / Th, 1000*Zr / Al and 100*MgO / Al2O3.

[0019] Furthermore, when integrating standard field outcrop profiles with single-well logging profiles, a field outcrop profile closest to a single well is selected from the field outcrop profile database. Sequence interface information is read from this profile, and the thickness characteristics between sequence interfaces in the field outcrop profile are analyzed. The interface information and thickness characteristics are then extended to adjacent single wells for information fusion and calibration. Finally, the sequence of single wells is divided in conjunction with logging curves and logging lithology.

[0020] Furthermore, based on the sequence framework information reflected by the elemental data in the geochemical trace element profile database, single-well logging data and their variation characteristics are integrated to establish a single-well sequence framework.

[0021] The above-mentioned scheme has achieved the following beneficial effects: Currently, research on sequence stratigraphy of coarse-grained sedimentary rocks (including sandstone and conglomerate) is relatively weak and has not received widespread attention from the academic community; research on shale sequence stratigraphy is almost nonexistent. Different experts, scholars, and geological engineers often use highly subjective methods to delineate shale sequences within the same region and stratigraphic level, resulting in contradictory conclusions that severely restrict the research and utilization of shale oil and gas resources. The reasons for this lie in the limited availability of research data (in the early exploration stages, data was scarce, leading researchers to often use only one or two types of data), insufficient information integration, and weak constraints from the sequence stratigraphy concept (which does not conform to natural geological laws). This invention overcomes many shortcomings such as limited data use, insufficient information integration, and weak constraints from the sequence stratigraphy concept, and is of great help in the construction of shale and mudstone sequence stratigraphy frameworks and the exploration and development of shale and mudstone oil and gas resources. Attached Figure Description

[0022] Figure 1 This is an example diagram of shale sequence configuration in an embodiment of the present invention. Detailed Implementation

[0023] The features mentioned above in this application, or the features mentioned in the embodiments, can be combined arbitrarily. All features disclosed in this application specification can be used in any compositional form, and each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0024] The following detailed description illustrates the specific implementation method:

[0025] This application provides a shale sequence configuration determination system based on multi-source information fusion, including...

[0026] A multi-source information fusion shale sequence interface identification module is used to identify different types of shale sequence interfaces;

[0027] A multi-source information fusion shale sequence stratigraphic framework construction module is used to establish a shale sequence stratigraphic framework;

[0028] A multi-source information fusion shale sequence configuration determination module is used to determine the shale sequence configuration.

[0029] In this embodiment, a method for identifying shale sequence stratigraphy based on multi-source information fusion includes the following steps.

[0030] Step 1 involves using a shale sequence boundary identification module based on multi-source information fusion to identify different types of shale sequence boundaries. Specifically:

[0031] ① Establishment of a database of field outcrop profiles of the target layer

[0032] As mentioned earlier, shale and mudstone deposits often exhibit a degree of homogeneity, with limited differentiation in lithology and lithological assemblages. This makes it difficult to accurately identify shale and mudstone sequence boundaries on drilled profiles using well logging curves and lithological characteristics. However, sequence boundaries of shale and mudstone in outcrops are easily identifiable. By analyzing differences in ① lithology, ② paleontology, ③ color, ④ weathering degree, and ⑤ vegetation cover, sequence boundaries of shale and mudstone in outcrops can be readily identified. The lithology of outcrops in the field is similar to that revealed by drilling, primarily consisting of clay and silt, with low distinguishability. However, differences in paleontology, color, weathering degree, and vegetation cover are information that cannot be revealed by drilling. The fusion of this multi-source information allows for accurate identification of sequence boundaries in outcrops in the field.

[0033] ② Establishment of a database of geochemical trace element profiles of the target layer

[0034] Uniform sampling was conducted on both borehole cores and field outcrops, with particular attention paid to sampling in two areas where changes occurred in ① lithology, ② paleontology, ③ color, ④ weathering degree, and ⑤ vegetation cover. The MgO / CaO, Rb / Sr, Sr / Cu (reflecting paleoclimate), Rb / K, Sr / Ba (reflecting paleosalinity), Ni / Co, U / Th (reflecting redox conditions), 1000*Zr / Al, and 100*MgO / Al2O3 (reflecting paleowater depth) of the samples were analyzed. Sequence boundaries often correspond to the driest climate, highest salinity (lacustrine shale), lowest salinity (marine shale), strongest oxidation, and shallowest water depth.

[0035] Elemental logging (ECS) data was used to analyze the elemental variations of the entire subsurface strata. Combined with data on MgO / CaO, Rb / Sr, Sr / Cu, Rb / K, Sr / Ba, Ni / Co, U / Th, 1000*Zr / Al, and 100*MgO / Al2O3, the sequence boundary characteristics were revealed.

[0036] ③ Sequence boundary identification using well-seismic combined method

[0037] This content is a routine analysis. By analyzing the amplitude, frequency, and continuity of seismic reflection phase axes on seismic profiles, elements with different amplitudes, frequencies, and continuity are identified, and the elements are sequence boundaries.

[0038] By creating synthetic records to establish well-seismic correspondence, and combining the characteristics of natural gamma and sonic transit time logging curves, the position of the sequence interface in the drilling and seismic profiles was adjusted. After multiple adjustments, the sequence interface was accurately identified.

[0039] Step 2, the shale sequence stratigraphic framework construction module based on multi-source information fusion, is used to establish the shale sequence stratigraphic framework, specifically as follows:

[0040] ① Fusion of standard field outcrop profiles and single-well logging profiles

[0041] Based on the field outcrop profile database covering the entire area established in Module 1, single-well sequences are delineated. As mentioned earlier, it is difficult to accurately delineate shale sequences on single-well profiles using well logging curves and well logging lithology. Therefore, a field outcrop profile closest to a single well is selected from the field outcrop profile database, and the sequence interface information (content ① in Module 1) is read. The thickness characteristics between the sequence interfaces of the field outcrop profile are analyzed, and the interface information and thickness characteristics are extended to adjacent single wells for information fusion and calibration. The single-well sequences are then delineated by combining well logging curves and well logging lithology.

[0042] ② Fusion of single-well logging data and elemental data information

[0043] Single-well logging data can reflect sequence boundaries to a certain extent, and is used to delineate sequence frameworks. For example, a low natural gamma value represents a relative drop in sea (lake) level, which may be a sequence boundary. The strata sandwiched between two boundaries reflecting a relative drop in sea (lake) level constitute a sequence. Elemental information (single-well or field outcrop) can also reflect sequence boundaries (content ② in Module 1) and delineate sequence frameworks. Elemental indicators are more comprehensive, reflecting more information (including paleoclimate, paleodepth, paleosalinity, and redox environment), while logging curves can only reflect slight changes in lithology. Using the sequence framework information reflected by elemental data as a benchmark, single-well logging data and its variation characteristics are integrated to establish a single-well sequence framework.

[0044] ③ Integration of standard profiles of field outcrops, elemental data, and single-well logging data

[0045] For single wells without an adjacent field outcrop profile, a sequence stratigraphic framework is established based on content ② of Module 2. For single wells with an adjacent field outcrop profile, a sequence stratigraphic framework is established based on content ① and content ② of Module 2. When there is a mismatch between content ① and content ②, the five pieces of information revealed by the field outcrop profile, the four pieces of information revealed by the element data (nine indicators), and the one piece of information revealed by the well logging data are comprehensively analyzed, and the information is fused based on the "majority principle".

[0046] ④ Sequence stratigraphic framework construction

[0047] Based on the contents ①, ② and ③ in Module 2, sequence stratigraphy is divided on a single well to clarify the sequence stratigraphy scheme; sequence stratigraphy tracing and comparison are carried out on multi-well profiles, and a sequence stratigraphy framework is constructed in combination with seismic profile analysis (content ③ in Module 1).

[0048] Step 3, the shale sequence configuration determination module based on multi-source information fusion, is used to determine the shale sequence configuration. Specifically:

[0049] Based on content ④ in Module 2, and building upon the constructed sequence stratigraphic framework, the external morphology of shale sequences is described and characterized. Following reading conventions, the left-hand features of the sequence configuration are written first, followed by the right-hand features, connected by hyphens. Examples include fault-fault sequence, fault-bent sequence, bent-fault sequence, and depression sequence. Figure 1 ).

[0050] Through conventional techniques such as field outcrop profiling, core observation, well logging lithology interpretation, and seismic lithology inversion, the internal structural characteristics of sequence stratigraphy were clarified. Following the aforementioned reading conventions, information on sand-rich, calcium-rich, and mud-rich sequences is indicated in parentheses and sequentially appended to the corresponding external morphology, for example, fault (sand) – fault (mud) sequence stratigraphy, fault (sand) – fault (calcium) sequence stratigraphy, and depression (sand – calcium) sequence stratigraphy. (See attached...) Figure 1 As shown, in the appendix Figure 1 In the middle, (a) fault-fault sequence; (b) fault-bent sequence; (c) bend-fault sequence; (d) bend-depression sequence.

[0051] Currently, research on sequence stratigraphy of coarse-grained sedimentary rocks (including sandstone and conglomerate) is relatively weak and has not received widespread attention from the academic community; research on shale sequence stratigraphy is almost non-existent. Different experts, scholars, and geological engineers often exhibit significant subjectivity in dividing shale sequences within the same region and stratigraphic level, resulting in contradictory conclusions that severely restrict the research and utilization of shale oil and gas resources. The reasons for this lie in the limited availability of data sources (in the early exploration stages, data was scarce, leading researchers to often rely on only one or two types of data), insufficient information integration, and weak constraints from the sequence stratigraphy concept (which does not conform to natural geological laws).

[0052] This invention overcomes many shortcomings such as limited data usage, insufficient information integration, and weak constraints from the concept of sequence stratigraphy, and is of great help in the construction of sequence stratigraphic frameworks for shale and the exploration and development of shale oil and gas resources.

[0053] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A shale sequence stratigraphy determination system based on multi-source information fusion, characterized in that: include A multi-source information fusion shale sequence interface identification module is used to identify different types of shale sequence interfaces; A multi-source information fusion shale sequence stratigraphic framework construction module is used to establish a shale sequence stratigraphic framework; A multi-source information fusion shale sequence configuration determination module is used to determine shale sequence configuration; It also includes an identification method for a shale sequence stratigraphy system based on multi-source information fusion, comprising the following steps: Step 1: Through the shale sequence boundary identification module with multi-source information fusion, establish the target layer field outcrop profile database and geochemical trace element profile database in sequence, and perform well-seismic combined shale sequence boundary identification. Step 2: Using the shale sequence stratigraphic framework construction module with multi-source information fusion, the standard profile of the field outcrops is fused with the logging profile of a single well, the logging data of a single well is fused with the elemental data, and then the standard profile of the field outcrops, the elemental data, and the logging data of a single well are fused together to construct the shale sequence stratigraphic framework. When fusion of the standard profile of the field outcrops and the logging profile of a single well, the field outcrops closest to a single well are selected from the field outcrops profile database, the sequence interface information is read, the thickness characteristics between the sequence interfaces of the field outcrops are analyzed, and the interface information and thickness characteristics are extended to the adjacent single wells for information fusion and calibration. The sequence stratigraphic division of a single well is carried out in combination with logging curves and logging lithology. In step 3, the shale sequence configuration determination module, which integrates multi-source information, describes and characterizes the external morphology of the shale sequence based on the construction of the shale sequence stratigraphic framework, and determines the shale sequence configuration.

2. The identification method of the shale sequence stratigraphy system based on multi-source information fusion according to claim 1, characterized in that: Field outcrop profile data includes lithology, paleontology, color, weathering degree, and vegetation cover.

3. The identification method of the shale sequence stratigraphy system based on multi-source information fusion according to claim 2, characterized in that: The geochemical trace element profile database includes MgO / CaO, Rb / Sr, Sr / Cu, Rb / K, Sr / Ba, Ni / Co, U / Th, 1000*Zr / Al, and 100*MgO / Al2O3.

4. The identification method of the shale sequence stratigraphy system based on multi-source information fusion according to claim 3, characterized in that: Based on the sequence framework information reflected by the elemental data of the geochemical trace element profile database, single-well logging data and its variation characteristics are integrated to establish a single-well sequence framework.

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