A seismic facies driven high-precision sedimentary microfacies recovery method for deep carbonate rocks
By employing a seismic-driven sedimentary microfacies reconstruction method, combined with 3D seismic and drilling logging data, the problem of insufficient accuracy in sedimentary facies reconstruction during deep carbonate rock exploration has been solved, enabling the creation of high-precision sedimentary microfacies maps.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2026-03-31
AI Technical Summary
Traditional sedimentary facies reconstruction methods suffer from insufficient accuracy, high subjectivity, and difficulty in accurately depicting sedimentary facies evolution in deep carbonate rock exploration, especially in areas with low drilling density.
A high-precision sedimentary microfacies reconstruction method driven by seismic facies was adopted. By combining three-dimensional seismic data, drilling and logging data and outcrop data, an isochronous sequence stratigraphic framework was established. High-precision isochronous sedimentary microfacies maps were drawn by utilizing seismic attribute optimization and sedimentary facies transformation relationships.
It enables accurate prediction of sedimentary facies zone boundaries even with limited drilling and outcrops, improving the accuracy of sedimentary feature reflection and increasing the agreement rate with actual drilling.
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Abstract
Description
Technical Field
[0001] This invention relates to sedimentary facies restoration methods, specifically a high-precision sedimentary microfacies restoration method for deep carbonate rocks driven by seismic facies, belonging to the field of petroleum exploration and development technology. Background Technology
[0002] Marine carbonate formations are an important area for oil and gas exploration in China, with high-quality reservoirs typically developing in dominant sedimentary facies zones such as shoals and reefs. During the exploration of carbonate formations in the Sichuan and Tarim Basins, a large number of large and medium-sized oil and gas fields have been discovered by using dominant sedimentary facies zones as a guide. As exploration progresses, higher precision is required in sedimentary facies reconstruction.
[0003] Traditional sedimentary facies reconstruction methods primarily rely on actual geological information obtained from outcrops and wells. They classify sedimentary facies using various facies markers and then construct planar sedimentary facies maps using a multi-factor comprehensive analysis and single-factor mapping method. While this method has significant limitations—offering only a partial view—it relies heavily on interpolation or expert experience for large areas between outcrops and wells, making it highly subjective and difficult to accurately delineate facies zone boundaries. Furthermore, traditional planar sedimentary facies mapping involves large time units, making it difficult to finely depict the evolution of sedimentary facies within a sequence. Simultaneously, as exploration progresses deeper into the basin, the well density in deep carbonate formations decreases significantly compared to shallower formations, making traditional sedimentary facies reconstruction methods unsuitable for areas with fewer wells. Summary of the Invention
[0004] This invention addresses the shortcomings of traditional techniques by providing a high-precision sedimentary microfacies restoration method for deep carbonate rocks driven by seismic facies, thus improving upon existing methods.
[0005] The technical solution adopted in this invention is: a method for high-precision sedimentary microfacies restoration of deep carbonate rocks driven by seismic facies, comprising the following steps:
[0006] S1. Basic Data Collection: Collect three-dimensional seismic bodies of the study area, drilling and logging data of the target layer, outcrop data, and relevant geological information.
[0007] S2. Well-seismic calibration: Conduct fine synthetic record calibration to establish the relationship between depth-domain drilling and logging geological information and time-domain seismic information.
[0008] S3. Establishing a regional isochronous sequence stratigraphic framework: Under the guidance of sequence stratigraphy theory, the third and fourth order sequences are divided, and a regional isochronous framework for the study area is established using a well-seismic combination approach. During this process, steps S2 and S3 must be repeatedly verified to achieve optimal matching, and then seismic horizon tracking is carried out.
[0009] S4. Well Logging Interpretation: Standardize the well logging data for the entire area to remove the influence caused by differences in equipment and year of acquisition, and then carry out well logging interpretation. Through core calibration, determine the grain threshold value, and then calculate the relevant thickness and stratigraphic sequence to calculate the grain-to-situ ratio (the ratio of grain beach thickness to stratigraphic thickness) as a quantitative sedimentary facies indicator.
[0010] S5. Sequence framework sedimentary facies classification: Based on core, thin section, and well logging interpretation, sedimentary facies are classified into third-order sequence and lower units according to various facies indicators.
[0011] S6. Seismic facies classification: Using the third-order sequence as the basic unit, waveform clustering seismic facies classification is carried out using three-dimensional seismic data. At the same time, facies surface analysis is carried out based on expert experience on typical cross-grid lines. After combining and verifying the two methods, typical seismic facies types are summarized.
[0012] S7. Establish seismic facies-sedimentary facies transformation relationship: Compare and analyze the sedimentary facies within the sequence framework divided by S5 and the seismic facies divided by S6 to establish typical seismic facies-sedimentary facies transformation relationship, and determine the sedimentary facies boundary within a single third-order sequence based on the sedimentary facies boundary.
[0013] S8. Delineation of stratigraphic slices within the isochronous sequence grid: Based on the principles of seismic sedimentology, isochronous stratigraphic slices are delineated within a single sequence unit using 3D seismic data. The specific number of stratigraphic slices should correspond to the number of well logging cycles that can be identified at level four or below.
[0014] S9. Optimization of Seismic Attributes: Seismic attributes are extracted from the three-dimensional seismic data volume. The correlation between seismic attributes and well logging is used to identify single-factor sedimentary indices. The plane sensitivity of seismic attributes is optimized to extract the attributes that best reflect the formation sedimentary characteristics.
[0015] S10. Establish the relationship between single-factor sedimentary indices and seismic attributes: Fit the selected seismic attributes with single-factor sedimentary indices to establish a fitting equation, so that seismic attributes can be converted into single-factor sedimentary indices.
[0016] S11. Perform isochronous stratigraphic slicing of attribute bodies: Based on S8, divide stratigraphic slices and create isochronous stratigraphic slices of seismic attribute bodies.
[0017] S12. High-precision isochronous sedimentary microfacies map drawing under seismic-sedimentary facies constraints: Based on the above content, under seismic-sedimentary facies constraints, the attribute volume stratigraphic slices made in S11 are transformed into planar single-factor sedimentary index slices according to the S10 fitting equation. Based on this, isochronous sedimentary microfacies maps are drawn and verified using reserved wells.
[0018] The technical effects of this invention are as follows:
[0019] This invention enables accurate prediction of sedimentary facies boundaries within a sequence stratigraphic unit by establishing sedimentary-seismic facies relationships, even in situations with limited drilling and outcrops. Further optimization utilizes seismic attributes that reflect sedimentary characteristics to calculate isochronous stratigraphic slices. Isochronous sedimentary facies maps are obtained through attribute-sedimentary correlation transformation. In practical applications, it has achieved excellent results with a high degree of agreement with actual drilling data. Attached Figure Description
[0020] Figure 1 This is a flowchart of the present invention;
[0021] Figure 2 A cross-sectional view of the tiered lattice structure as shown in the embodiment;
[0022] Figure 3 The statistical well logging particle-to-ground ratio distribution diagram is shown in the example.
[0023] Figure 4 The statistical logging particle-to-geographic ratio frequency distribution diagram is shown in the example.
[0024] Figure 5 This is a well-connected sedimentary facies diagram for an example.
[0025] Figure 6 The SQ1 seismic phase diagram is an example of this embodiment;
[0026] Figure 7 The SQ2 seismic phase diagram is an example of this embodiment;
[0027] Figure 8 The SQ3 seismic phase diagram is an example of this embodiment;
[0028] Figure 9 Seismic facies diagram of the Maokou Formation as an example;
[0029] Figure 10 The seismic facies-sedimentary facies transformation model is used as an example.
[0030] Figure 11 The preferred heatmap for seismic attributes in the embodiment;
[0031] Where: RMS is the root mean square amplitude, MA is the maximum amplitude, HE is the energy half-life, AE is the average energy, Q is the instantaneous Q factor, IP is the instantaneous phase, IF is the instantaneous frequency, t* is the t amplitude, and TI is the channel integral attribute;
[0032] Figure 12 This is a comparison chart of the plane sensitivity of seismic attributes in the embodiments;
[0033] Among them: a.Sweet; b.IF; c.RMS; d.TI; eQ; f.HE; g.AE; h.MA;
[0034] Figure 13Seismic attribute stratigraphic slice diagram for an example;
[0035] Wherein: a.SQ1_3; b.SQ1_6; c.SQ2_1; d.SQ2_4; e.SQ2_7; f.SQ3_3; g.SQ3_5; h.SQ3_8;
[0036] Figure 14 This is a high-precision isochronous depositional microphase diagram. Detailed Implementation
[0037] Combination Figure 1 The invention is further described by way of an example: a method for high-precision sedimentary microfacies reconstruction of deep carbonate rocks driven by seismic facies, comprising the following steps:
[0038] S1. Basic Data Collection: Collect three-dimensional seismic bodies of the study area, drilling and logging data of the target layer, outcrop data, and relevant geological information.
[0039] S2. Well-seismic calibration: Conduct fine synthetic record calibration to establish the relationship between depth-domain drilling and logging geological information and time-domain seismic information.
[0040] The seismic data in this case study area is a three-dimensional post-stack seismic body in region S. The wells in the area include JT-1, JG-1, YB-6, and YB-7. The strata studied are the Maokou Formation of the Permian.
[0041] S3. Establishing a regional isochronous sequence stratigraphic framework: Under the guidance of sequence stratigraphy theory, the third and fourth order sequences are divided, and a regional isochronous framework for the study area is established using a well-seismic combination approach. During this process, steps S2 and S3 must be repeatedly verified to achieve optimal matching, and then seismic horizon tracking is carried out.
[0042] The Maokou Formation in this case study area can be divided into three third-order sequences: SQ1, SQ2, and SQ3. Four sequence boundaries can be identified: SB1, SB2, SB3, and SB4. The three sequences are highly comparable across the S region (see [reference needed]). Figure 2 SQ1 exhibits a large thickness with little variation across different regions and a high GR value, indicating that the water body was generally deep during the deposition period of SQ1; SQ2 exhibits a relatively thin thickness with some variation in thickness across different regions and a low GR value; SQ3 exhibits a large variation in thickness across different regions, with a thickness that is thicker in the south and thinner in the north, and a corresponding GR value that is lower in the south and higher in the north.
[0043] S4. Well Logging Interpretation: Standardize the well logging data for the entire area to remove the influence caused by differences in equipment and year of acquisition, and then carry out well logging interpretation. Through core calibration, determine the grain threshold value, and then calculate the relevant thickness and stratigraphic sequence to calculate the grain-to-situ ratio (the ratio of grain beach thickness to stratigraphic thickness) as a quantitative sedimentary facies indicator.
[0044] In this example, the sequence grain-to-land ratio of the Maokou Formation was statistically analyzed in 18 wells in SQ3, 16 wells in SQ2, and 10 wells in SQ1. Figure 3 and Figure 4 ).
[0045] S5. Sequence framework sedimentary facies classification: Based on core, thin section, and well logging interpretation, sedimentary facies are classified into third-order sequence and lower units according to various facies indicators.
[0046] Among them, sedimentary facies classification and comparison Figure 5 The sedimentary facies of the Maokou Formation in this area during its depositional period consisted of carbonate platforms. Based on the different grain-to-situ ratios, the grain-to-situ ratios were correlated with the sedimentary microfacies. Combined with core sampling, a grain-to-situ ratio of 0.6 or higher corresponded to high-energy shoal microfacies, a grain-to-situ ratio between 0.3 and 0.6 corresponded to low-energy shoal microfacies, and a grain-to-situ ratio less than 0.3 corresponded to open sea / restricted sea microfacies.
[0047] S6. Seismic facies classification: Using the third-order sequence as the basic unit, waveform clustering seismic facies classification is carried out using three-dimensional seismic data. At the same time, facies surface analysis is carried out based on expert experience on typical cross-grid lines. After combining and verifying the two methods, typical seismic facies types are summarized.
[0048] The SQ1 seismic facies is divided into 4 categories, the SQ2 seismic facies into 6 categories, the SQ3 seismic facies into 6 categories, and the Maokou Formation as a whole into 5 categories. The plane boundaries of each seismic facies are clear. Figures 6 to 9 ).
[0049] S7. Establish seismic facies-sedimentary facies transformation relationship: Compare and analyze the sedimentary facies within the sequence framework divided by S5 and the seismic facies divided by S6 to establish typical seismic facies-sedimentary facies transformation relationship, and determine the sedimentary facies boundary within a single third-order sequence based on the sedimentary facies boundary.
[0050] Taking the overall seismic facies of the Maokou Formation as an example, this study combines typical well seismic profiles, waveform types and response characteristics, seismic facies characteristics, typical core and thin section characteristics, typical well logging facies and sedimentary structures, and single-factor sedimentary indices to classify seismic facies-sedimentary facies transformation models. Figure 10 ).
[0051] S8. Delineation of stratigraphic slices within the isochronous sequence grid: Based on the principles of seismic sedimentology, isochronous stratigraphic slices are delineated within a single sequence unit using 3D seismic data. The specific number of stratigraphic slices should correspond to the number of well logging cycles that can be identified at level four or below.
[0052] The stratigraphic slices were prepared separately for each of the three third-order sequences, resulting in good accuracy. The number of slices for each of the three third-order sequences varied depending on the research focus. For each third-order sequence, stratigraphic slices were interpolated based on the principle of even thickness distribution between each pair of tracing strata. Specifically, SQ1 corresponds to stratigraphic segment 7, with the bottom boundary slice of the Maokou Formation numbered SQ1_1, and subsequent slices numbered sequentially up to SQ1_7; SQ2 corresponds to stratigraphic segment 7, with the bottom boundary slice of SQ2 numbered SQ2_1, and subsequent slices numbered sequentially up to SQ2_7; SQ3 corresponds to stratigraphic segment 8, with the bottom boundary slice of SQ3 numbered SQ3_1, and subsequent slices numbered sequentially up to SQ3_8, and the top boundary slice of the Maokou Formation numbered SQ3_9. A total of 23 stratigraphic slices were prepared within the Maokou Formation.
[0053] S9. Optimization of Seismic Attributes: Seismic attributes are extracted from the three-dimensional seismic data volume. The correlation between seismic attributes and well logging is used to identify single-factor sedimentary indices. The plane sensitivity of seismic attributes is optimized to extract the attributes that best reflect the formation sedimentary characteristics.
[0054] The study extracted root mean square amplitude, maximum amplitude, energy half-decay time, average energy, instantaneous Q factor, instantaneous phase, instantaneous frequency, t-amplitude, and trace integral attributes according to a three-level sequence. In this example, six wells drilling through SQ3 within the 3D data range were analyzed, including YB-3, YB-6, YB-7, YS-1, YB-224, and JG-1. Correlation analysis was performed on the attribute values at well points and the particle-to-surface ratio above the wells, layer by layer, to obtain a correlation heatmap. Figure 11 ).
[0055] Among the parameters used to qualitatively evaluate sedimentary facies, instantaneous Q-factor, instantaneous frequency, and trace integral properties show good correlation and are theoretically more likely to reflect the true stratigraphic situation. Secondly, amplitude-related properties are the most sensitive and show relatively good correlation, exhibiting a better fit with the stratigraphy and providing support for sedimentary facies research.
[0056] To more clearly demonstrate the differences in planar response characteristics among different attributes of the same stratigraphic slice, the root mean square amplitude, maximum amplitude, energy half-life, average energy, instantaneous Q-factor, instantaneous frequency, t-amplitude, and trace integral attributes of slice SQ3_8 were extracted for study, and comparative maps were drawn. Seismic attribute beach response sensitivity analysis was conducted in conjunction with wellbore information. Figure 12 ).
[0057] Slice SQ_8 is located above SQ3, close to the top boundary of the Maokou Formation. Due to the exposure and erosion of the Maokou Formation at the end of its formation and the overlying Wujiaping Formation mudstone and shale strata, the top boundary of the Maokou Formation is a strong peak, which affects the adjacent area of the 3D seismic data and makes the amplitude attributes unclear in characterizing the platform margin boundary. Figure 12 a in Figure 12 c in the middle Figure 12 (g), but in the platform area, comparison with well-ground data provides a relatively good reflection of the grain shoal distribution. The energy half-life properties completely characterize the platform boundary in the late Maokou Formation SQ3 sequence. Figure 12 f), which is consistent with the boundary of the SQ3 seismic phase calculated using neural network waveform classification in S7 ( Figures 6 to 9 Instantaneous frequency and instantaneous Q-factor properties also characterize the terrace edge boundary to some extent. Figure 12 b, Figure 12 (e). The relative wave impedance of the channel integral not only provides a good characterization of the platform edge boundary, but also reflects the differences in the degree of development of granular shoals in the platform edge region. The red and yellow areas represent areas with developed granular shoals, while the green area represents the open sea area within the platform. Figure 12 (d) Its range is consistent with the range of the earthquake phase.
[0058] S10. Establish the relationship between single-factor sedimentary indices and seismic attributes: Fit the selected seismic attributes with single-factor sedimentary indices to establish a fitting equation, so that seismic attributes can be converted into single-factor sedimentary indices.
[0059] S11. Perform isochronous stratigraphic slicing of attribute bodies: Based on S8, divide stratigraphic slices and create isochronous stratigraphic slices of seismic attribute bodies.
[0060] A total of 23 stratigraphic slices were prepared according to the sequence framework. Representative stratigraphic examples were selected to illustrate the evolution of the Maokou Formation platform margin shoal. Specifically, the strata corresponding to SQ1 were SQ1_3 and SQ1_6 near the top and bottom; the strata corresponding to SQ2 were SQ2_1, SQ2_4, and SQ2_7 (lower, middle, and upper sections); and the strata corresponding to SQ3 were SQ3_3, SQ3_5, and SQ3_8 (lower, middle, and upper sections). Figure 13 As can be seen from the figure, in the early stage of SQ1 deposition, the red and yellow areas of the shoal response were relatively few and scattered, but increased significantly in the later stage, exhibiting a certain degree of banding. In the SQ2 deposition period, red and yellow low-resistivity areas were widely distributed, showing obvious banding, and were most concentrated in the southern part of the study area. Figures 6 to 9 It can be seen that the main seismic facies in this area during the SQ2 period were hillock-slope and medium-to-weak amplitude seismic facies. During the SQ3 period, the entire area showed a weak wave impedance response, with large areas of red and yellow appearing in the north. However, due to the rapid differentiation of the trough and platform during the SQ3 period, a large set of deep-water facies mudstone and shale deposits were deposited north of the platform edge. Their wave impedance was lower than that of the grainy limestone, which should be different from the shoal facies deposits of the indicator grainy limestone in the platform area.
[0061] S12. High-precision isochronous sedimentary microfacies map drawing under seismic-sedimentary facies constraints: Based on the above content, under seismic-sedimentary facies constraints, the attribute volume stratigraphic slices made in S11 are transformed into planar single-factor sedimentary index slices according to the S10 fitting equation. Based on this, isochronous sedimentary microfacies maps are drawn and verified using reserved wells.
[0062] Among them, eight typical isochronous stratigraphic slices were selected from the integral attributes and converted into isochronous sedimentary microfacies. Figure 14 During different periods of the Maokou Formation deposition, the distribution range of the platform margin shoals varied. In SQ1, they were scattered strips and dots, gradually transitioning to large-area contiguous distribution in SQ2 and SQ3, with good vertical continuity. Furthermore, in SQ3, they migrated northward in the Yuanba area, forming a pattern from north to south: slope-high-energy shoal-low-energy shoal-open sea.
[0063] The above description is merely an example of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of the claims.
Claims
1. A method for recovering high-precision sedimentary microfacies of deep carbonate rocks driven by seismic facies, characterized in that, Comprise the following steps: S1, basic data collection: collect the three-dimensional seismic body of the study area, the purpose layer drilling well logging, outcrop data, related geological profile data; S2, well-seismic calibration: carry out fine synthetic record calibration, establish the relationship between depth domain drilling well logging geological information and time domain seismic information; S3, establish regional isochronous sequence stratigraphic framework: under the guidance of sequence stratigraphy theory, divide three and four level sequences, and establish regional isochronous framework in the idea of well-seismic combination; S4, well logging interpretation: standardize the well logging data of the whole area, remove the influence caused by the difference of equipment and year of acquisition, then carry out well logging interpretation, determine the grain rock threshold value through core calibration, then calculate the grain ratio by layer sequence and thickness statistics, as quantitative sedimentary facies index; S5, sedimentary facies division in sequence framework: based on core, slice and well logging interpretation, carry out sedimentary facies division according to various facies marks in three level sequence and below as unit; S6, seismic facies division: take three level sequence as basic unit, use three-dimensional seismic to carry out waveform clustering seismic facies division, at the same time, carry out facies surface method analysis based on expert experience in typical well framework line, after mutual verification, summarize typical seismic facies type; S7, establish seismic facies-sedimentary facies conversion relationship: compare and analyze the sedimentary facies in sequence framework divided by S5 and the seismic facies divided by S6, establish typical seismic facies-sedimentary facies conversion relationship, determine the sedimentary facies boundary in single three level sequence according to the sedimentary facies boundary; S8, division of stratigraphic slice in isochronous sequence framework: based on seismic sedimentology principle, use three-dimensional seismic data to carry out isochronous stratigraphic slice division in single sequence unit; S9, optimization of seismic attribute: extract seismic attribute through three-dimensional seismic data body, optimize through the correlation between seismic attribute and single factor sedimentary index recognized by well logging on well and the planar sensitivity of seismic attribute, extract the attribute which can best reflect the sedimentary characteristics of stratum; S10, establish single factor sedimentary index-seismic attribute relationship: fit the optimized seismic attribute with single factor sedimentary index, establish fitting equation, so that the seismic attribute can be converted into single factor sedimentary index; S11, carry out attribute body isochronous stratigraphic slice: according to the division of stratigraphic slice in S8, carry out seismic attribute body isochronous stratigraphic slice making; S12, high precision isochronous sedimentary microfacies map drawing under the constraint of seismic facies-sedimentary facies.
2. The method according to claim 1, wherein, Before S4, it also includes constantly checking and repeating S2 and S3 steps to achieve optimal matching, and then carrying out seismic horizon tracking.
3. The method according to claim 1, wherein, In S8, the specific number of stratigraphic slices should correspond to the four level and below well logging identifiable cycle.
4. The method according to claim 1, wherein, The specific method of S12 is, according to the foregoing content under the constraint of seismic facies-sedimentary facies, convert the attribute body stratigraphic slice made in S11 into planar single factor sedimentary index slice according to the fitting equation in S10, draw isochronous sedimentary microfacies map accordingly, and use the reserved well for verification.