Seismic facies driven deep carbonate rock high-precision sedimentary microfacies recovery method

Abstract

The invention discloses a seismic facies driven deep carbonate rock high-precision sedimentary microfacies recovery method. The method comprises the following steps: collecting basic data; well-seismic calibration is carried out; establishing a regional isochronous sequence stratigraphic framework; well logging interpretation; performing sedimentary facies division in the sequence framework; performing seismic facies division; establishing a seismic facies-sedimentary facies transformation relation; stratigraphic slices are divided in the isochronous sequence framework; preferably selecting seismic attributes; establishing a single-factor deposition index-seismic attribute relationship; carrying out attribute body isochronous stratigraphic slicing; and drawing a high-precision isochronous sedimentary microfacies diagram under seismic facies-sedimentary facies constraint. According to the method, the boundary of the sedimentary facies belt in the sequence can be accurately predicted by establishing the sedimentary-seismic facies relation under the conditions of well drilling and few outcrops; further optimizing seismic attributes capable of reflecting sedimentary characteristics, and calculating isochronous stratigraphic slices; and obtaining an isochronous sedimentary facies diagram through attribute-sedimentary correlation conversion. And a good effect is achieved in actual application, and the coincidence rate with an actual drilling well is high.

Description

Technical Field

[0001] The invention relates to a sedimentary phase restoration method, in particular to a high-precision sedimentary microphase restoration method for deep carbonate rocks driven by seismic phases, and belongs to the technical field of petroleum exploration and development. Background Art

[0002] Marine carbonate strata are an important direction for oil and gas exploration in China. High-quality reservoirs are usually developed in dominant sedimentary facies such as beaches and reefs. During the exploration of carbonate strata in Sichuan and Tarim Basin, a large number of large and medium-sized oil and gas fields were discovered under the guidance of dominant sedimentary facies. With the deepening of exploration, higher requirements are placed on the precision of sedimentary facies restoration.

[0003] The traditional sedimentary facies restoration method is mainly based on the actual geological information obtained from outcrops and drillings, and the sedimentary facies are divided by various phase markers, and then the planar sedimentary facies map is drawn according to the single factor mapping method based on the comprehensive analysis of multiple factors. Although this method has great limitations, it is a point-to-point glimpse of the whole. For the vast areas between outcrops and drillings, it mainly relies on interpolation or expert experience, which is highly subjective and difficult to accurately divide the boundaries of phase belts. Secondly, the time unit for drawing traditional planar sedimentary facies is large, and it is difficult to accurately depict the evolution of sedimentary facies within the sequence. At the same time, as exploration advances into the deep part of the basin, the density of wells encountered in deep carbonate formations in the same area is significantly lower than that of wells encountered in medium and shallow formations. The traditional sedimentary facies restoration method is difficult to use in areas with few wells. Summary of the invention

[0004] In view of the defects of traditional technical methods, the present invention provides a method for high-precision sedimentary microfacies recovery of deep carbonate rocks driven by seismic phases, and improves the problems existing in the existing technical methods.

[0005] The technical solution adopted by the present invention is: a method for recovering high-precision sedimentary microfacies of deep carbonate rocks driven by seismic phases, comprising the following steps:

[0006] S1. Basic data collection: Collect 3D seismic data in the study area, drilling and logging data of the target layer, outcrop data, relevant geological profiles and other data.

[0007] S2. Well-seismic calibration: Carry out fine synthetic record calibration to establish the relationship between drilling and logging geological information in the depth domain and seismic information in the time domain.

[0008] S3. Establish a regional isochronous sequence stratigraphic framework: Under the guidance of sequence stratigraphy theory, divide the third and fourth order sequences, and establish a regional isochronous framework for the study area based on the idea of ​​combining well and seismic data. During this process, steps S2 and S3 must be repeatedly checked to achieve the best match, and then seismic stratum tracking is carried out.

[0009] S4. Well logging interpretation: The well logging data of the whole area are standardized to remove the influence caused by the difference in the equipment and year of collection. Then the well logging interpretation is carried out. Through core calibration, the threshold value of grainstone is determined. Then the relevant thickness is counted and the grain-to-ground ratio (ratio of grain beach thickness to formation thickness) is calculated by sequence as a quantitative sedimentary facies indicator.

[0010] S5. Sedimentary facies division within the sequence framework: Based on core, thin section and well logging interpretation, sedimentary facies division is carried out according to various facies markers with the third-order sequence and below as units.

[0011] S6. Seismic facies division: With the three-level sequence as the basic unit, waveform clustering seismic facies division is carried out using 3D seismic. At the same time, facies analysis is carried out based on expert experience in typical well grid lines. After combining and verifying the two, typical seismic facies types are summarized.

[0012] S7. Establish the seismic phase-sedimentary phase transformation relationship: Compare and analyze the sedimentary phases within the sequence framework divided by S5 and the seismic phases divided by S6, establish a typical seismic phase-sedimentary phase transformation relationship, and determine the sedimentary phase boundaries within a single third-order sequence based on the sedimentary phase boundaries.

[0013] S8. Division of stratigraphic slices within the isochronous sequence framework: Based on the principles of seismic sedimentology, isochronous stratigraphic slices are divided within a single sequence unit using three-dimensional seismic data. The specific number of stratigraphic slices should correspond to the identifiable cycles of level 4 or below logging.

[0014] S9. Optimize seismic attributes: extract seismic attributes through three-dimensional seismic data volume, identify the correlation between single-factor sedimentary indicators through seismic attributes and well logging, optimize the plane sensitivity of seismic attributes, and extract the attributes that best reflect the sedimentary characteristics of the formation.

[0015] S10. Establishing the relationship between single-factor sedimentation index and seismic attribute: fitting the preferred seismic attribute with the single-factor sedimentation index, establishing a fitting equation, and enabling the seismic attribute to be converted into a single-factor sedimentation index.

[0016] S11, performing isochronous stratigraphic slicing of the attribute body: performing isochronous stratigraphic slicing of the seismic attribute body for the seismic attribute body according to the stratigraphic slice division in S8.

[0017] S12. Drawing of high-precision isochronous sedimentary microfacies maps under the constraints of seismic phase-sedimentary phase: Based on the above content and under the constraints of seismic phase-sedimentary phase, the stratigraphic slices produced in S11 are converted into planar single-factor sedimentary index slices according to the S10 fitting equation, and the isochronous sedimentary microfacies maps are drawn based on them, and tested with reserved wells.

[0018] The technical effects of the present invention are as follows:

[0019] The present invention can accurately predict the boundary of sedimentary phase belts in the sequence by establishing sedimentary-seismic phase relationship when there are few wells and outcrops; further optimize the seismic attributes that can reflect the sedimentary characteristics, calculate the isochronous stratigraphic slices; and obtain the isochronous sedimentary phase diagram through attribute-sedimentation correlation transformation. Good results have been achieved in practical application, with a high consistency rate with actual drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of the present invention;

[0021] Figure 2 A cross-sectional view of a sequence framework of an embodiment;

[0022] Figure 3 The distribution diagram of particle-to-ground ratio of statistical logging in the embodiment;

[0023] Figure 4 The frequency distribution diagram of the particle-to-ground ratio of the statistical logging of the embodiment;

[0024] Figure 5 A diagram of the well-connected sedimentary phase division of the embodiment;

[0025] Figure 6 The SQ1 seismic phase diagram of the embodiment;

[0026] Figure 7 The SQ2 seismic phase diagram of the embodiment;

[0027] Figure 8 The SQ3 seismic phase diagram of the embodiment;

[0028] Fig. 9 The seismic phase diagram of the Maokou Formation of the embodiment;

[0029] Fig.10 The seismic phase-sedimentary phase transformation model of the embodiment;

[0030] Fig.11 A preferred thermal map of seismic attributes of an embodiment;

[0031] Where: RMS is the root mean square amplitude, MA is the maximum amplitude, HE is the energy half-decay, 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 trace integration attribute;

[0032] Fig.12 A comparison diagram of the plane sensitivity of earthquake attributes of an embodiment;

[0033] Among them: a.Sweet; b.IF; c.RMS; d.TI; eQ; f.HE; g.AE; h.MA;

[0034] Fig.13A seismic attribute stratigraphic slice diagram of an embodiment;

[0035] Among them: 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] Fig.14 It is a high-precision isochronous deposition microphase map. DETAILED DESCRIPTION

[0037] Combination Figure 1 The present invention is further described by taking an example: a method for recovering high-precision sedimentary microfacies of deep carbonate rocks driven by seismic facies, comprising the following steps:

[0038] S1. Basic data collection: Collect 3D seismic data in the study area, drilling and logging data of the target layer, outcrop data, relevant geological profiles and other data.

[0039] S2. Well-seismic calibration: Carry out fine synthetic record calibration to establish the relationship between drilling and logging geological information in the depth domain and seismic information in the time domain.

[0040] Among them, the seismic data in the study area of ​​this example is a three-dimensional post-stack seismic body in the S area. The wells drilled in the area include JT-1 well, JG-1 well, YB-6 well, YB-7 well, etc. The study stratum is the Permian Maokou Formation stratum.

[0041] S3. Establish a regional isochronous sequence stratigraphic framework: Under the guidance of sequence stratigraphy theory, divide the third and fourth order sequences, and establish a regional isochronous framework for the study area based on the idea of ​​combining well and seismic data. During this process, steps S2 and S3 must be repeatedly checked to achieve the best match, and then seismic stratum 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 interfaces can be identified, namely SB1, SB2, SB3, and SB4. The three sequences are highly comparable in the S area (see Figure 2 ). SQ1 shows the characteristics of large thickness, small differences in different regions, and high GR value, indicating that the water body was generally deep during the SQ1 deposition period; SQ2 shows the characteristics of thin thickness, certain differences in thickness in different regions, and low GR; SQ3 shows the characteristics of large differences in thickness in different regions, thick in the south and thin in the north, and the GR value has the corresponding characteristics of low in the south and high in the north.

[0043] S4. Well logging interpretation: The well logging data of the whole area are standardized to remove the influence caused by the difference in the equipment and year of collection. Then the well logging interpretation is carried out. Through core calibration, the threshold value of grainstone is determined. Then the relevant thickness is counted and the grain-to-ground ratio (ratio of grain beach thickness to formation thickness) is calculated by sequence as a quantitative sedimentary facies indicator.

[0044] In this example, the single-layer sequence particle-to-ground ratio of Maokou Formation SQ3 is counted for 18 wells, SQ2 is counted for 16 wells, and SQ1 is counted for 10 wells ( Figure 3 and Figure 4 ).

[0045] S5. Sedimentary facies division within the sequence framework: Based on core, thin section and well logging interpretation, sedimentary facies division is carried out according to various facies markers with the third-order sequence and below as units.

[0046] Among them, the division and comparison of sedimentary phases are as follows: Figure 5 The sedimentary facies of the Maokou Formation in this area is carbonate platform. According to the different particle-to-ground ratios, the particle-to-ground ratios are matched with sedimentary microfacies. Combined with coring, the particle-to-ground ratios above 0.6 correspond to high-energy beach microfacies, the particle-to-ground ratios between 0.3 and 0.6 correspond to low-energy beach microfacies, and the particle-to-ground ratios less than 0.3 correspond to open sea\restricted sea microfacies.

[0047] S6. Seismic facies division: With the three-level sequence as the basic unit, waveform clustering seismic facies division is carried out using 3D seismic. At the same time, facies analysis is carried out based on expert experience in typical well grid lines. After combining and verifying the two, typical seismic facies types are summarized.

[0048] The SQ1 seismic phase is divided into 4 categories, the SQ2 seismic phase is divided into 6 categories, the SQ3 seismic phase is divided into 6 categories, and the Maokou Formation is divided into 5 categories. The plane boundaries of each seismic phase are clear ( Figures 6 to 9 ).

[0049] S7. Establish the seismic phase-sedimentary phase transformation relationship: Compare and analyze the sedimentary phases within the sequence framework divided by S5 and the seismic phases divided by S6, establish a typical seismic phase-sedimentary phase transformation relationship, and determine the sedimentary phase boundaries within a single third-order sequence based on the sedimentary phase boundaries.

[0050] Taking the overall seismic facies of the Maokou Formation as an example, the seismic facies-sedimentary facies transformation mode is divided into the following categories: Fig.10 ).

[0051] S8. Division of stratigraphic slices within the isochronous sequence framework: Based on the principles of seismic sedimentology, isochronous stratigraphic slices are divided within a single sequence unit using three-dimensional seismic data. The specific number of stratigraphic slices should correspond to the identifiable cycles of level 4 or below logging.

[0052] The stratigraphic slices are made in units of three-level sequences, with good accuracy. According to different research focuses, the number of slices in the three three-level sequences is also different. For each three-level sequence, the stratigraphic slices are interpolated according to the principle of tracing the layers in pairs and dividing them equally according to the thickness. Among them, SQ1 corresponds to 7 points of stratigraphy, and the bottom boundary slice of the Maokou Formation is numbered SQ1_1, and it is numbered to SQ1_7 in sequence; SQ2 corresponds to 7 points of stratigraphy, and the bottom boundary slice of SQ2 is numbered SQ2_1, and it is numbered to SQ2_7 in sequence; SQ3 corresponds to 8 points of stratigraphy, and the bottom boundary slice of SQ3 is numbered SQ3_1, and it is numbered to SQ3_8 in sequence, and the top boundary of the Maokou Formation is numbered SQ3_9; a total of 23 stratigraphic slices are made inside the Maokou Formation.

[0053] S9. Optimize seismic attributes: extract seismic attributes through three-dimensional seismic data volume, identify the correlation between single-factor sedimentary indicators through seismic attributes and well logging, optimize the plane sensitivity of seismic attributes, and extract the attributes that best reflect the sedimentary characteristics of the formation.

[0054] Among them, the 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 were extracted according to the three-level sequence for research. In this example, a total of 6 wells drilled through SQ3 within the three-dimensional data range, including YB-3, YB-6, YB-7, YS-1, YB-224, and JG-1, were extracted layer by layer. The attribute values ​​at the well points of different attributes and different slices were analyzed with the particle-to-ground ratio on the well to obtain the correlation heat map ( Fig.11 ).

[0055] Among them, under the condition that the particle-to-ground ratio is used as the qualitative evaluation parameter of sedimentary facies, the instantaneous Q factor, instantaneous frequency, and trace integral attributes have a good correlation with it, and theoretically can better reflect the real stratigraphic conditions. Secondly, the amplitude attribute is the most sensitive and has a relatively good correlation, and has a better fitting relationship with the stratigraphic formation, which can provide support for the study of sedimentary facies.

[0056] In order to more clearly show the differences in the plane response characteristics of different attributes of the same formation slice, the root mean square amplitude, maximum amplitude, energy half-decay, average energy, instantaneous Q factor, instantaneous frequency, t amplitude, and trace integral attributes of slice SQ3_8 were extracted for research, and comparative maps were drawn. Combined with the well information, the sensitivity analysis of the seismic attribute beach response was carried out ( Fig.12 ).

[0057] Slice SQ_8 is located in the upper part of SQ3, close to the top of the Maokou Formation. Due to the exposure and denudation of the Maokou Formation at the end and the overlying Wujiaping Formation mudstone strata, the top of the Maokou Formation is a strong wave peak, which affects the adjacent area of ​​3D seismic data, making the amplitude attributes unclear in describing the platform margin boundary ( Fig.12 a in Fig.12 Middle c, Fig.12 g), but the distribution of grain banks in the platform area is relatively well reflected by comparison with the well. The energy half-time attribute fully describes the platform margin boundary in the SQ3 sequence of the late deposition of the Maokou Formation ( Fig.12 f), which is consistent with the boundary of the SQ3 earthquake phase calculated by neural network waveform classification in S7 ( Figures 6 to 9 ). The instantaneous frequency and instantaneous Q factor properties also characterize the edge of the platform to a certain extent ( Fig.12 Middle b, Fig.12 e). The relative wave impedance of the channel integral attribute not only has a good description of the platform margin boundary, but also reflects the difference in the degree of grain beach development in the platform margin area. The red and yellow areas are the areas with grain beach development, and the green area is the open sea area within the platform ( Fig.12 d), its range is consistent with the earthquake phase range.

[0058] S10. Establishing the relationship between single-factor sedimentation index and seismic attribute: fitting the preferred seismic attribute with the single-factor sedimentation index, establishing a fitting equation, and enabling the seismic attribute to be converted into a single-factor sedimentation index.

[0059] S11, performing isochronous stratigraphic slicing of the attribute body: performing isochronous stratigraphic slicing of the seismic attribute body for the seismic attribute body according to the stratigraphic slice division in S8.

[0060] A total of 23 stratigraphic slices were made according to the sequence framework. Representative stratigraphic sections were selected to demonstrate the evolution of the platform margin beach of the Maokou Formation. The corresponding stratigraphic sections of SQ1 were selected from SQ1_3 and SQ1_6 near the top and bottom, the corresponding stratigraphic sections of SQ2 were selected from SQ2_1, SQ2_4, and SQ2_7 according to the lower, middle, and upper sections, and the corresponding stratigraphic sections of SQ3 were selected from SQ3_3, SQ3_5, and SQ3_8 according to the lower, middle, and upper sections. Fig.13 ), it can be seen from the figure that in the early stage of SQ1 deposition, the red and yellow areas of the beach body response were less and scattered, and in the late stage, they increased significantly and showed a certain stripe; in the SQ2 deposition period, the red and yellow low impedance areas were widely distributed, showing obvious stripe, which was most concentrated in the southern part of the study area. Figures 6 to 9 It can be seen that the main seismic phases in this area during the SQ2 period are hillock-shaped and medium-weak amplitude seismic phases; during the SQ3 period, the entire area showed a weak wave impedance response, and large red and yellow areas appeared in the north. However, due to the rapid differentiation of the trough and platform during the SQ3 period, a large set of deep-water shale deposits were deposited to the north of the platform edge. The wave impedance of these deep-water shale deposits was lower than that of the granular limestone, which should be distinguished from the beach phase deposits indicating granular limestone in the intra-platform area.

[0061] S12. Drawing of high-precision isochronous sedimentary microfacies maps under the constraints of seismic phase-sedimentary phase: Based on the above content and under the constraints of seismic phase-sedimentary phase, the stratigraphic slices produced in S11 are converted into planar single-factor sedimentary index slices according to the S10 fitting equation, and the isochronous sedimentary microfacies maps are drawn based on them, and tested with reserved wells.

[0062] The channel integral attributes are selected, and 8 typical isochronous stratigraphic slices are converted into isochronous sedimentary microfacies ( Fig.14 The distribution range of platform margin beaches varies in different periods of Maokou Formation deposition. SQ1 is a sporadic strip and dot distribution, which gradually transitions to a large-scale joint distribution in SQ2 and SQ3, with good vertical continuity. In SQ3, it migrates northward in the Yuanba area, forming a slope-high-energy beach-low-energy beach-open sea pattern from north to south.

[0063] The above description is only an example of the implementation of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A method for high-precision sedimentary microfacies recovery of deep carbonate rocks driven by seismic facies, characterized in that: The following steps are involved: S1. Basic data collection: Collect 3D seismic data, drilling and logging data of target layers, outcrop data, and related geological profile data in the study area; S2. Well-seismic calibration: Carry out fine synthetic record calibration to establish the relationship between drilling and logging geological information in the depth domain and seismic information in the time domain; S3. Establish regional isochronous sequence stratigraphic framework: Under the guidance of sequence stratigraphy theory, the third and fourth order sequences are divided, and the regional isochronous framework of the study area is established by combining well-seismic data; S4. Well logging interpretation: standardize the well logging data of the whole area to remove the influence caused by the difference in equipment and year of acquisition, and then carry out well logging interpretation. Through core calibration, determine the threshold value of grainstone, then count the relevant thickness and calculate the grain-to-ground ratio by sequence as a quantitative sedimentary facies indicator; S5. Sedimentary facies division within the sequence framework: Based on core, thin section and well logging interpretation, the sedimentary facies division is carried out according to the various facies marks with the third-order sequence and below as units; S6. Seismic facies division: Taking the third-level sequence as the basic unit, waveform clustering seismic facies division is carried out using 3D seismic. At the same time, phase surface analysis is carried out based on expert experience in typical well grid lines. After combining the two and verifying each other, typical seismic facies types are summarized. S7, establish the seismic phase-sedimentary phase transformation relationship: compare and analyze the sedimentary phases in the sequence framework divided by S5 and the seismic phases divided by S6, establish a typical seismic phase-sedimentary phase transformation relationship, and determine the sedimentary phase boundaries in a single third-order sequence according to the sedimentary phase boundaries; S8. Isochronous stratigraphic slice division within the sequence framework: Based on the principle of seismic sedimentology, isochronous stratigraphic slice division is carried out within a single sequence unit using 3D seismic data; S9. Optimize seismic attributes: extract seismic attributes through 3D seismic data volume, identify the correlation of single-factor sedimentary indicators through seismic attributes and well logging, optimize the plane sensitivity of seismic attributes, and extract the attributes that best reflect the sedimentary characteristics of the formation; S10, establishing a single-factor sedimentation index-seismic attribute relationship: fitting the preferred seismic attribute with the single-factor sedimentation index, establishing a fitting equation, so that the seismic attribute can be converted into a single-factor sedimentation index; S11, performing isochronous stratigraphic slicing of the attribute body: performing isochronous stratigraphic slicing of the seismic attribute body for the seismic attribute body according to the division of stratigraphic slices in S8; S12. Drawing of high-precision isochronous sedimentary microfacies maps under seismic phase-sedimentary phase constraints.

2. The method for recovering high-precision sedimentary microfacies of deep carbonate rocks driven by seismic facies according to claim 1, characterized in that: Before S4, it also includes continuous verification and repetition of S2 and S3 steps to achieve the best match, and then carry out seismic layer tracking.

3. The method for recovering high-precision sedimentary microfacies of deep carbonate rocks driven by seismic facies according to claim 1, characterized in that: In S8, the specific number of stratigraphic slices should correspond to the identifiable cycles of logging levels 4 and below.

4. The method for recovering high-precision sedimentary microfacies of deep carbonate rocks driven by seismic facies according to claim 1, characterized in that: The specific method of S12 is as follows: according to the above content, under the constraints of seismic phase-sedimentary phase, the stratigraphic slices of the attribute body produced in S11 are converted into planar single-factor sedimentary index slices according to the fitting equation of S10, and the isochronous sedimentary microfacies map is drawn based on it, and the reserved wells are used for verification.

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