A method for reproducing paleontological reef environment and predicting physical property distribution under geological thinking

Abstract

The application discloses a geological thinking-based palaeontological reef environment reproduction and physical property distribution prediction method, which comprises the following steps: firstly, performing optimization and interpretation on a seismic marker layer; secondly, performing horizon subdivision and seismic horizon interpretation on the biological reef; then, performing horizon flattening on seismic data with the seismic horizon H0 taking 0 ms or 0 m as a reference; then, performing mirror inversion transformation on the flattened seismic data; then, performing interpretation and sedimentary microfacies analysis on the mirror inversion transformed data; finally, comprehensively predicting the biological reef physical property based on multi-attribute fusion under the palaeogeomorphology. Through the above step-by-step application operation, the fine distribution of the sedimentary palaeogeomorphology in each period of the biological reef development process is effectively realized, and the prediction of the biological reef physical distribution is effectively realized by using the multi-attribute fusion of the comprehensive palaeogeomorphology and the seismic attribute, so that the fine prediction of the palaeogeomorphology and the development evolution and the physical property distribution of the biological reef is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil and gas reservoir exploration and development, and particularly relates to a method for reproducing a paleontological reef environment and predicting physical property distribution under geological thinking. BACKGROUND

[0002] The development of a biological reef has relatively high requirements for the environment, and the development of a biological reef requires suitable depth, clear seawater and sufficient sunlight; a complete biological reef experiences the processes of generation, development and extinction. The extinction of a biological reef is caused by deepening of water, shallowing of water-exposure and sufficient supply of clastic material, which causes turbidity of water, and the extinction of a biological reef is often accompanied by occurrence of a large tectonic event, such as rapid subsidence.

[0003] Due to the limitation of sparseness of drilled well points, the research on sedimentary microfacies is usually combined with well point constraint and seismic plane control, and the seismic layer flattening technology is one of indispensable key technologies. Compared with conventional sand-shale sedimentary microfacies, the research on the paleoenvironment of a biological reef sediment has its particularity, and the conventional seismic layer flattening technology cannot meet the requirements of fine research on the paleoenvironment of a biological reef sediment, and even leads people to the wrong direction. SUMMARY

[0004] The purpose of the application is to provide a new method for solving the deficiencies in the research on biological reef sedimentary microfacies and physical property distribution by using conventional overlying adjacent layer flattening, and to provide a method for realizing fine prediction of biological reef sedimentary microfacies and physical property distribution by fully utilizing tectonic restoration, layer flattening, data mirror transformation, data interpretation and multi-attribute fusion technology.

[0005] The technical purpose of the application is realized by the following technical scheme.

[0006] A method for reproducing a paleontological reef environment and predicting physical property distribution under geological thinking comprises the following steps.

[0007] Step 1: selection and interpretation of a seismic marker layer

[0008] In step 1: on the basis of regional tectonic development, a seismic event corresponding to a tectonic event causing extinction of a biological reef is determined on a seismic profile, which is located in the upper part of the biological reef in space, and fine seismic horizon H0 tracking is performed on the seismic event; generally, the seismic interface has relatively strong seismic amplitude, good continuity and stable phase, and is relatively easy to realize regional tracking and closure.

[0009] Step 2: horizon subdivision and seismic horizon interpretation of the biological reef

[0010] Since a complete bioherm undergoes a process of formation, development, and extinction, a more detailed understanding of its internal structure can reveal the differences in paleodepositional environments and the relative strength of bioherm development in different periods. This can be achieved through subdivision of small layers and tracing seismic horizons such as H1, H2, and H3.

[0011] Step 3: Flatten the seismic data by using seismic horizon H0 as a reference (0ms or 0m).

[0012] The data transformation formula for layer flattening is:

[0013] Y = Y0 - Y Ho ………………………………………(1)

[0014] Where: Yo is the time or depth value of a point in the data before the spatial flattening transformation, Y Ho Y0-Y represents the time or depth value of the Ho layer projected longitudinally from this point onto the Ho layer. Ho This indicates the interlayer thickness between the flattened layer and the reference layer Ho. Flattening of smaller layers and seismic bodies is then performed accordingly. A relatively larger value after flattening represents the reef core (with relatively large development thickness), and the target segment is located in the positive value zone.

[0015] Step 4: Perform mirror transformation on the flattened seismic data

[0016] After conventional flattening, the bioherms and seismic horizons H1, H2, and H3 in the seismic profile exhibit an upwardly concave morphology, with the concave distribution area indicating relatively well-developed and thick bioherms. This morphology is inconsistent with the actual morphology of the bioherms. By performing a mirror transformation using Formula 2, the distribution characteristics of paleogeography during the development of bioherms in each depositional period can be visually represented:

[0017] YY=(-1)*Y………………………………(2)

[0018] Where: Yo represents the time or depth value of a point in the data before the spatial mid-layer flattening transformation, and YY / represents the time or depth value of that point after the mirror transformation. After the transformation, the target segment (bioherm) is located in the negative value region. At this time, the morphology of the bioherm in the profile changes from concave to convex, intuitively reproducing the development morphology of the bioherm.

[0019] Step 5: Interpret the data after mirror transformation

[0020] After mirror transformation, the relative vertical relationships of the seismic stratigraphic layers are reversed compared to the original layers. At this point, the profile no longer has a temporal stratigraphic meaning; it represents an overlay of paleogeography of the bioherm during various depositional periods. The amplitude of each period represents the differences in paleogeographic elevation, and the temporal thickness or thickness between adjacent sublayers represents the relative development degree of the bioherm. From top to bottom, it indicates that the development of the bioherm gradually weakens until it disappears.

[0021] For negative longitudinal data after mirror transformation, the smaller the value at a given point, the higher the relative position of the paleoenvironmental landform, indicating more abundant sunlight and thus more favorable conditions for reef development. The development process of bioherms transitions from the highest stratigraphic indicator line to the zero baseline. Relative elevation indicates the planar distribution of paleosedimentary microfacies.

[0022] Step 6: Comprehensive prediction of bioherm properties based on multiple attributes under paleogeography

[0023] Bioherms are composed of limestone strata with high rock brittleness, and are generally prone to fracture development due to later tectonic influences. Therefore, the physical properties of bioherms are affected not only by the degree of porosity development but also by the degree of fracture development. By using paleogeomorphological data and fracture prediction results in a weighted fusion manner, combined with existing well drilling results, the planar distribution of bioherm physical properties can be predicted more effectively.

[0024] Through the above step-by-step application, the fine distribution of sedimentary paleogeography at various stages of bioherm development was effectively realized. By integrating multiple attributes of paleogeography and seismic properties, the distribution of bioherms was effectively predicted.

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] This invention discloses a method for reconstructing the environment and predicting the distribution of physical properties of paleontites based on geological thinking. Through the above step-by-step application of this method, the fine distribution of sedimentary paleogeography in each stage of the development of bioherms is effectively realized. By integrating multiple attributes of paleogeography and seismic properties, the distribution of bioherm material is effectively predicted. Attached Figure Description

[0027] Appendix Figure 1 Conventional seismic profiles and interpretation of seismic horizons;

[0028] Appendix Figure 2 The effect of flattening a regular layer;

[0029] Appendix Figure 3 Image showing the effect of flattening a regular layer and mirroring it;

[0030] Appendix Figure 4 Interpretation of data after mirror transformation;

[0031] Appendix Figure 5 Comparison of the prediction effects of the new method and the conventional method on paleogeographic morphology in period C (3D display);

[0032] Appendix Figure 6 Comparison of the prediction effects of the new method and the conventional method on paleogeomorphology in period C;

[0033] Appendix Figure 7 Comparison of the effectiveness of the new method with conventional methods in predicting reservoir properties;

[0034] attached Figure 8 F phase ~ A phase sedimentary environment evolution;

[0035] attached Figure 9 New method and conventional aspect biological reef sedimentary microfacies distribution prediction effect comparison;

[0036] attached Figure 10 Biological reef body C layer physical property distribution (3D display).

[0037] For those skilled in the art, without the premise of creative labor, other related figures can be obtained according to the above figures. DETAILED DESCRIPTION

[0038] The technical scheme of the present application will be further illustrated below in combination with specific examples.

[0039] Examples

[0040] The new technical method of the present application is used for studying the sedimentary microfacies and reservoir physical property distribution of the biological reef limestone reservoir of an oilfield in the South China Sea. The biological reef limestone of the oilfield is divided into A, B, C, D, E and F layers from top to bottom, and A, B, C, D, E and F are the top of the sublayer respectively. The burial depth of the target layer is about 2000m, the effective frequency band of the earthquake is 10-110HZ, the main frequency is about 55HZ, the average layer velocity of the target layer is about 3300m / s, and the seismic longitudinal resolution is about 7-11m.

[0041] 1. The specific process of predicting the biological reef sedimentary microfacies and physical property distribution

[0042] (1) Selecting the top of A layer as the seismic marker layer

[0043] From the structural development background and seismic profile of the area, the top of A layer is selected as the flattening layer for eliminating the structural influence under the guidance of the horizon calibration. From the top of A layer to the bottom of F layer, the seismic profile is flattened, and the seismic profile is shown in the following figure. Figure 1 As can be seen from the figure, the A layer has strong amplitude, high continuity and stable phase, and is distributed throughout the area. This set of limestone has similar sedimentary environment and is an ideal reference interface.

[0044] (2) Horizon subdivision and seismic horizon interpretation of the biological reef

[0045] The biological reef is divided into A, B, C, D, E and F layers from top to bottom. Based on the fine calibration of the synthetic seismogram and through the control of the continuous backbone profile, the fine seismic horizon interpretation is completed by using the methods of coherence volume, isochronous slice, waveform variable area profile, color profile, three-dimensional visualization and mutual verification, as shown in the following figure. Figure 1 .

[0046] (3) The seismic data and horizon are flattened with the seismic horizon A as the reference with 0 ms or 0 m

[0047] With the conventional horizon flattening method, the biological reef appears to be concave by time shifting the seismic horizons and seismic bodies upward by the time amount of A layer Figure 2 The effect can be seen that the biological reef appears to be concave after time shifting with the conventional method.

[0048] (4) The flattened seismic data are mirror transformed

[0049] The biological reef appears to be convex by mirror transforming the time shifted seismic data and horizon data, at this time, the biological reef shape in the seismic profile is consistent with the conventional shape, see the attached Figure 3 .

[0050] (5) The mirror transformed data are interpreted

[0051] The interpretation of the mirror transformed data can be divided into two parts: 1) the development history of the biological reef and the paleogeomorphology, from the attached figure 4, it can be seen that the planar difference of the study area paleogeomorphology gradually decreases from the E period to the A period, and the paleogeomorphology of the study area is nearly the same in the A sedimentary period; 2) the thickness of the sedimentary strata of each period, the thickness of each period is the thickness between the two horizons shown in the attached Figure 3 .

[0052] (6) Sedimentary microfacies and multi-attribute fusion biological reef property prediction under the comprehensive paleogeomorphology

[0053] The property of the biological reef is related to the paleogeomorphology, seismic amplitude, high and low frequency energy ratio, and frequency attenuation attribute, and the weighted fusion method is used to obtain the biological reef property body.

[0054] 2. Application effect and analysis

[0055] 1) Fine prediction of biological reef paleogeomorphology and sedimentary microfacies distribution

[0056] ① Biological reef paleogeomorphology

[0057] By comparing the biological reef paleogeomorphology obtained by the conventional stratum top flattening method with the recovery results of the biological reef paleogeomorphology under the new method (the attached Figure 5 ), it can be seen that: the biological reef shape under this method has the shape characteristics of modern typical biological reefs, the biological reef has a large height difference to the periphery, and has an ideal development environment for reef-building corals; at the same time, under the conventional method, the terrain difference in the region is small, which is not conducive to the survival of reef-building corals, etc.

[0058] ② Sedimentary microfacies distribution and sedimentary environment evolution

[0059] The paleogeomorphology controls the spatial distribution of the sedimentary microfacies, and the fine paleogeomorphology reconstruction technology and the results support the research of the sedimentary microfacies. Figure 6 ) and the sedimentary microfacies plane distribution (attached Figure 7 ) under the new method can be seen: under the new method, the distribution of the biological reef, the clastic beach and the lime mud mound facies in the C period is more concentrated and more regular.

[0060] From the comparison of the sedimentary paleogeomorphology from the F period to the A period (attached Figure 8 ), it can be seen that the new method intuitively reflects the process that the ancient biological reef gradually disappears from the F period to the A period, and reflects the development law of the formation, development and disappearance of the ancient biological reef.

[0061] 2) Fine understanding of the reservoir property distribution of the biological reef

[0062] The biological reef property distribution (attached Figure 9 ) is obtained by using the weighted fusion method in combination with the paleogeomorphology, the seismic amplitude, the high-low frequency energy ratio and the frequency attenuation attribute, and the effect comparison is shown in the attached Figure 10 It can be seen from the figure that the reservoir property distribution under the new method has the characteristics of the development of the biological reef.

[0063] In summary, the method successfully solves the limitations of the conventional layer flattening technology in the fine research of the biological reef sedimentary paleoenvironment, realizes the fine understanding of the biological reef sedimentary microfacies and the reservoir distribution by the reconstruction of the biological reef sedimentary paleogeomorphology and the multi-attribute reservoir prediction technology of the comprehensive paleogeomorphology, and the fine results are significantly improved.

[0064] The above has made an exemplary description of the present application, and it should be explained that, without departing from the core of the present application, any simple deformation, modification or other equivalent replacement which can not cost the creative labor of the person skilled in the art falls into the protection scope of the present application.

Claims

1. A method for reconstructing paleontological reef environments and predicting the distribution of physical properties based on geological thinking, characterized in that, Includes the following steps: Step 1: Selection and interpretation of seismic marker layers; The selection and interpretation of seismic marker layers are based on regional tectonic development. On the seismic profile, the seismic phase axis corresponding to the tectonic event that caused the bioherm extinction is determined. Spatially, it is located above the bioherm, and its seismic horizon H0 is tracked in detail. Step 2: Subdivide the bioherm into stratigraphic layers and interpret the seismic stratigraphic layers; The bioherm is divided into layers A, B, C, D, E, and F from top to bottom. Based on the fine calibration of synthetic seismic records and controlled by connecting the backbone profile, the interpretation of the seismic horizons is completed by cross-referencing methods such as coherence volume, isochronous slices, waveform variable area profiles, color profiles, and 3D visualization. Step 3: Flatten the seismic data by using seismic horizon H0 as a reference at 0ms or 0m; The data transformation formula for layer flattening is: Y=Y0-Y Ho Where: Y0 is the time or depth value of a point in the data before the spatial flattening transformation, Y Ho Project the point longitudinally onto H o H layer o The time or depth value of the layer, Y0-Y Ho Indicates the flattened layer and the reference layer H o The interlayer thickness is determined, and the sub-layers and seismic bodies are leveled accordingly. The relatively larger value after leveling represents the reef core, and the target segment is located in the positive value zone. Step 4: Perform a mirror transformation on the flattened seismic data; After performing a mirror transformation on the flattened seismic data, the bioherms and seismic horizons H1, H2, and H3 in the seismic profile exhibit an upwardly concave shape. The concave distribution area indicates relatively well-developed and thick bioherms. This shape is inconsistent with the actual shape of the bioherms. By performing a mirror transformation using Formula 2, the distribution characteristics of paleogeography during the development of bioherms in each depositional period can be visually presented. YY = (-1)*Y0 Where: Y0 is the time or depth value of a certain point in the data before the spatial mid-layer flattening transformation, and YY is the time or depth value of that point after the mirror transformation. After the transformation, the target segment of the bioherm is located in the negative value area. At this time, the shape of the bioherm in the profile changes from concave to convex, which intuitively reproduces the development morphology of the bioherm. Step 5: Interpret the data after mirror transformation; After mirror transformation, the relative relationship between the seismic layers and the original layers is reversed. At this time, the section no longer has a temporal stratigraphic meaning. It represents a superposition of paleogeography of bioherms in various depositional periods. The amplitude of each period represents the difference in paleogeographic elevation. The temporal thickness or thickness between adjacent small layers represents the relative development degree of bioherms. From top to bottom, it indicates that the development of bioherms gradually weakens and eventually disappears. The interpretation of data involves two aspects: (1) Paleomorphology For negative longitudinal data after mirror transformation, the smaller the value of a certain point, the higher the relative position of its paleoenvironmental landform, indicating that more sunlight is more conducive to reef development. The development process of bioherms is from the highest stratigraphic indicator line to the 0 baseline. The relative height indicates the planar distribution of paleosedimentary microfacies. The highest point of each layer is shifted to the 0 longitudinal baseline and then scaled down. The larger the value, the deeper the water body. The planar distribution of bioherm sedimentary microfacies is controlled by paleogeography. (2) Stratigraphic thickness The thickness of a certain stage of strata is the thickness sandwiched between the top surfaces of two smaller layers; Step 6: Integrate multiple attributes under paleogeography to predict bioherm properties.

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