Shallow-water delta sand body configuration method and system based on sequence stratigraphic sedimentary pattern

Abstract

The present application relates to a shallow-water delta sand body configuration method based on a sequence stratigraphic sedimentary pattern, and belongs to the technical field of geological analysis, comprising the following steps: establishing a shallow-water braided river delta plane sedimentary pattern of a study area; determining a three-level base level cycle sedimentary system domain; analyzing the scale and pattern of the sediment plane and profile according to the change of the base level, establishing a longitudinal and lateral sequence stratigraphic sedimentary pattern of the shallow-water delta; controlling the sand body resolution, realizing different precision sand body configuration identification and division; applying the sand body configuration combination relationship to carry out sand body classification research, and establishing a reservoir comprehensive classification chart. The present application also relates to a shallow-water delta sand body configuration system based on a sequence stratigraphic sedimentary pattern, and solves the problems of how to accurately and efficiently predict the spatial distribution form and scale of the sand body in the strong heterogeneous reservoir, and the diversification of the sand body configuration prediction results caused by personal subjective experience, guides the high-precision sand body configuration identification and division, and finally determines the longitudinal and lateral remaining oil distribution range.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geological analysis, and particularly relates to a shallow-water delta sand body configuration method and system based on sequence stratigraphic sedimentary patterns. BACKGROUND

[0002] Shallow-water braided river delta deposits are developed in large depression basins and faulted basins in China and are high-quality oil and gas reservoirs. The typical sedimentary characteristics of the shallow-water braided river delta deposits are thick continental deposits and alternating distribution of sandstone and mudstone, which results in strong vertical and horizontal heterogeneity of the reservoirs, and it is very difficult to finely describe the boundaries of the sand bodies and accurately predict the sand bodies between wells. It is always an important problem to accurately and efficiently predict the spatial distribution pattern and scale of the sand bodies in the strong heterogeneity reservoirs.

[0003] The key of the sand body configuration is to describe different levels of configuration interfaces and finally determine the vertical and horizontal remaining oil distribution range. The conventional sand body configuration methods include field outcrop, core observation, logging data analysis and the like. However, the same process is often used to carry out the sand body configuration level division for various sedimentary systems, the research efficiency is low, and the prediction results are diversified and different due to personal subjective experience.

[0004] In order to maximize the uniformity of the sand body configuration prediction results, it is very important to establish a clear standard mode to control the vertical and horizontal boundaries and superimposed relationship of the sand bodies for a certain type of sedimentary system in the reservoir fine characterization research. However, at present, there is a lack of a standard vertical and horizontal sedimentary mode based on sequence stratigraphy to guide the sand body configuration research for the shallow-water braided river delta sedimentary system.

[0005] The prior art has made a lot of research on the sand body configuration method, but there are two deficiencies: one is that the same process is often used to carry out the sand body configuration level division for different sedimentary systems, the research efficiency is low, and the prediction results are diversified and different due to personal subjective experience; and the other is that there is no idea of establishing a standard vertical and horizontal sedimentary mode based on the principle of sequence stratigraphy for the shallow-water braided river delta sedimentary system to apply a unified standard to guide the high-precision sand body configuration research. SUMMARY

[0006] In view of the above problems, the present application solves the problems of how to accurately and efficiently predict the spatial distribution pattern and scale of the sand bodies in the strong heterogeneity reservoirs and the diversification of the sand body configuration prediction results due to personal subjective experience, guides the high-precision sand body configuration identification and division, and finally determines the vertical and horizontal remaining oil distribution range.

[0007] In order to overcome the problems in the prior art, the present application provides the following technical scheme:

[0008] The shallow-water delta sand body configuration method based on sequence stratigraphic sedimentary patterns comprises the following steps:

[0009] According to the geological background, a shallow water braided river delta plane sedimentary model of the research area is established.

[0010] A three-level base level cycle sedimentary system domain is determined.

[0011] Under the constraint of the sedimentary system domain, according to the change of the base level, the scale and pattern of the sediment profile are analyzed, and a longitudinal and lateral sedimentary model of the shallow water delta sequence stratigraphy is established.

[0012] According to the longitudinal and lateral sedimentary model of the shallow water delta sequence stratigraphy, the sand body period and superimposed relationship of the target layer are predicted, the sand body resolution is controlled, and different precision sand body configuration identification and division are realized.

[0013] The sand body classification research is carried out by using the sand body configuration combination relationship, and a reservoir comprehensive classification chart is established.

[0014] Further, according to the geological background, the outcrop, core, drilling, microscopic observation data are collected and classified and analyzed, the paleostructure, paleoclimate and sedimentary environment of the research area are sorted out, and the shallow water braided river delta plane sedimentary model of the research area is predicted and established.

[0015] Further, the target layer sedimentary cycle is analyzed based on the theory of sequence stratigraphy, and the three-level base level cycle sedimentary system domain is determined by combining wells and seismic with the idea of point-line-surface.

[0016] Further, the three-level base level cycle sedimentary system domain determined by combining wells and seismic with the idea of point-line-surface includes: on the "point", the three-level base level cycle of the target layer is determined by combining the single well logging curve characteristics with the internal stratum of the sedimentary sequence; on the "line", the three-level sedimentary system domain is determined by combining the profile seismic facies characteristics with the lithofacies distribution range; on the "surface", the three-level base level cycle is verified again by combining the plane seismic reflection characteristics with the lithofacies distribution scale.

[0017] Further, under the constraint of the sedimentary system domain, according to the influence of the base level on the accommodated space, the scale and pattern of the sediment profile are analyzed, and the longitudinal sedimentary model of the shallow water delta sequence stratigraphy is established.

[0018] Further, under the constraint of the sedimentary system domain, according to the change of the base level, the scale and pattern of the sediment profile are analyzed, and the longitudinal and lateral sedimentary model of the shallow water delta sequence stratigraphy is established.

[0019] Further, the sand body resolution is controlled, and different precision sand body configuration identification and division are realized by using three methods, including: the application of logging curve characteristics to control the longitudinal resolution of the sand body, the seismic reflection characteristics to control the lateral resolution of the sand body, and the longitudinal and lateral wave velocity ratio inversion characteristics to control the distribution range of the sand body.

[0020] Further, according to the sand body configuration characteristics and single well productivity, the sand body is divided into three types in combination with the sand body rhythm, and a comprehensive classification chart of the reservoir is established.

[0021] Further, the sand body is divided into three types, including a uniform type, a uniform+composite type and a composite type.

[0022] The shallow-water delta sand body configuration system based on the sequence stratigraphic sedimentary pattern comprises a first determining unit, a second determining unit, a third pattern unit, a fourth identifying unit and a fifth classifying unit.

[0023] The first determining unit is used for establishing a shallow-water braided river delta plane sedimentary pattern of a research area according to a geological background.

[0024] The second determining unit is used for determining a three-level base level cycle sedimentary system domain.

[0025] The third pattern unit is used for establishing a shallow-water delta sequence stratigraphic longitudinal and lateral sedimentary pattern according to the variation of the base level to analyze the scale and style of the sediment plane and profile under the constraint of the sedimentary system domain.

[0026] The fourth identifying unit is used for predicting the sand body period and superimposed relationship of the target layer according to the shallow-water delta sequence stratigraphic longitudinal and lateral sedimentary pattern, controlling the sand body resolution, realizing the identification and division of different precision sand body configurations.

[0027] The fifth classifying unit is used for carrying out the sand body classification research by applying the sand body configuration combination relationship, and establishing a comprehensive classification chart of the reservoir.

[0028] The present application has the following beneficial effects: the present application is aimed at the strong heterogeneous reservoir of the shallow-water braided river delta sedimentary system, and comprehensively uses the macro and micro data such as field outcrop, core observation, microscopic analysis and seismic facies, establishes the longitudinal and lateral sedimentary standard pattern of the reservoir based on the principle of sequence stratigraphy to control the longitudinal and lateral boundaries of the sand body, thereby guiding the high-precision sand body configuration identification and division; the longitudinal and lateral sedimentary standard pattern of the reservoir is established based on the principle of sequence stratigraphy to control the longitudinal and lateral boundaries of the sand body, thereby guiding the high-precision sand body configuration identification and division, and finally determining the longitudinal and lateral remaining oil distribution range, which has important application significance for the fine description of the reservoir in the development stage.

[0029] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the description and the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and the other drawings can be obtained by those skilled in the art without creative effort based on these drawings.

[0031] Figure 1 A configuration method flowchart of the present application is shown;

[0032] Figure 2 A shallow-water braided river delta sedimentary model schematic diagram of the embodiment of the present application is shown;

[0033] Figure 3 A shallow-water braided river delta sequence stratigraphy longitudinal sedimentary model schematic diagram of the embodiment of the present application is shown;

[0034] Figure 4 A shallow-water braided river delta sequence stratigraphy horizontal sedimentary model schematic diagram of the embodiment of the present application is shown;

[0035] Figure 5 A shallow-water braided river delta sand body classification chart schematic diagram of the embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0037] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first", "second", and the like in the present application are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so as to describe the embodiments of the present application described herein. In the present application, the terms "up", "down", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings.

[0039] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0040] As Figure 1 According to the implementation flowchart, the present application proposes a shallow-water delta sand body configuration method based on layer sequence sedimentary pattern, and the flow is as follows:

[0041] According to the geological background, outcrop, drilling, core and other data are collected, the geological background of the research area is combed, and the shallow-water braided river delta plane sedimentary pattern of the research area is established;

[0042] Hierarchical control: according to the characteristics of single well logging curve, the characteristics of profile seismic reflection, and the characteristics of plane river channel scale, the sedimentary system domain of three-level base level cycle is determined;

[0043] Sequence constraint: under the constraint of the sedimentary system domain, the scale and style of the sediment plane and profile are analyzed according to the change of the base level, the influence of the base level change on the accommodated space, and the longitudinal and lateral sedimentary pattern of the shallow-water delta layer sequence is established;

[0044] Well-to-seismic combination: according to the longitudinal and lateral sedimentary pattern of the shallow-water delta layer sequence, the sand body period and superimposed relationship of the target layer are predicted, the sand body resolution is controlled, and different precision sand body configuration identification and division are realized;

[0045] Dynamic verification: the sand body classification research is carried out by applying the sand body configuration combination relationship, the reservoir comprehensive classification chart is established, and the standard for accurately identifying the relatively high permeability area of the development unit is provided.

[0046] A shallow-water delta sand body configuration system based on layer sequence sedimentary pattern is also provided, comprising: a first determining unit, a second determining unit, a third pattern unit, a fourth identifying unit and a fifth classifying unit;

[0047] The first determining unit is used to establish the shallow-water braided river delta plane sedimentary pattern of the research area according to the geological background;

[0048] The second determining unit is used to determine the sedimentary system domain of three-level base level cycle;

[0049] The third pattern unit is used to establish the longitudinal and lateral sedimentary pattern of the shallow-water delta layer sequence under the constraint of the sedimentary system domain according to the change of the base level;

[0050] The fourth identifying unit is used to predict the sand body period and superimposed relationship of the target layer according to the longitudinal and lateral sedimentary pattern of the shallow-water delta layer sequence, control the sand body resolution, and realize different precision sand body configuration identification and division;

[0051] The fifth classification unit is used for carrying out sand body classification research by applying sand body configuration combination relationship, and establishing a reservoir comprehensive classification chart.

[0052] In the embodiment, the invention is further described in detail by taking the study on the Jurassic Shaximiao Formation sand body configuration in the gently inclined and depressed Jurassic Shaximiao Formation in the central Sichuan Basin as an example.

[0053] S101, the outcrop, drilling and core data are comprehensively used to comb the geological background of the research area, and the shallow water braided river delta plane sedimentary model is determined;

[0054] S102, based on the theory of sequence stratigraphy, the sedimentary system domain of the three-level base level cycle is determined by combining the well and seismic data in the idea of point-line-plane;

[0055] S103, under the constraint of the sedimentary system domain, the scale and style of the sediment plane and profile are analyzed according to the change of the base level, and the longitudinal and lateral sedimentary model of the shallow water delta sequence stratigraphy is established;

[0056] S104, under the guidance of the model, the sand body period and superimposed relationship of the target layer are predicted, the longitudinal resolution of the sand body is controlled by applying the well data, the lateral resolution of the sand body is controlled by applying the seismic data, and the high-precision sand body configuration identification and division are realized;

[0057] S105, the sand body classification research is carried out by applying the sand body configuration combination relationship, the reservoir comprehensive classification chart is established, and the unified standard for accurately identifying the relatively high-permeability “sweet spot” area of the development unit is provided.

[0058] As Figure 2 , the shallow water braided river delta plane sedimentary model of the research area is studied, the macro and micro data such as outcrop, core, drilling and microscopic observation are collected and classified and analyzed, and it is found by combing that the sedimentary environment of the research area is a gentle slope depression lake basin, the climate is generally dry, the lake water is shallow, the channel is mostly filled with structure, and the shallow water braided river delta sediment is developed in the research area, and thus the shallow water braided river delta plane sedimentary model of the research area is established.

[0059] Based on the theory of sequence stratigraphy such as the chronological stratigraphic framework, the internal stratum of the sedimentary sequence and the lithofacies distribution model, the sedimentary cycle of the target layer is analyzed, and the sedimentary system domain of the three-level base level cycle is determined by combining the well and seismic data in the idea of point-line-plane.

[0060] On the “point”, the GR and AC logging curves can well reflect the change of the stratum lithology by combining the internal stratum of the sedimentary sequence according to the characteristics of the single well logging curve, and the Shaximiao Formation can be divided into three three-level base level cycles according to the change trend, i.e., the bottom of the first member of Shaximiao Formation to the bottom of the second member of Shaximiao Formation is a falling cycle, the bottom of the second member of Shaximiao Formation to the bottom of the fourth member of Shaximiao Formation is a rising cycle, and the fourth member of Shaximiao Formation is a falling cycle;

[0061] On the "line," by combining the seismic facies characteristics of the profile with the distribution range of lithofacies, and through well-seismic calibration, it was found that the strong wave impedance difference caused the channel to form a strong seismic reflection. Above and below the interface of the Sha-21 and Sha-22 sub-members, the channels are relatively well-developed, and the channel reflection energy is strong and the channel scale is large. This indicates that the interface is the lowest position of the base level, forming an initial flooding surface (IFS) at the third-order sequence level. This sequence interface controls the distribution of the main channels. At the top of the Sha-23 sub-member, the channels are least developed, forming a maximum transgression interface (Mfs) at the third-order sequence level. Thus, the third-order sedimentary systems tract of the study area is determined.

[0062] On the surface, by combining planar seismic reflection characteristics with lithofacies distribution scale, it was found that the channel size and seismic reflection intensity have a good correlation. The channel sands of the Shaximiao Formation Phase 23 in the central Sichuan region were characterized. The amplitude attribute slices in the vertical direction were used to study the base surface variation characteristics of the strata. The results were consistent with the conclusions drawn from single well (point) and seismic profile (line) analysis, which once again accurately demonstrated the three-level base surface cycle.

[0063] like Figure 3 A vertical sedimentary model of shallow-water deltaic sequence stratigraphy is established. Under the constraints of the sedimentary systems tract, and based on the influence of the base surface on the accommodation space and the comprehensive sedimentary evolution background, the Shaximiao Formation is divided into three third-order base cycles from bottom to top, corresponding to three systems tracts: Lowstand Systems Tract (LST), Regressed Systems Tract (TST), and Highstand Systems Tract (HST).

[0064] like Figure 4 A lateral sedimentary model of shallow-water deltaic sequence stratigraphy was established. Analysis of the scale and pattern of sediments in plan and profile revealed that the target section, Sha-2-1, has a gentle slope and abundant sediment supply, exhibiting a foliate distribution in plan. The overall background is lacustrine regression, with sediments becoming coarser upwards. The sedimentary type is mainly reverse S-type progradational sequence. The accommodation space is low, and the channel sand bodies are mostly laterally and vertically cut and superimposed on each other. The sand body deposition is multi-layered and laterally superimposed. Based on this, a lateral sedimentary model of shallow-water deltaic sequence stratigraphy was established.

[0065] The vertical resolution of sand bodies is controlled by well logging curve features, the horizontal resolution of sand bodies is controlled by seismic reflection features, and the distribution range of sand bodies is controlled by the P-wave and S-wave velocity ratio inversion features. The combination of these three methods achieves high-precision sand body configuration identification and division, and clarifies the superposition relationship of the scale of channel sand body profiles.

[0066] like Figure 5 The reservoir comprehensive classification chart model divides sand bodies into three categories based on sand body configuration characteristics and single-well productivity, combined with sand body rhythm: homogeneous, homogeneous + composite, and composite. This establishes a comprehensive reservoir classification chart, providing a unified standard for accurately identifying relatively high-permeability "sweet spots" in development units.

[0067] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood that modifications can be made to the foregoing embodiments, or additional implementations can be implemented, without departing from the spirit and scope of the inventive subject matter. Accordingly, the present application is not limited to the implementations described herein, but is intended to be defined by the claims set forth below, and equivalents thereof.

Claims

1. A method for morphological analysis of shallow-water deltaic sand bodies based on sequence stratigraphic sedimentary models, characterized by: Includes the following steps: Based on the geological background, a planar sedimentary model of shallow-water braided river delta in the study area was established. Determine the three-level reference level cyclic depositional system tract; Based on sequence stratigraphy theory, the sedimentary cycles of the target section are analyzed, and the sedimentary system tract of the three-level reference surface cycle is determined by combining well and seismic analysis with a point-line-surface approach. The method of using a point-line-surface approach to determine the third-level base-level cycle sedimentary system tract through well-seismic combination includes: at the "point" level, determining the third-level base-level cycle of the target interval by combining the characteristics of single-well logging curves with the internal strata of the sedimentary sequence; at the "line" level, determining the third-level sedimentary system tract by combining the seismic facies characteristics of the profile with the lithofacies distribution range; and at the "surface" level, verifying the third-level base-level cycle again by combining the planar seismic reflection characteristics with the lithofacies distribution scale. Under the constraints of the sedimentary system tract, the scale and pattern of sediment planes and profiles are analyzed based on the changes in the base level, and a vertical and horizontal sedimentary model of shallow-water deltaic sequence stratigraphy is established. Based on the vertical and horizontal sedimentary models of shallow-water delta sequence stratigraphy, the target layer sand body phases and superposition relationships are predicted, and the sand body resolution is controlled to achieve sand body configuration identification and division with different precision. Sandbody classification studies were conducted using sandbody configuration relationships, and a comprehensive reservoir classification chart was established.

2. The method for shallow-water deltaic sandbody configuration based on sequence stratigraphic sedimentary models as described in claim 1, characterized in that: Based on the geological background, data from outcrops, cores, wells, and microscopic observations were collected, classified, and analyzed to sort out the paleotectonic and paleoclimatic sedimentary environments of the study area, and to predict and establish a planar sedimentary model for shallow-water braided river deltas in the study area.

3. The method for shallow-water deltaic sandbody configuration based on sequence stratigraphic sedimentary models as described in claim 1, characterized in that: Under the constraints of the sedimentary system domain, and based on the influence of the reference surface on the accommodative space, the scale and pattern of sedimentary profiles are analyzed to establish a vertical sedimentary model for shallow-water deltaic sequence stratigraphy.

4. The method for shallow-water deltaic sandbody configuration based on sequence stratigraphic sedimentary models as described in claim 1, characterized in that: Under the constraints of the sedimentary system domain, the scale and pattern of sediment planes and profiles are analyzed based on the changes in the base level, as well as the impact of the changes in the base level on the accommodative space, to establish a lateral sedimentary model of shallow-water deltaic sequence stratigraphy.

5. The method for shallow-water deltaic sandbody configuration based on sequence stratigraphic sedimentary models as described in claim 1, characterized in that: The control of sand body resolution enables the identification and division of sand body configurations with different levels of precision. Three methods are used, including: using well logging curve features to control the longitudinal resolution of sand bodies, using seismic reflection features to control the lateral resolution of sand bodies, and using P-wave and S-wave velocity ratio inversion features to control the distribution range of sand bodies.

6. The method for shallow-water deltaic sandbody configuration based on sequence stratigraphic sedimentary models as described in claim 1, characterized in that: Based on the sand body configuration characteristics and single-well productivity, and combined with the sand body rhythm, the sand bodies are divided into three categories, thereby establishing the comprehensive reservoir classification chart.

7. The method for shallow-water deltaic sandbody configuration based on sequence stratigraphic sedimentary models as described in claim 6, characterized in that: The sand bodies are classified into three types: homogeneous, homogeneous + composite, and composite.

8. A shallow-water deltaic sand body configuration system based on a sequence stratigraphic sedimentary model, characterized in that: include: The system comprises a first determining unit, a second determining unit, a third pattern unit, a fourth identification unit, and a fifth classification unit. The first determining unit is used to establish a planar sedimentary model of the shallow-water braided river delta in the study area based on the geological background. The second determining unit is used to determine the cyclic deposition system domain of the third-level reference surface; The second determining unit is used to: analyze the sedimentary cycles of the target section based on sequence stratigraphy theory, and determine the sedimentary system domain of the third-level reference surface cycle by combining well and seismic analysis with a point-line-surface approach; The second determining unit is specifically used for: at a "point", using the characteristics of single-well logging curves combined with the internal strata of sedimentary sequence to determine the third-level base surface cycle of the target interval; at a "line", using the characteristics of seismic profiles combined with the range of lithofacies distribution to determine the third-level sedimentary system tract; and at a "surface", using the characteristics of planar seismic reflections combined with the scale of lithofacies distribution to re-verify the third-level base surface cycle. The third model unit is used to analyze the scale and pattern of sediment planes and profiles based on changes in the base level under the constraints of the sedimentary system domain, and to establish vertical and horizontal sedimentary models of shallow-water deltaic sequence stratigraphy. The fourth identification unit is used to predict the sand body phases and superposition relationships of the target layer based on the vertical and horizontal sedimentary patterns of shallow-water delta sequence stratigraphy, control the sand body resolution, and realize the identification and division of sand body configurations with different precision. The fifth classification unit is used to conduct sand body classification research by applying the sand body configuration combination relationship and to establish a comprehensive reservoir classification map.

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