Shallow water delta sand body configuration method and system based on sequence stratigraphic deposition mode

Abstract

The invention relates to a shallow water delta sand body configuration method based on a sequence stratigraphic deposition mode, and belongs to the technical field of geological analysis, and the method comprises the following steps: establishing a shallow water braided river delta plane deposition mode of a research area; determining a three-level reference surface cycle deposition system domain; analyzing the scales and styles of sediment planes and profiles according to the change of the datum plane, and establishing longitudinal and transverse deposition modes of the shallow water delta sequence strata; sand body resolution is controlled, and identification and division of sand body configurations with different precisions are achieved; and carrying out sand body classification research by applying the sand body configuration combination relationship, and establishing a reservoir comprehensive classification chart. The invention further relates to a shallow water delta sand body configuration system based on the sequence stratigraphic deposition mode, the problems that how to accurately and efficiently predict the sand body space distribution form and scale of a strong heterogeneous reservoir and how to diversify sand body configuration prediction results due to personal subjective experience are solved, high-precision sand body configuration recognition and division are guided, and the construction efficiency is improved. And finally determining the longitudinal and transverse remaining oil distribution range.

Description

Technical Field

[0001] The invention belongs to the technical field of geological analysis, and in particular relates to a shallow water delta sand body configuration method and system based on a sequence stratigraphic deposition model. Background Art

[0002] Shallow braided river delta deposits are developed in large depression basins and fault basins in my country and are high-quality oil and gas resource reservoirs. Its typical sedimentary characteristics are extremely thick continental deposits and alternating distribution of sandstone and mudstone, which leads to strong vertical and horizontal heterogeneity of the reservoir. It is very difficult to finely characterize the boundaries of sand bodies and accurately predict wells. How to accurately and efficiently predict the spatial distribution morphology and scale of sand bodies in highly heterogeneous reservoirs has always been an important problem.

[0003] The key point of sand body architecture is to characterize the architecture interface of different levels and finally determine the vertical and horizontal distribution range of remaining oil. Conventional sand body architecture methods include field outcrops, core observations, logging data analysis, etc. However, for various sedimentary systems, the same process is often used to carry out sand body architecture level division, which has low research efficiency, and due to personal subjective experience, the prediction results are diverse and vary from person to person.

[0004] In order to maximize the uniformity of sand body architecture prediction results, it is crucial to establish a clear standard model for a certain type of sedimentary system to control the vertical and lateral boundaries and superposition relationships of sand bodies in the fine characterization of reservoirs. However, there is a lack of research on the establishment of standard vertical and lateral sedimentary models based on sequence stratigraphy to guide sand body architecture in shallow braided river delta sedimentary systems.

[0005] A lot of research has been done on sand body configuration methods in the prior art, but there are two shortcomings in the prior art: first, for different sedimentary systems, the same process is often used to carry out sand body configuration level division, the research efficiency is low, and due to personal subjective experience, the prediction results are diverse and vary from person to person; second, there is currently no idea to establish standard vertical and horizontal sedimentary models based on the principles of sequence stratigraphy for shallow braided river delta sedimentary systems, and to use unified standards to guide the study of high-precision sand body configuration. Summary of the invention

[0006] In response to the above problems, the present invention solves the problem of how to accurately and efficiently predict the spatial distribution morphology and scale of sand bodies in highly heterogeneous reservoirs, as well as the problem of diverse sand body configuration prediction results due to personal subjective experience, guides high-precision sand body configuration identification and division, and ultimately determines the vertical and horizontal remaining oil distribution range.

[0007] In order to overcome the problems existing in the prior art, the present invention provides the following technical solutions:

[0008] The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model includes the following steps:

[0009] According to the geological background, the planar sedimentary model of shallow braided river delta in the study area is established;

[0010] Determine the third-order base level cycle sedimentary system tract;

[0011] Under the constraints 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 vertical and horizontal sedimentary model of the shallow water delta sequence stratigraphy is established;

[0012] According to the vertical and horizontal sedimentary patterns of shallow water delta sequence stratigraphy, the sand body stages and superposition relationships of the target layer are predicted, the sand body resolution is controlled, and the sand body configuration identification and division with different precisions are realized;

[0013] Apply the sand body configuration combination relationship to carry out sand body classification research and establish a comprehensive reservoir classification map.

[0014] Furthermore, based on the geological background, the data collected from outcrops, cores, drilling and microscopic observations were classified and analyzed to sort out the paleo-tectonic and paleoclimate sedimentary environment of the study area, and to predict and establish the planar sedimentary model of the shallow braided river delta in the study area.

[0015] Furthermore, the target layer interval sedimentary cycle is analyzed based on sequence stratigraphic theory, and the third-level base level cycle sedimentary system domain is determined by combining well and seismic data with the idea of ​​point-line-plane.

[0016] Furthermore, the point-line-plane approach of combining well-seismic data to determine the third-level base-level cycle sedimentary system domain includes: on the "point", the third-level base-level cycle of the target layer is determined by combining the characteristics of the single well logging curve with the internal strata of the sedimentary sequence; on the "line", the third-level sedimentary system domain is determined by combining the profile seismic phase characteristics with the lithofacies distribution range; on the "surface", the third-level base-level cycle is verified again by combining the plane seismic reflection characteristics with the lithofacies distribution scale.

[0017] Furthermore, under the constraints of the sedimentary system domain, according to the influence of the base surface on the accommodation space, the scale and style of the sediment profile are analyzed to establish the vertical sedimentary model of the shallow water delta sequence stratigraphy.

[0018] Furthermore, under the constraints of the sedimentary system domain, the scale and style of the sediment plane and profile, as well as the impact of the base level change on the accommodation space are analyzed according to the change of the base level, and the lateral sedimentary model of the shallow water delta sequence stratigraphy is established.

[0019] Furthermore, the control of sand body resolution realizes identification and division of sand body configurations with different accuracies using three methods, including: applying logging curve characteristics to control the vertical resolution of sand bodies, seismic reflection characteristics to control the lateral resolution of sand bodies, and longitudinal and transverse wave velocity ratio inversion characteristics to control the distribution range of sand bodies.

[0020] Furthermore, according to the sand body configuration characteristics and single well productivity, the sand bodies are divided into three categories in combination with the sand body rhythm, thereby establishing the comprehensive reservoir classification chart.

[0021] Furthermore, the sand bodies are divided into three categories, including uniform type, uniform + composite type, and composite type.

[0022] A shallow water delta sand body configuration system based on sequence stratigraphic depositional patterns, comprising: a first determination unit, a second determination unit, a third pattern unit, a fourth identification unit and a fifth classification unit;

[0023] The first determination unit is used to establish a planar sedimentation model of a shallow braided river delta in a study area according to the geological background;

[0024] The second determination unit is used to determine the third-order base level cycle sedimentary system tract;

[0025] The third model unit is used to analyze the scale and style of the sediment plane and profile according to the change of the base level under the constraint of the sedimentary system domain, and establish the vertical and horizontal sedimentary model of the shallow water delta sequence stratigraphy;

[0026] The fourth identification unit is used to predict the sand body stages and superposition relationships of the target layer according to the vertical and horizontal sedimentary patterns of the shallow water delta sequence strata, control the sand body resolution, and realize the identification and division of sand body configurations with different precisions;

[0027] The fifth classification unit is used to apply the sand body configuration combination relationship to carry out sand body classification research and establish a comprehensive reservoir classification map.

[0028] The beneficial effects of the present invention are as follows: the present invention targets highly heterogeneous reservoirs in shallow braided river delta sedimentary systems, comprehensively utilizes macroscopic and microscopic data such as field outcrops, core observations, microscopic analysis, and seismic phases, and establishes a standard model of vertical and horizontal deposition of reservoirs based on the principle of sequence stratigraphy to control the vertical and horizontal boundaries of sand bodies, thereby guiding high-precision sand body configuration identification and division; based on the principle of sequence stratigraphy, a standard model of vertical and horizontal deposition of reservoirs is established to control the vertical and horizontal boundaries of sand bodies, thereby guiding high-precision sand body configuration identification and division, and ultimately determining the vertical and horizontal distribution range of remaining oil, which has important application significance for the detailed description of oil reservoirs in the development stage.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A flow chart of the configuration method implementation of the present invention is shown;

[0032] Figure 2 A schematic diagram of a shallow braided river delta depositional model according to an embodiment of the present invention is shown;

[0033] Figure 3 A schematic diagram of the vertical depositional pattern of a shallow braided river delta sequence stratum according to an embodiment of the present invention is shown;

[0034] Figure 4 A schematic diagram of the lateral depositional pattern of a shallow braided river delta sequence stratum according to an embodiment of the present invention is shown;

[0035] Figure 5 A schematic diagram of a classification chart of shallow water braided river delta sand bodies according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0036] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

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

[0040] like Figure 1 According to the implementation flow chart, the present invention proposes a shallow water delta sand body configuration method based on the sequence stratigraphic deposition model, and the process is as follows:

[0041] According to the geological background, outcrop, drilling, core and other data were collected to sort out the geological background of the study area and establish the planar sedimentary model of shallow braided river delta in the study area;

[0042] Hierarchical control: Determine the third-level base level cyclic sedimentary system domain based on the single well logging curve characteristics, profile seismic reflection characteristics, and planar river channel scale characteristics;

[0043] Sequence constraints: Under the constraints 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 impact of the base level change on the accommodation space, and the vertical and horizontal sedimentary model of the shallow water delta sequence stratigraphy is established;

[0044] Combination of well and seismic data: predict the sand body stages and superposition relationships of the target layer based on the vertical and horizontal sedimentary patterns of the shallow water delta sequence strata, control the sand body resolution, and realize the identification and division of sand body configurations with different precisions;

[0045] Dynamic verification: Apply the sand body configuration combination relationship to carry out sand body classification research, establish a comprehensive reservoir classification map, and provide standards for accurately identifying relatively high permeability areas in development units.

[0046] A shallow water delta sand body configuration system based on sequence stratigraphic depositional patterns is also provided, comprising: a first determination unit, a second determination unit, a third pattern unit, a fourth identification unit, and a fifth classification unit;

[0047] The first determination unit is used to establish a planar sedimentation model of a shallow braided river delta in a study area according to the geological background;

[0048] The second determination unit is used to determine the third-order base level cycle sedimentary system tract;

[0049] The third model unit is used to analyze the scale and style of the sediment plane and profile according to the change of the base level under the constraint of the sedimentary system domain, and establish the vertical and horizontal sedimentary model of the shallow water delta sequence stratigraphy;

[0050] The fourth identification unit is used to predict the sand body stages and superposition relationships of the target layer according to the vertical and horizontal sedimentary patterns of the shallow water delta sequence strata, control the sand body resolution, and realize the identification and division of sand body configurations with different precisions;

[0051] The fifth classification unit is used to apply the sand body configuration combination relationship to carry out sand body classification research and establish a comprehensive reservoir classification map.

[0052] In this embodiment, the sand body configuration of the Jurassic Shaximiao Formation in the oblique gentle belt depression of the central Sichuan paleo-high in the Sichuan Basin is taken as an example to further explain the patent of the present invention in detail.

[0053] S101 uses outcrop, drilling and core data to sort out the geological background of the study area and determine the planar sedimentary model of shallow braided river delta;

[0054] S102 is based on the theory of sequence stratigraphy and combines well and seismic data to determine the third-level base level cyclic sedimentary system domain with the idea of ​​point-line-plane;

[0055] S103: Under the constraints 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 vertical and horizontal sedimentary model of the shallow water delta sequence stratigraphy is established;

[0056] S104 predicts the target layer sand body stage and superposition relationship under the guidance of the model, and uses well data to control the vertical resolution of the sand body and seismic data to control the lateral resolution of the sand body, thus achieving high-precision sand body configuration identification and division;

[0057] S105 uses the combination relationship of sand body configuration to carry out sand body classification research, establish a comprehensive reservoir classification map, and provide a unified standard for accurately identifying the relatively high-permeability "sweet spot" areas of development units.

[0058] like Figure 2 , the planar sedimentary model of the shallow braided river delta in the study area was developed, and macro and micro data such as outcrops, cores, drilling and microscopic observations were collected and classified and analyzed. It was found that the sedimentary environment of the study area is a gentle slope depression lake basin, the climate is generally dry, the lake basin water is shallow, and there are many filling structures in the river channel. It is determined that shallow braided river delta deposits are developed in the study area, and thus the planar sedimentary model of the shallow braided river delta in the study area is established.

[0059] The sedimentary cycles of the target intervals are analyzed based on the sequence stratigraphic theory, such as the chronostratigraphic framework, internal strata of the sedimentary sequence, and lithofacies distribution patterns. The third-level base level cycle sedimentary system domain is determined by combining well and seismic data with the idea of ​​point-line-plane.

[0060] At the "point", the GR and AC logging curves can better reflect the lithological changes of the formations by combining the characteristics of single well logging curves with the internal strata of the sedimentary sequence. According to their changing trends, the Shaximiao Formation can be divided into three third-level base level cycles: the bottom of the first section of Shahejie Formation to the bottom of the second section of Shahejie Formation is a descending cycle, the bottom of the second section of Shahejie Formation to the bottom of the fourth section of Shahejie Formation is an ascending cycle, and the fourth section of Shahejie Formation is a descending cycle;

[0061] On the "line", based on the seismic phase characteristics of the profile and the distribution range of the lithofacies, through well-seismic calibration, it was found that the strong wave impedance difference caused the river channel to form a strong seismic reflection. Above and below the interface of the Sha21 and Sha22 sub-members, the river channel is relatively developed, and the river channel reflection energy is strong and the river channel scale is large, indicating that the interface is the lowest position of the base level, forming an initial lake flooding surface (IFS) of the third-order sequence level. This sequence interface controls the distribution of the main river channels; at the top of the Sha23 sub-member, the river channel is the least developed, forming a maximum water transgression interface (Mfs) of the third-order sequence level, thereby determining the third-order sedimentary system domain in the study area.

[0062] On the "surface", by combining the planar seismic reflection characteristics with the lithofacies distribution scale, it was found that the river channel scale has a good correlation with the seismic reflection intensity. The 23rd river channel sandstone group of the Shaximiao Formation in the central Sichuan area was characterized, and the base level change characteristics of the strata were studied by vertical amplitude attribute slices, which are consistent with the conclusions drawn from the single well (point) and seismic profile (line) analysis, once again accurately demonstrating the third-level base level cycle.

[0063] like Figure 3 , the vertical sedimentary model of shallow-water delta sequence stratigraphy. Under the constraints of the sedimentary system domain, according to the influence of the base surface on the accommodation space and the comprehensive sedimentary evolution background, the Shaximiao Formation is divided into three third-level base cycles from bottom to top, corresponding to three system domains: lowstand system domain (LST), regressive system domain (TST), and highstand system domain (HST), and the vertical sedimentary model of shallow-water delta sequence stratigraphy is established.

[0064] like Figure 4 , the lateral sedimentary model of shallow-water delta sequence strata, analyzing the scale and style of sediment plane and section, it is found that the slope of the target layer segment Sha 2 1 is gentle, the sediment supply is sufficient, and the plane is distributed in a leaf-like shape; the overall background is lake regression, the sediments become coarser upward, and the sedimentary type is mainly an inverted S-type progradational sequence; the accommodation space is low, and the river channel sand bodies are mostly cut and superimposed on each other laterally and vertically, and the sand body deposition is a multi-layer lateral superposition, thus establishing the lateral sedimentary model of shallow-water delta sequence strata.

[0065] The vertical resolution of sand bodies is controlled by logging curve characteristics, the lateral resolution of sand bodies is controlled by seismic reflection characteristics, and the distribution range of sand bodies is controlled by the inversion characteristics of the longitudinal and transverse wave velocity ratios. The three methods are combined to achieve high-precision identification and division of sand body configurations, and clarify the scale and superposition relationship of the river channel sand body profile.

[0066] like Figure 5 The comprehensive reservoir classification chart model divides the sand bodies into three categories according to the sand body configuration characteristics and single well production capacity combined with the sand body rhythm: uniform type, uniform + composite type, and composite type. In this way, a comprehensive reservoir classification chart is established, providing a unified standard for accurately identifying the relatively high permeability "sweet spot" areas of development units.

[0067] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model, characterized by: The following steps are involved: According to the geological background, the planar sedimentary model of shallow braided river delta in the study area is established; Determine the third-order base level cycle sedimentary system tract; Under the constraints 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 vertical and horizontal sedimentary model of the shallow water delta sequence stratigraphy is established; According to the vertical and horizontal sedimentary patterns of shallow water delta sequence stratigraphy, the sand body stages and superposition relationships of the target layer are predicted, the sand body resolution is controlled, and the sand body configuration identification and division with different precisions are realized; Apply the sand body configuration combination relationship to carry out sand body classification research and establish a comprehensive reservoir classification map.

2. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 1, characterized in that: Based on the geological background, the data collected from outcrops, cores, drilling and microscopic observations were classified and analyzed to sort out the paleo-tectonic and paleoclimate sedimentary environment of the study area, and the planar sedimentary model of the shallow braided river delta in the study area was predicted and established.

3. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 1, characterized in that: The target layer sedimentary cycle is analyzed based on sequence stratigraphy theory, and the third-level base level cycle sedimentary system domain is determined by combining well and seismic data with the idea of ​​point-line-plane.

4. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 3, characterized in that: The point-line-plane approach of combining well and seismic data to determine the third-level base level cycle sedimentary system domain includes: on the "point", the third-level base level cycle of the target layer is determined by combining the characteristics of the single well logging curve with the internal strata of the sedimentary sequence; on the "line", the third-level sedimentary system domain is determined by combining the characteristics of the profile seismic facies with the distribution range of the lithofacies; on the "plane", the third-level base level cycle is verified again by combining the plane seismic reflection characteristics with the distribution scale of the lithofacies.

5. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 1, characterized in that: Under the constraints of the sedimentary system domain, according to the influence of the base surface on the accommodation space, the scale and style of the sediment profile are analyzed, and the vertical sedimentary model of the shallow water delta sequence stratigraphy is established.

6. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 1, characterized in that: Under the constraints of the sedimentary system domain, the scale and style of the sediment plane and profile, as well as the impact of the base level change on the accommodation space are analyzed according to the change of the base level, and the lateral sedimentary model of the shallow water delta sequence strata is established.

7. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 1, characterized in that: The sand body resolution is controlled to realize the identification and division of sand body configurations with different precisions, using three methods, including: applying logging curve characteristics to control the vertical resolution of the sand body, seismic reflection characteristics to control the lateral resolution of the sand body, and longitudinal and transverse wave velocity ratio inversion characteristics to control the sand body distribution range.

8. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 1, characterized in that: According to the sand body configuration characteristics and single well productivity, combined with the sand body rhythm, the sand bodies are divided into three categories, thereby establishing the comprehensive classification chart of the reservoir.

9. The shallow water delta sand body configuration method based on sequence stratigraphic sedimentation model according to claim 8, characterized in that: The sand bodies are divided into three categories, including uniform type, uniform + composite type, and composite type.

10. A shallow water delta sand body architecture system based on sequence stratigraphic sedimentation model, characterized by: include: a first determining unit, a second determining unit, a third pattern unit, a fourth identifying unit, and a fifth classifying unit; The first determination unit is used to establish a planar sedimentation model of a shallow braided river delta in a study area according to the geological background; The second determination unit is used to determine the third-order base level cycle sedimentary system tract; The third model unit is used to analyze the scale and style of the sediment plane and profile according to the change of the base level under the constraint of the sedimentary system domain, and establish the vertical and horizontal sedimentary model of the shallow water delta sequence stratigraphy; The fourth identification unit is used to predict the sand body stages and superposition relationships of the target layer according to the vertical and horizontal sedimentary patterns of the shallow water delta sequence strata, control the sand body resolution, and realize the identification and division of sand body configurations with different precisions; The fifth classification unit is used to apply the sand body configuration combination relationship to carry out sand body classification research and establish a comprehensive reservoir classification map.

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