A method for constructing a geological framework model of a single sand body progradational structure in deltaic facies

Abstract

The present invention discloses a method for constructing a geological framework model of a single sand body progradational structure in a delta phase; including performing composite sand body dissection and sedimentary phase map drawing in combination with basic geological data; constructing a fault model; constructing a layer model based on the composite sand body dissection results and the sedimentary phase map; and realizing the construction of a framework model based on the layer model and the fault model. The present invention has the following advantages: based on the advantages of dense well network in the late stage of development, the present invention conducts fine dissection of the composite sand body in the delta phase, and uses the layering information of the single sand body on the well and the superposition relationship between the sand bodies to characterize the single sand body layer. The framework model constructed with the help of this layer can effectively guide fine geological modeling and lay the foundation for effective fitting of numerical models.

Description

Technical Field

[0001] The invention relates to a method for constructing a delta phase single sand body progradational structure geological framework model, and belongs to the field of oil and gas field development. Background Art

[0002] Deltas are a hot topic in sedimentology and a key target for oil and gas exploration. In the sedimentary evolution of this type of reservoir, sand bodies of different periods and microphases are stacked in space, and even evolve with fluvial sediments, resulting in complex and changeable structural relationships within the reservoir. Stratigraphic comparison may show the phenomenon of horizontal and oblique interlacing, which has an important impact on fluid migration. With the increasing degree of oilfield development year by year and the increasing density of well networks, fine geological modeling is an important part of development geological research.

[0003] The modeling level of previous delta phases is usually at the oil group level, and the seismic interpretation level is generally used as the modeling input level. This study aims to establish a model with accuracy to the single sand body level (average thickness of several meters to more than ten meters). Since seismic interpretation cannot be interpreted to this accuracy, and the single sand body progradational structure needs to be reasonably expressed in the geological model, this study focuses on the understanding of the geological model of composite sand bodies, divides them into single sand bodies, determines the sand body stages and superposition relationships developed in the composite sand bodies, and thus draws a sedimentary phase diagram, and describes the layer model of the single sand body through the contact relationship between the single sand bodies, thereby realizing the construction of the delta phase single sand body progradational structure framework. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a method for building a delta phase single sand body progradational structure geological framework model.

[0005] The present invention provides a method for constructing a delta phase single sand body progradational structure geological framework model, comprising the following steps:

[0006] 1) Combine basic geological data to dissect composite sand bodies and draw sedimentary facies maps;

[0007] 2) constructing a fault model based on the composite sand body dissection results in step 1);

[0008] 3) constructing a layer model based on the composite sand body dissection results and sedimentary phase diagram in step 1);

[0009] 4) Based on the layer model of step 3) and the fault model of step 2, the framework model is constructed.

[0010] The basic geological data of step 1) include seismic profiles, single well fluid data, well logging curves and comprehensive geological knowledge of the entire area.

[0011] Among them, the specific method of composite sand body dissection in step 1) is: using the well section and its corresponding seismic section in the vertical and parallel source direction, combined with the well fluid characteristics, natural gamma and resistivity logging curves, to divide the vertical development period of the single sand body in the composite sand body framework on the section; the composite sand body dissection result includes at least two sets of single sand bodies and the pre-depositional superposition relationship between sand bodies on the plane and / or section. The dissection result also includes the top and bottom surfaces of the composite sand body, which can be reflected in the sedimentary phase diagram.

[0012] The method for drawing the sedimentary phase diagram in step 1) is: combining the development characteristics of the reservoir on the plane, making the superposition relationship of each single sand body on the plane and the section meet the composite sand body dissection result, and obtaining the sedimentary phase diagram.

[0013] Wherein, in the step 2), Petrel 2020 software is used to build a fault model using conventional modeling methods such as the corner point grid method.

[0014] Among them, in the step 2), the specific method of building the fault model is: small fault processing, fault pillar direction processing, fault contact relationship processing, and fault gridding.

[0015] Among them, in the step 3), the layer model is constructed based on the top and bottom surfaces of the composite sand body, the single well stratification and the sedimentary phase diagram interpreted by the seismic interpretation, and its core is to make a reasonable single sand body interface inside the composite sand body.

[0016] Among them, in the step 3), taking the composite sand body s1 as an example, through the dissection of the composite sand body, n single sand bodies are subdivided, namely single sand body s1-1, single sand body s1-2, single sand body s1-3, ..., single sand body s1-n, where n is an integer greater than or equal to 3; taking the establishment of the top surface of the single sand body s1-2 as an example, the steps of building the layer model are as follows:

[0017] 31) s1-2 top surface point data set: the s1-3 top surface and the s1-2 bottom surface and the well point values ​​therein are combined as the s1-2 top surface difference point data set, and this range is the demarcated range;

[0018] 32) The method of taking the value of s1-2 outside the area demarcated in step 3 (1): Based on the fact that s1 and its internal sand bodies are progradational structures, let s1-2 be equal to the top surface of s1 when it is in contact with the top surface, and at the same time, let the bottom surface of s1-2 be equal to the bottom surface of s1;

[0019] 33) Interpolate to obtain the top surface of s1-2: Use virtual points to fit s1-2 outside the circled area to the top and bottom surfaces of s1, and collect them with the top surface points of s1-2 to obtain the top surface of s1-2;

[0020] Repeat the above method to obtain the top surface of each single sand body inside the composite sand body.

[0021] 9. The method for building a deltaic single sand body progradational structural geological framework model according to claim 1, characterized in that in the step 4), based on the layer model, each layer is split according to the requirements of the specific model grid size, thereby completing the construction of the framework model. The requirements of the specific model grid size can be set according to the actual needs of the user, and can also be set according to the commonly used sizes in the art.

[0022] In step 4), based on the layer model, the thickness of each well in the target layer is counted, where the maximum thickness of well A is X (m). If the modeling grid size is N (m), the number of layers in this layer is X / N. Each layer is layered according to this method to complete the construction of the framework model.

[0023] Due to the adoption of the above technical scheme, the present invention has the following advantages: based on the advantage of dense well network in the late stage of development, the present invention conducts fine dissection of the composite sand body of the delta phase, and uses the stratification information of the single sand body on the well and the superposition relationship between the sand bodies to characterize the single sand body layer. With the help of this layer, the framework model is built to effectively guide fine geological modeling and lay the foundation for effective fitting of numerical models. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic flow diagram of the method of the present invention;

[0025] Figure 2 is a cross-sectional view of the wells along the source direction in an embodiment of the present invention;

[0026] Figure 3 is a sedimentary phase diagram of the target layer in the study area in the embodiment of the present invention;

[0027] Figure 4 is a fault model diagram of the study area in an embodiment of the present invention;

[0028] Figure 5 This is a flow chart of the top surface construction of the sand body sand6-2 in the study area in the embodiment of the present invention;

[0029] Figure 6 It is a model diagram of the study area level in the embodiment of the present invention;

[0030] Figure 7 It is a framework model diagram of the study area in an embodiment of the present invention; DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but the embodiments should not be construed as limiting the present invention.

[0032] Summary of the invention: The present invention provides a method for constructing a delta phase single sand body progradational structure geological framework model, comprising the following steps:

[0033] 1. Composite sand body anatomy and sedimentary phase map drawing.

[0034] Combining seismic profiles, single well fluid data, logging curves and comprehensive geological knowledge of the entire area, the phase and superposition relationship of the single sand body is dissected for the composite sand body, and the corresponding sedimentary phase map is drawn. The steps for composite sand body dissection and sedimentary phase map drawing are as follows:

[0035] (1) Composite sand body anatomy: Using the well sections perpendicular to and parallel to the provenance direction and their corresponding seismic sections, combined with the well fluid characteristics, natural gamma and resistivity logging curves, the vertical development stages of single sand bodies within the composite sand body framework are divided on the sections.

[0036] (2) Sedimentary phase map drawing: Combined with the reservoir development characteristics on the plane, the superposition relationship of each single sand body on the plane and section meets the composite sand body anatomy results of step 1 (1).

[0037] 2. Construction of fault model.

[0038] The fault model was constructed using Petrel 2020 software and conventional modeling methods such as the corner point grid method. The specific methods include small fault processing, fault pillar direction processing, fault contact relationship processing, and fault gridding.

[0039] 3. Level model construction.

[0040] The core of the layer model construction is to make a reasonable single sand body interface inside the composite sand body. This method is constructed based on the top and bottom surfaces of the composite sand body, single well stratification and sedimentary phase diagram interpreted by seismic. The steps of layer model construction are as follows:

[0041] Taking the composite sand body s1 as an example, five single sand bodies are subdivided through the dissection of the composite sand body, and the top surface of the single sand body s1-2 is now established.

[0042] (1) s1-2 top surface point data set: The s1-3 top surface and the s1-2 bottom surface and the well point values ​​therein are combined as the s1-2 top surface difference point data set, and this range is the demarcated range;

[0043] (2) The method of taking the value of s1-2 outside the area demarcated in step 3 (1): Based on the fact that s1 and its internal sand body are progradational structures, let s1-2 be equal to the top surface of s1 when it is in contact with the top surface, and at the same time, let the bottom surface of s1-2 be equal to the bottom surface of s1.

[0044] (3) Interpolation to obtain the top surface of s1-2: Use virtual points to fit s1-2 outside the circled area to the top and bottom surfaces of s1, and then combine them with the top surface points of s1-2 to obtain the top surface of s1-2.

[0045] This method is used to obtain the top surfaces of each single sand body inside the composite sand body.

[0046] 4. Build the framework model.

[0047] Based on the layer model, each layer is split according to the requirements of the specific model grid size to complete the construction of the framework model. Based on the layer model, the thickness of each well in the target layer is counted, among which the maximum thickness of well A is X (m). If the modeling grid size is N (m), the number of layers in this layer is X / N. According to this method, each layer is layered to complete the construction of the framework model.

[0048] Example 1

[0049] like Figure 1 As shown, the present invention provides a method for constructing a delta phase single sand body progradational structural geological framework model, which is further illustrated by taking the A sand body of the S oil field in the Bohai Sea in eastern China as an example.

[0050] The A sand body of the S oil field is a braided river delta deposit. The A sand body is composed of 6 sets of composite sand bodies, sand1-sand6. The present invention adopts the following technical scheme to realize the construction of a single sand body progradational structural geological framework model of sand6 in the delta phase.

[0051] 1. Dissection of composite sand bodies and drawing of sedimentary phase maps.

[0052] Combining seismic profiles, single well fluid data, logging curves and comprehensive geological knowledge of the entire area, the period and superposition relationship of single sand bodies were dissected for the composite sand body, and the corresponding sedimentary facies diagram was drawn.

[0053] (1) Composite sand body anatomy: Using the parallel provenance direction to connect the well section and its corresponding seismic section, see Figure 2 , combined with the well fluid characteristics, natural gamma and resistivity logging curves, the vertical development stages of single sand bodies in the composite sand body framework were divided in the profile. Through the analysis and comparison of dozens of parallel and vertical provenance profiles, Sand6 dissected out 5 sets of single sand bodies, named Sand6-1, Sand6-2, Sand6-3, Sand6-4, Sand6-5. Figure 2 From the cross-section and configuration anatomy, it can be seen that sand6-1, sand6-2, sand6-3, and sand6-4 are in a frontal superposition relationship. Figure 3 The contact relationship on the plane can also be seen in the figure. Sand 6-5 is a sand body deposited at the same time as sand 6-1. The position relationship of each sand body is shown in the figure below. Figure 3 As shown, Figure 2 The sand bodies from sand6-1 to sand6-4 are shown to be superimposed and developed in a progradational structure.

[0054] (2) Sedimentary phase diagram drawing: Combine the reservoir development characteristics on the plane and the composite sand body dissection results of step 1 (1), consider the superposition relationship between the plane and the single sand body in the section, and draw the sand6 sedimentary phase diagram, such as Figure 3 As shown, Figure 3 This is a three-dimensional sedimentary phase diagram obtained by dissecting the composite sand body, which can reflect the five single sand bodies dissected in (1), where the dotted line is the lower boundary of the sand body and the solid line is the upper boundary of the sand body.

[0055] 2. Construction of fault model.

[0056] The fault model was constructed using Petrel 2020 software and conventional modeling methods such as the corner point grid method. The specific methods include small fault processing, fault pillar direction processing, fault contact relationship processing, and fault gridding. There are 8 faults in the study area, and conventional methods are used for fault modeling. Figure 4 , Figure 4 There are eight fault pillars when modeling faults in the petrel model. The figure shows the development and distribution relationship of faults, which is also one of the necessary steps in fault modeling.

[0057] 3. Level model construction.

[0058] The core of layer model construction is to make a reasonable single sand body interface inside the composite sand body. This method is constructed based on the top and bottom surfaces of the composite sand body, single well stratification and sedimentary phase diagram interpreted by seismic.

[0059] The composite sand body sand6 in the study area is subdivided into 5 single sand bodies through composite sand body dissection. Now take the establishment of the top surface of the single sand body sand6-2 as an example:

[0060] (1) sand6-2 top surface point data set: Figure 5 (a), the sand body of sand6-2 is the dotted line range, the sand body of sand6-3 is the solid line range, the top surface of sand6-3 (solid line on the left) and the bottom surface of sand6-2 (dashed line on the right) and the Z values ​​of the well points where the two lines intersect are combined as the data set of the difference points of the top surface of sand6-2, and this range is the demarcated range;

[0061] (2) Method for obtaining the value of sand6-2 outside the area delimited in step 3 (1): Based on the fact that sand6 and its internal sand bodies are progradational structures, let the left side of sand6-2 fit with the top surface and be equal to the top surface value of sand6, let the right side of the bottom surface of sand6-2 be equal to the bottom surface value of sand6, and use virtual points to fit sand6-2 with the top and bottom surfaces of sand6 outside the delimited area, see Figure 5 (b).

[0062] (3) Subtraction to obtain the top surface of sand6-2: Merge points (1) and (2) in step 3 and interpolate to obtain the top surface of sand6-2. Figure 5 (c).

[0063] Repeat the above method to obtain the top surface of each single sand body inside the composite sand body and obtain the layer model, such as Figure 6 shown.

[0064] 4. Build the framework model.

[0065] Based on the layer model, according to the requirements of specific model grid size (it can be based on the actual project needs and the size of the structure or sand body in the work area. For example, if precision is required, the research time is long, or the sand body is small, 10m*10m can be given, while if the project is more urgent or the sand body is large, 50m*50m can be given), each layer is split to complete the construction of the framework model.

[0066] The thickness of each well in the target layer is counted. The thickness of the sand body in sand6-2 of well A22 is the largest, which is 23.8 (m). If the modeling grid size is 1 (m), the number of layers in this layer is 24. According to this method, each layer is layered to complete the construction of the framework model. Figure 7 . Figure 7 For the general Figure 6 The layer model in the figure is layered according to the requirements of each 1m in the vertical direction, and a screenshot of the framework model is built. This model expresses the foreset superposition relationship of sand6-1, sand6-2, sand6-3, and sand6-4 analyzed in the plane and section above.

[0067] The present invention uses the anatomy of the composite sand body configuration as a constraint, and uses structural information such as the combination relationship and superposition pattern between single sand bodies within the reservoir to draw the top surface of the single sand body and reflect it in the geological model, which can effectively guide fine geological modeling.

[0068] The above embodiments are only used to illustrate the present invention, wherein the various steps of the method implementation can be changed, the structure of each component, the number of sections required for comparison in sand body anatomy and the setting of virtual points can be changed, and any equivalent transformations and improvements based on the technical solution of the present invention should not be excluded from the protection scope of the present invention.

[0069] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for constructing a delta phase single sand body progradational structural geological framework model, characterized in that: The steps include: 1) Combine basic geological data to dissect composite sand bodies and draw sedimentary facies maps; 2) Building a fault model based on the composite sand body dissection results in step 1); 3) constructing a layer model based on the composite sand body dissection results and sedimentary phase diagram in step 1); 4) Based on the layer model in step 3) and the fault model in step 2, the framework model is constructed; In the step 3), the layer model is constructed based on the top and bottom surfaces of the composite sand body interpreted by seismic interpretation, the single well stratification and the sedimentary phase diagram. The core is to make a reasonable single sand body interface inside the composite sand body; through the dissection of the composite sand body, n single sand bodies are subdivided, namely single sand body s1-1, single sand body s1-2, single sand body s1-3, ..., single sand body s1-n. Taking the establishment of the top surface of the single sand body s1-2 as an example, the steps of layer model construction are as follows: 31) s1-2 top surface point data set: the s1-3 top surface and the s1-2 bottom surface and the well point values ​​therein are combined as the s1-2 top surface difference point data set, and the collection range is the circled range; 32) Method for taking the value of s1-2 outside the area demarcated in step 3 (1): Based on the fact that s1 and its internal sand bodies are progradational structures, let s1-2 be equal to the top surface of s1 when it is in contact with the top surface, and at the same time, let the bottom surface of s1-2 be equal to the bottom surface of s1; 33) Interpolate to obtain the top surface of s1-2: Use virtual points to fit s1-2 outside the circled area to the top and bottom surfaces of s1, and then collect the top surface points of s1-2 to obtain the top surface of s1-2; Repeat the above method to obtain the top surface of each single sand body inside the composite sand body.

2. The method for constructing a delta phase single sand body progradational structural geological framework model according to claim 1, characterized in that: The basic geological data in step 1) include seismic profiles, single well fluid data, well logging curves and comprehensive geological knowledge of the entire area.

3. The method for constructing a delta phase single sand body progradational structure geological framework model according to claim 2, characterized in that: The specific method of composite sand body dissection in step 1) is: using the well-connected sections and their corresponding seismic sections in the vertical and parallel provenance directions, combined with the well fluid characteristics, natural gamma and resistivity logging curves, to divide the vertical development stages of single sand bodies within the composite sand body framework on the section; the composite sand body dissection results include at least two sets of single sand bodies on the plane and / or section and the progradational superposition relationship between sand bodies.

4. The method for constructing a delta phase single sand body progradational structural geological framework model according to claim 3, characterized in that: The method for drawing the sedimentary phase map in step 1) is: combining the development characteristics of the reservoir on the plane, making the superposition relationship of each single sand body on the plane and the section meet the composite sand body dissection result, and obtaining the sedimentary phase map.

5. The method for constructing a delta phase single sand body progradational structural geological framework model according to claim 1, characterized in that: In the step 2), Petrel 2020 software is used to build a fault model using a conventional modeling method of the corner point grid method.

6. The method for constructing a delta phase single sand body progradational structure geological framework model according to claim 5, characterized in that: In the step 2), the specific method of building the fault model is: small fault processing, fault pillar direction processing, fault contact relationship processing, and fault gridding.

7. The method for constructing a delta phase single sand body progradational structural geological framework model according to claim 1, characterized in that: In the step 4), based on the layer model, each layer is split according to the requirements of the specific model grid size, thereby completing the construction of the framework model.

8. The method for constructing a deltaic single sand body progradational structural geological framework model according to claim 7, characterized in that: In step 4), based on the layer model, the thickness of each well in the target layer is counted, where the maximum thickness of well A is X (m). If the modeling grid size is N (m), the number of layers in this layer is X / N. Each layer is layered according to this method to complete the construction of the framework model.

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