A method for preparing a complex structural geological model based on lithofacies distribution

Abstract

The present invention provides a method for preparing a complex structural geological model based on lithofacies distribution, the method comprising the following steps: establishing a three-dimensional layer model according to seismic and layered data, determining the model basement, target layer and top layer; establishing a three-dimensional lithofacies model using core and logging data, determining the lithofacies type, top and bottom heights and boundaries of each layer; scaling the model size to the test conditions in proportion according to the similarity principle, obtaining each layer and lithofacies boundary of the model using 3D printing technology, and preparing a formation mold containing lithofacies distribution; conducting downhole core component analysis and particle size analysis of different lithofacies, obtaining different lithofacies component information, each component content and particle size distribution, determining casting materials and their components and particle size distribution; casting and molding from bottom to top layer by layer. The present invention solves the problem of incomplete consideration of lateral rock mechanical parameters of existing models by low-cost and high-precision means, and improves the accuracy of model tests.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas exploration and development, and particularly to a method for preparing a complex structural geological model based on lithofacies distribution. Background Art

[0002] Lithofacies controls the microscopic structure, fabric, mineral composition, and particle characteristics of sediments, etc., thus resulting in certain regional differences in the mechanical properties of reservoir rocks or rock masses. It controls the macroscopic distribution of the mechanical parameters of the reservoir and can be used as the basis for dividing the heterogeneity at the reservoir scale of oil and gas reservoirs. Therefore, establishing a large-scale geological model based on lithofacies distribution has important engineering practical significance for carrying out geomechanics research on oil and gas reservoirs. The preparation of conventional large-scale geological models scales the target block to indoor conditions based on the similarity principle and uses similar materials for layer-by-layer pouring. This method has the advantages of convenient material modification and fewer restrictions on raw materials, such as using epoxy resin and silicone rubber simulation materials, and using mixed materials such as cement and quartz sand. However, this method fails to consider the changes in the mechanical properties of the model in the horizontal direction of a single formation, resulting in a large difference between the deformation characteristics and failure instability modes of the model when stressed and the actual situation. In recent years, the method of using 3D printers to prepare formation physical models has gradually matured, which can better realize the three-dimensional heterogeneity of the model, and this method has the advantages of good geometric adaptability, high reduction degree of the formation model, and high efficiency and convenience. For example, cement (gypsum)-based material 3D printing technology is usually used to prepare large-scale rock mass physical models. However, this technology has the disadvantages of low precision, difficult control of material properties, and high costs for equipment cleaning and maintenance.

[0003] Therefore, a method for preparing a complex structural geological model that can reflect lithofacies distribution is needed to solve the problem of the change of horizontal mechanical parameters of the formation at the reservoir scale of oil and gas reservoirs, and a model preparation method with low cost, high precision, and easy control of materials is needed to improve the accuracy and preparation efficiency of model test results. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present application proposes a method for preparing a complex structural geological model based on lithofacies distribution, which solves the problem of incomplete consideration of horizontal rock mechanical parameters of existing models with low-cost and high-precision means, and improves the accuracy of model tests.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] One of the purposes of the present application is to provide a method for preparing a complex structural geological model based on lithofacies distribution, including the following preparation steps:

[0007] S1, establish a three-dimensional layer model based on seismic and stratification data, and determine the model base, target layer, and top layer;

[0008] S2. Establish a three-dimensional lithofacies model using core and logging data to determine the lithofacies types, top and bottom heights, and boundaries of each horizon;

[0009] S3. Scale the model size proportionally to the experimental conditions according to the similarity principle, and use 3D printing technology to obtain the horizons and lithofacies boundaries of the model, and prepare a formation mold with lithofacies distribution;

[0010] S4. Conduct downhole core component analysis and particle size analysis of different lithofacies to obtain different lithofacies component information, the content of each component, and particle size distribution, and determine the casting material, its components, and particle size distribution;

[0011] S5. Cast and form layer by layer from bottom to top.

[0012] Furthermore, the implementation method of step S1 is as follows:

[0013] Pour the horizon spatial coordinate data into professional geological modeling software, plan the research scope of the target block, and perform regular cutting. Interpolate the horizon data to obtain the bedding data, and use the stratified data to adjust the local structural positions of the bedding. Finally, project the bedding longitudinally onto a plane to construct a three-dimensional structural model including the top and bottom layers.

[0014] Furthermore, the implementation method of step S2 is as follows:

[0015] S2.1 Divide the lithofacies types in the study area according to the rock combination characteristics, logging data, and combined with the regional sedimentary tectonic background, and convert a series of facies into codes;

[0016] S2.2 Use logging data to identify lithofacies, construct the principal component equation related to lithofacies, and use artificial intelligence algorithms to predict the lithofacies types of single wells and construct a single-well lithofacies distribution model;

[0017] S2.3 Use the interpolation method to perform spatial interpolation on the single-well lithofacies prediction results, establish a three-dimensional structural model based on lithofacies distribution, and determine the lithofacies boundary and thickness of each layer;

[0018] Furthermore, the implementation method of step S4 is as follows:

[0019] Collect downhole rock samples of different lithofacies on site, and analyze the mineral components, mineral content, and particle size distribution range of different types of rock particles through XRD tests and cast thin sections;

[0020] Furthermore, the specific implementation method of step S5 is as follows:

[0021] S5.1 Determine the casting raw materials according to the mineral component content and particle size distribution of different lithofacies obtained in step S4;

[0022] S5.2 Mix the mineral particles of different lithofacies according to the mineral type and content to obtain mixtures of different lithofacies;

[0023] S5.3 Put the mixture into the test box to simulate the bedrock layer, then arrange the printed third-layer formation mold on the bedrock layer, and pour the mixed mixture into the formation mold according to the lithofacies, controlling the filling amount to be slightly higher than the mold thickness;

[0024] S5.4 Place the second-layer formation mold and apply pressure until the material is completely compacted, cemented and consolidated;

[0025] S5.5 Let it stand at room temperature and then demold;

[0026] S5.6 Repeat steps S5.3 - S5.5 until the artificially prepared formations in the mold are gradually compacted and lithified layer by layer, and cure them under the conditions of a certain temperature and natural drying until completely dry. After preparation is completed, a complex structural geological model based on lithofacies distribution is obtained;

[0027] Furthermore, the pressure applied in step S5.4 is the vertical stress applied by the overlying rock formation;

[0028] The standing time in step S5.5 is 2 h;

[0029] The curing time in step S5.6 is 7 d, and the curing temperature is 10 - 30 °C;

[0030] Even further, the curing temperature in step S5.6 is 20 °C;

[0031] The second object of the present invention is to provide a complex structural geological model prepared by the said preparation method.

[0032] The preparation method of the complex structural geological model based on lithofacies distribution provided by the present invention includes: establishing a three-dimensional layer model according to seismic and stratification data to determine the model basement, target layer and top layer; establishing a three-dimensional lithofacies model using core and logging data to determine the lithofacies types, top and bottom heights and boundaries of each layer; scaling the model size proportionally to the test conditions according to the similarity principle, and using 3D printing technology to obtain the layers and lithofacies boundaries of the model, and preparing a formation mold containing lithofacies distribution; scaling the model size proportionally to the test conditions according to the similarity principle, and using 3D printing technology to obtain the layers and lithofacies boundaries of the model, and preparing a formation mold containing lithofacies distribution; pouring and molding layer by layer from bottom to top. Through the said method, the problem of the change of lateral mechanical parameters of the formation at the reservoir scale of the oil and gas reservoir can be solved, and the problem that the lateral rock mechanical parameters of the existing model are not fully considered can be solved by means of low cost and high precision, and the accuracy of the model test can be improved. Description of the Drawings

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0034] Figure 1 It is the preparation flow chart of the present invention;

[0035] Figure 2 It is a three-dimensional layer model including the top and bottom layers;

[0036] Figure 3 It is a three-dimensional lithofacies distribution model. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the following further details the present invention in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] This embodiment provides a method for preparing a complex structural geological model based on lithofacies distribution, as Figure 1 shown, including the following steps:

[0039] Step 1: Establish a three-dimensional layer model based on seismic and stratigraphic data, and determine the model base, target layer and top layer. The specific method is as follows:

[0040] (1) Import the horizon spatial coordinate data (i, j, k) into the Petrel three-dimensional geological modeling software, plan the research scope of the target block, and perform regular cutting. The obtained research area range is 13800×8500×140m;

[0041] (2) Interpolate the horizon data to obtain regularized horizon data, and use the stratigraphic data to adjust the local structure position of the horizon. Finally, project the horizon longitudinally onto a plane to construct a three-dimensional layer model including the top and bottom layers, as Figure 2 shown;

[0042] Step 2: Establish a three-dimensional lithofacies model using core and logging data, and determine the lithofacies types, top and bottom heights and boundaries of each horizon. The specific steps are as follows:

[0043] (1) Analyze the petrological characteristics of the formation as tight sandstone using core data. According to the lithology, it can be divided into mudstone, feldspar lithic sandstone, lithic sandstone and lithic quartz sandstone. Convert the above lithologies into codes of 0, 1, 2, and 3 respectively;

[0044] (2) Compare core data with logging data, and optimize 5 lithology-sensitive curves: GR, AC, DEN, CNL, and RD. Use the neural network algorithm to perform single-well prediction of lithofacies distribution;

[0045] (3) Perform spatial interpolation on the single-well lithofacies prediction results, establish a three-dimensional lithofacies distribution model, and determine the lithofacies boundary and thickness of each layer, as Figure 3 shown;

[0046] Step 3: Scale the model size proportionally to the test conditions according to the similarity principle, and use 3D printing technology to obtain each layer and lithofacies boundary of the model, and prepare a formation mold containing lithofacies distribution;

[0047] Step 4: Carry out downhole core component analysis and particle size analysis of different lithofacies, obtain different lithofacies component information, the content of each component and particle size distribution, and determine the casting material and its components and particle size distribution;

[0048] Carry out component analysis and particle size analysis on the core samples of the target layer. It is determined that the main rock minerals are quartz, feldspar, and metamorphic rock cuttings, with a small amount of clay minerals. The mineral contents of different lithofacies are shown in Table 1. Among them, for mudstone compared with sandstone, the quartz content is the least, 50.6%, the feldspar and clay mineral contents are relatively high, 26.7% and 17.8% respectively, with a small amount of cuttings, and the particle size is 0.01 - 0.0156mm; the average quartz content of feldspar lithic sandstone is 64.5%, the feldspar content is 12.6%, the cuttings content is 17.8%, and the particle size is mainly extremely fine - fine grain particle structure, 0.0625 - 0.2mm; the quartz content of lithic sandstone is 65.6%, the feldspar content is 10.9%, the highest cuttings content is 20.6%, and the particle size is mainly (gravel) coarse grain particle structure, 0.5 - 2mm; the highest quartz content of lithic quartz sandstone is 78.7%, the cuttings content is 13%, with a small amount of feldspar and clay minerals, and the particle size is mainly coarse - medium grain, 0.25 - 0.5mm;

[0049] Step 5: Pour and form layer by layer from bottom to top. The specific steps are as follows:

[0050] (1) Mixing: According to the analysis results in Table 1, obtain quartz sand, feldspar, cuttings, and clay with different particle sizes, and add them to the mixer in sequence according to the component content, mix dry evenly, then slowly pour the aqueous solution, and continue to mix for 10 minutes to obtain mixtures of different lithofacies;

[0051] (2) Loading: First, load the mixture of lithic sandstone into the test box to simulate the bedrock layer, then place the printed third-layer formation mold on the bedrock layer, and pour the mixed material into the formation mold according to the lithofacies category, and control the loading amount slightly higher than the mold thickness;

[0052] (3) Compression: Place the second-layer formation mold and apply pressure. The applied pressure is 80 MPa until the material is completely compacted, cemented, and consolidated.

[0053] (4) Demolding: Leave it standing for 2 h at room temperature and then demold.

[0054] (5) Repeat steps (2) to (4) until the artificially prepared formations in the mold are gradually compacted, cemented, and lithified. Place it under the conditions of room temperature around 20°C and natural drying for curing for 7 d until it is completely dry. The preparation is completed to obtain a complex structural geological model based on lithofacies distribution.

[0055] Table 1 Average mineral component content and particle size distribution table of each lithofacies in the target layer

[0056] Lithofacies Quartz (%) Feldspar (%) Clay Minerals (%) Detritus (%) Grain Size (mm) Shale 50.6 26.7 17.8 3.5 0.01～0.0156 Arkose 64.5 12.6 3.1 17.8 0.0625～0.2 Wacke 65.6 10.9 2.9 20.6 0.5～2 Subarkose 78.7 4.8 3.5 13.0 0.25～0.5

[0057] As mentioned above, it is not a restriction on the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, may make some changes or modifications to equivalent embodiments with equivalent changes by using the technical content disclosed above. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a complex structural geological model based on lithofacies distribution, characterized in that, it includes the following preparation steps: S1. Establish a three-dimensional bedding model based on seismic and stratigraphic data, and determine the model basement, target layer, and top layer; S2. Establish a three-dimensional lithofacies model using core and logging data, and determine the lithofacies types, top and bottom heights, and boundaries of each layer; S3. According to the similarity principle, scale the size of the three-dimensional lithofacies model proportionally to the test conditions, and use 3D printing technology to obtain each layer and lithofacies boundaries, and prepare a formation mold containing lithofacies distribution; S4. Conduct downhole core component analysis and particle size analysis of different lithofacies, obtain different lithofacies component information, the content of each component, and particle size distribution, and determine the casting material, its components, and particle size distribution; S5. Cast and form layer by layer from bottom to top; The implementation method of the step S1 is: Pour the layer space coordinate data into geological modeling software, plan the research scope of the target block, and perform regular cutting. Interpolate the layer data to obtain bedding data, and use the stratigraphic data to adjust the local structural position of the bedding. Finally, project the bedding longitudinally onto a plane to construct a three-dimensional structural model including the top and bottom layers; The implementation method of the step S2 is: S2.1 Divide the lithofacies types in the study area according to the rock combination characteristics and logging data and in combination with the regional sedimentary tectonic background, and convert a series of lithofacies types into codes; S2.2 Use logging data to identify lithofacies, construct a principal component equation related to lithofacies, and use an artificial intelligence algorithm to predict the lithofacies types of a single well and construct a single-well lithofacies distribution model; S2.3 Use the interpolation method to perform spatial interpolation on the single-well lithofacies prediction results, establish a three-dimensional structural model based on lithofacies distribution, and determine the lithofacies boundary and thickness of each layer.

2. The method for preparing a complex structural geological model based on lithofacies distribution according to claim 1, characterized in that, the implementation method of the step S4 is: Collect downhole rock samples of different lithofacies on site, and analyze the mineral components, mineral contents, and particle size distribution ranges of different types of rock particles through XRD tests and cast thin section analyses.

3. The method for preparing a complex structural geological model based on lithofacies distribution according to claim 1, characterized in that, the specific implementation method of the step S5 is: S5.1 Determine the casting raw materials according to the mineral component contents and particle size distributions of different lithofacies obtained in step S4; S5.2 Mix the mineral particles of different lithofacies according to the mineral types and contents to obtain mixtures of different lithofacies; S5.3 Put the mixture into the test box to simulate the base rock layer, then place the printed third-layer formation mold on the base rock layer, and pour the mixed material into the formation mold according to the lithofacies, controlling the filling amount slightly higher than the mold thickness; S5.4 Place the second-layer formation mold and apply pressure until the material is completely compacted, cemented, and consolidated; S5.5 Let it stand at room temperature and then demold; S5.6 Repeat steps S5.3 to S5.5 until the artificially prepared formation in the mold is gradually compacted and lithified layer by layer, and place it under certain temperature and natural drying conditions for curing until it is completely dry, and the preparation is completed to obtain a complex structural geological model based on lithofacies distribution.

4. The method for preparing a complex structural geological model based on lithofacies distribution according to claim 3, characterized in that, the pressure applied in step S5.4 is the vertical stress applied by the overlying rock formation.

5. The method for preparing a complex structural geological model based on lithofacies distribution according to claim 3, characterized in that, the standing time in step S5.5 is 2 h.

6. The method for preparing a complex structural geological model based on lithofacies distribution according to claim 3, characterized in that, the curing time in step S5.6 is 7 d, and the curing temperature is 10 - 30 °C.

7. The method for preparing a complex structural geological model based on lithofacies distribution according to claim 3, characterized in that, the curing temperature in step S5.6 is 20 °C.

8. A geological model prepared by the preparation method according to any one of claims 1 - 7.

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