Three-dimensional sedimentary evolution simulation method

Abstract

The invention discloses a three-dimensional sedimentary evolution simulation method. The method comprises the following steps: acquiring influence factors of a containing space, material source supply and sedimentary carrying in a target block stratum sedimentary process; establishing an initial three-dimensional sedimentary evolution model by utilizing the influence factors; correcting and optimizing the initial three-dimensional sedimentary evolution model through well drilling information of a posterior well to obtain a three-dimensional sedimentary evolution model of the target block; the problem that three-dimensional deposition evolution simulation of a multi-source deposition system and / or a low well control area is low in accuracy or large in prediction difficulty is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of geological exploration and development of oil and gas reservoirs, and in particular to a simulation method for sedimentary evolution processes in risky exploration areas with insufficient well control areas within a basin based on sequence stratigraphy, sedimentology, three-dimensional geological modeling and numerical simulation technology. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Numerical simulation of sedimentary evolution has important guiding significance for revealing basin evolution, sedimentary phase patterns, reservoir distribution prediction and well location deployment. It is an important research content of oil and gas basin analysis and a hot topic in sedimentary basin research at home and abroad in recent years. Through the study of basin sedimentary evolution process, the sedimentary evolution process of strata in geological history can be reproduced.

[0004] Conventional sedimentary system research methods rely on the degree of well control. In areas where the degree of well control is insufficient, the uncertainty is large and the accuracy is low. It is impossible to quantitatively describe the characteristics of the sedimentary system and accurately predict exploration targets. In addition, for multi-source sedimentary systems controlled by complex structures, conventional sedimentary system research methods are difficult to predict.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may contain information that does not constitute prior art. Summary of the invention

[0006] In view of this, the present disclosure provides a three-dimensional sedimentary evolution simulation method to solve the problem of low accuracy or great prediction difficulty in three-dimensional sedimentary evolution simulation in multi-source sedimentary systems and / or low well control areas.

[0007] To achieve the above-mentioned object of the invention, the three-dimensional sedimentary evolution simulation method comprises:

[0008] Obtain the factors affecting the accommodating space, material supply mode and sedimentation and transportation during the sedimentation process of the target area;

[0009] Establishing an initial three-dimensional sedimentary evolution model using the influencing factors;

[0010] The initial three-dimensional sedimentary evolution model is corrected and optimized by using the drilling information of the post-test well to obtain the three-dimensional sedimentary evolution model of the target block.

[0011] In the present disclosure and possible embodiments, factors affecting the accommodative space include the initial water depth of the base, water level changes and sedimentation; factors affecting the material supply include material supply mode, material supply amount and material supply rate; factors affecting the sedimentation transport include transport method and diffusion coefficient.

[0012] In the present disclosure and possible embodiments, the initial water depth of the substrate is determined using an initial water depth map of the substrate.

[0013] In the present disclosure and possible embodiments, the global water level rise and fall curve is used to extract the water level change of the target block.

[0014] In the present disclosure and possible embodiments, the material source supply mode includes material source position, material source direction, material source width and material source lithological composition; the material source position and the material source direction are the same as the distribution position and direction of sandstone on the sedimentary phase diagram; the material source width is determined according to the distribution of formation thickness; the material source lithological composition is determined according to the formation sand-to-formation ratio, and the sum of the percentages of all lithologies is 1.

[0015] In the present disclosure and possible embodiments, the source supply amount = formation thickness / target block range / total time.

[0016] In the present disclosure and possible embodiments, the supply volume and lithology ratio of each source inflow point are split according to the sedimentary phase distribution and vertical lithology combination revealed by drilling information, and the change of source supply rate over time is simulated by adjusting the source supply volume and lithology ratio.

[0017] In the present disclosure and possible embodiments, the diffusion coefficient is determined based on a diffusion equation;

[0018] The diffusion equation is:

[0019] Qs=S*K+S ns *Q nq *K

[0020] Where: Qs represents the sediment transport volume, S represents the slope, K represents the diffusion coefficient, Q represents the water flow, and the power exponent ns for modifying the slope and the power exponent nq for modifying the water flow can be defined.

[0021] In the present disclosure and possible embodiments, the initial three-dimensional sedimentation evolution model is established based on Dionisosflow.

[0022] The present disclosure has the following beneficial effects:

[0023] The method disclosed in the present invention is based on the source-sink concept, and by quantifying the main controlling factors of the sedimentary evolution process, comprehensively considering the combined effects of the change in the accommodating space, the supply of material sources and the transport mechanism, and by continuously iterating the model, numerically simulating the sedimentary evolution process of the stratum, it provides a scientific and relatively reliable research method for the sedimentary evolution process in the risk exploration field with insufficient well control areas in the basin, and obtains more objective and more practical sedimentary evolution laws through model iteration, thereby effectively guiding the exploration of oil and gas reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0025] Figure 1 This is a flow chart of the three-dimensional sedimentation evolution simulation method described in an embodiment of the present disclosure.

[0026] Figure 2 It is a schematic diagram of the definition of the regional work area of ​​the embodiment;

[0027] Figure 3 It is a definition map of lithology and other attributes of the embodiment area;

[0028] Figure 4 A geological time definition diagram for the start and end time of the regional model and the stratification boundaries of the embodiment;

[0029] Figure 5 It is a diagram of the change of water level during the deposition process in the example area;

[0030] Figure 6 For example, the regional settlement map;

[0031] Figure 7 It is a diagram of the material supply pattern of the embodiment area;

[0032] Figure 8 The graph of the supply rate of material resources in the example area over time;

[0033] Figure 9-1 The three-dimensional sedimentary evolution model of the example area (180.00Ma);

[0034] Figure 9-2 This is a three-dimensional sedimentary evolution model for the example area (179.50Ma);

[0035] Figure 9-3 The three-dimensional sedimentary evolution model of the example area (179.00Ma);

[0036] Figure 9-4 The three-dimensional sedimentary evolution model of the example area (178.50Ma);

[0037] Figure 9-5 The three-dimensional sedimentary evolution model of the example area (178.00Ma);

[0038] Figure 9-6 The three-dimensional sedimentary evolution model of the example area (177.50Ma);

[0039] Figure 9-7 The three-dimensional sedimentary evolution model of the example area (177.00Ma);

[0040] Figure 9-8 The three-dimensional sedimentary evolution model of the example area (176.50Ma);

[0041] Figure 9-9 The three-dimensional sedimentary evolution model of the example area (176.00Ma);

[0042] Figure 9-10 The three-dimensional sedimentary evolution model of the example area (175.50Ma);

[0043] Figure 9-11 This is the three-dimensional sedimentary evolution model of the example area (175.00Ma). DETAILED DESCRIPTION

[0044] The present disclosure is described below based on embodiments, but it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, some specific details are described in detail. However, for the parts that are not described in detail, those skilled in the art can also fully understand the present disclosure.

[0045] In addition, those skilled in the art should understand that the drawings are only provided to illustrate the purpose, features and advantages of the present disclosure, and the drawings are not actually drawn to scale.

[0046] At the same time, unless the context clearly requires otherwise, the words "include", "comprises" and similar words throughout the specification and claims should be interpreted as inclusive rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

[0047] Figure 1 The flowchart of the three-dimensional sedimentation evolution simulation method described in the embodiment of the present disclosure; Application Figure 1 The method shown in this paper numerically simulates the three-dimensional sedimentary evolution process of the Jurassic Lianggaoshan Formation in the Sichuan Basin. It is necessary to collect and analyze the seismic, well logging, core and regional sedimentary environment data of the Jurassic Lianggaoshan Formation in the Sichuan Basin in advance, comprehensively apply the three-dimensional seismic interpretation, well logging curve comparison and grain size analysis data, collect the research results of regional sedimentary environment, carry out basic data analysis in the study area, and extract digital maps and data representing sedimentary parameters.

[0048] Using the information and data collected and analyzed above, Dionisosflow is used to perform three-dimensional deposition simulation. The specific steps are as follows:

[0049] Step S1: Define the basic information of the simulation work area, including:

[0050] like Figure 2As shown, the simulation work area range is defined, including the work area origin coordinates X0 = 18296365m, Y0 = 3380703m, the work area inclination angle 50°, the work area length 490km and width 390km, the plane grid spacing DX = DY = 10000m, and all model graphics will be displayed based on this work area range;

[0051] like Figure 3 As shown, the lithology and other attributes are defined, including the color, particle size, density, porosity, etc. of the lithology and the selected lithology. The lithology simulated in this embodiment is a clastic rock deposit composed of sandstone and mudstone.

[0052] like Figure 4 As shown, the sedimentary evolution process is defined, including the start and end time of the model is 180.5 ~ 175Ma, with a total duration of 5.5Ma; the geological age of the stratification boundary (corresponding to how many Ma each layer).

[0053] Step S2: Determination of available space:

[0054] During the accumulation of strata in a sedimentary basin, the accommodating space is equal to the sum of the stratum thickness and the water depth, which is also equal to the sum of the relative horizontal plane and the sedimentation. Therefore, the factors affecting the accommodating space can be obtained from the following aspects:

[0055] Initial water depth of base: Import the initial water depth map of base to obtain the initial water depth of base.

[0056] Level change: Input the start and end time of the simulated work area, 180.5~175Ma, and use the built-in global level rise and fall curve provided by the software to extract the level change of the simulated work area, such as Figure 5 shown.

[0057] Sedimentation = H2-H1 ①

[0058] H1 = Water depth 1 (initial water depth of base)②

[0059] H2 = formation thickness + water depth 2 (both can be obtained from the formation thickness map) ③

[0060] From ①②③, we can conclude that:

[0061] H2-H1=stratum thickness+water depth 2-water depth 1 ④

[0062] Subsidence = stratum thickness + change in water depth⑤

[0063] When the change of water depth has little effect on the accommodation space, the thickness of the stratum roughly reflects the total settlement of the basement. The whole area is a delta-lake phase sedimentary system. The average change of lake level during the Lianggaoshan Formation deposition period does not exceed 10m, and the average thickness of the stratum is 200m. Therefore, the effect of water depth change on the accommodation space can be ignored, and the thickness of the stratum roughly reflects the total settlement of the basement. Figure 6 shown.

[0064] Step S3: Material supply simulation:

[0065] The factors affecting material supply include material supply mode, material supply quantity and material supply rate, among which:

[0066] Source supply mode: Figure 7 As shown, it includes four provenance supply parameters, namely, provenance position, provenance direction, provenance width and provenance lithology composition. The provenance position and direction are simulated from the regional sedimentary knowledge and the distribution position and direction of sandstone on the sedimentary phase diagram. The simulated provenance position and direction are the same as the distribution position and direction of sandstone on the sedimentary phase diagram; the provenance width is simulated according to the distribution of stratum thickness. The initial simulated provenance width should not be too large. A grid size is defined first, and then adjusted later according to the distribution of stratum thickness; the provenance lithology composition is determined according to the stratum sand-to-land ratio, and the percentages of all lithologies are added up to 1. The provenance position of this embodiment is at the location of the paleogeomorphic valley, the provenance direction is mainly in the west and northeast, the initial simulated provenance width is a grid size of 10,000 m, and the percentages of sandstone and mudstone in the lithology composition are 0.3 and 0.7, respectively.

[0067] Material supply: The total material supply is estimated by the formation thickness, total material supply = formation thickness / work area range / total duration (Ma). In this embodiment, the average formation thickness is 200m, the work area length is 490km and the width is 390km, and the total duration is 5.5Ma.

[0068] Source supply rate: Figure 8 As shown in the figure, according to the sedimentary facies distribution and vertical lithology combination revealed by drilling information, the supply volume and lithology ratio of each source inflow point are reasonably split, and the change of source supply rate over time is simulated by adjusting the source supply volume and lithology ratio.

[0069] Step S4: Deposition and transport simulation:

[0070] Sediment transport controls the local morphology of the sediment body and is determined by the transport mode and the diffusion coefficient, where:

[0071] The transportation methods are divided into long-term low-energy transportation and short-term high-energy transportation. Long-term low-energy transportation is used to describe river deltas. It can define the slope of continental and marine environments and the proportion of water flow transportation and gravity transportation in the long-term low-energy transportation system; short-term high-energy transportation is used to describe the morphology of delta fronts, lake bottom fans, and fan delta fan bodies. It can define the proportion of short-term high energy in the transportation process, and modify the flood interval and the proportion of water flow load in flood and dry seasons. The entire simulation process is set according to experience, and the parameters are continuously modified until the simulation is more than 90% consistent with the actual well. Based on the experience of delta and fan delta simulation, this embodiment is set to transport 30% of the total material sources in a long-term low-energy manner and 70% of the total material sources in a short-term high-energy manner.

[0072] The diffusion coefficient is determined by the particle size and slope. The larger the particle size carried by the water flow, the more difficult it is to transport it downstream. The greater the slope, the faster the sediment enters the lake area, the greater the total amount of sediment, and the easier it is to form a delta at the estuary.

[0073] Among them, the diffusion coefficient is mainly based on the diffusion equation:

[0074] Qs=S*K+S ns *Q nq *K

[0075] In the formula: Qs represents the sediment transport volume, S represents the slope, K represents the diffusion coefficient, and Q represents the water flow. The power exponent ns for modifying the slope and the power exponent nq for modifying the water flow can be defined.

[0076] Step S5: Set the step size to 0.5 Ma and establish an initial three-dimensional sedimentary evolution model.

[0077] Step S6: Model calibration and optimization:

[0078] After completing the initial three-dimensional sedimentary evolution model, the actual well data (drilling information of the a posteriori well) is imported for model evaluation and calibration. If the simulation results are significantly different from the actual results, the model is adjusted.

[0079] Step S7: Determine whether the consistency rate with the actual drilling is more than 90%. If not, repeat the above-mentioned material supply, sedimentation and transportation, establishment of a three-dimensional sedimentary evolution model, and model correction and optimization process until the final simulated thickness and lithology ratio are more than 90% consistent with the actual drilling.

[0080] Table 1 Simulation calibration data table

[0081] well Layer thickness / m Simulated thickness / m Error rate / % Ping An 1 164 172.2 -5％ Camp 1 138 138.8 -0.6％ Yingshan 102 173 172.8 0.1％ Longgang 167 116 105.8 8.8％ Longgang 28 130 132.6 -2％ Hechuan 3 57 54.9 3.6％ Hechuan 125 68 68.4 -0.6％ High Stone 105 27.5 27.1 1.4％ Nanchong 1 61.7 57.7 6.5％

[0082] As shown in Table 1, the simulated thickness after correction is highly consistent with the formation thickness divided by the well points, with the error not exceeding ±10%, and most of them controlled at around ±5%, indicating that the model is highly reliable.

[0083] Step S8: Output the three-dimensional sedimentary evolution model, such as Figure 9-1 to Figure 9-11 As shown, the program ends.

[0084] It can be seen from the technical solution of the present invention that this method is based on the source-sink concept. By quantifying the main controlling factors of the sedimentary evolution process, comprehensively considering the combined effects of the changes in the available space, the supply of material sources and the transportation mechanism, and continuously iterating the model, the stratigraphic sedimentary evolution process is numerically simulated, which provides a scientific and relatively reliable research method for the sedimentary evolution process in the risk exploration field with insufficient well control areas in the basin.

[0085] The above-described embodiments are only embodiments of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the present disclosure. It should be noted that, for a person of ordinary skill in the art, without departing from the concept of the present disclosure, several variations, equivalent substitutions, improvements, etc. may be made, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the attached claims.

Claims

1. A three-dimensional sedimentary evolution simulation method, characterized in that: include: Obtain the factors affecting the accommodating space, material supply mode and sedimentation and transportation during the sedimentation process of the target area; Establishing an initial three-dimensional sedimentary evolution model using the influencing factors; The initial three-dimensional sedimentary evolution model is corrected and optimized by using the drilling information of the post-test well to obtain the three-dimensional sedimentary evolution model of the target block.

2. The three-dimensional sedimentation evolution simulation method according to claim 1, characterized in that: Factors affecting the accommodating space include the initial water depth of the base, water level changes and sedimentation; factors affecting the material supply include material supply mode, material supply amount and material supply rate; factors affecting the sediment transport include transport method and diffusion coefficient.

3. The three-dimensional sedimentation evolution simulation method according to claim 2, characterized in that: The initial water depth of the base is determined using the base initial water depth map.

4. The three-dimensional sedimentation evolution simulation method according to claim 3, characterized in that: The global water level rise and fall curve is used to extract the water level change of the target block.

5. The three-dimensional sedimentation evolution simulation method according to claim 4, characterized in that: The material source supply mode includes material source position, material source direction, material source width and material source lithology composition; the material source position and the material source direction are the same as the distribution position and direction of sandstone on the sedimentary phase diagram; the material source width is determined according to the distribution of stratum thickness; The lithology of the source is determined based on the formation sand-to-formation ratio, and the sum of the percentages of all lithologies is 1.

6. The three-dimensional sedimentation evolution simulation method according to claim 5, characterized in that: The source supply amount = formation thickness / target block range / total time.

7. The three-dimensional sedimentation evolution simulation method according to claim 6, characterized in that: According to the sedimentary facies distribution and vertical lithology combination revealed by drilling information, the supply volume and lithology ratio of each provenance inflow point are split, and the change of provenance supply rate over time is simulated by adjusting the provenance supply volume and lithology ratio.

8. The three-dimensional sedimentation evolution simulation method according to claim 7, characterized in that: determining the diffusion coefficient based on a diffusion equation; The diffusion equation is: Qs=S*K+S ns *Q nq *K Where: Qs represents the sediment transport volume, S represents the slope, K represents the diffusion coefficient, Q represents the water flow, and the power exponent ns for modifying the slope and the power exponent nq for modifying the water flow can be defined.

9. The three-dimensional sedimentation evolution simulation method according to any one of claims 1 to 8, characterized in that: The initial three-dimensional sedimentary evolution model is established based on Dionisosflow.

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