Delta front interlayer three-dimensional quantitative characterization method
By combining seismic impedance inversion and the sequential indicator simulation algorithm of Petrel software with three-dimensional configuration modeling of underwater distributary channels, the uncertainty problem of three-dimensional modeling of delta front interlayers was solved, and the accurate characterization of the three-dimensional distribution law of interlayers was achieved, providing a reliable basis for fine tapping of remaining oil in high water-cut oilfields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2026-01-23
- Publication Date
- 2026-05-05
AI Technical Summary
Existing technologies do not use the three-dimensional configuration of underwater distributary channels as a constraint in the three-dimensional modeling of delta front interlayers, resulting in large uncertainties in the three-dimensional distribution of the interlayers and failing to meet the needs of fine tapping the remaining oil potential in high water-cut oilfields.
Seismic impedance inversion technology was used to obtain the planar distribution characteristics of a single sand body. A three-dimensional model of sandstone and mudstone lithofacies was established by combining the sequential indicator simulation algorithm of Petrel software. A three-dimensional distribution model of interlayers was constructed by modeling the three-dimensional configuration of underwater distributary channels and setting long and short ranges for random simulation.
The three-dimensional distribution pattern of the interlayer was accurately clarified, providing a reliable basis for the simulation and prediction of remaining oil in high water-cut oilfields, reducing development costs, and achieving the necessary conditions for efficient development.
Smart Images
Figure CN121978773A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of quantitative characterization technology, and in particular to a three-dimensional quantitative characterization method for delta front interlayers. Background Technology
[0002] Interlayers refer to thin, non-permeable or low-permeability lithological units within a reservoir, typically sandwiched between effective reservoir layers (such as sandstone), and significantly influence the flow of fluids such as oil and water within the reservoir. After decades of water injection development, oilfields are generally in a high-water-cut state within the reservoir. However, the presence of interlayers within the layers creates complex seepage structures. During water injection development, relatively rich areas of residual oil tend to form at the locations of interlayer development. Therefore, accurately characterizing the three-dimensional distribution of interlayers within the layers is an important prerequisite for conducting residual oil simulation, prediction, and full potential tapping in high-water-cut oilfields.
[0003] Different sedimentary environments result in different distribution patterns and morphologies of interlayers. In meandering river sand bodies, the shoal sand bodies developed on the convex bank are the main reservoir units. These sand bodies are formed by multiple sets of superimposed sand bodies migrating laterally from the convex bank of the meandering river, with muddy interlayers developing at an angle between these superimposed sand bodies. Delta front sand bodies are divided into distal sands, the frontal sand body, and underwater distributary channels. The distal sands and frontal sand bodies are relatively thin and do not have interlayers within them, while the underwater distributary channel sand bodies are thicker and have well-developed interlayers. Therefore, interlayers in delta front sand bodies are mostly developed within underwater distributary channels, and their morphology is controlled by the extent and length of the underwater distributary channels.
[0004] Interlayer geological modeling is a major technical means for three-dimensional quantitative characterization. Currently, there is considerable research on interlayer modeling in meandering rivers, and the technology is relatively mature. For example, the team led by Wu Shenghe at China University of Petroleum developed software for modeling interlayers in meandering rivers. However, the three-dimensional modeling technology for interlayers in delta front facies zones is still immature. The current main method is to directly conduct random simulations based on wellpoint interlayer identification, which increases the uncertainty of interlayer distribution and affects the reliability of subsequent residual oil simulation.
[0005] Therefore, it is necessary to propose a modeling method for delta front interlayers to reduce the uncertainty of three-dimensional quantitative characterization of the interlayers. Summary of the Invention
[0006] The purpose of this invention is to provide a three-dimensional quantitative characterization method for delta front interlayers, aiming to solve the problem that existing interlayer models do not take the three-dimensional configuration of the underwater distributary channel as a constraint, resulting in large uncertainty in the three-dimensional distribution and failing to meet the needs of fine tapping the remaining oil potential in high water-cut oilfields.
[0007] To achieve the above objectives, the present invention provides a three-dimensional quantitative characterization method for delta front interlayers, comprising the following steps: The planar distribution characteristics of a single sand body were obtained using seismic impedance inversion technology. Using the planar distribution characteristics of single sand bodies as planar trend constraints, a three-dimensional model of sandstone and mudstone lithofacies was established in Petrel using the sequential indicator simulation algorithm. Three-dimensional configuration modeling of underwater distributary channels was performed to obtain the configuration model; Within the configuration model, a long range is set along the river channel and a short range is set perpendicular to the river channel to conduct random simulations and obtain a three-dimensional distribution model of the interlayer.
[0008] The step of "3D configuration modeling of underwater distributary channels to obtain the configuration model" includes the following steps: Generate a structural diagram of the top surface of a single sand body in a sandstone-mudstone lithofacies model; Generate a single sand body thickness map; Set a sandstone thickness threshold; The thickness outside the boundary is set to zero and smoothed to generate an isopyrograph of sandstone in the underwater distributary channel. Subtracting the top surface structure diagram from the isothight diagram yields the bottom surface structure diagram of the underwater distributary channel; Using Petrel's "Assign between surface" function, the mesh between the top and bottom surfaces is assigned the underwater distributary channel facies code to establish a three-dimensional configuration model with a flat top and convex bottom.
[0009] In the setting of "Setting sandstone thickness threshold", the thickness threshold is 2.6m.
[0010] In the section "Three-dimensional configuration modeling of underwater diversion channels to obtain configuration model", the configuration model is used for prediction of the distribution of remaining oil in high water-cut oilfields.
[0011] This invention is a three-dimensional quantitative characterization method for delta front interlayers. It solves the problem of large uncertainty in the interlayer models built by existing methods, and establishes a unique hierarchical constraint modeling method. It accurately clarifies the three-dimensional distribution law of interlayers within the layer, provides a reliable basis for the simulation and prediction of remaining oil in high water-cut oilfields, and is a necessary prerequisite for the later-stage potential tapping, efficiency improvement, cost reduction and profitable development of oilfields. Attached Figure Description
[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, similar three-dimensional quantitative characterization results of delta front interlayers can be obtained by the method of the present invention without creative effort.
[0013] Figure 1 This is a flowchart of a three-dimensional quantitative characterization method for delta front interlayers provided by the present invention.
[0014] Figure 2 This is a plan view predicting the thickness of three small sandstone layers.
[0015] Figure 3 It is a three-dimensional planar diagram showing the distribution and thickness of the three sandstone layers.
[0016] Figure 4 This is a structural diagram of the top surface of a three-layered single sand body.
[0017] Figure 5 It is a map of sandstone of equal thickness in three sub-layer underwater distributary channel areas.
[0018] Figure 6 This is a diagram of the bottom structure of a three-layered underwater diversion channel.
[0019] Figure 7 This is a diagram of a three-layer underwater diversion channel configuration.
[0020] Figure 8 This is a diagram analyzing the main variable range of the three small-layer interlayer.
[0021] Figure 9 This is a three-dimensional distribution model diagram of three small interlayers. Detailed Implementation
[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar geological bodies or geological bodies having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0023] Please see Figures 1 to 9 This invention provides a three-dimensional quantitative characterization method for delta front interlayers, comprising the following steps: S1 uses seismic impedance inversion technology to obtain the planar distribution characteristics of a single sand body; Specifically, the mature seismic impedance inversion technique in Jason software was used to predict the planar distribution characteristics of a single sand body, and attached... Figure 2 This is a plan view showing the predicted thickness of three sandstone layers in area A.
[0024] S2 uses the planar distribution characteristics of single sand bodies as planar trend constraints and employs a sequential indicator simulation algorithm in Petrel to establish a three-dimensional model of sandstone and mudstone lithofacies. Specifically, based on the structural modeling, the planar distribution characteristic map of the single sand body obtained in step 1 is used as a trend constraint for the distribution characteristics of sandstone in the three-dimensional simulation of lithofacies. The sequential indicator simulation algorithm in Petrel is then applied to conduct stochastic modeling of sandstone and mudstone lithofacies. (See attached...) Figure 3It can be seen that the three-dimensional distribution and thickness plan of the sandstone in the three sub-layers are generally similar to the results of the seismic reservoir prediction. By using lithological seismic control modeling, the uncertainty of the sandstone distribution range and thickness variation characteristics in the model has been reduced.
[0025] Three-dimensional configuration modeling of the S3 underwater distributary channel was performed to obtain the configuration model; The configuration model is used to predict the distribution of remaining oil in high water-cut oilfields.
[0026] S31 generates a structural diagram of the top surface of a single sand body in a sandstone-mudstone lithofacies model; Specifically, based on the sandstone and mudstone lithofacies model generated in step S2, in the model's Settings, apply the "Operations---Make reservoir top map" function in Petrel to calculate the structural map of the top surface of the single sand body in the three sub-layers of the model (attached). Figure 4 ).
[0027] S32 generates a single sand body thickness map; Specifically, based on the sandstone and mudstone lithofacies model generated in step S32, in the model's Settings, apply the "Operations---Make thickness map" function in Petrel to calculate the thickness maps of individual sand bodies in the three sub-layers of the model (see attached). Figure 3 ).
[0028] S33 sets the sandstone thickness threshold; The thickness threshold is 2.6m.
[0029] Specifically, the single sand body thickness map generated in step S32 is analyzed. Based on the "tree-like" distribution pattern of the underwater distributary channels of single sand bodies on the plane (such as the underwater distributary channels of Poyang Lake delta advancing into the lake in a "tree-like" pattern) and the general rule that the sandstone thickness of the channel is more than 2.6m, combined with the distribution characteristics of the single sand body thickness map, the area with a sandstone thickness greater than 2.6m is regarded as the underwater distributary channel, and the closed line of the boundary of the lower distributary channel is drawn.
[0030] S34 sets the thickness outside the boundary to zero and smooths it to generate an isopyrograph of sandstone in the underwater distributary channel. Specifically, using the underwater distributary channel closure boundary line generated in step S33 as the calculation condition, the model calculator is applied to assign a thickness of 0 to the sandstone region outside the boundary line, and boundary smoothing is performed to generate a sandstone isopyrograph of the three sub-layers of the underwater distributary channel region (attached). Figure 5 ).
[0031] S35 obtains the underwater distributary channel bottom structure map by subtracting the top surface structure map from the isothight map; Specifically, by applying the top surface structure map of the single sand body generated in step S31 and the isopyrograph of the sandstone in the underwater distributary channel area generated in step ④, and subtracting the values from the two maps using a calculator, the bottom surface structure map of the three sub-layers of the underwater distributary channel is obtained (see attached map). Figure 6 ).
[0032] S36 uses Petrel's "Assign between surface" function to assign the mesh between the top and bottom surfaces to the underwater distributary channel facies code, thus establishing a three-dimensional configuration model with a flat top and convex bottom.
[0033] Specifically, using the "Assign between surface" function in Petrel, the spatial region between the top surface structure map of the single sand body generated in step S31 and the bottom surface structure map of the underwater distributary channel generated in step S35 is assigned the code of the underwater distributary channel facies. This allows the three-dimensional configuration of the three sub-layer underwater distributary channel—flat at the top and convex at the bottom—to be embedded into the single sand body model. (See attached image) Figure 7 ).
[0034] S4 uses a long range along the river channel and a short range perpendicular to the river channel within the configuration model to perform random simulations and obtain a three-dimensional distribution model of the interlayer.
[0035] Specifically, the delta front sand bodies are generally thin, with interlayers mostly developing within thick sand bodies of the underwater distributary channel facies. The distribution morphology of the underwater distributary channel facies sand bodies within these sand bodies determines the location and morphology of the interlayers. Based on the distribution pattern of interlayers in the delta front, facies-controlled stochastic simulations of interlayers were conducted. Three sub-layers of the underwater distributary channel facies were used as constraints, and the main range direction of the interlayers was set along the channel direction (nearly east). Analysis of the variogram of the surface interlayer data shows (see attached figure)... Figure 8 The distance corresponding to the "inflection point" or "plateau starting point" where the scatter plots change from a clear upward trend to a flattening and stabilizing trend is the magnitude of the main range, therefore the main range is determined to be 300m; the secondary range is perpendicular to the river channel direction, with an average river channel width of 150m. Based on the understanding that the extension range of the interlayer perpendicular to the river channel direction does not exceed the river channel width, the secondary range is set at 120m. (See Appendix) Figure 9 It can be seen that the interlayers of the three sub-layers are mainly distributed within the underwater distributary channel facies. Along the channel direction, the interlayers extend relatively long, while perpendicular to the channel direction, the interlayers extend relatively short. This conforms to the sedimentary rule described in the background and problem analysis above: "In deltaic front sedimentary environments, interlayers are mostly developed in thick sand bodies of the underwater distributary channel facies. The distribution range of the sand body and the distribution morphology of the underwater distributary channel facies sand body within the sand body determine the development location and morphology of the interlayers." Beneficial effects
[0036] This invention solves the problem of large uncertainty in the interlayer model constructed by existing methods, and establishes a unique hierarchical and step-by-step constraint modeling method, which accurately clarifies the three-dimensional distribution law of the interlayer within the layer, provides a reliable basis for the simulation and prediction of remaining oil in high water-cut oilfields, and is a necessary prerequisite for the later-stage potential tapping and efficiency improvement, reduction of development costs and realization of profitable development in oilfields.
[0037] The above-disclosed embodiments are merely preferred embodiments of a three-dimensional quantitative characterization method for delta front interlayers according to the present invention. Of course, they should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.
Claims
1. A three-dimensional quantitative characterization method for delta front interlayers, characterized in that, Includes the following steps: The planar distribution characteristics of a single sand body were obtained using seismic impedance inversion technology. Using the planar distribution characteristics of single sand bodies as planar trend constraints, a three-dimensional model of sandstone and mudstone lithofacies was established in Petrel using the sequential indicator simulation algorithm. Three-dimensional configuration modeling of underwater distributary channels was performed to obtain the configuration model; Within the configuration model, a long range is set along the river channel and a short range is set perpendicular to the river channel to conduct random simulations and obtain a three-dimensional distribution model of the interlayer.
2. The three-dimensional quantitative characterization method for delta front interlayers as described in claim 1, characterized in that, The steps in "3D configuration modeling of underwater distributary channels to obtain the configuration model" include: Generate a structural diagram of the top surface of a single sand body in a sandstone-mudstone lithofacies model; Generate a single sand body thickness map; Set a sandstone thickness threshold; The thickness outside the boundary is set to zero and smoothed to generate an isopyrograph of sandstone in the underwater distributary channel. Subtracting the top surface structure diagram from the isothight diagram yields the bottom surface structure diagram of the underwater distributary channel; Using Petrel's "Assign between surface" function, the mesh between the top and bottom surfaces is assigned the underwater distributary channel facies code to establish a three-dimensional configuration model with a flat top and convex bottom.
3. The three-dimensional quantitative characterization method for delta front interlayers as described in claim 2, characterized in that, In "Setting Sandstone Thickness Threshold", the thickness threshold is 2.6m.
4. The three-dimensional quantitative characterization method for delta front interlayers as described in claim 1, characterized in that, In "Three-dimensional configuration modeling of underwater distributary channels to obtain configuration model", the configuration model is used to predict the distribution of remaining oil in high water-cut oilfields.