A method for constructing an envelope surface based on a geological prototype model

Abstract

The present invention discloses a method for constructing an envelope surface based on a geological prototype model, and the specific steps are as follows: by analyzing the geometric characteristic parameters of different sedimentary types and different levels of configuration units, the main characteristic parameters are selected, and the geological prototype model is constructed using a modeling algorithm. On the basis of the establishment of the geological prototype model, the distribution range of the plane envelope surface of the configuration unit is drawn by combining well seismic data, and then a three-dimensional envelope surface is generated under the constraints of the geological prototype model. Finally, the boundary of the three-dimensional envelope surface is modified in combination with the well point configuration interpretation and geological knowledge to obtain the final three-dimensional envelope surface. The method for constructing an envelope surface based on a geological prototype model provided by the present invention is based on sparse spatial discrete data, and directly reconstructs the three-dimensional form of each level of configuration units in the form of an envelope surface under the constraints of the geological prototype model, so that the model is more in line with the real form of the geological body, and solves the industry problem of three-dimensional spatial representation of small-scale interfaces in reservoir configuration research.

Description

Technical Field

[0001] The invention relates to an envelope surface construction method based on a geological prototype model. Background Art

[0002] As more and more oil fields enter the high water content development stage, the requirements for quantitative characterization of reservoirs are getting higher and higher. How to characterize the small-scale configuration interface between reservoir configuration units at all levels, which has an important impact on fluid seepage, into the model is a current research difficulty. At present, conventional modeling methods, whether random modeling or deterministic modeling, are based on grids to perform three-dimensional characterization of geological bodies. Since the grid size cannot be set too small, some fine geological knowledge will inevitably be lost in the geological model. There are two shortcomings in using this modeling method. First, it is difficult to characterize small-scale geological bodies and their interfaces. Second, it cannot accurately characterize the geometric morphology of sand bodies and their overlapping and cutting relationships. If these geological information cannot be accurately characterized in the geological model, it cannot accurately reflect the small-scale seepage barriers, thereby reducing the distribution prediction accuracy of the remaining oil, and at the same time affecting the development effect.

[0003] Therefore, it is necessary to find a new method for quantitative characterization of reservoir architecture units to provide technical support for the precise prediction of remaining oil distribution. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention proposes an envelope surface construction method based on a geological prototype model to solve the problem that the conventional modeling method in the prior art cannot accurately reflect the small-scale seepage barriers and the prediction accuracy of the remaining oil distribution is not high.

[0005] The technical solution of the present invention is as follows: a method for constructing an envelope surface based on a geological prototype model, and the specific steps are as follows: a step of establishing a geological prototype model: by analyzing the geometric characteristic parameters of different sedimentary types and different order configuration units, the main characteristic parameters such as length, width, thickness, etc. are optimized, and the prototype model is constructed using a modeling algorithm.

[0006] On the basis of the establishment of the geological prototype model, the steps of constructing the envelope surfaces of various levels of configuration units under the constraints of the geological prototype model are carried out: first, the distribution range of the plane envelope surface of the configuration unit is drawn by combining well and seismic data; then, the initial three-dimensional envelope surface is generated under the constraints of the geological prototype model; finally, the boundary of the three-dimensional envelope surface is modified in combination with the well point configuration interpretation and geological understanding to obtain the final three-dimensional envelope surface.

[0007] The envelope surface construction method based on the geological prototype model provided by the present invention is based on sparse spatial discrete data, and directly reconstructs the three-dimensional shape of each level of configuration units in the form of an envelope surface under the constraints of the geological prototype model, so that the model is more consistent with the actual shape of the geological body, and solves the industry problem of three-dimensional spatial representation of small-scale interfaces in reservoir configuration research. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A flow chart of a method for constructing an envelope surface based on a geological prototype model provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0009] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0010] The core of the envelope construction method based on the geological prototype model is the establishment of the geological prototype model and the construction of the envelope of each level of configuration unit under its constraints. The specific implementation method is:

[0011] 1. Based on field outcrops, modern sediments and actual oilfield data, a geological knowledge base of corresponding sedimentary types and corresponding architectural levels is established. On this basis, the characteristic parameters of each architectural unit are analyzed, the main parameters are selected as input data, and the prototype model is established using the modeling algorithm.

[0012] 2. Draw the distribution range of the plane envelope of the configuration unit by combining well and seismic data, and then generate the initial three-dimensional envelope under the constraints of the geological prototype model. When drawing the envelope, the higher-order configuration units should be drawn first, and then the lower-order configuration units inside them should be drawn. For example, for braided river deposits, the distribution range of a single braided flow belt should be drawn first, and then the distribution range of a single heart bar should be drawn inside it, and finally the siltation layer should be drawn inside the single heart bar.

[0013] 3. The initial three-dimensional envelope surface is modified in combination with the well point configuration interpretation and geological understanding to obtain the final three-dimensional envelope surface of each level of configuration unit.

[0014] The establishment of the prototype model in the first step, due to the complexity and changeability of various geological depositional environments, the geological prototype modes are different, so it is necessary to establish a geological prototype model template library to organize and manage various depositional types and depositional modes of various configuration units. In addition, since the characteristic parameters of the same configuration unit are different in different regions and different oil fields, it is necessary to modify and set the characteristic parameters of the configuration unit in the process of applying the geological prototype model template library.

[0015] For meandering river deposits, the main structural units include single meander belt, terminal channel, abandoned channel, point bar, lateral accumulation body and lateral accumulation interlayer, among which the terminal channel and lateral accumulation interlayer are the key points of characterization.

[0016] For the final river channel, the steps for establishing the prototype model are as follows:

[0017] (1) Use the centerline control points and B-spline curve principle to form the riverbed centerline;

[0018] (2) Generate riverbank control points based on the normal direction of the centerline control point and the river width;

[0019] (3) Generate river bottom control points by combining the centerline control points with the river depth;

[0020] (4) Use the curvature of the centerline control point to correct the bottom control point of the convex bank riverbed;

[0021] (5) Use the river boundary control points to adjust the local shape of the river.

[0022] For the lateral accumulation interlayer, the steps for establishing the prototype model are as follows:

[0023] (1) Complete the plane drawing of the boundary distribution of the 5-level sand body;

[0024] (2) The model is constructed by combining the characteristic parameters of the lateral accumulation interlayer, such as the inclination, dip angle and extension length, with the thickness distribution of the sand body;

[0025] (3) The plane and cross-section shapes of the lateral accumulation interlayer are adjusted using the control points of the lateral accumulation interlayer, and the three-dimensional spatial configuration model of the lateral accumulation interlayer is updated synchronously.

[0026] For braided river deposits, the main structural units include single braided stream belt, braided channel, mid-shoal, aggradational body and silt interlayer, among which braided channel, mid-shoal and silt interlayer are the key points of characterization.

[0027] For braided channels and mid-bars, the steps for establishing the prototype model are as follows:

[0028] (1) Based on the characteristic parameters of the mid-channel bar, i.e., the major axis length, minor axis length, and thickness, the model characteristics are constructed using a modeling algorithm;

[0029] (2) The spatial location without a mid-channel bar in a single braided stream belt is the braided channel configuration unit envelope.

[0030] For the siltation interlayer, the steps for establishing the prototype model are as follows:

[0031] (1) According to the distribution morphology of the mid-shoal, the major axis length, minor axis length, distribution density or number of silt layers are set;

[0032] (2) Using the surface modeling algorithm, the configuration unit is constructed through the characteristic parameters of the silt layer configuration.

[0033] The generation of the initial three-dimensional envelope surface in step 2 is mainly based on actual oil field data and the constraints of the prototype model in step 1.

[0034] For meandering river deposits, the steps for generating the initial three-dimensional envelope surface are as follows:

[0035] (1) Draw the top structural map and thickness map of the sand body of the five-level structural unit of the target layer to constrain the three-dimensional spatial distribution position of the envelope surface;

[0036] (2) Draw the boundary of a single channel in the plane window based on the sand body distribution, seismic reflection information, and single well phase information;

[0037] (3) After the single river channel is drawn, the characteristic parameters of the final river channel, namely the river channel width and the river channel depth, are set in the meandering river prototype model template library, and then the final river channel is drawn in the plane window; the abandoned river channel is drawn in the same way as the final river channel;

[0038] (4) In the meandering river prototype model template library, set the characteristic parameters of the lateral accumulation interlayer, and then draw the lateral accumulation interlayer in the plane window.

[0039] For braided river deposits, the steps to generate the initial 3D envelope surface are as follows:

[0040] (1) Draw the top structural map and thickness map of the sand body of the five-level structural unit of the target layer to constrain the three-dimensional spatial distribution position of the envelope surface;

[0041] (2) In the braided river prototype model template library, specify the top surface of the configuration and the sand body thickness map for a single braided flow belt, and then draw a single braided flow belt along the sand body boundary in the plane window;

[0042] (3) Draw a single center-shoal boundary in the plane window based on sand body distribution, seismic reflection information, and single well phase information;

[0043] (4) In the braided river prototype model template library, the characteristic parameters of the siltation interlayer are set, and then the siltation interlayer is drawn.

[0044] In the third step, the initial three-dimensional envelope surface is modified to obtain the final three-dimensional envelope surface of each level of configuration unit, which is mainly carried out in the profile window. Due to the complexity of the underground geological body, the three-dimensional envelope surface is generated entirely based on the geological prototype model. There may be errors in some complex well areas. Therefore, it is necessary to verify and modify the initial three-dimensional envelope surface on the basis of the generation of the initial three-dimensional envelope surface. The specific steps are: generate vertical slices of the well and the configuration unit through a plane polygon, display the slices and the configuration unit in the geological section, and edit the morphology and combination relationship of the configuration unit in the geological section.

[0045] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for constructing an envelope surface based on a geological prototype model, characterized in that: The specific steps are as follows: (1) Steps for establishing the geological prototype model: By analyzing the geometric characteristic parameters of different sedimentary types and different order configuration units, the main characteristic parameters of length, width and thickness are obtained, and the prototype model is constructed using the modeling algorithm; (2) On the basis of the geological prototype model, the steps of constructing the envelope surface of each level of configuration unit under the constraint of the geological prototype model are as follows: first, the distribution range of the plane envelope surface of the configuration unit is drawn by combining well and seismic data; then, the initial three-dimensional envelope surface is generated under the constraint of the geological prototype model; (3) Finally, the boundary of the initial three-dimensional envelope surface is modified in combination with the well point configuration interpretation and geological knowledge to obtain the final three-dimensional envelope surface; In step (1), the geological prototype model is established. For meandering river deposits, the late river channel and lateral accumulation interlayer structure units are the key points of characterization: The steps for establishing the final river channel prototype model are as follows: 1-1 Use the centerline control points and B-spline curve principle to form the riverbed centerline; 1-2 Generate riverbank control points based on the normal direction of the centerline control point and the river width; 1-3 Generate river bottom control points by combining the center line control points with the river depth; 1-4 Use the curvature of the centerline control point to correct the bottom control point of the convex bank riverbed; 1-5 Use the river boundary control points to adjust the local shape of the river; The steps for establishing the lateral accumulation sandwich prototype model are as follows: 1-6 Complete the plane drawing of the boundary distribution of level 5 sand bodies; 1-7 The model is constructed by combining the characteristic parameters of the lateral accumulation interlayer, such as the inclination, dip angle and extension length, with the thickness distribution of the sand body; 1-8 Use the control points of the lateral accumulation interlayer to adjust its plane and section shapes, and simultaneously update the shape of the three-dimensional spatial configuration model of the lateral accumulation interlayer; The step (1) of establishing a geological prototype model focuses on the braided river sediments, with the braided river channel, mid-bar and siltation interlayer configuration units being the key points of characterization: The steps for establishing the prototype model of braided river channel and mid-shoal are as follows: 1-9 Based on the characteristic parameters of the mid-channel bar, i.e., the major axis length, the minor axis length and the thickness of the mid-channel bar, the model characteristics are constructed using a modeling algorithm; 1-10 The spatial location without mid-channel bar in a single braided stream belt is the braided channel configuration unit envelope; The steps for establishing the prototype model of the siltation sandwich are as follows: 1-11 According to the distribution form of the mid-shoal, set the major axis length, minor axis length, distribution density or number of silt layers; 1-12 Using the surface modeling algorithm, the configuration unit is constructed through the characteristic parameters of the silt layer configuration; The steps of generating the initial three-dimensional envelope surface in step (2) for meandering river deposition are as follows: 2-1 Draw the top surface structure map and thickness map of the sand body of the five-level configuration unit of the target layer to constrain the three-dimensional spatial distribution position of the envelope surface; 2-2 Draw a single river channel boundary in the plane window based on sand body distribution, seismic reflection information, and single well phase information; 2-3 After a single river channel is drawn, set the characteristic parameters of the final river channel, the width and depth of the river channel in the meandering river prototype model template library, and then draw the final river channel in the plane window; the drawing method of the abandoned river channel is the same as that of the final river channel; 2-4 In the meandering river prototype model template library, set the characteristic parameters of the lateral accumulation interlayer, and then draw the lateral accumulation interlayer in the plane window; The steps of generating the initial three-dimensional envelope surface in step (2) for braided river deposition are as follows: 2-5 Draw the top surface structure map and thickness map of the sand body of the five-level configuration unit of the target layer segment to constrain the three-dimensional spatial distribution position of the envelope surface; 2-6 In the braided river prototype model template library, specify the top surface of the configuration and the sand body thickness map for a single braided flow belt, and then draw a single braided flow belt along the sand body boundary in the plane window; 2-7 Draw a single center-shoal boundary in the plane window based on sand body distribution, seismic reflection information, and single well phase information; 2-8 In the braided river prototype model template library, set the characteristic parameters of the siltation interlayer, and then draw the siltation interlayer; The step (3) of modifying the boundary of the initial three-dimensional envelope surface is specifically as follows: generating vertical slices of the wells and the configuration units through the plane polygon, displaying the slices and the configuration units in the geological section, and editing the morphology and combination relationship of the configuration units in the geological section.

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