A method for generating geological models by random combination of multiple connected bodies in oil reservoirs

Abstract

The present invention belongs to the technical field of oil and gas field development engineering, and relates to a method for generating a geological model by randomly combining multiple connected bodies in an oil reservoir. The method of the present invention comprises the following steps: using oil reservoir geological model building software, identifying the boundaries of single connected bodies by calibrating the geological parameters of each single connected body, obtaining the morphology of each single connected body and characterizing it, randomly selecting grids where different single connected bodies are located and their geological parameters, and establishing a geological model of multiple connected body combinations by combining single connected bodies. The method of the present invention lays an important foundation for studying reservoir characteristics under different reservoir connected body connection modes.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development engineering, and relates to a method for generating a geological model by randomly combining multiple connected bodies of an oil reservoir. Background Art

[0002] my country has abundant reserves of sandstone and conglomerate oil reservoirs, which are characterized by great burial depth, rapid changes in vertical parameters, great difficulty in development, complex connectivity, and strong heterogeneity. Conglomerate reservoirs are different from conventional sandstone reservoirs. Conventional sandstone reservoirs are formed through long-term transportation and deposition. They are generally formed by single-stage deposition and have high composition and structural maturity. The sand bodies have clear boundaries and interlayers above and below. This type of reservoir is called a "sand body". However, the sedimentation time of conglomerate reservoirs is relatively short. They are generally formed by rapid deposition near the source. The reservoirs formed have complex components and low maturity. Since the reservoirs are rapidly accumulated by sandstone, conglomerate and mudstone, only areas with a high proportion of sandstone can become effective reservoirs. Therefore, conglomerate reservoirs have no obvious boundaries and strong heterogeneity on the plane. Therefore, the effective reservoirs of conglomerate are called "connected bodies".

[0003] In order to study the reservoir characteristics under different reservoir connected body distribution conditions, it is necessary to establish different multi-connected body models. At present, the establishment of multi-connected bodies mainly uses the determination method. By determining the deposition direction and deposition volume of each single connected body, multiple single connected bodies are combined into a single connected body model, and then the reservoir characteristics of each multi-connected body model are analyzed.

[0004] The random generation method of multi-connected bodies has its unique characteristics and can quickly generate a large number of different multi-connected body models, which is helpful for quickly analyzing reservoir characteristics under different connectivity patterns of reservoir connected bodies. Currently, there is no random generation method for connectivity patterns of reservoir connected bodies. Summary of the invention

[0005] The purpose of the present invention is to provide a method for generating a geological model by randomly combining multiple reservoir connected bodies, which is used to study reservoir characteristics under different reservoir connected body connection modes and fills the gap in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for generating a geological model by randomly combining multiple connected bodies in an oil reservoir, comprising the following steps: using oil reservoir geological model building software, identifying the boundaries of single connected bodies by calibrating the geological parameters of each single connected body, obtaining the morphology of each single connected body and characterizing it, randomly selecting grids where different single connected bodies are located and their geological parameters, and establishing a geological model of a combination of multiple connected bodies by combining single connected bodies.

[0008] Furthermore, the single connected body identification method comprises the following steps:

[0009] Obtain porosity field map and permeability field map;

[0010] The boundary of a single connected body is demarcated. According to the porosity field map and permeability field map in the geological model, the porosity greater than 5% and the permeability greater than 5×10 -3 μm 2 The reservoir is defined as the connected body boundary, which is used to distinguish the connected body from other parts and obtain the morphology of each single connected body.

[0011] Furthermore, the single connected body feature characterization method comprises the following steps:

[0012] Randomly select the single connected body to be analyzed;

[0013] Calculate the length of a single connected body along the source direction, the length perpendicular to the source direction and the distribution density of the connected body, and output statistical charts;

[0014] Accumulate the analysis results of the next image and perform cumulative calculations on multiple images.

[0015] Furthermore, the connected body distribution density is:

[0016]

[0017] In the formula, S D is the connected body distribution density; S H is the thickness of the connected body; T h is the thickness of the oil layer; n is the total number of vertically connected bodies; subscript i represents the i-th connected body.

[0018] Furthermore, establishing a geological model of a multi-connected body combination through a combination of single connected bodies specifically includes: determining the number of grids of the multi-connected body model to be determined, the number of single connected bodies, and the value of the connected body distribution density; randomly selecting single connected body characteristic parameters, randomly determining the position and rotation angle of each single connected body, establishing a multi-connected body model, and calculating its connected body distribution density; and obtaining a multi-connected body model that meets the requirements through screening.

[0019] Furthermore, the number of grids includes plane grids and longitudinal grids.

[0020] Furthermore, the multi-connected body model whose connected body distribution density is less than 10% relative error between the multi-connected body distribution density to be determined is selected.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention utilizes image processing technology to realize image recognition of single connected bodies in oil reservoirs, quantitatively characterizes characteristic parameters of single connected bodies, and establishes a multi-connected body model through a random generation method. The method of the present invention lays an important foundation for studying reservoir characteristics under different reservoir connected body connectivity modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 A flow chart of a method for generating a geological model by randomly combining multiple connected bodies of an oil reservoir according to a specific embodiment of the present invention;

[0025] Figure 2 The single connected body image described in a specific embodiment of the present invention;

[0026] Figure 3 A length statistical diagram of a connected body along the source direction according to a specific embodiment of the present invention;

[0027] Figure 4 A statistical diagram of the length of a connected body in a direction perpendicular to the source of matter according to a specific embodiment of the present invention;

[0028] Figure 5 A distribution diagram of the density of connected bodies according to a specific embodiment of the present invention;

[0029] Figure 6 This is a permeability field diagram of a multi-connected body model according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0032] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0033] Example 1

[0034] like Figure 1 As shown, the method for generating a geological model by randomly combining multiple connected bodies of an oil reservoir comprises the following steps:

[0035] 1. Single connected body image recognition

[0036] The reservoir geological modeling software is used to read the reservoir geological model data to obtain the permeability field and porosity field of the reservoir. The threshold of the connected body is determined as porosity greater than 5% and permeability greater than 5×10 -3 μm 2 , separate the connected body from the rest. For the convenience of display, the grayscale values ​​of the voxels corresponding to the connected body part are all changed to 0 after the image is segmented, that is, Figure 1 The grayscale values ​​of the corresponding voxels in the rest of the parts are all changed to 1, that is, Figure 2 The white part of the

[0037] 2. Calculate the characteristic parameters of a single connected body

[0038] Read the single-connected body image obtained by the image automatic recognition program, define the analysis window, and select the single-connected body image of the part to be analyzed, such as Figure 2 shown.

[0039] The length of the analyzed single connected body along the source direction, the length perpendicular to the source direction and the connected body distribution density are calculated, as shown in Table 1. The length of the single connected body along the source direction, the length of the single connected body perpendicular to the source direction and the connected body distribution density are plotted, as shown in Figure 3-5 shown.

[0040] The connected body distribution density is:

[0041]

[0042] In the formula, S D is the connected body distribution density; S H is the thickness of the connected body; T h is the thickness of the oil layer; n is the total number of vertically connected bodies; subscript i represents the i-th connected body.

[0043] Table 1 Characteristic parameters of a single connected body

[0044]

[0045] 3. Establishment of multi-connected body model

[0046] The number of plane grids of the input multi-connected body model is 20, the number of vertical grids is 6, and the number of single-connected bodies is 20. Randomly select and import the single-connected body characteristic parameters, randomly determine the position and rotation angle of each single-connected body, and establish a multi-connected body model; through screening, a multi-connected body model that meets the requirements is obtained, such as Figure 6 shown.

[0047] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for randomly generating a connection pattern of a reservoir interconnected body, characterized in that: The following steps are involved: Using reservoir geological modeling software, the boundaries of single-connected bodies are identified by calibrating the geological parameters of each single-connected body, the morphology of each single-connected body is obtained and characterized, the grids where different single-connected bodies are located and their geological parameters are randomly selected, and the geological model of multi-connected body combination is established through the combination of single-connected bodies; The single connected body identification method comprises the following steps: Obtain porosity field map and permeability field map; The boundary of a single connected body is demarcated. According to the porosity field map and permeability field map in the geological model, the porosity greater than 5% and the permeability greater than 5×10 -3 μm 2 The reservoir is defined as the connected body boundary, the connected body is distinguished from other parts, and the morphology of each single connected body is obtained; The single connected body feature characterization method includes the following steps: Randomly select the single connected body to be analyzed; Calculate the length of a single connected body along the source direction, the length perpendicular to the source direction and the distribution density of the connected body, and output statistical charts; Accumulate the analysis results of the next image and perform cumulative calculations on multiple images; The connected body distribution density is: In the formula, S D is the connected body distribution density; S H is the thickness of the connected body; T h is the thickness of the oil layer; n is the total number of vertically connected bodies; subscript i represents the i-th connected body; The geological model of establishing a combination of multiple connected bodies through the combination of single connected bodies specifically includes: determining the number of grids, the number of single connected bodies, and the value of the connected body distribution density of the multi-connected body model to be determined; randomly selecting the characteristic parameters of the single connected bodies, randomly determining the position and rotation angle of each single connected body, establishing the multi-connected body model, and calculating its connected body distribution density; and obtaining the multi-connected body model that meets the requirements through screening.

2. The method for randomly generating a connection pattern of a reservoir interconnected body according to claim 1, characterized in that: The grid numbers include plane grids and longitudinal grids.

3. The method for randomly generating a connection pattern of a reservoir interconnected body according to claim 1, characterized in that: The multi-connected body models whose connected body distribution density is generated by screening and whose numerical relative error between the multi-connected body distribution density to be determined is less than 10%.

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