CN111291497A - Improved digital core modeling method - Google Patents

Abstract

The invention discloses an improved digital core modeling method, comprising the following steps: A. acquiring rock particle characteristics; B. simulating rock particles; C. simulating deposition, compaction and diagenesis; D. building a digital core model. The application of EDEM in the invention can not only simulate the changes such as the translation, deformation, rotation, rearrangement and fragmentation of particles in the compaction, but also combine the simulation of the early sedimentation and the later diagenesis, so that the entire rock formation process can be visualized and can be used at any time. Monitoring and analysis of particle and pore changes. To ensure that the whole process method to construct digital core is more accurate.

Description

An Improved Digital Core Modeling Method

technical field

The invention relates to the field of geotechnical technology, in particular to an improved digital core modeling method.

Background technique

Digital core technology is an effective method for core analysis that has emerged in recent years. It has been widely used in earth science, geotechnical engineering and environmental engineering and has achieved great success. The basic principle is based on two-dimensional or three-dimensional core scanning images, using computer image processing technology, and completing digital core reconstruction through certain algorithms.

Cores are formed from natural rock particles through sedimentation, compaction and diagenesis. The process method is a technology for constructing digital cores by simulating the above rock formation process. Because the constraint condition of the process method is the rock particle information data obtained from rock slices or other methods, the modeling flexibility is stronger, and the simulation of the process method adds geological factors, and considers the formation process and anisotropy of the rock. The constructed digital core is more accurate. It has received extensive attention from scholars at home and abroad.

The formation of rocks in nature includes three stages of deposition, compaction and diagenesis, and the process is complex. Especially when compaction occurs, the rock particles are often subjected to the pressure of the rocks above and around them, the friction force generated by the water flow, the static pressure in the water and other friction forces, resulting in changes such as translation, deformation, rotation, rearrangement and even fragmentation of the particles. The original pores between the rock particles are greatly reduced. For example, compaction in tight sandstones can lead to loss of original porosity as high as about 60%. Because compaction exists throughout the rock diagenesis process, it has a huge impact on rock properties. When using the process method to simulate digital cores, the accurate simulation of compaction is particularly important.

In order to solve this problem, scholars at home and abroad have set up assumptions when simulating compaction. In the process of simulating compaction, Bakke and Φren (1997) assumed that the geometry of the particles did not change, there was no lateral displacement, the particles did not rotate, and the particles were inelastically deformed. compaction process. Zhu (2012) assumed that the particles only translate during the compaction process, and considered that the compaction of particles includes compaction in both vertical (Z-axis) and horizontal (X-axis, Y-axis) directions. simulation. Culler (2014) in order to achieve the effect of particle rearrangement and porosity reduction after compaction, the Z-axis coordinate of all sediment particles or spheres is reduced (moved down) to achieve, through the compaction factor ( Generally take [0,1]) and particle rearrangement factor (generally take [-0.02,0.02]) to control the degree of compaction and the state of particle arrangement.

To sum up, the predecessors simulated the compaction process through the translation of the particles under the assumption that the particles do not deform, rotate and break. In order to ensure the accuracy of digital cores, it is often necessary to change the compaction factor and particle rearrangement factor for multiple simulations to achieve satisfactory results. This attempt is slow, and the simulation results are too random, which greatly reduces the efficiency of digital core modeling.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an improved digital core modeling method to solve the problems raised in the above background art.

To achieve the above object, the present invention provides the following technical solutions:

An improved approach to digital core modeling comprising the following steps:

A. Obtain rock particle characteristics;

B. Simulated rock particles;

C. Sedimentation, compaction, and diagenesis simulation;

D. Build a digital core model.

As a further technical solution of the present invention: the step A is specifically: acquiring rock particle characteristics. The cores were selected for sample preparation, and the size, shape, composition and distribution characteristics of rock particles in the samples were obtained by casting thin sections, particle size analysis and CT scanning.

As a further technical solution of the present invention: the step B is carried out in two steps: 1. simulating the shape of real rock particles with 3D software; 2. importing the particle geometry simulated by the 3D software into EDEM with Creator, and adding particles Composition and size information, complete the establishment of particle model.

As a further technical solution of the present invention: during the deposition process of the step C, the rock particles will experience falling and rolling, and then enter the compaction stage after reaching the initial stable state, and the particles will undergo changes such as translation, deformation, rotation, rearrangement and fragmentation. , and then enter the diagenetic stage, the particles will undergo cementation, dissolution or autogenous increase, resulting in further changes in the shape of rock particles, and finally the formation of the current rock.

As a further technical solution of the present invention: in the step C, a Simulator is used to simulate a series of changes of particles in the process of deposition, compaction and diagenesis.

As a further technical solution of the present invention: the step D is specifically: after a series of rock formation processes are simulated, use Analyst to generate a digital core model.

As a further technical solution of the present invention: the three-dimensional software is CAD.

Compared with the prior art, the beneficial effects of the present invention are: the application of EDEM in the present invention can not only simulate changes such as translation, deformation, rotation, rearrangement and fragmentation of particles in the compaction, but also can combine the early sedimentation and the later diagenesis. The simulation of the whole rock can visualize the formation process of the whole rock, and can monitor and analyze the changes of particles and pores at any time. To ensure that the entire process method to construct digital cores is more accurate.

Description of drawings

Fig. 1 is the identification flow chart of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Embodiment 1: Please refer to Figure 1, an improved digital core modeling method, comprising the following steps:

A: Obtain rock grain characteristics. The cores were selected for sample preparation, and the size, shape, composition and distribution characteristics of rock particles in the samples were obtained by casting thin sections, particle size analysis and CT scanning.

B: Simulated rock particles. Do it in two steps:

1. Use CAD (Computer Aided Design) software to simulate the shape of real rock particles.

2. Import the particle geometry simulated by CAD into EDEM with Creator, and add particle composition and size information to complete the establishment of the particle model.

C: Sedimentation, compaction, diagenesis simulation. During the deposition process, the rock particles will go through descending and rolling until they reach the initial stable state and then enter the compaction stage, where the particles undergo changes such as translation, deformation, rotation, rearrangement and fragmentation, and then enter the diagenetic stage, where the particles are cemented, dissolved or self-generated. Increase the effect, resulting in further changes in the rock particle morphology, and finally the formation of the current rock. Use Simulator to simulate a series of changes in particles during deposition, compaction, and diagenesis.

D: Build a digital core model. After simulating a series of rock formation processes, Analyst was used to generate a digital core model.

Embodiment 2: On the basis of Embodiment 1, the CAD used in step B can be replaced by other three-dimensional software.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes within the meaning and range of the equivalents of , are included in the present invention. Any reference signs in the claims shall not be construed as limiting the involved claim.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (7)

1. an improved digital rock core modeling method, is characterized in that, comprises the following steps: A. Obtain rock particle characteristics; B. Simulated rock particles; C. Sedimentation, compaction, and diagenesis simulation; D. Build a digital core model. 2 . An improved digital core modeling method according to claim 1 , wherein the step A is specifically: acquiring rock particle characteristics. 3 . The cores were selected for sample preparation, and the size, shape, composition and distribution characteristics of rock particles in the samples were obtained by casting thin sections, particle size analysis and CT scanning. 3. a kind of improved digital rock core modeling method according to claim 1, is characterized in that, described step B is carried out in two steps: 1, simulate the shape of real rock particles with three-dimensional software; The particle geometry simulated by the software is imported into EDEM, and the particle composition and size information are added to complete the establishment of the particle model. 4. a kind of improved digital core modeling method according to claim 1, is characterized in that, in the deposition process of described step C, rock particle can experience descending, rolling, enter compaction stage after reaching initial steady state , the grains undergo changes such as translation, deformation, rotation, rearrangement and fragmentation, and then enter the diagenetic stage, the grains undergo cementation, dissolution or autogenous enlargement, resulting in further changes in the shape of rock grains, and finally the formation of the current rock. 5 . An improved digital core modeling method according to claim 1 , wherein in the step C, a Simulator is used to simulate a series of changes in particles during deposition, compaction, and diagenesis. 6 . 6. An improved digital core modeling method according to claim 1, wherein the step D is specifically: after a series of rock formation processes are simulated, use Analyst to generate a digital core model. 7. An improved digital core modeling method according to claim 3, wherein the three-dimensional software is CAD.

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