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CN-121995531-A - Three-dimensional ground stress prediction method based on structural deformation and numerical simulation

CN121995531ACN 121995531 ACN121995531 ACN 121995531ACN-121995531-A

Abstract

The invention discloses a three-dimensional ground stress prediction method based on structural deformation and numerical simulation, which comprises the following steps of S100, constructing large deformation simulation, S110, establishing a three-dimensional frame model by utilizing depth domain horizon data according to an earthquake interpretation result, S120, setting a self-constructed model and a strain softening mode, S130, setting stratum mechanical parameters, S140, setting boundary conditions, S150, setting speed boundary loading, S160, comparing strain distribution in a simulation result with fault distribution obtained through geological exploration, checking the correctness of the structural large deformation simulation result, S200, constructing small strain simulation, using the simulation result of the first stage as an initial model, modifying the speed boundary loading into the stress boundary loading, and comparing the stress distribution and the actual measurement result of the simulation result.

Inventors

  • HU BO
  • LIANG CHENGCHUN
  • WU JINWEI
  • REN HENG
  • LIU XIAOHU
  • YANG ZHE

Assignees

  • 中国石油化工股份有限公司
  • 中国石油化工股份有限公司华北油气分公司

Dates

Publication Date
20260508
Application Date
20241108

Claims (7)

  1. 1. The three-dimensional ground stress prediction method based on structural size deformation and numerical simulation is characterized by comprising the following steps of: S100, constructing large deformation simulation; The method specifically comprises the following steps: s110, establishing a three-dimensional frame model by utilizing depth domain horizon data according to the seismic interpretation result; s120, setting a constitutive model and a strain softening mode; S130, setting stratum mechanical parameters; s140, setting boundary conditions; S150, setting speed boundary loading, including the speed and the speed direction; S160, performing numerical calculation, comparing strain distribution in the simulation result with fault distribution obtained through geological exploration, and checking the correctness of the large deformation simulation result; s200, constructing small strain simulation; The method specifically comprises the following steps: s210, using a simulation result of the first stage as an initial model of the stage, and modifying the speed boundary loading into stress boundary loading; s220, performing numerical calculation, and comparing the stress distribution of the simulation result with the actual measurement result.
  2. 2. The method according to claim 1, wherein in the step S120, the constitutive model includes an elastic constitutive model, a mor coulomb elastoplastic constitutive model, and a berger creep constitutive model.
  3. 3. The method according to claim 2, wherein in the step S120, the strain softening mode is set such that the mechanical strength of the rock layer decreases with increasing strain, including decreasing internal friction angle.
  4. 4. The method according to claim 1, wherein in the step S130, the setting of the formation mechanical parameters includes setting the formation mechanical parameters according to the lithology of the well, the core mechanical experiment, and the empirical range.
  5. 5. The method according to claim 4, wherein in the step S130, when the constitutive model is a mor coulomb elastoplastic constitutive model, the mechanical parameters of the stratum include density, young 'S modulus, poisson' S ratio, internal friction angle, cohesion, tensile strength, tangential stiffness, and normal stiffness.
  6. 6. The method according to claim 1, wherein in the step S140, the boundary conditions include three types of fixed, sliding, and free.
  7. 7. The method according to claim 1, wherein in the step S210, the stress boundary loading includes normal stress and/or shear stress, and stress magnitude and stress direction.

Description

Three-dimensional ground stress prediction method based on structural deformation and numerical simulation Technical Field The invention relates to the technical field of geological exploration, in particular to a three-dimensional ground stress prediction method based on structural size deformation and numerical simulation. Background Ground stress is a natural stress stored in the earth rock formations, and generally includes vertical stress caused by formation gravity and structural stress caused by deformation of geologic formations. The change of stress state with the spatial point is called the ground stress field. The effect of ground stress is widely existed in human activities, such as in oil and gas well fracturing, the space distribution of a fracture is restrained by the ground stress, in tunnel excavation, a high ground stress section is at risk of causing rock burst so as to endanger engineering safety, and in natural earthquake prediction, a high ground stress earthquake dead zone is an important monitoring area. Thus, fine measurement and prediction of ground stress is critical to these projects. Measurement of ground stress accurate ground stress at the measurement site can be obtained by a hydraulic fracturing method, a borehole stress relief method, an acoustic emission method, or the like. However, for complex structural deformation zones, the results of a few measurement points are far from reflecting the stress field characteristics of the entire three-dimensional space. Accordingly, engineers have attempted to predict three-dimensional ground stress distribution by numerical modeling techniques, with the "hard data" of these measurement points as constraints. Common numerical simulation methods include finite element methods, finite difference methods, discrete element methods, boundary element methods, variational methods, and the like. Regardless of which method is used, however, current simulation techniques essentially do not take into account the process of long-term structural deformation, using only the results of the long-term structural deformation as the initial geologic model of the numerical simulation. Modeling is carried out through a construction partition and an embedded fracture weak zone, then stress boundaries are loaded, and stress field distribution in a three-dimensional space is obtained based on stress balance calculation. This method belongs to the small strain numerical simulation and is feasible for constructing areas with relatively simple deformations. However, for complex regions of structural deformations, especially those of the fourth and later ages, a large number of fractures of different levels, geometric shapes and mechanical states are distributed, and these complex deformations are difficult to handle by geologic modeling. In addition, stress and strain relief are related, and the structural deformation history since the fourth century profoundly influences the current stress field distribution. In the prior art, the patent with the publication number of CN117272728A provides a three-dimensional ground stress field prediction method aiming at a complex structural band, and provides a method for constructing a three-dimensional geologic body mechanical model in advance and calculating dynamic rock mechanical elastic parameters corresponding to a small interval according to logging data. And then, stress field prediction is established, and finally, integral ground stress field inversion calculation is carried out by adopting a finite element method, wherein the method plays a certain role in macroscopic large deformation simulation, but the problem of combination with a small strain scale cannot be effectively solved. Based on the current situation, we propose a three-dimensional ground stress prediction method based on structural deformation and numerical simulation, and by means of numerical calculation, faults and stress fields are generated, and compared with the conventional small-strain numerical simulation, only the stress field results are obtained, and the simulation method provided by the invention has more sufficient constraint conditions. Disclosure of Invention The invention aims to provide a three-dimensional ground stress prediction method based on structural deformation and numerical simulation, which increases model constraint and improves reliability of three-dimensional ground stress prediction results by constructing numerical calculation of two stages of large deformation numerical simulation and small strain numerical simulation. The invention discloses a three-dimensional ground stress prediction method based on structural deformation and numerical simulation, which comprises the following steps: S100, constructing large deformation simulation; The method specifically comprises the following steps: s110, establishing a three-dimensional frame model by utilizing depth domain horizon data according to the seismic interpretatio