CN-122021198-A - Acidizing fracturing stratum parameter prediction method based on multi-physical field coupling

CN122021198ACN 122021198 ACN122021198 ACN 122021198ACN-122021198-A

Abstract

The application discloses an acidizing and fracturing stratum parameter prediction method based on multi-physical field coupling, and relates to the field of oil and gas field development engineering and multi-physical field coupling numerical simulation. Aiming at the problem that the conventional single-field model cannot comprehensively describe the complex behavior of the acid liquor corrosion stratum, the dynamic high-precision prediction of the key stratum parameters such as porosity, permeability, temperature, rock mechanical parameters, acid liquor concentration field, solid displacement and the like in the acidizing and fracturing process is realized by constructing a flow-solid-heat-chemical multi-physical-field coupling equation set covering fluid flow, chemical reaction, heat conduction and solid deformation and combining finite element space dispersion and step-by-step iterative solution. The application can provide theoretical basis and technical support for optimizing the acid liquor reconstruction scheme of the gas storage and hydraulic fracturing engineering design.

Inventors

TANG JIZHOU
FANG HONGMING
YANG MIAO
JIANG YUNQI
HUANG LEI
YANG JIAN
CHEN WEIHUA
WANG HANCHENG
JIA YUCHENG
HAN HUIFEN
LI LI
ZENG JI

Assignees

同济大学

Dates

Publication Date: 20260512
Application Date: 20260414

Claims (10)

1. The acidizing and fracturing stratum parameter prediction method based on the multi-physical field coupling is characterized by comprising the following steps of: Constructing a multi-physical field equation set for describing fluid flow, chemical reaction, heat conduction and solid deformation behaviors in the process of acidizing and fracturing stratum, wherein the multi-physical field equation set comprises a fluid flow control equation, a chemical reaction and porosity evolution equation, a heat conduction control equation and a solid deformation control equation; Coupling equations in the multi-physical field equation set to obtain a flow-solid-heat-chemical multi-physical field coupling equation set; Performing discretization treatment on the flow-solid-heat-chemical multi-physical field coupling equation set, and performing step-by-step iterative solution on the discretized flow-solid-heat-chemical multi-physical field coupling equation set until a preset end condition is met and iteration is finished to obtain a stratum parameter prediction result, wherein the stratum parameter prediction result comprises porosity, permeability, temperature, rock mechanical data, acid liquor concentration field and solid displacement distributed along a space path in an acidizing and fracturing process, and the preset end condition comprises that the difference value between the porosity reaching a preset time threshold or the current iteration and the preset porosity threshold is smaller than a preset difference value.
2. The method for predicting parameters of an acid fracturing formation based on multi-physical field coupling of claim 1, wherein the flow-solid-thermal-chemical multi-physical field coupling relation equation set specifically comprises: Fluid-solid coupling equations, fluid-chemical coupling equations, thermo-solid coupling equations, fluid-thermal coupling equations, and chemical-solid coupling equations.
3. The method of claim 1, wherein the fluid flow control equations comprise a formation and fracture zone control equation and a wellbore zone control equation; The control equation for the formation and fracture zone is obtained by the following equation: ; ; the wellbore zone control equation is derived by the following equation: ; ; Wherein, the Representing the porosity of the i region; , And Respectively representing rock matrix and artificial fracture; Representing fluid density; the Darcy speed of the region i is represented, and t represents time; Representing a gradient operator; Representing the fluid pressure in region i; An expression representing a unit tensor for pressure and stress tensors; representing the stress tensor of the i region; Indicating the viscosity of the fluid; Representing the inverse of the permeability of the i-zone; representing the nonlinear drag coefficient of the i region; a quality source item representing an i region; representing the external force of region i; A fluid velocity representative of a wellbore region; Representing fluid pressure in a wellbore region; Representing the external force of the wellbore region.
4. The method for predicting parameters of an acid fracturing stratum based on multi-physical field coupling according to claim 1, wherein the chemical reaction and porosity evolution equation comprises an acid liquor concentration transport equation and a porosity evolution equation; The acid liquor concentration transport equation is as follows: ; The porosity evolution equation is: ; Wherein, the Representing the porosity of the i region; , And Respectively representing rock matrix and artificial fracture; the acid liquor concentration of the region i is represented, and t represents time; darcy speed representing region i; Representing a gradient operator; representing the mechanical dispersion coefficient of the i region; a molecular diffusion coefficient representing the i region; indicating a source of change in acid concentration caused by the chemical reaction; Indicating the mass source of the acid liquor in the region i; indicating a reaction rate constant; indicating the concentration of acid at the reaction surface; represents a specific surface area; Representing the amount of material available to react with the rock surface per unit pore volume; Representing rock density.
5. The method for predicting parameters of an acid fracturing formation based on multiple physical field coupling of claim 1, wherein the thermal conductivity control equation is: ; Wherein, the Representing the thickness of the model; Representing fluid density; Representing the specific heat capacity of constant pressure; Darcy speed representing region i; T represents temperature; Representing thermal conductivity; representing a heat source item; Representing a heat source.
6. The method for predicting parameters of an acid fracturing formation based on multiple physical field coupling of claim 1, wherein the solid deformation control equation is: ; Wherein, the Representing rock density; Representing the porosity of the i region; , And Respectively representing rock matrix and artificial fracture; Representing solid displacement; Representing a stress tensor; Representing a volumetric force vector; Represents the Biot coefficient; Representing a gradient operator; indicating the fluid pressure in region i.
7. The method for predicting the parameters of the acidizing and fracturing stratum based on the multi-physical field coupling, which is disclosed in claim 1, is characterized by performing discretization on a flow-solid-heat-chemical multi-physical field coupling equation set, and specifically comprises the following steps: Performing grid division on a fluid flow control equation, a chemical reaction and porosity evolution equation, a heat conduction control equation and a solid deformation control equation in a multi-physical field equation set by adopting a self-adaptive grid encryption method; Performing space dispersion on corresponding equations in the multi-physical field equation set by adopting a finite element method on the divided grids to obtain a discretized multi-physical field space equation set; and performing time dispersion on the discrete multi-physical-field space equation set to obtain a discrete multi-physical-field space-time equation set comprising a plurality of time steps, wherein the discrete multi-physical-field space-time equation set comprises a space-time discrete fluid flow equation, a space-time discrete chemical transport equation, a space-time heat dissipation conduction equation and a space-time discrete solid deformation equation.
8. The method for predicting the parameters of the acidizing and fracturing stratum based on the multi-physical field coupling according to claim 1, wherein the step-by-step iterative solution is performed on the discretized flow-solid-heat-chemical multi-physical field coupling equation set until the iteration is finished after the preset end condition is met, and the formation parameter predicting result is obtained, and the method specifically comprises the following steps: calculating a numerical solution of a multi-physical field of the current iteration of the time step t, wherein the multi-physical field comprises a fluid pressure field, a fluid velocity field, an acid liquid concentration field, a temperature field and a solid displacement field, and the numerical solution of the multi-physical field is obtained by sequentially solving a space-time discrete fluid flow equation, a space-time discrete chemical transport equation, a space-time heat dissipation conduction equation and a space-time discrete solid deformation equation in a discrete multi-physical field space-time equation set according to a flow-solid-heat-chemical multi-physical field coupling relation equation set; judging whether the numerical solution of the multiple physical fields in the current iteration in the time step t meets a preset convergence condition or not, wherein the preset convergence condition comprises that the variation of the fluid pressure, the fluid speed, the acid liquid concentration, the temperature and the solid displacement in the numerical solution of the multiple physical fields in the current iteration in the time step t and the numerical solution of the multiple physical fields in the last iteration are smaller than respective corresponding preset variation thresholds; If the preset convergence condition is not met, reducing the time step or increasing the iteration times, and returning to the step of calculating the numerical solution of the time step t in the multiple physical fields of the current iteration until the preset convergence condition is met; If the preset convergence condition is met, let t=t+1, return to step "calculate the numerical solution of multiple physical fields of time step t in the current iteration", until the preset ending condition is met, finish iteration, get the stratum parameter prediction result.
9. The method for predicting parameters of an acid fracturing formation based on multi-physical field coupling according to claim 8, wherein calculating a numerical solution of the multi-physical field at the current iteration of time step t comprises: Solving a space-time discrete fluid flow equation by a Newton iteration method based on the porosity, permeability, density and viscosity of the previous iteration to obtain a numerical solution of a fluid pressure field and a fluid velocity field of the current iteration; according to the numerical solution of the fluid pressure field of the current iteration, the stress boundary condition in the space-time discrete solid deformation control equation of the current iteration is updated by combining the fluid-solid coupling equation; According to the numerical solution of the fluid velocity field of the current iteration, solving a space-time discrete chemical transport equation by combining a chemical reaction dynamics principle to obtain the numerical solution of the acid solution concentration field of the current iteration; According to the chemical-solid coupling equation, the elastic modulus and Poisson's ratio parameters in the space-time discrete solid deformation control equation of the current iteration are updated by combining the porosity after the first updating of the current iteration; Utilizing the numerical solution of the fluid velocity field, the numerical solution of the acid liquid concentration field and the porosity after the first updating of the current iteration to solve a space-time heat dissipation conduction equation to obtain the numerical solution of the temperature field of the current iteration; updating the chemical reaction rate constant of the current iteration by combining a thermal-chemical coupling equation according to the temperature field value solution and the acid solution concentration field value solution of the current iteration, and updating the permeability, the density and the viscosity of the current iteration for the second time by combining the temperature field and the acid solution concentration field of the current iteration according to the fluid-chemical coupling equation; substituting the updated chemical reaction rate constant into a space-time discrete chemical transport equation, and solving the space-time discrete chemical transport equation again to obtain a numerical solution of the acid liquor concentration field after the current iteration update; combining the numerical solution of the temperature field of the current iteration, and updating the thermal stress related parameters in the solid deformation control equation of the current iteration according to the thermal-solid coupling equation; meanwhile, according to a fluid-thermal coupling equation, updating the specific heat capacity and the heat conductivity coefficient of the current iteration fluid; Based on the updated stress boundary conditions, the thermal stress related parameters, the elastic modulus, the Poisson ratio parameters and the porosity after the first update, solving a space-time discrete solid deformation equation of the current iteration to obtain a numerical solution of a solid displacement field of the current iteration, and updating the porosity after the first update of the current iteration for the second time.
10. The method for predicting parameters of an acid fracturing formation based on multi-physical field coupling of claim 9, wherein calculating a numerical solution of the multi-physical field at the current iteration of time step t further comprises solving by a preconditioned conjugate gradient method.

Description

Acidizing fracturing stratum parameter prediction method based on multi-physical field coupling Technical Field The application relates to the field of oil and gas field development engineering and multi-physical field coupling numerical simulation, in particular to an acidizing fracturing stratum parameter prediction method based on multi-physical field coupling. Background Acid liquor reformation and hydraulic fracturing of deep oil and gas reservoirs are important technical means for improving the recovery ratio and peak shaving capacity of reservoirs. The process of acid liquor corrosion of the stratum involves complex coupling behaviors of multiple physical fields such as fluid flow, solid deformation, heat conduction, chemical reaction and the like, and can obviously change the porosity, permeability and mechanical properties of the stratum, thereby influencing the compressibility and fracturing effect of the reservoir. However, researches on acid corrosion formations in the related art are focused on analysis of a single physical field (such as chemical reaction or fluid flow), and lack of comprehensive description on coupling effects of multiple physical fields leads to difficulty in accurately predicting dynamic evolution rules of formation parameters in the acid modification process. In addition, the influence of temperature change on chemical reaction rate and fluid physical properties is often ignored by the related model, and interaction of formation stress and pore pressure is not fully considered, so that optimization of acid liquor reconstruction design and improvement of gas storage recovery efficiency are limited. Therefore, a method for predicting the formation parameters of the acidizing and fracturing based on multi-physical field coupling is needed to realize dynamic high-precision prediction of the formation parameters in the acidizing process, and provide theoretical guidance for modification of acid liquor in a gas storage. Disclosure of Invention The application aims to provide an acidizing and fracturing stratum parameter prediction method based on multi-physical field coupling, which can solve the problems that in the prior art, multi-physical field coupling analysis is lacked and a stratum parameter dynamic evolution rule in an acid liquor corrosion process cannot be accurately predicted. By constructing a mathematical model of fluid flow, solid deformation, heat conduction and chemical reaction four-field coupling and combining a finite element discrete and step-by-step iterative solution method, the accurate simulation of acid corrosion stratum behaviors is realized, and theoretical basis is provided for acid liquid transformation and hydraulic fracturing design of the gas storage. In order to achieve the above object, the present application provides the following solutions: The application provides an acidizing and fracturing stratum parameter prediction method based on multi-physical field coupling, which comprises the following steps: And constructing a multi-physical field equation set for describing fluid flow, chemical reaction, heat conduction and solid deformation behaviors in the process of acidizing and fracturing the stratum, wherein the multi-physical field equation set comprises a fluid flow control equation, a chemical reaction and porosity evolution equation, a heat conduction control equation and a solid deformation control equation. And coupling equations in the multi-physical field equation set to obtain the flow-solid-heat-chemical multi-physical field coupling equation set. Performing discretization treatment on the flow-solid-heat-chemical multi-physical field coupling equation set, and performing step-by-step iterative solution on the discretized flow-solid-heat-chemical multi-physical field coupling equation set until a preset end condition is met and iteration is finished to obtain a stratum parameter prediction result, wherein the stratum parameter prediction result comprises porosity, permeability, temperature, rock mechanical data, acid liquor concentration field and solid displacement distributed along a space path in an acidizing and fracturing process, and the preset end condition comprises that the difference value between the porosity reaching a preset time threshold or the current iteration and the preset porosity threshold is smaller than a preset difference value. According to the specific embodiment provided by the application, the application has the following technical effects: The application provides an acidizing and fracturing stratum parameter prediction method based on multi-physical field coupling, which solves the problem that the traditional single field model cannot fully describe the complex process of acidizing and fracturing by constructing a multi-physical field equation set covering fluid flow, chemical reaction, porosity evolution, heat conduction and solid deformation, realizes systematic description of multi-physical fiel