Based On THM Study Mechanism And Law Of Sand Production In Heavy Oil Thermal Recovery Wells

Injecting hot fluid for viscosity-reducing exploitation is one of the most effective development methods for heavy oil reservoirs.Under the action of high temperature and high pressure fluids,the reservoir pressure and temperature change significantly,and the stress field around the well is also changed,which may cause significant deformation and destruction of the reservoir rock around the wellbore,causing serious sand production.By predicting and analyzing sand production under different production conditions through numerical simulation methods is one of great significance to the optimization of the production system.Firstly,in this paper,the mechanical experiments were carried out for heavy oil reservoir rocks,so get the fundamental parameters of heavy oil reservoir rocks,and obtain the deformation laws under different temperature conditions,then providing basic data for numerical simulation analysis.Secondly,based on rock mechanics,seepage mechanics and heat transfer theory,comprehensive consideration stress distribution and elasto-plastic deformation of reservoir rocks,oil-water two-phase flow,heat conduction and thermal convection and so on,Finally,established a THM mathematical model of oil thermal recovery.Based on the Galerkin finite element method,the mathematical equations of the model are spatially discretized,and the difference is discretized in the time domain by the backward difference method to obtain the finite element equation of rock deformation and failure analysis in the process of heavy oil thermal injection.Based on the discrete finite element method,based on the secondary development function of the ABAQUS finite element software,a corresponding subroutine for the deformation and failure of the rock-fluid-solid coupling analysis unit was developed.Finally,taking a certain L oilfield in Bohai as an example,this paper establishes a finite element model for analyzing the deformation and failure of rock during the hot fluid injected to heavy oil reservoir.Based on the equivalent plastic strain as sand production criteria in the reference literature,Through the analysis of the deformation and failure and the sand production mechanism of the reservoir caused by the injection of hot fluid to the heavy oil.The analysis of the in-situ stress,temperature,pore pressure,and the effect of reservoir sand production on parameters such as injection fluid temperature,injection time,and injection fluid velocity were carried out.The analysis results show that with the increase of the injected fluid temperature,the injection time and the injected fluid velocity,the potential sand production range of the reservoir around the well becomes larger,and the influence of the injected fluid velocity is the most significant.From the calculation results,when the injection rate increases to a certain extent,the potential sand production area near the well-period increases rapidly.The results of numerical analysis in this paper can provide a reference for optimization of thermal parameters of heavy oil thermal recovery.