Numerical Simulation And Development System Optimization Of Water Injection Huff And Puff In Tight Oil Reservoirs

At present,tight oil has become an important resource to replace conventional oil and gas energy,and exploration and development technology has also developed rapidly.Horizontal well volume fracturing technology has enabled tight oil reservoirs to be effectively developed.The complex fracture network structure greatly increases the difficulty of accurate simulation of tight reservoirs.At the same time,due to the high fracturing cost,the development of fracturing horizontal wells in tight reservoirs has the problem of unbalanced productivity and economic benefits.Therefore,combined with the horizontal well water injection huff and puff development method,this paper conducts accurate numerical simulation and development system optimization research on fractured tight oil reservoirs.First,combined with the embedded discrete fracture model and the equivalent method of property homogenization in the SRV area,a conceptual model of water injection huff and puff for tight oil reservoirs is established by comprehensively considering the threshold pressure gradient,permeability stress sensitivity effect and imbibition effect,and analyze the effect of seepage mechanism on productivity.Secondly,single-factor and global sensitivity analysis methods are used to determine the optimization parameters and their optimization ranges,and analyze the second-order interaction effects between the parameters.Then,taking the cumulative oil production and the NPV as the optimization goals,the multi-objective particle swarm algorithm is used to optimize the parameters of the development system,and obtain the optimal solutions which balance the cumulative oil production and the NPV.Finally,the optimal parameter scheme is applied to the actual reservoir development.The simulation test of the conceptual model shows that the combination of the embedded discrete fracture model and the equivalent method of property homogenization in the SRV area improves the accuracy of the characterization of complex fracture networks and can accurately simulate fractured tight reservoirs.Through sensitivity analysis and comparison experiments,it is found that the half-length of fractures,bottom hole flow pressure and water injection rate are greatly influenced by the interaction of other parameters.The single-objective optimization results show that there is an optimization conflict between the cumulative oil production and the net present value.When the net present value is the largest,the cumulative oil production is not the largest,and vice versa.The multi-objective optimization method based on Pareto can find the best parameter scheme that effectively balances production capacity and economic benefits.The optimization method has strong adaptability and reliability in actual tight oil reservoirs,provides reference for the design of reservoir development plans,and guides actual oilfield work,which is of great significance for in-depth research.