Research On Optimal Matching Of Vector Characteristics In Water-Flooding Heterogeneous Sandstone Reservoir

At present,most of the domestic water flooding sandstone reservoirs have entered the late development stage,and the production cost continues to rise.Based on the consideration of controlling the cost and improving the economic benefits,how to make more efficient use of the wells that have been in producing,further improve the recovery degree of water flooding reservoirs with less measures and low operating costs,and maintain the stable production of old wells has always been an important method to improve the economic benefits of the oilfield.To maintain the productivity stability of the old area has become an important method to maintain the economic and effective development of the oilfield.The influencing factors of water flooding reservoir development efficiency include reservoir shape,degree of heterogeneity,degree of permeability anisotropy,etc.With the increase of time and application rounds,the conventional injection and production optimization methods have little efficiency.Through the research on the optimization and matching of reservoir directional characteristics,the combination of reservoir static characteristics and water flooding development methods is of great significance to the optimization of well pattern and production in the later stage of water-flooding reservoirs.This paper starts with the study of reservoir static directivity,analyzes the influence mechanism of reservoir material source,permeability,in-situ stress and Artificial fracture,fault,structural dip angle and edge and bottom water orientation on oilfield development,and summarizes the contents of reservoir directivity;Taking permeability vector as representative,the quantitative characterization method of permeability vector characteristics is studied;Based on the relationship among paleocurrent direction,sedimentary facies and permeability direction,a permeability vectorization method based on sedimentary facies is proposed.The reservoir sedimentary characteristics and permeability scalar are organically combined into the permeability vector model,and the effectiveness of the method is verified by numerical simulation.The method established a bridge to apply reservoir sedimentary information to development numerical simulation,which deserve further research.In the dynamic aspect,the vector characteristics of water drive in the process of oilfield development are analyzed with the degree and direction of water drive as the representative,and the quantitative characterization of water drive direction is realized through the grey correlation analysis of well group.Then,taking permeability vector and well pattern as two core parameters as representatives,the optimal matching relationship between well type,well pattern and permeability vector in anisotropic formation and between well type,well pattern and artificial fracture in low permeability and ultra-low permeability reservoir are demonstrated by numerical simulation method.In terms of technical process,under the guidance of vectorization well pattern theory,according to the analysis results of reservoir vectorization characteristics and the optimization matching method,the optimal deployment principle of adjustment wells is formed.Then,the flow field optimization algorithm is developed.The algorithm takes the balanced flow field or common production index as the objective function,the well type,perforation space location limit,injection and production speed limit as the boundary conditions,and the deployment principle as the constraint condition to establish the optimization mathematical model.The genetic algorithm is used to solve the model.In view of the complexity of the adjustment scheme in the adjustment process of the old liberated area,the classical genetic algorithm is improved,the individual validity checking module is added,and the improved multi-objective optimization genetic algorithm is established to achieve the automatic optimization.Combined with computer programming technology,a software is developed to achieve multi-objective injection production optimization considering reservoir vector characteristics.Taking wen51 north area of Pucheng Oilfield as an example,the analysis of reservoir directivity,the design of vectorization adjustment scheme,the simulation solution of optimization scheme and the prediction comparison of optimization scheme are carried out;In the initial stage of the optimization scheme,the oil increase is increased by 20 t /d,and the comprehensive water cut is reduced by about2%,which proves the effectiveness of the vector feature optimization matching technology and related optimization algorithms.