Quantitative Analysis And Application Of Natural Fracture Development Degree In Low Permeability Reservoirs In Erdos Basin

The Erdos Basin is rich in oil resources,and with the action of tectonic movement and diagenesis,the low permeability reservoirs produce natural microfractures.At present,the quantitative analysis of the development degree of natural fractures isn't mature,and the reservoir fractured geological models is difficult to make.The oil well production of the low permeability reservoir is closely related to the degree of fracture development,and the accuracy of the existing production forecasting model is not high.Therefore,quantifying the development degree of the natural fractures,making the fractured model of low permeability reservoir and establishing a prediction model considering the development of fractures is significance to the development of low permeability reservoir.In this paper,the natural microfractures at the microns scale are proven widely developed in the low permeability reservoirs of the Erdos Basin from theoretical analysis and rock mechanics experiments,they play the role of large throat and improve the permeability of the reservoirs.Based on the fractal theory,the fractal development degree index is introduced to quantify the development degree of microfractures.The fracture development index model of Chang3 fractured low permeability reservoir in Weibei Oilfield was established by using the Kriging method based on the reservoir matrix model.At the high value area of fracture development index,the average liquid production is 5.5m3/d.Depending on the results of quantitative analysis of the development of fractures,the prediction model of vertical fractured well productivity of fractured low permeability reservoirs was established.Based on seepage theory,the influence of the development degree of fractures on the productivity of Chang3 reservoir was analyzed,and the natural fractures is the key factor that affects the oil production of low-permeability reservoirs.The fracturing scale can be expanded in the microfracture relative development zone,which can greatly improve the oil productivity.At the same time,low damage fracturing fluid system should be used in the fracturing process,which is important for the efficient development of low permeability reservoirs.