Research On Productivity Evaluation Technology Of Fracturing Oil Well Of Block X Of Ultra-low Permeability Reservoir

Oil well fracturing is currently a common and effective method for the development of low-permeability reservoirs,and the fracturing effect of oil wells directly affects the production of oil wells and the overall development effect of oil reservoirs.Therefore,the evaluation of the fracturing effect of fracturing wells in low-permeability reservoirs is an important task in judging the rationality of fracturing measures of oil wells and guiding the optimization of fracturing processes.There are many factors that affect the fracturing effect of oil wells,both geological and engineering factors,such as porosity,permeability,reservoir heterogeneity and other geological factors,fracturing displacement,sand ratio,Engineering factors such as fracture conductivity,fracture half-length,and fracture height all affect the production capacity of an oil well after fracturing.However,at present,there is insufficient research on the evaluation method of the fracturing effect of oil wells in low permeability reservoirs.In view of the above problems,this paper proposes a method of combining fine oil reservoir modeling and reservoir numerical simulation with theoretical analysis to evaluate the productivity of fracturing vertical and horizontal wells in low-permeability reservoirs.Comparative analysis of post-fracturing productivity simulation and actual values,found that the lower the displacement of the vertical well fracturing construction is,the worse the oil well commissioning effect is,and the larger the sand is,the better the fracturing effect is.In this condition,under the lower limit of surface equipment and reservoir rupture pressure,large displacement should be used for fracturing as much as possible,and the large sand ratio should be controlled as much as possible for fracturing.From the standard deviation of oil well production prediction and actual value calculation after horizontal well fracturing,it can be seen that under similar conditions of fracturing displacement,high sand ratio,open hole completion are better than low sand ratio,casing perforation completion fracturing.Furthermore,comparing the actual and predicted productivity of oil wells after fracturing of horizontal wells and vertical wells,the fracturing effect of horizontal wells in low permeability reservoirs is better than that of vertical wells.Later,through single factor analysis and orthogonal test design,multi-factor comprehensive analysis method is used to study the fracture half-length,reservoir permeability,permeability coefficient of variation,starting pressure gradient,fracture height,fracture conductivity,and oil well fracturing production.According to the influence law,it is concluded that when other design parameters of reservoir fracturing remains unchanged and the reservoir permeability increases,the production of a single well increases,indicating that as the reservoir physical properties become better,the fracturing effect of a single well also becomes better.As the reservoir heterogeneity increases,the production of fracturing wells decreases,this is mainly due to the strong heterogeneity caused by the decrease of the oil-water well communication direction and the reduction of the water flooding control area.By increasing the fracture half-length,the reservoir can be improved.The effect of layer heterogeneity on oil well productivity.With the growth of the fracture half-length,the oil well production increases,but when the fracture half-length reaches 240m,the increase in production is not obvious.This is because the fracture half-length is too long,and the fluid friction in the fracture increases,resulting in a decrease in production growth.While the fracture conductivity increases,the oil well production increases,but after the conductivity increases to 60?m~2·cm,the cumulative production becomes smoother as the conductivity increases,which is mainly because when the conductivity increases by a certain value,The decrease value of fluid resistance to/of the gap gradually becomes smaller.Finally,through the range and variance analysis of 6 factors and 5 horizontal orthogonal tests,the order of the impact of various factors on the productivity of oil wells.The optimal fracture half-length is 240m,the preferred fracture height is 45m,and the optimal fracture conductivity is 50?m~2·cm.