Study On Prediction Model Of Fracturing Productivity Of Horizontal Wells In Fuyu Reservoir In Block A Of Daqing Oilfield

With the development of reservoir exploration,the proportion of medium and high permeability reservoirs is less and less,and the efficient development of low permeability reservoirs becomes more and more important.Due to low porosity,small throat and poor permeability of tight reservoir,large-scale fracturing is needed to produce effectively.Fuyu reservoir in block A of Daqing field has been developed by the way of shut-in after fracturing of horizontal wells and achieved good initial results.However,the lack of understanding of the law of production decline in the later stage of fracturing and the lack of an effective prediction model have affected the accurate design of the later stage production system.In view of the above problems,this paper carries out evaluation experiments of reservoir physical properties such as porosity,permeability,wettability,water saturation,capillary force and relative permeability curve,the main control factors and the numerical simulation analysis of the influence rule of the horizontal well fracturing productivity,as well as the construction of the horizontal well fracturing productivity prediction model,the main results are as follows:(1)The main mineral components of the tight reservoir in the working area are plagioclase,quartz and clay minerals;the porosity of the reservoir is 2.83?12.8%,the average porosity is8.58%,the permeability is 0.5707?1.2857 m D,the average permeability is 1.037 m D;The original oil saturation range is 0.53?0.62,the average initial oil saturation is 0.57;the contact angle is 63.5°,and the core is of hydrophilic type.(2)Based on the geological data and physical properties of the block,the fracturing numerical model of dual-medium multiphase flow horizontal well is established,and the fracturing productivity of horizontal well under different geological and engineering factors is simulated,the influence law of geological and engineering factors on productivity is clarified.(3)Using the method of grey correlation analysis,taking the peak oil production and cumulative oil production as evaluation indexes,the grey correlation values of reservoir factors,fracture parameters and production parameters with the two indexes are calculated,and the order of main controlling factors is determined.The results show that the grey correlation degree of reservoir thickness,oil saturation,number of fractures,half-length of fractures,fracture permeability,production pressure difference with daily peak oil production and cumulative oil production is greater than 0.5,all should be taken into account in the establishment of predictive models.(4)The effects of reservoir thickness,oil saturation,number of fracture clusters,halflength of fracture,fracture permeability and production pressure difference on peak oil production and production decline in horizontal well fracturing are analyzed.The peak daily oil production prediction model and the fracturing productivity prediction model of horizontal well are established and applied in the field.The results show that the model is in good agreement with the actual well and can effectively guide the design of post-fracturing production system.