Prediction and analysis on productivity of vertically fractured wells in low-permeability oil reservoirs

Fracturing stimulation technology is widely applied in the development of low-permeability oil reservoirs, and the stimulation effect of different fracturing plans is different.To realize the expected stimulation effect, it is of great significance to optimize fracturing design by researching the postfrac productivity.In this paper, a seepage model combining radial flow with bilinear flow was established for vertically fractured wells in low-permeability oil reservoirs according to the permeability characteristics of formations around vertically fractured wells.Then, the productivity formulas of infinite-conductivity and finite-conductivity fractures in low permeability oil reservoirs were derived to deal with the starting pressure gradient of low-permeability oil reservoirs.The error between the calculation result of finite-conductivity fracture productivity formula and the field data is lower than 7%.Productivity curves for different influential factors were plotted on the basis of the basic parameters of thick conglomerate oil reservoir with extra low permeability in a certain block of the Junggar Basin, and then they were analyzed.It is shown that the fracture conductivity can't be approximated as the infinite conductivity until it reaches a certain value, or the error will be higher.In order to realize the expected stimulation effect in the current economic conditions, all fracturing parameters shall match reservoir conditions.