The characteristic change of water cut can reflect the effectiveness of waterflooding to some extent.Early water breakthrough

fast water cut rise

and low efficiency of waterflooding have always been the obstacles preventing the development of low permeability reservoirs.Variation of water cut in waterflooding oil reservoirs involves two-phase flow of oil and water in rocks

thus is controlled by petrophysical property

oil-water features and driving force.In regard to the low permeability water-drive oil reservoirs in Shengli oilfield

we analyzed the factors influencing the variation of water cut and waterflood efficiency based on larges amounts of experimental data.These factors are characteristics of reservoir pore structure

original water saturation

stress sensitivity and displacement pressure.The results show that pore connectivity is the major factor for water cut rising

while the initial water cut mainly depends on original water saturation.Appropriate control on displacement pressure is beneficial for controlling water cut and increasing waterflood efficiency.Considering the stress sensitivity of permeability in low permeability reservoirs

we suggested the implementation of advanced water injection to avoid the permeability damage caused by pressure drop

so as to improve waterflood efficiency.