Abstract: Based on water flooding test,3D network model of long term water flooded sand reservoir pore throat structure variation is constructed to analyze its variation law by using the 3D particle migration model and finite difference solution method.The result indicates that the throat radius and its variation range increase after long term water flooding behavior while radius of the minima throat decreases.The distribution pattern of channels which includes the original larger radius throats and the big pores after water flooding is determinated by the original rock structure.In fact,not all the channels are connected to each other all over the pore scale network and form a crossed channel,but several big radius pores in the start and end face of the pore scale network are connected to each other and formed a channel group.The modeling result together with oil well testing can provide more reasonable solution to the adjustment of injection profile.

Key words: water flooded sand reservoir, pore throat structure, water flooding test, network modeling