Based on core

thin section

SEM

well logging data and performance analysis and guided by reservoir configuration theory

configuration analysis of thick mouth bar sandstone in the second block in Shengtuo oilfield was carried out at three levels including composite mouth bar

single mouth bar and internal accretion within single mouth bar.On this basis

reservoir quality distribution patterns of different configuration units were analyzed.Result indicates that reservoir parameters of different configuration units are significantly different.Class Ⅰ and Ⅱ reservoirs mainly occur in the major parts of mouth bars.Class Ⅲ reservoir is generally distributed on flanks of mouth bar and under interlayers in the interior of mouth bars

while Class Ⅳ reservoirs mainly occur in sheet sands.In addition

dynamic characteristics of reservoir parameters in different configuration unit during waterflooding were discussed by using performance data.The reservoir porosity increased during waterflooding as a whole

but changed slightly.The largest increase appeared in the center of mouth bar

followed by bar flank

and nearly no changes occurred in sand sheet.In contrast

reservoir permeability showed different trends in different configuration units.Some units increased while others decreased.With constant flushing of injected water

effective permeability increased in high or ultra-high permeability reservoirs such as mouth bar center

decreased in middle or low permeability reservoirs like bar flanks and underwater distributary channels and remained unchanged in low-permeability sheet sand.The amplitude of porosity increase was much smaller than that of permeability.Median grain size of different configuration units all increased to some extent at both low and high water-cut stages

while clay content decreased.