The calculation of heterogeneous aggregative index

together with its function and significance

is briefed based on the data acquired from the Block Ⅱof Shengtuo oilfield.The 3-D modeling of heterogeneous aggregative index by employing the reservoir stochastic method includes the following five stages:preparation of reservoir data

construction of model

analysis of heterogeneous aggregative index

construction of heterogeneous model

and display of modeling results.The spatial heterogeneity of reservoir is vividly characterized by the model.An analyze of the variation function and 3-D model characteristics of heterogeneous aggregative index of sandstone in the Third Member of Dongying Formation in its earlier

middle

and later stages of development reveals the changing pattern of reservoir heterogeneity at different development phases.According to the results

the range of influence(a)decreases with waterflooding

while the sill value(c

o

+c)increases and nugget value(c

o

)remains zero.The initial

middle and late development stages are characterized by moderate

moderate to relatively strong

and strong reservoir heterogeneities

respectively.Vertically

the heterogeneous aggregative index varies greatly in the upper part of the reservoir and is more constant in the lower part.Vertical interformational and intra-formational heterogeneities are stronger than lateral heterogeneity.Water injection intensifies the heterogeneity of reservoirs.