Rajan Kumar Prasad's theses
by
Rajan Kumar Prasad, MSE
University of Texas at Austin, 2000
Supervisor: Larry W. Lake
Heterogeneous reservoirs undergoing waterflooding contain zones in which oil in
the small-permeability zones is bypassed by water (Fogg et al., 1991; Jennings et al.,
1998; Mishra, 1993; Waggoner et al., 1992; Lucia et al., 1995; Wang et al., 1998). The
profitability of producing from heterogeneous reservoirs can be poor because of water
breakthrough in large-permeability layers (Hari Prasad Production Co., 1994). It seems
possible to improve the profitability of producing from heterogeneous reservoirs by
diverting the injected water from preferentially flowing through large to small-
permeability zones. The profitability improves because of a small increase in ultimate oil
recovery and/or a large reduction in cumulative water production. The objective of this
study is to investigate the applicability of a technology, indirect waterflooding, in
different types of heterogeneous reservoirs.
Results are based on numerical simulations of waterfloods on a generic five-spot
pattern for three different reservoir cases. The reservoirs had properties typical of a San
Andres Formation. The first case, with vertical heterogeneity, showed that ultimate oil
recovery might be improved by up to 13% original oil in place (OOIP) with indirect
waterflooding. In the second case, with areal heterogeneity and a small vertical-to-
horizontal permeability ratio (kv/kh), water production was reduced by as much as 27%.
The third case, with areal heterogeneity and a zero kv/kh, showed that water production
might be reduced by 31%. Actual recoveries are sensitive to reservoir properties,
especially to the magnitude of the vertical-permeability. Larger economic benefits are
achieved from reservoirs with smaller kv/kh.
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