Ultra-low permeability sandstone reservoirs are significantly influenced by development of natural fractures. Based on laboratory experiments, fractured ultra- low permeability sandstone reservoirs were detailedly characterized in terms of porositypermeability relationship, micro-pore structure, stress sensitivity, and oil-water two-phase flow. The results show that permeability of fractured reservoir was higher than that of non-fractured one under equal reservoir porosity. When the reservoir porosity ranged from 10% to 20%, the permeability of fractured reservoir was approximately 2-4 times higher than that of non-fractured one. Compared with experiments on non-fractured reservoir, fractured reservoir is featured by larger throat radius span, higher proportion of largeradius throats, larger radius of dominant throats, and major contribution of large-radius throats to permeability under equal permeability. Fractured reservoir is more stress-sensitive, and the corresponding permeability loss of effective stress increase was 1-2 times higher than that of non-fractured one. Oil-water two-phase flow in fractured reservoir is featured by higher bound water and residual oil saturations, shorter common-flow interval, rapid oil relative permeability decline and water relative permeability increase with the increase of water saturation, short water-free production period, rapid water-cut increase after water break-through and low ultimate recovery factor.
SONG Xiaowei
,
QI Yadong
,
YU Rongze
,
BIAN Ya'nan
,
MA Yang
,
WANG Boyang
,
WEI Sen
. Characterization of fractured ultra- low permeability sandstone reservoirs[J]. Science & Technology Review, 2015
, 33(7)
: 20
-24
.
DOI: 10.3981/j.issn.1000-7857.2015.07.002
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