Pore Network Modeling of Fissured and Vuggy Carbonates
Carbonate
rocks contain most of the world’s proven hydrocarbon reserves. It is essential
to predict flow properties and understand flow mechanisms in carbonates for
estimating hydrocarbon recovery accurately. Pore network modeling is an effective
tool in determination of flow properties and investigation of flow mechanisms.
Topologically equivalent pore network models yield
accurate results for flow properties. Due to their simple pore structure,
sandstones are generally considered in pore scale
studies and studies involving carbonates are limited. In this study, in order
to understand flow mechanisms and wettability effects
in heterogeneous carbonate rocks, a novel pore network model
was developed for simulating two-phase flow. The constructed model was composed
of matrix, fissure and vug
sub domains and the sequence of fluid displacements was simulated typical by
primary drainage followed by water flooding. Main mechanisms of imbibition, snap-off, piston like advance and pore body
filling, were also considered. All the physically
possible fluid configurations in the pores, vugs and fissures for all wettability
types were examined. For configurations with a fluid layer sandwiched between
other phases, the range of capillary pressures for the existence of such a
layer was also evaluated. Then, results of the
proposed model were compared with data available in
literature. Finally, effects of wettability and pore
structure on flow properties were examined by
assigning different wettability conditions and
porosity features. It was concluded that the proposed pore network model
successfully represented two phase flow in fissured
and vuggy carbonate rocks.
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