Premium
Mechanisms for trapping and mobilization of residual fluids during capillary‐dominated three‐phase flow in porous rock
Author(s) -
Helland J. O.,
Jettestuen E.
Publication year - 2016
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2016wr018912
Subject(s) - capillary pressure , capillary action , residual oil , porous medium , displacement (psychology) , mechanics , multiphase flow , phase (matter) , two phase flow , materials science , capillary number , geology , porosity , hysteresis , flow (mathematics) , geotechnical engineering , petroleum engineering , chemistry , composite material , physics , psychology , organic chemistry , psychotherapist , quantum mechanics
We use a multiphase level set approach to simulate capillary‐controlled motions of isolated fluid ganglia surrounded by two other continuous fluids (i.e., double displacements) during three‐phase flow on 3‐D porous rock geometries. Double displacements and three‐phase snap‐off mechanisms are closely related. Water snap‐off on gas/oil interfaces can initiate double displacements that mobilize isolated oil ganglia in water‐wet rock, but it can also terminate ongoing double displacements and trap oil in water. The multiphase level set approach allows for calculating the evolution of disconnected‐phase pressure during the motion. In the events of pore filling by double displacement of oil ganglia, and water snap‐off on gas/oil interfaces, we find that the local gas/oil capillary pressure drops, while local oil/water capillary pressure increases, by a similar magnitude as observed for the capillary pressure drops during single‐pore filling events in dynamic pore‐scale experiments of two‐phase drainage. We also find that oil ganglia decrease their surface area, and achieve a more compact shape, when the gas/oil interfacial area decreases at the expense of increased oil/water interfacial area during double displacement. By comparison with similar two‐phase gas/water simulations, we find that the level of the gas/water capillary pressure curves, including hysteresis loops, are smaller when a mobile, disconnected oil is present, which suggests double displacement of oil is more favorable than direct gas/water displacement. We also present cases in which phase trapping occurred in the three‐phase simulations, but not in the corresponding two‐phase simulations, supporting the view that more trapping is possible in three‐phase flow.