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Relative permeability and trapping of CO 2 and water in sandstone rocks at reservoir conditions
Author(s) -
Krevor Samuel C. M.,
Pini Ronny,
Zuo Lin,
Benson Sally M.
Publication year - 2012
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 - 10.1029/2011wr010859
Subject(s) - geology , relative permeability , capillary pressure , permeability (electromagnetism) , core sample , capillary action , mineralogy , residual oil , drainage , trapping , saturation (graph theory) , petroleum reservoir , pore water pressure , multiphase flow , fluid dynamics , petrology , geotechnical engineering , petroleum engineering , porous medium , porosity , core (optical fiber) , mechanics , materials science , chemistry , composite material , ecology , biochemistry , membrane , biology , physics , mathematics , combinatorics
We report the results of an experimental investigation into the multiphase flow properties of CO 2 and water in four distinct sandstone rocks: a Berea sandstone and three reservoir rocks from formations into which CO 2 injection is either currently taking place or is planned. Drainage relative permeability and residual gas saturations were measured at 50°C and 9 MPa pore pressure using the steady state method in a horizontal core flooding apparatus with fluid distributions observed using x‐ray computed tomography. Absolute permeability, capillary pressure curves, and petrological studies were performed on each sample. Relative permeability in the four samples is consistent with general characteristics of drainage in strongly water‐wet rocks. Measurements in the Berea sample are also consistent with past measurements in Berea sandstones using both CO 2 /brine and oil/water fluid systems. Maximum observed saturations and permeabilities are limited by the capillary pressure that can be achieved in the experiment and do not represent endpoint values. It is likely that maximum saturations observed in other studies are limited in the same way and there is no indication that low endpoint relative permeabilities are a characteristic of the CO 2 /water system. Residual trapping in three of the rocks is consistent with trapping in strongly water‐wet systems, and the results from the Berea sample are again consistent with observations in past studies. This confirms that residual trapping can play a major role in the immobilization of CO 2 injected into the subsurface. In the Mt. Simon sandstone, a nonmonotonic relationship between initial and residual CO 2 saturations is indicative of a rock that is mixed or intermediate wet, and further investigations should be performed to establish the wetting properties of illite‐rich rocks. The combined results suggest that the petrophysical properties of the multiphase flow of CO 2 /water through siliciclastic rocks is for the most part typical of a strongly water‐wet system and that analog fluids and conditions may be used to characterize these properties. Further investigation is required to identify the wetting properties of illite‐rich rocks during imbibition processes.