ef9b03432_si_001.pdf (620.28 kB)
Modifying the Wettability of Sandstones Using Nonfluorinated Silylation: To Minimize the Water Blockage Effect
Version 2 2020-01-16, 18:35
Version 1 2019-12-23, 21:44
journal contribution
posted on 2020-01-16, 18:35 authored by Eghan Arjomand, Matthew Myers, Nasser Mohammed Al Hinai, Colin D. Wood, Ali SaeediMultiphase fluid flow characteristics of a reservoir
rock, such
as capillary pressure, displacement efficiency, relative permeability,
and saturation distribution are substantially influenced by the wettability
state of the rock. Being able to change the affinity of the rock toward
different fluid phases present in the formation has implications in
various petroleum applications (e.g., CO2 geo-sequestration,
EOR, gas production). In this study, silylation of sandstone core
samples using nonfluorinated compounds is accomplished using supercritical
CO2 as a solvent and carrier. This approach is cost-effective
and less environmentally sensitive compared to other approaches which
use fluorinated silylation reagents. By using small molecules to only
change the wettability characteristics of core samples without altering
other parameters (e.g., rock pore structure) noticeably, the effects
of wettability alteration alone on multiphase flow (i.e., relative
permeability) can be identified. Spontaneous imbibition tests were
conducted on Gray Berea sandstone before and after silylation treatment,
which showed a diminished rate of water uptake in the post-treatment
sample. The wettability alteration caused by this functionalization
and its impact on multiphase flow characteristics were analyzed using
core flooding tests. The experimental results show that supercritical
CO2-based (scCO2-based) silylation changes the
wettability of the formation from strongly water-wet to intermediate
gas-wet. Core flooding tests showed that the effective permeability
for the water phase was significantly increased, resulting in higher
water removal from the rock matrix. Furthermore, the relative permeability
for the gas phase (in this study, CO2) at residual water
saturation is higher after treatment. Such an outcome confirms that
the change in wettability could be beneficial in geological CO2 storage as well as gas production.