Abstract:In view of enhanced oil recovery, the adsorption behavior of surfactants is usually monitored on smooth model rock surfaces using quartz crystal microbalance with dissipation (QCM-D). However, this is an impractical situation as the effect of the surface roughness of reservoir rocks and its role in surfactant adsorption processes are not yet completely understood. The coupling of electrochemical techniques and QCM-D in one analysis setup (EQCM-D) provides a new methodology to explore complex surfactant adsorpt… Show more
“…To this aim, the last decade or so has witnessed many types of in situ or post-modification methods having been developed to tune the surface polarity, hydrophilicity, oleophobicity, stability, and reactivity of CaCO 3 MNPs. 33,34 CaCO 3 MNPs with distinct surface properties can thus be obtained and used to produce CaCO 3 -based or CaCO 3incorporated structured materials that have growing potential and applications in biomaterials and biomedicines, and environmental applications. 35,36 It has been well established that CaCO 3 particles are stable at pH 7, whereas they dissolve and release carbon dioxide (CO 2 ) gas under acidic conditions, 37 allowing them to be functionalized with targeting molecules or polymers for targeted pH-responsive drug/gene/protein delivery.…”
Various new strategies have been recently developed to produce CaCO3 micro-/nanoparticles with controlled size, morphology, polymorphism and crystallinity, which are then surface modified, functionalized and hierarchically assembled to yield medical, environmental, and energy materials.
“…To this aim, the last decade or so has witnessed many types of in situ or post-modification methods having been developed to tune the surface polarity, hydrophilicity, oleophobicity, stability, and reactivity of CaCO 3 MNPs. 33,34 CaCO 3 MNPs with distinct surface properties can thus be obtained and used to produce CaCO 3 -based or CaCO 3incorporated structured materials that have growing potential and applications in biomaterials and biomedicines, and environmental applications. 35,36 It has been well established that CaCO 3 particles are stable at pH 7, whereas they dissolve and release carbon dioxide (CO 2 ) gas under acidic conditions, 37 allowing them to be functionalized with targeting molecules or polymers for targeted pH-responsive drug/gene/protein delivery.…”
Various new strategies have been recently developed to produce CaCO3 micro-/nanoparticles with controlled size, morphology, polymorphism and crystallinity, which are then surface modified, functionalized and hierarchically assembled to yield medical, environmental, and energy materials.
“…46,47 For example, atomic force microscope (AFM) has considerably contributed to better understanding of dimensions, morphologies, and orientations of adsorbed surfactant layers. [48][49][50][51][52] More recently, quartz crystal microbalance with dissipation monitoring (QCM-D) has been applied to investigate the adsorption behavior of surfactants, [53][54][55][56][57][58][59][60][61][62] which can be also coupled with AFM, spectroscopic ellipsometry (SE), and surface plasmon resonance (SPR) techniques. 52,[63][64][65][66] Therefore, to realize effective transport of surfactants into reservoirs, it is of great importance to understand surfactant adsorption on mineral surfaces.…”
“…This reduced adsorption in SS-1 may be attributed to stronger electrochemical repulsion between the hydrophilic heads of the surfactant molecules and the negatively charged quartz minerals, which constitute ∼40% of the rock minerals. 51 Nonionic surfactants, lacking surface charges, rely on van der Waals forces and hydrogen bonding for adsorption, potentially explaining the higher adsorption observed in SS-3. 20 4.1.4.…”
Adding chemical additives such as surfactants and nanoparticles
to the fracturing fluid is a common field practice for enhanced water
and oil recovery. However, measuring the multiphase permeability of
ultratight rocks is challenging, due to the extremely long time required
to reach flow rate and pressure equilibration. This paper aims at
understanding the effects of surfactant polarity on regained permeability
of tight-rock samples, as functions of reservoir brine salinity and
rock mineralogy, by utilizing a modified core-flooding device. We
propose a laboratory protocol to screen different surfactants used
in hydraulic fracturing operations to reduce interfacial tension (IFT)
and alter wettability from oil-wet to water-wet conditions. The effects
of different surfactants on the relative permeability shift of rock
samples are also investigated. We used tight-core plugs from the Montney
Formation and surfactants with different polarities for conducting
experiments. First, we measured the physical properties of surfactant
solutions, including surface tension, IFT, viscosity, and particle
size. Then, we assessed the effectiveness of different surfactants
for wettability alteration and quantify their adsorption on the rock
surface. Next, we simulated the leak-off, soaking, and flowback processes
under reservoir conditions using a modified core-flooding apparatus
designed for ultralow permeability samples. The results show that,
for Montney cores, although nonionic surfactants show higher adsorption,
their regained liquid permeability (k
L) is relatively higher, compared with anionic surfactants. The measured
regained k
L for nonionic and anionic surfactants
were equal to the initial permeability before the leak-off stage,
suggesting that the surfactant adsorption was not detrimental to the
surfactant’s functionality in maintaining the rock permeability.
This phenomenon suggests that adsorption of some surfactants may be
reversible. However, all the anionic surfactants reduced the regained k
L. The results show that if a reservoir is at
subirreducible water saturation conditions, the leak-off of surfactant
solutions may reduce the regained permeability by increasing the water
saturation near the fracture face after leak-off and flowback processes.
Combining the effects of IFT and wettability alterations in the dimensionless
parameter of capillary number (N
ca) shows
that, above a threshold N
ca value, the
regained permeability remains unchanged, indicating no fracture-face
damage.
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