Abstract:Preferential injection into high permeability thief zones or fractures can result in early breakthrough at production wells and large unswept areas of high oil saturation, which impact the economic life of a well. A variety of conformance control techniques, including polymer and silica gel treatments, have been designed to block flow through the swept zones. Over a certain range of salinities, silica nanoparticle suspensions form a gel in bulk phase behavior tests. These gels have potential for in situ flow d… Show more
“…For completely solid gels, the gel does not flow on rotating the vials. In a study by Metin et al 24 , it was resulted that two-phase gelation occurs at low silica concentration whereas a single-phase gel is formed at high particle concentration, which is in contrast with the findings of this study. Figure 2 depicts that the single- and two-phase gelation is dependent on the salt concentration, not particle concentration.…”
Section: Resultscontrasting
confidence: 99%
“…This increase is larger at high particle concentration and low salt concentration. The results obtained are similar to those reported previously 24 . Figure 10 Storage modulus (G′) and loss modulus (G″) versus shear strain for different solid gels formed from different concentrations of silica and NaCl in DIW after 24 h. …”
Section: Resultssupporting
confidence: 92%
“…It is observed that at a fixed silica or NaCl concentration, increasing the other parameter concentration would increase the viscosity of final gels, indicating that both silica and NaCl concentrations are determining parameters, which agrees well with the results reported by Metin et al 24 . The addition of only 1 wt% NaCl to the dispersion with 5 wt% silica and 2 wt% NaCl in DIW enhances the viscosity of the final gel dramatically.…”
High water production in oil fields is an area of concern due to economic issues and borehole/wellhead damages. Colloidal gels can be a good alternative to polymers to address this as they can tolerate harsh oil reservoir conditions. A series of bottle tests with different silica and NaCl concentrations were first conducted. The gelation time, cation valence, rheology, and viscosity were investigated to characterize the gels. The applicability of solid gels in porous media was finally inspected in a dual-patterned glass micromodel. Bottle test results showed that increasing NaCl concentration at a constant silica concentration can convert solid gels into two-phase gels and then viscous suspensions. Na+ replacement with Mg2+ resulted a distinctive behaviour probably due to higher coagulating ability of Mg2+. Rheology and viscosity results agreed with gelation times: gel with shortest gelation time had the highest viscosity and storage/loss modulus but was not the most elastic one. Water injection into glass micromodel half-saturated with crude oil and solid gel proved that the gel is strong against pressure gradients applied by injected phase which is promising for water conformance controls. The diverted injected phase recorded an oil recovery of 53% which was not feasible without blocking the water zone.
“…For completely solid gels, the gel does not flow on rotating the vials. In a study by Metin et al 24 , it was resulted that two-phase gelation occurs at low silica concentration whereas a single-phase gel is formed at high particle concentration, which is in contrast with the findings of this study. Figure 2 depicts that the single- and two-phase gelation is dependent on the salt concentration, not particle concentration.…”
Section: Resultscontrasting
confidence: 99%
“…This increase is larger at high particle concentration and low salt concentration. The results obtained are similar to those reported previously 24 . Figure 10 Storage modulus (G′) and loss modulus (G″) versus shear strain for different solid gels formed from different concentrations of silica and NaCl in DIW after 24 h. …”
Section: Resultssupporting
confidence: 92%
“…It is observed that at a fixed silica or NaCl concentration, increasing the other parameter concentration would increase the viscosity of final gels, indicating that both silica and NaCl concentrations are determining parameters, which agrees well with the results reported by Metin et al 24 . The addition of only 1 wt% NaCl to the dispersion with 5 wt% silica and 2 wt% NaCl in DIW enhances the viscosity of the final gel dramatically.…”
High water production in oil fields is an area of concern due to economic issues and borehole/wellhead damages. Colloidal gels can be a good alternative to polymers to address this as they can tolerate harsh oil reservoir conditions. A series of bottle tests with different silica and NaCl concentrations were first conducted. The gelation time, cation valence, rheology, and viscosity were investigated to characterize the gels. The applicability of solid gels in porous media was finally inspected in a dual-patterned glass micromodel. Bottle test results showed that increasing NaCl concentration at a constant silica concentration can convert solid gels into two-phase gels and then viscous suspensions. Na+ replacement with Mg2+ resulted a distinctive behaviour probably due to higher coagulating ability of Mg2+. Rheology and viscosity results agreed with gelation times: gel with shortest gelation time had the highest viscosity and storage/loss modulus but was not the most elastic one. Water injection into glass micromodel half-saturated with crude oil and solid gel proved that the gel is strong against pressure gradients applied by injected phase which is promising for water conformance controls. The diverted injected phase recorded an oil recovery of 53% which was not feasible without blocking the water zone.
“…While several rheological studies of alkoxide-, 49,50 nanoparticle- 51,52 and silicate-based 53-55 gels have been described, compression tests performed on silica hydrogels are scarce.…”
aSilicates-in-silica nanocomposite hydrogels obtained from sodium silicates/colloidal silica mixtures have previously been found to be useful for bacterial encapsulation. However the extension of synthesis conditions and the understanding of their impact on the silica matrix would widen the applicability of this process in terms of encapsulated organisms and the host properties. Here the influence of silicates and the colloidal silica concentration as well as pH conditions on the gel time, the optical properties, the structural and mechanical properties of silica matrices was studied. We show that gel formation is driven by silicate condensation but that the aggregation of silica colloids also has a major influence on the transparency and structure of the nanocomposites. Three different photosynthetic organisms, cyanobacteria Anabaena flos-aquae and two microalgae Chorella vulgaris and Euglena gracilis, were used as probes of the phycocompatibility of the process. The three organisms were highly sensitive to the silicate concentration, which impacts both the gelation time and ionic strength conditions. The Ludox content was crucial for cyanobacteria as it strongly impacts the Young's modulus of the matrices.The detrimental effect of acidic pH on cell suspension was compensated by the silica network. Overall, it is now possible to select optimal encapsulation conditions based on the physiology of the targeted cells, opening wide perspectives for the design of biosensors and bioreactors.
“…An important feature of a rather large group of nanoparticles is their ability to form so-called Pickering emulsions (Ramsden 1903;Pickering 1907;Metin et al 2014). Emulsions are systems composed of two phases-oil and water, where one phase is dispersed in the other, while the stability of such a system is due to the presence of a third component-a stabilizer (emulsifier) (Becher 1957).…”
The
dynamic development of nanotechnology research has contributed to the fact that various types of nanoparticles are increasingly used on a large scale both for medical and biological purposes, but above all in many industrial fields. Such a wide application of nanoparticles is often connected with the need to estimate their characteristic parameters, such as size, size distribution or concentration. Existing instruments are usually quite expensive and not always available. Therefore, other cheaper and simpler methods based on analytical techniques are sought. In this paper, we have proposed a method to estimate the concentration of nanoparticles in solutions based on destabilization analyses of Pickering emulsions produced with their use. The fact of mutual relationship between emulsion concentration, nanoparticle concentration and emulsion stability was used here. The study was carried out using silica nanoparticles. It was presented how to apply the method and what are its limitations. Moreover, an example of its application for the determination of nanoparticle concentration in an unknown sample, obtained after analysis of the permeability of membranes in diffusion chambers, has been presented. The method can become a useful alternative for the determination of nanoparticle concentration in solution in places where no specialized equipment is available.
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