Nano-Texturing of Hydrocarbon Reservoirs with Omniphobic Nanoparticles to Mitigate Liquid Phase Trapping

Gas reservoirs contain substantial amounts of natural gas and, in some cases, associated high API liquid hydrocarbons. Condensation of heavy hydrocarbons, especially in the area closer to the wellbore, occurs as a direct result of the decline in reservoir pressure. This hydrocarbon condensate, and in some cases water, tends to accumulate in the pore space and form a liquid bank. This liquid bank will result in a reduction in gas relative permeability and overall reduction in the well's productivity. This paper illustrates the synthesis and utilization of surface modified silica nanoparticles to mitigate the liquid banking phenomenon in gas reservoirs. Silica nanoparticles (S-NPs), of different sizes, were synthesized using the Stöber process. The impact of the nanoparticle size and degree of functionalization with different hydrophobic and omniphobic groups on altering the rock wettability properties to mitigate liquid banking in gas reservoirs were studied. The S-NPs (of sizes between 50-400 nm) were functionalized with various linear and branched fluoroalkyl groups, terminal amine, and epoxy groups. The particle size of surface modified silica nanoparticles was determined using dynamic light scattering (DLS). The performance of the surface modified silica nanoparticles was evaluated through measuring surface charge, change in contact angle, and by performing core flow experiments at reservoir conditions. A glass slide dip coated with 135 nm surface modified silica nanoparticles solution derivatized with terminal amine and perfluoroalkyl group provided a contact angle of 120° and 83° with water and decane, respectively. The contact angle can be tailored by changing the amount of amine and perfluoroalkyl concentrations on the particle surfaces. A contact angle of around 90° indicates a nonwetting neutral surface that results in minimizing capillary pressure and enhancing mobility of both hydrocarbon and water liquid phases. Using core flow studies and by estimating the improvement in gas and liquid relative permeabilities, surface modified silica nanoparticles treatment demonstrated a comparable performance to commercially available solutions at 1/5 the treatment volume. The surface modified silica nanoparticles sustained its performance indicating a stable and permanent coating on the rock surface. The silica nanoparticles functionalized with fluoroalkyl group, terminal amine and epoxy can be directly pumped without the need for a pretreatment of the rock surface. This results in less complexity when it comes to the field operation. The dual- functionalized silica nanoparticles were found to be effective in changing the rock surface wettability to neutral or nonwetting, thereby providing a potential solution to liquid banking problem in gas reservoirs.

Rapid Microwave-Assisted Synthesis of Organo-Modified Nanostructured Silica Coatings with Tunable Water-Repellence Properties

A simple method to fabricate organo-modified silane coatings for water-repellent surface modification was proposed, by using a microwave sol-gel synthesis of hybrid materials. Low-cost fluorine-free tetraethoxysilane (TEOS) and dodecyltriethoxysilane (DDTES) were used as silane derivatives. The organo-modified silica coatings were prepared by the drop-casting method and were characterized by UV-VIS, FTIR spectroscopy, and AFM and SEM microscopy. The morphology of the film show the existence of submicrometer scale roughness due to the aggregation of modified silica nanoparticles. Contact angles of water and diiodomethane on surfaces modified with as prepared nanostructured film were determined in order to assess the hydrophobic and oleophobic properties. The TEOS/DDTES ratio was proved to be a crucial factor in tuning the wettability properties. The results suggest that significant increase of hydrophobicity could be achieved by using non-fluorinated cost-effective silica nanomaterials produced with a rapid ecofriendly method.

Strong Interaction Between Thiol and Silver Modified Silica Nanoparticles in the SERS Sensing of Municipal Solid Waste and Tannery Waste Leachate From Groundwater

A novel surface enhanced Raman spectroscopy (SERS) based polyvinylthiol (PVASH) and silver modified silica nanoparticles (PSA NPs) was prepared to actively concentrate different types of landfill leachate in water. PSA NPs were characterized with UV-visible spectroscopy, XRD, TEM and EDX. SERS sensitivity of the PSA NPs was proved with environmentally ignored leachate from municipal solid waste (MSW) landfill. The result shows that, SERS sensing of PSA NPs were improved with the presence of thiol group. Further, PSA NPs exhibited similar vibrational bands of MSW and tannery waste (TW) landfill leachate in their nearest homeland aquifers. Hence, this study provides a novel SERS sensor of PSA NPs in the tile to detect and analyze the environmentally ignored organic and inorganic compounds.

Synthesis, Characterization and Biomedical Applications of p(HEMA-co-APTMACI) Hydrogels Crosslinked with Modified Silica Nanoparticles

In this study, a new silica-based crosslinker was successfully synthesized with the reaction between silica nanoparticles modified with amino groups and glycidyl methacrylate (GMA). Using the synthesized silica-based crosslinker, p(HEMA) and p(HEMA-co-APTMACI) hydrogels were synthesized for use as drug carrier systems with the free radical polymerization method. The synthesized silica-based crosslinker and hydrogels were characterized using scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FTIR) devices. The swelling behavior of hydrogels cross-linked with silica was investigated in different physiological media. The hydrogels were loaded with sodium diclofenac (NaDc) as a model drug. Drug release studies from the obtained drug-loaded hydrogels were performed at 37°C in PBS (pH 7.0) media. Additionally, the antibacterial properties of the hydrogels synthesized in the study were investigated against E. coli (gram-negative), B. subtilis, and S. aureus (gram-positive) bacteria using the disk diffusion method. At the end of the study, p(HEMA-co-APTMACI) hydrogels were determined to display a better drug release profile than p(HEMA) hydrogels.