Browsing by Author "Hethnawi, Afif"

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    Enhanced Oil Recovery from Austin Chalk Carbonate Reservoirs Using Faujasite-Based Nanoparticles Combined with Low-Salinity Water Flooding
    (Energy & Fuels, 2020) Taleb, Moussa; Sagala, Farad; Hethnawi, Afif; Nassar, Nashaat N.
    Recently, the application of nanoparticles for enhancing oil recovery (EOR) in carbonate reservoirs has received great attention from various researchers across the oil and gas industry. In contrast to sandstone reservoirs, carbonates are naturally neutral wet or preferentially oil wet and, therefore, the recovery of oil from these reservoirs by waterflooding techniques is relatively low and inefficient. Hence, the addition of chemical agents can modify rock wettability and increase the efficiency of the waterflooding process. The role of nanoparticles and their implementations in the field of oil recovery has been highlighted by many researchers in the past, due to their attractive features and characteristics. However, choosing the appropriate nanoparticles is not the only limiting factor to guarantee better performance in EOR but also depends on their stability and dispersion under aqueous conditions. Accordingly, many metal oxides or silicate-based nanomaterials have been subjected to surface modifications, following some complex and costly ineffective functionalization steps before their application. In this study, novel and stable nanomaterials of faujasite were synthesized at mild conditions without following any surface modification steps to alter the wettability of Austin Chalk carbonate rocks from oil wet to strongly water wet in the presence of low-salinity water (LSW). The synthesized nanoparticles were well characterized by scanning electron microscopy (SEM), transfer electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and ζ potential to confirm their surface identity, functionality, morphology, and stability. The prepared nanofluids from the synthesized nanoparticles were tested in comparison to brine for their EOR efficiency in carbonate cores. The EOR performance was investigated by interfacial tension (IFT), contact angle, spontaneous imbibition, and displacement tests. The results showed that, compared to formation brine and LSW, the formulated nanofluid could notably alter the rock wettability from strong oil wet to strong water wet. To confirm this, a core-flooding test was performed, which further reiterated the capability of these nanofluids as effective EOR agents in hydrocarbon carbonate reservoirs by recovering an additional 9.6% of OOIP. Consequently, on the basis of the obtained findings, these faujasite-based nanofluids provide a prospect of being applied in EOR in carbonate formations.
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    Hydroxyl-functionalized Silicate-based Nanofluids for Enhanced Oil Recovery
    (Fuel, 2020) Sagala, Farad; Hethnawi, Afif; Nassar, Nashaat N.
    During the production life of the reservoir, wettability alteration from an oil-wet to a strongly water-wet condition and/or lowering the interfacial tension (IFT) between the water and oil phases is required at various stages to enhance oil recovery (EOR). Several chemical agents as potential wettability modifiers (e.g., surfactants and polymers) have been regarded and widely used in oil-wet systems. Recently, various nano-fluids, prepared by dispersing nanoparticles in brine solutions or solvents, have attracted attention as injecting fluid due to their unique properties. A large number of nanoparticles are being investigated for EOR applications either as stand-alone or in combination with surfactants and/or polymers. Because of its stability in brine even at low concentrations, totally or partially hydroxyl-functionalized nano-pyroxenes are capable of recovering additional oil after water flooding. However, the influence of their concentration on various parameters has not been previously investigated. Thus, in this study, we investigated the influence of nano-pyroxene on wettability, IFT and asphaltene aggregation. Wettability measurements were performed by contact angle measurements, imbibition experiments and wettability index to understand the underlying mechanisms. The interaction between nanopyroxene and asphaltene size distribution was investigated as a function of nanopyroxene concentration by dynamic light scattering (DLS) measurements. Results from the IFT measurements, contact angle, imbibition experiments and core flooding tests confirm that nanopyroxene affects oil recovery. Contact angle and wettability index measurements confirmed that adsorption of the nanoparticles on the rock surfaces alters the wettability from intermediate wet to stronger water-wet in the absence and presence of initial water films. In the presence of irreducible water saturation during wettability index measurements, depending on the brine composition and pH, initial alteration with aging resulted in a mixed or intermediate wet that changed to stronger water-wet as the nanopyroxene concentration increased. Moreover, increasing the concentration of nanopyroxene resulted in a noticeable IFT reduction but not an ultra-low range that can remobilize trapped oil due to higher capillary forces. Core flooding tests indicated that nanopyroxene-based nanofluid injection offers ~12–14.5% additional oil in addition to waterflooding.
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    Integrating Silicate-based Nanoparticles with Low Salinity Water Flooding for Enhanced Oil Recovery in Sandstone Reservoirs
    (Industrial & Engineering Chemistry Research, 2020) Sagala, Farad; Hethnawi, Afif; Nassar, Nashaat N.
    A large number of researchers have endeavored to delineate the effects of injecting brine with a low ionic strength in oil reservoirs in the past decade. However, we still cannot conclude the overriding mechanism(s) of recovering oil from this technique. Even with a detailed review of the literature, the effect of low-salinity water flooding (LSWF) shows that a bewildering array of conflicting results have been reported. From the physicochemical point of view, understanding how brine and oil chemistry affects oil recovery helps to optimize recovery from such processes. Furthermore, the use of brine with low ionic strength coupled with nanoparticles during enhanced oil recovery (EOR), especially in the presence of monovalent ions and/or divalent cations, presents a new field of study that requires further investigations. Herein, the main objective of this study was to investigate the fluid/rock interactions at different salinities in the presence of various surface-modified pyroxene nanoparticles. Pyroxene was surface modified using polyethylene amine (PEI), poly(ethylene oxide) (PEO), and triethoxyoctylsilane (TOS). Surface charge, wettability measurements in the presence of various ions in the irreducible water, and core flooding experiments have been conducted to understand the underlying mechanism(s). The surface charge was evaluated by zeta potential measurements, and wettability was determined by the contact angle, imbibition, and relative permeability measurements. Sandstone outcrops and three oil samples with different composition were used. The results show that adding 0.005 wt % nanoparticles to brine with low ionic strength (1000 ppm) can improve the nanofluid stability and EOR. Additionally, in the presence of LSWF combined with nanoparticles, the thickness of the double layer on the rock surface greatly expands, thus increasing the magnitude of zeta potential compared to LSWF alone. The contact angle in the presence of LSW alone and N-PEO, N-PEI, and N-TOS nanofluids was measured as 94 ± 3, 118 ± 3, 112 ± 3, and 130° ± 3°, respectively, conforming wettability alteration from oil/neutral wet to stronger water-wet. Moreover, the greater repulsive force due to double-layer expansion creates a significant shift in the relative permeability curve to the right. Consequently, this results in improved oil recovery by about 15% of the oil originally in place. Based on the obtained findings, LSWF coupled with nanoparticles provides a prospect of being applied in EOR.