The Effect of DC Electrical Potential on Enhancing Sandstone Reservoir Permeability and Oil Recovery

Abstract

The merits of using electrokinetic phenomena to improve reservoir permeability on sandstone reservoir core plugs are investigated with detail clay mineralogy studies. Normal and reverse DC configuration is applied along with waterflood and studies are conducted on single-phase and two-phase fluid saturation conditions. The produced brines are acid digested and analyzed by inductively coupled plasma mass spectroscopy (ICP-MS). In single-phase flow experiments, permeability enhanced 180% with the normal electrode configuration but negligible change is observed in reverse configuration. In two-phase flow 59% and 10% permeability enhancement is observed in normal and reverse configurations, respectively. In addition, 11.6% additional oil is recovered from normal configuration. The results are examined in terms of electrolyte movement and resulting changes within the clay microstructure. In normal electrode configuration, formation of colloidal clay suspension and flowing out along with produced brine is evident. This has resulted in increased pore passage and core permeability, whereas in the reverse configuration, clay structures remained unchanged. The given explanations are supported by ICP-MS and X-ray diffraction results.     

Performance Analysis of Free Space Optical Networks Using the Beta-Average Recursive Estimator

The present paper aims to investigate and analyze the performance of a point-to-point optical network under a free-space optical (FSO) communication system. Free-space optical communication is a sophisticated technique that has been employed as a channel model of optical wireless communication to transfer large amounts of data at high speeds. However, two important issues, that could affect the source of the FSO link, have been added. The first one is related to chromatic dispersion which is attributed to the chirping phenomenon of the optical signal; the second issue concerns the secondary jamming power that can be generated by some Radio Frequencies from base stations. It is important to note that the effects of atmospheric turbulence, misalignment fading, and atmospheric attenuation as well as geometric losses were also taken into account. The purpose of this research work is to overcome these effects, in order to increase the data transmission rate from 1.25 to 50 Gbps in the proposed system. Consequently, a very efficient solution is suggested to correct these problems and to make the FSO link more reliable using the Beta-Average Recursive Estimator. In addition, the numerical results obtained are presented for the purpose of validating our proposal through the evaluation of the performance of a transmission link in terms of the bit error rate and Q-factor. In the end, the resulting conclusions are listed, explained and discussed.

     

Direct numerical simulation of reactive absorption in gas–liquid flow on structured packing using interface capturing method

Direct numerical simulations are performed in order to study physical and reactive absorption in gas–liquid flow on structured packing. The volume of fluid method is used to capture the gas-liquid interface motion. The mass transport is computed by additional chemical species concentration transport equation with adequate modelling of solubility and chemical reaction. The numerical difficulties arise in imposing jump discontinuity for chemical concentrations at the interface due to different solubility. These difficulties are solved by an original method using a continuum mechanical modelling of two phases flow and Henry's law with constant coefficient. The present study shows how the mass transfer is affected by the complex geometry considered here and by the flow conditions. The results show firstly that the liquid side mass transfer is well predicted by the Higbie theory and the exposure time of a typical element of volume near the interface corresponds to ratio between characteristic length and velocity of the interface provided that the real velocity of the interface is used. For the considered geometry, the transfer is found to be increased compared to the transfer of a plane liquid film. Finally, for the case where the mass transfer is accompanied by second order irreversible chemical reaction in the liquid phase, the numerical results are compared to approximate solution presented by Brian et al. [1961. Penetration theory for gas absorption accompanied by a second order chemical reaction. A.I.Ch.E. J. 7, 226–231] and good agreement is observed.     

Hydroxyapatite starting from calcium carbonate and orthophosphoric acid: synthesis,characterization, and applications

Hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂], Ca-HA, is the emblematic mineral phase of bones, and is known for its complexity and difficult to reproduce chemical synthesis. Among the routes developed for obtaining this calcium phosphate, the so-called double-decomposition method is well described and often utilized. However, the Ca-HA synthesized by this way forms a larger mass of ammonium nitrate by-product than the desired product itself. Pure Ca-HA for orthopedic or dental applications usually uses thermal treatment to eliminate residual nitrogen compounds by releasing them in the atmosphere. Contemporary sol–gel methods currently in fashion produce even more degradation products including solvents and precursor organics. We now report on a green synthesis procedure which makes pure Ca-HA with minimum by-product. The synthesis calls for reacting phosphoric acid with calcium carbonate in water suspension to form a Ca-HA gel of fine particles. This gel can be filtered and the solids recovered, dried, and sintered, but can also be used as-is for environmental applications such as heavy metal ions or textile dye removal from polluted waste streams. This green Ca-HA has been used to trap heavy metals in flue gases and in municipal waste water treatment plants. This low-cost and low-environmental impact material can be developed for medical use because of its absence of impurities, and in catalytic productions for remediation of many environmental problems. Recent results show Ca-HA can also serve in reforming biogas compositions into useful products, after deposition of selected metal elements. Some of these results will be communicated in this paper.     

Design of a composite ethidium-netropsin-anilinoacridine molecule for DNA recognition

Control of gene expression is a cherished goal of cancer chemotherapy. Small ligand molecules able to bind tightly to DNA in a well-defined configuration are being actively searched for. With this goal in mind, we have designed and synthesized the trifunctional molecule R-132, which combines a bispyrrole skeleton for minor groove DNA recognition and two different chromophores, anilinoacridine and ethidium. The affinity and mode of binding of R-132 to DNA were studied by a combination of complementary biochemical and biophysical techniques, which included absorption and fluorescence spectroscopy and circular and linear dichroism. A surface plasmon resonance biosensor analysis was also performed to quantify the kinetic parameters of the drug-DNA interaction process. Altogether, the results demonstrate that the three moieties of the hybrid molecule are engaged in the interaction process, thus validating the rational design strategy. At the biological level, R-132 stabilizes topoisomerase-II-DNA covalent complexes and displays potent cytotoxic activities, which are attributable to its DNA-binding properties. R-132 easily enters and accumulates in cell nuclei, as evidenced by confocal microscopy. R-132 therefore provides a novel lead compound for the design of gene-targeted anticancer agents.     

Efficient numerical solution for highly transient flows

The numerical solutions for different formulations of the conservation equations based on the dependent variables, pressure (P), enthalpy (h), density (ρ), entropy (s) and flow velocity (u) for highly transient flows are presented. The models are each in turn applied for simulating the transient fluid flow dynamics following the rupture of a real and a number of hypothetical pipelines containing liquid, flashing liquid, two-phase and a permanent gas. In the case of the flashing liquid and two-phase pipelines, a significant reduction in the computational run time for the Phu and Psu based simulations as compared to the conventional Pρu formulation is observed. The above effect is found to be much less pronounced for the liquid and permanent gas inventories.     

Dyeing of chrome tanned collagen modified by in situ grafting with 2‐EHA and MAC

The aim of this study deals with the modification of the chrome tanned collagen (leather) by in situ grafting with 2‐ethyl hexyl acrylate (2‐EHA) and methacrylic acid (MAC) to improve its dyeability using Amecid Floxine 2GN (C.I. Acid Red 1) and Remazol Black B (C.I. Reactive Black 5). The optimum condition of in situ grafting has been evaluated. FTIR spectra of the ungrafted and the in situ grafted chrome tanned collagen showed that the corresponding band of the acrylate carbonyl ester occurs at 1730–1735 cm^?1 when compared with the ungrafted ones. The colorimetric data of the in situ grafted and dyed samples exhibited improvement in color shade, dye bath exhaustion, wash and light fastness relative to the ungrafted and dyed ones. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 174–179, 2006     

Preparation and antimicrobial activity of poly (vinyl chloride)/gelatin/montmorillonite biocomposite films

The aim of this study was using a novel antimicrobial thermoplastic plasticizer based on aliphatic anhydride derivative dodecenyl succinic anhydride (DSA) for blending poly (vinyl chloride), PVC, with gelatin in presence of montmorillonite (MMT) using Brabender via polymer melting technique. This anhydride-based plasticizer blended the membrane ingredients homogenously under melting process. The used plasticizer exhibited high performance antimicrobial potency for some biomedical and industrial applications. The prepared biocomposite films were evaluated for antimicrobial activity using agar disc diffusion method against gram-positive and gram-negative bacteria such as: Staphylococcus aureus (S. aureus), Klebsiella pneumonia (K. pneumonia), Bacillus cereus (B. cereus), Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli). The majority of these biocomposites, except the plasticized PVC with DOP, have shown inhibitory effect at different concentrations (1.0–20) mg/ml against all above mentioned bacteria. However, C. albicans and A. niger were the most resistant strains.     

Synthesis and in vitro release study of ibuprofen-loaded gelatin graft copolymer nanoparticles

Objective: This work deals with the preparation, characterization and in vitro release study of IBU-loaded gel graft copolymer nanoparticles.

Method: Gelatin (Gel) graft copolymer nanoparticles were prepared using styrene (Sty) and/or 2-hydroxyethyl methacrylate (HEMA) monomers in the presence of potassium persulfate and glutaraldehyde as an initiator and cross-linker, respectively. The prepared nanoparticles as sustained release drug carriers were investigated using the nonsteriodal anti-inflammatory model drug, ibuprofen (IBU).

Results: The prepared nanoparticles as sustained release drug carriers were investigated using the nonsteriodal anti-inflammatory model drug, IBU. The prepared Gel/HEMA and Gel/Sty nanoparticles exhibited particles size ranging from 15 to 17?nm and from 0.42 to 5?mm, respectively. The dissolution of IBU in phosphate buffer, pH 7.4, at 37°C from the prepared nanoparticles was evaluated using UV spectroscopy. In addition, the prepared nanoparticles were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), transmitting electron microscope (TEM) and zeta potential/particle size analyzer. In vitro dissolution study showed that the dissolution rates of the crosslinked nanoparticles were retarded relative to the uncrosslinked ones. Moreover, the released amount constantly decreases with increasing gluteraldehyde content in the gel nanoparticles.

Conclusion: Crosslinked gel-based graft copolymers exhibited slow IBU release within six hours. Furthermore, results from different characterization techniques such as TEM, particles size and zeta potential measurements confirmed the formation of pH-responsive gel-graft copolymer nanoparticles.