Augustine Agi

Natural polymer flow behaviour in porous media for enhanced oil recovery applications: a review

AbstractnWhen a reservoir is flooded with polymer, the mobility ratio between the displaced fluid and the displacing fluid become favourable compared to the conventional water flooding. In the oil and gas industry, the synthetic polymer polyacrylamide in hydrolysed form and the biopolymer xanthan are being used for this purpose. However, the polyacrylamide is susceptible to high temperature and salinity. Also, its synthetic nature makes it harmful to the environment. The biopolymer xanthan has the problem of degradation and both are very expensive. With the shortfall in crude oil price and the high cost of exploitation and drilling new wells, there is need to look inward and think out of the box in formulating new improved polymers that can combat these problems. Natural polymers from agricultural and forest produce are abundant in nature, cheap and environmentally friendly. These agricultural and forest produce contain starch and cellulose which are known to have rigid and long polysaccharide chains that can withstand the harsh reservoir conditions. But the design of a polymer flood or a permeability-modified process involving polymer requires knowledge about the polymer flow mechanism and the rheological behaviour of the porous media. This paper, therefore, reviews the available natural polymers that can be used for enhanced oil recovery applications and the mechanism affecting their flow behaviour in porous media. The emphasis is on the physical aspect of the flow, the microscopic rheological behaviour of the natural polymers. The dominant mechanism of the flow process was adsorption, mechanical entrapment and hydrodynamic retention. It was observed that the polymer exhibited non-Newtonian, pseudoplastic and shear-thinning behaviours. The literature review on oil displacement test indicates that natural polymers can recover additional oil from an oil field. Environmental application issues associated with the application of natural polymers have opened new frontier for research and are also highlighted herein.

Treated Rhizophora mucronata tannin as a corrosion inhibitor in chloride solution

Treated Rhizopora mucronata tannin (RMT) as a corrosion inhibitor for carbon steel and copper in oil and gas facilities was investigated. Corrosion rate of carbon-steel and copper in 3wt% NaCl solution by RMT was studied using chemical (weight loss method) and spectroscopic (FTIR) techniques at various temperatures in the ranges of 26–90°C. The weight loss data was compared to the electrochemical by the application of Faraday’s law for the conversion of corrosion rate data from one system to another. The inhibitive efficiency of RMT was compared with commercial inhibitor sodium benzotriazole (BTA-S). The best concentration of RMT was 20% (w/v), increase in concentration of RMT decreased the corrosion rate and increased the inhibitive efficiency. Increase in temperature increased the corrosion rate and decreased the inhibitive efficiency but, the rate of corrosion was mild with RMT. The FTIR result shows the presence of hydroxyl group, aromatic group, esters and the substituted benzene group indicating the purity of the tannin. The trend of RMT was similar to that of BTA-S, but its inhibitive efficiency for carbon-steel was poor (6%) compared to RMT (59%). BTA-S was efficient for copper (76%) compared to RMT (74%) at 40% (w/v) and 20% (w/v) concentration respectively. RMT was efficient even at low concentration therefore, the use of RMT as a cost effective and environmentally friendly corrosion inhibiting agent for carbon steel and copper is herein proposed.

Ultrasonic Assisted Ultrafiltration Process for Emulsification of Oil Field Produced Water Treatment

Ultrafiltration has been proven to be very effective in the treatment of oil-in-water emulsions, since no chemical additives are required. However, ultrafiltration has its limitations, the main limits are concentration polarization resulting to permeate flux decline with time. Adsorption, accumulation of oil and particles on the membrane surface which causes fouling of the membrane. Studies have shown that the ultrasonic is effective in cleaning of fouled membrane and enhancing membrane filtration performance. But the effectiveness also, depends on the selection of appropriate membrane material, membrane geometry, ultrasonic module design, operational and processing condition. In this study, a hollow and flat-sheet polyurethane (PU) membranes synthesized with different additives and solvent were used and their performance evaluated with oil-in-water emulsion. The steady-state permeate flux and the rejection of oil in percentage (%) at two different modes were determined. A dry/wet spinning technique was used to fabricate the flat-sheet and hollow fibre membrane (HFMs) using Polyethersulfone (PES) polymer base, Polyvinylpyrrolidone (PVP) additive and N, N-Dimethylacetamide (DMAc) solvent. Ultrasonic assisted cross-flow ultrafiltration module was built to avoid loss of ultrasonic to the surrounding. The polyurethane (PU) was synthesized by polymerization and sulphonation to have an anionic group (-OH; -COOH; and -SO3H) on the membrane surface. Changes in morphological properties of the membrane had a significant effect on the permeate flow rate and oil removal. Generation of cavitation and Brownian motion by the ultrasonic were the dominant mechanisms responsible for ultrafiltration by cracking the cake layers and reducing concentration polarization at the membrane surface. The percentage of oil after ultrafiltration process with ultrasonic is about 90% compared to 49% without ultrasonic. Ultrasonic is effective in enhancing the membrane permeate flux and controlling membrane fouling.

Effect of Temperature and Acid Concentration on Rhizophora mucronata Tannin as a Corrosion Inhibitor

AbstractThe effect of temperature and acid concentration on a newly formulated tannin as a corrosion inhibitor for carbon steel in oil and gas facilities was investigated. Corrosion rate of carbon steel in HCl acid solutions (0, 5, 10, 15, 20, 25 and 30%) by Rhizophora mucronata tannin (RMT) was studied using chemical (weight loss method) and spectroscopic (FTIR) techniques at various temperatures in the ranges of 26–70xa0°C. At 20% optimum concentration of acid, the FTIR result showed the presence of hydroxyl group, aromatic group, esters and the substituted benzene group, indicating the purity of the tannin. The increase in HCl acid concentration and temperature increased the corrosion rate, but the rate of corrosion was mild with RMT. Therefore, the use of RMT as a cost-effective and environmental-friendly corrosion-inhibiting agent for carbon steel is herein proposed.n

Mechanism governing nanoparticle flow behaviour in porous media: insight for enhanced oil recovery applications

Nanotechnology has found its way to petroleum engineering, it is well-accepted path in the oil and gas industry to recover more oil trapped in the reservoir. But the addition of nanoparticles to a liquid can result in the simplest flow becoming complex. To understand the working mechanism, there is a need to study the flow behaviour of these particles. This review highlights the mechanism affecting the flow of nanoparticles in porous media as it relates to enhanced oil recovery. The discussion focuses on chemical-enhanced oil recovery, a review on laboratory experiment on wettability alteration, effect of interfacial tension and the stability of emulsion and foam is discussed. The flow behaviour of nanoparticles in porous media was discussed laying emphasis on the physical aspect of the flow, the microscopic rheological behaviour and the adsorption of the nanoparticles. It was observed that nanofluids exhibit Newtonian behaviour at low shear rate and non-Newtonian behaviour at high shear rate. Gravitational and capillary forces are responsible for the shift in wettability from oil-wet to water-wet. The dominant mechanisms of foam flow process were lamellae division and bubble to multiple bubble lamellae division. In a water-wet system, the dominant mechanism of flow process and residual oil mobilization are lamellae division and emulsification, respectively. Whereas in an oil-wet system, the generation of pre-spinning continuous gas foam was the dominant mechanism. The literature review on oil displacement test and field trials indicates that nanoparticles can recover additional oil. The challenges encountered have opened new frontier for research and are highlighted herein.

Magnetite-sporopollenin/graphene oxide as new preconcentration adsorbent for removal of polar organophosphorus pesticides in vegetables

In this study, a new magnetic adsorbent based on magnetite-sporopollenin/graphene oxide (Fe3O4-SP/GO) was successfully developed. The adsorbent was applied for magnetic solid phase extraction (MSPE) of three selected polar organophosphorus pesticides (OPPs), namely, dimethoate, phenthoate, and phosphamidon, prior to gas chromatography analysis with electron capture detection (GC-μECD). The Fe3O4-SP/GO adsorbent combines the advantages of superior adsorption capability of the modified sporopollenin (SP) with graphene oxide (GO) and magnetite (Fe3O4) for easy isolation from sample solution. Several MSPE parameters were optimized. Under optimized conditions, excellent linearity (R2u2009≥u20090.9994) was achieved using matrix match calibration in the range of 0.1 to 500xa0ngxa0mL−1. The limit of detection (LOD) method (S/Nu2009=u20093) was from 0.02 to 0.05xa0ngxa0mL−1. The developed Fe3O4-SP/GO MSPE method was successfully applied for the determination of these three polar OPPs in cucumber, long beans, bell pepper, and tomato samples. Good recoveries (81.0–120.0%) and good relative standard deviation (RSD) (1.4–7.8%, nu2009=u20093) were obtained for the spiked OPPs (1xa0ngxa0mL−1) from real samples. This study is beneficial for adsorptive removal of toxic pesticide compounds from vegetable samples.