Development of Ecofriendly Corrosion Inhibitors for Application in Acidization of Petroleum Oil Well

ED Hindawi Publishing Corporation Journal of Chemistry Volume 2013, Article ID 618684, 9 pages http://dx.doi.org/10.1155/2013/618684 Research Article Development of Ecofriendly Corrosion Inhibitors for Application in Acidization of Petroleum Oil Well 1 2 CT M. Yadav,1 Sumit Kumar,1 and P. N. Yadav2 Department of Applied Chemistry, Indian School of Mines, Dhanbad 826004, India Department of Physics Post Graduate College, Ghazipur 233001, India Correspondence should be addressed to M. Yadav; Received 5 June 2012; Revised 25 July 2012; Accepted 30 July 2012 Academic Editor: Nick Kalogeropoulos TR A Copyright © 2013 M. Yadav et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. RE In the present investigation the protective ability of 1-(2-aminoethyl)-2-octadecylimidazoline (AEODI) and 1-(2octadecylamidoethyl)-2-octadecylimidazoline (ODAEODI) as corrosion inhibitors for N80 steel in 15% hydrochloric acid has been studied, which may �nd application as ecofriendly corrosion inhibitors in acidizing processes in petroleum industry. Different concentration of synthesized inhibitors AEODI and ODAEODI was added to test solution (15% HCl), and corrosion inhibition of N80 steel was tested by weight loss, potentiodynamic polarization, and AC impedance measurements. In�uence of temperature (298 to 323 K) on the inhibition behaviour was studied. Surface studies were performed by using SEM. It was found that both the inhibitors were effective inhibitors, and their inhibition e�ciency was signi�cantly increased with increasing their concentration. Polarization curves revealed that the used inhibitors represent mixed-type inhibitors. e adsorption of used inhibitors led to a reduction in the double-layer capacitance and an increase in the charge transfer resistance. e adsorption of used compounds was found to obey Langmuir isotherm. e adsorption of the corrosion inhibitors at the surface of N80 steel is the root cause of corrosion inhibition. 1. Introduction N80 steel is generally used as main construction material for down hole tubular, �ow lines, and transmission pipelines in petroleum industry. e main problem of applying N80 steel is its dissolution in acidic solutions. e acidization of petroleum oil well is one of the important stimulation techniques for enhancing oil production. It is commonly brought about by forcing a solution of 15% to 28% hydrochloric acid into the well to remove plugging in the bore well and stimulate production in petroleum industry. To reduce the aggressive attack of the acid on tubing and casing materials (N80 steel), inhibitors are added to the acid solution during the acidifying process [1]. In the previous work some organic inhibitors have been tested for corrosion inhibition of N80 steel in hydrochloric medium [2–5]. e effective acidizing inhibitors that are usually found in commercial formulations suffer from drawbacks, they are effective only at high concentrations, and they are harmful to the environment due to their toxicity, so it is important to search for new nontoxic and effective organic corrosion inhibitors for N80 steel-15% hydrochloric acid system. Imidazoline derivatives, because of their good solubility, high stability, and lower toxicity, have been widely used [6–8]. e encouraging results obtained with imidazoline derivatives have incited us to synthesize some imidazoline derivatives and extend their use in the corrosion inhibiting action on N80 steel in HCl solution. us, it was considered interesting to synthesize nontoxic imidazoline compounds like 1-(2-aminoethyl)-2-octadecylimidazoline (AEODI) and 1-(2-octadecylamidoethyl)2-octadecylimidazoline (ODAEODI) and to assess their inhibitive properties for oil-well tubular steel (N80) in 15% hydrochloric acid. 2. Experimental 2.1. Materials. Rectangular steel coupons in size of 6.0 × 2.0 × 0.3 cm were cut from the N80 steel casing (supplied by ONGC) with a small hole ≈2 mm diameter at the upper edge of specimen for weight loss studies, and the size of 2 Journal of Chemistry 𝐼𝐼0 − 𝐼𝐼inh × 100, (3) 𝐼𝐼0 where 𝐼𝐼0 is corrosion current in absence of inhibitor and 𝐼𝐼inh is corrosion current in presence of inhibitor. %IE = 2.4. AC Impedance Studies. AC-impedance studies were carried out in a three-electrode cell assembly using computer controlled VoltaLab 10 electrochemical analyser, using N80 steel as the working electrode, platinum as counter electrode, and saturated calomel as reference electrode. e data were analysed using Voltamaster 4.0 soware. e electrochemical impedance spectra (EIS) were acquired in the frequency range from 10 kHz to 1 mHz at the rest potential by applying 10 mV sine wave AC voltage. e charge transfer resistance (𝑅𝑅ct ) and double-layer capacitance (𝐶𝐶dl ) were determined from Nyquist plots. e inhibition efficiencies were calculated from charge transfer resistance values by using the following formula: TR A CT 2.2. Weight Loss Measurements. e inhibitor concentration in weight loss study was in range of 20 to 200 ppm. Volume of test solution was 300 mL. e test coupons were mechanically polished with different grades of emery papers, cleaned with acetone, washed with distilled water, and �nally dried in dry air before every experiment. Aer weighing accurately, the specimens were immersed in 500 mL of 15% HCl with and without the addition of different concentration of inhibitors. Aer 6 hours the coupons were taken out, washed, dried, and weighed accurately. High temperature (30–50∘ C) experiments were also carried out for a period of 6 h using water circulated Ultra thermostat (model NBE, Germany) with an accuracy of ±0.5∘ C. Duplicate experiments were performed in each, and mean value of weight loss was reported. e corrosion inhibition ability of an inhibitor is expressed by weight loss method in terms of inhibitor efficiency and is determined by the percentage decrease in corrosion rate aer inhibition test. Consider curves, Tafel slopes (𝛽𝛽a and 𝛽𝛽c) and corrosion current (𝐼𝐼corr ) were obtained. For calculating %IE by electrochemical polarization method we use the following formula: ED electrode for electrochemical studies was taken as 1.0 × 1.0 × 0.3 cm. N80 steel sample used for the study was analyzed in MET-CHEM Laboratories, Baroda, India and found to have the composition, C (0.31%), S (0.008%), P (0.010%), Si (0.19%), Mn (0.92%), Cr (0.20%), and Fe the rest. e corrosive solution was 15% HCl, obtained by the dilution of hydrochloric acid (Emerk, sp gravity ≈ 1.18) with double distilled water. IE% = 󶀦󶀦 CR0 − CR 󶀶󶀶 × 100, CR0 (1) where CR0 is corrosion rate in absence of inhibitor and CR: corrosion rate in presence of inhibitor. Corrosion rate (CR) for the specimen can be calculated in millimeter penetration per years (mmpy) with the help of the following equation: Corro (...truncated)