البحث — المستودع الرقمي العراقي

المستخلص: In the oil and gas industry, the crude oil pipelines which made of low carbon steel suffer from internal corrosion. The corrosion operation is originally related with the presence of the wastewater mixed with the crude oil, especially when it is accompanied by hydrogen sulfide, carbon dioxide, elemental sulfur, inorganic salts, organic acids, and bacteria. Corrosion inhibitors injection in the oilfield is a most common and beneficial method for prevention the pipelines internal corrosion. Because of a high cost and toxic nature of the chemical corrosion inhibitors which used presently in oil industry, it is necessary to promote a less expensive and environmentally acceptable inhibitors, natural plants can be treated as a perfect sources for this purpose.This study investigate the internal corrosion of low carbon steel pipelines in fluid environments, as well as prepare and use natural and locally available plant ( the bark of eucalyptus tree) as a natural corrosion inhibitor, and compared the new inhibitor with a chemical inhibitor used by Missan Oil Company (MOC) in terms of the cost, toxicity, availability and performance.Some experiments were achieved to estimate the performance of a new inhibitor, one of these tests include corrosion measurement by simple immersion in crude oil within and without of inhibitors which added in different amounts 30, 40, 50, and 60 ppm , where the best inhibition efficiencies which get when added the inhibitors in a critical amounts or closest to it, since for the aqueous extract (EB - A) the inhibition efficiency reached (94.4) and (86.71)% at 300 and 323K respectively, and for diethyl ether extract (EB - D) reached (82.87) and (84.6)% at 300 and 323K respectively, while the chemical inhibitor (CRW) which used by MOC reach to (84.21) and (88.73)% at 300 and 323K respectively.optical microscopy examination have been conducted to evaluate the corrosion nature where it show a clear difference in the topography of the immersed samples surface after add the inhibitors at two temperatures.Another tests was achieved to evaluate the corrosion behavior such as potentiostatic polarization and open circuit potential tests in wastewater, since the inhibitor efficiency at 313k reached (88.21)% when add a 60ppm from the EB - A inhibitor to the wastewater in Tafel extrapolation, while it reached (74.91)% when add a 30ppm from the EB - D inhibitor.Several tests was achieved such as FT - IR spectra and using a chemical reagents to detection the presence of many active groups and the presence of tannins, phenols and alkaloids in the Eucalyptus Bark (EB).The results show , that the new corrosion inhibitor is not only equivalent to a chemical inhibitor, but have greatly improvement properties such as : high efficiency , low cost , non - toxic , easily to product, and nonpolluting as compared with chemical inhibitor which is considered toxic and cancering inhibitor.