Abstract
Scale deposition is a pertinent challenge in the oil and gas industry. Scales formed from iron sulfide are one of the troublous scales, particularly pyrite. Moreover, the use of biodegradable environmentally friendly chemicals reduces the cost compared to the conventional removal process. In this work, the chelating abilities of four novel chemicals, designed using the in silico technique of density functional theory (DFT), are studied as potential iron sulfide scale removers. Only one of the chemicals containing a hydroxamate functional group had a good chelating ability with Fe2+. The chelating strength and ecotoxicological properties of this chemical were compared to diethylenetriaminepentaacetic acid (DTPA), an already established iron sulfide scale remover. The new promising chemical surpassed DTPA in being a safer chemical and having a greater binding affinity to Fe2+ upon optimization, hence, a better choice. The presence of oxime (-NHOH) and carbonyl (C=O) moieties in the new chemical showed that the bidentate form of chelation is favored. Moreover, the presence of an intramolecular hydrogen bond enhanced its chelating ability.
Highlights
Scale deposition is a cogent problem facing oil and gas production
Upon optimization of BOEN by binding it to two Fe2+ ions and adding five explicit water molecules, its binding affinity increased to −340.947 kcal/mol which is higher when Diethylenetriaminepentaacetic acid (DTPA) is complexed with two Fe2+ ions. e ecotoxicological properties of both DTPA and BOEN were compared with the latter safer to use than the former
In both binding affinity and toxicity, BOEN is predicted to be a better choice than DTPA
Summary
Scale deposition is a cogent problem facing oil and gas production. Conventional treatments used in iron sulfide scale removal include chemical and mechanical treatments [7]. The former is preferred over the latter as mechanical treatment frequently exacerbates the situation by leading to more corrosion. Chemical treatments involving the use of hydrochloric acid increase the corrosion rate and produce toxic hydrogen sulfide as a by-product. Chelators have been suggested as a better chemical solution for scale removal [8,9,10,11,12]. Diethylenetriaminepentaacetic acid (DTPA) is one of the effective chelators used for iron sulfide scale removal [1, 2]. In this work, we design novel chemicals based on the hydroxamate functional group and the carboxylic functional group present in DTPA
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