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AuthorAhmed M.E.
AuthorHussein I.A.
AuthorOnawole A.T.
AuthorMahmoud M.
AuthorSaad M.A.
Available date2022-04-25T10:59:42Z
Publication Date2021
Publication NameSPE Production and Operations
ResourceScopus
Identifierhttp://dx.doi.org/10.2118/204478-PA
URIhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85114049892&doi=10.2118%2f204478-PA&partnerID=40&md5=c2df97eaff249da95356b321775aebc3
URIhttp://hdl.handle.net/10576/30375
AbstractIron sulfide scale causes major losses in both upstream and downstream sectors of the hydrocarbon industry. Pyrite is one of the most-difficult forms of iron sulfide scale from a removal point of view. Inorganic acids such as hydrochloric acid (HCl) are not recommended for removing pyrite scales because they have many drawbacks, including low pyrite solubility, high corrosivity to the tubular system, and generation of toxic hydrogen sulfide (H2S). In this work, pyrite-scale dissolution is studied using an ecofriendly formulation of glutamic diacetic acid [L-glutamic acid, N, N-diacetic acid (GLDA)] as an alternative to HCl. Although GLDA has shown potential for removing iron sulfide in general and pyrite scale in particular, still GLDA/pyrite kinetics have not been well-understood. Both experimental and theoretical techniques have been used. The reaction kinetics has been investigated in a rotating-disk apparatus (RDA) at typical reservoir conditions of 150°C and 1,000 psi (Conway et al. 1999). Characterization techniques, including X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM), have been used to study the surface chemistry before and after treatment with GLDA, and the results support pyrite removal. Furthermore, density-functional-theory (DFT) calculations have been performed to understand the ability of GLDA to dissolve iron sulfide scale at the atomistic level. From the laboratory results, the reaction rate using 20-wt% GLDA (pH of 3.8) was 5.378×10−8 mol/cm2·s. The measured rate outperformed other proposed formulations according to the tetrakis(hydroxymethyl)phosphonium sulfate (THPS) formulation by 15 times. In addition, GLDA surpassed the most recent results on diethylenetriamine penta-acetic acid (DTPA) by nearly an order of magnitude. Moreover, pyrite dissolution in GLDA increases as the disk rotational speed increased, which indicates mass-transfer control with a diffusion coefficient of 1.338×10−7 cm2/s. Furthermore, from molecular modeling using DFT, the binding energy between GLDA and Fe2+ is calculated as –105.97 kcal/mol. The negative value observed correlates with the stability constant and indicates the strong binding affinity to Fe2+. Finally, GLDA could be recommended for pyrite-scale removal because it is biodegradable, less corrosive, free of H2S, and achieved solubility that outperformed THPS- and DTPA-based formulations.
SponsorThis publication was made possible by the National Priorities Research Program Grant No. 9-084-2-041 from the Qatar National Research Fund (a member of the Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. Qatar University and the Gas Processing Center are acknowledged for their support. Analyses of iron concentrations were performed in the Central Laboratories Unit at Qatar University. The authors would like to thank Sardar Ali for the helpful discussions regarding the XPS analysis.
Languageen
PublisherSociety of Petroleum Engineers (SPE)
SubjectAmino acids
Binding energy
Chlorine compounds
Density functional theory
Desulfurization
Dissolution
Hydrogen sulfide
Mass transfer
Pyrites
Reaction kinetics
Scanning electron microscopy
Solubility
Sulfide minerals
Sulfur compounds
Surface chemistry
X ray photoelectron spectroscopy
Characterization techniques
Diethylenetriamine penta-acetic acids
Disk rotational speed
Experimental investigations
Mass transfer control
Reservoir conditions
Rotating disk apparatuses (RDA)
Theoretical technique
Hydrochloric acid
chemical compound
concentration (composition)
detection method
experimental study
hydrochloric acid
pollutant removal
pyrite
theoretical study
TitlePyrite-scale removal using glutamic diacetic acid: A theoretical and experimental investigation
TypeArticle
Pagination751-759
Issue Number3
Volume Number36
dc.accessType Abstract Only


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