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AuthorAhmed M.
AuthorHussein I.A.
AuthorOnawole A.T.
AuthorSaad M.A.
AuthorMahmoud M.
Available date2022-04-25T10:59:45Z
Publication Date2020
Publication NameACS Omega
AbstractScale mineral deposition is a critical problem that hinders the daily production of oil and gas fields. Chemical removal of these scales, based on the scale type, is common. In this paper, borax and diethylene tremaine penta acetic (DTPA) acid-based formulations are used for the removal of sulfides, carbonates, and sulfate scales. In particular, the dissolution rates of sulfide (pyrite, pyrrhotite, and galena), sulfate (celestite and barite), and carbonate (calcite) scales were investigated in a rotating disc apparatus at typical well conditions. Scanning electron microscopy–energy-dispersive X-ray and X-ray diffraction analyses were performed for characterizing scale composition and type. The effect of temperature, scale type, and formulation on the dissolution rate is studied. Even though borax formulation has been developed for the sulfide scale removal, it showed a high dissolution rate for the carbonate scale (7.23 × 10–7 mol·L–1·s–1·cm–2). For the sulfide scale, the highest dissolution in borax formulation was obtained with galena (lead sulfide, PbS), followed by pyrrhotite, and the lowest dissolution was reported for pyrite (1.55 × 10–8 mol·L–1·s–1·cm–2). Borax formulation was found to be inefficient in the removal of sulfate scales with a dissolution rate lower than carbonate and sulfide scales by 3 and 2 orders of magnitude, respectively. Similarly, DTPA-based formulation has yielded the highest dissolution for the carbonate scale (7.98 × 10–6 mol·L–1·s–1·cm–2). However, for sulfate, DTPA-based formulation showed better performance than borax. The increase in temperature leads to an increase in the dissolution rate for almost all types of scales; however, DTPA-based formulation showed improved performance with temperature. Both formulations are efficient in removing sulfate- and sulfide-rich scales. The experimental results of DTPA have been validated by density functional theory calculations of binding energies between DTPA and metal ions present in the mixed scale.
SponsorThis work was supported by funding # NPRP9-084-2-041 from Qatar National Research Fund. The outcomes attained herein are exclusively the responsibility of the authors. Qatar University and the Gas Processing Center are acknowledged for their support. Analysis of cation concentrations were done in the Central Laboratories Unit, Qatar University. The authors also would like to acknowledge AkzoNobel for supplying the chelating agent used in this work.
PublisherAmerican Chemical Society
inorganic oilfield scales
green formulations
TitleDissolution kinetics of different inorganic oilfield scales in green formulations
Issue Number46
Volume Number5

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