Structure and stoichiometry of mixed divalent metal (Ca2+/Mg2+/Sr2+/Ba2+) phosphonate scale inhibitor complexes for application in precipitation squeeze processes

S. S. Shaw, K. S. Sorbie

Research output: Contribution to conferencePaper

Abstract

In oilfield applications, various divalent cations are present in field produced waters, e.g. Ca<sup>2+</sup>, Mg<sup>2+</sup>, Sr<sup>2+</sup> and Ba<sup>2+</sup>. The interaction of these cations with phosphonate scale inhibitors (SI) is important both for scale inhibition and inhibitor retention mechanisms. In this paper, the properties of precipitated "mixed" Ca<sup>2+</sup>/M<sup>2+</sup> phosphonate SI complexes formed by 9 common phosphonate species are investigated, where M<sup>2+</sup> may be Mg<sup>2+</sup>, Sr<sup>2+</sup>, or Ba<sup>2+</sup>. These 2 and 3 metal ion complexes with SI are of the form SI-Ca<inf>N1</inf>-Sr<inf>N2</inf> and SI-Ca<inf>N1</inf>-Mg<inf>N2</inf>-Ba<inf>N3</inf>, where the stoichiometry N<inf>1</inf>, N<inf>2</inf> and N<inf>3</inf>, are the respective (M<sup>2+</sup>/SI) molar ratios. Static precipitation tests were performed varying the amounts of Ca<sup>2+</sup> and M<sup>2+</sup> present in the system (at a constant ionic strength), at 95°C, pH 8.5, and fixed [SI]= 2,000ppm. The stoichiometries of the solid precipitates were determined by re-dissolving the precipitated deposits in acidified distilled water (DW/HCl), and then assaying for Ca<sup>2+</sup>, M<sup>2+</sup>, and P directly, under each test condition, by Inductively Coupled Plasma (ICP) spectroscopy. It is shown experimentally that, for all 9 phosphonates tested, these stoichiometries depend on the number of M<sup>2+</sup> binding sites per molecule, solution pH, the relative SI binding constants to Ca<sup>2+</sup> and M<sup>2+</sup> at the test pH, and the solution molar ratio of M<sup>2+</sup>/Ca<sup>2+</sup>.

Original languageEnglish
Publication statusPublished - Jan 2015
EventCorrosion 2015 - Dallas, United States
Duration: 15 Mar 201519 Mar 2015

Conference

ConferenceCorrosion 2015
CountryUnited States
CityDallas
Period15/03/1519/03/15

Fingerprint

Organophosphonates
Stoichiometry
Metals
Positive ions
Inductively coupled plasma
Binding sites
Ionic strength
Metal ions
Precipitates
Divalent Cations
Deposits
Spectroscopy
Cations
Molecules
Binding Sites
Water

Keywords

  • Scale inhibitor phosphonate complexes calcium magnesium strontium barium binding precipitation stoichiometry

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)
  • Materials Science(all)

Cite this

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title = "Structure and stoichiometry of mixed divalent metal (Ca2+/Mg2+/Sr2+/Ba2+) phosphonate scale inhibitor complexes for application in precipitation squeeze processes",
abstract = "In oilfield applications, various divalent cations are present in field produced waters, e.g. Ca2+, Mg2+, Sr2+ and Ba2+. The interaction of these cations with phosphonate scale inhibitors (SI) is important both for scale inhibition and inhibitor retention mechanisms. In this paper, the properties of precipitated {"}mixed{"} Ca2+/M2+ phosphonate SI complexes formed by 9 common phosphonate species are investigated, where M2+ may be Mg2+, Sr2+, or Ba2+. These 2 and 3 metal ion complexes with SI are of the form SI-CaN1-SrN2 and SI-CaN1-MgN2-BaN3, where the stoichiometry N1, N2 and N3, are the respective (M2+/SI) molar ratios. Static precipitation tests were performed varying the amounts of Ca2+ and M2+ present in the system (at a constant ionic strength), at 95°C, pH 8.5, and fixed [SI]= 2,000ppm. The stoichiometries of the solid precipitates were determined by re-dissolving the precipitated deposits in acidified distilled water (DW/HCl), and then assaying for Ca2+, M2+, and P directly, under each test condition, by Inductively Coupled Plasma (ICP) spectroscopy. It is shown experimentally that, for all 9 phosphonates tested, these stoichiometries depend on the number of M2+ binding sites per molecule, solution pH, the relative SI binding constants to Ca2+ and M2+ at the test pH, and the solution molar ratio of M2+/Ca2+.",
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author = "Shaw, {S. S.} and Sorbie, {K. S.}",
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note = "Corrosion 2015 ; Conference date: 15-03-2015 Through 19-03-2015",

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Structure and stoichiometry of mixed divalent metal (Ca2+/Mg2+/Sr2+/Ba2+) phosphonate scale inhibitor complexes for application in precipitation squeeze processes. / Shaw, S. S.; Sorbie, K. S.

2015. Paper presented at Corrosion 2015, Dallas, United States.

Research output: Contribution to conferencePaper

TY - CONF

T1 - Structure and stoichiometry of mixed divalent metal (Ca2+/Mg2+/Sr2+/Ba2+) phosphonate scale inhibitor complexes for application in precipitation squeeze processes

AU - Shaw, S. S.

AU - Sorbie, K. S.

PY - 2015/1

Y1 - 2015/1

N2 - In oilfield applications, various divalent cations are present in field produced waters, e.g. Ca2+, Mg2+, Sr2+ and Ba2+. The interaction of these cations with phosphonate scale inhibitors (SI) is important both for scale inhibition and inhibitor retention mechanisms. In this paper, the properties of precipitated "mixed" Ca2+/M2+ phosphonate SI complexes formed by 9 common phosphonate species are investigated, where M2+ may be Mg2+, Sr2+, or Ba2+. These 2 and 3 metal ion complexes with SI are of the form SI-CaN1-SrN2 and SI-CaN1-MgN2-BaN3, where the stoichiometry N1, N2 and N3, are the respective (M2+/SI) molar ratios. Static precipitation tests were performed varying the amounts of Ca2+ and M2+ present in the system (at a constant ionic strength), at 95°C, pH 8.5, and fixed [SI]= 2,000ppm. The stoichiometries of the solid precipitates were determined by re-dissolving the precipitated deposits in acidified distilled water (DW/HCl), and then assaying for Ca2+, M2+, and P directly, under each test condition, by Inductively Coupled Plasma (ICP) spectroscopy. It is shown experimentally that, for all 9 phosphonates tested, these stoichiometries depend on the number of M2+ binding sites per molecule, solution pH, the relative SI binding constants to Ca2+ and M2+ at the test pH, and the solution molar ratio of M2+/Ca2+.

AB - In oilfield applications, various divalent cations are present in field produced waters, e.g. Ca2+, Mg2+, Sr2+ and Ba2+. The interaction of these cations with phosphonate scale inhibitors (SI) is important both for scale inhibition and inhibitor retention mechanisms. In this paper, the properties of precipitated "mixed" Ca2+/M2+ phosphonate SI complexes formed by 9 common phosphonate species are investigated, where M2+ may be Mg2+, Sr2+, or Ba2+. These 2 and 3 metal ion complexes with SI are of the form SI-CaN1-SrN2 and SI-CaN1-MgN2-BaN3, where the stoichiometry N1, N2 and N3, are the respective (M2+/SI) molar ratios. Static precipitation tests were performed varying the amounts of Ca2+ and M2+ present in the system (at a constant ionic strength), at 95°C, pH 8.5, and fixed [SI]= 2,000ppm. The stoichiometries of the solid precipitates were determined by re-dissolving the precipitated deposits in acidified distilled water (DW/HCl), and then assaying for Ca2+, M2+, and P directly, under each test condition, by Inductively Coupled Plasma (ICP) spectroscopy. It is shown experimentally that, for all 9 phosphonates tested, these stoichiometries depend on the number of M2+ binding sites per molecule, solution pH, the relative SI binding constants to Ca2+ and M2+ at the test pH, and the solution molar ratio of M2+/Ca2+.

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