Dual chelant mechanism for the deployment of scale inhibitors in controlled solubility/precipitation treatments

M.J. Todd, J. Savian, Kenneth Stuart Sorbie

    Research output: Contribution to conferencePaper

    Abstract

    In scale inhibitor squeeze treatments, precipitation of the inhibitor within the formation can lead to extended squeeze lifetimes. However, such processes also have the potential to cause formation damage unless they are carefully designed and controlled. The formation of a partially soluble inhibitor/metal complex within a reservoir is the objective for almost all precipitation squeeze packages. However, historically there are numerous ways this is achieved almost all of which require a limited operational window to be deployed successfully. In this paper, we describe the development of a novel dual chelant system which provides a method for controlling both the “wanted” and “unwanted” precipitation of the scale inhibitor package within the formation. The highly tunable nature of the system allows for ease of pumping at more extreme conditions (higher and low temperatures, calcium levels etc.) than have previously been possible. By using the dual chelant mechanism described in this paper, a package can be tuned to precipitate within a certain time frame both at low and high temperatures in brines with varying degrees of salinity and hardness. The scale inhibitor (SI) itself is a chelant or ligand for divalent ions present (mainly Ca2+) and this is denoted L2 and the second chelant, L1, is added to the system at certain design concentrations, as explained in the paper.

    In many situations, the high divalent metal ion content of a produced brine, or formation water can limit the successful pumping of a scale inhibitor due to high levels of calcium, for example. Under these conditions the dual chelant mechanism can also be deployed to prevent scale inhibitor phase separation.

    This paper discloses the theory of how the dual chelant mechanism works using computer modeling and the subsequent confirmation of the simulations by laboratory testing. The importance of the pKa of the SI (L2) and the added chelant, L1, and the relative metal binding constant interactions between L1/ L2 and Ca2+ are explained and investigated. The comparison of the dual chelant mechanism versus conventional packages is demonstrated by core flood experiments. The dual chelant mechanism gives a clear improvement in squeeze lifetime and controllability and provides a platform for the development of many types of controlled solubility scale inhibitor treatment.
    Original languageEnglish
    Pages1-14
    Number of pages14
    DOIs
    Publication statusPublished - May 2012
    EventSPE International Conference on Oilfield Scale - Aberdeen, United Kingdom
    Duration: 30 May 201231 May 2012

    Conference

    ConferenceSPE International Conference on Oilfield Scale
    CountryUnited Kingdom
    CityAberdeen
    Period30/05/1231/05/12

    Fingerprint

    Solubility
    Calcium
    Brines
    Coordination Complexes
    Controllability
    Phase separation
    Metal ions
    Precipitates
    Metals
    Hardness
    Ions
    Ligands
    Temperature
    Water
    Testing
    Experiments
    brine

    Cite this

    Todd, M. J., Savian, J., & Sorbie, K. S. (2012). Dual chelant mechanism for the deployment of scale inhibitors in controlled solubility/precipitation treatments. 1-14. Paper presented at SPE International Conference on Oilfield Scale, Aberdeen, United Kingdom. https://doi.org/10.2118/152870-MS
    Todd, M.J. ; Savian, J. ; Sorbie, Kenneth Stuart. / Dual chelant mechanism for the deployment of scale inhibitors in controlled solubility/precipitation treatments. Paper presented at SPE International Conference on Oilfield Scale, Aberdeen, United Kingdom.14 p.
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    abstract = "In scale inhibitor squeeze treatments, precipitation of the inhibitor within the formation can lead to extended squeeze lifetimes. However, such processes also have the potential to cause formation damage unless they are carefully designed and controlled. The formation of a partially soluble inhibitor/metal complex within a reservoir is the objective for almost all precipitation squeeze packages. However, historically there are numerous ways this is achieved almost all of which require a limited operational window to be deployed successfully. In this paper, we describe the development of a novel dual chelant system which provides a method for controlling both the “wanted” and “unwanted” precipitation of the scale inhibitor package within the formation. The highly tunable nature of the system allows for ease of pumping at more extreme conditions (higher and low temperatures, calcium levels etc.) than have previously been possible. By using the dual chelant mechanism described in this paper, a package can be tuned to precipitate within a certain time frame both at low and high temperatures in brines with varying degrees of salinity and hardness. The scale inhibitor (SI) itself is a chelant or ligand for divalent ions present (mainly Ca2+) and this is denoted L2 and the second chelant, L1, is added to the system at certain design concentrations, as explained in the paper. In many situations, the high divalent metal ion content of a produced brine, or formation water can limit the successful pumping of a scale inhibitor due to high levels of calcium, for example. Under these conditions the dual chelant mechanism can also be deployed to prevent scale inhibitor phase separation. This paper discloses the theory of how the dual chelant mechanism works using computer modeling and the subsequent confirmation of the simulations by laboratory testing. The importance of the pKa of the SI (L2) and the added chelant, L1, and the relative metal binding constant interactions between L1/ L2 and Ca2+ are explained and investigated. The comparison of the dual chelant mechanism versus conventional packages is demonstrated by core flood experiments. The dual chelant mechanism gives a clear improvement in squeeze lifetime and controllability and provides a platform for the development of many types of controlled solubility scale inhibitor treatment.",
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    Todd, MJ, Savian, J & Sorbie, KS 2012, 'Dual chelant mechanism for the deployment of scale inhibitors in controlled solubility/precipitation treatments' Paper presented at SPE International Conference on Oilfield Scale, Aberdeen, United Kingdom, 30/05/12 - 31/05/12, pp. 1-14. https://doi.org/10.2118/152870-MS

    Dual chelant mechanism for the deployment of scale inhibitors in controlled solubility/precipitation treatments. / Todd, M.J.; Savian, J.; Sorbie, Kenneth Stuart.

    2012. 1-14 Paper presented at SPE International Conference on Oilfield Scale, Aberdeen, United Kingdom.

    Research output: Contribution to conferencePaper

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    Todd MJ, Savian J, Sorbie KS. Dual chelant mechanism for the deployment of scale inhibitors in controlled solubility/precipitation treatments. 2012. Paper presented at SPE International Conference on Oilfield Scale, Aberdeen, United Kingdom. https://doi.org/10.2118/152870-MS