51314-4100-Poly-Phosphino Carboxyllic Acid (PPCA) Scale Inhibitor for Application in Precipitation Squeeze Treatments: The Effect of Molecular Weight Distribution

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Product Number: 51314-4100-SG

ISBN: 4100 2014 CP

Author: Nazia Farooqui

Publication Date: 2014

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Poly-Phosphino Carboxyllic Acid (PPCA) polymeric scale inhibitors are widely used for downhole application in oilfield squeeze treatments. These species must perform the dual role of inhibiting scale formation at low concentration levels (~2 to 20ppm) whilst giving acceptably long return curves at the wellbore. Both of these design aspects of polymeric scale inhibitors – inhibition efficiency and retention - are thought to be functions of the polymer molecular weight.The work reported in this paper studies how the Molecular Weight Distribution (MWD) governs the phase behaviour of PPCA as well as other properties such as inhibition efficiency and its detection by ICP and wet chemical assay. Several novel findings are reported including:1. MWD results (Mw Mn and PDI) were determined for different fractions of PPCA including the Stock solution as well as the Precipitate and Supernatant of the PPCA/Ca complex.2. The MWD results obtained for the Precipitated PPCA (Mw = 4900) shows high Inhibition Efficiency since it is rich in higher molecular weight species whereas Supernatant PPCA (Mw = 1300) shows poor Inhibition Efficiency and contains much less high molecular weight material.3. To model the scale inhibitor returns ([PPCA]) from a precipitation squeeze we propose a ‘Stripping Model’ of Precipitated Polymer Complex where dissolution of the original precipitate results in enrichment of the (less soluble) higher molecular weight species.The MWD results for the PPCA polymer have given us some very significant insights into the precipitation/dissolution mechanisms which are occurring in polymer precipitation squeeze processes. We believe that these results are the most detailed to be published in the literature on the PPCA system and that they are of general significance and application for all polymeric scale inhibitor precipitation squeeze treatments.