Experimental Investigation of the Interaction between a Phosphate Ester Scale Inhibitor and Carbonate Rocks for Application in Squeeze Treatments

Studying the interaction between scale inhibitors (SIs) and chemically-reactive carbonate minerals is crucial for determining SI retention in “squeeze” treatments. This study investigated the retention of the environmentally-friendly SI, polyhydric alcohol phosphate ester (PAPE), on calcite and dolomite substrates. Elemental analysis of the supernatant solution, pH measurement and Environmental Scanning Electron Microscopy (ESEM) with Energy Dispersive X-ray analysis (EDX) were all used to investigate SI retention and to identify the morphology/composition of the resultant SI-Ca precipitates. Results revealed that PAPE was retained by calcite via pure adsorption at an initial test pH (pH0) of 4 and then precipitation at pH0 6. In contrast, the PAPE/dolomite system was found to be effectively pH independent, with precipitation dominating at both pH0 values. Any temperature effect was negligible for dolomite/PAPE retention, while with calcite, retention was smaller at lower temperature, attributed to the te...