Analysis of Sulphonated Polymers in Oilfield Brines

Abstract Residual scale inhibitor analysis in produced waters is recognised as an ongoing challenge for many offshore production environments, particularly for the sulphonated co-polymers. This paper builds on work recently presented in SPE 131100 and describes a number of further developments made to enable rapid, accurate, reliable and robust analysis of sulphonated polymers in oilfield brines. This includes more appropriate solid phase extraction (SPE) techniques which demonstrate near 100% retention of sulphonated polymers from brines of different salinities and therefore negate the requirement for dialysis. Whereas the previous paper focused on bench top SPE (solid phase extraction) techniques which demonstrated very efficient assay in synthetic brines, this work progresses and demonstrates the use of the techniques in real produced waters. This paper then advances further to illustrate the progress made in HPLC based techniques including those using GPC based separation coupled with modern highly-sensitive detectors for more routine / automated assay of sulphonated and other polymeric inhibitors. In summary, the paper will present results and methodologies which enable accurate residual assay of sulphonated co-polymers by both benchtop SPE approaches as well as HPLC approaches in both synthetic and real produced waters. These methodologies therefore remove one of the limitations of sulphonated co-polymers compared with other scale inhibitor species and are expected to form the basis of ongoing residual assay for sulphonated polymers in coming years.