Over recent years, there has been an increasing requirement in oilfield scale prevention to replace conventional mineral scale inhibitors (SI) with more environmentally friendly "green" species (GSI). This paper presents the experimental results from static barium sulfate inhibition efficiency tests for three conventional SIs and 11 GSIs. The conventional SIs are DETPMP, PPCA and PVS; and the GSIs are two PPCA-type inhibitors, four polymeric species, three maleic acid inhibitors, a polyaspartate inhibitor and a carboxymethyl inulin. These polymeric GSIs have a range of molecular weights. The objective of this study is to perform a range of inhibition efficiency tests (a) to establish which of the various GSIs tested actually work under which test conditions, and (b) to determine the mechanisms through which they operate, by comparison with the performance of conventional SIs. A wide range of conditions has been used for both "severe" and "moderate" barium sulfate scaling brine mixtures and temperatures of 5°C and 95°C. This study shows that: i. currently available GSIs do work under certain test conditions and would be suitable in terms of inhibition efficiency to tackle specific milder barium sulfate scaling problems; ii. no "ranking" of the green inhibitor species is possible since it varies greatly depending on test conditions (which should be clearly defined for any specific oilfield application); iii. the green scale inhibitors tested do appear to fit into the mechanistic schemes proposed for conventional scale inhibitors. As expected, they generally lie in the polymer region, and operate principally as nucleation inhibition species like PVS and PPCA. © 2006 by NACE International.
- Barium sulfate, mechanisms
- Green scale inhibitors
- Scale inhibitors
- Static barium sulfate inhibition efficiency tests