Synergistic Properties of Phosphonate and Polymeric Scale Inhibitor Blends for Barium Sulphate Scale Inhibition

Abstract

Barium sulphate is one of the most difficult types of scale to inhibit in oil and gas production systems, due to its physical hardness and its chemical and thermal stability. Barium sulphate is most commonly inhibited using either phosphonate or polymeric scale inhibitors (SIs) deployed at sub-stoichiometric concentrations. What is less well known in the oil industry is the effect of using combinations of two (or more) SIs synergistically for enhanced scale inhibition performance. A positive "synergistic" effect would be where, for example, 5ppm of A ϩ 5ppm of B performed better than 10ppm of either A or B. In this paper, a series of static barium sulphate inhibition efficiency (IE) test results are presented, in which a series of pairs of SIs have been tested to determine their synergistic properties at pH 5.5 and 95°C. Polymers can be blended with phosphonates, or alternatively pairs of phosphonates or polymers may be applied. In all cases, the synergistic IE is compared with the IE of each SI tested independently at the mass dosage (i.e. the same concentration in mg/L or ppm). Each separate single SI used in the work has been tested previously for barium sulphate IE at pH 5.5, 95°C in order to determine the minimum inhibitor concentration (MIC) for each species (Shaw et al, 2012a(Shaw et al, , 2012b. Previously, 9 phosphonate and 9 polymeric SIs have been tested individually and, in this work, 34 SI combinations have been tested to examine their synergistic properties. The MICs of the synergistic blends are compared with the normal MICs of the individual SIs. Surprisingly, in most cases, the IE of the blends is usually higher over the range of SI concentrations tested (i.e. the MIC of the blend is lower), compared to that of each SI tested separately. Certain "pairs" of SIs used together yield a significantly beneficial effect, e.g. DETPMP and HMTPMP. Some mechanistic reasons why these synergistic pairs work particularly well are suggested.

Mechanistic Investigation of Adsorption Behavior of Two Scale Inhibitors on Carbonate Formations for Application in Squeeze Treatments

“…Finally, DETPMP has been retained more on carbonates (both calcite and limestone) than PPCA, which can be rationalized in reference to the different functional groups in the SIs. DETPMP has phosphonate functional groups, which are more active than carboxylic acid groups . Thus, the reactivity of DETPMP with Ca 2+ is higher than that of PPCA, resulting in more precipitate being formed and a corresponding increase in the apparent adsorption level for DETPMP.…”

State of the art of synthetic threshold scale inhibitors for mineral scaling in the petroleum industry: a review

“…In some cases two different classes of inhibitors can be blended together usually giving a synergistic effect, better inhibition effect than a single inhibitor, such inhibitors are referred to as blended scale inhibitors. For example, organic polymers and phosphonate inhibitors can be blended together to offer synergistic behavior (Shaw and Sorbie 2014). The reason for the resulted synergistic behavior is predicted to be that different inhibitor classes act via different mechanisms; thus, the combination of these mechanisms results in better inhibition (Kumar et al 2018;Shaw and Sorbie 2014).…”

“…For example, organic polymers and phosphonate inhibitors can be blended together to offer synergistic behavior (Shaw and Sorbie 2014). The reason for the resulted synergistic behavior is predicted to be that different inhibitor classes act via different mechanisms; thus, the combination of these mechanisms results in better inhibition (Kumar et al 2018;Shaw and Sorbie 2014). Shaw and Sorbie (Shaw and Sorbie 2014) researched synergetic properties due to blends of phosphonate and polymeric scale inhibitors.…”

“…The reason for the resulted synergistic behavior is predicted to be that different inhibitor classes act via different mechanisms; thus, the combination of these mechanisms results in better inhibition (Kumar et al 2018;Shaw and Sorbie 2014). Shaw and Sorbie (Shaw and Sorbie 2014) researched synergetic properties due to blends of phosphonate and polymeric scale inhibitors. According to their study, only 5 (out of 34) scale inhibitor blends showed detrimental inhibition properties; most of the blends showed synergistically enhanced inhibition efficiencies.…”

Structure, Stoichiometry, and Modelling of Mixed Calcium Magnesium Phosphonate Scale Inhibitor Complexes for Application in Precipitation Squeeze Processes

“…Both Ca 2ϩ and Mg 2ϩ occur naturally in high concentrations in field formation water and sea water brines in which SIs are deployed. The study of metal binding to SIs is important with regard to both precipitation squeeze processes and also to scale inhibition mechanisms (Boak, 2013;Boak et al, 1999;Cushner et al, 1988;Graham et al, 1997Graham et al, , 2003Shaw, 2012;Shaw et al, 2012aShaw et al, , 2012bShaw et al, , 2012cShaw and Sorbie, 2013a, 2013b, 2013c, 2014a, 2014b, 2014cSorbie et al, 2000;Sorbie and Laing, 2004;Yuan et al, 1997Yuan et al, , 1998Yuan, 2001Yuan, , 2002. For example, during barium sulphate inhibition, Ca 2ϩ plays a crucial positive role in the inhibition mechanism.…”