THE EFFECT ON SCALE INHIBITOR PERFORMANCE AGAINST BULK (HOMOGENEOUS) AND SURFACE (HETEROGENEOUS) SCALE NUCLEATION AND GROWTH BY THE ADDITION OF FILM FORMING CORROSION INHIBITORS

摘要

It is recognised that chemical interactions between scale inhibitor (SI) and corrosion inhibitor (CI) result in a reduction in the performance efficiency of both chemicals. As reservoir production systems become ever more complex, the requirements for chemical compatibility become greater. This is a particular concern for satellite and deepwater fields in which several wells may be co-produced through very long subsea tie backs. In such systems, chemical / chemical performance compatibilities are essential. Previous work on the issue has mainly been limited to field specific studies with a view to product selection or physical compatibility studies. Examples are drawn in this paper from field cases which demonstrate that interferences between the pre-selected candidate scale inhibitors and corrosion inhibitors can be a major concern. Indeed, final product selection is often based upon the combination of inhibitors that would not interfere with one another, rather than on the absolute performance of the individual products. This paper then attempts to define and rationalise the chemical interactions from a scale prevention perspective. The performance of generic scale inhibitors including phosphonates (DETPMP), phosphino-polycarboxylates (PPCA), polyvinyl sulphonates (PVS) and sulphonate polyacrylate copolymers (VS-Co) have been examined in the presence and absence of four different corrosion inhibitors including two commercial products and two genetic species (including an imidazoline and a quaternary ammonium salt). Furthermore, the impact of CIs on the adhesion of BaSO_4 on metallic surfaces was also assessed both in the presence of SI and in the absence of SI as a means to define the interactions occurring.