Barium and Strontium Sulfate Solid-Solution Formation in Relation to North Sea Scaling Problems

Summary This paper presents the results of laboratory experiments carried out to investigate the formation of barium sulfate and strontium sulfate [(Ba, Sr)SO4] solid solution in multi-pressure-tapped cores. Two brines, one barium- and strontium-rich and the other sulfate-rich, were mixed in a core plug. Pressure differentials were measured and the changing permeability distribution along the core length was calculated. The morphology and chemical analysis of scaling crystals as shown by scanning electron microscopy (SEM) are presented. Results show a large extent of permeability damage caused by (Ba, Sr)SO4 solid solution deposits on the rock pore surface. The rock permeability decline and morphology and size of the scaling crystals indicate the influence of the supersaturations of BaSO4 and SrSO4 and the concentration ratio of barium to strontium ions.