Initial stages of barium sulfate formation at surfaces in the presence of inhibitors

The formation of barium sulfate (BaSO4) in the oilfield is known to occur as a precipitation process from the aqueous phase within oil production facilities. This barite deposition causes many problems related to flow assurance. In this paper, the initial stages of barium sulfate deposition on a metallic surface are investigated. The mass rate of deposition of barite on the surface was measured using a quartz crystal microbalance (QCM). The morphology of the deposited BaSO4 was then observed directly with an atomic force microscope (AFM) and the main crystal faces of barite were identified. Both the formation kinetics and the crystallography of the deposited barium sulfate were studied at three supersaturation ratios and in the presence and absence of 2 chemical scale inhibitors, namely, polyphosphino carboxylic acid (PPCA) and diethylene triamine penta acetic acid (DETPMP). In addition, the precipitation of the barite in the bulk phase was also monitored (by turbidity measurements) thus giving a more com...