4.: Scaling

Mineral scale depositional problems are regularly encountered in oilfield systems, and the management of those issues represents a significant operational cost for many fields (Frenier and Ziauddin 2008). Deposition can occur as a result of mixing two incompatible water compositions or because of changes in temperature, pressure, or pH. Consequently, it should come as no surprise that scaling problems are regularly encountered in waterfloods. The location of scaling problems will be influenced by the flood architecture—whether injection is taking place into the water leg (peripheral injection) or into the oil column (pattern injection). Scaling will also be affected by the extent to which the injected water contacts and mixes with the formation water, so it will be influenced by the overall sweep efficiency. If the sweep is good, the majority of the reservoir will be contacted, and mixing will be much better than it would have been if the injection water had short circuited the majority of the reservoir through a high-permeability streak and broken through very rapidly at the producer. It is reasonable to expect that the location of mixing and the amount of injection water in the produced water will change as the flood progresses, so it is therefore also reasonable to expect that the scaling risks will change with time.