Where Does Oilfield Scale Form?
The scaling reaction depends on there being sufficient concentrations of sulfate ions in the injected seawater, and barium, strontium and/or calcium-divalent cations in the formation brine to generate sulfate scale; or on sufficient bicarbonate and calcium ions to allow the formation of carbonate should the physical conditions result in a change in equilibrium. Thus, scale precipitation may occur wherever there is mixing of incompatible brines, or there are changes in the physical condition (such as pressure decline). An overview of all the possible scale formation environments for seawater, aquifer, natural depletion, and produced water reinjection is presented in Fig. 1. • For example, before injection, if seawater injection is supplemented by produced water reinjection (PWRI) • Around the injection well, as injected brine enters the reservoir contacting formation brine • Deep in the formation, owing to displacement of formation brine by injected brine, or owing to converging flow pa
