PREDICTION OF SCALE PROBLEMS DUE TO INJECTION OF INCOMPATIBLE WATERS.

A newly developed model to predict chemical compatibilities in waterflood operations is described. The model calculates the coprecipitation of BaSO//4, SrSO//4, and CaSO//4 at various locations in field operations as mixtures of injection and reservoir waters flow through injection wells, reservoir, and production wells into surface facilities. As its data base, the model uses comprehensive data of actually measured solubilities in fairly complex oilfield and geothermal brines at various temperatures and at saturation or atmospheric pressure. The solubilities at high pressures are calculated using thermodynamic parameters. The application of the model is illustrated by examples involving two reservoir and two injection waters.