Scale formation during waterfloods can damage reservoirs far beyond the wellbore region. A comprehensive analysis with geochemical modeling can improve waterflood design in the selection and/ or mixing of source waters and thus, mitigate formation damage arising from injecting incompatible fluids. This method can also predict the types of scales and their severity at various production stages. This will help optimize treatment schedules and thus reduce operation costs.
In the case study of Zone 4, Prudhoe Bay Unit (North Slope, Alaska), the geochemical model was validated with the laboratory analyses of Zone 4 produced water samples. Then it was used to evaluate the impact of mixing formation brine and seawater on rock-fluid interactions and scale formation. The prediction is consistent with the observation of calcite formation in early production at Prudhoe Bay. The model also indicates the precipitation of iron carbonate and iron sulfide scales as the waterflood matures.