Modelling the impacts of Polymer flooding and injection brine composition on barium sulphate scale precipitation and its inhibition

Polymer flooding is a mature Enhanced Oil Recovery (EOR) topic that has been studied and successfully applied in a number of hydrocarbon reservoirs. Barium Sulphate (BaSO4) is a serious scale risk that has been encountered in various oil fields. The study illustrates the BaSO4 scale behavior in the polymer flooding process. The behavior of brines mixing and the formation of BaSO4 is different in the polymer flooding compared to the normal water flooding in terms of the timing and amount of scale. This difference depends on the system properties such as polymer viscosity, adsorption and injection brine salinity. Sulphate scale deposition presents a risk in the near wellbore region of production wells that cannot be controlled by continual injection, so a batch treatment called a scale squeeze is required to be applied to the near wellbore region. Different EOR methods impact the scale risk and so have the potential to impact squeeze treatment frequency, chemical cost and differed oil associated with such treatments. The use of low salinity, low sulphate brine combined with polymer not only improves oil recovery, but it also reduces the scale risk in the reservoir and the wellbore.