The Compatibility Experiment Research on Chang 8 Reservoir of Liuluoyu Area in Xiasiwan Oilfield

The Chang 8 formation water in the area of Liuluoyu is of CaCl₂ water type, and the scaling damage is mainly caused by BaSO₄. The injection water was Chang 2 formation water, whose water types and constitutions were similar to Chang 8. Compatibility experiment results showed that with the increasing of temperature and pressure, the tendency of CaCO₃ scaling in single water sample was rising while the tendency of BaSO₄ scaling was decreasing. After the combination of injection water and grinded core, the white precipitate composed of BaSO₄ and CaCO₃ was generated. Test results with water sample of different mix ratio suggested that improving the ratio of injection water could effectively reduce the quantities of precipitates generated from mixed liquids. In addition, with the continuous injection of water, the core's permeability varied slightly, which indicated that mixed water could hardly cause damage to reservoirs.