Investigation into emulsion blockage removal using thermochemical fluid

A novel approach to exploit thermal energy released from the exothermic reactions of aqueous solution of thermochemical reactants (ammonium chloride and sodium nitrite), in controlling formation damage induced by water-in-oil emulsion have been investigated. Essentially, the technology concerns raising the temperature and pressure of the formation above the kinetic stability of emulsion through the heat and pressure generated insitu from the reaction. From the batch experiments to assess the energetic of the thermochemical reaction, it was observed that the temperature of the system could be raised to ≈170 °C (from 100 °C initial temperature) and pressure of 1600 psia, under controlled conditions. A stable water-in-oil (W/O) emulsion was prepared and used as a damaging fluid. Ultimately, about 72% of the W/O emulsion was removed from the core sample by injecting 1 PV of thermochemical fluids. In addition, the pressure profile, observed during the flooding experiment, shows that no precipitation or damage was induced during the thermochemical flooding. Therefore, it is envisaged that the insitu heat generation can mitigate emulsion blockage problem, and offers advantages over the existing methods considering environmental friendliness and damage removal efficiency.