Development of an ASP formulation for a sandstone reservoir with divalent cations

作者：Panthi Krishna; Clemens Torsten; Mohanty Kishore K^*

来源：Journal of Petroleum Science and Engineering, 2016, 145: 382-391.

DOI：10.1016/j.petrol.2016.05.034

• Live oil
• ASP flood
• Sandstone reservoir
• Enhanced oil recovery
• Ultra-low IFT
• Chelating agents

The goal of this work is to develop an ASP formulation for a sandstone reservoir with divalent cations in the injection brine. Development of an ASP formulation for the field condition involves starting with simplified conditions and adding the complexities incrementally. The surfactant system was first identified for the dead oil and softened injection brine. The surfactant system was then modified to work with the simulated live oil and the actual injection brine. The surfactant systems were first tested in outcrop cores. The cumulative oil recovery was not very high (below 90% OOIP) initially. The surfactant system was modified again to achieve a negative slope in the activity diagram; the preflush was modified to not have any alkali. These modifications were tried first in the field core with the simulated live oil and the oil recovery was very high (98% OOIP). The same formulation was then tested in the field core with the live oil and the cumulative oil recovery was 95% OOIP. The pressure gradients were reasonable and adsorption was low. This study showed that sodium carbonate can be used in an ASP formulation in a field brine if enough EDTA can be added to sequester the divalent ions. The ASP formulation should be such that the optimal salinity (and the three-phase salinity range) should increase with water-oil-ratio. The preflush should not include alkali, which could extract soap from the residual oil ahead of the synthetic surfactants. Well-designed ASP formulations can reduce the oil saturations to 1-3% in field cores.

• 出版日期2016-9