Water plugging mechanism of petroleum resin suspension profile modification and its performance

Key words:  high-temperature and high-salinity oil reservoir  profile modification and water shut off  rheological property  petroleum resin  oil-water selectivity

Abstract:

The conventional organic gels present poor stability, low plugging efficiency, and weak oil-water selectivity of the inorganic agents in the high-temperature and high-salinity conditions. In this paper, the petroleum resin suspension with different softening points was prepared. And the plugging efficiency and oil-water selectivity were evaluated with core-flooding experiments. Furthermore, the rheological property and the suspension morphology were conducted to investigate the plugging mechanism at high temperature and pressure. The results show that this petroleum resin system has good oil-water selectivity. When the permeability is over 8 μm², the plugging efficiency is more than 80％ for the water channel, whereas the reservoir formation damage is only 5.29％. For the sand packs with the permeability ratio of 3.0, it is found that the fractional flow ratio of the high permeability layer decreases gradually with injecting the petroleum resin suspension. And the reversal flow is observed after injecting 0.5VP solutions, since the fractional flow ratio between the high and low permeability layers is below than 1. The petroleum resin changes to Newtonian fluid once the temperature is over than its softening point and the viscosity decreases obviously with higher temperature. However, the viscosity is still over 2.2 Pa·s at 150 ℃. When the temperature is over the softening point, the viscous force could account for the firm adsorption at sand surface, which plays the key role in the plugging process.