Can we generate stable pickering emulsions activating naturally occurring nanoparticles in the reservoir for cost effective heavy-oil recovery?

Activating naturally occurring nanoparticles in the reservoir (clays) to generate Pickering emulsions results in low-cost heavy oil recovery. In this study, we tested the stability of emulsions generated using different types of clays and performed a parametric analysis on salinity, pH, water to oil ratio (WOR), and particle concentration; additionally, we report on a formulation of injected water used to activate the clays found in sandstones to improve oil recovery. First, oil-in-water (O/W) emulsions generated by bentonite and kaolinite clays were prepared for bottle tests and zeta potentials of clay suspensions were measured, then the stability of dispersion was measured under various conditions (pH, salinity and WOR). Heavy crude oils (15,640 cP) were used for all experiments. Second, sandpacks with different clay compositions were saturated with heavy-oil samples. Aqueous solutions with various salinity and pH were injected into the oil-saturated sandpacks with a pump. The recoveries were monitored while analyzing the produced samples. Third, glass bead micromodels with known amounts of clays were also prepared to visualize the in-situ behavior of clay particles under various salinity conditions. The transparent mineral oil instead of opaque heavy oil was used in these micromodel tests for better visualization results. The bottle tests showed that 3% bentonite stabilized O/W emulsions under a high WOR (9:1) condition. The addition of 0.04% of NaOH further improved the emulsion stability which was attributed to the reduction of interfacial tension (0.17 mN/M) between the oil and alkali solution. The sandpack flood experiments showed an improved sweep efficiency caused by the swelling of bentonite when injecting low salinity fluid (e.g., DIW). The micromodel tests indicated a wettability change to be more oil-wet under high salinity conditions, and the swelling of bentonite would divert incoming water flow to other unswept areas thus improving sweep efficiency. This paper presents new ideas and recommendations for further research as well as practical applications to generate stable emulsions for improved waterflooding as a cost-effective approach.

Automated summary

This study investigates the use of naturally occurring nanoparticles in reservoirs (clays) to generate Pickering emulsions for low-cost heavy oil recovery. It found that emulsions generated using different types of clays exhibit varying stability under different conditions, and injecting low salinity fluids (such as DIW) can improve sweep efficiency for oil recovery.