Synthesis and Application of Hydrophilic Polymer Nanoparticles for Water Shut-Off

Over the last few years, oil companies have devoted much effort to decrease the amount of water that is pumped up with oil, especially from mature reservoirs, where the water production is huge. In addition to reducing the profit margin, the water extracted from an oil field is polluted by different organic and inorganic compounds and must be properly treated before being discharged or reinjected. Alternatively, it must be disposed of with high treatment and/or disposal costs. To overcome costs associated with water treatment/disposal, mechanical and chemical strategies aimed at reducing the amount of extracted water (i.e., water shut-off) are applied. Among them, hydrophilic polymeric micro- and nanogels are promising materials that are gaining increasing interest. They are three-dimensional networks able to retain water by increasing in size and thus creating a physical barrier to the water flowing. In this work, nano- and microabsorbent particles made up of crosslinked poly(methacrylic acid-co-oligo(ethylene glycol) methyl ether methacrylate) p(MAA-co-OEGMA) were synthesized via inverse suspension polymerization in Lamix, an aromatic-free hydrocarbon blend. The formulation was optimized in terms of OEGMA mole fraction to achieve a high swelling in seawater and hence high efficacy in the water shut-off. Finally, the suspension was modified to be produced on a ton scale and injected into an open-hole, partially depleted oil reservoir for a first pilot field test. One-year monitoring was conducted by evaluating the oil productivity as well as the water fraction (i.e., water cut) under conventional extraction procedures. This trial assessed a 30% decrease in the water cut, as well as an increase in the oil production from 5 to 30 m3/day. This confirmed the developed microgels as a promising tool for water shut-off.