Low-Temperature Composition with Two Gel-Forming Components for Water Shutoff and Enhanced Oil Recovery

To enhance oil recovery and limit water inflow in the fields with a low reservoir temperature (20-23 degrees C), a new low-temperature nanostructured composition with two gel-forming components (polymer and inorganic) with improved rheological characteristics was developed at the Institute of Petroleum Chemistry SB RAS. Laboratory studies of gelation kinetics, rheological and filtration characteristics in the system polyvinyl alcohol (PVA) - boric acid - aluminum salt - carbamide - hexamethylene tetramine (HMTA) - polyol - water are presented. At a temperature of 20-23 degrees C, this system forms coherently dispersed nanoscale structures of gel-ingel type, with viscosity 2.4-6.8 times higher and elasticity 1.4-2.3 times higher than those of the gels with only one gel-forming component. The formation of gel directly in the reservoir leads to a selective water shutoff, a change in the direction of filtration flows, a decrease in water cut, and a limitation of breakthroughs of the injected working agent into production wells. Laboratory studies demonstrated the high efficiency of the composition for flow redistribution and additional displacement of oil from the channels with very high permeability. The composition is applicable to reduce water cut and to limit water inflow in cold wells, which allows us to recommend it for use on cold producing and injection wells with complicated geological structure of the formation, with highly permeable faults, cracks and washed channels, in particular, to limit water inflow and enhance oil recovery in the Permian-Carboniferous deposits of high-viscosity oil of the Usinsk field with the natural operating mode of development. Expected result: enhancement in the oil recovery factor (ORF), a decrease in the water cut of the product, and intensification of oil production.