Microgel polymer flooding is one of enhanced oil recovery (EOR) methods. Polymer systems are injected through injection wells. Main active agents in the polymer systems are microgel particles resulting from the reaction of gelling agents (aluminates) with polyacrylamide solution. These microgel particles are crossed-linked polymer globules from 0.4 to 5 μm in diameter. Microgel systems have better shear degradation resistance than conventional polymer solutions. Enhanced oil recovery is achieved through plugging of high-permeability formation zones and improvement of reservoir sweep.
The advantages of microgel-based EOR techniques are the following: high efficiency even with low concentrations of polyacrylamide and cross-linker, lower cost because domestic environmentally-friendly cross-linkers are used; besides, water mineralization does not matter, neither does weather environment or season.
The primary targets of microgel polymer flooding are sandstone reservoirs with permeability more than 0.1 μm2 developed by contour water flooding.
The paper presents Tatneft PJSC experience of application of microgel polymer systems in the Company’s fields. Well logging confirmed that microgel systems can effectively be used to control conformance and to improve displacement efficiency.
Microgel polymer systems are effective in water-producing and non-uniform permeable multi-zone reservoirs. This technology proved to be particularly effective in the commingled production zones of the Kynovian and the Pashian horizons, as well as in the Bobrikovskian and the Kynovian development targets. It should be noted that the amount of displaced oil differs significantly from one producing well to another, and this is the subject of further study.
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