Tatneft' PAO : Scientists of TATNEFT Have Developed a New Technology to Enhance Oil Recovery

TatNIPIneft professionals of PJSC TATNEFT have developed and are successfully implementing a new technology for increasing crude oil recovery through using polymer/clay compositions and surfactants (PGK-M technology).

PGK-M technology allows increasing the ongoing crude oil production and the oil recovery factor through increasing the sweep efficiency of the non-homogeneous formation.

The reservoir sweep coverage is improved through locking the formation's watered intervals. In this case the displacement front is redirected to the less permeable interlayers.

The process for increasing the sweep involves injection of an aqueous dispersion of clay powder and polymer: a polymer/clay composition (PGK).

The presence of the polymer macromolecules in the clay powder dispersion leads to the flocculation process, whereby the polymer/clay structures (particles) are formed, which amount and size can be adjusted by varying the concentration of the key components.

The structure of the particles contributes to their merging with each other and formation of macroparticles in the pore space in the washed-out intervals preventing the flow of water. Therefore, the injection of the polymer/clay composition results in the partial or complete blocking of the reservoir's most water-bearing intervals and involvement of the previously non-stimulated oil-saturated zones into the development.

The Increased oil recovery rate is achieved through injection of surface-active agents (surfactants). In the formation the surfactants mainly go to less washed out areas and increase the oil displacement coefficient. The surfactant injection brings down the interfacial tension between 'water-oil-rock' interface, increases the reservoir rock wettability and improves the mobility of oil.

The PGK-M technology has been commercially implemented in the fields of PJSC TATNEFT since 2014. As of January 2016 there were 95 injection wells treatments carried out. The average current specific technological efficiency per well treatment amounted to more than 1,300 tonnes of the incrementally produced oil with the ongoing technological effect.

The guidance document RD 153-39.0-835-13 'Instruction for application of the enhanced oil recovery technology using polymer/clay and surfactant compositions' has been worked out to support the technology.

This engineering development was awarded the IIIrd degree diploma of the contest 'Energy efficient equipment and technologies' held within the framework of the XVIIth International specialized exhibition 'Energy. Resource Saving'.