Maximizing polymer performance to unlock field potential

Leena Nurmi is a Senior Research Scientist at Kemira. As one of our experts on chemical enhanced oil recovery (cEOR), her work is focused on the development of polymer chemistry solutions to improve recovery efficiencies of Kemira’s customers’ fields.

One of the things Leena loves about her job is being able to work closely with customers and seeing the positive impact. “Everything we do is based on a customer need. Our sales and research teams are always communicating with customers and proactively bringing new solutions to the table,” she says.

Before joining Kemira in 2015, Leena earned her PhD in polymer chemistry from Aalto University in Finland, then started her career at VTT Technical Institute of Finland. Now, she enjoys applying her knowledge to real-world situations and helping customers improve efficiency and sustainability.

Calculating the advantage of alkali polymer flooding

Leena recently collaborated with OMV to research the performance of alkali polymer (AP) flooding in a mature onshore field and is presenting the findings at SPE ATCE 2022. AP flooding is a promising cEOR method that increases incremental oil recovery by taking advantage of polymer performance in high pH environments, in this case, increasing injectivity and decreasing and costs..

“AP flooding doesn’t come without its challenges,” Leena highlights: “It’s essential to carefully select the alkali and polymer type, as well as the concentration. With this study we were able to take a closer look at how key variables impact polymer performance, and how we can optimize our chemistry for certain conditions.”

Deep in the science

As part of the study, Leena and the team sought to understand changes in polymer rheology in high pH conditions. They conducted phase behavior tests, as well as single/two-phase core floods with aged and non-aged polymer solutions. They also measured adsorption of the aged polymer and the interfacial tension. They performed aging experiments in anaerobic conditions at reservoir temperature and through an accelerated method at elevated temperature. The degree of polymer hydrolysis over time was determined and linked to viscosity performance.

The findings are exciting because it means our customers will be able to use lower polymer concentrations, reducing their overall operating costs.

Promising results for high pH reservoirs

The team observed an increased initial rate of polymer hydrolysis by a factor of 100 compared to hydrolysis at a neutral pH level. As a result, there was a rapid 160% increase in polymer solution viscosity compared to initial conditions thus reducing the water-oil mobility ratio. Efficient oil displacement was observed with aged polymer.

This result, combined with measurements from the other testes, led to the conclusion that it’s possible have increased polymer viscosity at reservoir conditions, and that displacement efficiency between aged and non-aged polymer solutions are similar.

“The findings are exciting because it means our customers will be able to use lower polymer concentrations, reducing their overall operating costs,” explains Leena.

R&D with an impact

“This research is important for operators considering a polymer flood for their field. The more we know about polymer flooding in different reservoirs under different conditions, the better we can predict whether this technology will deliver the efficiencies our customers are looking for,” she explains.

Aside from the cost benefits, some companies see reduced environmental footprint as an attractive reason for implementing this cEOR method. “Polymer flooding can reduce the amount of water being circulated and treated in an oilfield, which means direct savings in energy,” Leena emphasizes.

As more energy companies set ambitious ESG targets, Leena believes that cEOR will be one method that is adopted to achieve these, by improving efficiencies and extending the life of existing fields.

As for the next frontier of cEOR? Leena says digitalization is a trend to watch – perhaps because she has seen Kemira’s predictive analytics platforms transform chemistry selection and chemical dosing in other water-intensive industries like pulp and paper.

Leena Nurmi
Job title
Sr Research Scientist, Oil & Mineral Processing
At Kemira
Since 2015
Topics to watch
Alkali polymer flooding, digital solutions
Words to live by
Stay curious and pay attention
What motivates me
Learning and understanding something that looks unexplainable then gradually becomes explainable