EOR biopolymers – performance and biodegradability

Polymer flooding methods for IOR purposes rely mostly on synthetic water-soluble polymers, mainly polyacrylamides (HPAM). The use of synthetic polymers has caused environmental concerns and alternatives are therefore sought. A biotechnological solution could involve biopolymers combining polymer properties with an acceptable biodegradability profile. Biopolymers such as xanthan and schizophyllan have long been recognized as the most viable IOR biopolymers due to their favourable properties associated with multi-stranded structures (Fig 1A). A major challenge has been that biopolymers may in fact be too biodegradable, allowing opportunistic microorganisms to degrade the polymers before or during field operation unless large quantities of biocides are used. Xanthan may be chemically modified to improve its rheological properties¹. It is well known that such modifications also tend to reduce access of polymer-degrading enzymes², which are key factors controlling biodegradation. This opens up, for the first time, the possibility of effectively tuning the biodegradability of biopolymers in a controlled way, without rendering them too resistant to biodegradation and without relying on biocides. It is particularly compelling that this may be combined with enhanced rheological properties (Fig. 1B).

This project aims to systematically study the relationship between biodegradability and structural modification of single- and double-stranded xanthan. The study will include screening for xanthan-degrading microorganisms in relevant environments to assess risks associated with uses in IOR.

Figure 1: Structure of xanthan (A) and main hypothesis (B): modification of xanthan adjusts biodegradability to comply with functional and regulatory requirements while retaining or enhancing viscosifying properties. DS = Degree of Substitution

Publications:

Dalheim, M.Ø., Vanacker, J., Najmi, M.A., Aachmann, F.L., Strand, B.L., Christensen, B.E., Efficient functionalization of alginate biomaterials, Biomaterials 80 (2016) 146-156

References:

1.     Roy, A., Comesse, S., Grisel, M., Hucher, N., Souguir, Z., Renou, F. (2014) Biomacromolecules 15(4) 1160

2.     Christensen, B.E., Smidsrød, O. (1996) International journal of biological macromolecules 18(1-2) 93.