Preparation and identification of carboxymethyl cellulose-degrading enzyme candidates for oilfield applications

• Published in: Journal of biotechnology 2022-03, Vol.347, p.18-25
• Main Authors: Scheffer, Gabrielle, Rachel, Natalie M., Ng, Kenneth K.S., Sen, Arindom, Gieg, Lisa M.
• Format: Article
• Language: English
• Subjects: Biodegradation; Carboxymethyl cellulose; Carboxymethylcellulose Sodium - metabolism; Cellulase; Cellulase - metabolism; Cellulases - metabolism; Filter cake; Hydraulic fracturing; Oil and Gas Fields; Polymers; Xylanase
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2022.02.001

Carboxymethyl cellulose (CMC) is often used during hydraulic fracturing (fracking) operations as a fluid viscosifier to facilitate proppant delivery. However, the accumulation of residual CMC at fracture faces can result in formation damage, thereby impeding oil and gas recovery. Whereas harsh chemical oxidizers are typically added to disrupt these polymer accumulations, there is now industrial interest in developing clean, biological approaches for the degradation of CMC under fracking conditions. Using a methanogenic culture known to utilize CMC under conditions typically found in oil fields, we developed an efficient method to isolate and purify CMC-degrading enzymes. Initial purification and concentration of cellular components produced an increase in exo-ß-(1,4)-exoglucanase and ß-(1,4)-glucosidase activities by 9-fold and 26-fold, respectively. Partially purified extracts provided substantial degradation of CMC as monitored by viscosity reduction within three hours at 50 °C, an improvement over the untreated cell-free extract which required 48 h to achieve similar viscosity values, outperforming a commercially-available cellulase preparation. Putative cellulases were identified within the isolated enzyme population, with endo-ß-(1,4)-xylanase from Caldicoprobacter faecalis hypothesized to be an important contributor to CMC degradation. This study demonstrates that enzyme technology holds great promise as a viable approach to degrade CMC accumulations under field conditions. •Hydraulic fracturing is a technique to recover oil and gas from unconventional reservoirs.•Viscosifiers facilitate fluid delivery, but can accumulate and prevent effective recovery.•Enzymatic degradation of accumulations is an attractive alternative to oxidizers.•Novel enzymes capable of degrading accumulations have been partially purified and characterized.