Open Access

ARTICLE

Application of a Waste Cotton–Based Graft-Modified Polymer in Shale Gas Water-Based Drilling Fluids: Rheological Regulation, Filtration Control, and Mechanism

Feng Dai¹, Jiajun Xie¹, Yingmin Liu¹, De Heng¹, Yinfu Han^2,3, Shanshan Hou^2,3,*

1 Sichuan Changning Gas Development Co., Ltd., Changning, China
2 Collaborative Innovation Center for Unconventional Oil and Gas, Yangtze University, Wuhan, China
3 Hubei Engineering Research Centers for Clean Production and Pollution Control of Oil and Gas Fields, Jingzhou, China

* Corresponding Author: Shanshan Hou. Email:

Journal of Polymer Materials 2026, 43(2), 17 https://doi.org/10.32604/jpm.2026.080437

Received 09 February 2026; Accepted 12 May 2026; Issue published 30 June 2026

Abstract

With the increasing emphasis on green, low-carbon, and sustainable development in shale gas drilling fluids, the utilization of waste biomass resources to develop high-performance drilling fluid additives has emerged as an important research direction that balances engineering requirements with environmental responsibility. In this study, waste cotton–derived polyanionic cellulose (bio-PAC) was employed as the base material, and sulfonate and carboxylate functional groups were introduced via free-radical graft copolymerization to synthesize a modified cellulose polymer, PAC-g-(sodium vinyl sulfonate, SVS/sodium methallyl sulfonate, SMAS/methacrylic acid, MAA). Structural characterization confirmed the successful grafting of the target functional groups onto the cellulose backbone. The resulting polymer exhibited high thermal stability, with a decomposition temperature up to 330°C under a nitrogen atmosphere, and demonstrated favorable environmental compatibility (EC₅₀ = 73,000 mg/L). Performance evaluation showed that, in bentonite-based mud systems, the addition of 30 g/L PAC-g-(SVS/SMAS/MAA) followed by aging at 160°C for 16 h resulted in apparent viscosity (AV) retention rates of 81.3%, 73.6%, and 76.4% in freshwater, saturated brine, and mixed-salt based muds, respectively, while the corresponding low-temperature low-pressure (LTLP) filtration volumes were all below 5.0 mL. In shale gas water-based drilling fluid systems, when the dosage was 20 g/L, the drilling fluids maintained stable rheological structures after high-temperature aging at 160°C–180°C, with AV values of 33.5–42.5 mPa·s and yield point (YP) values exceeding 8.5 Pa, significantly outperforming commercial hydroxyethyl cellulose (HEC)– and polyanionic cellulose (PAC)–treated systems. Meanwhile, the high-temperature high-pressure (HTHP) filtration volumes were reduced to 9.8–18.6 mL, corresponding to reduction rates of 82.2%–91.3%. Scanning electron microscopy (SEM) observations of the filter cakes revealed that PAC-g-(SVS/SMAS/MAA) promoted the formation of continuous and compact filtration barrier structures under high-temperature conditions, thereby effectively inhibiting particle migration and pore connectivity. These results demonstrate that the developed polymer can simultaneously achieve significant viscosity enhancement and efficient filtration control in high-temperature shale gas water-based drilling fluids, indicating promising potential for practical engineering applications.

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