Salt-Tolerant Non-Crosslinked Polymer Networks for High-Temperature Weighted Fracturing Fluids in Deep Hydrocarbon Reservoirs.
5 affiliations
- 1CNPC Tarim Oilfield Company, Korla 841000, China.
- 2R&D Center for Ultra Deep Complex Reservoir Exploration and Development, CNPC, Korla 841000, China.
- 3Engineering Research Center for Ultra-Deep Complex Reservoir Exploration and Development, Xinjiang Uygur Autonomous Region, Korla 841000, China.
- 4Xinjiang Key Laboratory of Ultra-Deep Oil and Gas, Korla 841000, China.
- 5School of Oil & Natural Gas Engineering, Southwest Petroleum University, Chengdu 610500, China.
Abstract
High-density potassium formate fracturing fluids require polymers that hydrate in concentrated brine while providing low friction and proppant suspension at high temperature. We hypothesized that the 2-acrylamido-2-methylpropanesulfonic acid (AMPS) content balances salt-tolerant hydration against molar-mass-dependent chain entanglement, enabling a reversible non-crosslinked network. Five hydrophobically associating copolymers based on acrylamide (AM) and AMPS, with AMPS feed contents of 5.5-23.8 wt%, were synthesized by low-temperature micellar copolymerization followed by post-hydrolysis. Polymer structure, molar mass, and solution conformation were determined by proton nuclear magnetic resonance spectroscopy and size-exclusion chromatography coupled with multi-angle light scattering. Hydration and thickening were evaluated in 1.40 g/cm³ potassium formate brine, followed by rheological testing at 160 °C, pipe-flow drag-reduction testing, and static proppant-suspension testing. Increasing the AMPS feed content decreased the weight-average molar mass from 25.83 × 10⁶ to 9.26 × 10⁶ g/mol, increased the chain-conformation exponent from 0.570 to 0.610, and shortened the time required to reach 90% hydration (t₉₀) from approximately 118 to 48 min. SN-4, containing 17.9 wt% AMPS, provided the best overall balance. A 0.60 wt% SN-4 fluid retained approximately 63 mPa·s after shearing at 160 °C and 170 s⁻¹ and recovered 92.1% of its viscosity after 300 s. Fresh and thermally sheared-recovered fluids maintained drag-reduction rates above 60%, and the recovered fluid reduced proppant settling velocity by 97.4%. These results support the proposed balance and demonstrate the potential of this reversible network for high-temperature weighted fracturing fluids in deep hydrocarbon reservoirs.
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BibTeX
@article{liu2026salttolerant,
title = {{Salt-Tolerant Non-Crosslinked Polymer Networks for High-Temperature Weighted Fracturing Fluids in Deep Hydrocarbon Reservoirs.}},
author = {Jv Liu and Xin Qiao and Jianxin Peng and Lili Yan and Qingsong Cheng and Fei Peng and Bowen Zhong and Shulong Chen and Lingfeng Wu and Yang Bai},
journal = {Gels (Basel, Switzerland)},
year = {2026},
month = oct,
doi = {10.3390/gels12100905},
url = {https://europepmc.org/article/MED/42929939},
note = {CC BY},
}
RIS
TY - JOUR
TI - Salt-Tolerant Non-Crosslinked Polymer Networks for High-Temperature Weighted Fracturing Fluids in Deep Hydrocarbon Reservoirs.
AU - Jv Liu
AU - Xin Qiao
AU - Jianxin Peng
AU - Lili Yan
AU - Qingsong Cheng
AU - Fei Peng
AU - Bowen Zhong
AU - Shulong Chen
AU - Lingfeng Wu
AU - Yang Bai
PY - 2026
DA - 2026/10/08
JO - Gels (Basel, Switzerland)
DO - 10.3390/gels12100905
UR - https://europepmc.org/article/MED/42929939
AB - High-density potassium formate fracturing fluids require polymers that hydrate in concentrated brine while providing low friction and proppant suspension at high temperature. We hypothesized that the 2-acrylamido-2-methylpropanesulfonic acid (AMPS) content balances salt-tolerant hydration against molar-mass-dependent chain entanglement, enabling a reversible non-crosslinked network. Five hydrophobically associating copolymers based on acrylamide (AM) and AMPS, with AMPS feed contents of 5.5-23.8 wt%, were synthesized by low-temperature micellar copolymerization followed by post-hydrolysis. Polymer structure, molar mass, and solution conformation were determined by proton nuclear magnetic resonance spectroscopy and size-exclusion chromatography coupled with multi-angle light scattering. Hydration and thickening were evaluated in 1.40 g/cm³ potassium formate brine, followed by rheological testing at 160 °C, pipe-flow drag-reduction testing, and static proppant-suspension testing. Increasing the AMPS feed content decreased the weight-average molar mass from 25.83 × 10⁶ to 9.26 × 10⁶ g/mol, increased the chain-conformation exponent from 0.570 to 0.610, and shortened the time required to reach 90% hydration (t₉₀) from approximately 118 to 48 min. SN-4, containing 17.9 wt% AMPS, provided the best overall balance. A 0.60 wt% SN-4 fluid retained approximately 63 mPa·s after shearing at 160 °C and 170 s⁻¹ and recovered 92.1% of its viscosity after 300 s. Fresh and thermally sheared-recovered fluids maintained drag-reduction rates above 60%, and the recovered fluid reduced proppant settling velocity by 97.4%. These results support the proposed balance and demonstrate the potential of this reversible network for high-temperature weighted fracturing fluids in deep hydrocarbon reservoirs.
SN - 2310-2861
ER -