{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T15:09:04Z","timestamp":1788793744307,"version":"build-2803163510"},"reference-count":31,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,6]],"date-time":"2026-09-06T00:00:00Z","timestamp":1788652800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Gels"],"abstract":"<jats:p>To address the susceptibility of polymer gels to syneresis and failure under high-temperature, high-salinity (HTHS) reservoir conditions, a zwitterionic terpolymer was synthesized from acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and dimethyldiallylammonium chloride (DMDAAC), and subsequently crosslinked with a phenolic system to produce an intramolecular salt-structured polymer gel with exceptional thermal and saline tolerance. Through systematic formulation optimization, the optimal composition was established as 0.3 wt% zwitterionic polymer, 0.03 wt% resorcinol, 0.3 wt% hexamethylenetetramine, and 0.1 wt% thiourea. X-ray photoelectron spectroscopy and zeta potential measurements confirmed that quaternary ammonium cations and sulfonate anions on the polymer chains associate via electrostatic attraction to form intramolecular salt bridges, which induce an anti-polyelectrolyte effect and thereby confer superior salt tolerance and thermal stability. Following aging for 140 days at 115 \u00b0C in formation water, the gel exhibited a syneresis rate below 30%, demonstrating favorable long-term stability under the tested high-temperature and high-salinity conditions. Thermogravimetric analysis and differential scanning calorimetry further characterized the thermal-transition behavior of the gel under programmed heating conditions. Scanning electron microscopy revealed a homogeneous honeycomb-like porous crosslinked network. Rheological testing demonstrated a storage modulus (G\u2032) of 1.115 Pa and a loss modulus (G\u2033) of 0.205 Pa, indicating an elasticity-dominated viscoelastic response and strong resistance to shear deformation. Single-core plugging experiments showed that at an injection volume of 0.2 PV, the gel achieved a plugging efficiency of 85.15% and a breakthrough pressure gradient of 18.6 MPa\/m, with significant secondary plugging capability. In a heterogeneous dual-core model with a permeability contrast of approximately 10, the diversion rate into the low-permeability layer increased to 73.6%, effectively improving the water injection profile. This intramolecular salt-structured molecular design demonstrates potential for deep-profile control under high-temperature and high-salinity reservoir conditions.<\/jats:p>","DOI":"10.3390\/gels12090819","type":"journal-article","created":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T13:53:28Z","timestamp":1788789208000},"page":"819","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Preparation and Performance Evaluation of Temperature-Resistant and Salt-Resistant Zwitterionic Polymer Gel"],"prefix":"10.3390","volume":"12","author":[{"given":"Meilong","family":"Fu","sequence":"first","affiliation":[{"name":"College of Petroleum Engineering, Yangtze University, Wuhan 430100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shoufei","family":"Lu","sequence":"additional","affiliation":[{"name":"College of Petroleum Engineering, Yangtze University, Wuhan 430100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yangjie","family":"Fan","sequence":"additional","affiliation":[{"name":"College of Petroleum Engineering, Yangtze University, Wuhan 430100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuxin","family":"Bai","sequence":"additional","affiliation":[{"name":"College of Petroleum Engineering, Yangtze University, Wuhan 430100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1016\/j.petrol.2016.04.017","article-title":"Experimental study on a new plugging agent during CO2 flooding for hetero-geneous oil reservoirs: A case study of Block G89-1 of Shengli oilfield","volume":"146","author":"Li","year":"2016","journal-title":"J. Pet. Sci. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Mi, L., Jiang, H., Pei, Y., Li, J., Tian, J., Xin, Y., Yan, B., and Killough, J.E. (2016). Microscopic oil and water percolation characteristic inves-tigation of water flood reservoir in ultrahigh water cut period. SPE Trinidad and Tobago Section Energy Resources Conference, SPE.","DOI":"10.2118\/180864-MS"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Wang, D., and Tand, J. (1986). Production Technology of Daqing Oil-Field During its High Water-Cut Stage. SPE International Oil and Gas Conference and Exhibition in China, SPE.","DOI":"10.2118\/14847-MS"},{"key":"ref_4","unstructured":"Zou, X., Yu, G., Huang, Y., Thanh, T., Francisco, C., Li, Y., Tian, X., Tong, J., Ge, L., and Halomoan, P.M. (2013). Best Practices and Application of Integrated Fit for Purpose Technologies to Revitalise High Water Cut Mature Fields\u2014A Case History from Offshore South China. IPTC 2013: International Petroleum Technology Conference, European Association of Geoscientists & Engineers."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Zhao, Y., Jiang, H., Li, J., Wang, C., Gao, Y., Yu, F., and Su, H. (2017). Study on the classification and formation mechanism of microscopic remaining oil in high water cut stage based on machine learning. Abu Dhabi International Petroleum Exhibition and Conference, SPE.","DOI":"10.2118\/188228-MS"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"706","DOI":"10.5614\/j.eng.technol.sci.2015.47.6.9","article-title":"Surfactant-Polymer Coreflood Simulation and Uncertainty Analysis Derived from Laboratory Study","volume":"47","author":"Hakiki","year":"2015","journal-title":"J. Eng. Technol. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4701","DOI":"10.1021\/acs.energyfuels.5b00149","article-title":"Mechanism study of the cross-linking reaction of hydrolyzed polyacrylamide\/Ac3Cr in formation water","volume":"29","author":"Zhang","year":"2015","journal-title":"Energy Fuels"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"9351","DOI":"10.1021\/acs.energyfuels.6b02230","article-title":"Influence of Hydrolyzed Polyacrylamide (HPAM) Molecular Weight on the Cross-Linking Reaction of the HPAM\/Cr3+ System and Transportation of the HPAM\/Cr3+ System in Microfractures","volume":"30","author":"Zhang","year":"2016","journal-title":"Energy Fuels"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/j.jiec.2017.05.023","article-title":"An experimental study on positioning conformance control of starch gelant in the heterogeneous porous media by using CT technology","volume":"54","author":"Zhang","year":"2017","journal-title":"J. Ind. Eng. Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"012907","DOI":"10.1115\/1.4035146","article-title":"Experimental Study on a New Type of Water Shutoff Agent Used in Fractured Low Permeability Reservoir","volume":"139","author":"Zhang","year":"2017","journal-title":"J. Energy Resour. Technol.-Trans. ASME"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"13063","DOI":"10.1021\/acs.energyfuels.7b02897","article-title":"Polymer Gel Systems for Water Management in High-Temperature Petroleum Reservoirs: A Chemi-cal Review","volume":"31","author":"Zhu","year":"2017","journal-title":"Energy Fuels"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1103","DOI":"10.1016\/j.matpr.2021.07.506","article-title":"Study on the effect of cross-linked gel polymer on water shutoff in oil wellbores","volume":"48","author":"Sharma","year":"2022","journal-title":"Mater. Today Proc."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"109051","DOI":"10.1016\/j.petrol.2021.109051","article-title":"Review of transport mechanisms and numerical simulation studies of preformed particle gel for con-formance control","volume":"206","author":"Leng","year":"2021","journal-title":"J. Pet. Sci. Eng."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3367","DOI":"10.1007\/s11430-023-1417-8","article-title":"Development and preservation mechanism of deep and ultra-deep car-bonate reservoirs","volume":"67","author":"Shen","year":"2024","journal-title":"Sci. China-Earth Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"384","DOI":"10.1016\/j.petsci.2023.11.017","article-title":"A review of reservoir damage during hydraulic fracturing of deep and ultra-deep reservoirs","volume":"21","author":"Zhang","year":"2024","journal-title":"Pet. Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1021\/ef502505k","article-title":"Gelation Study on a Hydrophobically Associating Polymer\/Polyethylenimine Gel System for Water Shut-off Treatment","volume":"29","author":"Bai","year":"2015","journal-title":"Energy Fuels"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1080\/10916460701204594","article-title":"A review of the partly hydrolyzed polyacrylamide Cr(III) acetate polymer gels","volume":"26","year":"2008","journal-title":"Pet. Sci. Technol."},{"key":"ref_18","unstructured":"Song, H., Pope, G.A., and Mohanty, K.K. (October, January 28). Thermal Stability of Acrylamide-Based Polymers at High Temperature and High Salinity. Proceedings of the SPE Canada Heavy Oil Conference, Virtual."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Wang, J., AlSofi, A.M., and AlBoqmi, A.M. (2016). Development and evaluation of gel-based conformance control for a high salinity and high temperature carbonate. SPE EOR Conference at Oil and Gas West Asia, SPE.","DOI":"10.2118\/179796-MS"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"108416","DOI":"10.1016\/j.petrol.2021.108416","article-title":"Investigation of a high temperature gel system for application in saline oil and gas reservoirs for profile modification","volume":"202","author":"Liu","year":"2021","journal-title":"J. Pet. Sci. Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1038\/pj.2013.99","article-title":"Development of enhanced nanocomposite preformed particle gels for conformance control in high-temperature and high-salinity oil reservoirs","volume":"46","author":"Bai","year":"2014","journal-title":"Polym. J."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1002\/pat.4455","article-title":"In situ organically cross-linked polymer gel for high-temperature reservoir conformance control: A review","volume":"30","author":"Amir","year":"2019","journal-title":"Polym. Adv. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"20467","DOI":"10.1007\/s13369-025-10595-y","article-title":"Smart Crosslinked Polymer Gels for Water Shutoff in Oil Reservoir: A Comprehensive Review on Materials, Mechanisms, and Field Applications","volume":"50","author":"Parmar","year":"2025","journal-title":"Arab J. Sci. Eng."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3956","DOI":"10.1021\/acsapm.3c03140","article-title":"Synthesis and Properties of Temperature- and Salt-Resistant CP(AM-AMPS-DMDAAC) Nano-spheres for Oil Displacement","volume":"6","author":"Li","year":"2024","journal-title":"ACS Appl. Polym. Mater."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"161087","DOI":"10.1016\/j.cej.2025.161087","article-title":"A zwitterionic polymer filtrate reducer with enhanced anti-polyelectrolyte effect for high-temperature and high-salinity conditions","volume":"508","author":"Gao","year":"2025","journal-title":"Chem. Eng. J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"49080","DOI":"10.1021\/acsomega.3c06989","article-title":"Synthesis and Characterization of a Res-in\/Acrylamide-2-acrylamide-2-methylpropane Sulfonate-Diallyl Dimethyl Ammonium Chloride N vinyl-2-pyrrolidinone Polymer Microcapsule Gelling Agent for Oil and Gas Field Transformation","volume":"8","author":"Liu","year":"2023","journal-title":"ACS Omega"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Li, X., Fu, M., and Hu, J. (2024). Preparation and Performance Evaluation of Temperature-Resistant and Salt-Resistant Gels. Gels, 10.","DOI":"10.3390\/gels10050337"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Li, X., Liu, S., Zhang, J., Han, S., Zhao, L., Xu, A., Wang, J., Zhou, F., and Li, M. (2024). High-Temperature-Resistant Profile Control Sys-tem Formed by Hydrolyzed Polyacrylamide and Water-Soluble Phenol-Formaldehyde Resin. Gels, 10.","DOI":"10.3390\/gels10060413"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3630","DOI":"10.2118\/210593-PA","article-title":"Performance Evaluation of High-Strength Polyethyleneimine Gels and Syn-eresis Mechanism under High-Temperature and High-Salinity Conditions","volume":"27","author":"Guo","year":"2022","journal-title":"SPE J."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"13568","DOI":"10.1021\/acsami.0c02247","article-title":"Brine-Soluble Zwitterionic Copolymers with Tunable Adsorption on Rocks","volume":"12","author":"He","year":"2020","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"17280","DOI":"10.1021\/acs.energyfuels.5c02907","article-title":"Electrostatically Enhanced Swelling Stabil-ity and Mechanics of Polyzwitterionic P(AM\/AMPS\/DMC) Hydrogels for High-Temperature and High-Salinity Reservoir En-vironment","volume":"39","author":"Su","year":"2025","journal-title":"Energy Fuels"}],"container-title":["Gels"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2310-2861\/12\/9\/819\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T14:21:41Z","timestamp":1788790901000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2310-2861\/12\/9\/819"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,6]]},"references-count":31,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["gels12090819"],"URL":"https:\/\/doi.org\/10.3390\/gels12090819","relation":{},"ISSN":["2310-2861"],"issn-type":[{"value":"2310-2861","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,6]]}}}