Pub Date : 2025-12-01DOI: 10.1016/j.petsci.2025.12.011
Yu Wu, Yan-Cheng Zheng, Jian Mu, Fu-Chang You, Zheng-Yu Li
In response to the overlooked influence of precursor molecular structure on interfacial performance in the application of amphiphilic carbon dots (CDs) for enhanced oil recovery (EOR), this study synthesized nitrogen-doped CDs (NCDs, FG, and TA series) using biomass-derived precursors via carbonization, amidation, quaternization, and alkylation. The relationships between precursor structure, surface functionality, interfacial behavior, and oil displacement performance were systematically investigated. TA-derived NCDs exhibited higher surface polarity and amphiphilicity due to abundant carboxyl groups, while increasing alkyl chain length enhanced hydrophobicity and suppressed surface defects. TA-NCDs-L16 showed the best interfacial properties, with a critical micelle concentration (CMC) of 0.104 g/L, γ CMC of 24.71 mN/m, and zeta potential of +67.80 mV. Under NaCl concentrations ranging from 0 to 12 wt%, the oil–water interfacial tension decreased to a minimum of 0.00151 mN/m, and the contact angle dropped to 16.3°, indicating excellent salt tolerance and wettability reversal capability. In low-permeability core flooding tests, TA-NCDs-L16 achieved a significantly enhanced final oil recovery of 60.42%, with a 27.26% increase in recovery and a 38.71% reduction in injection pressure. The improved EOR performance was attributed to ultra-low interfacial tension, the formation of high-density polar adsorption layers, and nanoscale size effects that enabled efficient pore-throat penetration and fluid redistribution, thereby facilitating the detachment and mobilization of residual oil. In high-salinity formation water containing Ca 2+ /Mg 2+ and under elevated temperatures (50–90 °C), further evaluation confirmed that the amphiphilic NCDs maintained strong interfacial activity and sustained wettability reversal. TA-NCDs-L16 retained an ultra-low interfacial tension (∼0.002 mN/m) and stable wettability regulation even after 240 h of thermal aging at 80 °C, while core flooding still exhibited significant reductions in injection pressure and enhancements in oil recovery. This study clarifies the correlation among precursor structure, functional group configuration, interfacial behavior, and oil displacement efficiency, providing theoretical guidance and material design concepts for the development of carbon-based amphiphilic nanofluids in low-permeability reservoir applications.
{"title":"Biomass-derived amphiphilic nitrogen-doped carbon dots: Molecular design, interfacial regulation, and enhanced oil recovery performance","authors":"Yu Wu, Yan-Cheng Zheng, Jian Mu, Fu-Chang You, Zheng-Yu Li","doi":"10.1016/j.petsci.2025.12.011","DOIUrl":"https://doi.org/10.1016/j.petsci.2025.12.011","url":null,"abstract":"In response to the overlooked influence of precursor molecular structure on interfacial performance in the application of amphiphilic carbon dots (CDs) for enhanced oil recovery (EOR), this study synthesized nitrogen-doped CDs (NCDs, FG, and TA series) using biomass-derived precursors via carbonization, amidation, quaternization, and alkylation. The relationships between precursor structure, surface functionality, interfacial behavior, and oil displacement performance were systematically investigated. TA-derived NCDs exhibited higher surface polarity and amphiphilicity due to abundant carboxyl groups, while increasing alkyl chain length enhanced hydrophobicity and suppressed surface defects. TA-NCDs-L16 showed the best interfacial properties, with a critical micelle concentration (CMC) of 0.104 g/L, γ CMC of 24.71 mN/m, and zeta potential of +67.80 mV. Under NaCl concentrations ranging from 0 to 12 wt%, the oil–water interfacial tension decreased to a minimum of 0.00151 mN/m, and the contact angle dropped to 16.3°, indicating excellent salt tolerance and wettability reversal capability. In low-permeability core flooding tests, TA-NCDs-L16 achieved a significantly enhanced final oil recovery of 60.42%, with a 27.26% increase in recovery and a 38.71% reduction in injection pressure. The improved EOR performance was attributed to ultra-low interfacial tension, the formation of high-density polar adsorption layers, and nanoscale size effects that enabled efficient pore-throat penetration and fluid redistribution, thereby facilitating the detachment and mobilization of residual oil. In high-salinity formation water containing Ca 2+ /Mg 2+ and under elevated temperatures (50–90 °C), further evaluation confirmed that the amphiphilic NCDs maintained strong interfacial activity and sustained wettability reversal. TA-NCDs-L16 retained an ultra-low interfacial tension (∼0.002 mN/m) and stable wettability regulation even after 240 h of thermal aging at 80 °C, while core flooding still exhibited significant reductions in injection pressure and enhancements in oil recovery. This study clarifies the correlation among precursor structure, functional group configuration, interfacial behavior, and oil displacement efficiency, providing theoretical guidance and material design concepts for the development of carbon-based amphiphilic nanofluids in low-permeability reservoir applications.","PeriodicalId":506739,"journal":{"name":"Petroleum Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In situ plugging hydrogels represent a promising strategy to combat wellbore instability in fractured formations. Despite their potential, they often fail due to unpredictable gelation kinetics and inadequate mechanical strength under downhole conditions. Here, we introduce an alginate-based hydrogel (Alg-gel) engineered with an acid-triggered, multi-crosslinking mechanism that constructs a biodegradable shield directly within fractures. This system integrates sodium alginate (SA) with hydroxypropyl guar gum (Hpg) to form a primary semi-interpenetrating network. The critical innovation lies in the synergistic use of D-gluconic-δ-lactone (GDL) and CaCO 3 , which enables precise, sustained release of Ca 2+ ions. These ions subsequently coordinate with guluronate blocks in SA, establishing a secondary network that embeds residual CaCO 3 as reinforcing scaffolds. This multi-network architecture results in a storage modulus increase by orders of magnitude and reduces filtration loss by up to 89.3% as gelation proceeds from 30 to 180 minutes. Structural evolution from a sparse framework to a densely interlocked lamellar assembly was directly visualized, validating the tunable nature of the complexation process. The exceptional plugging performance and controllable gelation kinetics position Alg-gel as a superior lost circulation material, with broader implications for profile modification and gas channeling mitigation.
{"title":"Synergistic alginate chelation and semi-interpenetrating network for advanced wellbore stabilizing hydrogels","authors":"Zhaojie Wei, Yuhua Duan, Maosen Wang, Yinghui An, Wenjing Qin, Mingyi Guo","doi":"10.1016/j.petsci.2025.11.030","DOIUrl":"https://doi.org/10.1016/j.petsci.2025.11.030","url":null,"abstract":"In situ plugging hydrogels represent a promising strategy to combat wellbore instability in fractured formations. Despite their potential, they often fail due to unpredictable gelation kinetics and inadequate mechanical strength under downhole conditions. Here, we introduce an alginate-based hydrogel (Alg-gel) engineered with an acid-triggered, multi-crosslinking mechanism that constructs a biodegradable shield directly within fractures. This system integrates sodium alginate (SA) with hydroxypropyl guar gum (Hpg) to form a primary semi-interpenetrating network. The critical innovation lies in the synergistic use of D-gluconic-δ-lactone (GDL) and CaCO 3 , which enables precise, sustained release of Ca 2+ ions. These ions subsequently coordinate with guluronate blocks in SA, establishing a secondary network that embeds residual CaCO 3 as reinforcing scaffolds. This multi-network architecture results in a storage modulus increase by orders of magnitude and reduces filtration loss by up to 89.3% as gelation proceeds from 30 to 180 minutes. Structural evolution from a sparse framework to a densely interlocked lamellar assembly was directly visualized, validating the tunable nature of the complexation process. The exceptional plugging performance and controllable gelation kinetics position Alg-gel as a superior lost circulation material, with broader implications for profile modification and gas channeling mitigation.","PeriodicalId":506739,"journal":{"name":"Petroleum Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nanofluids are considered promising agents for enhanced oil recovery in low-permeability reservoirs, but their application is often restricted by poor thermal and saline resistance and high costs. Moreover, limited studies have addressed the imbibition depth and oil migration processes during nanofluid imbibition in low-permeability reservoirs. In this work, a magnetic core–shell structured nanoparticle Fe 3 O 4 -TiO 2 was synthesized using inexpensive Fe 3 O 4 nanoparticles and tetrabutyl titanate. The synthesized nanoparticles exhibited excellent thermal and saline resistance as well as recyclability. Their structure and functional properties were characterized. The nuclear magnetic resonance technology was applied to investigate the imbibition depth and the oil migration process during magnetic nanofluid imbibition. Results showed that the magnetic nanofluid possessed interfacial activity, wettability alteration capability, and strong thermal and saline resistance. At 80 °C, the imbibition recovery of magnetic nanofluid reached 32.19%, 3.59% higher than that of SiO 2 nanofluid. The recycle rate of magnetic nanofluid was 81.31%, effectively reducing operational costs. The final imbibition depth of magnetic nanofluid reached 18.82 mm, with an average imbibition rate of 3.14 mm/d, which is 21.97% higher than that of the SiO 2 nanofluid and 39.10% higher than that of the simulated formation water. The imbibition process of magnetic nanofluid was dominated by capillary forces, with oil in micropores displaced into macropores. We expect that this study can contribute to the effective development of low-permeability reservoirs and provide theoretical guidance for field applications.
{"title":"Experimental study of imbibition depth and oil migration mechanism of a magnetic nanofluid for low-permeability reservoir oil recovery improvement","authors":"Zhenfeng Ma, Mingwei Zhao, Xiangyu Wang, Kai-Wen Liu, Yuxin Xie, Yizheng Zhang, Zhongzheng Xu, Caili Dai","doi":"10.1016/j.petsci.2025.11.026","DOIUrl":"https://doi.org/10.1016/j.petsci.2025.11.026","url":null,"abstract":"Nanofluids are considered promising agents for enhanced oil recovery in low-permeability reservoirs, but their application is often restricted by poor thermal and saline resistance and high costs. Moreover, limited studies have addressed the imbibition depth and oil migration processes during nanofluid imbibition in low-permeability reservoirs. In this work, a magnetic core–shell structured nanoparticle Fe 3 O 4 -TiO 2 was synthesized using inexpensive Fe 3 O 4 nanoparticles and tetrabutyl titanate. The synthesized nanoparticles exhibited excellent thermal and saline resistance as well as recyclability. Their structure and functional properties were characterized. The nuclear magnetic resonance technology was applied to investigate the imbibition depth and the oil migration process during magnetic nanofluid imbibition. Results showed that the magnetic nanofluid possessed interfacial activity, wettability alteration capability, and strong thermal and saline resistance. At 80 °C, the imbibition recovery of magnetic nanofluid reached 32.19%, 3.59% higher than that of SiO 2 nanofluid. The recycle rate of magnetic nanofluid was 81.31%, effectively reducing operational costs. The final imbibition depth of magnetic nanofluid reached 18.82 mm, with an average imbibition rate of 3.14 mm/d, which is 21.97% higher than that of the SiO 2 nanofluid and 39.10% higher than that of the simulated formation water. The imbibition process of magnetic nanofluid was dominated by capillary forces, with oil in micropores displaced into macropores. We expect that this study can contribute to the effective development of low-permeability reservoirs and provide theoretical guidance for field applications.","PeriodicalId":506739,"journal":{"name":"Petroleum Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.petsci.2025.11.025
Tao Yin, Yao Zhu, Yuqi Yang, S. S. Chen, J.J. Chen, Yuanyuan Lü, Han-Yu Guo, Tao Wan, Jian Liu
Temporary plugging agents are critical to oilfield operations such as diversion fracturing, wellbore interventions, and drilling. This study develops a double-crosslinked self-degradable gel (DSDG) using polydopamine and poly(ethylene glycol) diacrylate as crosslinkers for polyacrylamide, targeting low temperature reservoirs. The DSDG system integrates covalent crosslinking via C=C bonds and dynamic crosslinking through amine–catechol interactions. Gelation kinetics, rheological properties, self-degradation mechanisms, and gel breaking performance of DSDG were systematically characterized. By analyzing the influence of components on gelation kinetics and mechanical properties, the composition of DSDG was optimized to include 4–8 wt% acrylamide monomer, 0.5–0.8 wt% initiator, and 0.2–0.6 wt% poly(ethylene glycol) diacrylate crosslinker, with a dopamine to acrylamide mass ratio of (5–8) × 10 −3 . At 60–80 °C, DSDG transitions from liquid to quasi-solid gel within 30–180 min, with > 80% of the gelation process occurring in a low viscosity phase conducive to pumpable injection. Unoxidized catechol groups, π–π stacking, and hydrogen bonding synergistically enhance tensile strength, fracture toughness, and interfacial adhesion, enabling robust sealing under downhole stresses. Core flooding tests in 5–50 mD cores achieved initiation and breakthrough pressure gradients of 34.6–119 and 86.6–184.6 MPa/m, respectively. In simulated wellbore with an inner diameter of 120 mm, the pressure-bearing capacity reached 1.25 MPa/m. Acidic/alkaline conditions rapidly degrade polydopamine, disrupting network integrity and enabling controllable gel breaking times of 1–20 d. Free dopamine monomers inhibit acrylamide polymerization, reducing post-degradation viscosity to < 10 mPa·s via shortened polyacrylamide chains.
{"title":"Double-crosslinked self-degradable hydrogel for temporary plugging in low temperature reservoirs","authors":"Tao Yin, Yao Zhu, Yuqi Yang, S. S. Chen, J.J. Chen, Yuanyuan Lü, Han-Yu Guo, Tao Wan, Jian Liu","doi":"10.1016/j.petsci.2025.11.025","DOIUrl":"https://doi.org/10.1016/j.petsci.2025.11.025","url":null,"abstract":"Temporary plugging agents are critical to oilfield operations such as diversion fracturing, wellbore interventions, and drilling. This study develops a double-crosslinked self-degradable gel (DSDG) using polydopamine and poly(ethylene glycol) diacrylate as crosslinkers for polyacrylamide, targeting low temperature reservoirs. The DSDG system integrates covalent crosslinking via C=C bonds and dynamic crosslinking through amine–catechol interactions. Gelation kinetics, rheological properties, self-degradation mechanisms, and gel breaking performance of DSDG were systematically characterized. By analyzing the influence of components on gelation kinetics and mechanical properties, the composition of DSDG was optimized to include 4–8 wt% acrylamide monomer, 0.5–0.8 wt% initiator, and 0.2–0.6 wt% poly(ethylene glycol) diacrylate crosslinker, with a dopamine to acrylamide mass ratio of (5–8) × 10 −3 . At 60–80 °C, DSDG transitions from liquid to quasi-solid gel within 30–180 min, with > 80% of the gelation process occurring in a low viscosity phase conducive to pumpable injection. Unoxidized catechol groups, π–π stacking, and hydrogen bonding synergistically enhance tensile strength, fracture toughness, and interfacial adhesion, enabling robust sealing under downhole stresses. Core flooding tests in 5–50 mD cores achieved initiation and breakthrough pressure gradients of 34.6–119 and 86.6–184.6 MPa/m, respectively. In simulated wellbore with an inner diameter of 120 mm, the pressure-bearing capacity reached 1.25 MPa/m. Acidic/alkaline conditions rapidly degrade polydopamine, disrupting network integrity and enabling controllable gel breaking times of 1–20 d. Free dopamine monomers inhibit acrylamide polymerization, reducing post-degradation viscosity to < 10 mPa·s via shortened polyacrylamide chains.","PeriodicalId":506739,"journal":{"name":"Petroleum Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Black nanosheets (BN, with a specific chemical composition of molybdenum disulfide) have been widely studied for low-permeability reservoir development due to their unique nanoscale dimensions and lamellar structure. Our prior research demonstrated that cationically modified BN combined with low-salinity water (LSW) significantly enhances oil displacement. This study compared the imbibition adaptability of the composite system under both ambient-pressure and pressurized conditions, while combining nuclear magnetic resonance (NMR) techniques to analyze related imbibition mechanisms and reservoir permeability adaptability. Results showed that the modified BN-LSW composited system achieved an imbibition recovery efficiency of 43.92% under ambient pressure. The mechanism was capillary force-dominated, preferentially displacing oil from small pores by improving core wettability and emulsification. Under pressurized conditions, the driving force became dominant, further increasing recovery efficiency to 56.52%, with the system displacing oil from both large and small pores. Additionally, the system showed optimal adaptability in cores with 0.05 × 10 −3 μm 2 permeability. Imbibition efficiency declined at higher/lower permeabilities due to weakened capillary forces or nanoparticle aggregation-induced clogging. This study confirmed that the modified BN-LSW composite system enhanced imbibition stability and recovery efficiency, and combined with nuclear magnetic resonance (NMR) technology, its mechanism was revealed at the microscale. This provided theoretical and technical support for the efficient development of low-permeability reservoirs, with significant engineering value.
{"title":"Imbibition mechanism analysis of modified black nanosheet and low salinity water composite system for enhanced oil recovery by NMR method","authors":"S.Y. Guo, Jiong Zhang, Yang Gao, Hiangkiat Tan, Hongbin Cheng, Hongyu Li, Daoyi Zhu","doi":"10.1016/j.petsci.2025.08.026","DOIUrl":"https://doi.org/10.1016/j.petsci.2025.08.026","url":null,"abstract":"Black nanosheets (BN, with a specific chemical composition of molybdenum disulfide) have been widely studied for low-permeability reservoir development due to their unique nanoscale dimensions and lamellar structure. Our prior research demonstrated that cationically modified BN combined with low-salinity water (LSW) significantly enhances oil displacement. This study compared the imbibition adaptability of the composite system under both ambient-pressure and pressurized conditions, while combining nuclear magnetic resonance (NMR) techniques to analyze related imbibition mechanisms and reservoir permeability adaptability. Results showed that the modified BN-LSW composited system achieved an imbibition recovery efficiency of 43.92% under ambient pressure. The mechanism was capillary force-dominated, preferentially displacing oil from small pores by improving core wettability and emulsification. Under pressurized conditions, the driving force became dominant, further increasing recovery efficiency to 56.52%, with the system displacing oil from both large and small pores. Additionally, the system showed optimal adaptability in cores with 0.05 × 10 −3 μm 2 permeability. Imbibition efficiency declined at higher/lower permeabilities due to weakened capillary forces or nanoparticle aggregation-induced clogging. This study confirmed that the modified BN-LSW composite system enhanced imbibition stability and recovery efficiency, and combined with nuclear magnetic resonance (NMR) technology, its mechanism was revealed at the microscale. This provided theoretical and technical support for the efficient development of low-permeability reservoirs, with significant engineering value.","PeriodicalId":506739,"journal":{"name":"Petroleum Science","volume":"22 12","pages":"5166-5175"},"PeriodicalIF":0.0,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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