Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has ...Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has been widely reported that the effectiveness and efficiency of water shutoff using gel is mostly dependent on the gel dynamic sealing properties in the porous media.Firstly the gelation strength and gelation time of polymer gel were evaluated.Then,core flowing experiments were conducted before and after gelation in a 32 m long sand pack.In addition,water flooding core experiments were also carried out in a long core of 80 cm before and after injecting gel system to check the reliability of this evaluation method.The experimental results show that moderate-strength gel can be formed at 65 °C.According to the integrated evaluation of the plugging coefficient,plugging strength and water breakthrough time,the gel particles are capable of migrating to a distance of 7.47 m from the injection point of the 32 m long sand pack during the water injection process after gelation.Based on sands gelation status and effluent analyses,the effective migration distance of the gel particles is 4-14 m.Through the core flooding experiments using the 80 cm heterogeneous core,it is evidenced that the gel can be formed in the deep reservoir(40.63% of total length) with the plugging strength as high as 6.33 MPa/m,which leads to extra oil recovery of 10.55% of original oil in place(OOIP) by water flooding after gel treatment.展开更多
With high water content(～90 wt%) and significantly improved mechanical strength(～MPa),double network(DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,D...With high water content(～90 wt%) and significantly improved mechanical strength(～MPa),double network(DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,DN hydrogels with extremely high mechanical strength have achieved great advance,and scientists have designed a series of natural and biomimetic DN hydrogels with novel functions including low friction,low wear,mechanical anisotropy and cell compatibility.These advances have also led to new design of biocompatible DN hydrogels for regeneration of tissues such as cartilage.In this paper,we reviewed the strategies of designing high-strength DN hydrogel and analyzed the factors that affect DN hydrogel properties.We also discussed the challenges and future development of the DN hydrogel in view of its potential as biomaterials for their biomedical applications.展开更多
Constructing high strength pH sensitive supramolecular polymer hydrogel remains very challenging due to the unavoidable network swelling caused by ionization of acid or basic groups at a specified pH.In this work,we p...Constructing high strength pH sensitive supramolecular polymer hydrogel remains very challenging due to the unavoidable network swelling caused by ionization of acid or basic groups at a specified pH.In this work,we proposed a simple and very convenient approach to fabricate high strength pH responsive supramolecular polymer(SP) hydrogels by one-pot copolymerization of N-acryloyl glycinamide(NAGA) and 2-vinyl-4,6-diamino-1,3,5-triazine(VDT),two feature hydrogen bonding monomers.In these PNAGA-PVDT SP hydrogels obtained,the hydrogen bonding of NAGA was shown to play a dominant role in reinforcing strength,while the hydrogen bonding of diaminotriazine served as a pH sensitive moiety.At pH 3,the mechanical properties of PNAGA-PVDT hydrogels decreased to a different extent due to the breakup of hydrogen bonding;in contrast,the hydrogel resumed the original strength while pH was raised to 7.4 because of reconstruction of hydrogen bonding.Over the selected pH range,the PNAGA-PVDT hydrogels exhibited up to 1.25 MPa tensile strength,845% breaking strain,69 kPa Young's modulus and 21 MPa compressive strength.This novel high strength pH-responsive SP hydrogels may find applications in biomedical and industrial fields.展开更多
To correct the defects of hydrophobic association hydrogels （HA-gels）, new physically and chemically cross-linked hybrid hy- drophobic association hydrogels （hybrid HA-gels） were prepared by radical copolymerizati...To correct the defects of hydrophobic association hydrogels （HA-gels）, new physically and chemically cross-linked hybrid hy- drophobic association hydrogels （hybrid HA-gels） were prepared by radical copolymerization of acrylamide （AM）, octylphe- nol polyoxyethylene （n） acrylate （OPnAC, n stands for the number of ethoxy group, and is 10 and 21） and N,N＇-methylene- bisacrylamide （MBA）. On the basis of the statistical molecular theory of rubber elastic, the Mooney-Rivlin model and using the tensile true stress （O＇true） tested at room temperature, the number of network strands per unit volume （o~） and the num- ber-average molar mass of a network strand （Me） were evaluated for hybrid HA-gels. For the hydrogels, the effect of the con- tent of MBA and OP10AC on their tensile mechanical properties was studied by using o0 and Mc; also, the effect of the com- positions and temperature on their swelling behavior in distilled water was discussed in detail. In addition, hybrid HA-gels in- cluding a small quantity of MBA possessed the capabilities of secondary self-healing and remolding. In contrast with HA-gels prepared by the same compositions besides MBA, hybrid HA-gels showed good mechanical strength and long-term thermal stability in distilled water in the range of 25 to 80℃. Furthemore, hybrid HA-gels also avoided the self-deswelling behavior of HA-gels. The results show that the application fields of HA-gels will be greatly broadened after introducing a chemical cross-linking network.展开更多
基金Project(2011ZX05009-004)supported by the National Significant Science and Technology Program of China
文摘Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has been widely reported that the effectiveness and efficiency of water shutoff using gel is mostly dependent on the gel dynamic sealing properties in the porous media.Firstly the gelation strength and gelation time of polymer gel were evaluated.Then,core flowing experiments were conducted before and after gelation in a 32 m long sand pack.In addition,water flooding core experiments were also carried out in a long core of 80 cm before and after injecting gel system to check the reliability of this evaluation method.The experimental results show that moderate-strength gel can be formed at 65 °C.According to the integrated evaluation of the plugging coefficient,plugging strength and water breakthrough time,the gel particles are capable of migrating to a distance of 7.47 m from the injection point of the 32 m long sand pack during the water injection process after gelation.Based on sands gelation status and effluent analyses,the effective migration distance of the gel particles is 4-14 m.Through the core flooding experiments using the 80 cm heterogeneous core,it is evidenced that the gel can be formed in the deep reservoir(40.63% of total length) with the plugging strength as high as 6.33 MPa/m,which leads to extra oil recovery of 10.55% of original oil in place(OOIP) by water flooding after gel treatment.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51073127,51173144 )the Higher School Specialized Research Fund for the Doctoral Program FundingIssue (Grant No. 20100201110040 )+1 种基金the Operation Expenses for Universities’ Basic Scientific Research of Central Authorities (Grant No. 0109-08140018 )the New Research Support Project (Grant No. 08141001) from Xi’an Jiaotong University,P. R. China
文摘With high water content(～90 wt%) and significantly improved mechanical strength(～MPa),double network(DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,DN hydrogels with extremely high mechanical strength have achieved great advance,and scientists have designed a series of natural and biomimetic DN hydrogels with novel functions including low friction,low wear,mechanical anisotropy and cell compatibility.These advances have also led to new design of biocompatible DN hydrogels for regeneration of tissues such as cartilage.In this paper,we reviewed the strategies of designing high-strength DN hydrogel and analyzed the factors that affect DN hydrogel properties.We also discussed the challenges and future development of the DN hydrogel in view of its potential as biomaterials for their biomedical applications.
基金supported by the National Natural Science Foundation of China(Grant No.51325305)National Key Research and Development Program(GrantNo.2016YFC1101301)Tianjin Municipal Natural Science Foundation(Grant Nos.13ZCZDSY00900,15JCZDJC38000)
文摘Constructing high strength pH sensitive supramolecular polymer hydrogel remains very challenging due to the unavoidable network swelling caused by ionization of acid or basic groups at a specified pH.In this work,we proposed a simple and very convenient approach to fabricate high strength pH responsive supramolecular polymer(SP) hydrogels by one-pot copolymerization of N-acryloyl glycinamide(NAGA) and 2-vinyl-4,6-diamino-1,3,5-triazine(VDT),two feature hydrogen bonding monomers.In these PNAGA-PVDT SP hydrogels obtained,the hydrogen bonding of NAGA was shown to play a dominant role in reinforcing strength,while the hydrogen bonding of diaminotriazine served as a pH sensitive moiety.At pH 3,the mechanical properties of PNAGA-PVDT hydrogels decreased to a different extent due to the breakup of hydrogen bonding;in contrast,the hydrogel resumed the original strength while pH was raised to 7.4 because of reconstruction of hydrogen bonding.Over the selected pH range,the PNAGA-PVDT hydrogels exhibited up to 1.25 MPa tensile strength,845% breaking strain,69 kPa Young's modulus and 21 MPa compressive strength.This novel high strength pH-responsive SP hydrogels may find applications in biomedical and industrial fields.
文摘To correct the defects of hydrophobic association hydrogels （HA-gels）, new physically and chemically cross-linked hybrid hy- drophobic association hydrogels （hybrid HA-gels） were prepared by radical copolymerization of acrylamide （AM）, octylphe- nol polyoxyethylene （n） acrylate （OPnAC, n stands for the number of ethoxy group, and is 10 and 21） and N,N＇-methylene- bisacrylamide （MBA）. On the basis of the statistical molecular theory of rubber elastic, the Mooney-Rivlin model and using the tensile true stress （O＇true） tested at room temperature, the number of network strands per unit volume （o~） and the num- ber-average molar mass of a network strand （Me） were evaluated for hybrid HA-gels. For the hydrogels, the effect of the con- tent of MBA and OP10AC on their tensile mechanical properties was studied by using o0 and Mc; also, the effect of the com- positions and temperature on their swelling behavior in distilled water was discussed in detail. In addition, hybrid HA-gels in- cluding a small quantity of MBA possessed the capabilities of secondary self-healing and remolding. In contrast with HA-gels prepared by the same compositions besides MBA, hybrid HA-gels showed good mechanical strength and long-term thermal stability in distilled water in the range of 25 to 80℃. Furthemore, hybrid HA-gels also avoided the self-deswelling behavior of HA-gels. The results show that the application fields of HA-gels will be greatly broadened after introducing a chemical cross-linking network.
