Synthesis And Performance Evaluation Of AM / AMPS / DM-16 Hydrophobic Associated Polymer Fracturing Fluid Thickener

Hydraulic fracturing is an important method to increase oil and gas production. Fracturing fluids which could delivery pressure, transport proppants, create the new fissure in formation play a key role in the process of fracturing. Hydrophobic monomer (DM-16) which could meet the basic requirements of fracturing fluids and the rule of molecular designing was synthetized. The results of the infrared characterization and nuclear magnetic resonance spectrometer confirmed that the structure of the product is consistent with the original design. The productive rate could reach90.6%which is high enough. The CMC (critical micelle concentration) was0.035mmol·L-1and the surface tension is30mN/m when it is CMC which shows good surface activity.Hydrophobic monomer (DM-16), Acrylamide (AM),2-acrylamido-2-methyl propane sulfonic acid (AMPS) were chosen to be the final monomers. The optimum conditions determined by single factor analysis are that temperature of reaction is50℃, monomer mass is20%, molar ratio of monomer n (AM):n(AMPS):n(DM-16) is75:23.8:1.2, dosage of initiator is0.2%, pH is7,reaction time is5h. The results of the IR,NMR and Elemental Analyzer confirmed the structure of the product is consistent with the original design. The properties of polymer solution are evaluated. The CAC is0.4g-dL-1. The viscosity could stay30mPa-s when it is90℃which shows high temperature resistance. It showed different phenomenon when NaCl and CaCl2was separately mixed with the polymer, which was led by the difference between Na+and Ca2+.The retention rate of viscosity could reach85.5%after2h at170S-1. The viscosity starts with55mPa-s and ends with47mPa-s. The results of SDS and SDBS mixed with the polymer showed that the viscosity would increase until it reached the top, then the viscosity would decrease. Through SEM results,we found the micelle was the reason why the viscosity increased.Glutaraldehyde and zirconium acetylacetonate are chosen to form a compound formula as crosslinking agent. Temperature and pH are analysed to study their effect on the crosslinking in order to get the final formula. Glutaraldehyde and zirconium acetylacetonate’s mass is0.075%. pH is2.The optimum formula is0.5%polymer as thicker,0.075%Glutaraldehyde and0.075%zirconium acetylacetonate as crosslinker,0.1%-0.3%Na2S2O3as temperature stablizer0.01%-0.1%K2S2O8as gel breaker,1%-3%KCl as clay stabilizer,0.5%WD-12as clean up additive.The fracturing fluids properties are tested. The rheometer results show that fracturing fluid has good viscoelastic, rheological parameter’η’is0.23,’κ’is19.49.Between0.1Hz and10Hz, the storage modulus G’is greater than the energy consumption modulus G" which also proved that the fluids is good at transporting proppants. When it was125℃, the viscosity could remain50mPa-s which shows that the fracturing fluid could be used under125℃.The viscosity didn’t change so much after1.5h at170S-1which showed that the fluid could resist shearing. The gel breaking result showed that the fluid viscosity is less than10mPa-s, the surface tension is less than36mN/m, the interfacial tension3.4mN/m and the sludge content is less than73mg/L,all the data could meet the demand of low polymer fracturing fluids.