Preparation And Properties Of Salt Resistance Drag Reduction Agent

A large amount of return liquid is generated during the fracturing operation of the shale gas field,and the treatment of the return liquid is a problem in the fracturing operation.At present,the widely used solution is to add drag reducing agent to the drag reducing water fracturing fluid after the back drainage treatment to continue the fracturing operation.Therefore,the salt resistance of polyacrylamide drag reducer was improved by preparing hydrophobically associating polyacrylamide and cationic polyacrylamide microspheres hydrolyzed /polyacrylamide composite system.The paper uses methyl methacrylate(MMA)as a hydrophobically modified monomer,2-acrylamido-2-methylpropanesulfonic acid(AMPS)as a salt-resistant monomer,by inverse emulsion polymerization with acrylamide,acrylic acid.The content of emulsifier,the size of HLB,the main monomer AM/AA ratio,the water monomer concentration,the hydrophobic modified monomer MMA content,the initiator content,and the functional monomer AMPS content were optimized.The structure characterization proved that P(AM/AA/AMPS/MMA)hydrophobic associates were synthesized.The influence of various factors on apparent viscosity was as follows: mass percentage of MMA > mass percentage of AMPS > the main monomer AM/AA ratio > HLB value > initiator > monomer concentration.It can be seen from scanning electron microscopy that when the concentration of polymer solution exceeds the critical association concentration of CAC,the solution has formed a unique spatial network structure due to the hydrophobic association effect of hydrophobic groups.In salt solution with concentration of 3 g/L,the polymer concentration changed from 0.8 g/L to 1.0g/L,the apparent viscosity of the solution increased sharply,and the apparent viscosity of the solution changed from 2.8 m Pa·s to 4.6 m Pa·s.The composition,particle size,size distribution and morphology of the samples were characterized and evaluated by Fourier transform infrared spectroscopy(FT-IR),dynamic light scattering laser particle size analyzer(DLS)and cold field scanning electron microscopy(SEM).The results show that the particle size of the cationic polyacrylamide microspheres and the molecular weight of the hydrolyzed polyacrylamide(HPAM)and the salt solution have a great influence on the performance of the compounding system.In salt solution with concentration of 3 g/L,the composite system of HPAM with molecular weight of 20 million and cationic polyacrylamide microspheres with nano-scale has viscosifying effect.The flocculation system of the microspheres and HPAM is expected to be used to dispose slippery water in high salinity fracturing fluid.