| With the continuous development of the oil industry,people set their sights on low permeability reservoirs which cannot be easily exploited in regard of the later period of oil and gas field development.In order to increase the production of oil and gas fields,low permeability reservoirs which have low permeability,less oil production,high well pressure and other shortcomings must be exploited by means of artificial fracturing?fracturing fluid?.So its performance is directly related to the stand or fall of fracturing.At present,hydraulic fracturing is commonly used as a means of fracturing.But it has some shortcomings,such as the large apparent viscosity,slow dissolution rate,poor heat resistance performance and et.al,which cause inconvenience of transport and construction.The synthesis of fracturing fluid with low apparent viscosity,rapid dissolution and good heat resistance performance has become a focus recently.In this paper,five hydrophobic monomers M1 of different chain lengths were pre pared by quaternization of dimethylaminoethyl methacrylate and Bromoethane,1-Bromo butane,1-Bromododecane,1-Bromohexadecane,1-Bromooctadecane respectively.Steric hindered monomer S?4-acryloyl amino benzene sulfonate?were prepared by chloroform ylation reaction sulfanilic acid and acrylyl chloride.Hydrophobic monomer M2?allyldi methyldodecylammonium chloride?was prepared by quaternization of N,N-Dimethylocta decylamine and Allyl chloride.Finally,the structures of synthesized compounds were c haracterized by NMR and FTIR.According to the requirements of structures of fracturing fluid and synthetic reaction conditions of inverted emulsion polymerization,this paper chose Acrylamide?AM?as hydrophilic monomer,2-Acrylamide-2-methylpropanesulfonic acid?AMPS?as temperature and salt resistance monomer,hydrophobic monomer M1 and steric hindered monomer S as internal phase,white oil as organic phase,Span 80 and Tween 80 as compound emulsifier,heat-resisting hydrophobically associating polymer AAMS-1 was prepared by inverse emulsion polymerization.In order to obtain a stable emulsion system,the best polymerization conditions were obtained by changing the ratio of oil and water,mixing time and emulsification time.The result showed that hydrophobic chain length of 12 had an obvious association reaction after studying the hydrophobic monomers of different chain lengths.When the hydrophobic monomer molar content was 0.8 wt%and chain length was 18,the viscosity of 0.6 wt%aqueous solution reached 916 mPa·s.To further examine the performance of 0.6 wt%aqueous which used as fracturing fluid,it was purified firstly and characterized by FTIR.It was stable under 250?,which revealed by Thermal Gravity Analysis?TGA?.The average latex particle size was around 2000 nm by laser particle size analysis and the critical associating concentration?CAC?of the AAMS-1solution was found to be about 0.15wt%.The network structures of five-membered ring were observed by Scanning Electron Microscope?SEM?.The viscosity of 0.6 wt%fracturing fluid remained above 50 mPa·s at 150?and 170 S-1 after 2 h.After evaluating its viscoelasticity,it was found that gel breaking and core damage properties were all in compliance with the water-based fracturing fluid standard.Association of hydrophobic monomers is of great importance to the fracturing fluid.Then,a hydrophobic associating polymer AAMS-2 was obtained by polymerization of a hydrophobic monomer M2.It was purified and then characterized by FTIR.It was quite stable at 242?,which revealed byTGA.The average latex particle size was around 2000 nm by laser particle size analyze and the critical associating concentration?CAC?of the AAMS-1 solution was found to be about 0.16 wt%.The formation of ring network structure was observed by SEM.The viscosity of 0.6 wt%aqueous solution reached to 574 mPa·s.By testing the performance under high temperature and shear resistance,0.6wt%aqueous solution had good viscoelasticity,gel breaking and core damage properties at 150?of formation. |
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