Research On Synthesis Of Low-molecular Clean Fracturing Fluid

In recent years,with the continuous development of social productivity,all countries are seeking to pursue a more reasonable exploration and development of oil and gas fields.In the process of exploration and development of oil and gas fields,hydraulic fracturing can play a positive role in improving oil and gas production and recovery,and the performance of fracturing fluid is the key to fracturing operation.Low molecular clean fracturing fluid has good temperature resistance,shear resistance,rheological properties,low filtration properties and low damage characteristics.Therefore,low molecular polymer is used as thickener and organic zirconium as crosslinker to study the synthesis of low molecular clean fracturing fluid.The reaction time is 6 hours,the reaction temperature is 50,the pH value is 6,the total mass concentration of the monomer is 20%,and the mass ratio of the monomer is AM:AA:AMPS:Twelve alkyl allyl ammonium chloride is 10:2:1.4:1;the mass of the initiator is 0.6%of the total mass,of which the content ratio of ammonium persulfate to Sodium Bisulfite is 2:1.A copolymer of four elements has been polymerized as a low molecular fracturing fluid through the above conditions,and its color is even grainy,which achieves the requirements of performance and appearance index.After molecular weight determination,the molecular weight of thickener is about 250 thousand,which is only 1/10 of the molecular weight of guar gum.The final product of the thickener was analyzed by Fourier transform infrared spectroscopy,which showed that the final product of the synthesis was a four-element copolymer thickener.The synthesis condition is monomer mass ratio:zirconium oxychloride:isopropyl alcohol:glycerol:sodium lactate ?1:3.75:1.25:0.1875,pH value is 6.7-7.3.The synthesized zirconium crosslinking agent has the best gelation time and temperature resistance ability,and achieves the synergistic cross-linking and controlling cross-linking time.The final product of the crosslinking agent was analyzed by Fourier transform infrared spectroscopy,which showed that the final product of the synthesis was organic zirconium crosslinker.In four the copolymerization of fused agent and organic zirconium crosslinking agent on the basis of the research,optimization of the low molecular components of clean fracturing fluid has been completed,preliminary established at three different temperatures and low temperature,medium temperature and low molecular formula of high temperature fracturing fluid system.Low temperature formula:four copolymer thickener 0.2%+ organic zirconium crosslinking agent 0.14%+ organic amine 2.0%+ clay stabilizer additive JFC0.2%;medium temperature formula:four copolymer thickener 0.4%+ organic zirconium crosslinking agent 0.28%+ organic amine 2.0%+ clay stabilizer additive JFC0.2%;high temperature formula:four copolymer thickener 0.6%+ organic zirconium crosslinkuing agent 0.42%+ organic amine clay stabilizer 2.0%+ cleanup agent JFC 0.2%.The evaluation results show that low molecular clean fracturing fluid shear stability,rheological properties,suspended sand properties,viscoelastic properties,gel breaking flowback performance,good filtration capacity,breaking the residue is low;the reservoir core damage is small,suitable for low permeability oil and gas fracturing operation.