Synthesis Optimization And Performance Evaluation Of Selective Plugging Chemicals

The exploitation of the domestic oil fields has entered the middle and late stage,and the average rate of produced fluid in oil wells is high.At present,the selective water shut-off operations is one of the important ways to solve this problem.In this paper,based on the original selective plugging chemicals(PAS)and combined with the experience of industrial production and the feedback data of application,the synthesis of the selective water shut-off agent was optimized,and the performance evaluation and construction technology were studied,finally,with the introduction of molecular simulation,the polymerization kinetics of acrylamide(AM)was calculated.The difference between the industrial monomer and pure monomer DMDAAC and its influence on the performance of plugging agent were studied,the results showed there were some impurities in the industrial monomer DMDAAC,which has little effect on the oil and water selection performance of plugging agent,then the dosage of industrial monomer DMDAAC and ammonium persulfate were optimized,and the results showed that the most appropriate molar ratio of monomer DMDAAC to total monomer was 4.94%.In addition,the dosage of initiator was optimized,and the experimental results showed that the most appropriate weight ratio of the ammonium persulfate to total monomer was 0.22%.The results of infrared spectrum analysis showed that the molecular structure of the plugging agent had the characteristic peaks in the spectrum,and the results of the pyrolysis gas chromategraphy mass spectrometry showed that the polymerization method of the blocking agent was copolymerizationThe performances of the optimized plugging agent were evaluated,including adsorption,temperature resistance,erosion resistance and oil-water selectivity.The test results showed that the adsorption performance of the optimized plugging agent was better than that of HPAM on the surface of quartz sand and formation sand;The optimized plugging agent could maintain the solution viscosity at 70℃ for 75 hours and the good adsorption performance on the surface of quartz sand and formation sand at 120℃;Blocked formation could endure water erosion for 20 PV,and the water permeability didn’t restore;And the plugging rate to water phase and oil phase were 72.15% and 17.92%,which indicated good oil-water selectivity.The construction processes of the optimized plugging agent were studied,including the effect of injected water,oil sand,pre-treatment measures and the length of sand filled pipe on the performance of the plugging agent.The results showed that the brine and oil sands could lead to a significant drop in oil and water selectivity of plugging agent,Before the plugging agent was injected into the oil sands,the surfactant could be used to recover the performance of the plugging agent,and the length of sand filling tube has limited effect on the plugging performance.The molecule simulation technology was used to calculate the polymerization kinetics of AM,and the reaction rate constant and activation energy obtained by calculation were similar to the experimental value,which built the calculation model for the system dynamics and laid the foundation for the further analysis of the polymerization mechanism.