The Preparation And Performance Study Of Polyacrylamide Gel Microspheres

This topic focused on the field of oil exploration, particularly involved in oil field deep flooding of strong heterogeneity, high water content and the development of large pore. Water drive reservoir has many problems, such as high water cut, water channeling and invalid circulation of water injection; other traditional flooding technologies were restricted by reservoir and geological conditions. The polymer gel microspheres were a new profile control and flooding agent and it could deform and migrate to the deep formation under the external force, change the flow of injected water, improve the swept area and improve the effect of water flooding and enhance oil recovery in the oilfield.In this paper, inverse emulsion polymerization and dispersion polymerization were applied to prepare different particle size range of polyacrylamide hydrogel microspheres for oilfield flooding agent. First, Polyacrylamide hydrogel microspheres in the size range of 500nm-5?m and 5 ?m-15?m were prepared by inverse emulsion polymerization and dispersion polymerization, respectively and the experimental conditions were optimized. The impact of the emulsifier type and amount on the polymerization process stability was mainly discussed, the polymerization temperature, stirring speed, the amount of cross-linker agent and initiator, monomer ratios produce an effect on particle size were also studied. Infrared transform infrared spectroscopy and thermal gravimetric analysis were used to characterize the chemical composition and thermal stability of the microspheres; using scanning electron microscopy, polarized light microscope to observe the morphology of the microspheres; laser particle size analyzer was used to analyze the particle size distribution of the microspheres. The different salinity had an effect on the swelling property of microspheres. The heat resistance and salt tolerance performance of the microspheres was investigated.Polyacrylamide microspheres prepared by emulsion polymerization method, the selection and dosage of emulsifier is important for the stability of the emulsion and reaction process. The following factors had great influence to the particle size and its distribution of microspheres:stirring faster and more initiator resulted in the smaller particle size; by changing the initiator addition method, we could get more uniform particle size distribution of microspheres. A higher monomer conversion rate was obtained by controlling the reaction temperature and reaction time; the amount of cross-linker agent had no significant effect on microsphere size.The swelling performance of microspheres was an important parameter affecting the migration and plugging ability of microspheres. In order to satisfy different depth of strata sealing need, the crosslinking degree of microspheres could be controlled to receive an in a wide range of swelling ratio. Under the condition of 70?, microspheres contained different crosslinking degree swelling 7 days, the swelling ratio could be from 20 to 50 times in water; 8-25 times in mineralized water which contained different concentration of calcium and magnesium ions and 10-20 times in mineralized water which contained different concentration of sodium ions. Improve the swelling temperature also could help. Therefore, two kinds of microspheres had heat resistance and salt tolerance.The sand-filled pipe simulation plugging experimental was carried at 60?, the microspheres with different size were respectively dispersed in oilfield formation water under 0.1 wt%. For the microspheres with average diameter of 5 ?m and 12 ?m, plugging ratio closured 80% and 90% after swelling 5 days, respectively. These values could meet the requirements for most of oilfield.By comparing the plugging performance of the microspheres prepared by different polymerization methods, potential applied geological conditions of different size range of polymer microspheres were put forward.