Synthesis And Application Of Nano-micron Polymer Microspheres For Low-permeable Oil Reservoir

Nano-micron polymer microspheres,a novel kind of functional material applying to deep profile control for oil displacement made from polyacrylamide and its derivatives,has been used effectively to enhance oil recovery.Due to the large amounts of hydrophilic functional group,the polymer microsphere can expand and gel to plug the pore throats of underground.Because of the poor physical properties of reservoirs and the small size of pore throats,it is difficult to meet the actual needs by using microspheres with single size.Therefore,the development of nano-micron polymer microspheres with a series of particle size distributions is of great importance.In this paper,nano-micron polyacrylamide copolymer microspheres were prepared by inverse emulsion polymerization.The influences of the emulsifier(HLB value,dosage),initiator(type and dosage),monomer concentration,reaction temperature and stirring speed on the stability of the emulsion system were discussed.The particle size of the microspheres can be effectively controlled via changing the stirring speed and the amount of emulsifier.The microspheres were characterized by Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM),optical microscope,laser particle size analyzer and thermogravimetric analyzer(TGA).The composition,morphology,thermal stability and swelling property of the microspheres were also observed and analyzed.The results indicated that the microspheres with initial particle diameters of 0.3-3 ?m had high degree of sphericity and good thermal stability.The microscopic process of microspheres swelling under the condition of mineralized water at 60 °C was observed.The size of the expanded microspheres ranges from several to tens microns,which can meet the practical application requirements.The plugging performance of the polymer microspheres with different initial particle sizes was evaluated by the simulation experiment of the sand filling tube model in the room.The field experiments were carried out on the basis of indoor experiment.The results showed that,the microspheres with initial particle diameters of 0.3-3 ?m possessed the ability of blocking,and the blocking rate of the microspheres with initial particle size of 0.3 ?m was 89.2%.Microspheres with different particle size also exhibited the effect of increasing oil and reducing water in field experiment.The polymer microspheres have the ability to block the low-permeable oil reservoir.