Preparation And Properties Of Magnetic Composite Particles

With the increasing demand for energy, shale gas exploration and development is paid more and more attention. In the process of shale gas drilling, a large number of mud shale formation need to drill. Because shale formation is easy to absorb water and has a small pore throat size, it is difficult to block. Therefore, it needs to use nanoparticles to modify the drilling fluid. It will improve the comprehensive performance of drilling fluid and provide bases for shale gas exploration and development.Magnetic nanoparticles not only has the special performance of magnetic materials, but also has the special effect of nanoparticles. In this paper, we prepared the magnetic nanoparticles, and investigated the heat resistance and salt resistance of the magnetic nanoparticles. Also we studied the compatibility of the magnetic nanoparticles with the drilling fluid additives.We prepared the magnetic nanoparticles by simple coprecipitation method, and used polymers to modify the surface of the prepared nanoparticles. After modified, we inspected the structures and properties of the magnetic composite particles. The research contents are as follows:1. We prepared the polyacrylic acid (PAA), acrylic acid/acrylamide binary copolymer P(AA-co-AM) and poly (sodium styrene sulfonate) (PNaSS) by solution polymerization. The three kinds of polymers respectively contained -COOH,-COOH and-NH2, SO3-,As-COOH and SO3- could be grafted onto the surface of the magnetic nanoparticles by hydrogen-bond interaction with-OH, the three kinds of polymers could be used in the surface modification of the magnetic particles.2. The results of XRD、TEM and FT-IR tests indicated that the three kinds of polymers were successfully grafted onto the surface of magnetic nanoparticles and thought that the Fe3O4-PAA、Fe3O4-P(AA-co-AM)、Fe3O4-PNaSS magnetic composite particles had synthesized. At the same time, the results of TG and DSC analysis showed that the three kinds of magnetic composite particles had good thermal stability and the three kinds of magnetic composite particles coated quantity, in turn, was about 16.33wt%,15.79wt%, and 9.28wt%. In addition, in the investigation of the magnetic response performance of the three kinds of magnetic composite particles, we found that the magnetic response performance of the three magnetic composite particles are not affected by dispersion in water. All of the three kinds of magnetic composite particles could be separated and dispersed in water rapidly.3. In the investigation of the heat resistance and salt resistance of the three kinds of magnetic composite particles aqueous dispersion, we found that the suspension stability time of Fe3O4-PAA composite particles aqueous dispersion was 15 days at 0.1% of salt concentration; and the suspension stability time of Fe3O4-P(AA-co-AM) was 12 days at 0.1% of salt concentration; and the suspension stability time of Fe3O4-PNaSS was 28 days at 0.5% of salt concentration. We found that the Fe3O4-PAA had a well temperature resistance property at the range from 80 to 160℃; and the Fe3O4-P(AA-co-AM) had a well temperature resistance property at the range from 80 to 210℃;and the Fe3O4-PNaSS had a well temperature resisitance property at the range from 80 to 210℃. Also we found that during 80 to 180℃, the Fe3O4-PAA had a well temperature and salt resistance performance at 0.1% to 2% of salt concentration; during 110 to 200℃, the Fe3O4-P(AA-co-AM) had a well temperature and salt resistance performance at 0.1% to 1% of salt concentration; during 80 to 200℃, the Fe3O4-PNaSS had a well temperature and salt resistance performance at 0.1% to 2% of salt concentration in the same way. So all the three kinds of magnetic composite particles had well temperature resistance at certain salt concentration.4. In the investigation of the compatibility of the three kinds of magnetic composite particles aqueous dispersion, we found that during 150 to 180℃, the Fe3O4-PAA had a well compatibility stability with sodium carboxymethye cellulose(CMC) at 1%、2% and 3% of CMC concentration; during 80 to 160℃, the Fe3O4-P(AA-co-AM) had a well compatibility stability with CMC at 1% of CMC concentration; during 80 to 170℃, the Fe3O4-PNaSS had a well compatibility stability with CMC at 1% and 2% of CMC concentration. Also we found that during 80 to 190℃, the Fe3O4-PAA had a well compatibility stability with sulfonated-pheno-formoldehyde resin(SMP) at 1%、2% and 3% of SMP concentration; during 80 to 200℃, the Fe3O4-P(AA-co-AM) had a well compatibility stability with SMP at 1%,2% and 3% of SMP concentration; during 80 to 190℃, the Fe3O4-PNaSS had a well compatibility stability with SMP at 1%,2% and 3% of SMP concentration in the same way.