| In this paper,we prepared the magnetic nanoparticles,polymer modified magnetic nanoparticles were prepared by free radical polymerization,and investigated the heat resistance and salt resistance of the magnetic nanoparticles by rheological and fliud loss tests.Also we studied the compatibility of the magnetic nanoparticles with the drilling fluid additives.1.Poly(acrylic acid)(PAA)was grafted with Fe3O4 nanoparticles modified with 3-(methacryloyloxy)propyltrimethoxysilane(TMSPMA)followed by drilling fluid containing 4 wt%bentonite.Rheological tests show that with the increase of the composite nanoparticle concentration,the shear dilution performance of drilling fluid is not stable.The consistency index(K)of Fe3O4/PAAAVBDFs was observed to decrease at higher concentrations of Fe3O4/PAA.As the temperature increases,the amount of fluid loss also gradually increases.The effects of temperature and concentration of composite nanoparticles on the filtration loss were experimentally studied.The HTHP test is conducted at different temperature and concentration gradients.The results show that when the concentration of composite nanoparticles reaches 0.1 wt%,the filtration performance of water-based drilling fluid is the best.In the salt tolerance test,the dispersion stability of Fe3O4/PAA nanoparticles decreased with the same salt concentration.The higher the concentration of composite nanoparticles is,the less the filtration loss become.However,when the concentration of nanoparticles was 0.1 wt%,the filtration loss reached minum.Compared with the base slurry,Fe3O4/PAA nanoparticle solution has a higher temperature resistance,under the conditions of high temperature and pressure,has a wide range of applications.2.Poly(sodium p-styrene sulfonate)(PSSS)was grafted with Fe3O4 nanoparticles modified with 3-(methacryloyloxy)propyltrimethoxysilane(TMSPMA)and then introduced into WBDFs containing 4 wt%BT.The effect of temperature on fluid loss and rheological properties of drilling fluid was studied.Rheological tests showed that the shear-thinning properties of WBDFs at different concentrations of Fe3O4/PSSS nanoparticle at 0.1 wt%were perfect at different temperatures.The rheological curve is Bingham model at low temperatures,but Herschel-Bulkley model is more fit at high temperature.In rheological tests,the results show that increasing the concentration of Fe3O4/PSSS nanoparticles can effectively improve salt tolerance.In the high temperature and high pressure(HTHP)filtration test,the results show that the filtration loss of Fe3O4/PSSS nanoparticles is as low as 0.1 wt%.In the salt tolerance test,increasing the concentration of Fe3O4/PSSS nanoparticles can effectively reduce the fluid loss.Depending on the salt content in different formations,the concentration of Fe3O4/PSSS nanoparticles can be controlled flexibly to show its potential in high temperature wells.3.Poly-2-acrylamide-2-methylpropanesulfonic acid(PAMPS)was grafted with Fe3O4 nanoparticles modified with 3-(methacryloyloxy)propyltrimethoxysilane(TMSPMA)and then introduced into WBDFs containing 4 wt%BT.The effect of temperature on fluid loss and rheological properties was investigated.Rheological tests showed that the shear thinning performance of drilling fluid was the best at different temperatures when the concentration of Fe3O4/PAMPS nanoparticles reached 0.1 wt%.The rheological curve corresponds to the Bingham model at lower temperatures,but the curve corresponds to the Herschel-Bulkley model at higher temperatures.In the rheology and salt tolerance test,it was found that increasing the concentration of Fe3O4/PAMPS nanoparticles can effectively improve salt tolerance.In the study of HTHP filtration loss,it was found that the drilling fluid exhibited the lowest fluid loss at different temperatures when the Fe3O4/PAMPS nanoparticle concentration reached 0.1 wt%.In the salt tolerance test,the higher the concentration of Fe3O4/PAMPS nanoparticles is,the less the filtrate loss at the same salt concentration.When the nanoparticle concentration reached 0.2 wt%,WBDFs had the best filtration loss under different salt concentrations.4.Poly(sodium p-styrene sulfonate)(PDMC)was grafted with Fe3O4 nanoparticles modified with 3-(methacryloyloxy)propyltrimethoxysilane(TMSPMA)and then introduced into WBDFs containing 4 wt%BT.The effect of temperature on fluid loss and rheological properties of drilling fluid was studied.By introducing Fe3O4/PDMC nanoparticles,rheology and filtrate performance of water-based drilling fluids are improved.When the concentration of Fe3O4/PDMC nanoparticles reaches 0.1 wt%,the water-based drilling fluid has excellent fluid loss.However,when the concentration of Fe3O4/PDMC nanoparticles reaches 0.2 wt%,the water-based drilling fluid has excellent filtration loss under different concentrations of KCl.Nanoparticles can seal the nanopores or micropores in the filter cake,and the filtration loss is obviously reduced,indicating that it is an effective fluid loss reducer.In the rheological model,Bingham and Herschel-Bulkley models perform the best in predicting the rheological properties of Fe3O4/PDMC modified water-based drilling fluids.The unique nature of the composite particles makes it ideal for next-generation fluid loss control and rheological modification of water-based drilling fluids.When KCl concentration reached 0.5 wt%,the Fe3O4/PDMC modified water-based drilling fluid reached a transitional concentration of plastic fluid to pseudoplastic fluid.5.Poly(sodium p-styrene sulfonate)(PAM)was grafted with Fe3O4 nanoparticles modified with 3-(methacryloyloxy)propyltrimethoxysilane(TMSPMA)and then introduced into WBDFs containing 4 wt%BT.The effect of temperature on fluid loss and rheological properties of drilling fluid was studied.Rheological tests showed that the shear-thinning properties of WBDFs were excellent at different temperatures when the concentration of Fe3O4/PAM nanoparticles reached 0.1 wt%.In rheological tests,the results show that increasing the concentration of Fe3O4/PAM nanoparticles can effectively improve salt tolerance.In the high temperature and high pressure(HTHP)filtrate loss test,the results show that when the concentration of Fe3O4/PAM nanoparticles is as low as 0.1 wt%,the filtrate loss is the smallest.Salt tolerance test,increasing the concentration of Fe3O4/PAM nanoparticles can effectively reduce the amount of fluid loss.Depending on the salt content in different formations,the concentration of Fe3O4/PAM nanoparticles can be controlled flexibly to show its potential in high temperature wells.6.Poly(N-isopropylacrylamide)(PNIPAM)was grafted with Fe3O4 nanoparticles modified with 3-(methacryloyloxy)propyltrimethoxysilane(TMSPMA)and then introduced into water-based fluid containing 4 wt%BT.The effect of temperature on fluid loss and rheological properties of drilling fluid was studied.Through the introduction of Fe3O4/PNIPAM nanoparticles,rheology and filtrate performance of water-based drilling fluids are improved.When the concentration of Fe3O4/PNIPAM nanoparticles reaches 0.1-0.25 wt%,water-based drilling fluids have superior fluid loss,less fluid loss and thinner filter cake than other concentrations of particles.However,when the concentration of Fe3O4/PNIPAM nanoparticles reaches 0.25 wt%,the water-based drilling fluid has excellent filtration loss under different concentrations of KCl.Nanoparticles can seal the nanopores or micropores in the filter cake,and the filtration loss is obviously reduced,indicating that it is an effective fluid loss reducer.The rheological properties of Fe3O4/PNIPAM modified water-based drilling fluids were found to fit with the Bingham model and the Herschel-Bulkely model.When the concentration of Fe3O4/PNIPAM nanoparticle reaches 0.25 wt%,the transitional concentration of Fe3O4/PNIPAM modified water-based drilling fluid to transition from plastic fluid to pseudoplastic fluid is achieved.Depending on the salt content in different formations,the concentration of Fe3O4/PNIPAM nanoparticles can be controlled flexibly to show its potential in high temperature wells. |
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