Polyacrylamide microspheres have been successfully
used to reduce water production in reservoirs, but
it is impossible to distinguish polyacrylamide microspheres
from polyacrylamide that is used to enhance oil recovery
and is already present in production fluids. In order to
detect polyacrylamide microspheres in the reservoir produced
fluid, fluorescent polyacrylamide microspheres
P(AM-BA-AMCO), which fluoresce under ultraviolet
irradiation, were synthesized via an inverse suspension
polymerization. In order to keep the particle size distribution
in a narrow range, the synthesis conditions of the
polymerization were studied, including the stirring speed
and the concentrations of initiator, Na2CO3, and dispersant.
The bonding characteristics of microspheres were determined
by Fourier transform infrared spectroscopy. The
surface morphology of these microspheres was observed
under ultraviolet irradiation with an inverse fluorescence
microscope. A laboratory evaluation test showed that the
fluorescent polymer microspheres had good water swelling
capability, thus they had the ability to plug and migrate in a
sand pack. The plugging rate was 99.8 % and the residual
resistance coefficient was 800 after microsphere treatment
in the sand pack. Furthermore, the fluorescent microspheres
and their fragments were accurately detected under ultraviolet
irradiation in the produced fluid, even though they
had experienced extrusion and deformation in the sand
pack.