Synthesis And Association Behavior Of Hydrophobically Associating Polymer Microsphere

Crosslinked polyacrylamide microspheres,as an important modifying and flooding agent,are widely used in deep-profile control technology due to their unique particle size controllability,good swellability,salt tolerance,excellent elasticity and injectability.Hydrophobically associating polymers have different solution properties from general polymers due to their unique associations.Swelling microspheres can enhance their plugging effect if they can produce hydrophobic association in the formation.In this thesis,three series of hydrophobically associating polymer microspheres were synthesized using low temperature reverse suspension polymerization by adding three different hydrophobic monomers(numbered S,X,J)with acrylamide.The basic properties of the microspheres were characterized by optical microscopy,scanning electron microscopy and infrared spectroscopy(FT-IR).The association behavior and rheological property of the microspheres were studied by laser particle size analyzer,HAKKE rheometer and fluorescence spectroscopy.The results show that the particle size distribution of three series of microspheres is all in the range of 1?50?m.When the association behavior is the most obvious,the amount of hydrophobic monomer added is 1%.The CAC of S series,X series and J series microspheres is 5000mg/L,10000mg/L and 10000mg/L,respectively.The microspheres have good dispersibility with mass concentration before CAC,there is a single peak in microsphere particle size distribution.The steady state shear curve consists of two stages:pseudoplastic fluid stage and non-Newtonian fluid stage.When the mass concentration reaches CAC,the microspheres are in a state of aggregation,which lead to the right shift of two peaks in the particle size distribution,and its steady state shear curve consists of three stages:pseudoplastic fluid stage,non-Newtonian fluid stage and dilatant fluid stage.The average particle size and apparent viscosity of the microsphere solution decrease slightly with the increase of NaCl mass concentration,then increase slightly.For CaCl₂,the average particle size and apparent viscosity of the microsphere solution decrease with the increase of CaCl₂ mass concentration,then decrease and finally increase.The influence of Ca²⁺to association behavior is greater than that of Na⁺.Compared with polyacrylamide microspheres,hydrophobically associating polyacrylamide microspheres have better salt resistance.