The invention relates to an ultrahigh-temperature-resistant and complex-salt-resistant amphoteric
ion hydrophobic association
polymer filter loss
reducer and a preparation method thereof. The filter loss
reducer is a multipolymer with amphoteric
ion hydrophobic association characteristic and is generated by performing
polymerization reaction on hydrophobic alkylamide, strong hydrophilic anion alkenyl
sulfonate and strong hydrophilic cationic alkenyl
quaternary ammonium through a water-soluble azo initiator in an
aqueous solution, wherein the generated multipolymer molecular chain contains about 2,000 to 4,000 structural units, and the weight-average molecular
weight range is 1,320,000 to 2,100,000. The multipolymer filter loss
reducer has high compatibility in an ultrahigh-temperature water-based
drilling fluid well completion fluid, can obviously reduce the filter loss quantity of the
drilling fluid well completion fluid under the ultrahigh-temperature environment, has
temperature resistance capable of reaching 248 DEG C, saturated
sodium chloride resistance and excellent complex
salt resistance, and can obviously reduce the filter loss quantity in the water-based high-temperaturedrilling fluid with the chloridion concentration higher than 100,000 ppm,
calcium ion concentration higher than 5,000 ppm and
magnesium ion concentration higher than 5,000 pmm and invaded with acidicgas.