The invention discloses a preparation method of a
polyamide inhibitor for
drilling fluid. The preparation method comprises the following steps: (a) dissolving a substance A in an
alcohol solvent, andadding a substance B into the
alcohol solution of the substance A, wherein the
mass ratio of A to B is (1 to 1.5): 1, the
reaction temperature is 45-70 DEG C, and the reaction time is 12-24h, so as toobtain an
intermediate product; (b) adding a substance C and a catalyst into the
intermediate product, wherein the
mass ratio of C to A is (0.5 to 1.2): 1, and the dosage of the catalyst accounts for1% of the substance A; heating to a
reflux temperature, and reacting for 4-12h at the
reflux temperature; (c) distiling out the
solvent alcohol to obtain a product. The
polyamide inhibitor prepared by the invention has the characteristics of remarkable high-temperature resisting and inhibiting effect, and little
impact on rheological property and the like, and is suitable for different water-based
drilling fluid systems. The
polyamide inhibitor can prevent the problem of borehole
instability caused by hydration dispersion and expansion of
clay minerals on water-sensitive formation, and also can effectively stabilize the rheological property of the
drilling fluid system so as to avoid failure in
performance control.