The invention discloses a cationic
polyamine polymer, and a preparation method and application thereof. The cationic
polyamine polymer contains double main chains, and can form a grid structure. The preparation method uses terminal
diamine,
cyclic ether and
epoxy chloropropane as
raw material, and comprises the following steps: while stirring, dropwisely adding
cyclic ether into terminal
diamine at 60-100 DEG C to react for 1-4 hours to generate a compound of which the
structural formula is (II), wherein the mol ratio of the terminal
diamine to the dropwisely added
cyclic ether is 1:2; heating to 90-150 DEG C, and dropwisely adding
epoxy chloropropane while stirring, wherein the mol ratio of the dropwisely added
epoxy chloropropane to the terminal diamine is 2:1; after the
reaction system becomes thicker, keeping the state for at least half an hour, adding a terminator, and continuing the reaction for 1-4 hours to obtain a cationic
polyamine polymer sample, wherein the mol ratio of the terminator to the terminal diamine is 2:1. The cationic polyamine polymer can be used as a
drilling fluid shale inhibitor. The cationic polyamine polymer contains abundant hydroxy groups, and has favorable water
solubility; the cationic polyamine polymer can effectively inhibit the hydration expansion and dispersion of clay; and the cationic polyamine polymer provides certain lubricating property, and is environment-friendly.