Shale drilling auxiliary corrosion inhibitor and preparation and use method thereof and mixed corrosion inhibitor

The invention provides a shale drilling auxiliary corrosion inhibitor and a preparation method and a use method thereof, and a mixed corrosion inhibitor. The preparation method comprises the followingsteps: uniformly mixing first powder, second powder and third powder to prepare the shale drilling auxiliary corrosion inhibitor. The first powder is prepared by the following steps: uniformly mixing20-25 parts by weight of epoxy succinic acid amine, 9-20 parts by weight of magnesium hydroxybutylidene phosphate and 12-15 parts by weight of ethylenetriamine pentaacetic acid amine, and performinggrinding, crushing, sieving and stirring to obtain the first powder; the second powder is prepared by uniformly mixing and sieving 8-12 parts of active attapulgite, 8-12 parts of ammonium persulfate and 12-17 parts of sulfonated succinate; and the third powder is prepared by uniformly mixing 7-13 parts of butyl propionate, 8-14 parts of sodium dodecyl benzene sulfonate and 3-9 parts of an organiccomplexing agent and sieving