Abstract: A synergist for a water-base drilling fluid and a preparation method therefor, a water-base drilling fluid and an application thereof, and belongs to the field of drilling fluid technologies. The synergist is prepared from raw materials comprising the following parts by weight: 15˜25 parts of sodium styrene sulfonate, 8˜15 parts of allyl trimethyl ammonium chloride, 2˜8 parts of didodecyldimethylammonium bromide, 1˜5 parts of n-octyl triethoxysilane, 1˜5 parts of propyltriethoxysilane, 1˜5 parts of disodium lauryl sulfosuccinate, 10˜20 parts of nano silica, 8˜15 parts of paraffin, and the like.

Abstract: The present disclosure relates to the technical field of water-based drilling fluid, in particular to a modified polyhistidine suitable for being used as a supramolecular shale inhibitor, a method of preparing the same, and its application in water-based drilling fluids. The modified polyhistidine has a histidine polymerization main chain comprising a structural unit, which is represented by Formula (1) and attached with a modifying group, and the histidine polymerization main chain has a histidine polymerization degree of 6-9. The modified polyhistidine provided by the present disclosure is a degradable biological material and has the advantage of environmental friendliness; when the modified polyhistidine is used as a shale inhibitor, it can take advantage of its supermolecular property to effectively inhibit the hydration expansion of montmorillonite which is the most important expansion mineral in shale, and exhibits excellent inhibition effect and desirable temperature resistance.