Oil soluble cationic broad-spectrum temporary blocking agent in use for drilling fluid

This invention relates to an oil-soluble cationic broad-spectrum temporary blocking agent for well drilling fluid. The oil-soluble cationic broad-spectrum temporary blocking agent comprises: oil-soluble materials 50-74%, SBS triblock copolymer 0.2-0.44%, epoxypropylbenzyl di(stearamide ethyl) ammonium salt 0.50-0.89%, cationic surfactant imidazoline 0.62-0.96%, dibenzyl-di(stearamide ethyl) ammonium salt 0.62-0.96%, carboxymethyl cellulose or hydroxyethyl cellulose 0.17-0.84$, CaCl2 0.2-0.25%, and water as balance. The oil-soluble materials include residue asphalt (softening point = 51-55 deg.C), semi-oxidized asphalt (softening point = 57-65 deg.C), ethylene pyrolysis coal tar pitch (softening point = 47-52 deg.C), propane-removed asphalt (softening point = 70-77 deg.C), extracted asphalt (softening point = 105-120 deg.C), and 100# heavy oil asphalt (softening point = 47-54 deg.C) at a weight ratio of 1:(1.88-2.5):(1.25-1.88):(3.12-3.75):(2.5-3.12):(1.5-2). The oil-soluble cationic broad-spectrum temporary blocking agent has such advantages as high oil solubility, high softening degree, wide softening point range, strong positive electricity, high lubricity, good fluid-loss inhibitive effect, high recovery rate of core permeability, low temporary blocking depth, high strength, good de-blocking effect, no pollution, low labor intensity, little influence on well drilling fluid construction performance, and simple process.