Alpha-olefin base fluid and application thereof in drilling fluid

The invention relates to alpha-olefin base fluid and application thereof in drilling fluid. The alpha-olefin base fluid comprises linear alpha-olefin, a nonionic surfactant, mineral oil and liquid paraffin. The mass ratio of the linear alpha-olefin to the nonionic surfactant to the mineral oil to the liquid paraffin is (90-100): (4-5): (8-10): (1-2). The alpha-olefin base fluid can effectively avoid the adverse consequences of pump pressure rise, stratum fracture, borehole wall instability and the like caused by viscosity rise of drilling fluid due to too low temperature in the drilling process. Meanwhile, the alpha-olefin drilling fluid provided by the invention also comprises perlite with a specific expansion multiple, the perlite is used as a weighting substance of the alpha-olefin drilling fluid at low temperature, and the perlite is softened when the temperature rises, so that the drilling fluid can keep stable viscosity at high temperature, and the drilling fluid has good stability. Therefore, the alpha