Plugging agent, oil-based drilling fluid, preparation method of oil-based drilling fluid and well drilling method

The embodiment of the invention provides a plugging agent, an oil-based drilling fluid, a preparation method and a drilling method, and belongs to the field of drilling. The plugging agent comprises the following components in mass ratio: water, asphalt, a first emulsifier, rubber micro powder and barite powder, wherein the mass ratio of the water to the asphalt to the first emulsifier to the rubber micro powder to the barite powder is 100: (10-37): (2-4): (10-45): (3-15). According to the plugging agent provided by the embodiment of the invention, the rubber micro powder and the asphalt are used for providing deformable flexible particles, the barite powder is used for providing rigid particles, and the rigid particles can be used for forming a stable bridge; the flexible particles can deform under the conditions of high temperature and high pressure, and a plurality of components have a synergistic effect, so that the plugging agent provided by the embodiment of the invention has a better plugging effect. 本