The invention discloses a modified
epoxy asphalt particle, a water-in-oil base
drilling fluid and a preparation method thereof. The modified
epoxy asphalt particles include a core made of
epoxy asphalt and a shell formed by a modifier. In parts by
mass, the core is 7-9 parts, and the shell is 1-3 parts; the modifier includes Polymerized
sulfur and free
sulfur, the weight ratio of polymerized
sulfur and free sulfur in the modifier is 3:7~7:3. The water-in-oil-based
drilling fluid, in terms of
mass fraction, includes 0.5% to 5% of the main emulsifier, 0.1% to 3% of the auxiliary emulsifier, 1% to 3% of organic soil, and 1% to 5% of modified epoxy asphalt particles. %, the balance is oil-water base. The water-in-
oil drilling fluid of the present invention uses modified epoxy asphalt particles as a performance
regulator, which can maintain a good particle state and high-temperature deformation ability in the water-in-
oil drilling fluid, and improves plugging and fluid loss reduction Effect.