Horizontal well segmented substitution well killing method and device

The invention discloses a horizontal well segmented substitution well killing method and device. The horizontal well segmented substitution well killing method comprises the particular steps that whena horizontal well is drilled to a horizontal segment and gas invasion occurs, well shut-in treatment is carried out, and the pressure condition of a casing is monitored; when the pressure of the casing achieves a preset threshold value, the current well shut-in casing pressure and the well shut-in stand pressure are obtained; the well shut-in casing pressure and the well shut-in stand pressure are used as a standard, the changing condition of the casing in a preset period is monitored, and when the casing pressure is on the rise, gas in a vertical well segment of the horizontal well is subjected to substitution discharging by a volumetric approach; when the casing pressure in the preset period does not rise, well killing fluid is injected into the horizontal segment of the horizontal wellthrough a drilling string