Multi-branch horizontal well structure and grouting water damage prevention method

The invention discloses a multi-branch horizontal well structure. A drilled hole of the multi-branch horizontal well structure comprises a vertical hole section, a deflecting section and a horizontal section. The horizontal section is located in a to-be-blocked limestone layer area and comprises a main hole, a plurality of branch holes are symmetrically connected to the two sides of the main hole, and lockrand holes are formed in the two sides of the main hole, extend along the edge of a blocked target area and surround the main hole and the branch holes; the grouting pressure of the main hole and the branch hole predetermined by the worker is P, and the grouting pressure corresponding to the lockrand hole is 0.1-0.3 P. The invention further discloses a corresponding grouting water damage prevention method. The edge of the plugging target area is subjected to grouting plugging through lockrand hole grouting, so that the grouting blind area can be reduced or even eliminated, the situation that a large amount o