| CPC E21B 15/003 (2013.01) [E21B 7/023 (2013.01); E21B 15/006 (2013.01); E21B 19/14 (2013.01)] | 14 Claims |

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1. A land-based drilling rig comprising:
a drill rig floor, the drill rig floor having a V-door, the V-door defining a V-door side of the drill rig floor;
a subfloor, the subfloor supporting the drill rig floor, wherein the drill rig floor is movable relative to the subfloor and thereby is adapted to traverse atop the subfloor;
a plurality of substructure boxes, the substructure boxes supporting the subfloor, each substructure box including a lower substructure box and two upper substructure boxes, wherein there is a gap between the two upper substructure boxes and wherein the lower substructure box is a rectangular prism with the long side parallel to the V-door side of the drill rig floor that extends the length of the subfloor; and
a mast, the mast mechanically coupled to the drill rig floor, the mast having an open side and having a V-door side where the V-door side of the mast faces the V-door side of the drill rig floor.
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