Patent attributes
A collapsible drilling rig substructure is transported to a drilling site while in a collapsed transportation configuration wherein a raisable floor of the substructure is in a lowered transportation position relative to a fixed drill floor such that an upper surface of the raisable floor is positioned at a first height level above a base of the substructure while an upper surface of the fixed drill floor is positioned at a second height level above the base that is greater than the first height level. The substructure is positioned adjacent to a wellbore location at the drilling site and reconfigured from the lowered transportation configuration to a raised operating configuration by raising the raisable floor to an operating position laterally adjacent to the fixed drill floor while maintaining a height level of the upper surface of the fixed drill floor at the second height level.
