Patent ID: 9091125
Filing Date: 2015-07-28
Classification: E21B

Abstract:
1. A drilling rig substructure, comprising: a base; a fixed drill floor mounted on said base, wherein an upper surface of said fixed drill floor is adapted to be positioned at an operating height level that is a same first distance above said base during both transportation of said drilling rig substructure to a drilling site and while performing drilling operations at a wellbore location of said drilling site; and a raisable floor that is adapted to be positioned in a lowered transportation position during said transportation of said drilling rig substructure to said drilling site and raised from said lowered transportation position to an operating position adjacent to said fixed drill floor for performing said drilling operations, wherein an upper surface of said raisable floor is adapted to be positioned at a transportation height level that is a second distance above said base when said raisable floor is positioned in said lowered transportation position, said second distance being less than said first distance, and wherein a plane defined by said upper surface of said raisable floor is adapted to be substantially parallel to a plane defined by said upper surface of said fixed drill floor when said raisable floor is in said lowered transportation position during said transportation of said drilling rig substructure to said drilling site and when said raisable floor is in said raised operating position during said drilling operations.