Some really big 2000 HP onshore rigs with 38 foot substructures and most offshore jack-ups, even floaters (semi-submersibles) used in shallow water, often have a "sub-floor" immediately under the rig floor, below the rotary table. This sub-floor can be set below the rotating head, bell-nipple and Hydril or below the first set of blind rams; it can appear to be little more than a platform or a deck. The height of these floor(s) can be adjusted as they are often hung from the overlying substructure with cables. Some of them can be quite large and are often fixed permanently to the substructure. They are called Texas decks, or a Texas floor. Most often the Texas floor can be accessed from the rig floor or from outside the substructure. They allow hands to work on the BOP stack. The term Texas floor, or Texas deck is used all over the world.
You can now add this new term to the long list of other very important drilling rig terms, like possum bellies, grasshoppers, V-doors, bird baths, moon pools, mouse holes and dog houses. This stuff is important oilfield lingo that folks should know.
Texas floor on a big jackup rig being hoisted in place
Photo by David Thompson, Senior Well Control Specialist for Boots and Coots, Inc.
I am not sure you would call this a Texas "floor" but you probably would not want to be dancing on it right now, whatever it is. This is a blowout for Lagoven in Lake Maracaibo in Venezuela in 1993. The spool below the fill up lines has cut out badly at the flange to flange connection and surface control has been lost, the barge rig abandoned. Thats a mouse hole shuck in the foreground hanging from the rig floor and the step ladder wedged up against some railing was used to access bleed off lines and the hydraulic lines to the pipe and blind rams.
On deck...nasty oil-base mud