Substructures (drilling rig) Information
Substructures are the structural components of land and water-based oil platforms which support the derrick, mast, or other rig components, as well as providing storage space below the main deck. They are customized according to an application's needs, but there are several classifications for substructures.
Box-on-box and skin and trailer-type substructures a self-standing structures with a relatively-high front platform for the installation of a blowout preventer, and low back platform to accommodate drilling equipment, transmission units, or other heavy machinery.
Slingshot substructures are self-elevating. The drill floor and platform allow a cantilevered mast to be installed at ground floor. The mast and substructure raise into working position and hydraulic cylinders at the sides of the mast act as bumpers. This substructure is acceptable for electrical rigs.
Telescoping substructures are lightweight and easily install and relocate. Hydraulics lift the mast into position.
Spin-up substructures place the mast at ground level, and the substructure and mast raise into position together for operation via the use of screws.
Swing-lift substructures are placed on arms which have joints placed on the ground and the underside of the platform. Hydraulic pistons raise the platform which has a cut-out to accommodate the ground-fixed mast.
The most notable standard concerning drilling substructures is the American Petroleum Institute's standard SPEC4F. It includes recommendations for steel substructures, as well as drilling and well-servicing operations. A rating method is also enclosed.