Rig Footing – Stability Considerations
Adequate Foundations are an essential element in providing Stability for Masts, Rig carriers, and substructures. Foundation design should consider safe bearing loads at mast, substructure, and rig carrier support points.
The area around the main support jacks shall be graded, leveled, and maintained so that oil, water, and drilling fluids will drain away from the work area.
Supplemental footing such as rig mats made out of timber or steel shall be used to distribute the concentrated loads from the mast to rig support points.
The rig manufacturer load distribution diagram will indicate these locations.
Wellhead cellars at a well location may present special considerations for safe operations of a portable mast.
Earthen cellars have the potential for cave in. They also fill with rain water, wellbore fluids, and other fluids that can seep into the ground under the mast supplemental footing and reduce safe bearing capacity of the soil. Cellars lined with timbers have the same seepage potential. Large concrete cellars may require a qualified person to inspect the integrity and large steel beams to span the cellar in order to provide the suitable mast support.