Marine-drilling sub-base assembly for a soft-bottom foundation

摘要

A drilling sub-base assembly for use from an offshore drilling vessel wherein drilling operations are conducted through a moon pool and at a drilling site where the bottom soil conditions are soft or unstable such that a conventional drilling sub-base dimensioned to pass through the moon pool would not provide an adequate foundational base for the carrying-on of drilling operations. The drilling sub-base assembly includes a main section dimensioned for ease of passage through the moon pool of the vessel and secondary sections pivotally affixed to the main section on at least two opposite sides thereof to be in a substantially vertical position relative to the main section when the drilling sub-base assembly is located in the moon pool and to be in a substantially horizontal position relative to the main section when the drilling sub- base assembly is positioned on the underwater bottom. With the secondary sections extended into their horizontal position and restrained from moving to a position above the horizontal, the drilling sub-base assembly provides the necessary cross-sectional bearing area to support drilling operations conducted into the soft underwater bottom. With the secondary sections in their vertical position, the drilling sub-base assembly may pass through the moon pool.