Subsea wellhead spud-in marking and as-built position estimation method based on ultra-short baseline acoustic positioning
Arkadiusz Tomczak, G. Stępień, Tomasz Abramowski, A. Bejger
Abstract
Positioning seabed objects in ultra-deep waters is critical in the mapping, exploration, and industrial exploitation of oceans. This paper presents research on a subsea wellhead positioning process for the marking of seabed positions and its subsequent as-built verification. The results indicate that the ultra-short baseline (USBL) acoustic technique can provide static positioning accuracy and precision comparable to those of a long-baseline method (LBL) and significantly reduces the time and cost of the offshore project. The new approach was tested at different stages of the process. First, an innovative offset transformation method, which increases the precision of alignments, was proposed, followed by a step-by-step procedure for determining the positions of marker buoys on the seabed based on spin tests and cardinal heading calibration. Finally, the M−estimation method, which has not yet been applied in subsea engineering, was implemented and proved to be a suitable alternative to the ordinary least squares method.