The Spar Platform - Transforming Deepwater Development

摘要

This paper reviews the evolution of spar designs, focusing on the progression of work that ultimately lead to the application of this new concept to the oil industry-. This papers updates and expands on a previous paper by one of the co-authors. This paper discusses the evolution of spar designs from "classic" deep draft caisson designs to the truss spar and the cell spar. The paper discusses the reasons the spar was successful in the first place, and how its design has been tailored to varying field development requirements over the years. It discusses specific considerations in supporting risers from spars, and the unique motion characteristics in waves and currents. The simplicity of the early spar hulls is discussed. Finally, the role of key players especially the inventor Ed Horton that helped make the history of the spar a successful one is discussed. The spar is the only successful dry tree solution for deep water production that can successfully operate in the deepest fields today and in the most severe environments. Its deep draft results in natural periods outside the range of waves, which has led to its wide acceptance for different field scenarios. The largest disadvantage of the spar is arguably the logistics of deck installation, which normally requires an offshore heavy lift. The paper discusses the research that was done on heavy topsides floatover for the spar, and the successful floatover operations both offshore and inshore. The paper provides a unique look at the history and evolution of this concept showing how the idea originated and how the design was improved and adapted as data on its performance became available and new requirements emerged.