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Figure 3.6 – Gravity-Paled Structure

3.1.4 Classification of fixed offshore structures. Consequently, the above

constructs can be defined as rigid (Hardening) and categorized (indicating the

prevalence in the world) them as follows.

* Hardening Structures – 76% (natural period 3 – 6 s):

1. Jacket Structures (including Pier Platforms and

Minimal Platforms) – 45%

2. Gravity Base Structures – 26%

3. Gravity-Paled Structures – 5%

3.2 Compliant Towers (24%), consist of narrow, flexible towers and a piled

foundation supporting a conventional deck for drilling and production operations

(fig. 3.7). Compliant towers are designed to sustain significant lateral deflections

and forces, and are typically used in water depths ranging from 1,500 and 3,000

feet (450 and 900 m). Natural period -20-120 s.

The definition of a compliant structure includes those structures that extend to

the ocean bottom and directly anchored to the seafloor by piles and/or guidelines.

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