Ultimate Strength Performance of a Novel Self Installing Platform Concept

Pinna, Rodney (School of Oil & Gas Engineering, The University of Western Australia) | Cole, Geoff (School of Oil & Gas Engineering, The University of Western Australia) | Murphy, David (School of Oil & Gas Engineering, The University of Western Australia) | McKay, Stuart (INTEC Engineering)

OnePetro 

ABSTRACT

Installation is a major cost component of offshore oil and gas platforms, particularly in remote regions, where infrastructure may need to be brought in at great expense. This may be a critical issue for marginal field developments where infrastructure mobilisation costs may be prohibitive. One method of reducing this cost is by employing selfinstalling platforms. This paper outlines a self-installing guyed tower concept suited to marginal field developments and examines its ultimate strength performance and long-term structural reliability. A preliminary reliability analysis indicates that, in common with some other minimum facilities platforms, structural design would need to exceed the requirements of API RP2A to provide adequate long-term structural reliability for unmanned operations.



INTRODUCTION

Installation costs are a key component of offshore oil and gas developments, particularly those in remote regions where the cost of mobilising installation infrastructure can be prohibitive. One method of reducing installation costs under these circumstances is by employing self-installing platforms. While self installing options such as production jack-ups and concrete gravity base structures are now proven concepts for moderate to large fields (Baerheim et al., 1999, Wallis and Jackson, 1999), there is relatively less experience with self installing minimum facilities which are suited to smaller, marginal field developments. However, the innovative use of spar buoys for marginal oil and gas field development demonstrates that carefully planned self installing concepts can lead to successful project outcomes (Campbell et al., 1996). It is well understood that following well accepted offshore structural design codes (such as API RP2A) leads to varying levels of long-term structural reliability of offshore platforms across different regions (Turner et al., 1992). More recently, it has been shown that the use of API RP2A may not provide adequate reliability for some minimum structural configurations on the North West Shelf of Australia (Ronalds et al., 2003a,b&c).