Detailed Description :

The first phase of the study had two objectives:

• to develop a thorough understanding of all the factors involved in a successful refloat of the Maureen Platform comprising the steel gravity substructure and topsides . In parallel with this, to identify the potential risks and determine the levels of danger which the platform might sustain during the refloating operation and to formulate effective solutions to avoid or mitigate these risks;
• to develop a refloating simulator which enables a real-time visualisation of the refloating operation under various conditions, and which is suitable for quantitative risk assessment, equipment specification and training, and for publicity purposes.

Correspondingly these two objectives defined two major deliverables:

• an engineering analysis of the platform considering a number of refloat stages;
• a refloating simulator.

The engineering analysis was performed with the help of two modules: a naval architectural module to determine the hydrostatic characteristics and the motions of the platform, and a structural module to determine the structural stresses resulting from hydrostatic and hydrodynamic loads, sea bed constraints and platform accelerations. Both these modules receive their input data from a common data generation module in order to ensure full consistency and sharing of data.

The refloating simulator consists of a fourth module which receives information from both the naval architectural and structural modules and displays it in visual form on a screen.

The primary computer analysis was undertaken using the MOSES suite of programmes, with supplementary detailed finite element analysis of selected jacket nodes using ALGOR. Reference should be made to the attached computer diagrams.

Phase two of the work was intended to develop a practical refloat procedure taking into account all the potential risk scenarios. For this purpose the existing piping systems on-board the platform were reviewed for possible re-use and the following specific topics were examined;

• foundation breakout (water injection/deballasting),
• platform hydrostatic stability,
• tank deballasting,
• ballast water volume control,
• “what if” scenarios,
• pre-refloat systems and equipment checks.

Note: ode was intimately involved with the original installation of Maureen in 1983 through their parent company at that time Howard Doris.