Fixed Offshore Platforms Topside Facilitiessafety Criteria And Evaluations
Authors: Hauan Oystein 
Published: March 2010

Introduction

"Topside" of fixed production facilities requires a multi-discipline approach. A range of safety criteria has been developed for the complex integrated production platforms in the North Sea and is still being improved. Safety evaluations are being performed at all stages of platform development. The British and Norwegian standards are guidelines for the offshore industry. This paper deals with:Risk Analysis Applied to Topside FacilitiesSimultaneous Platform OperationsTopside Systems and Hardware

Risk Analysis Applied to Topside Facilities

This is an evaluation methodology which deals with undesirable, unexpected and unscheduled events in various forms and to ever-increasing cases. The most frequent use in the North Sea has been during the conceptual design phase with modifications during detailed design and then when operating.

The "core" of risk analysis is to establish the risk level, the probability of the events. Undesirability is expressed as the physical consequences and/or cost. "Risk Analysis" can take on many different forms, ranging from comprehensive studies to simple evaluations and calculations. There are two types:choice between two or more alternatives, andaccept/reject.

The latter is typically the authorities' decision problem involving an acceptance criterion; (a) also requires some decision criteria in the form of optimization.

A second dimension which has a bearing on the risk analysis is the decision level. The perceptions of the designer, operator, manager and politician are obviously different.

The third dimension is the project phase. The risk analysis approach in the conceptual phase will be different from the operational phase. This is partly due to the change in type of decision and available information.

Most of the risk analyses by VERITAS involving topside facilities have been related to the conceptual and design phases. This is where most freedom exists and where the fundamental decisions are taken. In Norway the Petroleum Directorate (NPD) requires a formal Concept Safety Analysis as a part of Field Development Plan. Operators often use this opportunity to perform an analysis far beyond the requirements of NPD.

VERITAS sees risk analysis applied in three sequential steps or levels for a typical offshore field development:General arrangement of platforms to develop an offshore field.General arrangement of individual platforms.Arrangement of the facilities on the individual platform.Field development planning involves the relative location, specific functions and rough layout of the individual installations.

The significant credible accidents liable to happen in the different areas of the platforms are identified in a systematic manner and the effects are estimated.

These analyses can rate different alternatives and measure against established acceptance criteria. An evaluation of main safety functions is often included as a part of the selected general platform arrangement. The identified accidental effects within each platform area and the quality of the main safety functions, against established acceptance criteria (e.g. for fire walls and detection/ extinction systems expressed through National Regulations and recognized codes and standards) are measured.