Reliability Engineering Applied to Offshore Petroleum Production System
Authors: Ingram Gerald E. , Dee Philip A. 
Published: October 2008

1 INTRODUCTION

Since the invention of the Wheel, man has worked to develop systems that were reliable as well as functional. Until the end of World War II however, the bulk of his efforts in reliability enhancement were devoted to making his equipment bigger and stronger to withstand the effects of heavier loads and more hostile environments. Unfortunately, there was no satisfactory way of measuring or quantifying this seemingly elusive characteristic. Designs were based upon past experience and very often on inadequate data. Many of these reliability improvement efforts achieved some measure of success in prolonging the operating life of the equipment, but the associated costs were distressingly high; and reliability overkill or unfavorable economic balance resulted.

In the last twenty-five years, a new discipline has found increasing application within governmental and industrial communities. Reliability engineering, proven in an outstandingly successful space program, is an integral requirement in virtually every significant military or space procurement. The techniques of reliability engineering and measurement are used extensively by the safety-conscious, commerical aircraft manufacturers. The intensely competitive automotive industry has enjoyed the benefits of reliability analyses for many years. The public utilities have long recognized the need for reliability measurement and prediction. Recently, the petroleum industry has identified the need for measuring production equipment reliability from the standpoint of potential pollution as well as profit enhancement.

II RELIABILITY DEFINED

Reliability is defined as:The probability that a system will operate satisfactorily, for a specific period of time under stated conditions.Consequently, satisfactory system operation, time and conditions of use are the essential elements of reliability quantification.

II I ANALYSIS OUTPUTS

Traditionally, in reliability analysis, the principal output is a number between 0 and 1 which satisfies the definition of reliability as stated above. This number, however suitable for measuring the reliability of many types of systems, does not provide a unit operator with an indication of the penalties he must pay for each failure. For example: a platform production system may have a reliability of .2. At first glance, this appears to be an extremely unreliable system. It may well be, however, that the failures producing this apparently low reliability are of relatively little significance, i.e., they cause no pollution, negligible shut in time, and small repair costs. Therefore, the operator may derive little or no benefit from an expenditure to improve the reliability of his facility. Conversely, a reliability of .95 indicating relatively few failures, could conceal a small number of disasterous failure events creating catastrophic consequences. Given this situation, the operator would benefit materially from a reliability improvement program.

The "Event-Consequence" approach to reliability analysis was developed especially for the unique problems of the petroleum industry.