A Case Study of Reliability Analysis of the Deep-Water Disposal (DWD) Pumps in an Oil Plant

Soud Al-Toubi¹, Alkali B.¹, Harrison D.¹, and Sudhir C. V.²

1. Secretaria-Geral da Presidência da República, Portugal

2. Faculdade de Arquitectura Universidade de Lisboa, Portugal

Abstract: Deep Water Disposal (DWD) pumps are widely used in the Oil and Gas industries, and their primary function is to dispose of produced water that is associated with oil and gas production process. The DWD is vital to the smooth operation, and they represent a significant segment of the entire operation. High reliability of these pumps is envisaged to reduce the maintenance cost (failure cost), and thus reduce the process disruption and also ensure continuous plant productivity, which reflects positively on the revenue generated. This paper discusses the reliability measures of 12 identical DWD pumps in an oil and gas plant that has been in operation for more than 15 years. The underlying analysis investigates the failure frequency from the time of commissioning till date, and historical data analysis using the Pareto 80/20 rule shows an excellent insight to the DWD system performance. The current state of the pump system performance observed is decreasing based on the number of failures that occurred during the specified operating period. The paper discusses the reliability and failure analysis of three main systems viz: motor, Gearbox and Mechanical pump assembly of DWD pump. A fishbone analysis approach was used to identify 12 categories of the DWD pump failures causes, and each category has led by several problems or causes at some point during operation. Reliability analysis for the three various systems conducted to ascertain which system has the highest number of failures (low reliability) and the effect on the entire system performance shows that the Mechanical pump assembly has poor reliability and the highest maintenance cost. To complement the reliability analysis conducted the failure cost analysis, and the losses of a significant portion of the maintenance expenses are approaching.

Key words: reliability, failure cost, Pareto rule, performance, DWD pump, fishbone analysis