Development of an Integrated Availability Model for ADCO's Availability Assurance Program

Abstract

ADCO operates and manages an expanding system of on-shore crude oil producing assets in the Emirate of Abu Dhabi - U.A.E. To assess the future Effective Capacity, track the actually achieved Effective Capacity and forecast the Effective Capacity for each forthcoming year, the company employs an Integrated Availability Model.

The model was initially developed in 2002-2003, using a Shell GSI software product called SPARC to assess the future Effective Capacity for an expansion project. Three years later it was further developed for another expansion project. In 2006-2007 the model was upgraded to capture the actual downtime events of individual strings/wells and the critical surface facilities for System Availability tracking purpose. In 2009 the model was further developed to support planning task that includes synchronization / optimization of major shutdowns planning and forecast the Effective Capacity and the System Availability for each forthcoming year.

The assessment, tracking and planning tasks are the core activities of the ADCO's Availability Assurance Program which objectives include improvement of the average System Availability towards 95%.

This paper describes how the model is gradually developed and utilized by showing relevant charts, processes and result examples.

Introduction

The Integrated Availability Model is basically a Reliability Block Diagram (RBD). It incorporates blocks which represent units or equipment that are critical for crude oil production. The units includes sub-surface facilities (reservoirs/wells) and surface facilities at each asset, downstream gas handling facilities, the Main Oil Lines, downstream refineries, down stream petrochemical plants and the oil export terminal.

The blocks are in parallel or in series representing various subsystems. In turn, these subsystems are in parallel or in series with each other and the remaining units representing the whole integrated crude oil production system.

The model has been developed in phases to support the following tasks:                                                           

1)       Assessment, for expansion projects

2)       Tracking, for quarterly System Availability KPI reporting

3)       Planning, for annual System Availability KPI forecasting

For each task, the model is used to calculate the Maximum Capacity, Effective Capacity and Availability of the whole system and its main subsystems.

The units' downtime data that are used in the calculations for each task are from different nature and are different in the way they are entered into the model. The pre-calculation set up, before running the SPARC software, is also unique for each task.