Application of Reliability Analysis Techniques to Intelligent Wells
Authors: Drakeley Brian K. , Douglas Neil I. , Haugen Knut E. , Willmann Endre 
Published: October 2008

This paper describes the overall methodology and quantitative techniques applied during the development of an Intelligent Well control and communication system in order to ensure high system reliability and availability. In particular, the anticipated reliability impact of introducing high temperature electronics technology together with redundancy for critical components is quantified.

One of the main challenges when analyzing the reliability performance of novel technology is to establish appropriate input data. Hence, a methodology applied to establish and validate reliability data is presented.

Harsh installation and operating conditions make a zero failure expectation over a 10-year life span appear unrealistic. The solution to this paradox is to assume that there will be some failures and to combat this by developing a highly faulttolerant system.

The methodology described in this paper also has broader potential applications to other oil and gas system development projects. It brings to our industry practices that are frequently employed in the aerospace and nuclear industries.

Introduction

A widely accepted definition is that an Intelligent Well is one that has all three of the following capabilities:Flow Segregation. Individual zones/laterals in a well are isolated from each other and flow (production or injection) out of or into them can be remotely controlled by means of downhole flow control device (FCD).Well Parameter Monitoring. Well bore and/or reservoir characteristics (e.g. P,T,Q) can be remotely monitored in real time.Well Performance Optimization. The well bore characteristics are evaluated and the knowledge gained is actually used to determine if any of the FCDs should be adjusted in order to maximize the overall performance of the well. The evaluation is performed manually at present but in the future it could be via a closed loop operation.

It is also widely accepted that an Intelligent Well can provide added value in a number of areas. Briefly, the benefits may include one or more of the following:increased recoveryreduced well construction costsaccelerated production profilesreduced well intervention frequency and costs (also resulting in improved operational safety)

However, the economic gains offered by any Intelligent Well system are illusory unless the equipment proves reliable in service. For example, in subsea well applications, repair is an extremely expensive option, and yet it is the subsea well applications where the operators currently have the most to gain.

The overall objective of the subject Intelligent Well reliability project has and continues to be to ensure the provision of satisfactory system reliability and operational performance on a long-term basis for all well applications, including HP/HT. To achieve this objective, systematic component criticality assessments and reliability performance simulations are applied as decision support tools during the design process. This ensures that the end design is "reliability driven" and that any "reliability killers" have been eliminated.

An increasing number of oil and gas operating companies have already taken the bold step of deploying Intelligent Well systems. By the end of the year 2000 such systems had been deployed in over thirty wells, worldwide.