Developing an Intelligent Sensor for Monitoring Pipeline-System Integrity
Authors: Denney Dennis 
Published: February 2015

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 115503, "The Development of an Intelligent Sensor for the Monitoring of Pipeline-System Integrity," by Bonny B.N. Umeadi and K.G. Jones, University of Greenwich, UK, prepared for the 2008 SPE Russian Oil and Gas Technical Conference and Exhibition, Moscow, 28-30 October. The paper has not been peer reviewed.
Current methods of pipeline-leak detection rely on periodic inspection, which misses more occurrences of failure than it identifies. A semicontinuous-monitoring system could recognize imminent pipeline-failure characteristics and automatically transmit a warning to a central control center. This paper reports findings of a laboratory-based test program to evaluate the potential for vibration-sound-emission detection to form the basis of such an early-warning system.

Introduction
Integration of innovative technology into new construction is daunting, but the majority of the pipeline infrastructure that will be in use in 2025 in the UK already exists, so many of the innovative technological solutions will have to be retrofitted to existing facilities. Therefore, a greater understanding of the operational and strategic characteristics of the pipeline infrastructure will be required. This research addressed this challenge by developing a new approach to maintenance planning for oil-pipeline-distribution systems.

Monitoring Oil-Pipeline Systems
Much of today's oil is produced in remote areas and transported through a vast pipeline network (more than 1 million miles), which is aging and prone to localized failures. Recent high-profile oil-pipeline leakages in Alaska; sabotage in Nigeria, Iraq, and Russia; and the explosion at the Buncefield complex in North London have focused the industry's attention. These incidents also alerted the world's news media to the problems associated with oil-/gas-pipeline integrity and, in particular, with the inspection processes for pipeline-distribution systems. Current inspection systems are based on either destructive or nondestructive approaches.
Destructive tests involve a section of pipeline being isolated, pressurized, and monitored to ensure no leaks exist. However, this approach disrupts the pipeline's normal operation, so it generally is used only for the initial inspection and not after the pipeline has been commissioned. Once a pipeline is in service, it is normal to use a non-destructive-testing (NDT) approach. Magnetic-flux-leakage and ultrasonic-guided-wave methods are the two predominant nondestructive methods used for testing pipeline integrity.
Vibration/acoustic emissions are another NDT technique that can identify defects in structural (pipeline) systems at their initiation stage and characterize their vibration/acoustic-emission activity as they progress into their critical stage. The methods have been used successfully for testing both composite and metal structures. Their global nature enables inspection of large and complicated infrastructures with few sensors and without the need for manual scanning and access to the inside of the structure. However, the calculations underpinning these systems use long-wave-length propagation theory, which is not appropriate for the detection of internal cracking associated with pipeline-distribution systems. What is needed is a monitoring system that monitors pipeline integrity continuously, without affecting the pipelines production capacity, and that is no more expensive than current NDT methods in use by the industry.