Pipeline Leak Location Research Articles

New Sensor Cable for the Detection and Location of Leaks in Pipelines for Transportation of Hydrocarbons

At present, hydrocarbon leaks, generated mainly by corrosion of pipelines, cause large economic losses for Mexico. These leaks constitute a problem of serious consequences in Mexico and in other countries in the world. This work describes the results of the tests conducted on a new sensor cable for the detection and location of leaks in pipelines for transportation of hydrocarbons. When a liquid or gas enters in contact with the wall of the sensor cable, it causes a short circuit in the wires; changing the measurement of the resistance may detect and locate the leak. The new sensor cable that is presented in this article has advantages over cables with similar characteristic made in other countries. The use of this sensor cable in pipelines of PEMEX will avoid economic losses, environmental damage and risks of possible explosions to the population. The experimental results demonstrate these advantages.

Leak Localization in Pipelines via Computational Pipeline Monitoring

Abstract Leaks in pipelines are unintentional releases of quantities of products from pipelines into the environment. Leaks contribute to the environmental pollution, promote corrosion and equipment failures, and produce instabilities in the pipeline operation and control. Pipeline leaks are commonly associated with third party damage, corrosion, equipment failures, and errors in pipeline design and operation. Being able to accurately detect the location of leaks is imperative. One objective of this paper is to develop a mathematical model that accounts for the behavior of pressure and flow-rate profiles in leaky pipeline systems. Such a mathematical model is needed to better understand the dynamic behavior of the pipeline and its characteristics and for the detection the leaks. The paper also involves computer simulation of pipeline conditions using the developed mathematical model and Kalman filtering technique. Leak localization is accomplished by scanning the pipeline from the inlet node to the outlet one to find the node at which the minimum residuals are obtained. Simulation results are reported to demonstrate the effectiveness of the proposed leak localization scheme.

System Response Function–Based Leak Detection in Viscoelastic Pipelines

The possibility of leak detection in a viscoelastic pipe system is studied. The frequency response function method (FRFM) is used for leak detection, and the analytical expression for the FRFM originally developed for an elastic pipeline is extended to the viscoelastic situation in this study. The extended FRFM is validated from numerical experiments with one-dimensional viscoelastic transient models. The analysis shows that the pipe-wall viscoelasticity effect has significant impact on the amplitude damping and phase shift of the pressure wave, but little influence on the leak-induced patterns of pressure head peaks in transient system frequency responses. The results indicate that the extended FRFM is applicable to the viscoelastic situation. The impact of viscoelastic parameters and incident wave bandwidth on the applicability of the extended FRFM i also investigated in this paper, and the results imply that transient input signals with rapid changes in time are preferable for leak location in viscoelastic pipelines.

The Research of Oil Pipeline Leak Detection and Location Based on PVDF Piezoelectric Sensors

This paper mainly deals with the problem of oil pipeline leak and difficult to detect its location, combining the trait of our country’s oil pipeline, researching the leak detection and location based on the PVDF piezoelectric sensors. This paper firstly describes the domestic status of pipeline leak detection, and then gives a brief introduction for the PVDF piezoelectric film, finally discusses the pipeline leak detection and location system based on PVDF piezoelectric sensors. Experiments show that the use of PVDF piezoelectric sensors on pipeline leak detection, the leak can be correctly identified, and improving the detection sensitivity and leak resolution, effectively reducing the false alarm rate.

Leak location in pipelines using the impulse response function

Current transient-based leak detection methods for pipeline systems often rely on a good understanding of the system—including unsteady friction, pipe roughness, precise geometry and micro considerations such as minor offtakes—in the absence of leaks. Such knowledge constitutes a very high hurdle and, even if known, may be impossible to include in the mathematical equations governing system behavior.An alternative is to test the leak-free system to find precise behavior, obviously a problem if the system is not known to be free of leaks. The leak-free response can be used as a benchmark to compare with behavior of the leaking system. As an alternative, this paper uses the impulse response function (IRF) as a means of leak detection. The IRF provides a unique a relationship between an injected transient event and a measured pressure response from a pipeline. This relationship is based on the physical characteristics of the system and is useful in determining its integrity. Transient responses of completely different shapes can be directly compared using the IRF. The IRF refines all system reflections to sharp pulses, thus promoting greater accuracy in leak location, and allowing leak reflections to be detected without a leak-free benchmark, even when complex signals such as pseudo-random binary signals are injected into the system. Additionally, the IRF approach can be used to improve existing leak detection methods. In experimental tests at the University of Adelaide the IRF approach was able to detect and locate leaks accurately.

Leak location in single pipelines using transient reflections

The use of controlled, small amplitude transient (water hammer) signals for the detection of leaks in pipeline systems is a promising area of research. A pressure transient travels along the system at high speed and is modified by the system during its travel. Leaks within a pipeline partially reflect these pressure signals and allow for the accurate location of a leak by tracing the reflection to its source – a technique commonly known as time domain reflectometry. This paper discusses and provides possible solutions to a number of practical issues associated with leak detection methods of this type, including the impact of the system configuration and methods for detecting leak reflected signals within a transient trace. A set of equations has been derived to locate leaks in a pipeline for all locations of the transient source and measurement stations, and is essential for an automated monitoring system that uses more than one simultaneous measurement of the transient signal. A change detection algorithm is used in this paper to provide an automated approach for detecting leak reflections, which can reduce the ambiguity associated with simple visual inspection of the transient trace. This procedure was validated by both operational and offline (pipeline shutdown) experimental tests conducted at the University of Adelaide.

Neural net versus classical models for the detection and localization of leaks in pipelines

Four models of a pipeline are compared in the paper: a nonlinear distributed-parameter model, a linear distributed-parameter model, a simplified lumped-parameter model and an extended neural-net-based model. The transcendental transfer function of the linearized model is obtained by a Laplace transformation and corresponding initial and boundary conditions. The lumped-parameter model is obtained by a Taylor series extension of the transencdental transfer function. Based on the experience of linear models the structure of the neural net model, as an addendum to the nonlinear distributed-parameter model, is obtained. All four models are tested on a real pipeline data with an artificially generated leak.

Modal analysis of acoustic leak signal in pipelines using time-frequency analysis

It is important to analyze the propagation characteristics of guided waves in acoustic leak location in pipelines. In this paper, the acoustic leak signal is analyzed in the time-frequency domain. Based on the relation of time-frequency distribution of the acoustic leak signal and the dispersion curves of guided waves, the mode components of acoustic leak signals were obtained. The research can provide a guideline for the mode selection in pipeline leak location, and help improve the accuracy of leak location.

A new technique for modal acoustic emission pipeline leak location with one sensor

Due to the multi-mode and dispersion characteristics of acoustic wave propagation in a pipeline, traditional crosscorrelation techniques do not perform well for acoustic leak location. Based on the theory of modal acoustic emission (MAE), a technique of MAE pipeline leak location with one sensor is proposed. With the dispersion characteristics of guided wave propagation in pipe, two modes in the acoustic leak signal are isolated. Using the two modes isolated from one sensor, a leak location model is proposed. Leak location experiments have proved the validity of the one sensor MAE pipeline leak location technique.

A non-linear multiple-model state estimation scheme for pipeline leak detection and isolation

Model-based monitoring schemes are known to have a great potential in detection and localization of leaks in pipelines. Fluid flow in pipelines is characterized by a system of non-linear-coupled partial differential equations. Since state estimation can provide the basis for real-time monitoring of fluid flow in pipelines, a suitable numerical scheme is employed to formulate the problem in state-space form, which enables the development of state estimation techniques. A modified extended Kalman filter (MEKF) in conjunction with feed forward computations to anticipate the leak magnitude provides the core of the adaptive multimodel state estimation technique used in this paper. Numerical simulation results show that the developed state estimation scheme effectively detects and locates small leaks in pipelines within a short time duration.

A non-linear multiple-model state estimation scheme for pipeline leak detection and isolation

Model-based monitoring schemes are known to have a great potential in detection and localization of leaks in pipelines. Fluid flow in pipelines is characterized by a system of non-linear-coupled partial differential equations. Since state estimation can provide the basis for real-time monitoring of fluid flow in pipelines, a suitable numerical scheme is employed to formulate the problem in state-space form, which enables the development of state estimation techniques. A modified extended Kalman filter (MEKF) in conjunction with feed forward computations to anticipate the leak magnitude provides the core of the adaptive multimodel state estimation technique used in this paper. Numerical simulation results show that the developed state estimation scheme effectively detects and locates small leaks in pipelines within a short time duration.

System for detection of the location of leaks in gas pipelines of low pressure

The principle of operation of a system based on correlation of noise arising at locations of the loss of tightness of a pipeline is described. Acoustic noise received by transducers mounted at the end-points of the controlled section of the pipeline are amplified, filtered by band-pass filters, and coded. The digital data is transmitted to a PC and the measurement results are displayed on a screen in the form of the correlation curves with coordinates of the leakage location of the gas in the pipeline.

A mathematical model for leak location in pipelines

In the present paper, a novel method for leak detection in pipelines is described. The method is based on a unidimensional flow analysis. The theoretical findings have been verified experimentally for two different hole geometries (circular and rectangular). The comparison set between theory and experiment confirms the physical realism of the mathematical model. The accuracy in calculating the leak position is estimated to be less than a few percent for the different hole geometries in question.

Leak detection, timing, location and sizing in gas pipelines

A method is described of detecting leaks in gas pipelines by use of flow, pressure and temperature measurements that are usually made in long-distance natural gas pipelines for other reasons. Once a leak has been detected, the time at which leaking began, the location and the size of the leak is immediately available. The method is based on an accurate simulation of the transient hydraulic behaviour of the pipeline and makes use of all the measurement data available. The method has been tested with simulated data from the Dampier to Perth natural gas pipeline and it is shown that leaks as small as 2% of design flow can be detected in 2.5 h, even in the presence of severe transients and 20 kPa random error in all pressure measurements.

Leak detection and location in gas pipelines

Describes a new method for detecting and locating leaks in long pipelines, based on an extended Kalman filter for the nonlinear distributed parameter system representing gas flow in pipes. Artificial leak states at predefined positions along the pipeline are included in the filter model, and relationships to estimate the actual leak position are derived. Simulation results are presented to assess the method.< >

Leak detection methods for pipelines

For the early detection and localization of small leaks in pipelines a nonlinear adaptive state observer and a special correlation technique were developed, based on pressure and flow measurements at the pipeline inlet and outlet. Simulations and experiments show the results for a gas and a liquid pipeline.

Leak Detection Methods for Pipelines

For the early detection and localization of small leaks in pipelines a nonlinear adaptive state observer and a special correlation technique were developed, based on pressure and flow measurements at the pipeline inlet and outlet. Simulations and experiments show the results for a gas and a liquid pipeline.