Gas Pipeline Leak Detection Research Articles

Phase distortion analysis and passive demodulation for pipeline safety system based on Jones matrix modeling

Phase distortion happens in the distributed optical fiber oil and gas pipeline leak detection and early warning system, which results in decreased sensitivity of the system and bigger location errors. This paper studies the birefringent characteristic of the optical fiber interferometer sensing arm, and the Jones matrix model of the optical polarization is established. On the basis of this model the optical path and location principle are improved by using two 3 × 3 couplers to acquire four light signals. Then, the demodulation method is adopted to get phase differences induced by perturbation of the two reverse optical paths, which are used subsequently in cross-correlation algorithm to achieve the time-delay estimation. Compared to the method of polarization control, this approach simplifies the system structure and reduces the cost. The trial results show that this method not only eliminates the effect of the phase distortion but also improves the system’s accuracy and locating stability.

激光遥测天然气泄漏定位算法研究及应用

天然气管道泄漏检测对人员安全、环境保护以及国家财产安全等方面具有重要的意义。但是，由于管线跨越地域广阔，操作工况以及环境情况复杂，致使管线的泄漏检测存在困难。采用激光吸收光谱技术对天然气泄漏进行了定量遥测与定位研究，具有快捷、准确、智能及安全等特点。本文重点介绍了在无合作目标背景下激光遥测天然气泄漏定位算法研究。实验模拟了激光移动遥测天然气泄漏定位、泄漏扩散方向判别及泄漏总量获取等，在低浓度遥测时总量获取的误差从55.89%降到7.41%，在动态模拟泄漏中，通过移动最小二乘法曲面拟合滤波与图像区域分割可以准确获得泄漏源的位置，以及判别的气体扩散方向与实际基本吻合。结果验证本文的泄漏定位算法适合天然气泄漏的遥测定位，为天然气泄漏检测提供一种新的诊断方法。 The natural gas pipeline leakage detection is significant in terms of security, environmental protection and security of state property. However, the leak detection is difficult, because of the pipeline’s covering many areas, operating conditions and complicated environment. Quantitative remote sensing of natural gas leakage and location research, with laser absorption spectroscopy, will be faster, safer, more accurate and intelligent. This article focuses on locating algorithm for laser remote sensing of natural gas leakage in the case of non-cooperative target. Leakage locating, the direction of gas diffusion and total leakage were obtained through the simulation experiments. Relative error, dropped from 55.89% to 7.41% by a total leakage simula-tion of trace methane. The results of leak location and gas diffusion direction are consistent with the actual’s by moving least square method and image segmentation through the dynamic leakage simulations. Locating algorithm is feasible by analyzing the experimental simulation of the natural gas leakage, and it will become a new diagnostic method.

Designing a reliable leak bio-detection system for natural gas pipelines

Monitoring of natural gas (NG) pipelines is an important task for economical/safety operation, loss prevention and environmental protection. Timely and reliable leak detection of gas pipeline, therefore, plays a key role in the overall integrity management for the pipeline system. Owing to the various limitations of the currently available techniques and the surveillance area that needs to be covered, the research on new detector systems is still thriving. Biosensors are worldwide considered as a niche technology in the environmental market, since they afford the desired detector capabilities at low cost, provided they have been properly designed/developed and rationally placed/networked/maintained by the aid of operational research techniques. This paper addresses NG leakage surveillance through a robust cooperative/synergistic scheme between biosensors and conventional detector systems; the network is validated in situ and optimized in order to provide reliable information at the required granularity level. The proposed scheme is substantiated through a knowledge based approach and relies on Fuzzy Multicriteria Analysis (FMCA), for selecting the best biosensor design that suits both, the target analyte and the operational micro-environment. This approach is illustrated in the design of leak surveying over a pipeline network in Greece.

天然气管道泄漏激光遥感探测系统的研制及标定方法

天然气管道泄漏激光遥感探测系统的研制及标定方法

Model-Based Monitoring and Leak Detection in Oil and Gas Pipelines

Summary An adaptive Luenberger-type estimator for the purpose of monitoring flow conditions and locating and quantifying leakages in petroleum pipelines is presented. The estimator only needs measurements of velocity, pressure, and temperature at the inlet and velocity and pressure at the outlet to function. The measurements are used to form a special set of boundary conditions for the estimator that ensures fast convergence of the estimation error. Depending only on measurements from inlet and outlet makes it possible to use OLGA, which is a state-of-the-art computational fluid dynamics simulator, to govern the one-phase fluid flow of the estimator. The estimator is tested with both a straight, horizontal pipeline and an actual, long pipeline with inclinations, and both simulations with oil and gas are carried out. In order to cope with modeling errors and biased measurements, estimation of roughness in the monitored pipeline is introduced.

Gas analysis within remote porous targets using LIDAR multi-scatter techniques

Light detection and ranging (LIDAR) experiments are normally pursued for range resolved atmospheric gas measurements or for analysis of solid target surfaces using fluorescence of laser-induced breakdown spectroscopy. In contrast, we now demonstrate the monitoring of free gas enclosed in pores of materials, subject to impinging laser radiation, employing the photons emerging back to the surface laterally of the injection point after penetrating the medium in heavy multiple scattering processes. The directly reflected light is blocked by a beam stop. The technique presented is a remote version of the newly introduced gas in scattering media absorption spectroscopy (GASMAS) technique, which so far was pursued with the injection optics and the detector in close contact with the sample. Feasibility measurements of LIDAR-GASMAS on oxygen in polystyrene foam were performed at a distance of 6 m. Multiple-scattering induced delays of the order of 50 ns, which corresponds to 15 m optical path length, were observed. First extensions to a range of 60 m are discussed. Remote observation of gas composition anomalies in snow using differential absorption LIDAR (DIAL) may find application in avalanche victim localization or for leak detection in snow-covered natural gas pipelines. Further, the techniques may be even more useful for short-range, non-intrusive GASMAS measurements, e.g., on packed food products.

Overview: Production/Facilities (December 2007)

It does not seem a year since the last facilities feature. The theme this year is about heavy-oil upgrading to light oil; although a paper about wax seems to have slipped in too. Heavy oil is an enormous energy resource that still is largely untapped. The challenge is to get the stuff out of the ground as fast as the lighter oil that we currently produce. Unfortunately, the density and viscosity usually make this target very difficult in the end. However, heavy oil is not all bad; on a volume basis, it contains more energy than lighter oil. Currently, the industry is attempting to justify heavy-oil developments on two fronts: by developing new means for extracting it faster and by increasing its value. This is where the real prize is in heavy oil—its value. Its value currently is largely unrecognized; it sells often much cheaper than lighter oil even though it contains more energy on a volume basis. The industry is currently developing ways to upgrade it to light oil to add value; but there are other ways of adding value, and to find these, one must re-examine the business model of the upstream industry that has not changed in 150 years. We continue to produce and sell crude oil to refiners and let the oil traders set the price. We can, and should, be more proactive in finding ways to exploit the irreplaceable value of oil. Production/Facilities additional reading available at the SPE eLibrary: www.spe.org SPE 107958 "Modeling Rapid Multiphase Flow in Wells and Pipelines Under Nonequilibrium and Nonisothermal Conditions" by Guillermo Michel, University of Oklahoma, et al. SPE 108752 "A Study of Normal Slug Flow in an Offshore Production Facility With a Large-Diameter Flowline" by E. Guzmán Vázquez, National Autonomous University of Mexico, et al. SPE 104133 "Leak Detection for Gas and Liquid Pipelines by Transient Modeling" by Shouxi Wang, Gas Liquids Engineering, et al.

Leak Detection for Gas and Liquid Pipelines by Online Modeling

Summary The leakage of hydrocarbon products from a pipeline not only represents the loss of natural resources, but it also is a serious and dangerous environmental pollution and potential fire disaster. Quick awareness and accurate location of the leak event are important to reduce losses and avoid disaster. A leak-detection method using transient modeling is introduced in this paper. This method is suitable for both gas and liquid pipelines, with comprehensive consideration of the transient-flow features of compressible flows and stochastic processing and noise filtering of the meter readings. The correlations for diagnosing the leak location and amount are derived on the basis of the online real-time observation and the readings of pressure, temperature, and flow rate at both ends of the pipeline. As an online real-time system, great attention has been paid to the stochastic processing and noise filtering of the meter readings and the models to reduce the impact of signal noise. It is also essential for the robust realtime pipeline observer to have the self-study and adjustment abilities needed to respond to the large varieties of pipeline configuration, pipeline operation conditions, and fluid properties. Real application cases are presented here to demonstrate this leak-detection method. For example, in the leak detection of a crude-oil pipeline of 34.5 km long and 219 mm (nominal diameter), this method located the leak at 16.6 km from the pipe-line upstream end, which is only 0.6 km away from the actual leak location.

Gas pipeline leak detection system using the online simulation method

Management of natural gas pipeline is an important task for economical and safety operation, loss prevention and environmental protection from methane emission. A leak detection of gas pipeline, therefore, plays a key role in the overall integrity management for a pipeline system. Especially for a long pipeline operated alongside of densely populated areas, a leak detection system is an indispensable condition to allow its construction. In this paper, a leak detection method based on a dynamic simulation with wave equations is presented. An industrial application to one of the longest gas pipeline is also presented with its performance information.

Better leak detection in gas pipelines

Two further developments in the method of leak detection in gas pipelines described in an earlier work by Turner and Mudford are presented. First a method is given of optimizing the use of the available data such that leaks can be detected sooner, giving a factor of 3 or more improvement for small leaks. Second a number of results concerning the effect of variable leak size on the determination of the time at which leaking began are obtained analytically.

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.< >