Distributed Fault Detection and Isolation Approach for Oil Pipelines

Fault detection and isolation (FDI) in oil pipeline systems (OPS) is a very critical issue because faults in these systems such as leaks or equipment malfunctions may cause significant safety accidents and economic losses. These are the challenging factors, along with the environmental regulations for developing efficient FDI approaches for OPS. This paper proposes a model-based distributed FDI approach, which uses a structural model of the system in conjunction with algorithms to generate diagnostic tests that may be implemented in local diagnosers along the OPS. The proposed approach allows detection and isolation of faults in pipeline sections (pipeline segments), pump stations, as well as process control equipment. In this way, simulation of the obtained diagnostic tests in a benchmark application shows that all faults of interest (pipeline segment faults and sensor faults) are detected and isolated.

Повышение точности прогнозных расчетов технического состояния нефтепроводов с учетом данных датчиков СОД о температуре перекачиваемой нефти

The experience of operating oil main pipelines laid underground in cryolithozone conditions shows that one of the reasons for the decrease in operational reliability of the pipeline is its thermal effect on permanently frozen ground. The parameter included in the list of initial data for predictive calculations of the technical condition of the oil pipeline is the temperature of the pumped oil, which is traditionally determined by the readings of the sensors measuring the temperature of the pipe wall of monitoring and supervisory control systems. However, the distance between these sensors can reach several tens of kilometers, so the measurements are valid only for selected sections on the pipeline segment, the shape of the temperature distribution function between them remains unknown, which negatively affects the accuracy of predictive calculations. To solve this problem it is proposed to use flow temperature sensors installed on cleaning and diagnostic facilities, with the help of which it is possible to measure the temperature of the pumped oil in each section of the pipeline. The authors set a goal to study the applicability of the results of oil temperature measurements by sensors from cleaning and diagnostics facilities to improve the accuracy of predictive calculations of thawing areolas and soil settlements at the base of main oil pipeline. In the course of the study, a series of tests was carried out using the oil temperature sensor installed on the inline inspection tool VIP 40-OPT.00-01.000 and pipe wall strap-on temperature sensor TSPU 011. According to the results of the study, the expediency of using the results of oil temperature measurements by the sensor of inline inspection tool when calculating the temperature of the pipeline wall to select the shape of the approximating function, as well as to solve related problems of geotechnical monitoring was confirmed. In order to improve the accuracy of predictive calculations of thawing areolas and soil settlements, an algorithm has been developed for checking the compliance of the calculated model of the oil pipeline with the actual pumping conditions. Опыт эксплуатации магистральных нефтепроводов, проложенных подземным способом в условиях криолитозоны, показывает, что одной из причин снижения эксплуатационной надежности трубопровода является его тепловое воздействие на многолетнемерзлый грунт. Параметром, входящим в перечень исходных данных для проведения прогнозных расчетов технического состояния нефтепровода, является температура перекачиваемой нефти, которая традиционно определяется по показаниям датчиков измерения температуры стенки трубы систем диспетчерского контроля и управления. Однако расстояние между этими датчиками может достигать десятков километров, поэтому проводимые измерения справедливы только для выбранных секций на участке трубопровода, форма функции распределения температуры между ними остается неизвестной, что отрицательно сказывается на точности прогнозных расчетов. Для решения данной проблемы предлагается использовать датчики температуры потока, устанавливаемые на средствах очистки и диагностики – с их помощью возможно производить измерения температуры перекачиваемой нефти в каждой секции трубопровода. Авторами поставлена цель по исследованию применимости результатов измерений температуры нефти датчиками со средств очистки и диагностики для повышения точности прогнозных расчетов ореолов оттаивания и осадок грунта в основании магистрального нефтепровода. В ходе исследования проведены испытания с использованием датчика температуры нефти, установленного на внутритрубном инспекционном приборе ВИП 40-ОПТ.00-01.000 и накладного датчика температуры стенки трубы ТСПУ 011. По итогам исследования подтверждена целесообразность использования результатов измерений температуры нефти датчиком внутритрубного инспекционного прибора при расчетах температуры стенки трубопровода для выбора формы аппроксимирующей функции, а также для решения сопутствующих задач геотехнического мониторинга. С целью повышения точности прогнозных расчетов ореола оттаивания и осадки грунта разработан алгоритм проверки соответствия расчетной модели нефтепровода фактическим условиям перекачки.

Effect of Coriolis Force on Vibration of Annulus Pipe

Annulus pipe conveying fluids have many practical applications, such as hydraulic control lines and aircraft fuel lines. In some applications, these tubes are exposed to high speeds. Normally, this leads to a vibration effect which may be of a catastrophic nature. The phenomenon is not only driven by the centrifugal forces, but an important role is played also by the Coriolis forces. Many theoretical approaches exist for a simple configuration or a complex three-dimensional configuration. Finite element models are tested. This paper provides a numerical technique for solving the dynamics of annulus pipe conveying fluid by means of the mono-dimensional Finite Element Method (FEM). In particular, this paper presents a numerical solution to the equations governing a fluid conveying pipeline segment, where a Coriolis force effect is taken into consideration both for fix and hinge constraint.

Implementing Genetic Algorithms to Assist Oil and Gas Pipeline Integrity Assessment and Intelligent Risk Optimization

Oil and gas industry, worldwide, needs to monitor, control and assess the elements that are involved in the general oil transportation and production processes. However, these processes are not risk free. The project proposes an intelligent support system that provides optimized projections for effective risk management. The project focuses on the development of a set of Genetic Algorithms (GAs), a branch of AI systems that assists to optimize the usage and distribution of resources. GAs will reduce the latent risks and potential dangers as much as possible. The main purpose is to minimize the risk levels in a pipeline segment based on their condition and by detecting optimal variable configurations: their Risk of Failure (RoF), Probability of Failure (PoF), Consequence of Failure (CoF), and their sub elements (threats and impacts). The heuristic results generated by this set of GAs show a significant reduction on the risk assessment measures, by finding “optimized” configurations of these variables.

Intelligent Prevention Method for Third-Party Damage of Long-Distance Pipeline Based on Mobile Devices Location Information

As one of the main risks of long-distance oil and gas pipelines, the consequences of pipeline accidents caused by third-party damage (TPD) are usually catastrophic. At present, TPD prevention approaches mainly include manual line patrol, fiber-optical vibration warning, and unmanned aerial vehicle (UAV) line patrol, but there are some limitations such as untimely warning, false alarm, and the missed report. As the location technology of mobile device matures, the user group provides massive data sources for the collection of location information, with which the tracks and features of the third-party activity along the pipeline can be directly obtained. Therefore, this paper proposes a method to identify the TPD behavior based on the location data of mobile devices. Firstly, the characteristics of relevant destruction behaviors were extracted from the historical destruction events. Then, the location information of the third-party activity near the target pipeline is obtained and the data is processed to remove the influence of noise, to reduce the computational burden of the subsequent identification process. Finally, calculate the difference degree of neighborhood trajectory and the similarity with the TPD features based on the data feature grouping (Difference feature and Similarity feature) to classify the type of third-party activity. Taking a 10km pipeline segment as an example, the method of this paper is used to preprocess the collected data and calculate the difference degree and similarity, 232 suspected TPD events are identified. After the on-site verification of the suspected damage by the line patrol, the results show that the method can better identify the third-party activities near the pipeline.

Applying Advanced Ultrasonic In-Line Inspection Technologies to Effectively Manage Hook Cracks

Axial cracking inspections have become common place on a global level within pipeline operator’s integrity management programs. As technology continues to improve, operators are presented with more accurate assessments of the assets that are in current operation. However as more information is collected more threats are being identified and need to be assessed in a manner that is more applicable to their specific morphology. It is well known that vintage ERW manufacturing techniques can suffer from a wide range of potential threats such as lack of fusion or inclusions within the steel forming hook cracks during the rolling and welding process. Current In-line inspection technologies that are designed to detect, Identify and size cracklike flaws in pipelines are very proficient at doing so. However, due to the physical principals of the Ultrasonic pulse echo technology, deep features approaching, or above pulse echo saturation amplitudes pose challenges in determining accurate depth sizing. In 2015 a Canadian pipeline operator determined the need to inspect one of their 16” assets for axial crack-like indications. During the analysis of this inspection data set, a number of saturated crack-like indications were reported. Saturated cracklike signals present a challenge to operators as they have to be considered in a conservative manner as 4mm or deeper which in turn leads to difficulties in the prioritization of resources associated with the excavation program. The operator approached NDT Global in 2017, after the release of NDT Global’s Enhanced sizing depth algorithm to reevaluate the features that were present in the previous crack inspection data set. Working together with the operator, NDT Global applied the Enhanced sizing methodology to all features of significance in the pipeline segment and compared the results to lab measurements and in field NDE measurements. The outcome of the reanalysis using the most up to date software algorithms utilizing enhanced sizing showed great benefits by increasing the accuracy of the crack depth sizing as NDT Global was now able to report full through wall depth sizing, however there were still some limitations on the ability to accurately size crack-like features as the primary threat is believed to be a result of hook cracks. As a final step in this program NDT Global was provided sample spools that were cut out of the pipeline segment to perform a pull testing campaign utilizing the newest crack detection technology that was specifically targeted towards accurately sizing tilted and skewed crack like features. The authors will briefly discuss the pipeline system and inspection campaign and in detail will discuss the benefits of using technology that has been developed to help pipeline operators better understand the threats in their integrity management program.

Deer Mountain Case Study: Integration of Pipe and Ground Monitoring Data With Historical Information to Develop a Landslide Management Plan

Deer Mountain is an active landslide complex near Swan Hills, AB. Pembina owns two pipelines that traverse the landslide. Prior to abandonment, four leaks occurred on the NPS 8 pipeline due to interaction of circumferential stress corrosion cracking and ground movement. The NPS 10 pipeline is operating and has not leaked, but has previously been strain relieved in several locations. To develop and execute a geohazard management plan for the operating pipeline, Pembina integrated pipe and ground monitoring data with historical information into a geographic information system. Locations of bending strain areas, strain gauges, pipe wall assessment (PWA) anomalies, slope inclinometers, and piezometers were cross-referenced with previous leak sites, historical dig sites, historical strain reliefs, and areas of shallow pipe burial. Overlaying the PWA with pre-existing pipe data allowed for identification of segments with a higher density/magnitude of suspected soil to pipe interactions. Strain monitoring, strain relief, and a surface pipeline segment were prescribed. A detailed monitoring plan was also produced for the landslide complex. This case study presents the process of integrating data, specifying monitoring/mitigative measures, and implementing strain relief at four locations. Additionally, the paper will discuss the design of the surface pipeline segment.

The Determination of the Limit Load Solutions for the New Pipe-Ring Specimen Using Finite Element Modeling

To estimate the acceptable size of cracks and predict the loading limit of the pipeline or its resistance to the initiation and crack growth by following the structural integrity, the fracture toughness and limit load solutions are required. Standard fracture toughness testing of thin-walled pipelines is often difficult to perform in order to complete standard requirements. To find an alternative technique for the measurement of the fracture toughness of the already delivered pipeline segment, the new pipe-ring specimen has been proposed; however, the limit load solutions have not been investigated yet. The limit load depends on the geometry of the specimen and loading mode. The ligament yielding of pipe-ring specimens containing axial cracks through the thickness under combined loads was calculated by the finite element method. This paper provides limit load solutions of several different pipe-ring geometries containing two diametric symmetrical cracks with the same depth ratio in a range of 0.45 ≤ a/W ≤ 0.55. The limit load (LL) solutions calculated by numerical analysis are shown as a function of the full ring section’s size and the corresponding crack aspect ratio for determining the normalized load. These can potentially construct the failure assessment diagram to estimate the crack acceptance in a part of the pipe.

Leakage Prevention and Real-Time Internal Detection in Pipelines Using a Built-In Wireless Information and Communication Network

Summary A series of recent pipeline leakage incidents created severe societal concerns to a point of impeding, or even completely preventing, building new pipelines in North America. Various systems have been proposed to identify and locate leakages. However, despite the fact that pipelines remain the safest means of oil and gas transportation, incidents still persist and pipeline acceptance from the public has become compromised. In order to address the need for early leakage detection, while providing comprehensive leakage prevention, a novel pipeline system is proposed. This concept builds on the already existing pipe-in-pipe design by segmenting the pipeline system with segmentation rings and embedding a linear wireless network in the annular airgap between the two pipe layers. Presence of fluid in the case of a leakage into the interpipe space causes degradation of the wireless network to a point of interrupting the communication in a particular pipeline segment well before any external leak occurs. Thus, the internal leak is detected in real time by an external central unit connected to the linear wireless network, as demonstrated with a 6 ft 8 in. experimental pipeline setup.

DETERMINING OF TRANSVERSE VIBRATION FREQUENCIES FOR CROSSOVERS AND DEAD ENDS OF GAS PIPELINES

The paper presents a stationary equation for bending deformations of a hollow rod derived by means of variational calculus. Further, the authors introduce into consideration an inertial term as consistent with a standard procedure and obtain the wave equation for pipe bending vibrations. Applying the method of separation of variables, the resulting hyperbolic equation of vibrations is reduced to an ordinary fourth-order differential equation for a standing wave on the axial line of the pipe. Fundamental solutions to the latter equation are referred to as the Krylov functions, while the standing wave is represented as a linear combination of two independent Krylov functions. The solution to the obtained homogeneous equation is only found at certain values of characteristic parameters which are amounted to a countable set for each case of fixed ends of the pipeline segment. Thus, the whole frequency spectrum of the pipe bending vibrations is determined, and the main vibration mode is revealed for each case of fixed pipeline ends.