Oil Gas Pipelines Research Articles

Performance Evaluation of Different Short Path Algorithms to Improve Oil-Gas Pipelines

The oil-gas pipeline is a complicated and expensive system in terms of construction, control, materials, monitoring, and maintenance which includes economic, social and environmental hazards. As a case study of Iraq, the system of pipelines is above the ground and is liable to disasters that may produce an environmental tragedy as well as the loss of life and money. Hence, this article presents a performance evaluation of different short path algorithms to improve oil-gas pipelines. The chosen algorithms in this paper were Parallel Short Path Algorithm (PSPA), Ant Colony Optimization (ACO) algorithm and Genetic Algorithm (GA). The main performance metric is the cost of the pipelines. Simulation trials were performed using the MATLAB program for the chosen algorithms. The performance comparison showed that the lowest cost of laying oil and gas pipelines was by applying the GA algorithm when the number of wells was set to 50-600. Conversely, the PSPA algorithm showed the best performance in terms of required implementation time for all scenarios. Besides, PSPA appeared to have acceptable performance in terms of the cost of the pipeline when the number of wells was arranged between50-600. Furthermore, PSPA showed the best performance for 700 and 840 wells in terms of the cost of laying the oil and gas pipelines compared to ACO and GA. It should be noted that the ACO algorithm showed medium performance in terms of the cost of laying oil and gas pipelines compared to PSPA and GA.

Study on internal stress damage detection in long-distance oil and gas pipelines via weak magnetic method

Weak magnetic stress detection is an important issue in oil–gas pipeline internal detection area. In order to verify the characteristics of weak magnetic stress internal detection signals, we built herein a magneto-mechanics equivalent model having a balanced magnetic field. First, we calculated the relationship between the stress and the weak magnetic signals; consequently, the analysis propagation laws of the weak magnetic signals with non-magnetic saturation were pointed out. Finally, the theoretical model was validated by a systematic experimental research. The analytical results show that a one-to-one linear link between the weak magnetic signals and the stress concentration is clear. Instead, the change of the weak magnetic signals with the liftoff is nonlinear, therefore we are proposing the Boltzmann liftoff correction factor whose degree of adaptability of the equivalent model can reach the value of 94%. It is possible to note that when the liftoff is in the approximate linear stage, the relevance ratio and the recognition rate of the magneto-mechanics curve show a high-quality. This conclusion is important in the engineering field for the set of the liftoff.

Study on CA-CFAR Algorithm Based on Normalization Processing of Background Noise for HI of Optical Fiber

Optical fiber pre-warning system (OFPS) is often used to monitor the occurrence of disasters such as the leakage of oil and natural gas pipeline. It analyzes the collected vibration signals to judge whether there is any harmful intrusion (HI) events. At present, the research in this field is mainly focused on the constant false alarm rate (CFAR) methods and derivative algorithms to detect intrusion signals. However, the performance of CFAR is often limited to the actual collected signals distribution. It is found that the background noise usually obeys non-independent and identically distribution (Non-IID) through the statistical analysis of acquisition signals. In view of the actual signal distribution characteristics, this paper presents a CFAR detection method based on the normalization processing for background noise. A high-pass filter is designed for the actual Non-IID background noise data to obtain the characterization characteristic. Then, the background noise is converted to independent and identically distribution (IID) by using the data characteristic. Next, the collected data after normalization is processed with efficient cell average constant false alarm rate (CA-CFAR) method for detection. Finally, the results of experiments both show that the intrusion signals can be effectively detected, and the effectiveness of the algorithm is verified.

USE OF RENEWABLE SOURCES OF ENERGY FOR NUTRITION OF OWN REQUIREMENTS OF OIL PIPELINE

The development of the modern world directly depends on the development of transport infrastructure. One of the types of transportation is the pipeline system, they are designed mainly for the delivery of liquid from one region to another, the most popular pipelines are oil pipelines and gas pipelines. Water pipelines are usually located in densely populated areas, while oil pipelines are often located in hard-to-reach areas, for example, in the regions of the Far North. As a rule, such territories do not have a centralized power supply, which creates additional difficulties in ensuring their functioning. Generally, diesel generators are the source of electricity in such regions. Based on the analysis of the oil transportation cycle, the authors proposed a certain way to increase its energy efficiency and increase reliability. The aim of this work is increasing energy efficiency and reliability of electrical equipment for own needs in oil pipelines. To achieve this goal, it is proposed to replace diesel generators with plants using renewable energy sources. In particular, it is proposed to use wind-solar installations. These installations are supposed to be used as the main power sources, while diesel generators will be used as stand-by sources of energy. The article provides a feasibility study for this event, as well as specific technical solutions for its implementation. First of all, this event will reduce fuel costs. Also, this will increase the category of reliability of the emergency valve from the third to the first.

Sealing Performance and Optimization of a Subsea Pipeline Mechanical Connector

Researchers seldom study the optimum design of a mechanical connector for subsea oil-gas pipeline based upon the sealing performance. An optimal design method of a novel subsea pipeline mechanical connector is presented. By analyzing the static metal sealing mechanism, the critical condition of the sealing performance is established for this connector and the formulation method of the contact pressure on the sealing surface is created. By the method the minimum mean contact pressure of the 8.625 inch connector is calculated as 361 MPa, which is the constraint condition in the optimum design of connector. The finite element model is created in ANSYS Parametric Design Language (APDL) and the structure is optimized by the zero-order method, with variance of contact pressure as the objective function, and mean contact pressures and plastic strains as constraint variables. The optimization shows that variances of contact pressure on two sealing surfaces decrease by 72.41% and 89.33%, respectively, and mean contact pressures increase by 31.18% and 52.84%, respectively. The comparison of the optimal connectors and non-optimal connectors in the water pressure experiments and bending experiments shows that the sealing ability of optimized connectors is much higher than the rated pressure of 4.5 MPa, and the optimal connectors don’t leak under the bending moment of 52.2 kN·m. This research provides the formulation to solve contact pressure on the sealing surface and a structure optimization method to design the connectors with various dimensions.

Modeling of composite coupling technology for oil-gas pipeline section resource-saving repair

The article presents a variant of modeling and calculation of a main pipeline repair section with a composite coupling installation. This section is presented in a shape of a composite cylindrical shell. The aim of this work is mathematical modeling and study of main pipeline reconstruction section stress-strain state (SSS). There has been given a description of a structure deformation mathematical model. Based on physical relations of elasticity, integral characteristics of rigidity for each layer of a two-layer pipe section have been obtained. With the help of the systems of forces and moments which affect the layers differential equations for the first and second layer (pipeline and coupling) have been obtained. The study of the SSS has been conducted using the statements and hypotheses of the composite structures deformation theory with consideration of interlayer joint stresses. The relations to describe the work of the joint have been stated. Boundary conditions for each layer have been formulated. To describe the deformation of the composite coupling with consideration of the composite cylindrical shells theory a mathematical model in the form of a system of differential equations in displacements and boundary conditions has been obtained. Calculation of a two-layer cylindrical shell under the action of an axisymmetric load has been accomplished.

Electromagnetic ultrasonic guided wave long-term monitoring and data difference adaptive extraction method for buried oil-gas pipelines

An increasing number of buried oil-gas pipelines are generated in recent years and defects occur with higher probability in their long-running process. This work proposes an electromagnetic ultrasonic guided wave (EUGW) long-term monitoring scheme for buried oil-gas pipelines and a data difference adaptive extraction method for the monitoring data. The T (0,1) mode guided wave is selected because of its non-dispersive characteristic. For the electromagnetic acoustic transducer (EMAT), a circumferentially magnetized nickel strap is bonded on the pipe to provide the bias magnetic field and the excitation coils are winded on the nickel strap to provide the dynamic magnetic field. A detection stub is planted on the ground and the connector of buried coils is installed in the stub. The difference array is constructed and adaptive gain and attenuation are performed in the data difference adaptive extraction method. The EUGW long-term monitoring scheme is on-site applied for buried oil pipes in Jinan city, Shandong province, China. The EMAT is installed and buried with the pipe, and the periodical detection is conducted from December 2015 till now, once per month. A pit is found and verified by excavation at the distance 9.25 m from the buried EMAT on the flow direction. On-site detection results show that the data extraction method can dramatically improve the signal to noise ratio of the monitoring data and accurately extract the difference and variation of the pipe's structural health condition that occurred in the long-term service. The EUGW long-term monitoring scheme is proved to be a feasible method with prosperous prospect for the structural health monitoring of buried oil-gas pipelines.

Modeling and Simulation Study for Solid Particles Detection in Gas–Oil Pipelines Using Field Free Line in Magnetic Particle Imaging and Its Hardware Realization

This paper suggests a new magnetic particle imaging (MPI) technique for 2-D tomographic imaging to detect the presence of flowing solid particles (i.e., black powder, which consist of paramagnetic nanoparticles) passing through gas-oil pipelines. The hardware consists of a ring of a modified Halbach array of 24 permanent magnets, in addition to two surrounding Helmholtz coil pairs, and a receiving coil, which are evenly distributed across a cross section of the probe. With the application of static and dynamically moving drive fields, the MPI utilizes the full benefit of superparamagnetic iron oxide nanoparticles (SPIONs) by providing a linear response when they are exposed to a relatively low magnetic field and no response when they are saturated. The scanning of region of interest with the field-free line (FFL) instead of the field-free point (FFP) is motivated by the fact that a high-intensity dc current is required for FFP, which is not tolerated in oil-gas pipelines where the maximal current should not exceed few amperes. With the presence of an oscillatory magnetic field, SPIONs react with a nonlinear magnetization response, which is further measured by the receiving coil. A 2-D image reconstruction is then performed using the frequency-based image reconstruction process. The hardware design, specifically the sizing of permanent magnets with regard to their relative position and dimensions, was refined following an optimization technique based on the particle swarm optimization technique. The assessment of the system using finite-element method indicates that the system can reconstruct the 2-D profile of the SPION with a mean absolute error of prediction of less than 4% and 12% using FFL and FFP methods, respectively.

A focus on different factors affecting hydrogen induced cracking in oil and natural gas pipeline steel

In this research, hydrogen induced cracking (HIC) behavior of an API X70 pipeline steel has been studied. In order to create HIC cracks, an electrochemical hydrogen charging experiment was carried out on X70 steel by using 0.2 M sulfuric acid and 3 g/l ammonium thiocyanate for 8 h. Moreover, SEM, EDS and EBSD techniques were used to characterize the as-received (AR) steel and investigate the different aspects of HIC phenomenon as well. The results showed that the inclusions and precipitates which play a key role in HIC phenomenon have been distributed randomly through the cross-section of tested steel. However, the concentration of them was higher at the center of cross-section than other areas. All HIC cracks initiated and propagated through the center of thickness where center segregation of elements has occurred. It is also observed that HIC cracks were initiated from several special types of inclusions and precipitates such as manganese sulphide and carbonitride precipitates. EBSD results showed that the dominant local texture of center of thickness in RD-TD plane was {001}//ND and {111}//ND. Moreover, HIC cracks propagate through differently oriented grains where the local texture is random.

Turkey s Unique Energy Corridor Role at the Center of Eurasia in the 21st Century

This paper aims to examine Turkey’s sui generis energy role at the center of Eurasia in the 21st century. With the start of using oil and natural gas in the industry and also elsewhere, drilling, processing and transporting these resources have become an important issue between demanders and suppliers. In Eurasia, although eastern part of the continent is rich in terms of oil and gas, western part of the continent lacks significant volume of hydrocarbons. In terms of energy security perspective, both producers and demanders prioritize the uninterrupted transportation of hydrocarbons. This situation necessitates the presence of transit countries. Nowadays, the new world order has been shaping in the perspective of regional instabilities. In addition, center of gravity of the continent has been changing. Turkey is at the center of these developments and continent as an energy corridor. Hence, the existing and projected oil and natural gas pipeline projects will be beneficial for either Turkey or energy supplier/demander countries.

The Potential Threat of China-Myanmar Gas Pipeline

China needs energy to sustain its economic growth. However the amount of energy resources in China are insufficient while the energy consumption grows rapidly. Recently, China is the second largest energy consumer. In order to achieve energy security and reduce carbon emissions to save environment, China is actively increasing the consumption of natural gas. China imports natural gas from overseas such as from Middle East, Kazakhstan, Turkmenistan and others. About half of China’s energy resources import from foreign sources. However, Import natural gas from these countries come with risks. The instability of politic in those areas influences the natural gas price, insecurity of travelling the natural gas via sea can reduce the amount natural gas come to China, and so on. China then looks alternative countries that closer to China to supply and secure its energy demand. In doing so, in 2008 China signed agreement with Myanmar to build oil gas pipeline. The gas pipelines have operated in July 2013. However, China-Myanmar gas pipelines project do not come without risk. This paper examines potential risks of China-Myanmar gas pipelines. This paper argues there are security, environmental, and cyber, and other issues that can be potential threat to China Myanmar gas pipeline project

The axial crack testing model for long distance oil-gas pipeline based on magnetic flux leakage internal inspection method

Abstract Traditional pipeline magnetic flux leakage (MFL) internal technology mainly uses axial excitation method, which could not recognize the narrow crack defects in the axial direction of the pipe. In this paper, by using a linear magnetic dipole model to study the circumferential excitation method, the detection model of axial crack in pipeline is established, and the relationship between MFL signals and the geometry characteristics of axial cracks is calculated. Finally, the detection accuracy and identification method of axial cracks is analyzed. Research results show that: non-uniform magnetic field generated by circumferential excitation can effectively detect the narrow cracks in the axial direction of the pipeline and distinguish the depth and the width characteristics of cracks. However, the background magnetic fields near the magnetic poles have great influence on the detection accuracy, and the smooth interpolation method of the cubic-spline interpolation can be used to reduce the influence effectively.

Study on the Time-Dependent Evolution of Pitting Corrosion in Flowing Environment

Pitting corrosion is one of the most destructive forms of localized corrosion in oil-gas pipelines. Due to being obscured by corrosion products and little loss of material with small effect on the surface, this kind of corrosion is extremely insidious. In this work, a novel multi-physics model is proposed to investigate the growth behavior of pitting corrosion in the presence of fluid flow. Various physical and chemical phenomena are taken into account in a coupled scheme, including chemical reactions, electrochemical reactions, flow disturbance and the mass transport of species. The mass transport is attributed to diffusion, electro-migration and convection. The time-dependent evolution of the pit morphology is implemented via an arbitrary Lagrangian-Eulerian method. The mechanism of the pitting corrosion is revealed with the integration of flow field, local chemical environment and the electrochemical behavior within the pit hole. Special emphasis is put on the relationship between the flowing fluid and the corrosion behavior. The results show that the flowing fluid would result in an asymmetric distribution of the species concentration and corrosion current density within the pit hole. It is found that the pit growth dynamics is determined by the combined effect of solution chemistry and electrical field. It is also indicated that the pH in the bulk solution and the flow rate have a significant coupling influence on the pitting corrosion behavior.

Mechanical Response of a Buried Pipeline to Explosion Loading

In order to study the stress-strain response of a buried pipeline with internal pressure under the ground explosive, a numerical calculation model of the buried pipeline with internal pressure was established. The dynamic process of the buried pipeline was simulated after the explosion on the ground. Effects of internal pressure, magnitude of TNT, wall thickness, and buried depth on the stress-strain of pipeline were studied. The results showed that the region of high stress and plastic strain presented to the upper pipeline and extended toward axial direction, and then extended toward circumferential direction under the ground explosion. With the increasing of internal pressure, the high-stress zone fades away, the plastic strain zone and deformation of pipeline decrease. The stress and deformation of buried pipeline increase with the magnitude of TNT increases, but they decrease with the increasing of buried depth and wall thickness. Those results can provide theoretical basis and reference for pipe laying of oil-gas pipeline, safety evaluation, and maintenance, etc.

ENERGY DIPLOMACY OF TURKEY

The article deals with current issues of energy diplomacy of Turkey. The authors describe the main positive and negative results of Turkey's foreign energy policy in terms of the implementation of major energy projects. Geopolitical processes in the world, the conflict of interests of various countries in the political arena are important factors that affect the crude oil and natural gas pipeline projects. Particular attention is paid to the problems and prospects of cooperation between the Turkish Republic and the Russian Federation in the fuel and energy complex. The authors describe the interaction betweeen Russia and Turkey in the energy sector, including geo-economic interests of the countries in the Russian-Turkish gas dialogue. Turkey made efforts to position as an alternative gas supply route, taking advantage of concern about increasing Europe's dependence on Russian exports. Last years Turkey has set itself the important task - to turn from transit country into a regional gas hub. Ukrainian crisis increased the geostrategic importance of the Black Sea region to Russia, as well as strengthened the ambition of the Turkish side. The authors also highlight the prospects of the natural gas pipeline project from Russia via the Black Sea to Turkey and to the Turkish-Greek border, which named "Turkish stream". This project was frozen in terms of military and political processes at the end of 2015 in Syria.

Multi-temporal assessment of ground cover restoration and soil erosion risks along petroleum and gas pipelines in Azerbaijan using GIS and remote sensing

The main goal of this research was to perform vegetation cover restoration and soil erosion risk assessment based on multi-temporal NDVI monitoring and deterministic USLE erosion prediction model along Baku–Tbilisi–Ceyhan Oil and South Caucasus Gas pipelines. The categorization of NDVI derived from IKONOS 2007 and PLEIADES 2012 high-resolution multispectral satellite images into the bare lands, sparse and dense vegetation revealed the positive vegetation cover restoration along oil and gas pipelines. The change detection analysis of NDVIs showed that the class of ‘Significant Increase in Vegetation’ was 5.40 km2 within the croplands. However, the classes of ‘Significant Decrease in Vegetation’ and ‘No Significant Change in Vegetation’ were observed to be 2.56 and 5.10 km2 within croplands, correspondingly. This decrease can be explained by the encumbrances applied for the partial restrictions of land-use activities along oil and gas pipelines to mitigate potential risks to pipelines and by the slow natural vegetation restoration. NDVI analysis for 50-m section polygons of pipeline corridor and contiguous areas showed that 7072 polygons had no significant NDVI difference in 2012, whereas in 2007 it was 4383. USLE model run with cover-management factor derived from PLEIADES NDVI 2012 showed higher number of polygons with predicted erosion class of ‘0–10 ton/ha’ which is acceptable and not critical to pipelines. For higher erosion classes more than ‘0–10 ton/ha’, USLE model run with IKONOS NDVI 2007 revealed higher number of polygons. USLE model run predicted 37 % of total number of erosion occurrences identified during 2005–2014.

Large-scale field trial to explore landslide and pipeline interaction

Oil–gas pipelines for natural gas transmission from West to East China will inevitably undergo landslide especially in Southwestern China. Studies on the interaction between landslides and pipelines, particularly on the stress and deformation laws for pipelines under the action of landslides, are of great importance. A large-scale landslide model with a prototype gas pipeline subjected to the same internal pressure as in operation, was constructed outdoors to test and monitor the stress and strain in the pipeline together with landslide deformation. It is concluded that the pipeline stresses change in close relation with the displacement of the landslide. The relationship can be described with an exponential function. The induced stress distribution and deformation along the pipeline is in the form of a saddle. The most critical stresses on the pipeline are concentrated on both sides of the landslide border and in the central part of the landslide. These results are helpful to provide technical support for numerical simulations and for pipeline design, construction and remediation.

Numerical simulation of buckling behavior of the buried steel pipeline under reverse fault displacement

Abstract. Reverse fault movement is one of the threats for the structural integrity of buried oil-gas pipelines caused by earthquakes. Buckling behavior of the buried pipeline was investigated by finite element method. Effects of fault displacement, internal pressure, diameter-thick ratio, buried depth and friction coefficient on buckling behavior of the buried steel pipeline were discussed. The results show that internal pressure is the most important factor that affecting the pipeline buckling pattern. Buckling mode of non-pressure pipeline is collapse under reverse fault. Wrinkles appear on buried pressure pipeline when the internal pressure is more than 0.4 Pmax. Four buckling locations appear on the buried pressure pipeline under bigger fault displacement. There is only one wrinkle on the three locations of the pipeline in the rising formation, but more wrinkles on the fourth location. Number of the wrinkle ridges and length of the wavy buckling increase with the increasing of friction coefficient. Number of buckling location decreases gradually with the decreasing of diameter-thick ratio. A protective device of buried pipeline was designed for preventing pipeline damage crossing fault area for its simple structure and convenient installation. Those results can be used to safety evaluation, maintenance and protection of buried pipelines crossing fault area.

Weak magnetic flux leakage: A possible method for studying pipeline defects located either inside or outside the structures

Magnetic leakage distribution results from linear defects of oil–gas pipelines in a weak magnetic field, which is modeled by the magnetic dipole theory. The analysis is useful for the identification of defects located either inside or outside the pipelines. The results indicate that the radial signals of inside–outside defects can be clearly distinguished, and the axial signals are basically the same in a weak magnetic field. The theoretical and the experimental results are very consistent.

A new leak location method based on leakage acoustic waves for oil and gas pipelines

In order to study a new leak detection and location method for oil and natural gas pipelines based on acoustic waves, the propagation model is established and modified. Firstly, the propagation law in theory is obtained by analyzing the damping impact factors which cause the attenuation. Then, the dominant-energy frequency bands of leakage acoustic waves are obtained through experiments by wavelet transform analysis. Thirdly, the actual propagation model is modified by the correction factor based on the dominant-energy frequency bands. Then a new leak detection and location method is proposed based on the propagation law which is validated by the experiments for oil pipelines. Finally, the conclusions and the method are applied to the gas pipelines in experiments. The results indicate: the modified propagation model can be established by the experimental method; the new leak location method is effective and can be applied to both oil and gas pipelines and it has advantages over the traditional location method based on the velocity and the time difference. Conclusions can be drawn that the new leak detection and location method can effectively and accurately detect and locate the leakages in oil and natural gas pipelines.