Gas Pipeline Transportation Research Articles

Перспективы газогидратных технологий на рынке морских перевозок природного газа

The article considers the modern problems and prospects of the development of technologies of transporting the natural gas by sea due to the fact that gas hydrate deposits are found on the bottom of Lake Baikal, the Black Sea, the Caspian Sea and the Okhotsk Sea. It has been stated that despite the proved gas hydrate deposits the fields have not been explored yet. Introducing the technology for transporting gas by sea in gas hydrate form is being substantiated. Comparative analysis of LNG, CNG and NGH technologies for sea transportation of natural gas proved that the transport component of the NGH technological chain has significant advantages over LNG and CNG technologies. The process of converting thermal energy of the ocean has been proposed to use for increasing the energy efficiency of methane production from subsea gas hydrate deposits in the gas hydrate cycle, which can save 10-15% of the produced methane for electricity generation. A schematic and technological solution of a gas production complex is presented, according to which carbon dioxide is introduced into the gas hydrate layer to extract methane from gas hydrates. To improve the kinetics of replacing methane with carbon dioxide in gas hydrates it is proposed to recycle a portion of CO2. Due to the specific and diversified geographic, economic, political and other conditions the conventional technologies for pipeline transportation of gas and LNG cannot fully meet the requirements of gas export and production projects. It has been inferred that NGH technology is most suitable for solving the problem of diversifying natural gas supplies from the Arctic regions, the Black Sea and in the development of offshore gas and oil fields.

Molecular mechanism for methane hydrate nucleation on corroded iron surface

Gas hydrate plugging in oil and gas transportation pipelines is a knotty problem for flow assurance practices. The nucleation mechanism of methane hydrate on corroded iron pipeline surface is still unclear. In this work, both smooth and corroded iron particles were packed into a hydrate reactor to investigate the relationship between the induction time of methane hydrate and the liquid–metal contact area. Experimental results indicated an insignificant difference among the particles of varied specific surface areas when submerged in the aqueous phase. However, the induction time was reduced by more than 60% when the particles were located above the gas–liquid interface and further shortened by 80% if the particles were corroded. Molecular dynamics simulations indicated that decreased interlayer spacing between the iron layers would facilitate methane hydrate formation in the initial period. Based on our energy analysis, this was ascribed to an increased curvature of the gas–liquid interface, causing a decrease of energy barrier by 54% for a methane molecule to transfer from the interface into the bulk liquid and subsequently, an increase of methane concentration in solution. Meanwhile, two layers of water molecules were observed to adsorb on the iron surface stably and no hydrate cages formed in such region throughout the simulation time. The microscopic phenomenon agreed well with the experimental results, which highlighted the influence of the gas–liquid–metal three-phase interface other than the liquid–metal contact area upon methane hydrate nucleation. The results shed new insights on predicting the prioritized locations of methane hydrate formation in metallic pipelines to reduce the potential hydrate plugging risk.

Investigation on Erosion of Continuous Bending Pipes in Different Directions

With the increasing demand for natural gas in the world, ensuring the safety and stability of pipeline transportation of natural gas has become an important subject. Compared with the studies focused on the erosion of single bend, T-pipe, and U-pipe, the studies on the continuous bend in different directions are scarce. In this paper, the model is characterized by three straight pipes with the same length and directions along the Z, Y, and X axes of the Cartesian coordinate system. The numerical simulation of gas-solid two-phase flow under different gas to solid mass ratios in the continuous bent pipeline is carried out by selecting the Oka erosion model. The results indicate that the velocity distribution of the second bend is different from that of the first bend. With the change of flow deflection angle and the accumulation of the centrifugal force, the shape of the velocity contours in the second bend turns from “basin” into a comma and the velocity experiences a process including rapid increase, slow decrease, gradual increase, and steep decrease. When the flow rate is 12.5 m/s, the maximum speed of the second bend is about 5 % greater than that of the first bend. Instead of a “straight-line” shape in the erosion area of the first bend, the second presents a feather shape. As the flow rate increases gradually, the shape characteristics of the feather erosion zone change from short and dense to long and loose. Besides, the maximum erosion rate of the second bend is greater than that of the first even about 1.52 times. Finally, according to the simulation results, the protection suggestion of the continuous elbow is given.

The effect of volatile organic acids and CO2 on the corrosion rate of carbon steel from a Top-of-Line-Corrosion (TLC) perspective

Models for predicting top-of-line corrosion (TLC) rates on carbon steels are important tools for cost-effectively designing and operating natural gas transportation pipelines. The work presented in this paper is aimed to investigate how the corrosion rates on carbon steel is affected by acids typically present in the transported pipeline fluids. This investigation may contribute to the development of improved models. In a series of experiments, the corrosion rate differences for pure CO2 (carbonic acid) corrosion and pure organic acid corrosion (acetic acid and formic acid) on X65 carbon steel were investigated at starting pH values; 4.5, 5.3, or 6.3. The experiments were conducted in deaerated low-salinity aqueous solutions at atmospheric pressure and temperature of 65 °C. The corrosion rates were evaluated from linear polarization resistance data as well as mass loss and released iron concentration. A correlation between lower pH values and increased corrosion rates was found for the organic acid experiments. However, the pH was not the most critical factor for the rates of carbon steel corrosion in these experiments. The experimental results showed that the type of acid species involved and the concentration of the undissociated acid in the solution influenced the corrosion rates considerably.

Impacts of structural parameters of baffle plate on jetting pigging robot in the underwater oil and gas pipeline

During the operation of oil and gas transportation pipeline, condensate forms on the inner wall of the pipeline can lead to reduced transportation efficiency and potential safety hazards. Pigging is a widely used technology to remove deposition in pipelines. From the studies, it is found that the effect of pigging largely depends on the structure of the pig. The jetting pig is a new type of pigging device designed to prevent the blocking in the pigging process, and its baffles play an important role in guiding the jet fluid. In this paper, the impact of the structure of the baffle plate on the downstream flow field of the jetting pig is simulated and analyzed. The surface of the baffle plate is changed by using the curve of the contraction section of the water tunnel. It is found that the baffle plate structure has a great influence on the flow field at the outlet of the jet pig: (1) The increase of buffle area leads to the increase of turbulent kinetic energy and the decrease of velocity; (2) The rise of edge angle lead to the regular change of turbulent kinetic energy; (3) Different curved surfaces make the change of turbulent kinetic energy and velocity. The results in this study are helpful for a better understanding of mechanism of jetting pig and improved design of mechanical structure for improved pigging performance.

Automation and Automatic Control Technology of Natural Gas Pipeline Transportation

Automation and Automatic Control Technology of Natural Gas Pipeline Transportation

An integrated framework for criticality evaluation of oil & gas pipelines based on fuzzy logic inference and machine learning

Oil & gas transportation pipeline is susceptible to failure because of the influence of external complex environment and internal aggressive medium. It is necessary to accurately evaluate the failure criticality of the pipeline for developing reasonable protective measures. However, due to the complexity and uncertainty of the failure scenarios of the oil & gas pipeline, direct quantitative evaluation of the failure criticality is very difficult. Therefore, this paper proposed a novel evaluation framework based on an integration of fuzzy logic inference and machine learning approaches. In this framework, transportation interruption effect, safety/health effect, environment/ecological effect, and equipment maintenance effect are set as the influencing factors on failure criticality of pipelines. Fuzzy logic inference was applied to generate the mapping relationship of the influencing factors to criticality index and establish the prediction model for criticality index evaluation of oil & gas pipelines. For facilitating the evaluation process, three machine learning approaches (i.e., multilayer perceptron, support vector regression and random forest) were employed to fit the relationship so as to construct an additional, easy-to-use prediction model. Furthermore, the sensitivity of each influencing factor was discussed by Sobol method. The results show that the random forest model has better prediction capability in comparison of the other two models, and safety/health effect and environment/ecological effect have the biggest impact on criticality. Finally, an application example of natural gas pipeline was conducted by using the proposed framework, which verified its practicability and flexibility.

Detecting Pipeline Pathways in Landsat 5 Satellite Images with Deep Learning

Energy system modeling is essential in analyzing present and future system configurations motivated by the energy transition. Energy models need various input data sets at different scales, including detailed information about energy generation and transport infrastructure. However, accessing such data sets is not straightforward and often restricted, especially for energy infrastructure data. We present a detection model for the automatic recognition of pipeline pathways using a Convolutional Neural Network (CNN) to address this lack of energy infrastructure data sets. The model was trained with historical low-resolution satellite images of the construction phase of British gas transport pipelines, made with the Landsat 5 Thematic Mapper instrument. The satellite images have been automatically labeled with the help of high-resolution pipeline route data provided by the respective Transmission System Operator (TSO). We have used data augmentation on the training data and trained our model with four different initial learning rates. The models trained with the different learning rates have been validated with 5-fold cross-validation using the Intersection over Union (IoU) metric. We show that our model can reliably identify pipeline pathways despite the comparably low resolution of the used satellite images. Further, we have successfully tested the model’s capability in other geographic regions by deploying satellite images of the NEL pipeline in Northern Germany.

Corrosion mechanism and anticorrosion technology of oil and gas gathering and transportation pipeline

In the process of oilfield exploitation, the composition of crude oil is relatively complex, which may have strong corrosive medium, and the oil field gathering and transportation pipeline is distributed in various areas of the oilfield, which plays an important role. The corrosive medium of crude oil has a certain corrosive effect on the oil field gathering and transportation pipeline, and once the corrosion is serious, it will cause the leakage of the gathering and transportation pipeline. China’s oilfields have experienced many years of continuous development, some oilfields have entered the middle and late stage of exploitation, and have made certain achievements in various stages of exploitation. We have conducted in-depth research and Analysis on the corrosion factors of oil gathering and transportation pipeline, which consumes a lot of manpower, material resources and financial resources. Therefore, we need to analyze and study the factors influencing the corrosion of oil gathering and transportation pipeline, formulate effective anti-corrosion measures according to the actual situation, extend the service life of oil gathering and transportation pipeline, and promote the longterm development of oil field exploitation and operation.

Analysis of the optimal spatial distribution of natural gas under ‘transition from coal to gas’ in China

China has been attempting to realise green sustainable economic development. Thus, China has proposed and begun to implement the ‘switching from coal to gas’ policy to realise the energy structure transition but neglected to consider seasonal natural gas demand fluctuations, gas supply shortages, the backward gas transportation and storage infrastructure. This paper constructs a model of China’s natural gas distribution system by incorporating these four factors: ① supply factors including domestic natural gas fields, liquid natural gas receiving stations, internationally piped gas sources, ② demand factors including domestic regional demands, ③ real natural gas transportation pipeline systems in the country, and ④ the pricing mechanism of natural gas. Optimal spatial natural gas distribution with maximum social welfare under the three conditions are simulated, respectively: the ① fixed price system, ② market pricing mechanism, and ③ seasonal fluctuations. The simulation results indicate substantial changes would occur in China’s natural gas system during the switch from coal to gas, and the natural gas infrastructure requires further improvement. This paper also provides references for the natural gas storage facility location selection in China.

Analysis of the corrosion failure causes of shale gas surface pipelines

AbstractA shale gas gathering and transportation pipeline in a good block in Sichuan Province started leaking after less than a year of operation. To investigate the causes of corrosion of the sulfate‐reducing bacteria (SRB), optical microscopy, scanning electron microscopy, and X‐ray diffraction were used to analyze the corrosion and perforation of the shale gas surface pipeline in conjunction with bacterial corrosion simulation experiments. The results showed that the pipeline material (L360N) conformed to the requirements of the American Petroleum Institute 5 L standard and that extracellular polymeric substances were present in the corrosion pits. The corrosion products mainly included FeCO3, FeS, CaCO3, MgCO3, and Fe mineralization. At 40°C, the uniform corrosion rate of L360N in the simulation experiment was 0.234 mm/a, and the local corrosion rate was 0.458 mm/a. SRB, saprophytes, and iron bacteria were detected in the on‐site water medium and corrosion products, indicating that the main causes of shale gas pipeline corrosion are bacterial and CO2 corrosion.

The Flow Pattern Transition and Water Holdup of Gas–Liquid Flow in the Horizontal and Vertical Sections of a Continuous Transportation Pipe

A series of experiments were conducted to investigate the flow pattern transitions and water holdup during oil–water–gas three-phase flow considering both a horizontal section and a vertical section of a transportation pipe simultaneously. The flowing media were white mineral oil, distilled water, and air. Dimensionless numbers controlling the multiphase flow were deduced to understand the scaling law of the flow process. The oil–water–gas three-phase flow was simplified as the two-phase flow of a gas and liquid mixture. Based on the experimental data, flow pattern maps were constructed in terms of the Reynolds number and the ratio of the superficial velocity of the gas to that of the liquid mixture for different Froude numbers. The original contributions of this work are that the relationship between the transient water holdup and the changes of the flow patterns in a transportation pipe with horizontal and vertical sections is established, providing a basis for judging the flow patterns in pipes in engineering practice. A dimensionless power-law correlation for the water holdup in the vertical section is presented based on the experimental data. The correlation can provide theoretical support for the design of oil and gas transport pipelines in industrial applications.

Study on corrosion mechanism and the risk of the shale gas gathering pipelines

Corrosion and perforation accidents often occur in shale gas gathering and transportation pipelines, which causes serious economic losses. The medium in shale gas gathering pipelines is complex, and the corrosion rate is fast under the combined action of many factors. In this paper, the corrosion mechanism of shale gas gathering and transportation pipelines was studied by field data analysis and experiments. By means of multiphase flow simulation analysis and magnetic flux leakage internal detection, the characteristics and distribution of pipeline corrosion defects were identified, and the corrosion sensitive area was further determined. The results show that in the shale gas gathering pipelines, there were multiple corrosive media of CO2, O2 and SRB. The local corrosion was more serious under the promotion of Cl- and low liquid flow rate. The 3–9o'clock position on the low-lying and uphill section of the pipelines were the corrosion sensitive areas. Through the analysis of internal corrosion mechanism and ERF curves, there were many high-risk corrosion areas in the pipelines.

Pipe-soil vibration characteristics of natural gas pipelines during the pigging process

During the pigging process in long-distance natural gas transportation pipelines, the pig is easy to block and cannot be located accurately, resulting in serious economic losses. The analysis of pipe and soil vibration rule can be used as the basis for pig positioning. How to locate accurately the pig has become an urgent problem. In this study the coupled pipe-soil vibration model under the pigging action is proposed, and a three-dimensional symmetric pipe-soil vibration finite element model is established through ABAQUS. The influence of the pig running velocity and the friction coefficient of the inner surface on the vibration of the pipeline, as well as the influence of the propagation direction and the soil elastic modulus on the vibration propagation of the soil are studied. The research results show that the displacement amplitude of pipeline vibration increases with the increase of the running velocity of the pig, and at 0.8 m/s, the displacement reaches a peak of 27 μm. At the same time, the amplitude of pipe displacement increases as the friction coefficient between the pig and the pipeline increases. In the soil different directions, it is concluded that at 200 mm, the maximum displacement amplitude in the 45° direction can reach 15 μm. For the soil elastic modulus, when the propagation distance is 200 mm in soil with an elastic modulus of 10 MPa, the vibration velocity is significantly higher than that in other soils, and the maximum can reach 70 μm/s. Under the same conditions, the elastic modulus in the soil with an elastic modulus of 50 MPa, the maximum vibration velocity is 27 μm/s, indicating that the elastic modulus of the soil has a greater influence on the vibration velocity.

Study on the Segmental Pigging Process for the Wet Gas Gathering and Transportation Pipelines of the Puguang Gas Field

Abstract The gathering and transportation pipeline known as Line 1 of Puguang Gas Field has the characteristics of wet gathering and transportation containing high sulfur content, large drops, and liquid loading in low-lying areas. In the process of one pigging operation on the site, the surge volume provided by the no. 1 separator in the master gas gathering station was not effectively utilized and the time intervals for the neighboring pipeline sections were too long. In this paper, we designed several pigging proposals. OLGA was applied to analyze the operating parameter changes for the gathering and transportation pipeline Line 1, which finally determined a reasonable pigging sequence. We designed and selected the “optimal pigging proposal”, which the time duration for the pigging operation of the seven pipeline sections was decreased to 16.91 h. Guided by the “optimal pigging proposal”, the downstream pipeline sections will be challenged by the risks of ice blockage. The ground eddy device was improved in the article, for the purpose of draining liquid loadings in low-lying areas in the Puguang Gas Field and controlling the slug flow. In addition, the application effects of the device were analyzed.

Evaluation the effect of the ambient temperature on the liquid petroleum gas transportation pipeline

Abstract Liquefied petroleum gas (LPG) plays a major role in worldwide energy consumption as a clean source of energy with low greenhouse gases emission. LPG transportation is exhibited through networks of pipelines, maritime, and tracks. LPG transmission using pipeline is environmentally friendly owing to the low greenhouse gases emission and low energy requirements. This work is a comprehensive evaluation of transportation petroleum gas in liquid state and compressible liquid state concerning LPG density, temperature and pressure, flow velocity, and pump energy consumption under the impact of different ambient temperatures. Inevitably, the pipeline surface exchanges heat between LPG and surrounding soil owing to the temperature difference and change in elevation. To prevent phase change, it is important to pay attention for several parameters such as ambient temperature, thermal conductivity of pipeline materials, soil type, and change in elevation for safe, reliable, and economic transportation. Transporting LPG at high pressure requests smaller pipeline size and consumes less energy for pumps due to its higher density. Also, LPG transportation under moderate or low pressure is more likely exposed to phase change, thus more thermal insulation and pressure boosting stations required to maintain the phase envelope. The models developed in this work aim to advance the existing knowledge and serve as a guide for efficient design by underling the importance of the mentioned parameters.

Simulation Research on Acoustic Detection Technology of Buried PE Pipes

Polyethylene (PE) pipe has been widely used in gas transportation pipeline system because it overcomes the shortcomings of non-corrosion resistance of metal pipelines. However, the stiffness and strength of PE pipe are small, and it is easy to be destroyed in the third-party construction process. Moreover, PE pipe is not electrically or magnetically conductive, and it is unable to use the developed metal pipe detection method, which has brought great security risks. Urban gas pipeline accidents occur frequently, and the situation during the production is complex and severe. Therefore, it is of great significance to study how to effectively realize the detection of underground PE pipe. This paper verifies the feasibility of the acoustic method from the perspective of simulation. Firstly, it studies the influence of buried pipe depth on the received signal of geophone. Secondly, it studies the influence of buried pipe size on the received signal of PE geophone with a certain depth Finally, it studies the received signal of geophone when PE pipe is in mixed soil. The simulation results show that the method based on acoustic wave is suitable, the signal source emits a sweeping frequency single tone sine wave, which propagates to the target and is reflected. A string of geophones on the ground measure the velocity of the surface vibration. Given the propagation rate of wave in the material, time delay can be used between signal sent and received on the ground to obtain the estimated distance to the target.

A data-driven pipeline pressure procedure for remote monitoring of centrifugal pumps

Pumping systems are a key component of oil and gas pipeline transportation assets: monitoring their integrity is a crucial operation from a safety and revenue point of view. The solutions currently employed in the industry apply supervised machine learning techniques to data collected by multi-domain sensors directly installed on several positions of the pump itself; however, such approaches are not applicable on older machines, in contexts where a direct access to the pump is not possible, or whenever labelled data are not at disposal. This paper, instead, presents a predictive maintenance strategy where the condition of a centrifugal pump is tracked by solely exploiting standard pressure measurements, recorded also on remote points along the pipeline, and using an unsupervised learning approach. The smart monitoring strategy is presented and validated on historical pressure signals collected by Eni for several years on a crude oil transportation pipeline, located in Italy. Pressure data, recorded along the fluid line, are used to compute several statistical indicators on appropriate window lengths. These indicators are then fed to an unsupervised clustering procedure, based on a Gaussian mixture model. The output is an index within four different pump operational regimes, and a clustering visualization that permits the interpretation of the automatic regime classification. In fact, the manual inspection of the clusters shows that three of them describe standard modes (regular pumping operation, pumps off, flow regulations). The fourth one corresponds to high amplitude peaks in the signals and indicators, and so it is tagged as “anomalous” mode: pump maintenance logs reveal that the peaks are associated to damaged roller bearing movements, which disappear after the activation of the pump backup system. Anomalies are reported several days before the pump switch, so that a preventive maintenance could have been triggered. The robustness of the clustering algorithm is assessed on a statistical basis, whereas the overall validity of the monitoring system is tested on an instantaneous basis by applying the proposed model on two independent datasets, collected on real transportation pipelines: the results demonstrate the reliability of the proposed monitoring strategy in predicting and detecting all the pump failure events reported by the available maintenance logs. With respect to the mostly employed approaches, our machine learning procedure does not require any previous supervision of the data. Moreover, input data are the pressure transients produced by the pumps and guided within the fluid in the pipeline for long distances: pump failure analysis can be run using sensors located at several kilometers of distance from the pump itself, making a remote control strategy feasible.

Safe, Secure and Sustainable Oil and Gas Drilling, Exploitation and Pipeline Transport Offshore

The Special Issue “Safe, Secure and Sustainable Oil and Gas Drilling, Exploitation and Pipeline Transport Offshore” was focused on regulations, including technical and operational standards, safety technologies, and organizational factors, which can greatly contribute to the occurrence of accidents in the offshore oil and gas sector [...]

The U.S. Gas Pipeline Transportation Market: An Introductory Guide with Research Questions for the Energy Transition

Natural gas currently represents close to a third of U.S. primary energy consumption and has often been described as a bridge fuel in the context of the ongoing energy transition. As coal plants are retired and the share of variable renewable resources in the U.S. power markets grows, power sector CO2 emissions are declining and gas-fired power plants increasingly relied upon to provide peak and balancing services to complement the variable electricity supply from wind and solar plants. Growth in gas-fired electricity generation in the past decade has made the power sector the largest user of the U.S. interstate gas pipeline network, just ahead of the industrial and building sectors. Nevertheless, future gas demand from these latter two sectors, and from the power sector, is expected to be reduced by policy and regulatory initiatives aimed at electrification of heating loads and economy-wide decarbonization. These developments open up important questions around the role of the U.S. interstate pipeline network in the ongoing energy transition. Such questions include what changes may be needed in the gas transportation markets to provide more flexible gas delivery services to gas-fired generators that provide valuable balancing in the power markets, and how long-term stranded asset risk for gas transportation infrastructure should be managed in the face of electrification and decarbonization. The objective of this paper is to facilitate further research to address these types of questions by outlining the main market features and regulations important for understanding the U.S. gas transportation market.