Gas Pipeline Transportation Research Articles

Study on the influence of ignition position on the explosion characteristics of methane-air premix in a semi-closed pipeline

Flammable gas explosion frequently occurs in the actual oil and gas pipeline transportation or mining operations. Given this problem, this paper studies the effect of ignition positions on the explosion characteristics of the methane-air mixture using a semi-closed transparent gas explosion pipe. According to the results, regardless of ignition position, the overpressure curve of each measuring point presents a process of rising-falling to negative-rising-stabilizing, and the flame propagation to the open end (left flame) evolves from spherical to finger shape. As the ignition position is farther away from the closed end, the overpressure at the closed end and the average flame speed on the right side of the ignition source climb gradually. In contrast, the average flame speed on the left side declines gradually. Besides, When the ignition position（IP3 and IP4）are near the open end, P1（Overpressure at the closed end）overpressure curves under both working conditions oscillate obviously before reaching the peak. The flame front undergoes a repeated compression-stretch-recompression, and the extreme point of the oscillation overpressure waveform always corresponds to the extreme point of the flame position. During this period, the amplitude of the P1 curve grows linearly and parabolically with time. According to the research, the overpressure oscillation is triggered by the reverse pressure wave after the left-side flame rushes out of the pipeline under such working conditions. The growing amplitude during the oscillation can be caused by various factors, including the thermoacoustic instability and the interaction between the flame front of the closed end and the unburned gas column. The research results deepen the understanding of the combustion and explosion characteristics of flammable gas, better the explosion safety protection in its storage, transportation, and processing, and provide a theoretical basis for the safety protection of detonation devices.

Experiment and numerical simulation of distribution law of water-based corrosion inhibitor in natural gas gathering and transportation pipeline

The transmission medium of natural gas gathering and transportation pipelines usually contains corrosive gases, which will cause serious corrosion on the inner wall of the pipelines when they coexist with water. Therefore, it is necessary to add corrosion inhibitor to form a protective film to protect the pipeline. The distribution of corrosion inhibitors in a gathering and transportation pipeline in Moxi gas field was studied by combining experiment and simulation. The Pearson function was used to calculate the experimental and simulation results, and the correlation was more than 80%, indicating a high degree of agreement. The simulation results show that: ① The larger the pipe angle, filling speed and gas flow rate, the smaller the particle size, the better the distribution of corrosion inhibitor particles in the pipe. The filling amount will affect the concentration, but the distribution trend is unchanged; ② A method to determine the filling mode based on the loss was proposed, and for this pipeline, the loss of corrosion inhibitor was determined to be 5.31 × 10−3 kg/s, and the filling amount was recommended to be adjusted to 20 L/h, which has certain guiding significance for the actual filling strategy of pipeline corrosion inhibitor.

Kinetics of Methane Hydrate Inhibition in MgBr2, CaBr2, and ZnBr2 Solutions

Hydrate inhibition in the presence of high-density completion fluids such as bromide salts relevant in completion and workover operations and natural gas transportation pipelines is less studied in the literature. In this work, an experimental investigation has been carried out to study the kinetics of methane hydrate formation and dissociation in the presence of MgBr2, CaBr2, and ZnBr2 solutions at 1, 3, 5, 10, and 15 wt % concentrations to understand the effect of these salts on hydrate inhibition compared to pure water. The presence of salts decreases the moles of methane consumed, and the consumption decreases with an increase in the salt concentration. A stronger hydrate inhibition is observed in the presence of MgBr2 solution than in CaBr2 and ZnBr2. The hydrate formation rate decreased with the passage of time, but the rate was higher later if there were two induction points, such as in the case of 3, 5, and 10 wt % solutions of MgBr2 and 5 wt % solutions of CaBr2. The water-to-hydrate conversion (W–H) and the gas-to-hydrate conversion (G–H) decrease with an increase in concentration of the salt. The maximum reduction in W–H and G–H conversions observed is ∼55% when MgBr2 is present in 15 wt % concentrations compared to pure water. The number of moles of methane recovered during hydrate dissociation is maximum in the case of pure water, followed by ZnBr2 solutions, while for CaBr2 and MgBr2 solutions, it is almost the same when these salts are in 15 wt % concentrations. The hydrate dissociation rate is the highest in the case of pure water, but there are intervals of time when the dissociation rate in the MgBr2 and CaBr2 solutions observed is higher than that in pure water.

Failure analysis of biocomposite sandwich pipe under internal pressure – Application for high pressure gas transportation pipelines MEDGAZ

In this paper, analytical and 3D numerical models are developed to investigate the mechanical behavior of sandwich pipe under internal pressure loading. The suggested models provide an exact solution for stresses, strains and displacement on the sandwich pipe, which is made of epoxy material for the core layer and reinforced materials with an alternate-ply for the skin layers. The aim of this analysis is to evaluate the potential applications of jute and pineapple leaf fiber (PALF) bio-fibers in order to replace glass synthetic fibers generally employed in sandwich pipes. In this subject, a failure analytical analysis was developed using TSAI-WU criterion. The results of stress, strain and displacement distribution through the thickness are presented for the analytical and numerical models. The comparison between the both models results show a very good agreement. In order to increase the rigidity of a biocomposite sandwich and reduce the gap compared with a synthetic sandwich, a gradual reinforcing of layer numbers was chosen, which permitted the best behavior. The ultimate pressure and safety factors obtained by increasing biocomposite layers are significant for composite transportation pressure pipelines, especially for sandwich pipe based on PALF/epoxy.

A REVIEW OF NATURAL GAS-HYDROGEN BLENDING IN PIPELINE SUPPLY AND DISTRIBUTION

The reduction of greenhouse gases is an assumed objective of the European Community. Thus, in the future, natural gas transport and distribution pipelines will also have to deal with ensuring the transport of mixtures formed between hydrogen, biomethane and natural gas from fossil resources. Considering the increase in the amount of biomethane and the increase in the amount of green hydrogen produced, these fuels’s use in natural gas distribution networks is expected. The article presents an analysis of hydrogen production methods as well as numerical models of hydrogen transportation and mixing with natural gas. Also, there are presented the results obtained at the international level regarding the thresholds for the use of hydrogen in the fossil fuel of natural gas type, as well as the effects produced by the presence of this gas on the transport and supply systems. Numerical models of mixing and dynamic behavior of the new fuel obtained are also analyzed.

Microbial corrosion behavior of pipeline steels in simulation environment of natural gas transportation pipeline

Microbial corrosion behavior of pipeline steels in simulation environment of natural gas transportation pipeline

Resource Conservation as the Main Factor in Increasing the Resource Efficiency of Russian Gas Companies

The complex modern trends in the growth of the consumption of raw hydrocarbon materials around the world, and as a consequence their accelerated depletion, have forced oil and gas industry enterprises to identify progressive resource-saving methods and technologies. Such methods could enable the environmental and technological effects of production processes to be achieved under conditions of sustainable economic development and with a policy of balanced consumption and resource provision. This research is devoted to the improvement of the scientific and methodological foundations and the development of predictive and analytical tools for assessing the efficiency of resource use in gas industry enterprises. With the application of the proposed instruments, we carry out simulation modeling of the efficiency of natural gas production, processing and pipeline transportation companies. In the course of a comparative analysis of the efficiency indicators for Russian gas companies, a resource-efficient variant of their development is selected and the most promising business projects are identified. Three branch companies of the Russian gas industry are accepted as the objects of the research in this study. As a result of the conducted approbation process, it is revealed that the existing practice of assessing consumption and resource provision in companies in the industry, as well as the use of methods and approaches to resource conservation, does not have a single and complex character. The methodology proposed by the authors makes it possible to approach industry companies with the same set of indicators, systematize and calculate them, identify existing unused reserves for resource conservation and identify promising resource-efficient projects.

Machine learning models for fast selection of amino acids as green thermodynamic inhibitors for natural gas hydrate

Natural amino acids are non-toxic thermodynamic hydrate inhibitors without negative environmental impact, but it is difficult to accurately select the appropriate amino acid as a quick response to the operational conditions changes in the natural gas pipeline. The objective of this study was to develop mathematical models to predict the hydrate formation temperature (HFT) in presence of amino acids, capture the relationship between amino acid structure properties and their hydrate inhibition strength, and determine the optimal type and concentration to use. The HFT prediction was evaluated using multiple linear regression (MLR) and three machine learning methods including random forest (RF), M5 Rule (M5R) and support vector machine (SVM). After parameter optimization using the trial-and-error method, the coefficient of determination (R2) of the four models were 0.9328, 0.9793, 0.9795 and 0.9980, respectively. The SVM prediction of HFT outperformed other models as the root mean square error (RMSE) was 83%, 76% and 69% lower than that of the MLR, RF and M5R, respectively. Results also demonstrated that the relative importance of the amino acid concentration to the hydrate phase equilibrium was 5-fold higher than that of the intrinsic properties of the amino acid molecular. The SVM model proposed in this study served an easy-to-use tool for reliable prediction of HFT by just providing a new set of input data. This made it possible to accurately determine the minimum concentration of amino acids to be used during the gas pipeline transportation.

Enhanced anti-microbial corrosion of nano-CuO-loaded Ni coatings on pipeline steels in simulation environment of natural gas transportation pipeline

Bacteria were introduced into natural gas transportation lines and reacted with CO2 and corrosive ions to cause severe corrosion when natural gas was captured by water drive methods. Anti-microbial corrosion of natural gas pipeline is an important prerequisite for pipeline steel protection. An Ni coating with high corrosion resistance was prepared on the surface of pipeline steel by electrodeposition method, and CuO nanoparticles were introduced to obtain anti-microbial function. A simulated corrosion environment in a natural gas pipeline was designed to investigate the corrosion resistance behavior of the CuO-loaded Ni coating under the combined action of CO2, Cl−, and sulfate-reducing bacteria (SRB) and the inhibition effect of CuO on the microbial corrosion of SRB. The corrosion rate of nano-CuO-loaded Ni coatings at 15 days was only 41.8% of that of the pipeline steel. In addition to the corrosion resistance of the Ni coating, the corrosion rate was reduced because nano-CuO reduces the probability of corrosion reactions and has an anti-microbial effect on SRB. This coating with anti-microbial and anticorrosive functions has important engineering application value for the microbial corrosion protection of natural gas pipelines.

Flame propagation characteristics of methane explosion under different venting conditions

Air mixed with methane commonly causes explosion accidents. Explosion vents can discharge the explosion pressure and release energy to reduce the explosion impact. Explosion vents are widely applied to gas transportation pipelines and other pressure equipment. To determine the influence of explosion vent areas and types on dynamic characteristics of methane flame propagation, in this study, an explosion pipe system was established to explore the effects of the 22.89-cm2 circular (1#), 15.20-cm2 circular (2#), 9.07-cm2 circular (3#), and 15.20-cm2 cross-shaped (4#) vents on flame propagation of methane explosion and to compare these effects with those of a closed pipe. The experimental results indicated that the explosion vent accelerated flame propagation velocity (v) and considerably reduced explosion pressure (P) and flame temperature (T) compared with the closed pipe results. v, T, and P reached maximum values at 10 vol% methane concentration. As the vent area increased, the v of the three circular vents increased. Flame propagation velocity in 1#, 2#, and 3# increased by 23.13 %, 21.57 %, and 4.55 % compared with that of the closed pipe (13.40 m/s), respectively. Compared with the closed pipe values of 0.973 MPa and 1678.13℃ for P and T, decreases of 10.30 %, 12.50 %, 38.00 %, and 1.82 %, 10.53 %, 11.22 % were observed in 1#, 2#, and 3#, respectively. Under equal explosion vent areas (15.20 cm2) but different vent types (2# circular and 4# cross), as the equivalent diameter of vents increased, P and T decreased by 12.50 %, 20.91 %, and 10.53 %, 10.01 %, and v increased by 21.57 % and 12.61 %.

Numerical Investigation of the Strain Characteristics of a Natural Gas Transportation Pipeline Crossing Tunnel

To ensure the safe operation of a natural gas transportation pipeline (NGTP) crossing tunnel, a model is established to analyze the strain characteristics. Some factors affecting the strain are considered in this paper. The results show that the strain failure of a NGTP crossing tunnel may occur in the two elbows of the NGTP located at the tunnel entrance and the position in contact with the fixed pipe clamp near the tunnel entrance. At the same time, the strain of the NGTP crossing tunnel is obviously affected by the temperature change of natural gas. So, the temperature change should be controlled within 8 K in the actual operation process. The wall thickness, the length of the NGTP, and the slope angle of the crossing tunnel are also main factors to affect the strain of the NGTP crossing tunnel, while the operation pressure and mountain slope angle have little effect when the operation pressure is 6–11 MPa. The maximum value of Mises equivalent strain is also obviously affected by the pipe diameter when it is more than 273 mm. Meanwhile, a prediction model for the maximum value of Mises equivalent strain is also established by the nonlinear fitting method and the deviation is within ±15% between the calculations and simulation results. The above conclusions will provide a theoretical basis and data support for the safe operation and design of NGTP crossing tunnels.

Corrosion Inhibition Investigation of Small Organic Inhibitor on API5LX60 Steel in 3.5% NaCl Solution with CO2 Saturation

CO2 corrosion has emanated as a significant concern in the oil/gas industry owing to the aging of its oilfields. Thus, corrosion protection is significant for maintaining the integrity and sustainability of pipelines, surface facilities, and downhole tools in the oil/gas sector. The present study evaluates the corrosion inhibitory properties of three oxazolone derivatives in CO2 saturated 3.5 weight% NaCl solution against API5LX60 carbon steel used in certain wells and oil/ gas transportation pipelines. The inhibitory behavior was investigated utilizing gravimetric and electrochemical techniques viz. EIS, PDP, and LPR. Electrochemical and Gravimetric technique results were in congruence. EIS asserts capacitive behavior, and PDP affirms oxazolones as mixed inhibitors. SEM and SEM-EDX confirmed the formation of a protective layer by adsorption. At an optimum inhibitor concentration of 200 ppm, inhibitor I exhibited 91.30% inhibition—linear correlation coefficient R2 value of 0.99 avowed adsorptions via Langmuir Isotherm.

Numerical study on harmful boundary of above-ground section leakage of natural gas pipeline

Natural gas has incomparable advantages compared with other energy, but the accidents caused by natural gas pipeline transportation cannot be ignored. In order to reduce the accident damage, it is necessary to master the concentration distribution of leaked gas in the atmosphere scientifically. The main contribution of this research is to predict the harmful boundary of gas diffusion. Numerical simulation was used to establish the leakage diffusion model of natural gas pipeline exposed to atmosphere. The influences of leakage rate, leakage diameter and wind speed on the harmful boundary of gas were studied. The results show that harmful boundary reaches a stable state after a period of leakage. Leakage rate and leakage diameter contribute to vertical height of harmful boundary, and have little effect in the horizontal direction. Wind speed is the main factor affecting gas diffusion path. Increasing wind speed results in decrease of vertical height and increase of horizontal distance of harmful boundary, gas diffusion develops near the ground in the downwind direction. The quantitative formula between harmful boundary of gas diffusion and influencing factors is proposed. This work has a great guiding significance for emergency rescue work in engineering.

Electromagnetic Pigging System Based on Sandwich Differential Planar Coil

In-pipeline inspection is an important precontrol method to ensure the safety of oil and gas pipeline transportation. This article proposes an electromagnetic in-pipe detector based on passive resonance-enhanced differential planar coils to detect defects on the inner surface of pipes. Both qualitative and quantitative analyses of pipeline defects and damage are developed. The introduction of passive resonant coils is shown to significantly improve the detection capability of the sensor. This is coupled with the establishment of a theoretical derivation model of the proposed structure. The hardware platform of the laboratory system has been built, and an eddy current internal detector suitable for 8-in-diameter pipes is developed and integrated into the system. Numerical simulations and experimental verifications on flat defects and pipe defects have been undertaken. The obtained results have shown that the real defects have been correctly detected, and the system is effective, reliable, and efficient.

Synthesis and evaluation of poly (N-vinyl caprolactam)–co-tert-butyl acrylate as kinetic hydrate inhibitor

• A new KHI PVCap- co -TBA was synthesized and evaluated in different hydrate forming systems. • The relationship between the dosage of KHI and the inhibition performance was analyzed. • PPG was proposed as a good synergist for PVCap- co -TBA with concentration of 1.0 wt%. Low dosage kinetic hydrate inhibitors (KHIs) are a kind of alternative chemical additives to high dosage thermodynamic inhibitors for preventing gas hydrate formation in oil & gas production wells and transportation pipelines. In this paper, a new KHI, poly ( N -vinyl caprolactam)– co - tert -butyl acrylate (PVCap- co -TBA), was successfully synthesized with N -vinyl caprolactam (NVCap) and tert -butyl acrylate. The kinetic inhibition performances of PVCap- co -TBA on the formations of both structure I methane hydrate and structure II natural gas hydrate were investigated by measuring the onset times of hydrate formation under different conditions and compared with commercial KHIs such as PVP, PVCap and inhibex 501. The results indicated that PVCap- co -TBA outperformed these widely applied inhibitors for both structure I and structure II hydrates. At the same dosage of KHI, the maximum tolerable degree of subcooling under which the onset time of hydrate formation exceeded 24 hours for structure I hydrate was much lower than that for structure II hydrate. The inhibition strength increased with the increasing dosage of PVCap- co -TBA; The maximum tolerable degree of subcooling for the natural gas hydrate is more than 10 K when the dosage was higher than 0.5% (mass) while it achieved 12 K when that dosage rose to 0.75% (mass). Additionally, we found polypropylene glycol could be used as synergist at the dosage of 1.0 % (mass) or so, under which the kinetic inhibition performance of PVCap- co -TBA could be improved significantly. All evaluation results demonstrated that PVCap- co -TBA was a very promising KHI and a competitive alternative to the existing commercial KHIs.

Research on thermal insulation performance of composite energy storage pipeline with phase change materials

The oil and gas pipeline transportation technology is the key to the surface production of oil field, and the pipeline insulation technology plays an important role in realizing the safe, stable and energy-saving transportation of crude oil. The composite energy storage pipeline with PCM not only has thermal insulation performance, but also can greatly prolong the safe shutdown time when the shutdown condition occurs by taking advantage of the storage and discharge energy characteristics of PCM. In this paper, the reasonable structural parameters of composite energy storage pipeline with PCM were determined by comparing the effective insulation time of three typical pipelines under the same working conditions and combining with thermal resistance method. Considering the nonlinear latent heat release and phase change characteristics of crude oil, a pipe-PCM-oil coupling thermodynamic model was established for the composite insulation pipeline, and numerical solution was carried out. The heat transfer characteristics of composite energy storage pipeline with PCM under different working conditions were analyzed, and the effects of physical properties and structures of different PCM on the thermal insulation performance of composite energy storage pipeline were compared. The research results can provide theoretical support for the safe shutdown scheme of oil pipeline.

The Application of A Combined Computational Fluid Dynamics (CFD) Artificial Neural Network (ANN) to Increase The Prediction Accuracy of Sediment Grading in Subsea Pipes: A Literature Review

In recent years, the implementation of subsea pipelines for oil and gas transportation has increased. One of the important aspects of the design process of the subsea pipeline is scour prediction. Scouring causes the subsea pipeline to lose its support and is susceptible to failure due to deflection. This paper presents the result of a literature review of scouring-related research to obtain a method to increase scouring prediction accuracy. Based on the literature research, it is known that the errors found in Computational Fluid Dynamics (CFD) are mainly affected by the flow models. Existing flow models cannot fully represent the complexity of turbulent flow that occurs during the scouring process. Artificial Neural Network (ANN) can reduce the error value. But, the CFD-ANN hybrid methods can potentially decrease the error value by about 20% more than CFD. Therefore, the CFD-ANN hybrid method is expected to be a new method that could be used to predict subsea pipeline scouring in the oil and gas industry.

Meniscus inspired flexible superhydrophobic coating with remarkable erosion resistance for pipeline gas transmission

Inspired by human meniscus, a superhydrophobic inner pipeline coating with has been developed to mitigate the erosion and corrosion damages to gas transportation pipeline. The erosion-resistant coating, consisting of modified TiO2 nanoparticles (NPs), multi-walled carbon nanotube (CNTs), and epoxy resin (EP), is built on a buffer layer made of polydimethylsiloxane (PDMS). The optimized buffer layer thickness (100 μm) was determined by finite element simulation when mixing ratio between the curing agent and PDMS was 1:30. The erosion resistance of the prepared coating was quantified by an erosion ring experiment. Finally, erosion resistance of materials produced by different filler types (fibrous and spherical) were compared. The erosion resistance of the material is significantly improved by the tensile force of the fiber filler, similar to the steel in reinforced concrete. The result shows that the buffer-structure coating can reduce the magnitude of erosion rate significantly. Compared to the coating with no buffer structure, the maximum reduction of erosion rate is up to 37.55 %. In addition, the water contact angle (CA) of the sample could maintained over 150° after various mechanical shocks, such as 350 times of 90° bending test, 1500 times of sand impact test, and 4H pencil hardness test. Compared with the 316L steel sample, the corrosion potential of the coating in 3.5 wt% NaCl solution increased from −0.18 V to 0.04 V, making it potentially applicable for the corrosive environment of submarine pipelines.

On the Main Legal Risks and Countermeasures of International Oil and Gas Pipeline Transportation

On the Main Legal Risks and Countermeasures of International Oil and Gas Pipeline Transportation

Aerodynamic Characteristics of Supersonic Separator for Natural Gas Processing

Natural gas is a key energy source to achieve the carbon peaking and carbon neutrality goals in China. Dehydration and de-hydrocarbon process is crucial for pipeline transportation of natural gas since water and hydrocarbons in the natural gas would condense to cause corrosion and freeze-blockage in the pipeline. The supersonic separator is innovative low-temperature separation equipment characterized by a simpler equipment structure and higher refrigeration efficiency than the traditional device. In this paper, the numerical analysis is employed to predict the performance of the supersonic separator. The results show that this separator can reach an advanced level compared with others. The separator cannot start-up as the inlet-outlet pressure ratio is lower than1.29, and the minimum pressure ratio needed for normal work is 1.39. Under normal operating conditions, total pressure loss is about 25.4%, the minimum temperature is about 213K, and the mean rotation speed is about 170m/s.