Pipeline Operation Research Articles

CO2 corrosion prediction on 20# steel under the influence of corrosion product film

Based on corrosion thermodynamics and kinetics, considering the multi-field coupling effects of fluid flow, electrochemical reaction and mass transfer process, a new corrosion prediction mechanistic model was proposed by introducing the influence factor of corrosion product film on diffusion coefficient of ion mass transfer, which is based on the CO 2 corrosion prediction model proposed by Nesic et al. The influence of temperature, flow rate and pH value on CO 2 corrosion behavior on 20# steel was studied by orthogonal tests. Scanning electron microscopy (SEM) and energy spectrum analysis (EDS) was used to analyze the surface and cross section morphology of the corrosion product film, and the thickness of the corrosion product film was measured. The results show that the introduced influence factor can simplify the ion mass transfer calculation in the presence of corrosion product film, and the relative error between the predicted value of the modified model and the experimental results is satisfactorily controlled less than 10%. Compared with the prediction model without considering the influence of corrosion product film, the influence factor can effectively correct the high prediction value of the mechanistic model under the influence of corrosion product film, improve the accuracy and applicability of corrosion prediction, and provide important theoretical guidance for the design, manufacturing, operation and maintenance of oil and gas production pipelines and related facilities.

Optimizing Data Pipelines for Machine Learning in Feature Stores

Data pipelines (i.e., converting raw data to features) are critical for machine learning (ML) models, yet their development and management is time-consuming. Feature stores have recently emerged as a new "DBMS-for-ML" with the premise of enabling data scientists and engineers to define and manage their data pipelines. While current feature stores fulfill their promise from a functionality perspective, they are resource-hungry---with ample opportunities for implementing database-style optimizations to enhance their performance. In this paper, we propose a novel set of optimizations specifically targeted for point-in-time join, which is a critical operation in data pipelines. We implement these optimizations on top of Feathr: a widely-used feature store, and evaluate them on use cases from both the TPCx-AI benchmark and real-world online retail scenarios. Our thorough experimental analysis shows that our optimizations can accelerate data pipelines by up to 3× over state-of-the-art baselines.

Numerical Simulation of Particle Transport in Semi-Dry Desulfurization Slurry

Among the desulfurization technologies, semi-dry technology is widely used, with the advantages of low cost, low water consumption, and no secondary effluent, which is favored by most domestic and foreign users. For a power plant, the slurry after desulfurization of a semi-dry desulfurization plant has the phenomenon of pipeline deposition in the process of pipeline transportation, which needs to be cleaned every short period, increasing unnecessary costs. Therefore, it is important to master the deposition law to allow safe and productive pipeline operation and reduce unnecessary waste.

Effect of Pipe Steel Chemical Composition and Structural Characteristics on Corrosion Resistance under Western Siberia Oilfield Pipeline Operating Conditions

Effect of Pipe Steel Chemical Composition and Structural Characteristics on Corrosion Resistance under Western Siberia Oilfield Pipeline Operating Conditions

ON THE ISSUE OF TRANSPORTATION OF LIQUEFIED CARBON DIOXIDE

Link for citation: Vanchugov I.M., Rezanov K.S., Shestakov R.A. On the issue of transportation of liquefied carbon dioxide. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 190-209. In Rus. The relevance of the study is caused by the need to capture and utilize one of the main types of greenhouse gases – carbon dioxide (CO2). This need is primarily related to the ever-increasing CO2 emissions, three quarters of which are accounted for by the combustion of various fuels. The main aim is to analyze and systematize international methods for calculating the pipeline transport of liquefied carbon dioxide (LCO2) to determine differences in numerical results, including factors taken into account and not taken into account in the methods under consideration, as well as to analyze water transport type as an alternative to pipeline transport. Objects: liquefied carbon dioxide, a pipeline for transporting LCO2. Methods: numerical modeling of LCO2 pipeline transport according to international methods to estimate the required diameter capable of providing a given pumping flow rate, analysis of the results obtained. Results. The authors have carried out a review of existing methods for calculating LCO2 pipelines, carried out numerical modeling and analysis of the results were, during which it was revealed that most models ignore the influence of impurities, which, however, affect the technological parameters of operation and modeling of LCO2 pipelines, which will lead to inaccuracies in their design and operation. In addition, it was found that the fluid velocity in the pipeline is calculated according to the parameters in the initial section, which corresponds to its minimum value in the pipeline, and is assumed to be equal to it throughout the pipeline without taking into account the expansion of LCO2 from changes in temperature and pressure along its length and, consequently, without taking into account additional pressure losses and changes in other technological parameters that they can directly affect the operational safety and economic efficiency of the designed or operated LCO2 pipeline. It should also be noted that the diameter determination equations depending on the length of the pipeline are not suitable for estimating the optimal diameter of the pipeline. As for alternatives to pipeline transport, first of all, it is worth noting the possibility of transportation by tankers over long distances or the possibility of using LCO2 to increase the flow rate of deposits on the shelf and in hard-to-reach places of the coastal zone.

Research on Internal Shape Anomaly Inspection Technology for Pipeline Girth Welds Based on Alternating Excitation Detection.

Abnormal formation of girth weld is a major threat to the safe operation of pipelines, which may lead to serious accidents. Therefore, regular inspection and maintenance of girth weld are essential for accident prevention and energy security. This paper presents a novel method for inspecting abnormal girth weld formation in oil and gas pipelines using alternating excitation detection technology. The method is based on the analysis of the microscopic magnetic variations in the welded area under alternating magnetic fields. An internal inspection probe and electronic system for detecting abnormal girth weld formation were designed and developed. The system's capability to identify misalignment, undercutting, root concavity, and abnormal formation height of girth weld was tested by numerical simulation and experimental study. The results show that the detection system can effectively identify a minimum misalignment of 0.5 mm at a lift-off height of 15 mm. The proposed method offers several advantages, such as rapid response, low cost, non-contact operation, and high sensitivity to surface flaws in ferromagnetic pipelines.

Pilot-scale testing of natural gas pipeline monitoring based on phase-OTDR and enhanced scatter optical fiber cable

In this paper, we present the results of lab and pilot-scale testing of a continuously enhanced backscattering, or Rayleigh enhanced fiber cable that can improve distributed acoustic sensing performance. In addition, the Rayleigh-enhanced fiber is embedded within a tight buffered cable configuration to withstand and be compatible for field applications. The sensing fiber cable exhibits a Rayleigh enhancement of 13 dB compared to standard silica single-mode fiber while maintaining low attenuation of ≤ 0.4 dB/km. We built a phase-sensitive optical time domain reflectometry system to interrogate the enhanced backscattering fiber cable both in lab and pilot-scale tests. In the laboratory experiment, we analyzed the vibration performance of the enhanced backscattering fiber cable and compared it with the standard single-mode telecom fiber. Afterward, we field validated for natural gas pipeline vibration monitoring using a 4-inch diameter steel pipeline operating at a fixed pressure level of 1000 psi, and a flow rate of 5, 10, 15, and 20 ft/s. The feasibility of gas pipeline monitoring with the proposed enhanced backscattering fiber cable shows a substantial increase in vibration sensing performance. The pilot-scale testing results demonstrated in this paper enable pipeline operators to perform accurate flow monitoring, leak detection, third-party intrusion detection, and continuous pipeline ground movement.

A New Method for Evaluating Natural Gas Pipelines Based on ICEEMDAN-LMS: A View of Noise Reduction in Defective Pipelines

As the main means of energy transportation, pipelines have the characteristics of 24 h uninterrupted transportation, low cost, strong transmission capacity, and low risk, and they have become an important device for natural gas transportation. However, due to defects caused by the pipeline itself and external forces, it is easy for natural gas leakage to cause major accidents, serious environmental pollution, and huge losses of life and property. Traditional pipeline defect detection technology can be interfered with by a large number of noise signals when collecting defect signals, and the noise reduction method is simple but has poor accuracy, so it cannot directly obtain effective pipeline defect information from the signal and cannot effectively improve the emergency intensity and emergency level of pipeline operation and maintenance management. Therefore, a new noise reduction method, ICEEMDAN-LMS, for natural gas pipelines is proposed in this paper, and the method is calculated and tested in detail. The effectiveness of the new method is verified through the analysis of a pipeline defect signal and normal signal. Moreover, the proposed method can reduce noise more effectively than conventional methods, which has clear value in engineering applications. Importantly, this noise reduction method not only provides a reliable basis for the intelligent diagnosis of pipeline defect signals, but can also be an important reference for helping management departments to make decisions and emergency plans and formulate on-site treatment programs.

Greenhouse gas emissions from U.S. crude oil pipeline accidents: 1968 to 2020

Crude oil pipelines are considered as the lifelines of energy industry. However, accidents of the pipelines can lead to severe public health and environmental concerns, in which greenhouse gas (GHG) emissions, primarily methane, are frequently overlooked. While previous studies examined fugitive emissions in normal operation of crude oil pipelines, emissions resulting from accidents were typically managed separately and were therefore not included in the emission account of oil systems. To bridge this knowledge gap, we employed a bottom-up approach to conducted the first-ever inventory of GHG emissions resulting from crude oil pipeline accidents in the United States at the state level from 1968 to 2020, and leveraged Monte Carlo simulation to estimate the associated uncertainties. Our results reveal that GHG emissions from accidents in gathering pipelines (~720,000 tCO2e) exceed those from transmission pipelines (~290,000 tCO2e), although significantly more accidents have occurred in transmission pipelines (6883 cases) than gathering pipelines (773 cases). Texas accounted for over 40% of total accident-related GHG emissions nationwide. Our study contributes to enhanced accuracy of the GHG account associated with crude oil transport and implementing the data-driven climate mitigation strategies.

Experimental and OLGA Modeling Investigation for Slugging in Underwater Compressed Gas Energy Storage Systems

Underwater compressed gas energy storage (UW-CGES) holds significant promise as a nascent and viable energy storage solution for a diverse range of coastal and offshore facilities. However, liquid accumulation in underwater gas pipelines poses a significant challenge, as it can lead to pipeline blockages and energy transmission interruptions and adversely impact pipeline operation. In this paper, experimental and Oil and Gas Assays (OLGA) simulation studies have been conducted on the formation process of slug flow in pipelines. Firstly, experiments are conducted to capture high-speed camera images of slug flow under various liquid accumulation volumes and inclination angles. Subsequently, an OLGA model is developed to verify the experimentally observed flow regime, pressure, and slugging speed. Therefore, the flow regime verification results exhibit substantial consistency, and pressure variations display uniform trends, with an average slugging velocity error of 6.42%. The results indicate that the formation of slug flow involves three distinct stages: slug flow growth, ejection, and backflow. By analyzing slug flow, it can gain insights into the relationship between pressure and slug flow formation, exposing the sensitivity of this phenomenon to pressure fluctuations. These results further enhance recognition of the operational status of UW-CGES pipelines and provide support for safe operation.

A Methodology to Combine Shaking and Ground Failure Models for Forecasting Seismic Damage to Buried Pipeline Networks

ABSTRACT How does an earthquake affect buried pipeline networks? It is well known that the seismic performance of buried pipelines depends on ground failures (GFs) as well as strong ground shaking (SGS), but it is unclear how the various types of earthquake hazards should be collectively combined, as existing methodologies tend to examine each of the earthquake hazards separately. In this article, we develop a probability-based methodology to consistently combine SGS with three types of GF (surface faulting, liquefaction, and landslide) for forecasting seismic damage in buried pipeline networks from a given earthquake rupture scenario. Using a gas transmission pipeline example, we illustrate how the proposed methodology enables others (e.g., researchers, pipeline operators who manage distribution lines, and consultants) to modularly combine various models such as those for estimating probability of GF, permanent ground displacements, and pipeline fragility. Finally, we compare the proposed methodology against the Hazus methodology to explore implications from considering each hazard one at a time.

The optimum use of high-strength steel in the construction of gas transmission pipeline

PurposeThe aim of this study is to assess the opportunity for the development of hydrocarbon transportation using high-strength steel (HSS) in pipeline construction in terms of cost savings and reliability.Design/methodology/approachSeveral optimizations of pipeline design and operations were performed to estimate the total life-cycle cost variation associated with different grades of high-strength steel. The generalized reduced gradient (GRG) method was used in an Excel table to determine optimal total life cycle each pipeline. Variables used in this optimization with respect to each steel grade were as follows: pipeline external diameter, wall thickness, number of compression stations and installed power in each compression station. The reliability of a pipeline with optimal cost was assessed to highlight the impact of steel grade on pipeline reliability.FindingsThe study showed that the cost reduction is strongly dependent on the adopted gas pipeline configuration. The number of compression stations and external diameter are the main factors influencing the pipeline total life cycle cost, while the steel price seems to have a minor effect, the reduction of the gas pipeline total life cycle does not exceed 5% even with a 50% difference in pipe steel prices between X70 and X100 steels. On the other side, for the same external diameter, X100 steel presents better pipeline reliability against carbonic corrosion compared to X70 steel.Practical implicationsThe main contribution of this study is to provide a decision-support tool to help pipeline constructors enhance the profitability of natural gas transmission pipelines. The optimization method used is simple to use for design engineers during a feasibility study.Originality/valueThe present study presents one step to fill the gap concerning the question of balancing the trade-off between cost savings and structural reliability in high-strength steel pipelines during the early stages of feasibility studies. The optimal design and operations parameters ensuring cost savings on total life cycle costs are identified via an optimization method. The impact of selected optimal parameters on the long-term pipeline service life was estimated via a structural reliability analysis.

Experimental study and chemical affinity model on the inhibition of CO2 gas hydrate formation

Natural gas and water can form complex cage crystals in oil and gas pipelines under certain conditions. The natural gas hydrate formed after crystal clustering can block the pipeline and affect the operation efficiency of the pipeline, and even cause equipment damage, bringing economic and security problems to enterprises. In the present study, we experimentally investigated the inhibition of CO2 formation hydrate using attapulgite (ATP) and glucose (GLC). The kinetic influence on the formation of CO2 hydrate by the complex pairing of kinetic inhibitor ATP is conducted under the working conditions of 277.15 K and 3.5 MPa. The effect of compound inhibitors on the temperature and pressure conditions, growth process and gas consumption of hydrate formation are revealed. The chemical affinity model of CO2 hydrate formation under a compound inhibitor system is derived and established based on experimental studies. The results show that the combination of GLC and ATP can inhibit the formation of CO2 hydrate to varying degrees, prolong the induction time of hydrate, and reduce the consumption of CO2. The optimized experimental studies demonstrate that the best inhibitory compound system is 15 mg/mL GLC + 1.00 mg/mL ATP. Compared with the pure water system and single 15 mg/mL GLC system, the induction time is extended by 122.61% and 122.23%, while the gas consumption is reduced by 23.72% and 3.41%. The results provide new ideas and methods for the prediction of hydrate formation in the compound inhibitor system for the safe operation of oil and gas pipelines.

Experimental Study on Mechanical Response of Oil and Gas Pipelines under Ground Subsidence

At present, accidents of buried pipelines caused by localized ground subsidence are reported frequently. Understanding the mechanical response of pipe soil during subsidence is of great significance to the safe operation of buried pipelines. This paper studies the stress state of buried oil and gas pipelines and their surrounding soil through a series of large-scale model tests in the process of localized ground subsidence. The experiment results show that during the process of subsidence, the axial and hoop strain of the pipeline increases with the expansion of the subsidence area and the subsidence amount. The subsidence amount has a relatively greater influence, and the distribution characteristics of the pipeline strain present obvious regional characteristics. The earth pressure around the pipe shows different changes in the process of subsidence, among which the earth pressure on the upper part of the pipe is the main one. The research results can provide a certain reference for the design and calculation of oil and gas pipelines under foundation settlement.

Study on the Erosion Characteristics of Non-spherical Particles in Liquid-solid Two-phase Flow

Elbow erosion, defined as wall thinning due to the continuous interactions between solid particles and surface, is a common phenomenon in catalyst addition/withdrawal pipeline systems used in residual oil hydrogenation units. This form of erosion can seriously affect the reliable pipeline operation. The present paper describes the construction of realistic cylindrical catalyst particles using the multi-sphere clump method and computational fluid dynamics/discrete element model simulations to study the erosion of pipe walls under different inlet velocities and particle aspect ratios. An optical shooting experiment is carried out to ensure the accuracy of the calculation method, and the model performance is compared using several existing drag models. The results show that the drag model of Haider & Levenspiel is more accurate than the others in revealing the actual cylindrical particle flow. A higher inlet velocity is observed to increase the kinetic energy of the particles and affect their spatial distribution. Specifically, when the Stokes number is greater than 113.7, the position of the maximum erosion rate shifts from the elbow’s outer wall to the inner wall. Cumulative contact energy is introduced to quantify two different types of particle-wall contacts. With a growing particle aspect ratio, the proportion of tangential energy gradually increases, which indicates that sliding is the main contact mode. The results presented in this paper provide a reference for engineering erosion calculations.

Prediction of Physical Properties and Phase Characteristics of Ethane and Ethane Mixture in the Ethane Pipeline

In order to realize the safe transportation of liquefied ethane pipeline in the Oilfield of China, it is necessary to fully study the process of pipeline replacement, operation and shutdown. The accurate calculation of physical property parameters and critical parameters is the basis of studying the gas-liquid two-phase flow and heat and mass transfer process of liquefied ethane in the pipeline. In this paper, different equations of states (EOSs) were used to predict the physical properties (such as density, dew point and dynamic viscosity) of ethane or ethane mixture, and the predicted results were compared with the corresponding experimental data from the literature. The prediction performance of different EOSs were evaluated by using two evaluation indicators, including average absolute deviation (AAD) and average relative deviation (ARD). The results showed that the PR-Peneloux EOS has the best performance for predicting the density of CH4-C2H6-N2 mixture with an ARD value of 4.46%; for predicting the dew point, the BWRS EOS exhibits the superior performance with an ARD value of 0.58%; and for predicting dynamic viscosity, the SuperTRAPP formula has the smallest calculation error, with an ARD value of 1.33%. Considering the comparison results of the calculation accuracy of density, dew point and dynamic viscosity of ethane or ethane mixture by using different EOSs, PR-Peneloux EOS was recommended to calculate the phase characteristics in the process of ethane pipeline replacement operation. The phase characteristics of ethane for pipeline transport in the oilfield of China were obtained. The critical temperature is 32.79℃ and the critical pressure is 4.97 MPa.

Failure Risk Prediction Model for Girth Welds in High-Strength Steel Pipeline Based on Historical Data and Artificial Neural Network

Pipelines are the most economical and sensible way to transport oil and gas. Long-distance oil and gas pipelines consist of many steel pipes or pipe fittings joined by welded girth welds, so girth welds are an essential part of pipelines. Owing to the limitations of welding conditions and the complexity of controlling weld quality in the field, some defects are inevitably present in girth welds and adjacent weld areas. These defects can lead to pipeline safety problems; therefore, it is necessary to perform failure risk assessment of pipeline girth welds. In this study, an artificial neural network model was proposed to predict the failure risk of pipeline girth welds with defects. Firstly, many pipeline girth weld failure cases, pipeline excavation, and inspection data were collected and analyzed to determine the main factors influencing girth weld failure. Secondly, a spatial orthogonal optimization method was used to select training samples for the artificial neural network model to ensure that the training sample set could cover the feature space with a minimum number of samples. Thirdly, a prediction model based on BP neural networks was established to predict the failure risk levels. The training dataset/testing dataset was 602/4215, and the prediction accuracy for all risks of girth welds achieved an acceptable level. This study can provide a valuable reference for pipeline operators to prevent pipeline accidents.

ASSESSMENT OF KARST-SUFFUSION HAZARD OF THE CHAYANDA–ESPO OIL PIPELINE IN YAKUTIA

Link for citation: Nechaev D.A., Strokova L.A. Assessment of karst-suffusion hazard of the Chayanda–ESPO oil pipeline in Yakutia. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 78-92. In Rus. The study is relevant due to the need to identify dangerous sections of oil and gas pipelines located in underdeveloped and sparsely populated areas, due to the development of dangerous geological processes. This study aims to assess the intensity and forecast the development of karst-suffusion processes within the pipeline route located in southern Yakutia, and to determine the most significant factors that activate this process. Methods: processing engineering and geological survey data, digitization of geological maps and decoding satellite images to build factor maps that affect the activation of the karst process: geological structure of the route; curvature, slope, surface exposure; map of surface drainage density and density of total tectonic fracturing. We created a map of the density of karst occurrences along the route according to the route survey and data from engineering and geological surveys during construction. We compiled a map of the susceptibility of the route territory to the development of karst-suffusion processes based on the Frequency Ratio method. Results. We carried out a description of the engineering and geological conditions of the pipeline route. To assess the karst-suffusion hazard of the pipeline route, calculations were made of the expected sizes of sinkholes in the base of structures using the method of G.M. Shakhunyants. Using the method of the ratio of particulars, the correlations between factors and foci of karst occurrences along the pipeline route were obtained. The susceptibility map developed on the basis of these results makes it possible to determine specific site boundaries for determining solutions for monitoring the development of the exogenous process and optimizing the pipeline operation processes. Therefore, the application of such methodology can be applied to other extended gas and oil pipelines located in difficult geological conditions.

PIPE PROTECTION FROM CORROSION UNDER THERMAL INSULATION

Oil in the northern regions has a positive solidification temperature, so it needs to be heated to ensure pumping. Oil must have a high positive temperature along the entire pipeline length, which leads to a number of issues related to maintaining a positive temperature of oil in the pipeline along its entire length. Taking into account all the geological and climatic features of the Far North, for reliable and safe operation of the oil pipeline it is necessary to ensure the required temperature of the transported product, preventing pumping stops and preventing energy consumption overruns.
 During the operation of pipelines with thermal insulation, moisture is formed in the thermal insulation layer for a number of reasons. Water gets under thermal insulation in two ways: as a result of condensation or comes from the outside. In addition, the thermal insulation itself can absorb and retain water, which subsequently turns out to be under insulation. Condensation may occur when the operating temperature of the surface changes.
 Prolonged exposure to leaked or condensed moisture on the outer wall of the pipeline is the cause of corrosion under thermal insulation. The development of the process is quite complex, and has a number of features that distinguish it from conventional corrosion. The nature, speed and degree of damage to the surface are strongly influenced not only by the characteristics of the aquatic environment (hydrogen index, composition and concentration of dissolved electrolytes, etc.), but also by the ability of the insulating layer to release corrosive agents – chlorides and sulfates under the influence of water.
 Chlorides and sulfates are water-soluble substances, their aqueous solutions have high electrical conductivity, which increases the corrosion intensity. Also the features of moisture accumulation of thermal insulation, which directly depends on the microstructure of the material are important.
 During operation, the outer surface of the insulated pipelines is inaccessible for visual inspection without opening the insulation, and the beginning of corrosion in this case is difficult to determine, as a result, severe corrosion may occur with subsequent loss of integrity of the pipeline wall. The aggressiveness of the environment under thermal insulation is due to several factors: high temperature, the presence of moisture and chemicals.
 The problem of metal corrosion is considered to be one of the most significant in safe operation of industrial facilities, as well as reducing the damage to the economics and the environment. Corrosion protection under thermal insulation is a serious problem requiring special attention.

Experimental study on the mechanical behavior of buried steel pipeline subjected to the local subsidence

Localized subsidence of soil layer is a typical geological disaster for buried long-distance oil and gas pipelines, which seriously threatens the safe operation of oil and gas pipelines. Therefore, a series of large-scale model tests are performed to investigate the mechanical response of the buried pipe induced by surrounding soil when the localized soil layer sinks. Results indicate that the subsidence height has a relatively greater impact on pipe strain and soil pressure than the subsidence range. Moreover, the distribution of the pipeline strain presents obvious regional characteristics and is divided into subsidence regions, non-subsidence affected regions, and non-subsidence unaffected regions. With the increasing moisture content of the backfill, the strain of the pipeline and the earth pressure around the pipe was reduced. In addition, the modified Marston earth pressure formula is proposed to estimate the vertical earth pressure on the top of the pipeline. The vertical earth pressure calculated using the proposed method fits well with the test results.