Oil Transportation System Research Articles

Numerical Investigation of Erosion in Pipeline Bends Using CFD Simulation

Erosion in pipeline bends is a significant issue in various industrial applications, particularly in oil and gas transportation systems. This study presents a numerical investigation of erosion in pipeline bends using Computational Fluid Dynamics (CFD) simulation. The primary focus is to predict erosion rates and identify erosion-prone areas based on different flow conditions, particle properties, and bend geometries. A multiphase flow model incorporating Eulerian-Lagrangian approaches was used to simulate the interaction between fluid and solid particles. The erosion rates were evaluated using empirical models that relate particle impact characteristics, such as velocity and angle of impingement, to material degradation. Simulations were conducted for various particle sizes, velocities, and flow rates, allowing for a comprehensive analysis of erosion patterns. Results indicate that erosion is concentrated on the outer walls of the bend, with higher particle velocities exacerbating material wear. Additionally, increasing particle size and flow velocity significantly influence the erosion rates. The findings of this study provide valuable insights into optimizing pipeline design and flow conditions to mitigate erosion, thereby extending the lifespan of pipeline systems in industrial applications.

The effect of subcooling on hydrate generation and solid deposition with two-phase flow of pure water and natural gases

Deepwater oil and gas transportation systems play a crucial role in energy supply, but also face the challenges of hydrate generation and blockage. The study observed hydrate generation and deposition at different subcooling degrees and flow rates by using a high-pressure fully visualized recirculation pipeline. It was found that the subcooling degree has a nonlinear positive correlation with the total amount of hydrate generated. The hydrate formation at 11.7 °C subcooling was 4.5 times higher than that at 9 °C subcooling. According to the hydrate conversion rate analysis, the hydrate growth process under low subcooling conditions directly transitions from the bubble-promoting zone to the termination point of hydrate generation. Combined with the deposition state of the pipe wall and the differential pressure change curves, the risk of blockage at different subcooling levels and flow rates can be assessed.

Analysis and optimization design of internal pressure resistance of flexible composite pipe

Flexible composite pipes have the advantages of light weight, corrosion resistance, scale resistance, and low cost compared to carbon steel pipes, and have attracted much attention in the application of onshore oil and gas gathering and transportation systems. Understanding the relationship between the pressure-bearing mechanical properties of composite pipes and their structural characteristics is crucial for guiding their process application. To investigate the mechanical behavior of flexible composite pipes under internal pressure loads, discrete and combined finite element models were established to analyze the stress-strain characteristics of flexible composite pipes. The bursting strength was predicted, and the influence of winding angle and number of reinforcement layers on the pressure-bearing capacity of flexible composite pipes was revealed. The applicability of the two models in the analysis of internal pressure resistance of flexible composite pipes was evaluated using whole pipe strain testing and instantaneous hydrostatic burst experiments. The results showed that the reinforcement layer is the main pressure-bearing layer of flexible composite pipes, and the innermost reinforcement layer bears the highest pressure. The pressure-bearing capacity of flexible composite pipes significantly increases when the winding angle is greater than 53°, and the increase in pressure-bearing capacity slows down when the number of reinforcement layers exceeds 3. Under the combination model, the strain and bursting strength of flexible composite pipes were closer to the experimental results. The study clearly defines the stress-strain characteristics of flexible composite pipes under internal pressure load and the impact of process parameters, providing a basis for the optimization design of single well oil transmission pipelines in Xinjiang oilfield.

Unveiling Turbulent Flow Dynamics in Blind-Tee Pipelines: Enhancing Fluid Mixing in Subsea Pipeline Systems

Blind tees, as important junctions, are widely used in offshore oil and gas transportation systems to improve mixing flow conditions and measurement accuracies in curved pipes. Despite the significance of blind tees, their unsteady flow characteristics and mixing mechanisms in turbulent flow regimes are not clearly established. Therefore, in this study, Unsteady Reynolds-Averaged Navier–Stokes (URANS) simulations, coupled with Explicit Algebraic Reynolds Stress Model (EARSM), are employed to explore the complex turbulent flow characteristics within blind-tee pipes. Firstly, the statistical flow features are investigated based on the time-averaged results, and the swirl dissipation analysis reveals an intense dissipative process occurring within blind tees, surpassing conventional elbows in swirling intensity. Then, the instantaneous flow characteristics are investigated through time and frequency domain analysis, uncovering the oscillatory patterns and elucidating the mechanisms behind unsteady secondary flow motions. In a 2D-length blind tee, a nondimensional dominant frequency of oscillation (Stbt = 0.0361) is identified, highlighting the significant correlation between dominant frequencies inside and downstream of the plugged section, which emphasizes the critical role of the plugged structure in these unsteady motions. Finally, a power spectra analysis is conducted to explore the influence of blind-tee structures, indicating that the blind-tee length of lbt = 2D enhances the flow-mixing conditions by amplifying the oscillation intensities of secondary flow motions.

DETERMINANTS OF EXTERNAL ECONOMIC SECURITY OF UKRAINE IN 2010-2022

Objective. The objective of the present study is to analyze the level of economic security in general and foreign economic security of Ukraine in 2010-2021, in particular, to identify disincentive factors and stimulators of foreign economic security in 2010-2022. Methods. The following methods and techniques of cognition are applied: analysis and synthesis, induction and deduction (to justify the complementary relationship between economic and foreign economic security), analysis of series of dynamics (to identify the state and trends inherent in indicators of economic and foreign economic security of Ukraine), tabular (for visual presentation of factual data on the level and dynamics of economic and foreign economic security of Ukraine in 2010-2021 and 2010-2022, respectively ). Results. On the basis of the conducted study of the level of economic security in general and external economic security of Ukraine in 2010-2021, in particular, it is determined that during the period under the analysis, the level of economic security of Ukraine was on average 40%, foreign economic security – 35%, which corresponds to a dangerous state. At the same time, foreign economic security is proposed to be considered as the state of protection of the country's national economic interests in the field of foreign economic relations, which is based on the country's ability to ensure sustainable economic growth and increase the welfare of the population in the long term; protect their national resources and markets from external threats; influence world economic processes and defend their interests in the international arena. It is identified that the factors stimulating foreign economic security of Ukraine in 2010-2022 were: high level of openness of the economy; the specifics of export-import operations – the value of exports significantly exceeded the value of imports, a high level of focus on one geographical direction was observed – one foreign trade partner, one product; low level of processing of goods and specialization in trade in raw goods with a low level of processing; low level of utilization of the transit capacities of the gas transportation and oil transportation system; sufficiently high level of import dependence; insufficient level of diversification of the economy. It is determined that despite the lack of factors stimulating the country's foreign economic security during 2010-2022, the following positive trends are observed during this period: decrease in the openness of the national economy, decrease in the level of foreign trade dependence of Ukraine on leading partner countries, decrease in the level of dependence on export volumes countries from the leading product (product group).

METHODICAL APPROACH TO EFFICIENCY ASSESSMENT OF PUMPING EQUIPMENT OF OIL PUMPING STATIONS

For the successful operation of the pumping station, including all the equipment of the oil transportation system, one of the important and key success factors is a well-organized and energy-efficient operation of pumping equipment. The costs of operating pumping equipment at oil pumping stations make up a significant part of the total cost of pumping. Therefore, there is a need to choose effective pumping equipment of oil pumping stations taking into account different criteria, which actualizes the development of a methodology for efficiency assessment of pumping equipment.The aim is to develop a methodology for efficiency assessment of pumping equipment of oil pumping stations.Objectives: to develop a system of indicators for efficiency assessment of pumping equipment; to develop methodological tools for assessing the risks of using pumping equipment; to develop a methodological approach to efficiency assessment of pumping equipment.The article uses methods of analysis and synthesis, theoretical generalizations and systematization, as well as the expert method.The analysis of scientific and technical literature in the field of efficiency assessment ofpumping equipment of oil pumping stations of the main oil pipeline for the development of methods for calculating the efficiency of pumping equipment.As a result of the study, a methodology for efficiency assessment of pumping equipment of oil pumping stations based on the construction of a loss matrix and an efficiency matrix, which allows choosing priority pumping equipment at oil pumping stations is proposed. A comprehensive indicator of the effectiveness of the use of various types of pumping equipment at oil pumping stations has been developed, taking into account the importance of the criteria for the effectiveness of pumping equipment, allowing for a comprehensive and unambiguous efficiency assessment of the use of various types of pumping equipment at oil pumping stations.An algorithm for assessing risk factors affecting pumping equipment operation, including the stages of risk identification and assessment, calculation of the integral risk level is proposed. It allows determining the risk degree of pumping equipment operation and calculating the amount of the risk premium included in the calculation of the complex indicator of the effectiveness of pumping equipment at oil pumping stations.

Safe and Secure Oil and Gas Pipeline Transportation System Based on Industrial Internet of Things

Safe and Secure Oil and Gas Pipeline Transportation System Based on Industrial Internet of Things

Numerical investigation on oil leakage and migration from the accidental hole of tank wall in oil terminal of pipeline transportation system

As a crucial component of the oil transportation system, the oil terminal (or oil tank farm) may often pose some serious threats and damage to the ecological environment and production safety for the oil leakage. An effective emergency management strategy is particularly significant, involving the accurate assessment of leakage time, oil migration path, volume distribution, etc. Therefore, the volume of fluid (VOF) and liquid phase leakage model were applied to investigate the migration and distribution characteristic after the accidental hole occurs in the tank wall, and influence factors including height and diameter of the hole were considered in our study. Results show that the lower the leaking hole position is, the faster the horizontal injection rate of the leakage hole, the increase of the accumulation area of the oil on the ground, and the difference in the overall pressure value at the leakage hole is nearly four times. Under different leakage diameters, the oil spill is symmetrical. The larger the leakage diameter, the higher the amount of oil leakage and the initial leakage speed, the maximum speed is 1.5 times the minimum speed, causing harm to safety and environmental pollution. These results can quickly locate the leakage location of the tank and provide valuable references for emergency management of the oil pipeline transportation system.

Imbalanced data augmentation for pipeline fault diagnosis: A multi-generator switching adversarial network

Pipeline fault diagnosis is of practical necessity for the stable operation of large-scale oil and gas transportation systems. Despite the remarkable achievements of existing intelligent fault diagnosis methods, these studies have encountered noticeable performance degradation when directly applied in real industrial scenarios due to the absence of sufficient and balanced datasets. To this end, this paper proposes a novel multi-generator switching adversarial network (MGSAN) to augment the pipeline data under different health states, especially faulty ones. First, a multi-mode generator is designed to produce various candidate solutions, where a parameter-sharing scheme is employed to ensure consistency among modes at the parameter level. After that, a mode switching strategy is presented to maintain a proper tradeoff between the generator and the discriminator, which is capable of changing the state of the generator from one mode to another according to the performance (i.e., quality and diversity) of the candidate solutions. Finally, extensive experimental results on visualization and quantitative evaluation show that the MGSAN algorithm has more stable behavior and stronger exploration capabilities than well-known GAN variants. Additionally, the proposed MGSAN algorithm is successfully exploited to improve the accuracy of pipeline fault diagnosis.

A STAMP-Game model for accident analysis in oil and gas industry

Accidents in engineered systems are usually generated by complex socio-technical factors. It is beneficial to investigate the increasing complexity and coupling of these factors from the perspective of system safety. Based on system and control theories, System-Theoretic Accident Model and Processes (STAMP) is a widely recognized approach for accident analysis. In this paper, we propose a STAMP-Game model to analyze accidents in oil and gas storage and transportation systems. Stakeholders in accident analysis by STAMP can be regarded as players of a game. Game theory can, thus, be adopted in accident analysis to depict the competition and cooperation between stakeholders. Subsequently, we established a game model to study the strategies of both supervisory and supervised entities. The obtained results demonstrate that the proposed game model allows for identifying the effectiveness deficiency of the supervisory entity, and the safety and protection altitudes of the supervised entity. The STAMP-Game model can generate quantitative parameters for supporting the behavior and strategy selections of the supervisory and supervised entities. The quantitative data obtained can be used to guide the safety improvement, to reduce the costs of safety regulation violation and accident risk.

Data- and Model-Driven Crude Oil Supply Risk Assessment of China Considering Maritime Transportation Factors

Effective supply-chain risk assessment is the basis for developing sustainable supply policies, and it has received growing attention in global oil supply system management. Dynamical modeling and data-driven modeling are two main risk assessment technologies that have been applied in crude oil supply networks. Dynamical risk modeling and data-driven risk modeling offer distinct advantages in capturing the complexities and dynamics of the system. Considering their complementary strengths, a hybrid modeling framework combining system dynamics and data-driven neural networks is proposed for risk assessment of crude oil transportation network. Specifically, the system dynamics module is to capture and interpret the underlying dynamics and mechanisms of the transportation network, while the deep neural networks module is to discover the nonlinear patterns and dependencies of risk factors from various inputs. Based on joint training, the hybrid model can ultimately develop the capability of risk prediction with a small amount of data. In addition, it can consider the dynamic nature of crude oil transportation networks to interpret the predicted results of the risk level for decision-makers to make specific risk-mitigating policies. Extensive experiments based on China’s scenario have been conducted to demonstrate the effectiveness of the proposed hybrid model, and the results show that our model achieves higher accuracy in risk prediction compared to the current state of the art. The results also present an explanation for China’s policy change of building a resilient crude oil transportation system.

Simulation and experimental study on liner collapse of lined composite pipe

With the application of lined composite pipe in the offshore oil and gas transportation system, the instability and collapse problems of its liner has been paid more and more attention. In this paper, A nonlinear finite element model of elastic-plastic instability of the confined liner of lined composite pipe is established. Considering the initial out-of-roundness (δ0/R) defect, the instability configuration and displacement equilibrium path of the liner before and after critical buckling are considered, the δ0/R defect sensitivity and the relationship between D/t ratio of the liner are analyzed. Finally, the finite element solution and analytical solution are verified by experimental data in this paper and experimental data reported elsewhere. It is concluded that δ0/R defect relative to 1 % will reduce the critical instability load value by about 65 %. The relative error between finite element calculation results of instability critical load and experiment test measured load is 1.82 %. The experimental results are in good agreement with the finite element calculation results. Thus it can be seen that by using the nonlinear finite element model of elastic-plastic instability of the confined liner model established in this paper, not only the critical unstable load of the confined steel liner can be accurately solved, but also the cost of experiment test can be greatly saved. It provides a theoretical basis for the buckling-restrained design of lined composite pipe.

Properties of Salicylidene-Aniline as a Corrosion Inhibitor in Oil and Petroleum Products Transportation Systems

Introduction. Risks of accidents and fires during transportation and pumping of oil and petroleum products is a significant problem of technosphere safety. The reasons may be leaks due to corrosion damage to pipelines, tanks and oil storage tanks. In view of the possible serious financial, environmental and social consequences of such incidents, it is important to constantly seek new, more effective approaches to preventing corrosion processes. It is obvious, for example, that at present not all chemical compounds capable of suppressing or inhibiting the destruction of metals and alloys have been thoroughly studied. The presented scientific work is partly aimed at overcoming the lack of data in this area. The objective is to investigate an insufficiently studied compound salicylidene-aniline, which can be a corrosion inhibitor similar to other nitrogen-containing compounds similar in structure and composition.Materials and Methods. The gravimetric method was used to study the inhibitory, adsorption and complexing properties of salicylidene-aniline. The experiments were carried out with St3 steel plates. The mass of metal samples without an inhibitor and with an inhibitor was recorded before and after exposure in the test media. The effect was determined by the change in the corrosion rate. When setting up experiments, the authors were guided by GOST 9.905–82 "Unified system of corrosion and ageing protection. Corrosion test methods. General requirements". The volume of the corrosive medium was determined according to GOST 9.506–87 "Unified system of corrosion and ageing protection. Corrosion inhibitors of metals in water-petroleum media. Methods of protective ability evaluation". The corrosion criteria were taken from GOST 9.908–85 "Unified system of corrosion and ageing protection. Metals and alloys. Methods for determination of corrosion and corrosion resistance indices". The calculations were based on the valuation principle, which sets the ratio of a multiplicative metrized linear order on a set of particular criteria. An integral indicator based on mathematical and methodological approaches was used for ranking.Results. The effect of hydrochloric acid medium on steel samples St3 was studied. Four concentrations of the inhibitor were taken: 0 %, 0.01 %, 0.1 %, and 0.2 %. The mass of metal samples without an inhibitor and with an inhibitor was recorded before and after exposure in the test media. The effect was determined by the change in the corrosion rate. The mass index of corrosion was calculated. The surface quality during destruction and corrosion inhibition was determined in five stages: the elements to be evaluated were selected, the purpose of the evaluation was formulated, the elements of the technical condition of the object under study were found, the essence of determining the usefulness or value of the criterion was described, and the essence of optimization was explained. The studied properties were ranked with respect to the multiplicative metrized linear order on a set of particular criteria. For the calculations, the task was set — to determine the components of vector B in accordance with one of the evaluation stages. We are talking about the stage when the usefulness or value of the criterion is analyzed by points on the numerical axis indicating the state of the object "better — worse". We constructed an indicator z approximating a known or specified (learning) matrix of paired relationships between objects. The resulting indicator allowed us to assess the technical condition of the surface during the course of corrosion and when it slowed down due to the addition of salicylidene-aniline. The result was obtained for samples with a surface area from 10.1∙10-4 m2 to 11.9∙10-4 m2. During the experiment, the mass of the metal decreased by 0.2–0.8 times with the inhibitor and almost by 3.5 times without it. The mass index of corrosion was recorded from 0.15 g/m2∙h to 0.48 g/m2∙h. At the same time, the protective ability of the inhibitor was quite high: the minimum was 77.4 %, the maximum was 94.8 %. This is a convincing indicator. It is also worth mentioning such an advantage of salicylidene-aniline as a low danger. Its hazard class is III (for comparison: the hazard class of aniline is a level higher — II).Discussion and Conclusion. The authors propose to use salicylidene-aniline as a means to increase the safe service life of oil pipelines and tanks. The potential of this composition as an effective corrosion inhibitor, highly soluble in oil and petroleum products, has been proven. Such properties of salicylidene-aniline as slow oxidation and moderate toxicity are noted.

Research on a TOPSIS energy efficiency evaluation system for crude oil gathering and transportation systems based on a GA-BP neural network

As the main link of ground engineering, crude oil gathering and transportation systems require huge energy consumption and complex structures. It is necessary to establish an energy efficiency evaluation system for crude oil gathering and transportation systems and identify the energy efficiency gaps. In this paper, the energy efficiency evaluation system of the crude oil gathering and transportation system in an oilfield in western China is established. Combined with the big data analysis method, the GA-BP neural network is used to establish the energy efficiency index prediction model for crude oil gathering and transportation systems. The comprehensive energy consumption, gas consumption, power consumption, energy utilization rate, heat utilization rate, and power utilization rate of crude oil gathering and transportation systems are predicted. Considering the efficiency and unit consumption index of the crude oil gathering and transportation system, the energy efficiency evaluation system of the crude oil gathering and transportation system is established based on a game theory combined weighting method and TOPSIS evaluation method, and the subjective weight is determined by the triangular fuzzy analytic hierarchy process. The entropy weight method determines the objective weight, and the combined weight of game theory combines subjectivity with objectivity to comprehensively evaluate the comprehensive energy efficiency of crude oil gathering and transportation systems and their subsystems. Finally, the weak links in energy utilization are identified, and energy conservation and consumption reduction are improved. The above research provides technical support for the green, efficient and intelligent development of crude oil gathering and transportation systems.

Numerical simulation study on multiphase flow pattern of hydrate slurry

The research on the multiphase flow characteristics of hydrate slurry is the key to implementing the risk prevention and control technology of hydrate slurry in deep-water oil and gas mixed transportation system. This paper established a geometric model based on the high-pressure hydrate slurry experimental loop. The model was used to carry out simulation research on the flow characteristics of gas-liquid-solid three-phase flow. The specific research is as follows: Firstly, the effects of factors such as slurry flow velocity, hydrate particle density, hydrate particle size, and hydrate volume fraction on the stratified smooth flow were specifically studied. Orthogonal test obtained particle size has the most influence on the particle concentration distribution. The slurry flow velocity is gradually increased based on stratified smooth flow. Various flow patterns were observed and their characteristics were analyzed. Secondly, increasing the slurry velocity to 2 m/s could achieve the slurry flow pattern of partial hydrate in the pipeline transition from stratified smooth flow to wavy flow. When the flow rate increases to 3 m/s, a violent wave forms throughout the entire loop. Based on wave flow, as the velocity increased to 4 m/s, and the flow pattern changed to slug flow. When the particle concentration was below 10%, the increase of the concentration would aggravate the slug flow trend; if the particle concentration was above 10%, the increase of the concentration would weaken the slug flow trend, the increase of particle density and liquid viscosity would weaken the tendency of slug flow. The relationship between the pressure drop gradients of several different flow patterns is: slug flow > wave flow > stratified smooth flow.

AUTOMATED PIPELINE INSPECTION USING UNMANNED AERIAL VEHICLES

Monitoring the condition of pipelines and site facilities of the oil and gas trunk transportation system, as well as other facilities of the oil and gas complex, allows you to collect the necessary information quickly, getting into hard-to-reach places where land transport or a person cannot get to, and reduce the response time to emergency situations and eliminate their consequences.
 The paper considers the existing designs of unmanned aerial vehicles used in systems for remote monitoring of technological facilities, analyzes their advantages and disadvantages while inspecting the linear part of the trunk pipeline. Two variants for automated platforms placing along the route for taking off and recharging unmanned aerial vehicles are proposed. The first variant allows more thorough inspection while flying around, the second one allows using fewer platforms and longer inspection area.

Synthetic Data Generation Using Generative Adversarial Network for Burst Failure Risk Analysis of Oil and Gas Pipelines

Abstract Despite the pipeline network being the safest mode of oil and gas transportation systems, the pipeline failure rate has increased significantly over the last decade, particularly for aging pipelines. Predicting failure risk and prioritizing the riskiest asset from a large set of pipelines is one of the demanding tasks for the utilities. Machine learning (ML) application in pipeline failure risk prediction has recently shown promising results. However, due to safety and security concerns, obtaining sufficient operation and failure data to train ML models accurately is a significant challenge. This study employed a Generative Adversarial Network (GAN) based framework to generate synthetic pipeline data (DSyn) using a subset (70%) of experimental burst test results data (DExp) compiled from the literature to overcome the limitation of accessing operational data. The proposed framework was tested on (1) real data, and (2) combined real and generated synthetic data. The burst failure risk of corroded oil and gas pipelines was determined using probabilistic approaches, and pipelines were classified into two classes depending on their probability of failure: (1) low failure risk (Pf: 0–0.5) and (2) high failure risk (Pf: >0.5). Two random forest (RF) models (MExp and MComb) were trained using a subset of 70% of actual experimental pipeline data, (DExp) and a combination of 70% of actual experimental and 100% of synthetic data, respectively. These models were validated on the remaining subset (30%) of experimental test data. The validation results reveal that adding synthetic data can further improve the performance of the ML models. The area under the ROC Curve was found to be 0.96 and 0.99 for real model (MExp) and combined model (MComb) data, respectively. The combined model with improved performance can be used in strategic oil and gas pipeline resilience improvement planning, which sets long-term critical decisions regarding maintenance and potential replacement of pipes.

Assessment of the infiltration of water-in-oil emulsion into soil after spill incidents

The issue of inland oil spills exerts an adverse impact on environmental and ecological health. Many cases are concerned with water-in-oil emulsions, especially in the oil production and transport system. To understand the contamination and take an efficient response work after spill, this study investigated the infiltration behavior of water-in-oil emulsions and the influencing factors by measuring the characteristics of different emulsions. The results showed that an increase of water and fine particle content and decrease in temperature would improve the viscosity of emulsions and reduce the infiltration rate, whereas salinity levels had a negligible impact on infiltration if the pour point of emulsion systems was far higher than the freezing point of water droplets. It is worth mentioning that excessive water content at a high temperature may cause demulsification during the infiltration process. The oil concentration in different soil layers was related to the viscosity of emulsion and infiltration depth, and the adopted Green-Ampt model simulated well under low temperature. This study reveals the new features of emulsion infiltration behavior and distribution patterns under different conditions and is helpful for the response work after spill accidents.

Квазиведомственные нормативные правовые акты в энергетическом праве

In this article, the author reviews the existing views of legal theoreticians on internal acts of legal entities that have been lately acknowledged by legal publications as independent law sources. The paper singles out the main attribute that gives local acts of legal entities the statutory regulation quality, being the delegation of statutory regulation issuance powers to the company by the law or sanctioning by means of approval by a competent state authority. The author suggests that legal acts of legal entities issued without the delegation right or approval by the state but having statutory qualities should be reviewed on a standalone basis, as a separate law source. The article notes that a characteristic feature of such acts is their issuance by subjects of natural monopolies created as a result of market economic reforms held in Russia in the late 20th century based on branch ministries governing separate national economy sectors (electrical energy industry, gas and oil transportation system). It is the first case in legal publications when the author that makes an attempt at understanding the nature of these acts concludes that they differ from corporate and departmental acts. Due to the fact that law making by subjects of natural monopolies was actually replacing regulatory activities of ministries and other state departments, the author suggests naming the documents they issue quasi-divisional legal acts. Based on the obtained results, the author words the concept of quasi-divisional legal acts in the energy law as one of law sources.

Tapping into the potential CO2 emission reduction of a crude oil transportation system from carbon footprint perspective

With more countries adopting a net-zero carbon emission goal, low carbon has become the focus of the transformation of the petroleum industry. Improper operations of the crude oil transportation system, one of the primary energy consumers of oilfields, usually cause severe environmental problems. Following the life cycle assessment method and considering the special process characteristics of the crude oil transportation system, a detailed carbon footprint analysis was conducted from the design to the recycling phase to identify the key phase for carbon emission control. Combined with process modifications, a multi-objective operation optimization model constrained by thermal constraints and insertion oil was developed to reach economic and environmental goals. Then, the multi-objective mixed integer nonlinear programming model was turned into a mixed integer linear programming model by the piecewise linearization method and augmented ε-constraint method. The models were validated using a typical case. The carbon footprint analysis showed that the average CO2e emissions were 2.68 t CO2e/(104 km m3•a) over the lifecycle, and the CO2e emissions during the operation phase were the highest (74.04%) among all phases. Moreover, the optimization model reduced the total cost and CO2e emissions by up to 18.72% and 16.97%. Additionally, sensitivity analysis revealed that the optimal operation scheme was highly sensitive to the crude oil price and transportation volume. The total CO2e emissions per unit volume exhibited a concave trend as the transportation volume increased, indicating the existence of an optimal transportation volume that achieved the lowest emissions. The study captured the weak points of carbon emissions over the lifecycle and tapped into potential CO2 emission reduction, providing a reference for the design and operation of the future pipeline system.