Transport Of Hydrocarbons Research Articles

Spontaneous Lifting and Self-Cleaning of Gas Hydrate Crystals.

Crystal fouling, which refers to the accumulation of precipitates on surfaces and the associated damage, is a common problem in many industrial processes. In deepwater oil and gas transportation, hydrate blockage poses as a considerable barrier. Consequently, modifying hydrophobicity of surfaces has become an increasingly focused strategy to mitigate hydrate. However, the design of surfaces that effectively control the hydrate remains challenging. Herein, we report a superior smooth anti-hydrate material based on silanized modification. The low-adhesion silanized silicon wafer (SSW) realizes a win-win strategy of hard formation and easy removal. Through a comprehensive study combining experimental validation with theoretical analysis, the unique characteristics of SSW in the field of anti-hydrate surfaces were deeply discussed. Various hydrate crystals exhibited a completely different hydrate growth mode at the SSW surface, in which hydrate crystals spontaneously elevated and lifted themselves off from the surface. The presence of the fluorine element on the SSW surface allowed self-lifting growth of hydrate crystals after they covered the water droplet. And the loose and porous crystal structure in this self-lifting growth could reduce the contact area between the hydrate crystals and the substrate, allowing the crystals with minimal adhesion force and removal disturbance. Furthermore, the gas enrichment on the SSW surface also reduced the contact with the substrate, thereby decreasing the adhesion and allowing self-cleaning behavior. These results indicate that the silanized surface is a promising candidate for developing anti-hydrate materials for hydrocarbon production and transportation industry.

Computational modeling of localized corrosion in steel pipelines supported by composite sleeves

Pitting corrosion is a worrying phenomenon in the oil industry representing a major threat that can lead to the reduction of the structural integrity of pipeline transportation networks. To prevent this corrosion risk, active cathodic protection with a potential maintained at – 850 mV Cu/CuSO4 is used as a coating protection system based on bituminous binders to isolate the steel from the corrosive soil environment in hydrocarbon transportation pipelines. In this work, we examine the clock spring repair method by applying composite paths including a numerical simulation on corroded tubes using ANSYS software. The approach involves analyzing the structure under three scenarios: without defects, after the introduction of elliptical simulated corrosion pits, and following repair with multilayer reinforcement using a composite sleeve. The results indicate that the stress distribution varies across each scenario. In the case of a structure with parabolic corrosion defects, the Von Mises stresses are unevenly distributed. The defect exhibits a peak stress that could lead to the propagation of corrosion pits, necessitating repair. Conversely, in the scenario where the corroded structure is reinforced with a composite sleeve, the maximum Von Mises stress is decreased to levels comparable to those of an uncorroded pipe, demonstrating the necessity and effectiveness of using composite sleeve reinforcement.

Field and laboratory study on the distribution, fate and transport of polycyclic aromatic hydrocarbons in the loess porous medium at a refinery polluted site: Understanding the soil-groundwater interface

Soil and groundwater pollution from industrial and agricultural activities has become a global concern. This study therefore investigates the occurrence, sources, and transport mechanisms of polycyclic aromatic hydrocarbons (PAHs) in the soil-groundwater system of a closed refinery. Field investigations and laboratory column experiments revealed widespread PAH contamination in both groundwater and soil, with higher concentrations near the groundwater level (6.45–8.75 m). PAHs in soil and groundwater were predominantly low and medium molecular weight compounds (LMW and MMW), originated from petroleum leakage and coal combustion. The region’s soil, primarily composed of loess and gravel with low total organic carbon (TOC) content (mean 0.07 %), showed a positive correlation between PAH concentration and TOC/clay content, while sand content had no significant impact. Groundwater fluctuations influence PAH accumulation at the soil-groundwater interface (SGI), which may suggest potential for increased migration under varying hydraulic conditions. This vertical migration offers new insights into contaminant transport models in groundwater systems, particularly for arid regions, and could inform future remediation strategies for similar contamination scenarios.

Thermal conductivity measurements for n-hexane and n-heptane at elevated temperature and pressure

Thermal conductivity is a very important thermal property parameter in the process of hydrocarbons transportation, storage, combustion and cooling. Therefore, accurate thermal conductivity is important in the utilization of hydrocarbons. In this work, the thermal conductivity of n-hexane and n-heptane in the temperature range of 298.15 K∼523.15 K and pressure range of 0.1 MPa∼15.0 MPa was studied by using transient hot-wire method. In order to facilitate engineering application, function polynomials of temperature and pressure are fitted and correlated with experimental data. The average absolute error of the experimental data and fitting data of n-hexane and n-heptane are 0.72 and 0.61 %, respectively, which proves that the function polynomial can describe the experimental data well. In addition, we compare the collected literature data with our results and find that the literature data is very close to our results. This work is expected to expand the range of available data on the thermal conductivity of n-hexane and n-heptane and contribute to the industrial applications of these two substances.

An equivalent average shear stress yield criterion based on Simpson's numerical integration rule and its application in burst pressure analysis of thin-walled pipelines

Pipelines are a crucial transportation infrastructure for the long-distance transport of natural gas, oil, and other hydrocarbons, typically conducted through thin-walled pipes (D/t≥20). Accurate prediction of the burst pressure of thin-walled pipelines is essential for their safe and reliable operation. To enhance the prediction accuracy of the burst pressure for defect-free, straight, thin-walled pipes, a new numerical integration yield criterion was proposed between the Tresca and Mises criteria, using the mean value of Simpson's numerical integration (MSI) as the equivalent shear stress. A new burst pressure prediction formula was then constructed using the MSI yield criterion. The burst pressure predictions based on different yield criteria were compared with experimental data. Additionally, the burst pressure curves of the new prediction formula were plotted, and the relative errors between the new prediction formula and four existing prediction formulas were analyzed and compared. The results indicate that the new burst pressure prediction formula using the MSI yield criterion closely matches the experimental data, with the best relative error result within a confidence interval of ±1.3 %. The Lord parameter curve and plane stress curve of the MSI yield criterion exhibit good consistency with the experimental data of various ductile metal materials. The new burst pressure formula established by incorporating the MSI criterion provides a safe, economical, and reliable theoretical foundation for the design, manufacture, inspection, and safety assessment of thin-walled pipelines in production practice.

Prediction Method for the Distribution of the Effective Dominant Path of Sand Bodies Transporting Oil and Gas and Its Application

To study the oil and gas distribution law in the slope area of a hydrocarbon-bearing basin, one must first define the dominant hydrocarbon transport paths of sand bodies as the superimposed area of the contiguously distributed area of the sand bodies and the paleotectonic ridges at the top interface of the formation. Then, the oil and gas supply area of the oil source faults must be defined, as the overlapped area of the favorable transport paths of oil source faults and the width of their associated fracture zones. Stacking the two areas, we can delineate the distribution of the effective dominant paths of sand bodies transporting oil and gas. The results from our case study of the Qinan area show that the effective dominant paths of sand bodies transporting oil and gas in the lower sub-member within the first member of the Shahejie Formation (Es1L) in the Qinan area are distributed throughout the region, with better development in the west than in the east. And, the effective dominant paths in the eastern part extend from north to south, while those in the western part extend from northeast to southwest. These are favorable for the convergence of oil and gas generated from source rocks in the third member of the Shahejie Formation (Es3) in the main depression of Qikou Sag in the Es1L in the Qinan area. The results are consistent with the fact that oil and gas discovered in the Es1L in the Qinan area are mainly distributed in the central and western regions, with a small amount in the southeast. Therefore, the suggested method is feasible for predicting the effective dominant paths of sand bodies transporting oil and gas.

A Method for Predicting the Action Sites of Regional Mudstone Cap Rock Affecting the Diversion of Hydrocarbons Transported along Oil Source Faults

Regional mudstone cap rock has an important influence on the oil and gas distribution of the oil source faults below it. Therefore, studying the influence of these mudstone cap rocks on the hydrocarbon distribution pattern is fundamental to understanding the oil and gas distribution of the lower generation and upper reservoir reservoirs in the Bohai Bay Basin. This study classified two types of hydrocarbon diversion from oil source faults: blockage diversion and seepage diversion. To locate them, we established a method to predict the areas with blockage diversion and seepage diversion separately by superimposing the sealing and leakage parts of the regional mudstone cap rock with the regions of the connected distribution of sand bodies and the favorable hydrocarbon transport sites of the oil source faults, respectively. We used this approach to predict the locations where hydrocarbons are diverted by the oil source faults under the regional mudstone cap rocks in the first and second sections of the Dongying Formation (E3d1-2) in the Liuchu area of the Raoyang Sag, Bohai Bay Basin. The results show that the regional mudstone cap rock’s blockage diversion occurs mainly in the south-central area of Liuchu, with a localized distribution in the northern part. The seepage diversion site is primarily located in the northeastern area and is also found locally in the west. Both diversions are beneficial for the accumulation of hydrocarbons from the source rocks of the first member of the Shahejie Formation (E3s1) to the upper second member of the Dongying Formation (E3d2U). The latter can also accumulate hydrocarbons in the Guantao Formation (N1g). The results align with the hydrocarbon distribution, demonstrating the feasibility of our method to predict various oil source fault diversion sites under the regional mudstone cap rock. This prediction method offers valuable guidance for exploring the lower generation and upper reservoir hydrocarbon accumulations in hydrocarbon-bearing basins.

Lignin-derived compounds assisted with Kocuria marina H-2 and Pseudomonas putida B6-2 co-culture enhanced naphthalene biodegradation

The implementation of environmentally friendly and sustainable remediation strategies positively impacts solid waste management. In this study, the Kocuria marina H-2 and Pseudomonas putida B6-2 co-culture system demonstrated enhanced naphthalene biodegradation efficiency compared to single-strain cultures. Under optimal conditions of 35 °C, 200 rpm/min, and a 1:1 ratio of the co-culture system, the naphthalene biodegradation potential was further increased. Notably, the addition of both ethylenediamine-pretreated lignin and p-hydroxybenzoic acid significantly elevated naphthalene degradation rates to 68.5 %. In addition, the oil-liquid surface tension decreased, while cell surface hydrophobicity and colony-forming units increased with the addition of lignin-derived compounds. The modification of naphthalene bioavailability by ethylenediamine-pretreated lignin would accelerate the uptake and transport of hydrocarbons via ABC transporters and flagellar assembly. Importantly, genes related to bacterial chemotaxis and fatty acid biosynthesis were upregulated during the co-metabolism of naphthalene and p-hydroxybenzoic acid, further enhancing naphthalene bioconversion.

Monitoring and optimising hydro-carbon transport in Burkina Faso: The expériences of total energies Marketing Burkina

Monitoring and optimising hydro-carbon transport in Burkina Faso: The expériences of total energies Marketing Burkina

The ATP-binding cassette transporter subfamily G member 4 mediates cuticular hydrocarbon transport to regulate drought tolerance in Acyrthosiphon pisum

ABC transporters are a highly conserved membrane protein class that promote the transport of substances across membranes. Under drought conditions, insects primarily regulate the content of cuticular hydrocarbon (CHC) to retain water and prevent evaporative loss. Involvement of ABC transporter protein G (ABCG) subfamily genes in insect CHC transport has been relatively understudied. In this study, we demonstrated that ABCG4 gene in Acyrthosiphon pisum (ApABCG4) is involved in CHC transport and affects drought tolerance by regulating CHC accumulation. ApABCG4 is strongly expressed in the abdominal cuticle and embryonic stages of A. pisum. Effective silencing of ApABCG4 was achieved using RNAi, and the silencing duration was analyzed. ApABCG4 silencing resulted in a significant decrease in the total and component contents of the CHC and cuticular waxy coatings of A. pisum. Nevertheless, the internal hydrocarbon content remained unchanged. The lack of cuticular hydrocarbons significantly reduced the drought tolerance of A. pisum, shortening its survival time under drought stress. Drought stress caused significant upregulation of ApABCG4. Molecular docking showed that ApABCG4 has a high binding affinity for nine n-alkanes of CHC through electrostatic interactions. These results indicate that ApABCG4 is a novel RNAi target with key applications in aphid biological control.

The kinetics of droplet wetting gas hydrate surfaces regulated by anti-agglomerant monolayers: Insights from molecular dynamics study

Anti-agglomerants (AAs) have become a promising strategy for mitigating gas hydrate risks in hydrocarbon transport systems. However, a notable limitation of AAs is their diminished effectiveness in systems with high water content. The density of the AA monolayer is a critical factor influencing the coalescence and agglomeration of hydrate particles with water droplets, but the mechanisms driving these effects remain largely unknown. In this study, molecular dynamics (MD) simulations were employed to explore the anti-wetting performance and interaction properties of Cocamide Monoethanolamine (CMEA) monolayers at varying densities on hydrate surfaces. The results indicate that in systems with low-density monolayers, CMEA molecules exhibit high degrees of freedom and increased fluctuation frequencies, allowing the water molecules of droplet to penetrate the monolayer and rapidly wet the hydrate surface. In contrast, high-density monolayer configurations show properties that hinder droplet wetting on hydrate surfaces and inhibit hydrate growth. Further investigation into the adsorption behavior of CMEA molecules on hydrate surfaces highlights the substantial impact of the solution phase on adsorption free energy, with gas-phase environments enhancing the binding strength between CMEA molecules and hydrate surfaces. These molecular insights offer valuable observations regarding the structural adaptability of AA monolayers during droplet permeation and wetting processes, providing critical information for understanding the broader interactions between anti-agglomerant molecules and hydrates.

Long-Range Transport of Polycyclic Aromatic Hydrocarbons and Metals in High Altitude Lacustrine Environments of the Eastern Himalayas: Speciation, and Source Apportionment Perspectives

Long-Range Transport of Polycyclic Aromatic Hydrocarbons and Metals in High Altitude Lacustrine Environments of the Eastern Himalayas: Speciation, and Source Apportionment Perspectives

Moving horizon estimation for pipeline leak detection, localization, and constrained size estimation

Advanced pipeline leak detection and localization techniques are needed to reduce greenhouse gas emissions from hydrocarbon transportation pipelines. Developing effective leak detection and localization methods is challenging due to the spatiotemporal dynamics of process variables, the presence of process/measurement disturbances and constraints, and the limited measurement data. To address this issue, this manuscript proposes a novel moving horizon estimation design for pipeline leak detection, constrained estimation of leak size and location by using an infinite-dimensional pipeline hydraulic model. Based on the mass and momentum balance laws and the Cayley–Tustin time-discretization method, an infinite-dimensional discrete-time pipeline hydraulic model is proposed considering (unknown but bounded) disturbance and leak. By introducing a coordinate transformation, we decouple the leak size and location estimation problems. The implementable discrete-time moving horizon estimator and observer are designed for constrained leak size and location estimation. The effectiveness of the proposed designs is validated via simulation examples.

Diagnostics of velocity-flow characteristics in laminar flows

Understanding and evaluating various types of fluid movement is important for the analysis and design of systems and devices related to hydraulics and hydrodynamics, including hydrocarbon production and transport systems. Knowledge of stationary and non-stationary types of motion makes it possible to predict and control the behavior of a fluid under various conditions. The article discussed the issues of diagnosing stationary and non-stationary and gravitational flows. It has been established that the time of transition to a stationary mode in pipelines mainly depends on the geometric parameters of the pipeline and the rheological properties of the pumped systems. It is known that many issues related to the management of technological processes and the improvement of efficiency in oil and gas production are closely associated with the movement of homogeneous and heterogeneous fluids with various rheological and physico-chemical properties in pipelines during extraction, collection, and transportation, which have different forms and hydraulic characteristics. In the laminar flow regime, a methodology has been developed to determine the transition time to a steady-state operation mode, based on the flow characteristics of viscous and visco-plastic fluids, taking into account inertia forces. It has been determined that, unlike viscous fluids, the time to reach a steady-state operation mode for visco-plastic flows also varies depending on the formation of the flow core, which is determined by the initial yield stress. In the article, a mathematical expression is provided for determining the flow rate for visco-plastic fluids in laminar flow, taking into account the pressure losses due to inertia forces for viscous fluids. The results obtained are explained to eliminate the difference and increase accuracy when determining the flow rate using the Poiseuille formula for visco-plastic laminar flows.

Identification and tracing of near-source petroleum transport system based on reservoir bitumen index (RBI) method: A case study of the lower cambrian in the Tazhong-Bachu area, Tarim Basin, China

The exploration of deep layers has become increasingly important in the global oil and gas industry. The Tazhong-Bachu area of the Tarim Basin is a pioneering target for deep petroleum exploration in China, but only Wells Zhongshen1 and Zhongshen5 have found industrial oil flow in the Cambrian. Noteworthily, the occurrence of reservoir bitumen in the Lower Cambrian coring interval in many wells indicates that large-scale hydrocarbon migration had occurred here in geological history. Effective identification of reservoir bitumen in the Cambrian dolomite reservoirs is crucial to understanding hydrocarbons' distribution and migration. In this study, we adopt the Reservoir Bitumen Index (RBI) method to deduce a quantitative calculation formula for reservoir bitumen, and classify the transport system into four types based on differences in hydrocarbon transport behavior and characteristics. The results show that the deep carbonate low permeability-tight reservoirs of the Lower Cambrian in the Tazhong-Bachu area generally develop reservoir bitumen, most likely derived from underlying Precambrian source rocks. Therefore, the Lower Cambrian carbonate reservoir is considered a near-source discrete petroleum transport system, providing great potential for further oil and gas exploration in the Lower Paleozoic in the Tazhong-Bachu area.

Creation of a complex multivariate integrated model of the oil interfield transport system

Background. In conditions of variability of external and internal factors that directly affect the loading of the existing hydrocarbon transport system, the risks arise associated with the productive capacity of the existing infrastructure and noncompliance with the requirements for the quality of delivered oil. Objective. To create a tool allowing to assess the degree of loading of existing infrastructure facilities and indicators of the commercial quality of oil at commercial delivery sites in the near and long term, the availability of which is essential for risk minimization. Materials and methods. An integrated model in combination with automation tools is an effective tool for making strategic decisions in order to develop the assets of a subsurface user company. Results. By the example of transport infrastructure, the paper describes an approach to using the gathering system model, which jointly with automation algorithms allows solving a number of strategic tasks of oil and gas producers, such as performing multivariate hydraulic calculations and monitoring oil quality in order to verify compliance with the requirements. Conclusions. An integrated model in combination with the developed automation tools is an auxiliary tool for management decision-making. The tool helps to significantly reduce the labor costs for performing calculations and primary processing of the results. The implemented approaches can be used for hydraulic calculations and monitoring of limitations of transportation networks of similar configuration.

Single and multiphase flow leak detection in onshore/offshore pipelines and subsurface sequestration sites: An overview

Leaks may occur in existing pipelines, even when designed with quality construction and appropriate regulations. The economic impact of oil spills and natural gas dispersion from leaks can be huge. Failure to detect pipeline leaks promptly will have an adverse impact on life, the economy, the environment, and corporate reputation. Therefore, early detection of leaks, their location, and their size with high sensitivity and reliability are important for efficient hydrocarbon transportation through a pipeline, both in onshore and offshore applications. Although several studies have been conducted on leak detection using various techniques, recent literature that comprehensively investigates and summarizes the different multiphase leak detection techniques could not be found. Therefore, this paper provides a comprehensive review of the different leak detection techniques in pipelines, wellbores, and subsurface sequestration wells. This is done by studying the different multiphase flow leak detection techniques using various Computational Fluid Dynamics (CFD), Mechanistic, Machine Learning models, and digital twin techniques in the pipeline as well as in sub-surface sequestration sites. A comprehensive investigation revealed that a few studies have been conducted related to integrated multiphase flow leak experiments, computational fluid dynamics, mechanistic models, and implementing extended real-time transient monitoring using machine learning. This type of systematic investigation is deemed to be more useful for field applications. Furthermore, a new set of recommendations is provided in the last section which shows how experimental, mechanistic, and CFD simulation data can be used to drive a statistical approach based on modern deep learning and digital twin techniques. This allows for the precise understanding of the leak events such as size, location, and orientation of the leak, without sending a remotely operated underwater vehicle or aircraft to scan the whole pipeline and ocean.

Influence of input variables on the unitary deformation experienced in pipes subjected to the action of lateral loads

The hydrocarbon transportation industry uses extensive pipeline networks subject to complex loading conditions. The finite element analysis (FEA) has proven to be effective in simulating the deformation behavior in these pipelines, which assists in the assessment of their integrity and risks. In this work, a model developed using finite elements is proposed to analyze the behavior of API 5L Gr B carbon steel pipes, subject to internal pressure and lateral loads. The model is validated through uniaxial tensile and four-point bending tests. In addition, parametric analysis is carried out considering variables such as diameter, lateral load, and distance between supports. The objective is to identify which one of these variables has the most influence in the unit strain. The results indicate that the unit strain obtained from the numerical model agrees with the experimental tests. Furthermore, it is concluded that the diameter is the influential parameter.

Diagnostics of stationary regime in oil pipelines

Information on the evaluation of different modes of movement of liquids in pipelines is very important for the analysis and design of systems and facilities related to hydraulics and hydrodynamics, including hydrocarbon production and transportation systems. Knowledge of stationary and non-stationary types of motion makes it possible to predict and control the behavior of a fluid under various conditions. The paper discusses the issues of diagnosing stationary and non-stationary operating modes for horizontal and gravitational flows. It has been established that the time of transition to stationary mode in pipelines mainly depends on the geometric parameters of the pipeline and the rheological properties of the pumped systems.

Hydrocarbon Transportation in Heterogeneous Shale Pores by Molecular Dynamic Simulation.

Shale oil in China is widely distributed and has enormous resource potential. The pores of shale are at the nanoscale, and traditional research methods encounter difficulty in accurately describing the fluid flow mechanism, which has become a bottleneck restricting the industrial development of shale oil in China. To clarify the distribution and migration laws of fluid microstructure in shale nanopores, we constructed a heterogeneous inorganic composite shale model and explored the fluid behavior in different regions of heterogeneous surfaces. The results revealed the adsorption capacity for alkanes in the quartz region was stronger than that in the illite region. When the aperture was small, solid-liquid interactions dominated; as the aperture increased, the bulk fluid achieved a more uniform and higher flow rate. Under conditions of small aperture/low temperature/low pressure gradient, the quartz region maintained a negative slip boundary. Illite was more hydrophilic than quartz; when the water content was low, water molecules formed a "liquid film" on the illite surface, and the oil flux percentages in the illite and quartz regions were 87% and 99%, respectively. At 50% water content, the adsorbed water in the illite region reached saturation, the quartz region remained unsaturated, and the difference in the oil flux percentage of the two regions decreased. At 70% water content, the adsorbed water in the two regions reached a fully saturated state, and a layered structure of "water-two-phase region-water" was formed in the heterogeneous nanopore. This study is of great significance for understanding the occurrence characteristics and flow mechanism of shale oil within inorganic nanopores.