Phase Behaviour Analysis of the Water from Natural Gas Along the Pipelines

2017 ◽  
Vol 68 (5) ◽  
pp. 970-973
Author(s):  
Cristian Eparu ◽  
Sorin Neacsu ◽  
Eugen Mihail Ionescu ◽  
Mihai Albulescu ◽  
Alina Prundurel
Keyword(s):  
Natural Gas ◽  
Phase Behavior ◽  
Measured Data ◽  
Phase Behaviour ◽  
Water Phase ◽  
Equilibrium Conditions ◽  
Behaviour Analysis ◽  
Transmission Parameters ◽  
Wet Gas ◽  
Vapor Equilibrium

Based on the methodology for determining the liquid-vapor equilibrium conditions for wet gas, the paper presents a model of water phase behavior for the water existing in gas transmitted through pipelines, model based on Simone simulator. By using this model, we tried to correlate the measured data of humidity with the values of gas transmission parameters and with the pipeline profile.

Methods for Determining the Amount of Hydrates Formed During Blowdown of Natural Gas Compressor Station

2014 ◽  
Author(s):  
Y. Beauregard ◽  
K. K. Botros
Keyword(s):  
Natural Gas ◽  
Temperature Drop ◽  
Measured Data ◽  
Compressor Station ◽  
Case Scenario ◽  
Equilibrium Conditions ◽  
Worst Case ◽  
Moisture Contents ◽  
Natural Gas Hydrates ◽  
Allowable Range

Natural gas hydrates could form during blowdown of compressor station yard piping, even if the moisture composition is within the allowable range of up to 65 mg/st.m3. This is because the temperature of the gas drops well below the vapour-hydrate equilibrium. If sufficient hydrates form, they have the potential to impede the path of the gas to the blowdown stack exit. To evaluate this risk, it is important to determine the conditions at which hydrates could form under gas blowdown situations and accurately determine the quantity that would form as both gas pressure and temperature drop during the blowdown process. This paper first compares the hydrate equilibrium conditions for different moisture contents obtained with a publicly available model to published measured data for some alkanes present in natural gas. A gas blowdown scenario establishing the gas conditions (P and T) is then presented based on the worst case scenario of adiabatic expansion of the gas. Based on these conditions, two methods are developed to quantify the amount of hydrates that could form during the blowdown process. These methods are demonstrated on a gas blowdown event of compressor station discharge yard piping where the gas was assumed to have moisture contents of 65 mg/st.m3. The potential amount of hydrates formed and the implications on the gas path to blowdown exit are discussed.

PHASE BEHAVIOR OF WATER FROM NATURAL GAS

2018 ◽  
Vol 17 (12) ◽  
pp. 2889-2894 ◽  
Author(s):  
Cristian Eparu ◽  
Sorin Neacsu ◽  
Alina Prundurel
Keyword(s):  
Natural Gas ◽  
Phase Behavior

Pressure Prediction in Natural Gas Desulfurization Process Based on PCA and SVR

2014 ◽  
Vol 962-965 ◽  
pp. 564-569 ◽  
Author(s):  
Yan Chao Shao ◽  
Liang Jun Xu ◽  
Yan Zhu Hu ◽  
Xin Bo Ai
Keyword(s):  
Natural Gas ◽  
Prediction Model ◽  
Measured Data ◽  
Support Vector ◽  
Trend Prediction ◽  
Generalization Ability ◽  
Model Based ◽  
Scada System ◽  
Desulfurization Process ◽  
Natural Gas Desulfurization

Pressure monitoring is an important means to reflect the running status of the natural gas desulphurization process. By using the data mining technology, the interaction relationships between the pressure and other monitoring parameters are analyzed in this paper. A pressure trend prediction model is established to show the pressure status in the natural gas desulfurization process. Firstly, the theory of Principal Component Analysis (PCA) is used to reduce the dimensions of measured data from traditional Supervisory Control and Data Acquisition (SCADA) system. Secondly the principal components are taken as input data into the pressure trend prediction model based on multiple regression theory of Support Vector Regression (SVR). Finally the accuracy and the generalization ability of the model are tested by the measured data obtained from SCADA system. Compared with other prediction models, pressure trend prediction model based on PCA and SVR gets smaller MSE and higher correlation. The pressure trend prediction model gets better generalization ability and stronger robustness, and is an effective complement to SCADA system in the natural gas desulphurization process.

A Modified HLD-NAC Equation of State To Predict Alkali/Surfactant/Oil/Brine Phase Behavior

SPE Journal ◽  
2018 ◽  
Vol 23 (02) ◽  
pp. 550-566 ◽  
Author(s):  
Soumyadeep Ghosh ◽  
Russell T. Johns
Keyword(s):  
Equation Of State ◽  
Phase Behavior ◽  
Oil Recovery ◽  
Naphthenic Acids ◽  
Phase Region ◽  
Measured Data ◽  
Synthetic Surfactant ◽  
Chemical Flooding ◽  
Mineral Surfaces ◽  
Dimensionless Equation

Summary Reservoir crudes often contain acidic components (primarily naphthenic acids), which undergo neutralization to form soaps in the presence of alkali. The generated soaps perform synergistically with injected synthetic surfactants to mobilize waterflood residual oil in what is termed alkali/surfactant/polymer (ASP) flooding. The two main advantages of using alkali in enhanced oil recovery (EOR) are to lower cost by injecting a lesser amount of expensive synthetic surfactant and to reduce adsorption of the surfactant on the mineral surfaces. The addition of alkali, however, complicates the measurement and prediction of the microemulsion phase behavior that forms with acidic crudes. For a robust chemical-flood design, a comprehensive understanding of the microemulsion phase behavior in such processes is critical. Chemical-flooding simulators currently use Hand's method to fit a limited amount of measured data, but that approach likely does not adequately predict the phase behavior outside the range of the measured data. In this paper, we present a novel and practical alternative. In this paper, we extend a dimensionless equation of state (EOS) (Ghosh and Johns 2016b) to model ASP phase behavior for potential use in reservoir simulators. We use an empirical equation to calculate the acid-distribution coefficient from the molecular structure of the soap. Key phase-behavior parameters such as optimum salinities and optimum solubilization ratios are calculated from soap-mole-fraction-weighted equations. The model is tuned to data from phase-behavior experiments with real crudes to demonstrate the procedure. We also examine the ability of the new model to predict fish plots and activity charts that show the evolution of the three-phase region. The predictions of the model are in good agreement with measured data.

Under Pressure Operations on Dense Phase CO2 Pipelines: Issues for the Operator

2014 ◽  
Author(s):  
Julian Barnett ◽  
Richard Wilkinson ◽  
Alan Kirkham ◽  
Keith Armstrong
Keyword(s):  
Natural Gas ◽  
Flow Velocity ◽  
Wall Thickness ◽  
Gaseous Phase ◽  
Operating Conditions ◽  
Cooling Time ◽  
Phase Behaviour ◽  
Pipeline System ◽  
Dense Phase ◽  
Pressure Welding

National Grid, in the United Kingdom (UK), has extensive experience in the management and execution of under pressure operations on its natural gas pipelines. These under pressure operations include welding, ‘hot tap’ and ‘stopple’ operations, and the installation of sleeve repairs. National Grid Carbon is pursuing plans to develop a pipeline network in the Humber and North Yorkshire areas of the UK to transport dense phase Carbon Dioxide (CO2) from major industrial emitters in the area to saline aquifers off the Yorkshire coast. One of the issues that needed to be resolved is the requirement to modify and/or repair dense phase CO2 pipeline system. Existing under pressure experience and procedures for natural gas systems have been proven to be applicable for gaseous phase CO2 pipelines; however, dense phase CO2 pipeline systems require further consideration due to their higher pressures and different phase behaviour. Consequently, there is a need to develop procedures and define requirements for dense phase CO2 pipelines. This development required an experimental programme of under pressure welding trials using a flow loop to simulate real dense phase CO2 pipeline operating conditions. This paper describes the experiments which involved: • Heat decay trials which demonstrated that the practical limitation for under pressure welding on dense phase CO2 systems will be maintaining a sufficient level of heat to achieve the cooling time from 250 °C to 150 °C (T250–150) above the generally accepted 40 second limit. • A successful welding qualification trial with a welded full encirclement split sleeve arrangement. The work found that for the same pipe wall thickness, flow velocity and pressure, dense phase CO2 has the fastest cooling time when compared with gaseous phase CO2 and natural gas. The major practical conclusion of the study is that for dense phase CO2 pipelines with a wall thickness of 19.0 mm or above, safe and practical under pressure welding is possible in accordance with the existing National Grid specification (i.e. T/SP/P/9) up to a flow velocity of around 0.9 m/s. The paper also outlines the work conducted into the use of the Manual Phased Array (MPA) inspection technique on under pressure welding applications. Finally, the paper identifies and considers the additional development work needed to ensure that a comprehensive suite of under pressure operations and procedures are available for the pipeline operator.

scholarly journals A Graphical Alternating Conditional Expectation to Predict Hydrate Phase Equilibrium Conditions for Sweet and Sour Natural Gases

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Hai-Quan Zhong ◽  
Qi-Long Yao ◽  
Yu Wang ◽  
Yu-Fa He ◽  
Zi-Han Li
Keyword(s):  
Phase Equilibrium ◽  
Natural Gas ◽  
Hydrate Formation ◽  
Equilibrium Conditions ◽  
Natural Gases ◽  
Alternating Conditional Expectation ◽  
Hydrate Phase ◽  
Ace Model ◽  
Data Points ◽  
Formation Phase

Natural gas hydrate has been widely of concern due to its great potential in application to address problems including gas storage, transmission, separation techniques, and also as energy resource. Accurate prediction of hydrate formation phase equilibrium conditions is essential for the optimized design during natural gas production, processing, and transportation. In this study, a novel graphical alternating conditional expectation (ACE) algorithm was proposed to predict hydrate formation phase equilibrium conditions for sweet and sour natural gases. The accuracy and performance of the presented ACE model were evaluated using 1055 data points (688, 249, and 118 data points for sweet natural gas, CO2-CH4, and H2S-CO2-CH4 systems, respectively) collected from literature. Meanwhile, a comparative study was conducted between the ACE model and commonly used correlations, including thirteen models for sweet natural gases, three models for CO2-CH4 binary system, and seven thermodynamic models for H2S-CO2-CH4 ternary system. The obtained results indicated that the proposed ACE model produces the best results in prediction of hydrate phase equilibrium temperature for sweet natural gases and pressure for CO2-CH4 system with average absolute relative deviation (AARD) of 0.134% and 2.75%, respectively. The proposed quick and explicit ACE model also provides a better performance in prediction of hydrate phase equilibrium pressure for H2S-CO2-CH4 ternary systems with AARD=5.20% compared with seven thermodynamic methods considered in this work, except for CPA/Electrolyte/Chen–Guo combined model (AARD=4.45%).

Self-assembly of highly asymmetric, poly(ionic liquid)-rich diblock copolymers and the effects of simple structural modification on phase behaviour

2019 ◽  
Vol 10 (6) ◽  
pp. 751-765 ◽  
Author(s):  
Alyssa W. May ◽  
Zhangxing Shi ◽  
Dilanji B. Wijayasekara ◽  
Douglas L. Gin ◽  
Travis S. Bailey
Keyword(s):  
Ionic Liquid ◽  
Phase Behavior ◽  
Self Assembly ◽  
Structural Modification ◽  
Diblock Copolymers ◽  
Alkyl Substituent ◽  
Phase Behaviour ◽  
Phase Boundaries ◽  
Poly Ionic Liquid

A series of ATRP-synthesized poly(IL) diblock copolymers exhibit morphological phase behavior with shifted phase boundaries and alkyl substituent dependent segregation.

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