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Article

Wei Yan, Yong Xiang, Wenliang Li and Jingen Deng

This paper aims to establish the downhole CO2 partial pressure profile calculating method and then to make an economical oil country tubular goods (OCTG) anti-corrosion…

Abstract

Purpose

This paper aims to establish the downhole CO2 partial pressure profile calculating method and then to make an economical oil country tubular goods (OCTG) anti-corrosion design. CO2 partial pressure is the most important parameter to the oil and gas corrosion research for these wells which contain sweet gas of CO2. However, till now, there has not been a recognized method for calculating this important value. Especially in oil well, CO2 partial pressure calculation seems more complicated. Based on Dolton partial pressure law and oil gas separation process, CO2 partial pressure profile calculating method in oil well is proposed. A case study was presented according to the new method, and two kinds of corrosion environment were determined. An experimental research was conducted on N80, 3Cr-L80 and 13Cr-L80 material. Based on the test results, 3Cr-L80 was recommended for downhole tubing. Combined with the field application practice, 3Cr-L80 was proved as a safety and economy anti-corrosion tubing material in this oil field. A proper corrosion parameter (mainly refers to CO2 partial pressure and temperature) can ensure a safety and economy downhole tubing anti-corrosion design.

Design/methodology/approach

Based on Dolton partial pressure law and oil gas separation process, CO2 partial pressure profile calculating method in oil well is proposed. An experimental research was conducted on N80, 3Cr-L80 and 13Cr-L80 material. A field application practice was used.

Findings

It is necessary to calculate the CO2 partial pressure properly to ensure a safety and economy downhole tubing (or casing) anti-corrosion design.

Originality/value

The gas and oil separation theory and corrosion theory are combined together to give a useful method in downhole tubing anti-corrosion design method.

Details

Anti-Corrosion Methods and Materials, vol. 63 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

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Article

Zhichao Qiu, Chunming Xiong, Zhengrong Ye, Xiang Zhou, Rui Wang, Xueqiang Lin and Pengfei Sui

This paper aims to explore the influence of CO2 partial pressure, flow rate and water cut on N80 steel corrosion behaviors in the displacement process of oil in glutenite…

Abstract

Purpose

This paper aims to explore the influence of CO2 partial pressure, flow rate and water cut on N80 steel corrosion behaviors in the displacement process of oil in glutenite reservoir by CO2 injection.

Design/methodology/approach

A self-made 3 L high-temperature and high-pressure autoclave was used to conduct corrosion simulation experiments of N80 steel in different CO2 partial pressures, flow rates and water cut (the independently developed oil and water mixing approach can ensure the uniform mixing of oil and water in experiments). Techniques like weight loss and surface analysis were used to analyze the corrosion behaviors of N80 steel under different conditions.

Findings

Results showed that the average corrosion rate of N80 steel accelerated at varying degrees with the increase of CO2 partial pressure, flow rate and water cut. Excluding that the samples showed uniform corrosion under the two conditions of 0.5MPa CO2 partial pressure and static corrosion, they displayed mesa attack corrosion under other conditions. Besides, with the increase of CO2 partial pressure, the pH value of solution dropped and the matrix corrosion speed rose, hence leading to the increased Fe2+ and CO32− concentration. Meanwhile, a lowered pH value improved the FeCO3 critical supersaturation, thereby leading to an increased nucleation rate/growth rate and ultimately causing the decrease of the dimension of FeCO3 crystallites formed on the surface of the samples.

Originality/value

The results can be helpful in targeted anti-corrosion measures for CO2/oil/water corrosive environment.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

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Article

J. BROCAS, Y. CHERRUAULT, A. GUILLEZ and C. FROMAGEOT

We demonstrate an efficient numerical method for the solution of partial differential equations arising from a model suggested by BROCAS and CHERRUAULT and completed by…

Abstract

We demonstrate an efficient numerical method for the solution of partial differential equations arising from a model suggested by BROCAS and CHERRUAULT and completed by CHERRUAULT and GUILLEZ.

Details

Kybernetes, vol. 11 no. 2
Type: Research Article
ISSN: 0368-492X

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Article

Alejandro B. Engel, Eduardo Massad and Petronio Pulino

Proposes a modified Hill model for the oxyhaemoglobin dissociation curve. The model fits normal oxyhaemoglobin dissociation experimental data quite accurately, and can…

Abstract

Proposes a modified Hill model for the oxyhaemoglobin dissociation curve. The model fits normal oxyhaemoglobin dissociation experimental data quite accurately, and can easily be adapted to experimental data of subjects suffering haemoglobinopathies when available. Discusses the Adair equation, as well as correcting factors for varying temperature and pH.

Details

Kybernetes, vol. 25 no. 1
Type: Research Article
ISSN: 0368-492X

Keywords

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Article

P. Bielkowicz

WHEN the temperature of the gas reaches the high level, the molecules begin to break up into atoms or groups of atoms, which after recombination form new and smaller…

Abstract

WHEN the temperature of the gas reaches the high level, the molecules begin to break up into atoms or groups of atoms, which after recombination form new and smaller molecules of a simpler structure. For instance, tri‐atomic molecules after having been split form diatomic ones. This process is called the dissociation of gases. The newly‐formed molecules, when colliding, again form molecules of the original gas, so two processes are occurring simultaneously. However, the higher the temperature, the larger the percentage of dissociated molecules.

Details

Aircraft Engineering and Aerospace Technology, vol. 18 no. 5
Type: Research Article
ISSN: 0002-2667

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Article

Yuanpeng Cheng, Yu Bai, Zili Li and JianGuo Liu

The purpose of this paper was to investigate the corrosion behavior of X65 steel in the CO2/oil/water environment using mass loss method, potentiodynamic polarization…

Abstract

Purpose

The purpose of this paper was to investigate the corrosion behavior of X65 steel in the CO2/oil/water environment using mass loss method, potentiodynamic polarization technique and characterization of the corroded surface techniques.

Design/methodology/approach

The weight loss analysis, electrochemical study and surface investigation were carried out on X65 steel that had been immersed in the CO2/oil/water corrosive medium to understand the corrosion behavior of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of flow velocity, CO2 partial pressure and water cut on the CO2 corrosion rate of X65 steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature of 60°C and CO2 partial pressure of 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using X-ray diffraction.

Findings

The results showed that corrosion rates of X65 steel both increased at first and then decreased with the increase of flow velocity and CO2 partial pressure, and there were critical velocity and critical pressure in the simulated corrosive environment, below the critical value, the corrosion products formed on the steel surface were loose, porous and unstable, higher than the critical value, the corrosion product ?lms were dense, strong adhesion, and had a certain protective effect. Meanwhile, when the flow velocity exceeded the critical value, oil film could be adsorbed on the steel surface more evenly, corrosion reaction active points were reduced and the steel matrix was protected from being corroded and crude oil played a role of inhibitor, thus it influenced the corrosion rate. Above the critical CO2 partial pressure, the solubility of CO2 in crude oil increased, the viscosity of crude oil decreased and its fluidity became better, so that the probability of oil film adsorption increased, these factors led to the corrosion inhibition of X65 steel reinforced. The corrosion characteristics of gathering pipeline steel in the corrosive environment containing CO2 would change due to the presence of crude oil.

Originality/value

The results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO2/oil/water corrosive environment.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article

P. Bielkowicz

A GENERAL outline of the processes occurring in the working fluid of a rocket engine has been summarized previously, but the total picture is still far from complete, a…

Abstract

A GENERAL outline of the processes occurring in the working fluid of a rocket engine has been summarized previously, but the total picture is still far from complete, a number of important phenomena not having been taken into account. Their full analysis would be, however, beyond the scope of this paper, and may be left to specialists more qualified than the author to give an account of combustion processes.

Details

Aircraft Engineering and Aerospace Technology, vol. 19 no. 1
Type: Research Article
ISSN: 0002-2667

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Article

P. Koutmos, C. Mavridis and D. Papailiou

A two dimensional time‐dependent Navier Stokes formulation that encompasses aspects from both the LES formalism and the conventional k‐ε approaches was employed to…

Abstract

A two dimensional time‐dependent Navier Stokes formulation that encompasses aspects from both the LES formalism and the conventional k‐ε approaches was employed to calculate a range of reacting bluff‐body flows exhibiting high or low level large scale structure activity. Extensive regions of local flame extinction found in these bluff‐body flame configurations were treated with a partial equilibrium/two‐scalar exponential PDF combustion submodel combined with a local extinction criterion based on a comparison of the turbulent Damkohler number against the ratio of the scalar scale to the reaction zone thickness. A dual‐mode description, burning/ non‐burning, of combustion provided the local gas state. Comparisons between calculations and measurements indicated the ability of the method to capture all the experimentally observed variations in the momentum and reactive scalar mixing fields over a range of operating conditions from the lean to the rich blow‐out limit.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 9 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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Article

P. Palanisamy and D.H.R. Sarma

A major drawback of current copper thick‐film technology is the inefficient removal of the organic binder associated with the dielectric material in the low‐oxygen inert…

Abstract

A major drawback of current copper thick‐film technology is the inefficient removal of the organic binder associated with the dielectric material in the low‐oxygen inert gas (N2) atmosphere of the furnace. In processing large area and/or multilayer substrates, the incomplete binder removal causes deleterious effects which have been well documented. Therefore, it is necessary to remove hydrocarbons and residual carbon from the films in the burn‐out section of the furnace before the films begin developing their characteristic microstructures. However, the atmosphere currently employed is not capable of removing all the carbon and hydrogen in the form of gaseous oxides. In literature, in addition to furnace modifications, several atmosphere modifications and manipulations have been proposed to achieve optimum properties for the fired films. With few exceptions, the scientific basis for such atmosphere modifications and manipulations has been left either unaddressed or obscure. With this background, this paper examines the feasibility of using a reactive gas mixture in the furnace to achieve efficient organic binder removal. Phase stability diagrams are presented to illustrate the stability of (i) carbon, (ii) thick film copper ingredients, (iii) active phases of resistors, and (iv) components of glassy and crystalline phases of dielectrics in selected reactive atmospheres. The stability of certain furnace belt constituents is also addressed. Mass balance calculations are shown to demonstrate the extent of carbon removal and copper oxidation in typical nitrogen atmospheres. Based on the interpretation of thermodynamic data and reaction mechanisms involved, a specific H2‐H2O mixture with nitrogen as the carrier gas is recommended. The approach presented here constitutes a general analytical scheme to understand materials‐atmosphere interactions occurring across a temperature range. Several issues in furnace design are also discussed from the standpoint of gas‐solid reaction kinetics. These deal with the design of gas‐flow systems that facilitate removal of organic binders.

Details

Microelectronics International, vol. 4 no. 2
Type: Research Article
ISSN: 1356-5362

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Article

S. Mellul, D. Navarro and F. Rotman

This paper reports the final results of a development project conducted on nitrogen‐based atmospheres in order to improve the firing of copper thick films. Having shown…

Abstract

This paper reports the final results of a development project conducted on nitrogen‐based atmospheres in order to improve the firing of copper thick films. Having shown that improvements in copper thick film performance can be obtained under production conditions by the control and regulation of oxygen additions during the first stages of firing, the authors studied the effects on copper thick film systems of other gaseous oxidisers (CO2, N2O, H2O) injected into the nitrogen furnace atmosphere either throughout the entire furnace or into its burnout zone only. SEM examinations of the microstructures of copper films, correlated with properties such as adhesion, solderability and resistivity, allow ideal firing atmosphere conditions for copper thick film manufacturing to be determined: it is necessary to restrict atmosphere doping to the burnout zone; oxygen and water vapour are the most effective gaseous dopants. Some specific equipments have been developed for controlling the injection of these dopants into the furnace atmosphere.

Details

Microelectronics International, vol. 9 no. 1
Type: Research Article
ISSN: 1356-5362

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