bluuebunny/crossref_metadata_2025_split huggingface dataset:
Implementation of Nitrate Treatment for Reservoir Souring Control: Complexities and Pitfalls
Authors: Stott James F.D. 
Published: May 2012

Abstract
The activity of sulfate-reducing bacteria (SRB) has long been a major concern in oilfield water systems and petroleum reservoirs because these microorganisms are one of the main causative agents of microbial-influenced corrosion (MIC) as well as reservoir souring.
Calcium nitrate and sodium nitrate treatments have gained popularity in recent years as alternatives or supplements to conventional biocide treatments. The object of these nitrate treatments is the suppression of SRB activity by the selective manipulation of indigenous bacteria.
The treatments have met with mixed success; in some cases SRB activity has been suppressed, whereas in other cases the treatment has failed. Cases where nitrate treatment has not been successful are less likely to be publicized than cases where the treatment has been deemed to be successful. There are also instances where nitrate treatment has been successful in suppression of SRB activity but has given rise to unacceptable increases in corrosion rates in water injection pipe-work.
In the experience of the author, nitrate treatments are rarely planned, trialed or implemented in a systematic manner, so as to maximize the chance of success and minimize unforeseen negative consequences. Based on practical examples from the author's experience and published information, this paper examines the most important factors that should be taken into account in methodical planning of trials and field-wide implementation of nitrate treatments, with particular reference to corrosion control.
Assessment of MIC in Carbon Steel Water Injection Pipelines
Authors: Comanescu Iulian , Taxen Claes , Melchers Robert E. 
Published: May 2012

Abstract
The present study compares corrosion mass loss and pit depth measurements on carbon steel corrosion coupons exposed under similar operating parameters, but with different biological consortia. One set of data were obtained from standard flush disc corrosion coupons used to monitor corrosion rates in a water injection pipeline on the North Sea continental shelf. The coupons were exposed on average for 6 months over 6 years operational time. These data are compared with published corrosion data of coupons exposed in abiotic district hot water systems from several power plants situated in Europe. The exposure time for these coupons was 9 months. Both systems were anoxic and in the same temperature range and are comparable. Observations regarding relationship between MIC and bacterial consortia, bacterial numbers and type, water quality and corrosion products are also made.
The corrosion rate of the water injection pipeline is approximately 10 times higher compared with the corrosion rate in the abiotic district hot water system. It is concluded that the increased corrosion on the carbon steel coupons in the early stage is caused by MIC. This is also supported by the chemical and biological information available for the pipelines. The results reported here constitute the first step of an overall study to improve the level of understanding of the bacterial contribution to the total corrosion rates of carbon steel in water injection flowlines.
Such understanding is expected to improve management and operational decision-making for practical control of corrosion in the field, by providing predictions of expected life time as a function of control of biotic consortia (e.g. through pigging, and biocide treatments). Further, it will facilitate decisions concerning choice of pipeline construction materials for future design.
Influence of Brine with Different Supersaturation Ratio on Corrosion Processes for Pipeline Material Carbon Steel X65, Scale Deposition and Performance of Combined Inhibitor
Authors: Ciolkowski M. , Neville A. , Hu X. , Mavredaki E. , Sanders L. 
Published: May 2012

Abstract
Corrosion and scale deposition are well known problems in pipelines. Corrosion control of carbon steel pipelines requires an understanding of the simultaneous occurrence of both processes. To date there have been few studies demonstrating the interactions between surface scale deposition and corrosion processes. Common methods of controlling corrosion and scale are deploying corrosion and scale inhibitors. However, combined (ComI) are receiving increased attention from industry as their application can significantly reduce chemical costs. Many factors influence the performance of corrosion and scale inhibitors and the influence of supersaturated brines on the surface scale deposition and subsequent effects on corrosion processes are generally not well understood. The work presented describes a range of laboratory tests conducted to assess the influence of different supersaturated brines on corrosion and scale on both inhibited (ComI) and uninhibited systems. Corrosion is measured by conventional electrochemical techniques and surface deposition is assessed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). Bulk precipitation is measured by turbidity.
Application of Chicory as Corrosion Inhibitor for Acidic Environment
Authors: Choudhary Yogesh Kumar , Sabhapondit Anupom , Kumar Arunesh 
Published: May 2012

Abstract
During acidizing stimulation or cleanup operations, metal tubulars, downhole tools/valves, surface lines, etc. are exposed to acidic fluids and are prone to corrosion. Because corrosion rates drastically increase in high-temperature wells, controlling corrosion is critical and must be dealt with carefully. In addition, corrosion protection is important for maintaining the integrity and long life of downhole tools installed in a well. Several corrosion inhibitors, such as quaternary ammonium compounds, propargyl alcohol-based compounds, etc., have been effectively used in the industry. However, because of stringent environmental regulations, attention has focused on the development of new corrosion inhibitors that are environmentally benign. Food-grade products that are considered "green" chemicals have significant potential as corrosion inhibitors in the oil and gas industry.
In this paper, application of chicory as a corrosion inhibitor for high-temperature and strong-acidic conditions is discussed. Chicory is a perennial bush plant available in many parts of the world. The root of the chicory plant can be roasted and ground for use as a coffee substitute or additive. Chicory is environmentally acceptable and, being of plant origin, is widely recognized as biodegradable in nature. This study shows that chicory can provide corrosion protection for alloys, such as N-80, 13Cr-L80, and 1010 steel, in the presence of either inorganic or organic acids at temperatures up to 250°F (121°C). Considering its good performance, low price, and no toxicity issues, chicory has significant potential for acid corrosion-inhibition applications. The mixing procedure for preparing the blend, experimental setup and test procedure, and laboratory results of high-pressure/high-temperature (HP/HT) corrosion tests are discussed.
Corrosion Inhibition Workflow Allows Injection of High-Volume Acid Treatments through Coiled Tubing Strings in Offshore Mexico
Authors: Martin Frederic , Miquilena Emilio , Molero Nestor , Acevo Ana Karina , Franco Ernesto , Garcia Martin Garcia , Castillo Marco 
Published: May 2012

Abstract
Since 2003, the main challenge of selective matrix treatments with coiled tubing (CT) has been to manage the severe corrosion rates of CT strings with large acid volumes and long exposure times to hydrochloric acid (HCl), resulting in reduced pipe life. Generally, the average volume required per job is 300 bbl of 15% to 20% HCl, depending on the bottomhole conditions and damage mechanisms; severe material losses of carbon steel coiled tubing string grade 90,000 psi have been regularly measured above 0.20 lb/ft2.
Our local stimulation team has developed an engineering workflow that consists of several stages and can reduce corrosion rates below 0.05 lb/ft2. A laboratory database was built to perform corrosion tests under time and temperature conditions and evaluate available corrosion inhibitors. The database allows the selection of the inhibitor and concentration range for each application. To reinforce the quality control, field preparation of acids is monitored and samples are tested to compare with laboratory design. Finally, measurements of coiled tubing wall thickness give an estimated value of material weight loss.
As a result of the implementation of the workflow, average pipe life has been extended from 1,200 to 3,000 bbl of 15% HCl pumped.
External Localised Corrosion of Offshore Topside Riser System
Authors: Anunobi Kingsley 
Published: May 2012

Abstract
Offshore risers are major assets for oil & gas operator as they represent a significant part of the cost of any offshore project and are relied to transport produced fluids. Furthermore, they represent major Health, Safety, or environmental threats to populations or the environment, if any significant leak or rupture occurs. Therefore any company operating hydrocarbon risers is required to implement rigorous external corrosion management strategy.
For an offshore riser installation, life cycle Riser Integrity Management is essential at design concept, FEED, detailed design, fabrication/construction, execution, commissioning, and operations to ensure the asset is fit for service throughout its service life. Riser external corrosion management is an important aspect of the overall riser integrity management during operation which includes operation preparation, inspection, maintenance and repair. In-service riser external corrosion inspections are to be planned to identify the actual conditions of risers for the purpose of integrity assessment to ensure structural reliability. The benefit of planning and executing maintenance and inspection activities simultaneously cannot be over emphasized.
This paper will describe some specific external localized corrosion issues frequently enencountered in the offshore oil and gas riser systems. The integrity implications and recommendations for addressing these issues both at the concept selection and Front End Engineering Design (FEED) stage as well as during in-service. The paper will also highlight the major benefit of using the correct mix of inspection techiques or tool based on the prior knowledge of the associated corrosion damage mechanisms and the benefit of an optimized preventive and corrective maintenance strategy in the overall life cycle Riser Integrity Management.
Acid Corrosion Inhibitors with Improved Environmental Profiles
Authors: Sitz Curtis , Frenier Wayne , Vallejo Connie 
Published: May 2012

Abstract
This paper discusses our successful efforts in developing new all oxygen based acid corrosion inhibitors that are biodegradable, non-bioaccumulating and low in toxicity, that meet industry standards for protection of carbon steel oilfield tubing up to 120°C (~250°F). These are environmentally acceptable inhibitors with the appropriate dispersibility and performance characteristics needed for critical applications in environmentally sensitive areas.
Matrix acidizing treatments are employed to remove reservoir damage by introducing acidic solutions (usually hydrochloric acid, HCl) into the formation at pressures below those used in fracturing operations. HCl is also used in acid fracturing as an alternative to proppant fracturing. The use of HCl requires that an effective acid corrosion inhibitor be included in the treatment package to protect the well's hardware.
Quaternary amines, including pyridine and quinoline quats, are frequently used as the active components in many corrosion inhibitors. While possessing excellent inhibition properties, the compounds are toxic to many forms of sea life, as well as to humans. Quats have been the backbone of the HCl acid corrosion control efforts for many years since they are very effective inhibitors and were often beneficial in improving the compatibility of the inhibitors with the HCl formulations. While oxygen based acid corrosion inhibitors are also in commercial use, they are usually formulated in conjunction with quats.
As environmental regulations become more stringent, some compounds are being banned or are listed for substitution. In the United States and Canada, producers and service companies alike are developing product standards to improve their portfolios in an effort to proactively address environmental concerns and to be responsible corporate citizens. Our efforts were focused on developing oxygen-based inhibitors that met or exceeded the current regulations and requirements established by various governments, producers and service companies. The target was to formulate an inhibitor that contained only environmentally acceptable components, and specifically excluding propargyl alcohol, pyridine and quinoline quats, US EPA Priority Pollutants, nonylphenol ethoxylates (NPE), BTEX, methanol, ethylene glycol and ethylene glycol monobutyl ether (EGMBE). Developing an all oxygen-based inhibitor proved to be quite challenging.
Sour Service Assessment for Aging Assets and Pipelines
Authors: Marsh Zeinab , Marsh Jonathan 
Published: May 2012

Abstract
One of the most problematic issues facing aging assets and pipelines in the offshore UK oil and gas industry is exposure to increasing levels of H2S. Increasing levels of H2S can occur due to a number of factors. H2S can be generated within pipelines or topsides facilities due to poor microbial control, leading to SRB activity. This can affect the facilities and pipelines themselves, and anything downstream. H2S can also be generated by field souring, where SRB contamination of the reservoir has occurred due to poor microbial control of injection water. Finally, assets that have produced sweet gas over the majority of their lives may become gas deficient, requiring gas import for start up, gas lift and fuel gas purposes. Even though these assets have been exporting sweet gas, the only gas that may be available for import may be sour. In all of these cases, the existing infrastructure may have been constructed for sweet or slightly sour service, and may now face exposure to sour environments beyond the original design criteria, or beyond the materials limits defined by ISO 15156. In such circumstances, or where a new operator is taking over operatorship of older assets, a sour service assessment of the facilities and pipelines is strongly recommended. This publication describes the sour service assessment process. It also describes the justification criteria for continued operation where materials are found to be non compliant, and the remedial actions required where a suitable justification cannot be put in place. It will also discuss the generic findings from assessments performed on a number of assets and pipelines in the UK sector, and examine in detail the assessments performed for the TAQA Bratani assets and pipelines.
Trichophagia and Trichobezoar: Case Report
Authors: Tiago Santos , Nuno Madeira , João Alcafache , Carla Vicente , Gonçalo Molinar , Joana Noronha 
Published: May 2012

Objective:Trichobezoar consists of a compact mass of hair occupying the gastric cavity to a various extent. When the trichobezoar extends past the duodenum it is better referred to as Rapunzel Syndrome. Although trichobezoars are well described in terms of surgical diagnostic and procedure, there are only but very scarce reports on psychiatric literature, usually associated with trichotillomania. The authors present a clinical case of trichobezoar and discuss the most relevant aspects concerning this entity.Methods:Presentation of psychiatric and surgical data concerning the case report. Previously reported cases are also mentioned.Results:Report of a 27-year-old female patient with a trichobezoar submitted to surgical removal, with a prior intervention 4 years before also due to trichobezoar, and with unknown psychiatric antecedents or follow-up.Conclusions:A trichobezoar represents a serious surgical condition. It is important to consider such diagnosis in face of suggestive symptoms, even if signs of trichotillomania are not present. The discrepancies between the prevalence of trichotillomania and trichobezoars due to trichophagia may be due to issues related to self-selection of patients and symptom severity. Such issues may also be important in the study of impulsive-compulsive spectrum models and to their relevance to impulse control disorders.
The effect of anatase crystal morphology on the photocatalytic conversion of NO by TiO2-based nanomaterials
Authors: Abreu Marco , Morgado Edisson , Jardim Paula , Marinkovic Bojan 
Published: May 2012

Abstract
Hydrogen titanate nanotubes (H-TTNT) were synthesized by the alkali hydrothermal method followed by proton exchange and then submitted either to thermal treatment or to acid hydrothermal reaction to generate TiO2-anatase nanocrystals of different morphologies. The samples were characterized by XRPD, TGA, sulfur analysis, N2 physisorption, UV-Vis spectroscopy and TEM. Their photocatalytic activities were determined by measuring the NO conversion in inert gas stream passed through the powder catalyst bed under UV radiation. Incomplete transformation into anatase resulted in nanomaterials with low activity due to coexistence with H-TTNT or TiO2-B precursors. Anatase specimens derived from H-TTNT aged in strong sulfuric acid media contained equidimensional nanoparticles, but retention of sulfate negatively affected their photocatalytic activity. Combining milder acidic pH with higher aging temperature, allowed synthesis of a sulfate free anatase with the same optical properties and specific surface area as the counterpart produced by calcination of H-TTNT at 550°C; however, the former exhibited truncated bi-pyramid nanocrystals and the other adopted the form of nanorods. This latter showed the highest photocatalytic activity for NO abatement, outperforming the benchmark photocatatyst TiO2-P25; this improved activity was tentatively ascribed to the maximization of high energy {001} facets in anatase nanorods formed during calcination of H-TTNT.
Trans influence of triphenylphosphines and pseudohalogens on Ni-S bonds: Synthesis, spectral and single crystal X-ray structural studies on NiS2PN and NiS2PC chromophores
Authors: Ramalingam Kuppukkannu , Thiruneelakandan Raghavan , Bocelli Gabriele , Righi Lara 
Published: May 2012

Abstract
Trans influence of triphenylphosphines and pseudohalogens on Ni-S bonds of NiS2PN and NiS2PC chromophores has been investigated by synthesizing and characterizing them. The complexes show the characteristic thioureide IR band at ∼ 1530 cm−1. Electronic spectrum of the cyanide analogue shows a strong blue shift relative to others. X-ray structures of [Ni(pipdtc)(4-MP)(NCS)] (1), [Ni(pipdtc)(PPh3)(NCS)] (2) and [Ni(pipdtc)(PPh3)(CN)] (3) (pipdtc = piperidinecarbodithioate anion, 4-MP = tri(4-methylphenyl)phopshine) are reported. Ni-S bond distance trans to 4-MP(1) is longer than the distances in (2) and (3) and Ni-S bond distances trans to Ni-NCS/CN decrease as follows: (3) &gt; (2) &gt; (1). Particularly, 4-MP shows a highly significant trans influence than triphenylphosphine on Ni-S bond. Similarly, CN− exerts a marginally significant trans influence compared to NCS-. Thioureide C-N distances are relatively very short due to the drift of electron density towards the metal. The Ni-N-C angle (163.5(2)°) observed in (2) indicates deviation from linearity to a larger extent compared to that in (1) (176.3(3)°) due to the steric effect of the 4-methyl group. The reduction potentials (CV) for the mixed ligand complexes are much less compared to that of the parent NiS4 chromophore due to the π-acidic phosphines.
Electrode mechanism and voltammetric determination of selected guanidino compounds
Authors: Skrzypek Sławomira 
Published: May 2012

Abstract
The present review describes the recent results on the electrochemical activity of bio-guanidino compounds, such as famotidine, metformin, acyclovir, ganciclovir, zanamivir, moroxydine as well as guanidino compounds, such as S-[(2-guanidino-thiazol-4-yl)methyl]isothiourea hydrochloride, 2-guanidino-1,3-thiazole, 2-guanidinobenzimidazole. The focus is on analyzing the electrode mechanism of the guanidino compounds at the hanging mercury drop electrode and at the silver amalgam film electrode, as well as on the character of the square wave (SW) voltammetric signals. It has been stated, that the compounds can act as electrocatalysts — they are protonated and adsorbed at the surface of the electrode, after which the protonated forms of the compounds are irreversibly reduced, yielding their initial form and hydrogen. The experimental adsorption data obtained by measuring the differential capacity of the double layer, the zero charge potential, and the surface tension at the zero charge potential have established the adsorption processes underlying their electrochemical activity. The analytical application of the obtained voltammetric signals in the determination of these compounds in biological samples is also presented. This review concentrates on our own results in the context of general developments in the field.
Temperature effects on the adsorption of polyvinyl alcohol on silica
Authors: Wiśniewska Małgorzata 
Published: May 2012

Abstract
The influence of temperature on the adsorption of polyvinyl alcohol (PVA) on a silica surface was studied from 15–35°C. The structure of the polymer adsorption layer was determined from spectrophotometric, viscosity and thermogravimetric measurements. The amount of PVA adsorbed, macromolecules’ conformation in solution, thickness of the polymer adsorption layer, and changes in the heating curve of SiO2 with adsorbed polymer were determined. Temperature influences the PVA chain conformation in solution and the structure of the polymer adsorption layer. A temperature rise causes relaxation of polymer coils which results in an increase in the linear dimensions of PVA chains in the solution, the creation of a thicker adsorption layer, and an increase in polymer adsorbed. Polymer adsorption on the silica surface also causes changes in the heating curve of these systems. The mass losses due to heating are smallest for the systems obtained at 15°C because the least polymer is adsorbed at this temperature.
Extraction-spectrophotometric investigations on two ternary ion-association complexes of gallium(III)
Authors: Stojnova Kirila , Gavazov Kiril , Toncheva Galya , Lekova Vanya , Dimitrov Atanas 
Published: May 2012

Abstract
Complex formation and liquid-liquid extraction were studied in systems containing Ga(III), azoderivative of resorcinol {4-(2-pyridylazo)resorcinol (PAR) or 4-(2-thiazolylazo)resorcinol (TAR)}, 2,3,5-triphenyltetrazolium chloride (TTC), water and chloroform. The optimum conditions w.r.t. pH, extraction time, concentration of ADR and concentration of TTC for the extraction of Ga(III) as an ion-associate complex were found.. The composition of the extracted complexes, (TT+)[Ga(PAR)2] (I), (TT+)[Ga(TAR)2] (II) or (TT+)2[Ga(OH)(TAR)2] (III), and the constants of association (β) between 2,3,5-triphenyltetrazolium cation (TT+) with corresponding anionic chelates were established by several methods. The constants of distribution (KD) and extraction (Kex) of the principal species I and III were determined as well. The apparent molar absorptivities of the chloroform extract at the optimum extraction-spectrophotometric conditions were ɛ′510=9.5×104 L mol−1 cm−1 (I) and ɛ′530=4.6×104 L mol−1 cm−1 (III). The validity of Beer’s law was checked and analytical characteristics that were calculated are reported herein.