bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Humidity, Moisture and Temperature on the Electric Properties of Self-Sensing Cement Pastes for Post-Abandonment Well Monitoring
Authors: Carísio Pedro de Almeida , Carvalho Carlos Pessanha Costa , Cocchiarale Marcela de Oliveira , Ferreira Lincoln Homero Thome , Mendoza Reales Oscar Aurelio , Fairbairn Eduardo de Moraes Rego , Toledo Filho Romildo Dias 
Published: October 2019

Abstract
The self-sensing capability is a well-studied property of carbon nanotubes blended cement pastes intended for civil construction applications. Nevertheless, most of the studies that can be found in the literature were performed at room temperature, natural humidity and atmospheric pressure. It is necessary to understand how down-hole conditions affect the electrical response of this intelligent material to identify its potential application in the oil industry. This paper presents a study on the effect of relative humidity, internal moisture and temperature on the electric properties of self-sensing cement pastes. These pastes were manufactured with class G cement blended with carbon nanotubes and are intended to be used as an intelligent material capable of auto monitoring its internal stresses and deformations during the post-abandonment phase of a well. Carbon nanotubes blended cement pastes were molded in 2.5 × 2.5 × 11.5 cm3 prisms embedded with copper electrodes. The produced samples were exposed to different relative humidity, internal moisture and temperature conditions and their electrical resistivity was measured at each condition by connecting a DC power supply and a multimeter to the embedded electrodes. Relative humidity and temperature was varied in a climate chamber, already internal moisture was varied by saturating and partially drying the material. It was found that the electrical resistivity of the studied pastes is more highly sensible to internal moisture and temperature, while relative humidity had a lower effect under the studied conditions. These results lead to the conclusions that the electrical response of carbon nanotubes blended pastes is highly affected by environmental conditions, and that for oil-well applications it is necessary to develop correction models that allow an accurate measurement of the internal stresses and deformations of the material.
Virtual Reality for Visualization of Enhanced Oil Recovery Processes at Nanoscale
Authors: de Almeida James Moraes , Miranda Caetano Rodrigues 
Published: October 2019

AbstractThis work provides an immersive visualization of oil & gas relevant systems and enhanced oil recovery (EOR) processes at the nanoscale by coupling molecular dynamics (MD) simulations with gamming virtual reality (VR) technologies. The main objective is to understand oil/brine/rock interfaces at molecular level and identify the underlying EOR mechanisms at the atomic scale. Within this immersive experience, the user can directly interact and enhance its perception of atomic environment for EOR applications. The experiences cover nano-EOR, nano-IOR and low-salt processes at nanoscale based on MD calculations of nanoparticles at oil-brine interfaces, oil-brine at silica nanopores and calcite-brine-oil interfaces, respectively. The MD simulations are performed with the Lammps package. The visualizations were done with an HTC Vive and Oculus Rift virtual reality headsets with the Nomad VR and Unitymol software. For the Nomad VR, the trajectories are previously saved from a Lammps molecular dynamics simulation, whereas, for the Unitymol, the simulation with Lammps is performed on-the-fly through the iMD (interactive MD) plugin. The user can visualize and navigate through the trajectories using the Nomad VR. Furthermore, the Unitymol also allows the user apply forces on selected molecules on real time during the VR experience. As means of comparison, the visualization was also performed with cell-phone based VR headsets with the Nomad VR application. Our demonstrations show that VR combined with molecular simulations can be an interesting and attractive way to improve the perception of the nanoscale for the general public. Additionally, it is an emergent tool to characterize, improve the understanding and provide molecular insights about nanosystems and the EOR methods, and also to be integrated with on-going digitalization processes within the oil & gas industry.
Multiscale Coupling between Molecular Simulations and Reservoir Simulator: Geochemical Reactions for Low Salinity Water Injection in Carbonates
Authors: Baptista Alvaro David Torrez , Salvador Michele Aparecida , Silva Gabriela Dias da , Martins Ernane de Freitas , Almeida James Moraes de , Miranda Caetano Rodrigues 
Published: October 2019

Abstract
This work, is based on the multiscale coupling between molecular simulations and reservoir simulators, to explore the brine composition for enhanced oil recovery via the low salinity water injection (LSWI) processes. To achieve this goal, molecular simulations were performed, providing physical-chemistry parameters to reservoir simulators and validate the proposed brine compositional model. The key data required within reservoir simulators are related to the chemical reactions, which are occurring due to the LSWI process, such as their free energies, kinetic constants, ionic strengths, chemical activities, and activation energies. To improve the accuracy of this input dataset, the main aqueous phase geochemical reactions were mapped, adsorption energies of hydrocarbons and brine ions on calcite surface were determined and ions-bearing calcium carbonate were evaluated. The calculations were based on the density functional theory (DFT) and classical molecular dynamics (MD) using Quantum-ESPRESSO and LAMMPS codes, respectively. The geochemical reactions that take place at mineral dissolution and ionic release, related to the LWSI process (MgSO4, CaSO4, BaSO4, Na2CO3, and CaCO3), were also determined. The obtained chemical equilibrium showed that the MgSO4 dissolution reaction was favored, while other minerals did not show a similar trend. Adsorption studies of organic the molecules naphthalene and anthracene over different surface sites were performed. The adsorption energies were similar for both molecules, where the most favorable configuration has the rings oriented parallel to the mineral surface. The potential of mean force obtained for brine ion adsorption suggested that there were no barriers for adsorbing Ca2+ and CO32- brine ions on calcite surface. In contrast, the other ions adsorption (Na+ and Cl-) have presented higher estimated activation energies. The energetic difference showed that the SO42- incorporation in calcite is more favorable than Mg2+. The Ba2+ showed unfavorable incorporation energy. The thermodynamic properties (free energies, entropies, and heat capacities) were calculated from the vibrational properties. Obtaining such input data by molecular simulations can significantly reduce uncertainties, by increasing the reservoir simulators predictive power, facilitating the optimization and understanding of the processes involved in the injection of low salinity fluids. From these results, the obtained equilibrium constants, free energies and adsorption energies can be used as input data in further reservoir simulators. In addition, it would allow the validation of the proposed model from the understanding of the physical processes underlying LSWI.
Decreasing Well Construction Costs for Mature Fields in the Recôncavo Basin
Authors: Loza Prado Jaime Andres , Rosales Juan , Finney Troy , Venuto Marcos , Hupp Anderson , Camara Francisco 
Published: October 2019

Abstract
The Recôncavo basin is located in northeast Brazil and has several mature fields that have been producing for more than 40 years. After more than three years without drilling activity, an integrated services model was implemented as a different working methodology for optimizing well construction. This work describes in detail the applied methodology and illustrates how it has positively impacted well construction times and thus costs.
An integrated services model approach was applied. Instead of many technical representatives for each specialty, as performed in previous projects in the area, an integrated services coordinator was assigned as a single contact point for the operator to improve communication, document lessons learned, support logistics, follow up with project KPI, daily reporting, operational meetings, and field support on critical operations. Furthermore, technologies that had never been used in the area were applied, such as oil based mud (OBM), electromagnetic measurement while drilling (MWD), rigless cement evaluation, PDC bits and cased hole evaluation. These logging systems were chosen because of the high risk of losing openhole wireline tools as a result of fluid-loss issues in the production hole section, and it worked very well as an innovative option in which a synthetic profile was obtained from the cased hole wireline logging data. This profile was obtained and adjusted based on information from neighboring wells in the same field.
Wells of the previous drilling campaign involved the use of traditional tools and relatively low nonproductive times, but at inefficient well construction rates. Because of the integration acquired using the integrated services approach, a more collaborative environment was created and project stakeholders collaborated to achieve project success and solve specific issues. As a result of the integrated service approach, and the application of new technologies in the area, instant improvement was observed compared to previous drilling campaigns. During project execution, drilling times were positively impacted and risk mitigated, reflecting a continuous improvement tendency and consistent learning curve.
This paper illustrates how an integrated services approach and the introduction of proven technologies were successfully applied in the Recôncavo basin, which can be used by engineers as reference to help achieve similar or better results. It also demonstrates that, even in mature fields or in very well-known areas, there is room for improvement.
Seal Qualification and Single-Trip Lockdown Sleeve Reduces Risk Through Innovative and Advanced Technology
Authors: Ellisor Scott Patrick , Queiroz Rodrigo Albani , Gaban Carlos Eduardo Martins , Eppinghaus Guilherme Pedro , Lucci Bruno Naressi 
Published: October 2019

Abstract
The oil and gas industry continues to face the need to reduce risk and the overall cost of operations as a means to compensate for lower oil prices. Conventional designs and methods are economically infeasible when drilling offshore in the current economic environment pushing the manufacturer to re-evaluate how to reduce risk and drive down costs. This paper describes a new and advanced way to drive down cost and reduce risk while drilling by reducing the number of trips into the well, adding significant value to the end user.
The subsea wellhead system functions in a dynamic, complex environment; however, the qualification process of this system commonly employs relatively static test fixtures. These critical seal/casing hanger barriers within this wellhead system are presented, discussed and shown with exhaustive validation efforts necessary to evaluate relevant failure modes. Within the wellhead system, loads are typically resultant of a combined state including pressure and temperature. The validation of these components is aimed at defining the performance of the system in these states while detailing the limitations that one performance aspect may have on another. (Brown, 2017)
This wellhead system offers reduced cost, simplified installation procedures and lower operational risk. Traditionally, a wellhead system would require a drilling lockdown sleeve during the drilling operations; however, prior to running the lockdown sleeve, many additional trips are made into the well to verify the position of the hanger in the wellhead. By eliminating the lockdown sleeve, the operator will save multiple trips into the well, therefore, reducing NPT and cost of operations. This is proven by performing well-defined subsea seal/casing hanger testing validation to accurately simulate the installed configuration.
Because of this innovative seal assembly design, development of a single trip lock down sleeve was designed for wellhead systems requiring extremely high lock down requirements. The lock down sleeve does not require a trip with a Lead Impression Tool to clean the wellhead and measure the position of pre-installed equipment. This allows the user to save trips previously required by legacy designs, reducing time spent down hole and reducing overall cost.
The antiquated claims of not being able to provide metal-to-metal sealing in dynamic applications are dispelled based on performed validation testing of a metal-to-metal seal (with no elastomeric/thermoplastic elements) which accurately represents field scenarios, in which combined pressure/temperature, load and hanger movement are applied. Therefore, the need for costly trips into the well is shown to be unnecessary with the installation of the single trip lockdown sleeve and/or high capacity casing hanger/seal assembly.
Libra Digital: An Integrated View
Authors: Silva Flavia Pacheco , Anjos Sylvia Couto , Ferreira Ana Cristina Florentino , Wambersie Olivier Edward , Moura Daniela Gonçalves , Pinheiro Luciana Frechette , Santos Bruno Evione , Oliveira Thais Eleuterio R. 
Published: October 2019

Abstract
Digital transformation has revolutionized the way companies operate in the market, changing their work processes with the inclusion of new technologies and thus influencing their culture. In the oil and gas industry, this phenomenon is more recent and is increasingly accentuating. Its importance is such that companies are adjusting their structure to accelerate the implementation of this new culture.
At Petrobras this movement was no different, the corporate area responsible for the digital transformation in the company orchestrates this movement, identifying new opportunities, coordinating corporate initiatives and following the fronts already being implemented in other areas, ensuring alignment with institutional guidelines.
Libr@Digital program aligned with Petrobras’ Digital Transformation corporate initiative and it has been working as a testing environment to validate the solutions before scaling them up to Petrobras operations. This is so, because Libra in its structe congragates all disciplines that integrate the E&P activities, from exploration to oil offloading.
Improved Reamer Cutter Blocks Optimizes the Brazilian's Pre Salt Well Construction
Authors: Silva Leonardo Pacheco da , da Mata Pedro Oliveira , Oliveira Raphael Cristiano , Almeida Junior Carlos Alberto , Benitez Matamoros Alina Meylin , Florido Jorge de Carvalho Lopes 
Published: October 2019

Abstract
This paper will describe the improvement made to the reamer cutter blocks to enhance its durability and optimize the Pre-salt Well Construction
Currently, most of the Brazilian's Pre-Salt wells have the last phase built-in 12.25in. In some situations, it is necessary to drill oil wells in a giant offshore field wells with five phases, enlarging the third phase from 18.125in to 22in. The high abrasiveness encountered at this phase increased the number of runs needed to drill it and, consequently, time and costs that encouraged the development of solutions.
This work relates what has been observed during the last years about reaming difficulties, specifically, in the enlargement from 18.125in to 22in when facing abrasive formations. Petrobras specialists analyzed these events and concluded the matrix of the reamer's cutter blocks was wearing faster and losing the capacity to hold the PDC cutters. The hole enlargement company, that Petrobras works for nowadays, developed a process that increased the resistance of the cutter blocks by increasing the hardness of the surface material prior to the brazing of the cutters. Then, Petrobras has had the opportunity to use both modified and common cutter blocks in a challenging operation to compare their durability and the results were completely satisfactory. The modified cutter blocks had much less wearing on the same formations. Based on this operation, we can conclude this process is validated since improved the reamer cutter blocks quality and its lifetime.
This paper can serve as a guide to reduce operations costs and to optimize well construction when there are concrete possibilities to enlarge abrasive formations.
Role of neuroimaging and electroencephalogram in first unprovoked seizures in children from Cairo
Authors: Elfeshawy Mohamed S , Afia Ali A , Alsawah Ahmed Y , Mohammed Mahmoud I , Abdelkader Ann A 
Published: October 2019

Background
First unprovoked seizure (FUS) and complex febrile seizure (CFS) are common pediatric issues of great debate with respect to the role of electroencephalogram (EEG) and neuroimaging in their diagnosis.

Aim
To determine the frequency of abnormal EEG and neuroimaging results in children with FUS and CFS and to detect the correlation between EEG and neuroimaging results.

Patients and methods
A total of 100 children (6 months to 12 years of age), who presented with first afebrile or CFS underwent EEG and neuroimaging (computed tomography and/or MRI). This was a prospective randomized controlled trial.

Results
A total of 100 cases within the age group 6 months to 12 years were recruited. FUS was seen in 63 cases and CFS in 37 cases. Overall, 69.8% cases of FUS were generalized and 30.2% were focal. The prevalence of EEG abnormality was found in 33% of the whole studied population: 44.4% in patients with FUS and 13.5% in patients with CFS. The prevalence of neuroimaging abnormality was found in 15% of the whole studied population: 20.6% in patients with FUS and 5.4% in patients with CFS. Neuroimaging abnormality was seen more commonly in those patients who had an abnormal EEG, with a statistically significant increase in cases with FUS.

Conclusion
EEG and neuroimaging abnormalities were more prevalent in children with FUSs than those with CFSs. Abnormal EEG and neuroimaging were more common in children with partial seizures than those with generalized seizures. Neuroimaging was abnormal in a significant number of children having abnormal EEG, so neurologically free patients having normal EEG can be safely discharged without neuroimaging, if follow-up is assured. When EEG is abnormal in FUS, the probability of having abnormal neuroimaging increases as compared with those cases where EEG is normal. In case of generalized seizures, patients with abnormal EEG may have abnormal computed tomography/MRI scans, but there are fewer possibilities of a patient with abnormal EEG to have a normal neuroimaging. In partial seizures, abnormal EEG increases the risk of having abnormal neuroimaging than in generalized seizures, and normal EEG in partial seizures markedly decreases the risk of having an abnormal neuroimaging generalized seizures. CFSs in otherwise neurologically free children rarely indicate the presence of lesion on neuroimaging even if associated with EEG abnormalities. Neuroimaging abnormalities in neurologically free children with FUS and CFSs do not require urgent intervention.
The role of dexmedetomidine infusion on intraoperative desflurane and fentanyl requirement in spine surgery
Authors: Elsayed Ruqaya M , Shabaan Amira A 
Published: October 2019

Introduction
Dexmedetomidine is a potent selective agonist of α2 adrenoceptor having sedative, amnestic, sympatholytic, and pain-relieving properties without producing significant respiratory depression and promotes hemodynamic stability when used as an adjuvant during general anesthesia.

Aim
The objective of this study was to evaluate the effect of dexmedetomidine infusion on desflurane consumption, intraoperative fentanyl requirement, and hemodynamic changes.

Patients and methods
Sixty patients of American Society of Anesthesiologists I and II enlisted for elective spine surgery were randomly classified into two groups: group D dexmedetomidine group received preoperative intravenous dexmedetomidine 0.5 μg/kg over 10 min followed by 0.25 μg/kg/h (1 ml, 100 μg diluted with normal saline in 20 ml syringe) intraoperative infusion till the end of surgery and group P, the placebo group received a similar volume of normal saline. Desflurane consumption and intraoperative fentanyl requirement were recorded as well as intraoperative hemodynamic changes.

Results
Desflurane consumption and intraoperative fentanyl requirement were significantly lower in group D (P<0.001) as well as there was a significant decrease in heart rate and mean arterial blood pressure (P<0.05) in D group

Conclusion
Dexmedetomidine infusion resulted in significant reduction of desflurane consumption and intraoperative fentanyl requirement with significant decrease in heart rate and mean arterial blood pressure.
Open mesh versus laparoscopic mesh repair of inguinal hernia
Authors: Abd El-Ghaffar Ahmed Abd E , Elshafey Mohammed H , Abd El-Moneam Ghonaim Amer Y 
Published: October 2019

Introduction
Inguinal hernia repair is the most frequently performed operation in general surgery. The standard method for inguinal hernia repair had changed little over a hundred years until the introduction of synthetic mesh which can be placed by either using an open or a laparoscopic approach. The cause of groin hernia is probably multifactorial, with one or more factors applying in any particular case. Among the factors predisposing to groin hernia are persistence of the processus vaginalis, weakness of the shutter mechanism of the inguinal canal, raised intraabdominal pressure, heavy physical exertion, loss of integrity of the fascia transversalis, metabolic factors leading to the production of abnormal collagen fibers, cigarette smoking, genetic influences, spontaneous or iatrogenic abdominal wall trauma, aging, and general factors causing weakness of the abdominal wall muscles and fascia.

Aim
To compare the merits and potential risks between cases subjected to open mesh repair versus cases subjected to laparoscopic mesh repair of inguinal hernia.

Patients and methods
The patients were selected from those attending the surgical outpatient clinics of Al-Azhar University Hospitals (El-Hussein and El Sayed Galal), during the period from January 2017 till January 2019.

Results
This study includes 100 patients with inguinal hernias, where 50 of them were repaired laparoscopically by the transabdominal preperitoneal technique whereas the other 50 were repaired through the Lichtenstein tension-free repair. Patients were followed up by routine clinical examination for 6–18 months (with mean 12 months of follow-up) to calculate the incidence of postoperative complications and recurrence rate during the relatively short period of follow-up.

Conclusion
The Lichtenstein tension-free hernioplasty is the gold standard of groin hernia repair owing to the simplicity of the technique, the short learning curve, the low incidence of recurrence, and the low incidence of easily controllable postoperative complications as well as the relative low price and less expensive instruments required. However, transabdominal preperitoneal repair should be reserved for bilateral and recurrent inguinal hernias as long as the case is fit for general anesthesia or it is best suited to the younger patients in good general health who cannot afford an extended time away from work or who are suspected for a contralateral inguinal defect, and that it should be performed by an experienced surgeon to decrease the risk of complications and the operative time as well as the recurrence rates.