bluuebunny/crossref_metadata_2025 huggingface dataset:
Cornea Regeneration as an Alternative to Human Donor Transplantation
Authors: Brunette Isabelle ,   Professor and Senior Consultant, Department of Ophthalmology, University of Montreal, Canada,   Assistant Professor, University of Ottawa Heart Institute, Canada,   Professor in Regenerative Medicine, Department of Clinical and Experimental Medicine, Linköping University, Sweden, Alarcon Emilio I , Griffith May
Published: January 2016

There is a need for an alternative to human donor corneas as the availability of good-quality tissues remains limited, with this situation potentially worsening as the population in many countries is progressively ageing. There have been numerous attempts to develop corneal equivalent as alternatives to donated human corneas as well as prostheses. In this short review, we focus on the efforts in bioengineering implants that promote regeneration by Canadian researchers, including our current team of authors. The examples of technologies developed that we describe include biomaterials that allow for partial regeneration of corneal tissue, self-assembled cornea constructs and cell-free corneal implants that promoted regeneration when evaluated in clinical trials in Europe.
Changing Paradigms of Treating Severe Keratitis in Dry Eye Disease
Authors: Baudouin Christophe ,   Quinze-Vingts National Ophthalmology Hospital, Paris, France,   Santen SAS, Evry, France,   Department of Neuroscience, Ophthalmology, University of Padua, Italy,   St Eriks Eye Hospital, Stockholm, Sweden, Amrane Mourad , Leonardi Andrea , van Setten Gysbert
Published: January 2016

These proceedings are based on a symposium, presented at the European Society of Ophthalmology 2015 Congress in Vienna, Austria on 8 June 2015. The symposium was arranged by Santen to bring together leaders in ophthalmology with the objective of exploring advances in the treatment of severe keratitis in dry eye disease (DED). DED is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance and tear instability with potential damage to the ocular surface. Abnormalities at the ocular surface can affect all tear dynamic components, resulting in a vicious cycle that reinforces/sustains DED. Ciclosporin (CsA) is thought to exert an anti-inflammatory effect on ocular surface cells. This compound should be in the near future one of the principal advances in the treatment of DED for blocking the vicious cycle of the disease. Extensive formulation development work has led to the availability of a well-tolerated, stable cationic nanoemulsion, designated as Novasorb® technology. This technology has been used in the first European approved CsA 1 mg/mL eye drops emulsion (Ikervis®) for the treatment of severe keratitis in adult patients with DED, which has not improved despite treatment with tear substitutes. Clinical trials involving over 900 patients have demonstrated a good safety and tolerability profile and significant clinical efficacy of this formulation with a once-daily dosing regimen. CsA 1 mg/mL eye drops were evaluated in the pivotal phase III SANSIKA study, which confirmed the positive benefit–risk profile of CsA 1 mg/mL eye drops for the treatment of severe keratitis in DED. An assessment of ocular surface health requires: listening to the patient, the use of simple diagnostic tools, an expertise in examination, including use of microscopy, and an up-to-date knowledge of current models of DED.
The Challenge of Glaucoma Surgery in the Cataract Patient – Where Are We Now?
Authors: Olivier Mildred MG ,   Professor, Department of Surgery, Division of Ophthalmology, Chicago Medical School, Chicago, US
Published: January 2016

Choosing the best approach for cataract removal in glaucoma patients depends on the extent of glaucoma-related damage and the medications in use to control IOP. Micro-invasive glaucoma surgery offers additional options for patients needing combination surgery without altering the conjunctiva.
Back to the Future – Has Medical Treatment of Glaucoma Improved?
Authors: Pfeiffer Norbert ,   Department of Ophthalmology, Mainz University, Germany,   Glaucoma Service and Perimetry Unit, Department of Ophthalmology, Semmelweis University, Budapest, Hungary,   University – Eye Hospital Dresden, Germany, Holló Gábor , Pillunat Lutz E
Published: January 2016

These proceedings are based on a symposium that were presented at the European Society of Ophthalmology 2015 Congress in Vienna, Austria on 8 June 2015. The symposium was arranged to bring together leaders in ophthalmology to explore advances in the medical treatment of glaucoma. Many patients with glaucoma require combination therapy. Fixed-dose combinations represent a significant improvement in the medical treatment of glaucoma, being advantageous in terms of their association with good compliance and elimination of the wash-out effect. While preservatives are a historic necessity, their use is associated with increased ocular surface disease and higher indirect cost. The novel preservative-free tafluprost/timolol fixed-dose combination provides mean diurnal intraocular pressure (IOP) lowering of up to 40 % from baseline and demonstrates similar efficacy with other prostaglandin/timolol fixed-dose combinations, is superior to its individual components and non-inferior to its individual components given concomitantly. The tafluprost/timolol fixed-dose combination is well-tolerated with low prevalence of hyperaemia. It is generally accepted that function loss follows structural damage and that normal-pressure glaucoma (NPG) and high-pressure glaucoma (HPG) represent that same disease, separated by an arbitrary pressure level. However, functional damage (pattern electroretinogram) is detectable prior to structural damage and NPG patients show less retinal nerve fibre layer and visual field loss compared with the same optic nerve head morphology HPG patients. NPG patients seem to lose connective tissue first whereas, in HPG, patients seem to lose retinal nerve fibres first. Thus, whether NPG and HPG are the same disease is an open question.
The Vitreoretinal Interface in Retinal Vein Occlusions – A Clue for Surgery?
Authors: Brunner Simon ,   Ophthalmologist, Department of Ophthalmology, The Rudolph Foundation Hospital, Vienna, Austria
Published: January 2016

Retinal vein occlusions are still one of the leading retinal vasculopathies with a strong impact on the quality of life. Despite the success in symptomatic treatment with anti-vascular endothelial growth factor (VEGF) medication, no real causal therapy has been developed so far. As most of the pathogenetic changes have been observed in the vitreoretinal interface, actual therapeutic strategies are being focused on this area. Modern surgical techniques may help to release vitreovascular traction, stop cytokine activation and improve retinal oxygenation.
Ocriplasmin Efficacy – An Analysis of Real-World Results From 2013 to 2015
Authors: Kuppermann Baruch D ,   Professor of Ophthalmology and Biomedical Engineering; Chief, Retina Service; Vice Chair, Academic Affairs,   Ophthalmology School of Medicine, Gavin Herbert Eye Institute, University of California, Irvine, California, US
Published: January 2016

As the eye ages, physiological events predispose it to posterior vitreous detachment. This normal ageing process can be complicated by persistent vitreomacular adhesion, which may develop into vitreomacular traction (VMT) accompanied by visual symptoms if forces are great enough to cause macular anatomical changes. Ocriplasmin represents a pharmacological treatment option for VMT resolution. The results of studies and cases reporting ocriplasmin treatment subsequent to US Food and Drug Administration (FDA) approval are presented. Analysis of 26 studies showed that 23 (88 %) reported VMT resolution efficacy results above 40 %, well higher than the 26.5 % efficacy reported in the two pivotal clinical trials. Subsequent analysis revealed patient baseline characteristics predicted to have higher VMT resolution. These clinical trial results were confirmed in 14 post-approval studies with subgroup analysis, consistently showing that patients with specific criteria had higher resolution than their non-criteria-matching counterparts. Visual acuity (VA) group averages were reported by 13 of 18 studies, with 12 (92 %) reporting VA improvement. Case reports of patients receiving ocriplasmin showed 10 of 15 (67 %) with VA improvement; the five cases reporting visual decline reported relatively short follow-up periods. A full understanding of ocriplasmin efficacy in clinical settings will help further identify ideal candidates for ocriplasmin treatment.
Optical Coherence Tomography Angiography of the Retinal Microvasculature using the Zeiss AngioPlex
Authors: Staurenghi Giovanni ,   Department of Biomedical and Clinical Science ‘Luigi Sacco’, Sacco Hospital, University of Milan, Milan, Italy,   Department of Ophthalmology, University of Coimbra, and Association for Innovation and Biomedical Research on Light and Image (AIBILI), Coimbra, Portugal,   University Hospital Pellegrin, Bordeaux, France, Vaz Jose Cunha , Korobelnik Jean-Francois
Published: January 2016

AngioPlex™ optical coherence tomography (OCT) is a new approach to diagnostic imaging in retinal disease. This technology uses amplitude and phase aspects of the OCT signal and novel algorithms to enable highly detailed visualisation of the retinal microvasculature. This system detects capillary flow rather than the presence of an injected dye. Unlike fluorescein angiography (FA), AngioPlex OCT imaging can discriminate capillaries at the superficial and deep retina and can also generate a colour map of the retinal vessels providing unparalleled views of diseased capillaries and net structures. Retinal and choroidal pathologies that are amenable to AngioPlex OCT examination include diabetic retinopathy (DR), vein occlusions, age-related macular degeneration and pathological myopia. In addition, AngioPlex OCT can be used to explore the vasculature of the optic nerve. These applications have considerable potential for improved retinal and choroidal disease diagnosis, but further experience and debate are needed to fully interpret the images. AngioPlex OCT is rapid, non-invasive and improves the patient experience and has been granted US Food and Drug Administration (FDA) 510(k) clearance for clinical use. The convenience and the range of retinal disease applications may encourage widespread adoption of the technology. AngioPlex OCT may therefore become a standard initial examination step for patients with retinal disease prior to and during treatment and may also indicate where further investigations including FA or indocyanine green are necessary.
Intraocular Telescopic Implants for Age-related Macular Degeneration Eyes
Authors: Lipshitz Isaac ,   Director, Lipshitz Vision Center, Herzlia, Israel
Published: January 2016

The vast majority of age-related macular degeneration (AMD) eyes (all dry type –90 % and some of the wet type) do not have any medical treatment that can improve their vision. The only help that they can get are optical solutions and the most adequate are intraocular implanted telescopes. Among the various implanted telescopes that are available (which are reviewed here) the mirror telescope is the newest, smallest, easiest to implant and is the only one that can be used for phakic as well as pseudophakic eyes.
How to Choose the Best Cross-linking Procedure in 2016
Authors: Hafezi Nikki ,   ELZA Institute, Dietikon/Zurich, Switzerland,   ELZA Institute, Dietikon/Zurich, Switzerland, Hafezi Farhad ,   University of Geneva, Switzerland,   University of Southern California, Los Angeles, US
Published: January 2016

Ever since cross-linking (CXL) technology was introduced into clinical ophthalmology in 1999, the technique has established itself as a standard of care in the treatment of corneal ectasia. The original protocol, referred to as the ‘Dresden protocol’, consisted of 30 minutes of iso-osmolaric riboflavin instillation on a de-epithelialised cornea, followed by irradiation at 365 nm and 3 mW/cm2for 30 minutes. These settings correspond to a fluence of 5.4 J/cm2. A large variety of modifications of this original protocol have emerged in the past years: some of these modifications are backed up by a solid body of research evidence, both clinically and experimentally, whereas other modifications are based on little to no scientific evidence. Navigating through this ‘sea of new protocols’ is becoming increasingly difficult for the treating ophthalmologist. The two most important modifications are transepithelial (epi-on) CXL and accelerated CXL. Most interestingly, they seem to share a final common pathway, which determines efficacy: oxygen dependency.
Auditoria nas parcerias público-privadas: o caso do Tribunal de Contas de Portugal
Authors: Sarmento Joaquim Miranda
Published: January 2016

Este artigo analisa a experiência de auditoria pública nas parcerias público-privadas em Portugal. Ao longo de mais de 10 anos de auditoria, o Tribunal de Contas de Portugal tem feito sérias reservas quanto à forma de utilização dos dinheiros públicos. Ressaltam-se, sobretudo, duas críticas: por um lado, a gestão pública ineficiente dos contratos, com lacunas, quer na fase de preparação e concurso, quer na fase de monitorização e, por outro lado, o incipiente controle orçamental. Apesar das muitas recomendações que o Tribunal de Contas tem produzido e da implementação, muitas vezes, parcial de algumas dessas recomendações, a experiência portuguesa em matéria de PPP é bastante negativa.

 
O processo de mudança dos mecanismos das compras governamentais no Brasil: vantagens e riscos da contratação integrada
Authors: Nóbrega Marcos
Published: January 2016

Uma das mais importantes inovações legislativas dos últimos anos na área de licitações e contratos foi a criação do Regime Diferenciado de Contratações Públicas (RDC) e, mais especificamente, a possibilidade da utilização de um regime de execução diferenciado chamado contratação integrada (design-build). Embora o assunto tenha sido muito debatido e apesar de haver alguma jurisprudência sobre o tema (sobretudo nas licitações da Infraero), a modelagem da contratação integrada ainda suscita muitas dúvidas, preconceitos e polêmica. Esse texto procura mostrar os aspectos positivos e negativos desse tipo de contrato e demonstrar que ainda é cedo para afirmar se a inovação é positiva ou não; e que tudo dependerá de como os atores manejarão os incentivos envolvidos.
There is No Evidence For or Against the Use of Non-Steroidal Anti-Inflammatory Drugs to Reduce the Clinical Duration of Kennel Cough (Infectious Tracheobronchitis).
Authors: Silpa Marc Andrew Charles
Published: January 2016

Clinical bottom line

There is no evidence on which to  judge the efficacy of non-steroidal anti-inflammatory drugs for the treatment of kennel cough.
COPA DO MUNDO DE FUTEBOL E SUA MATERIALIZAÇÃO NA TELEVISÃO ANALÓGICA
Authors: Ushinohama Tatiana Zuardi , Marques José Carlos
Published: January 2016

O estudo objetiva comparar as transmissões da Copa do Mundo de Futebol no sistema televisivo analógico a fim de averiguar como as modificações no aparato técnico refletiram sobre o discurso. Por meio de uma análise qualitativa das transmissões das finais das Copas de 1970 e 1998, observou-se que o aumento das possibilidades oferecidas em função da evolução técnica transformou o processo de simples fixação do acontecimento em um discurso do meio.
Em defesa do realismo, em defesa do cinema
Authors: Souza Gustavo Ramos de
Published: January 2016

O livro O que é o cinema?, de André Bazin, foi reeditado pela Cosac Naify em 2014, tendo o acréscimo de nove ensaios inéditos que não constavam na primeira edição, publicada pela Brasiliense em 1991, além de um texto de apresentação e um apêndice de Ismail Xavier. Dividido em 36 ensaios, o livro traz teorias sobre montagem, cinema de propaganda, realismo, interações entre cinema e outras artes, erotismo, western etc., tendo sempre como ponto de partida a análise dos filmes.
A REPRESENTAÇÃO IDENTITÁRIA DO ADOLESCENTE EM CONFLITO COM A LEI NA MÍDIA PARANAENSE
Authors: Moresco Marcielly Cristina , Ribeiro Regiane
Published: January 2016

Este artigo apresenta os resultados de uma investigação sobre a representação social e a identidade dos adolescentes em conflito com a lei nos conteúdos da mídia paranaense, especificamente, nos jornais Gazeta do Povo e Folha de Londrina. Pretende-se descrever a representação social desses sujeitos a partir das narrativas dos jornais e compreender como são estabelecidas suas identidades no meio impresso. Os procedimentos metodológicos adotados envolvem a análise de conteúdo (Bardin, 1977; Krippendorf, 1990; Fonseca Júnior, 2012) de 39 textos jornalísticos (notícia, reportagem, artigo/opinião e entrevista) publicados no período de maio de 2013 a novembro de 2014. As conclusões apontam para uma representação social negativa e incriminadora dos adolescentes, indicando uma identidade construída por marcações sociais e simbólicas concentradas nas transgressões e na “punição”.
Evaluación del perfil competencial de alumnos universitarios respecto a la educación tecnológica
Authors: Díaz María Dolores , Martín Jaime Juan Jesús
Published: January 2016

Los docentes deben hacer uso de las nuevas tecnología para poder realizar un trabajo eficaz en la actual sociedad, donde los procesos educativos están basados en una cada vez mayor cantidad de información y conocimientos.

La formación inicial de estos futuros docentes debe estar impregnada de experiencias enriquecidas con las tic.

El estudio que se ofrece a continuación pretende conocer y analizar la percepción del alumnado de la Facultad de Ciencias de la Educación de la Universidad de Málaga  en relación con la adquisición de las competencias profesionales, referentes a las nuevas tecnologías, necesarias para el desempeño laboral de su profesión.

La investigación es descriptiva y la recogida de información se realiza a través de un cuestionario online realizado y validado previamente para los alumnos de los distintos estudios de grado, licenciaturas y Másteres Oficiales de Postgrado de  Ciencias de la Educación.
Los datos y resultados obtenidos son relevantes para determinar nuevas estrategias que permitan la adecuación entre las demandas laborales y la formación académico-profesional adquirida durante los estudios universitarios
Stress Re-orientation Analysis in Cupiagua Field
Authors: Alzate G. A. , Naranjo A. , Arbelaez A. , Arias J. A. , Araujo E. F. , Zabala R. D.
Published: January 2016

Hydraulic fracturing is a well stimulation operation which is done with the purpose to increase the production of oil wells, and due to its associated high costs a preliminary evaluation using computational methods is required. Carrying out a hydraulically fracture in previously fractured wells could represent several benefits if the new fracture propagates towards different direction than the first did, thus the fracture can reach and drainage new regions in the reservoir.

The success of these operations depends on the behavior of the horizontal stresses, because they are the ones that determine the orientation and the geometry of the hydraulic fracture, the fluid production and injection that take place within both operations alter the stress state.

This paper shows the mathematical analysis developed to model the horizontal stress reorientation and the conditioning of a coupled geomechanics-flow numerical simulator to calculate the angle of reorientation, and the results obtained using the data of two wells located in Cupiagua field, Colombia.
Spare Parts Strategy Based on RAM Analysis to Extend the Life of Drilling Supervisory and Control Systems: A Case Study
Authors: Cao Dingzhou , Moralez Nathan
Published: January 2016

This paper provides a case study on the application of Reliability, Availablity and Maintainability (RAM) analysis of a control system to determine the required number of spare parts to maintain and extend the life of the existing systems. As components within the Drilling Supervisory and Control System (DSCS) become obsolete or near obsolescence, different approaches are leveraged to retain system availability. Common practice is to replace the entire DSCS, thus eliminating obsolescence. An alternative solution is to employ a spare part strategy based on quantitative analysis for the existing system to prolong its life. This technique can be used to ensure that the control system continues to perform safe, compliant and reliable operations while realizing savings. Based on this study, the upgrade of five DSCS systems (offshore rig) was postponed realizing savings ($12 million) which approximated 95% of the total upgrade cost ($12.7 million). Furthermore, if a gradual upgrade strategy is adopted after 3 years, theoretically the system upgrade and the upgrade cost can be spread over 20 years while maintaining acceptable system availability.
New Approach In Lifting Cement In Highly Depleted And Naturally Fractured Formations
Authors: Diarra R. , Carrasquilla J. , Phelan D. , De Napoli Flensborg R. A.
Published: January 2016

Lost circulation is a continual problem associated while drilling and cementing during well construction. The failure to provide adequate cement coverage over loss zones can result in costly remediation and/or fines from regulatory agencies. Traditional losses prior to, or during, cement operations are addressed by loss circulation material (LCM) laden pills pumped ahead of the cement treatment as sweeps or spacers. The LCM pills are limited in volume to the size of the mixing tank and can be an insufficient volume compared to the thief zones. The high concentration of LCM in the pill results in higher rheology and can be difficult to properly displace up the annulus by the cement treatment due to inverse friction hierarchy between fluids. The solution being presented consists of using the cement slurry as the carrying fluid along with an inert engineered solid package. A fiber added on-the-fly improves the plugging efficiency of the engineered solid package and the ability to tailor the treatment design to the well conditions up until the treatment is pumped.

The results are tangible, with the solution applied successfully in over 300 treatments for multiple operators in the Permian Basin. The Permian Basin is one of the most developed basins in the world with a complex lithology and layered, highly depleted reservoirs. The solution successful performance has been unprecedented in allowing operators to comply with local regulations, avoid remedial work, and extend the life of the completion across corrosive formations. Application of the engineered solid package with fiber is for loss circulation cases in highly depleted zones, permeable formations, and naturally fracture formations for other basins. The progress thus far has been encouraging with additional optimization of the engineered solid package with fiber application could potentially improve the performance further. The final result will be an improved fluid placement and understanding of the effect LCM has on the carrying fluid.
Development of Geopolymer-based Cement Slurries with Enhanced Thickening Time, Compressive and Shear Bond Strength and Durability
Authors: Salehi S.. , Khattak M. J. , Ali N.. , Rizvi H. R.
Published: January 2016

Previous research on application of geopolymers in oil/gas wells was mainly unsuccessful due to failure to achieve a reasonable thickening time. The study here presents geopolymer slurries that have high compressive and shear bond strength, enhanced thickening time and high durability. Slurries developed in this work show durability when prone to sulphate/chloride or any other acid attack that might be encountered during cementing operations. Class F fly ash geopolymers were used for developing samples with different mix designs in this work. Class H Portland cement was used a controller on all the tests conducted in this work. Tests conducted in this research include Unconfined Compressive Strength (UCS), shear bond strength, thickening time and durability tests. Results indicate temperature as crucial factor affecting thickening time of Geopolymer mix slurry. More than four hours thickening time was achieved by optimizing mix design and application of developed mix of superplactisizer and retarder. UCS testing indicates a high compressive strength after one and fourteen days of curing for Geopolymer mixtures. This indicates gaining strength with time for Geopolymer mixture where time retrogression effects are observed for Portland cements. Results also indicate higher shear bond strength for Geopolymer mix which can better tolerate de-bonding issues. Additionally, more ductile material behavior and higher fracture toughness were observed for optimum geopolymer mixes. Final observations confirm applicability of these materials for oil and gas well cementing with circulating temperatures up to 250° F. These mixtures also show very good durability when compared with Portland cement mixtures. Higher durability will facilitate application of these materials for HPHT and corrosive wells where Portland cement shows poor performance.

Based on results from this study, Geopolymer mixtures show potentials for replacing Portland cement if they can be successfully tested in field applications. These materials can be produced cheaper with less environmental impact. The tangible benefits of the new products would be cost saving on well construction materials for operators with achieving long-time wellbore integrity goals and meeting regulators criteria for zonal isolation.
What Causes Depth Errors in Surface-Based Drilling Sensor Systems?
Authors: Lai Stephen W. , Pawson Mark , Wang Julian , Mukanov Nurlan , Wilson Tom , Dansereau Vincent
Published: January 2016

Drill string depth is a fundamental measurement performed by surface sensor systems. However, the depth reading on an electronic drilling recorder (EDR) often diverges from the pipe tally and requires periodic adjustment to remain aligned with the pipe tally total. In this paper, we investigate what causes depth errors and quantify the error magnitude in land-based wells. The main results show that the depth adjustment workflow varies significantly from driller-to-driller, and workflow errors are a major contributor to total depth error.

The investigation is performed with two main efforts. First, depth error is characterized by analyzing the corrections made to EDR depth in 29 onshore wells. Scatterplot analysis reveals that errors can be broadly classified into 3 main types: offset errors, accumulation errors, and workflow errors. Workflow errors can be further categorized into 7 subtypes. Statistical analysis of correction data shows that 75% of depth corrections are caused by offset and accumulation errors. However, workflow errors, such as human error and casing error, account for over 50% of depth corrections when measured on a per-footage basis. In the second effort, a user experience study is conducted to understand the depth correction workflow currently used by drillers. Interviews with 24 rig personnel reveal that workflows are not entirely consistent from driller-to-driller. Drillers tend to adopt the depth calibration methodologies taught by their mentors. A more consistent workflow is possible with increased training and a best practice guideline.
Downhole Drilling Dynamics of Innovative Rathole Elimination BHA in Hole-Enlargement-While-Drilling Operations
Authors: Wang Yaou , Fuller Nathan , Saheta Vishal
Published: January 2016

Hole enlargement while drilling (HEWD) is now widely used in deepwater applications. It provides reduced-clearance casing programs, improves drilling in swelling formations, and helps equivalent circulating density (ECD) management. HEWD applications commonly use an underreamer in a BHA with a rotary steerable system (RSS). Currently, traditional reamer placement results in a long portion of unenlarged hole—rathole—which requires an extra trip to enlarge. A new BHA design is being sought to eliminate the second trip requirement—the objective is to find a feasible solution.

Placing the reamer closer to the bit would forgo the need for a second trip; however, the placement of a traditional reamer is limited by its design. In response to such limitation, a solution is proposed to design a rathole elimination (RHE) BHA which includes a lower reamer placed between MWD/LWD tools and the RSS. During HEWD, the lower reamer is in passive (off) mode while a traditional reamer is active. Upon reaching TD, the BHA is tripped back to position the lower reamer above the rathole and is then activated to enlarge the rathole. This RHE BHA design thereby eliminates the second trip requirement.

This paper discusses the operational learnings and drilling performance of the proposed RHE BHA design. A field test in Texas is presented and documents the downhole dynamic performance of the single-trip BHA. Drilling dynamics measurement modules (DDMM) were positioned near the reamers to measure the downhole drilling dynamics. This run captured data for traditional HEWD operations and rathole elimination operations. To ensure stable drilling operations, a time-based dynamic simulation perfomed a prerun parametric sensitivity study to help identify the optimal parameters that could deliver high ROP, low vibration, and low stick-slip. A roadmap was made for operational guidelines based on simulation analysis. The test was successfully completed with stable HEWD and RHE operations observed. After completion of the run analysis of the DDMMs, measured downhole dynamic data showed stable downhole drilling dynamics during both HEWD and RHE operations. The RHE operation generated similar levels of vibration and stick-slip at the reamer and MWD/LWD tools compared with the HEWD operation. This field test shows that a single-BHA design can deliver stable drilling dynamics in both HEWD and RHE operations, and demonstrates the capability of the solution in eliminating the second trip requirement.

This single-trip RHE BHA design will not only reduce operational costs, but will also lower HSE risk by enabling less BHA handling on the rig floor.
Advanced Trajectory Computational Model Improves Calculated Borehole Positioning, Tortuosity and Rugosity
Authors: Abughaban Mahmoud F. , Bialecki Bernard , Eustes Alfred W. , de Wardt John P. , Mullin Steve
Published: January 2016

Wellbore tortuosity, defined as the degree of wellbore deviation from the smooth trajectory, and wellbore rugosity, defined as the degree of wellbore diameter irregularity, are critical elements in determining torque and drag (T&D) magnitudes in the drilling of long-reach horizontal wells and deep verticals. Current three-dimensional well trajectory models represented by the minimum curvature method (MCM) tends to mathematically smoothen the wellpath between survey-stations creating an artificially low tortuosity expressed as dogleg severity (DLS). This can lead to the miscalculation of the actual true vertical depth (TVD), leading to the underestimation of T&D magnitude. A robust three-dimensional trajectory model, the Advanced Spline-Curve (ASC) model, has been developed by the Colorado School of Mines to overcome these limitations. The ASC model provides realistic results and accurately calculate the spatial course of the wellpath.

The principal method proposed using the ASC model is a step toward more accurate representation of wellbore trajectories, as compared to other methods using constant curvature, minimum curvature or tangential calculations. This curve has continuous derivatives up to the third order (C3) along the entire wellpath. It is fairly straight-forward and has the robustness and flexibility to calculate complex, three-dimensional wellbore trajectories.

In this paper, various applications of the ASC model are presented and its results have been validated using two approaches: (a) an academic wellbore example of a known trajectory path, and (b) the use of high resolution continuous gyroscopic (HRCG) survey data recorded at one survey per foot. The calculated trajectory utilizing ASC model guarantees continuity along the entire wellpath with significant better accuracy as compared to MCM. These findings allow better wellbore positioning, more realistic tortuosity and the introduction of a rugosity measurement. This helps to evaluate drilling equipment and procedures while drilling highly deviated wells and extended verticals.

A HRCG survey recorded at one survey per foot provides a high level of wellbore positioning, tortuosity and rugosity accuracy; however, this is usually after the wellbore had been drilled and thus an improved calculation method such as the ASC model brings operational value.
Benefits of Using Downhole Vibratory Casing Tools in the Niobrara/Codell Formations
Authors: Warner Matthew , Hall Ryan A.
Published: January 2016

In recent years the construction of horizontally drilled wells has become commonplace. The horizontal sections of these wells have continued to increase in length as equipment and methods used in constructing these wells have improved. As lateral lengths have increased, so have the challenges associated with drilling and completing these wells. The high TMD/TVD ratios seen in many wells often presents challenges during the installation of casing and liners. The primary issue is the friction associated with horizontal well profiles and the absence of adequate vertical casing weight.

In order to combat the problems associated with getting casing/liners to bottom, operators are increasingly using downhole vibratory tools to aid these operations. Vibratory downhole tools primarily help by breaking the static friction between the workstring and wellbore or casing. These tools are commonly used in horizontal well drilling operations but more recently these tools have also begun to be run on casing strings with great success.

In this paper, the results of field tests using a downhole vibratory casing tool on a group of wells in the Niobrara and Codell formations are presented. Eight (8) wells were considered during the study. A vibratory casing tool was run in four (4) wells. Casing was run in four (4) additional wells in which no vibratory tool was used. The wells involved in the testing were completed with 4-1/2″ 13.5# P-110 liner in 2-section laterals. Evaluation of the data shows a 121% average increase in running speed while rotating the liner in the hole when using the vibratory casing tool, resulting in an average of a 23 hour (55%) decrease of rig time per run. Additionally, less torque at higher rotary speeds was seen on the wells in which the vibratory tool was run. The associated physics, operating methodology and effectiveness of these tools will also be presented.
Planning, Collaboration and Optimized Drilling Performance for Drilling Extended Reach Wells in the Bakken/Three Forks
Authors: Nair Vakkeyil Naveen , Bitzan Paul , McRobbie Neil
Published: January 2016

This paper discusses the methodology involved in evaluating the risks associated with drilling extended-reach wells using conventional drilling tools and adopting a stepped approach towards the drilling optimization of 25,000-ft total depth wells, with horizontal legs exceeding 14,000 ft. Extensive planning was carried out over the following areas of the project: well-trajectory design, torque and drag, the fluid program, drilling practices, drillstring design and integrity, hydraulics management, drilling optimization tools, and bottomhole assembly (BHA) design.

The objective was to drill two horizontal wells in the Bakken and Three Forks formations in North Dakota and to use the lessons learned to drill three extended-reach wells with 50% percent longer laterals. The first two wells of the project were studied to calibrate torque-and-drag models for hole friction, drillstring dynamics with the effects of fluid in-hole drag, effects on rate of penetration with regards to weight transfer while sliding, hydraulic effects of the fluid system, motor output, vibrations analysis, drilling practices through transitions, and parameter optimization while drilling through formation markers through the horizontal leg of the well.

The first two wells were drilled using a drilling-optimization downhole tool placed above the motor that measures the weight, torque, and bending moment across the sub. The pressure-while-drilling tool was also used. Tri-axial vibration sensors were used to measure and transmit data in real time to optimize drillstring dynamics and make improvements in the drilling system post run. The improvements in the system and lessons learned were used for three additional extended-reach wells with measured depths over 25,000 ft. Drillstring dynamics from the downhole sub were studied to identify ways to overcome friction. The data validated the effectiveness of certain friction-breaking tools and proposed areas for improvement to orient drill with conventional motors further into the lateral. The limitations with the current system were identified with the first two horizontal wells. Wellbore-trajectory design and pipe placement were optimized to aid in transferring weight to the bit beyond the 10,000-ft lateral horizontal leg. Alterations in the drilling program were subsequently made to drill further into the lateral based on lessons learned from downhole optimization tools and surface sensor data.

Three wells were drilled beyond a 25,000-ft total measured depth, with the horizontal leg exceeding 14,500 ft in the lateral. Continuous improvements were made to the system to drill to the limit with conventional motors and to pick up sophisticated rotary steerable tools to drill the last 1,500 ft of the lateral. The approach proved more cost effective to optimize within the constraints of the drilling system before using sophisticated rotary steerable tools.
Modeling and Simulation of Annular Pressure Buildup (APB) Mitigation Using Rupture Disk
Authors: Liu Zhengchun , Samuel Robello , Gonzales Adolfo , Kang Yongfeng
Published: January 2016

Manufactured to burst/collapse at a specific pressure difference and installed in the casing wall, a rupture disk is a common device used to mitigate annular pressure buildup (APB) and to protect casing strings. This paper focuses on the modeling and simulation of the effects of a rupture disk burst/collapse event on APB in casing/tubing annuli.

After the rupture disk bursts (or collapses), fluid will move through the open disk from one annulus to another, resulting in changing pressures. In this work, three pressure balance models (piston model, miscible fluid model, and immiscible fluid model) were established to calculate the annulus fluid pressure and volume changes after the rupture disk opens. The piston model, assuming no fluid exchange between two annuli, provides the simplest solution. It is accurate if the two annuli contain nearly identical fluids. The miscible fluid model is intended for annuli with the same fluid type, but with different density values. The immiscible fluid model is intended for annuli with different immiscible fluid types, such as oil-based mud in the internal annulus and water-based mud in the outer annulus.

The pressure balance models were implemented and integrated into a commercial casing and tubing design software platform. A numerical approach was used for trapped and connected annuli; an analytical approach was used for connected annuli with at least one ventilation or leakoff point. This combination provides optimized simulation performance and accuracy. When multiple annuli are connected with open rupture disks, global pressure equilibrium is reached through iterations of handling two connected APB regions at a time.

In a case study in which the casing ballooning effect is negligible, numerical simulation results were found to be consistent with the results of analytical calculation; the difference is within 0.1%. The application of the rupture disk for APB management was also demonstrated in another case study using field data. The simulation results show that the rupture disk is a viable and cost-effective option for APB management.
A Step Change in Drill Bit Technology with Self-Adjusting PDC Bits
Authors: Jain Jayesh R. , Ricks Gregory , Baxter Benjamin , Vempati Chaitanya , Peters Volker , Bilen Juan-Miguel , Spencer Reed , Stibbe Holger
Published: January 2016

Since they were first introduced to the market decades ago, polycrystalline diamond compact (PDC) bits have undergone numerous technological improvements. One such example is depth-of-cut (DOC) control technology. Introduced in early 2000s, this technology emerged as an effective means to mitigate torsional vibrations by managing bit aggressiveness. Today, however, the drilling industry faces the task of drilling diverse sections of the well with a single bit. This is a significant challenge for fixed PDC bits, requiring a compromise that limits vibration mitigation in some sections of the well and/or top-end rate of penetration (ROP) performance in other sections.

This paper presents an innovative PDC bit that can self-adjust its DOC control characteristics to the constantly-changing drilling environment and mitigate vibrations while delivering improved ROP. The self-adaptation is accomplished through a passive hydro-mechanical feedback mechanism encapsulated in self-contained cartridges that are installed inside the bit blades. The DOC control elements mounted on the cartridges respond to the external loads through strategically designed rate-sensitive retraction and extension strokes. During unfavorable dynamic events, the elements engage with the formation and mitigate dysfunctions. During normal steady-state drilling, the elements gradually adjust their exposure to enable fast and efficient drilling.

The operating principle of self-adjusting PDC bits is first demonstrated through laboratory drilling tests under confining pressure using full-scale prototype bits. The testing was expanded to research wells in the field to assess the ability to self-adapt and mitigate stick/slip vibrations. The field test facility enables a controlled yet realistic environment with reduced uncertainty that is often not available in the field. The tests compare stick/slip tendencies of bits by building stability maps in WOB-RPM space using downhole measurements under similar operating conditions. Bits with the self-adjusting mechanism led to fewer instances of stick/slip than fixed PDC bits in multiple formation types. Self-adjusting bits significantly expanded the stable operating region and enabled operation at higher ROP.

The ability of the DOC control elements to continuously self-adjust their exposure overcomes several other limitations posed by the fixed nature of traditional DOC control. The technology doesn't require a fixed pre-designed exposure, prevents over-engagement because of its ability to retract, and eliminates iterative tuning of DOC control currently in practice. The technology is also anticipated to absorb impacts in interbedded formations and reduce damage from improper starting procedures. With many PDC bit drilling applications being torque-limited, the technology opens up several possibilities to reduce drilling costs.
Improvements in the Root Cause Analysis of Drillstring Vibration
Authors: Greenwood Jeremy A.
Published: January 2016

Drillstring vibration is a leading cause of downhole tool failure and premature wear of downhole equipment. The main challenges faced during drilling include performing rapid analyses to determine the root cause of the vibration, clear identification of the active mechanism, and implementation of the appropriate corrective action quickly enough to prevent failure. This paper describes a comprehensive methodology created to identify root causes, all vibration mechanisms, and methods to reduce or eliminate drillstring vibration on a range of different operations.

A BHA and drillstring have six degrees of freedom and three dominant modes of vibration: axial, lateral, and torsional. This movement is used to describe the different vibration mechanisms, such as stick/slip, bit bounce, bit whirl, BHA whirl both forward and backward, torsional resonance, bit chatter, modal coupling, and lateral shocks. Data is collected from downhole and surface sensors, as well as cutting analyses that measure modes and magnitudes of vibration, tension, compression and bending within the (BHA), drilling parameters, fluid properties, and lithology and rock properties. The methodology uses some or all of these factors to identify the root cause and is enhanced by the ability to summarize the distribution of vibration levels across a run, histogram analysis, and the ability to filter across time or depth ranges and further filter based on rig-activity codes.

There is a combination of factors that generate or influence drillstring vibration, including the energy inputs of weight on bit (WOB) and torque (TRQ), bit type, BHA design and stabilization, lithology type, geological structures, bit-lithology interaction, borehole size and BHA size, hole trajectory, backreaming or rotating off bottom, hole enlargement, the rig's electrical system, and on offshore floating vessels, rig heave.

The methodology is able to identify and isolate which factors are the root cause of a specific mechanism by incorporating time-based analyses with depth-based logs and plotting a to-scale BHA to identify correlations of the bit position, stabilizer, and other BHA components to formation types and boundaries, hole-size changes, and casing positions. This enables a significantly faster data analysis and a more rapid assessment of the root cause of the vibration, thereby delivering specific benefits through identifying and then reducing or eliminating drillstring vibration on a range of different operations.