bluuebunny/crossref_metadata_2025 huggingface dataset:
'Do We Really Need to Know This?' The challenge of developing a global learning module for trainee teachers
Authors: Scoffham Stephen
Published: September 2016

This article explores some of the challenges of developing a module on global learning with primary initial teacher education (ITE) students studying at a UK university. The research, which employed a mixed methodology, involved around 550 students and eight members of staff over a
three-year period. The findings indicate that many students developed their thinking about global issues, albeit on a surface level. A small but significant minority proved much harder to reach. The discussion highlights the complexities of global learning, the significance of underlying values
and beliefs, and the impact of the wider professional and cultural context. A key issue that emerges is the importance of recognizing barriers and inhibitors to global learning.
Fair-Minded Critical Thinking in Development Education: Reflections on pedagogies for transformation
Authors: Brown Eleanor J.
Published: September 2016

This article discusses research with development education practitioners in Britain and Spain, to explore their conceptions of pedagogical approaches to development education and how these relate to transformative learning theory. Development education is a process designed to generate
informed action, which implies the objective of transformation through learning. By considering two key concepts of transformative learning theory – critical reflection and dialogue – the aim of this article is to analyse how practitioners understand and facilitate these through
development education.
World Society and the Human Being The possibilities and limitations of global learning in dealing with change
Authors: Lang-Wojtasik Gregor
Published: September 2016

This article deals with understandings of change. It attempts to provide a framework for comprehending the hopes and assumptions concerning change that are implicit within global learning. The proposed framework of understanding draws on the theoretical perspectives of 'world society'
(Luhmann) and 'homo absconditus' (Plessner), and therefore places the proposed framework regarding an understanding of change within the context of an understanding of cultural functionality.
Global citizenship in Pakistan
Authors: Pasha Aamna
Published: September 2016

This paper attempts to understand the value of the ideology of global citizenship in Pakistan by looking at students' values and attitudes. In particular, it explores students' understanding of the term 'global citizen' and their attitude towards the concept. Using a case study approach,
interviews were conducted with six students in a privately run school under the national education system, in addition to five teachers who have undergone a global citizenship training. This research highlights students' strong national identity, which engenders a sense of urgency with regard
to displaying a positive side of the country, with global citizenship being seen as one avenue for creating a positive image. In addition, the absence of a clear understanding of 'citizenship' itself means a very loose understanding of what global citizenship could or should entail. These
findings communicate the need to rethink global citizenship in the Pakistani context through a redefinition of the concepts from a local perspective.
Linking participatory action research, global education, and social justice: Emerging issues from practice
Authors: Kaukko Mervi , Fertig Michael
Published: September 2016

This article focuses on the practical, ontological, and epistemological similarities and differences between global education and participatory action research (PAR). The paper starts by presenting classical definitions of action research, highlighting their similarities with the ideas
of global education. Considering the aim of global education is to promote social justice and to improve the social and educational chances of groups at risk of marginalization, participatory methods can help to involve such groups in research in an ethical and effective way. The paper ends
with two examples in formal and non-formal education that show that PAR can be used to address the underlying transformative and social action principles of global education, but the principles must be adjusted to meet the needs of the participants and the context.
Global education and the cooperation of NGOs and schools: A German case study
Authors: Bergmüller Claudia
Published: September 2016

In recent years, there has been growing pressure but also an increase of possibilities for non-governmental organizations (NGOs) to cooperate with schools in the field of global education. However, especially in cases of more continuous forms of cooperation, difficulties in process
management are noted and the intended cooperation impacts often seem to lag far behind expectations. This paper uses an empirical case study that evaluated the effects of a three and-a-half-year NGO–school cooperation on the school-internal implementation of global education to give
explanations for the occurrence of such difficulties and suggest ways to support the implementation of global education via NGO–school cooperation. Against this background, the role(s) of NGOs as stakeholders for global education in the school sector will be explored.
Pediatric Multiple Sclerosis in Portugal: A Multicentre Study
Authors: Correia Ana Sofia , Augusto Luís , Meireles Joana , Pinto Joana , Sousa Ana Paula
Published: September 2016

Introduction: Multiple sclerosis is most often diagnosed among young adults but less frequently it may present during childhood or adolescence. In Portugal, there has been only one previous single-center, pediatric multiple sclerosis study. The main objective was the evaluation of the demographic, clinical, laboratorial and neuroradiological characteristics of patients with pediatric-onset multiple sclerosis in Portugal. The secondary objectives were to compare the characteristics of childhood-onset multiple sclerosis and adolescent-onset multiple sclerosis and to characterize the treatments prescribed.Material and Methods: We performed a retrospective observational, multicentric study. We reviewed data of all patients with multiple sclerosis younger than 18 years at the onset of their first multiple sclerosis symptoms.Results: There were 46 patients (72% female) included with a mean age at diagnosis of 16.1 years. Six cases had childhood-onset and 40 cases had adolescence-onset. The median value of Expanded Disability Status Scale was two. Relapsing-remitting multiple sclerosis was most prevalent (98% of cases). In the cerebrospinal fluid study, 74% of patients had positive oligoclonal bands. Brain magnetic resonance imaging studies showed a predominant supratentorial involvement (98% of cases), whereas the cervical segment was the most frequently affected in the spinal cord. All the patients enrolled in the study underwent immunomodulatory therapy, 75% ofpatients with beta-interferon. Concerning differences between the childhood and the adolescent groups, we found a greater proportion of male patients and of individuals with cerebrospinal fluid pleocytosis among the childhood-onset group.Discussion: This study provides new data on pediatric multiple sclerosis characteristics in Portugal and our results are similar to previously reported data in other parts of the worldConclusion: This is the first multicentric study characterizing pediatric multiple sclerosis in Portugal. The mechanisms underlying the particularities of pediatric multiple sclerosis remain largely unknown and further studies are required.
Short and Long-Term Efficacy of Laparoscopic Ovarian Diathermy in Women with Polycystic Ovary Syndrome
Authors: Luz Rita , Barros Joana , Aguiar Ana , Rodrigues Cátia , Soares Ana Paula , Nunes Joaquim , Sousa Sandra , Calhaz-Jorge Carlos
Published: September 2016

Introduction: Polycystic ovary syndrome is the most frequent cause of anovulatory infertility and management involves a multistep approach. Laparoscopic ovarian diathermy is accepted as a second-line treatment of patients who failed to respond to clomiphene citrate. The aims of this study were to determine the efficacy of this technique at short and long-term and to perform an analysis of predictive factors of spontaneous pregnancy.Material and Methods: This retrospective study involved 76 women who underwent laparoscopic ovarian diathermy between 2004 and 2013 in a university hospital. Main outcomes were cycle regularity and pregnancy. Short-term outcomes recorded during followup in our centre were reviewed and long-term outcomes were evaluated by a telephone interview to all women whose surgery was undertaken more than three years ago. Clinical and biochemical data were analysed as predictive factors of spontaneous conceptionin patients without other infertility factors.Results: Menstrual cycle regularity was initially achieved in 53 (70%) women and in the long-term follow-up subgroup, 52% (12/23) had regular periods. In general, 53 (70%) women conceived and 77 pregnancies were achieved, 60% of which were spontaneous. The only prognostic factor found to be significantly associated with spontaneous conception was a shorter duration of infertility (< 3 years) (p < 0.05).Discussion: Laparoscopic ovarian diathermy showed pregnancy rates comparable to other ovulation induction treatments with the advantage of having a long lasting beneficial effect in menstrual regularity and fertility.Conclusion: Laparoscopic ovarian diathermy is a safe and effective treatment option for anovulatory infertility in women with polycystic ovary syndrome.
Mecanismos Moleculares de Adesão e Colonização da Mucosa Gástrica pela Helicobacter pylori e suas Implicações Clínicas
Authors: Coelho Elisabete , Magalhães Ana , Dinis-Ribeiro Mário , Reis Celso A.
Published: September 2016

Introdução: A infeção por Helicobacter pylori é muito prevalente mundialmente, e está associada à progressão da cascata de carcinogénese gástrica, sendo um dos principais fatores de risco para o desenvolvimento de carcinoma gástrico. São vários os fatores determinantes para a infeção e desenvolvimento de patologia gástrica, incluindo fatores ambientais, fatores genéticos do hospedeiro, e fatores de virulência da bactéria.Material e Métodos: Neste trabalho, é apresentada uma revisão do estado da arte sobre os fatores determinantes da infeção e sobre os mecanismos moleculares de adesão da Helicobacter pylori à mucosa gástrica recentemente descritos e a sua possível aplicação terapêutica.Resultados: A adesão da Helicobacter pylori ao epitélio gástrico é uma etapa fundamental da patogénese gástrica, permitindo o acesso da bactéria a nutrientes, e a ação de diversos fatores de virulência da bactéria, promovendo, desta forma, a recorrência da infeção e a progressão na cascata de carcinogénese gástrica.Discussão: A erradicação da infeção por Helicobacter pylori é a melhor estratégia preventiva disponível contra o carcinoma gástrico, principalmente quando feita antes do aparecimento de lesões pré-neoplásicas. O aumento da resistência aos antibacterianos e as taxas de erradicação, por vezes aquém do esperado, contribuem para a procura de alternativas de tratamento.Conclusão: O desenvolvimento de novas estratégias terapêuticas focadas nos mecanismos moleculares de adesão da Helicobacter pylori é muito promissor, no entanto são necessários estudos futuros sobre a sua eficácia in vivo e toxicidade.
Errata ao Artigo “Burnout em Profissionais da Saúde Portugueses: Uma Análise a Nível Nacional”
Authors: . .
Published: September 2016

Errata ao artigo “Burnout em Profissionais da Saúde Portugueses: Uma Análise a Nível Nacional”, de João Marôco, Ana Lúcia Marôco, Ema Leite, Cristina Bastos, Maria José Vazão, Juliana Campos (Acta Med Port. 2016;29:24-30).
Transcriptome Analysis Identities Key Candidate Genes Mediating Purple Ovary Coloration in Asiatic Hybrid Lilies
Authors: Xu Leifeng , Yang Panpan , Yuan Suxia , Feng Yayan , Xu Hua , Cao Yuwei , Ming Jun
Published: September 2016

Lily tepals have a short lifespan. Once the tepals senesce, the ornamental value of the flower is lost. Some cultivars have attractive purple ovaries and fruits which greatly enhance the ornamental value of Asiatic hybrid lilies. However, little is known about the molecular mechanisms of anthocyanin biosynthesis in Asiatic hybrid lily ovaries. To investigate the transcriptional network that governs purple ovary coloration in Asiatic hybrid lilies, we obtained transcriptome data from green ovaries (S1) and purple ovaries (S2) of Asiatic ‘Tiny Padhye’. Comparative transcriptome analysis revealed 4228 differentially expressed genes. Differential expression analysis revealed that nine unigenes including four CHS genes, one CHI gene, one F3H gene, one F3′H gene, one DFR gene, and one UFGT gene were significantly up-regulated in purple ovaries. One MYB gene, LhMYB12-Lat, was identified as a key transcription factor determining the distribution of anthocyanins in Asiatic hybrid lily ovaries. Further qPCR results showed unigenes related to anthocyanin biosynthesis were highly expressed in purple ovaries of Asiatic ‘Tiny Padhye’ at stages 2 and 3, while they showed an extremely low level of expression in ovaries of Asiatic ‘Yellow Pixels’ during all developmental stages. In addition, shading treatment significantly decreased pigment accumulation by suppressing the expression of several unigenes related to anthocyanin biosynthesis in ovaries of Asiatic ‘Tiny Padhye’. These results could further our understanding of the molecular mechanisms of anthocyanin biosynthesis in Asiatic hybrid lily ovaries.
Tea Polysaccharides and Their Bioactivities
Authors: Du Ling-Ling , Fu Qiu-Yue , Xiang Li-Ping , Zheng Xin-Qiang , Lu Jian-Liang , Ye Jian-Hui , Li Qing-Sheng , Polito Curt Anthony , Liang Yue-Rong
Published: September 2016

Tea (Camellia sinenesis) is a health beneficial beverage and is also a source for extracting bioactive components such as theanine, tea polyphenols (TPP) and tea polysaccharides (TPS). TPS is a group of hetero-polysaccharides bounded with proteins. There were tests showing that TPS had various bioactivities, such as antioxidant, antitumors, antihyperglycemia, anti-inflammation and improving immunity. However, inconsistent results concerning chemical composition and bioactivity of TPS were published in recent years. The advances in chemical composition and bioactivities of TPS were reviewed in the present paper. The inconsistent and controversial results regarding composition and bioactivities of TPS were also discussed.
Anticancer and Antioxidant Activities of Some Algae from Western Libyan Coast
Authors: Alghazeer Rabia , Enaeli Mahboba , Howell Nazlin K.
Published: September 2016

Seaweeds are considered as one of the largest biomass producers in marine environment that is rich in bioactive metabolites and a source of natural ingredients for functional foods. The potential antioxidant activity and the potential inhibition of Caco2 cell proliferation, of crude extracts of: Chlorophyta (Ulva lactuca, and Codium tomentosum), Phaeophyta (Cystoseira crinita, Cystoseira stricta, and Sargassum vulgare), and Rhodophyta (Gelidium latifolium, Hypnea musciformis, and Jania rubens) collected from western Libyan coast were evaluated in vitro. The antioxidant activity was determined by reducing power and DPPH assays while cell proliferation, morphological changes and the cell cycle arrest were assessed by MTT, inverted light microscope and flow cytometry methods respectively. The polyphenols and flavonoids rich extracts showed remarkable reducing power and antiradical properties. After exposure of Caco2 cells to; various concentrations of extracts (50, 100,150 and 200 µg/mL) especially from brown algae for 72 h, significantly reduced cell proliferation. The antiproliferative effect of algae extracts was correlated with their polyphenol and flavonoid contents. Cell cycle analysis further showed that cells were arrested in G phases along with an increment in sub-diploidal cell population (sub-G) after extract application. These results imply that seaweeds which are rich in bioactive compounds may be in anticancer drug research programs. However, further investigations are essential to reveal the molecular mechanisms of the anticancer activities of these algae.
Intervention-Less Multi-Zone Lower Completion Tools – A Case Study
Authors: Murdoch Euan , Robertson Bruce , Munro Christopher , Edwards Andrew , Ghaempanah Babak , Loonstra Cornelis , Kimmitt Kyle , Rahman Shamsur , Bakker Eelco
Published: September 2016

Driven by ever increasing associated costs, the industry has long sought an enabling technology to expedite hydraulic fracture cycle times in high cost environments such as offshore. Remotely operated completion tools have been proven to provide these efficiencies and can positively influence the viability of these multi-zone stimulation projects.

This paper will focus on the planning and execution of a recently completed offshore North Sea lower completion to present a methodology to remotely access and isolate the reservoir during multi-zone stimulation operations. Innovative technologies utilized in this case study are presented which effectively minimize the cycle time of the stimulation process while providing a high level of contingencies to account for a panoply of scenarios which could occur through-out the operation.

There are several techniques and methodologies which have been deployed to efficiently stimulate multi-zone, horizontal wells in offshore locations such as those found in the North Sea; technical papers such as (Langford 2014) discuss these in detail. This paper will describe the successful deployment of a novel lower completion system into a Southern North Sea extended reach well in June 2015 which targeted the a sandstone formation of the Lower Permian (Rotliegend) strata.

The selected remotely operated lower completion system incorporates multiple communication methods on-board to permit remote functioning of flapper isolation valves, to compartmentalize the reservoir internally, and remote operated stimulation sleeves to access the reservoir, which effectively eliminates the need for intervention between treatments, ultimately improving fracture cycle time and reducing risk while providing operators with realistic contingencies in the event of screen-out.
A Direct Method for Stratigraphically Consistent Assisted History Matching of Object-Based Geomodels – Algorithm and Field Application
Authors: Alpak Faruk O. , Jennings James W. , Gelderblom Paul , Chen Chaohui , Gao Guohua , Du Kuifu
Published: September 2016

Object-based static models are typically constructed for stratigraphically complex reservoirs. In this approach, the stratigraphic architecture is represented by use of distinct objects with specific geometric attributes and petrophysical characteristics. It is a major challenge to condition such models to production data while simultaneously maintaining the geologic realism and static conditioning.

A novel workflow is developed for the Assisted History Matching (AHM) of object-based geomodels where the uncertain object locations and attributes are directly modified without resorting to (post-geomodeling) reparameterization techniques. It contains an object modeling algorithm for channels and levees that provides direct access to the pre-raster geomodeling parameters for individual object locations and attributes. These parameters are gradually modified subject to physical constraints to achieve a history match. A fully integrated protocol is employed in this process that automatically couples the static modeling algorithm with the reservoir simulator. The resulting workflow is moderated by a massively parallel and highly efficient iterative data-integration algorithm. In the AHM workflow, static and dynamic conditioning operations are respectively driven by separate objective functions and are performed at the iteration level in a sequential fashion. The static conditioning step may add and remove objects in the geomodel, which changes the number of active AHM parameters over the course of the iterative search. The workflow handles such operations with minimal impact on the robustness of the search.

A potential application of the direct AHM workflow for object-based geomodels is the identification of locations and attributes of channels in deepwater turbidite reservoirs, where the channels are typically below the resolution of the seismic data; the well spacing is typically larger than the characteristic object dimension, yet the production data exhibit strong sensitivity to channel connectivity. The concept of gradually adjusting the channel locations by using the information in the production data (while maintaining static conditioning) is demonstrated on a real dataset for a deepwater channelized-turbidite reservoir. The models proposed by the new AHM workflow not only improve the difficult-to-history-match injected gas breakthrough profiles but also provide geologically based explanations for them, taking into account the channel connectivity. The proposed AHM workflow ensures consistency across static and dynamic models by integrating multi-disciplinary data with an easily auditable and replicable capability.
Big Data Yields Completion Optimization: Using Drilling Data to Optimize Completion Efficiency in a Low Permeability Formation
Authors: Lehman Lyle V. , Jackson Kale , Noblett Bruce
Published: September 2016

Poor production results in the subject area was determined to be caused by poor reservoir contact along the laterals. In a series of wells using multi-stage plug-and-perf completions, poor perforation efficiency was diagnosed. A solution to improve formation contact was employed which made absolute contact with the reservoir by using sliding sleeves and coil tubing technology. However this system demonstrated issues mainly around lower estimated ultimate recovery (EUR) values due to wide fracture spacing limitations and also suffered occasional human related, not tool quality, failures which caused costly penalties in completing wells. Returning back to the original completion scheme re-presented the original problem that very few of the perforation clusters were opening and thus using plug-and-perf and also obtaining better perforation efficiency was re-sought.

This solution step developed in this paper uses drilling data which through the use of neural networks, can generate a synthetic log. The log can yield rock properties which can generate stresses along the wellbore. These stresses are then used to select perforation spacing to better take advantage of ‘like’ stresses so that perforation opening can improve. Minimum pressure drops between perforations can then be designed. Additional information pertaining to reservoir quality was generated by adding gas chromatograph data to determine the highest permeability sections of the lateral as well as the liquid-rich hydrocarbon bearing sections. This analysis allows for a solution matrix of job and cluster spacing types to optimize fracture spacing (frequency of contact) and conductivity requirements to optimize the completion based on stress and relative or contrasting permeability.

This paper will demonstrate how the problem was determined, the solution was implemented, how some alternatives were explored and how fracture geometry was greatly improved using these workflows.
Successful Development and Implementation of 9 5/8 Subsurface Safety Valve for High Pressure, High Rate Gas Wells
Authors: Al-Muslim Ali , Al-Yateem Karam , Nafa Hamed , Swan Thomas , Abdelhamid Amr
Published: September 2016

Because the need for energy is increasing worldwide, new technologies must emerge to accommodate this increase. In the Kingdom of Saudi Arabia, supplying natural gas to satisfy local energy demand presents a large challenge. When offshore high pressure and high temperature (HPHT) gas fields, Hasbah and Arabiyah, were under development, this local high demand and the means to fulfill it had to be considered. One of the necessities associated with safety and involving the greatest possible gain was the idea of the 9 5/8-in. big bore completion. The combination of size and rating (9 5/8 in. completion equipment rated for 10,000 psi) was not available in the market at that time; consequently, it had to be developed specifically for this project. This paper discusses the development, testing, and qualification for a very important part in the well completion: the 9 5/8-in. 10,000 psi Tubing Retrievable Safety Valve (TRSV).
Leading Oil and Gas Into the Future
Authors: Babey Andrew G. , Hagel Nick , Montilla Carlos , Robins Ryan , Harris Craig
Published: September 2016

The oil and gas industry faces an impending and unprecedented labor gap that requires both short-term and long-term action by leaders. This paper examines the history and root causes of labor challenges in the industry, generational differences in the workforce, critical roles within oil and gas companies, ways of mitigating the immediate and future risk, and requirements for building and maintaining the workforce to achieve future success.

The volume of baby-boom retirements anticipated between 2011 and 2029 will create a labor scarcity that will impact all industries?none more than the oil and gas industry. Multiple factors are contributing to this situation. Most importantly, the volatility of our industry since the early 1980s has significantly diminished the talent pool, and succession planning has not been a priority. Generational differences within the workforce compound the problem but also offer unique opportunities for the future.

Like the major downturn of the 1980s, the current downturn has forced the industry to relinquish valuable skillsets in the short-term that will be required in the long-term. Moreover, the relatively few skilled workers from the 1980s era that remain to pass on their precious skillsets will be retiring at a rapid rate. The Big Crew Change is coming, and the industry is ill prepared because organizations have largely ignored the succession planning that is critical for future success.

Effective succession planning identifies positions that are critical to organization success and then plans accordingly to address them. In our industry, engineers, geologists, skilled laborers, and experienced executives are especially difficult roles to fill because the demand is high and there are fewer individuals with experience in these areas.

In any organization, the senior management team must drive succession planning, align it with the organizational culture and values, and enforce accountability for it throughout the organization. That may include different business models as well as new ways of making the oil and gas industry more attractive for younger generations who have different values, expectations, objectives, and work styles. New leaders will need to lead rather than direct, be adaptable and look at the world on a global scale, and have a high level of business acumen.
Assuring Optimum Production and Enhanced Operational Efficiency through Transient Simulation: A Case Study in North Kuwait Jurassic Fields
Authors: Al-Sharrad Mohammad , Prakash Roshan , Trudvang Christian. F. , Al-Mai Noura , Hajjeyah Abrar A. , Al-Failakawi Abdulaziz H.
Published: September 2016

The paper presents the flow assurance challenges and the mitigation steps taken in the deep, high pressure & high temperature North Kuwait Jurassic (NKJ) Fields. Flow assurance is extremely diverse subject linked to different engineering disciplines. Understanding the reservoir fluid behavior, rock minerals, completion & pipeline metallurgy and operating envelope is critical to understand and overcome the flow assurance challenges. Pipeline Hydrate Formation is the biggest operational challenge, which frequently disrupts the production of some of the high producing gas wells during the winter months. Different chemicals and combinations of such have been attempted to mitigate the hydrate problem, still optimization of the chemical injection process is ongoing. Other problems of solid, scale or salt blockage in the tubing, surface chokes and pipelines have occurred and steps were taken to clear the obstructions. The NKJ fluids are highly corrosive and a corrosion inhibitor is injected at the wellhead to protect the surface pipelines. Addressing all these challenges require thorough knowledge of the specialized subjects and advance modeling to improve the field operational philosophy.

In the NKJ fields, the pipeline connecting the well to the processing facility (5 – 30 Km long) are neither buried nor insulated. During the winter months (during night & early morning), the well fluid cools down below the hydrate formation temperature in the flowline causing hydrate crystallization and even plugging of the pipeline. Out of the 30 producing wells in the NKJ fields, half of the wells produce water and have hydrate tendency. The produced water salinity varies from well to well and range from fresh water to highly saline water with salinity as high as 330 kppm. This makes the system highly complex and manifest need for a robust solution.

The paper walks through the traditional methods of hydrate mitigation done in the NKJ fields and the way in which transient model was initially built and continuously improved with more data. Currently methanol is used as the hydrate inhibitor and an anti-agglomerate (AA) is under trial. The methanol concentration is governed mostly by experience and on a reactive mode.

An offline transient model advisor was built to understand the hydrate mechanism and optimize the methanol injection The advisor is still under trial, once simulation matches with the field conditions, then it will be online and linked to the existing KwIDF (Kuwait Integrated Digital Fields) technology program. Under KwIDF, Chemical Management workflow will be designed to optimize methanol injection to minimize the well downtime and reduce the OPEX cost. The transient advisor also can predict the surge at the facility inlet which can assist in balancing the production in and out of the facility.
Nanoparticles Adsorption, Straining and Detachment Behavior and its Effects on Permeability of Berea Cores: Analytical Model and Lab Experiments
Authors: Wang Wendong , Yuan Bin , Su Yuliang , Wang Kai , Jiang Miaolun , Moghanloo Rouzbeh Ghanbarnezhad , Rui Zhenhua
Published: September 2016

The aim of this paper is to present both experimental and theoretical investigations on nanofluid flow with dynamic adsorption, detachment and straining behavior, and its associated formation damage. In this paper, we conduct core-flooding experiments on oil-wet Berea sandstone. Hydrophilic Nano-structure particles (NSP) is dispersed in the injected brine stream at 0.05, 0.2 and 0.5wt% concentrations. During the core-flooding of nanoparticles injection and post-flush of brine, the corresponding pressure drops across the cores and the effluent nanoparticles concentration are recorded. In order to quantify nanoparticles adsorption/detachment and straining behavior and associated effects on fluid flow, an analytical model is derived using method of characteristics. The interplay between nanoparticles and rocks is described by the coupled the classical particles filtration theory and maximum adsorption concentration model. All the necessary parameters, i.e., the maximum adsorption concentration, reversible or detachment adsorption concentration, nanoparticles adsorption and straining rates, and the corresponding formation damage coefficients, are characterized by matching analytical solutions with the effluent nanoparticles concentration history and real-time pressure drop.

The experimental results indicated that both adsorption and straining occur during the injection. The extent of adsorption and straining for Nano-structure particles (NSP), i.e., maximum adsorption concentration, particles adsorption rate and straining rates, increases along with the increase of nanoparticles injection concentration. As the results, the breakthrough time of nanoparticles injection is delayed, the steady-state effluent concentration decreases, and the pressure drop increases more rapidly. The adsorption amount of nanoparticles includes the reversible and irreversible adsorption. During the post-flush of brine, the reversible adsorbed nanoparticles detach from the already adsorption layers. With the increase of nanoparticle injection concentration, the reversible or detachment of adsorbed nanoparticles also increase.

In practice, this paper will contribute for the following applications 1) apply lab experiments to highlight the importance of nanoparticles adsorption, straining and detachment behaviors on the formation damage. 2) The analytical solution provides physical insights to quantify nanofluid flow performance, and can also be used to optimize the usuage of nanofluids application while considering the loss caused nanoparticles adsorption and straining.
Underbalanced Coiled Tubing Mechanical De-Scaling Operations: A Case History for an Oil Well in Ghawar Field from Saudi Arabia
Authors: Alabdulmohsin Yousif A. , El-Zefzafy Ibrahim Mohamed , Al-Malki Mohammed H. , Al-Mulhim Abdullah A. , Al-Ramadhan Ali A. , Al Hamawi Kaisar , Arfin Mohammad , Ahmad Danish
Published: September 2016

Accumulation of hard scale in the production tubing will not only affect the well accessibility it will also lead to a dramatic decline in production rate and locking the allocated production. Maintaining wells accessibility to wellbore for well intervention operations in order to run logs, water shut-off jobs, well securement operation,…etc. is part of well integrity and performance assurance program. The traditional operation approaches in other areas and reservoirs include isolating the active reservoir prior to operations are not suitable for all cases especially when formation damage is expected to take place. The implementation of underbalance mechanical de-scaling operations using coiled tubing; will lead to restore wells to production faster, regain well productivity and avoids the formation isolation stage.

The candidate oil producer; located in Southern Area of Ghawar Field; had accumulations of hard Iron Sulfide scale inside the tubing at different depths. Acid de-scaling operation using bullheading technique utilizing 20% HCL went vain to restore well accessibility and productivity. Hence, the underbalanced coiled tubing de-scaling operation was successfully executed for the first time ever in an oil well in Saudi Arabia. The operation consisted of two CT runs executed in underbalanced conditions, where the first CT run was with milling tool and second CT run was with jetting tool. It is worth to mention that the well is equipped with two different tubing sizes (6,500′ of 4 ½″ & 300′ of 3 ½″ TBG). This variation on the tubing size resulted in operation optimization as will be illustrated on the paper.

This paper will illustrate the operation in terms of planning, risk assessment, execution, results and well performance prior and after restoring well accessibility and productivity. Moreover, the paper will highlight the optimization done during the field operation execution after obtaining extra information from the first run using milling tool.

This operation has resulted in cost saving of more than $1 MM, 30% production gain and restoration of the well full accessibility.
Overcoming Challenges, Improving Understanding, and Optimizing Liner Deployment in Long Laterals
Authors: Mathisen Kim Daniel , Sørheim Tore , Koløy Tom Rune , Decker Neil
Published: September 2016

An operator in the North Sea planned an 11-well field development which included installation of long 4-½ in. completion liners in the horizontal reservoir sections of each well. Successful completion liner deployment was identified as a major project risk based on liner deployment challenges experienced in earlier development campaigns in the field. The new drilling campaign had plans to include the longest length laterals drilled and completed in the field to date. Additional challenges included complicated geology, widely varying pore pressure profiles over the length of the laterals, and open hole stability/enlargement concerns. An incomplete understanding of the mechanisms at play in prior drilling campaigns further increased risks of not being able to achieve the planned total depth with the completion liner.

To minimize overall risk, the operator planned to use a managed pressure drilling (MPD) technique to maintain conditions as ‘near balanced’ as possible during both the reservoir drilling and completion phases of the operation. It was hypothesized that MPD would enable the successful drilling of challenging pore pressure profiles and minimize openhole stability issues. This would, in turn, improve the likelihood of successful completion liner deployment. Despite the expected positive impact of MPD techniques, a strong understanding of the downhole dynamics during deployment of the lower completion liner was needed.

To address this challenge, the operator installed a newly developed workstring dynamics logging tool directly above the liner hanger running tools. This tool continuously recorded axial loads, torque, temperature, and pressure data during the lower completion liner deployment operations. The data provided by the tool helped facilitate continuous operational and design improvements by establishing best practices and troubleshooting unexpected results/issues. The data also helped the team understand root causes and develop appropriate mitigations, significantly reducing downtime. These improvements allowed the operator to overcome known challenges from previous campaigns to achieve a robust deployment strategy and add significant project value.
Pricing Unquoted Crudes on Net-Back Basis: Where Are the High Value Markets?
Authors: Gbakon Kaase
Published: September 2016

The objective of this paper is to ascertain the value of a given crude oil stream of known quality in the different refining centres (markets) across the world. The markets have been characterized along the dimensions of regional refinery complexity, price level of regional bench marker crude, regional products pricing and freight to the markets from the crude stream source. This paper posits that a given crude stream can be valued differently in the different refining centres around the world depending on the factors outlined above.

Four refining centres namely – Asia-Pacific, USGC, NW Europe, and Middle East – are delineated across the world. Models to predict the yields of Gasoline, Mid-distillates and Fuel Oil are developed for the different refining hubs. The product yields from the refineries are estimated as a function of refineries' feedstock crude API, sulphur content, and refinery complexity. Furthermore, using the Net back Pricing Methodology, this paper compares the Gross Product Worth (GPW) of a given crude stream with the GPW of the benchmark crude in a given refining centre accounting for freight differences. This procedure results in the value differential (ΔP) between the given crude and the regional bench mark crude, which is then added to the price assessment of the benchmark crude to give the Free On Board (FOB) value of the crude stream.

The analysis shows that crude streams can be valued differently in the different refining centres around the world. The results show broadly, that lower API crudes can be valued higher in refineries with higher complexity than in lower complexity refineries. Whereas, the higher API crudes are valued lower in higher complexity refineries than in lower complexity refineries.

This paper illuminates a basis for performing "alternative-crude" analysis and builds a strong value proposition for unquoted crudes in the global crude oil market around regional refinery capability. Furthermore, the paper points the way in knowledgably negotiating freight contracts to target markets for crude streams matched to those markets. This is done such that Freight costs volatility do not erode the GPW advantage that can be gained by a given crude over the regional bench mark crude.
End of Tubing EOT Placement Effects on the Two-Phase Flow Behavior in Horizontal Wells: Experimental Study
Authors: Dinata Randy , Sarica Cem , Pereyra Eduardo
Published: September 2016

An experimental study investigating the effects of end of tubing (EOT) on the two-phase gas-liquid flow behavior in horizontal wells was performed. The experimental data were used to develop methodologies to determine the optimum EOT location for the observed flow types: stable and cyclic flows. Total pressure drop, liquid inventory and the two-phase flow hydrodynamic behavior were analyzed to determine the optimum EOT location criteria. Tubingless completion and four packerless EOT locations were tested using a transparent laboratory-scale flow loop facility resembling two horizontal well configurations: toe-up and toe-down with 1-in. tubing and 2-in. casing. Water and compressed air were used as test fluids with various constant flow rates under low pressure. Minimum total pressure drop in the well was used to determine the optimum EOT location for stable flow. Various total pressure drop vs. EOT location relationships were observed under different operating conditions. Under low gas flowrates, installing tubing may promote severe slugging (SS) for a toe-up system. EOT located at kick-off point may be preferred as it showed the least test number of points with SS behavior. In addition, this location generated the lowest liquid holdup in the tubing and backpressure to the lateral section in most cases. The observations to explain these findings and the comparison of the tested EOT locations in handling SS were discussed.
Determination of Preferential Flow Direction in a Low Permeability Carbonate Reservoir Through Real-Time Data and Rate Transient Analysis RTA
Authors: Alcantara R. , Vazquez J. L. , Briones M.
Published: September 2016

The determination of the preferential flow direction in a reservoir becomes a very important subject for the development of an oilfield, especially for the selection of the optimum exploitation strategy taking into account that porous media is a very complex environment in which representing the flow behavior of fluids becomes a tough task, mainly in carbonates where the distribution of fractures, lithology changes and diagenesis play a major role in this topic.

Naturally Fractured Reservoirs (NFR) represent a great technical challenge for the petroleum industry because they behave as a heterogeneous medium with a strong influence of diagenesis, a term that encompasses fractures, dissolution, compaction, dolomitization, cementation and recrystallization to conform a reservoir with totally different distribution of properties. The dynamic data must be evaluated in order to match with the static model achieving a good reservoir characterization.

In this paper we present a way to determine the preferential flow direction by the monitoring of the field through permanent real-time downhole gauges that allowed the identification of the interference between wells in a deep naturally fractured reservoir that originally did not show any degree of communication. Suddenly, after some producing time, the field demonstrated a great level of interference among wells and as a consequence, the determination of the preferential flow direction was possible through Pressure Transient Analysis (PTA) and Rate Transient Analysis (RTA). Emphasizing the Palacio-Blasingame1 type curves (PBTC), in which we compare the results obtained using this analysis with its standard form and the one achieved with Material Balance Time (MBT). Additionally, Fetkovich2 decline type curves were also used in the rate analysis.

Finally, a comparison of the geological model with the dynamic data was also applied to further enhance the quality of the data. The results showed conclusive preferential flow direction with the wells tested.
Low-Velocity Non-Linear Numerical Simulation in Tight Sandstone Oil Reservoirs
Authors: Tian Xiaofeng , Cao Renyi , Tian Ji , Cheng Linsong , Zhang Miaoyi
Published: September 2016

Micro and nano throats are widely distributed in tight sandstone oil reservoirs and non-linear flow characteristics are obvious. However, no existing non-linear mathematical models and numerical simulations account for the effect of throat radius heterogeneity and fluid on non-linear flow characteristics. Additionally, they aslso do not account for the mutation of relative permeability curve resulted from non-linear flow characteristics. Therefore, in this paper, based on the method to characterize the non-linear flow characteristics and to calculate the relative permeability with non-linear flow characteristics, non-linear mathematical model is built. Then the numerical simulation module is developed. It is found that because of the effect of non-linear flow characteristics and quasi threshold pressure gradient, the early oil production of conventional model is largest and that of quasi threshold pressure gradient (QTPG) model and non-linear model are the same. Additionaly, QTPG model overestimates the threshold pressure gradient. Therefore, the sweep and cumulative oil production of conventional model is larger than that of non-linear model, larger than that of QTPG model. Becasuse the middle of the production well and injection well has the minimal pressure gradient, it has the minimal effective permeability. Accounting for the effect of non-linear flow characteristics and permeability stress sensitivity on relative permeability, the sweep area of injected water is small. Although the permeability is the same, the non-linear flow characteristics and permeability stress sensitivity are more obvious when throat distribution is narrower. As a result, the effective permeability is lower and sweep area become smaller. Therefore, oil rate and cumulative oil production is lower.
Performance Comparison of Novel Surfactant-scCO2 Systems for Oil Recovery in High Salinity Carbonate Reservoirs
Authors: Jangda Zaid , Sultan Abdullah
Published: September 2016

Recent work on CO2 Enhanced Oil Recovery (CO 2EOR) has focused on the design of fluid systems that have the ability to overcome the deficiencies typically associated with CO2 injection. However, applicability remains a challenge due to the instability of the developed fluid systems at reservoir conditions. The objective of this work was to evaluate and compare novel surfactant-CO2 systems that improve oil recovery.

For this purpose, multiple core-flooding experiments were conducted at high temperature (90°C) and high pressure (1800 psi) and in high saline conditions (TDS>200,000 ppm) to mimic actual reservoir conditions. Three novel surfactant solutions (an amphoteric fluoro-surfactant, a hydrocarbon surfactant and a visco-elastic surfactant) were co-injected with sc-CO2 in foot long carbonate cores to compare their stability and effectiveness in incremental oil recovery. Interfacial Tension (IFT) experiments were also performed with the most performant surfactant at the same conditions and surfactant concentration to further highlight its contribution in increasing oil recovery.

Results from this comparative core-flooding study clearly demonstrate that when combined with sc-CO2, the fluoro-surfactant provided a much higher oil recovery than the hydrocarbon or the visco-elastic surfactant (6-9% increase). The pressure difference between the outlet and inlet of the core (ΔP) during flooding was also much higher for the fluoro-surfactant system indicating possible foam generation. The use of surfactants with CO2 also delayed the breakthrough of CO2 which allowed for longer contact between the oil and CO2. IFT results also showed a significant drop in interfacial tension between reservoir oil and the injected fluid after adding the fluoro-surfactant.

This work provides a novel option for surfactant-scCO2 flooding that overcomes the shortcomings of CO2 gas injection leading to an increase in total oil recovery. The fluoro-surfactant performs exceptionally well even at the very low concentration used in this study which also reduces the overall cost of the design.