bluuebunny/crossref_metadata_2025 huggingface dataset:
Transition to Adulthood: Delays and Unmet Needs Among Adolescents and Young Adults With Asthma
Authors: Duplantier John E.
Published: October 2008

Scal P, Davern M, Ireland M, Park K. J Pediatr. 2008;152(4):471–475

PURPOSE OF THE STUDY. To examine the effect of the transition to adulthood on financial and nonfinancial barriers to care in youths with asthma.

STUDY POPULATION. Studied were adolescents and young adults with asthma. Public-use data from the National Health Interview Survey conducted by the National Center for Health Statistics were analyzed. Data from the years 2000–2005 were pooled to provide a sample of 26 597 adolescents (12–17 years) and 19 998 young adults (18–124 years).

METHODS. Subjects were classified as having delayed care because of financial barriers when during the previous 12 months they had delayed seeking medical care because of concerns about affordability. Similarly, an unmet need because of a financial barrier was identified when during the previous 12 months the respondents indicated that they had failed to receive needed medical care or prescription medication because they could not afford it.

RESULTS. More young adults than adolescents encountered financial barriers that resulted in delays (18.6% vs 8%; P < .05) and unmet needs (26.6% vs 11.4%; P < .05). Delays caused by nonfinancial barriers were similar (17.3% vs 14.9%; P was not significant).

CONCLUSIONS. Delays and unmet needs caused by financial reasons were significantly higher for young adults with asthma compared with adolescents with asthma.

REVIEWER COMMENTS. It is crucial for everyone who treats children with asthma to recognize the potential vulnerability of these patients as they transition to adulthood. Appropriate counseling and written materials regarding health insurance might be helpful, as might providing lists of resources for free or reduced-cost care that are available in the local community.
Effect of Different Antiasthmatic Treatments on Exercise-Induced Bronchoconstriction in Children With Asthma
Authors: Kennedy Joshua L. , Jones Stacie M.
Published: October 2008

Stelmach I, Grzelewski T, Majak P, Jerzynska J, Stelmach W, Kuna P. J Allergy Clin Immunol. 2008;121(2):383–389

PURPOSE OF THE STUDY. To compare the effectiveness of different patterns of antiasthmatic treatments to protect children from exercise-induced bronchospasm (EIB).

STUDY POPULATION. This was a randomized, double-blind, placebo-controlled study of 100 children aged 6 to 18 years with atopic asthma sensitive only to house dust mites and EIB. Subjects must have had a resting forced expiratory volume in 1 second (FEV1) of ≥70% predicted and at least a 20% drop in FEV1 after exercise to qualify for the study.

METHODS. Participants were randomly assigned to a 4-week double-blind, placebo-controlled trial to receive 1 of the following treatments: (1) budesonide 100 μg + formoterol 4.5 μg twice daily; (2) budesonide 100 μg twice daily + montelukast 5 or 10 mg at bedtime; (3) montelukast 5 or 10 mg at bedtime; (4) budesonide 100 μg twice daily; or (5) placebo alone. All study arms had matching placebo medications from which active drugs were omitted (eg, group 1 had placebo tablets in place of montelukast, etc). At randomization and after 4 weeks on the study medication(s), a treadmill exercise test was performed to evaluate the effectiveness of treatment.

RESULTS. Ninety-one subjects with a median age of 11.3 to 12.2 among the groups completed the study. Preexercise FEV1 and EIB, as represented by the area under the curve of time-response curve and by maximum percentage decrease in FEV1 after exercise, did not differ at baseline between the groups. EIB was diminished with all treatments when compared with placebo. The effect of treatment with budesonide plus montelukast and with montelukast alone were greater than budesonide alone or budesonide plus formoterol (P < .001). The budesonide-plus-formoterol group was also better than budesonide alone, but these results did not reach significance (P = .59).

CONCLUSIONS. Budesonide plus montelukast or montelukast alone were the most effective treatments for EIB in children.

REVIEWER COMMENTS. This was the first study in asthmatic children that evaluated both monotherapy and combination therapy for the reduction of EIB. This study highlights the importance of controller therapy in childhood asthma and the effects on EIB between therapeutic options recommended for childhood asthma. In particular, consideration for the use of montelukast as monotherapy or in combination therapy with inhaled corticosteroids is indicated for EIB in children with similar asthmatic phenotypes.
First molecular identification of ‘ Candidatus Mycoplasma haemominutum’ from a cat with fatal haemolytic anaemia in Hungary
Authors: Hornok Sándor , Meli Marina , Gönczi Enikő , Ignits Éva , Willi Barbara , Lutz Hans , Hofmann-Lehmann Regina
Published: October 2008

Although haemobartonellosis was previously reported in Hungary, until now the diagnosis (based on morphological identification in blood smears) has only been suggestive of the occurrence of the large species, recently reclassified asMycoplasma haemofelis. However, in July 2007 a cat was presented at a small animal clinic with severe haemolytic anaemia, icterus and haemoglobinuria. While biochemical parameters were within the reference range, the cat had leukocytosis and rapidly decreasing haematocrit values, and eventually died 7 days after the sudden onset of aggravating clinical signs. From blood samples of the cat ‘CandidatusMycoplasma haemominutum’ was identified by molecular methods, according to its 100% 16S rRNA gene sequence homology with two Swiss isolates and one isolate from the UK. The rapid termination of the disease and the high pathogenicity of the causative agent observed in this case are unusual, taking into account that PCR results were negative for immunosuppressive viruses. This is the first record of this feline haemoplasma species in Hungary.
Field efficacy of combination vaccines against bovine respiratory pathogens in calves
Authors: Makoschey Birgit , Muñoz Bielsa Juan , Oliviero Loïc , Roy Olivier , Pillet Florence , Dufe Divine , Valla Giorgio , Cavirani Sandro
Published: October 2008

The efficacy of an inactivated bovine respiratory syncytial virus (BRSV) — bovine parainfluenza type 3 (PI3) —Mannheimia haemolytica(Mh) combination vaccine was examined in two field studies. Calves were vaccinated (i) with the inactivated vaccine, (ii) a modified live/killed viral combination vaccine, or (iii) left unvaccinated. The efficacy of the vaccines was judged by the (i) number of treated animals, (ii) number of individual antibiotic treatments per calf and (iii) mortality rates. After vaccination with the inactivated vaccine, the number of calves requiring antibiotic treatment was significantly lower than in the unvaccinated group (odds ratios: 0.26 first study and 0.53 second study), but differences between vaccination with live/killed combination vaccines and controls were not significant (odds ratios: 0.56 and 0.90, respectively). In both studies, a number of unvaccinated controls died due to respiratory disease (4.6% first and 6.7% second study). By contrast, none of the animals vaccinated with the inactivated vaccine died in the first study and only 3.3% in the second study. The mortality rates for the groups vaccinated with the live vaccine (1.3% and 7.8%) were similar to the unvaccinated controls. In summary, these data demonstrate the efficacy of the inactivated vaccine under field conditions.
Size effects in LiF micron-scale single crystals of low dislocation density
Authors: Nadgorny Edward M. , Dimiduk Dennis M. , Uchic Michael D.
Published: October 2008

This study examines the size-dependent deformation response of pure LiF single crystals using microcompression testing. Microcrystals with an 〈001〉 orientation and sample diameter D ranging from 1 to 20 μm were fabricated by focused ion beam (FIB)-milling from bulk crystals having a low initial dislocation density. Both as-grown and γ-irradiated crystals were examined to characterize the effect of an increased point defect density on the size-affected plastic flow response. Similar to previously studied face-centered cubic (FCC)-derivative metals, both types of LiF microcrystals exhibit typical size-dependent plastic flow behavior: a dramatic size-dependent and statistically varying flow stress, atypically high strain hardening rates at small plastic strains, and fast intermittent strain bursts. The size-dependent strengthening obeys a power law, σ ∼ D−m, where m ≈ 0.8, and this rapid hardening results in engineering flow stresses of 650 MPa in 1-μm samples. The findings are evaluated against possible dislocation mechanisms that could be responsible for the observed size effects.
Quantitative chemical analysis of fluorite-to-perovskite transformations in (Pb,La)(Zr,Ti)O3 PLZT thin films
Authors: Parish Chad M. , Brennecka Geoff L. , Tuttle Bruce A. , Brewer Luke N.
Published: October 2008

Lead loss during processing of solution-derived Pb(Zr,Ti)O3 (PZT)-based thin-films can result in the formation of a Pb-deficient, nonferroelectric fluorite phase that is detrimental to dielectric properties. It has recently been shown that this nonferroelectric fluorite phase can be converted to the desired perovskite phase by postcrystallization treatment. Here, quantitative standard-based energy-dispersive x-ray spectrometry (EDS) in a scanning transmission electron microscope (STEM) is used to study cation distribution before and after this fluorite-to-perovskite transformation. Single-phase perovskite PbZr0.53Ti0.47O3 (PZT 53/47) and Pb0.88La0.12Zr0.68Ti0.29O3 (PLZT 12/70/30) specimens that underwent this treatment were found to be chemically indistinguishable from the perovskite present in the multiphase specimens prior to the fluorite-to-perovskite transformation. Significant Zr–Ti segregation is found in PLZT 12/70/30, but not in PZT 53/47. Slight La-segregation was seen in rapidly crystallized PLZT, but not in more slowly crystallized PLZT.
Formation of LuFe2O4 phase from an undercooled LuFeO3 melt in reduced oxygen partial pressure
Authors: Kumar M.S. Vijaya , Kuribayashi Kazuhiko , Kitazono Koichi
Published: October 2008

The formation of metastable phases from an undercooled LuFeO3 melt was investigated under reduced Po2 since the iron ion has the tendency to change its valence state from Fe3+ to Fe2+ in an ambient atmosphere with low Po2. The nucleation and the post-recalescence temperatures of the phases were decreased with decreasing process Po2. Phase equilibrium was established in the Lu–Fe–O system at 1473 K by varying the oxygen partial pressure from 105 to 10−1 Pa. A possible ternary metastable phase diagram depending on the oxygen composition in the bulk sample was also constructed. The formation of the LuFe2O4 phase where the Fe3+ and Fe2+ ratio is 1:1 clearly indicated that the formation of metastable phases is related to the presence of Fe2+ ions. Thermogravimetric analysis revealed that the increase in sample mass with decreasing process Po2, down to 10−1 Pa, is relatively dependent on the amount of Fe2+ ions.
Synthesis and characterization of Cr–B–N coatings deposited by reactive arc evaporation
Authors: Polychronopoulou K. , Neidhardt J. , Rebholz C. , Baker M.A. , O’Sullivan M. , Reiter A.E. , Gunnaes A.E. , Giannakopoulos K. , Mitterer C.
Published: October 2008

Nanocomposite Cr–B–N coatings were deposited from CrB0.2 compound targets by reactive arc evaporation using an Ar/N2 discharge at 500 °C and −20 V substrate bias. Elastic recoil detection (ERDA), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED) were used to study the effect of the N2 partial pressure on composition and microstructure of the coatings. Cross-sectional scanning electron microscopy (SEM) showed that the coating morphology changes from a glassy to a columnar structure with increasing N2 partial pressure, which coincides with the transition from an amorphous to a crystalline growth mode. The saturation of N content in the coating confirms the formation of a thermodynamically stable CrN–BN dual-phase structure at higher N2 fractions, exhibiting a maximum in hardness of approximately 29 GPa.
A Novel Method of Dynamic Culture Surface Expansion Improves Mesenchymal Stem Cell Proliferation and Phenotype
Authors: Majd Hicham , Wipff Pierre-Jean , Buscemi Lara , Bueno Manuel , Vonwil Daniel , Quinn Thomas M. , Hinz Boris
Published: October 2008

Repeated passaging in conventional cell culture reduces pluripotency and proliferation capacity of human mesenchymal stem cells (MSC). We introduce an innovative cell culture method whereby the culture surface is dynamically enlarged during cell proliferation. This approach maintains constantly high cell density while preventing contact inhibition of growth. A highly elastic culture surface was enlarged in steps of 5% over the course of a 20-day culture period to 800% of the initial surface area. Nine weeks of dynamic expansion culture produced 10-fold more MSC compared with conventional culture, with one-third the number of trypsin passages. After 9 weeks, MSC continued to proliferate under dynamic expansion but ceased to grow in conventional culture. Dynamic expansion culture fully retained the multipotent character of MSC, which could be induced to differentiate into adipogenic, chondrogenic, osteogenic, and myogenic lineages. Development of an undesired fibrogenic myofibroblast phenotype was suppressed. Hence, our novel method can rapidly provide the high number of autologous, multipotent, and nonfibrogenic MSC needed for successful regenerative medicine.
Chromatin Modifications in Hematopoietic Multipotent and Committed Progenitors Are Independent of Gene Subnuclear Positioning Relative to Repressive Compartments
Authors: Guillemin Claire , Maleszewska Marta , Guais Adeline , Maës Jérôme , Rouyez Marie-Christine , Yacia Azzedine , Fichelson Serge , Goodhardt Michele , Francastel Claire
Published: October 2008

To further clarify the contribution of nuclear architecture in the regulation of gene expression patterns during differentiation of human multipotent cells, we analyzed expression status, histone modifications, and subnuclear positioning relative to repressive compartments, of hematopoietic loci in multipotent and lineage-committed primary human hematopoietic progenitors. We report here that positioning of lineage-affiliated loci relative to pericentromeric heterochromatin compartments (PCH) is identical in multipotent cells from various origins and is unchanged between multipotent and lineage-committed hematopoietic progenitors. However, during differentiation of multipotent hematopoietic progenitors, changes in gene expression and histone modifications at these loci occur in committed progenitors, prior to changes in gene positioning relative to pericentromeric heterochromatin compartments, detected at later stages in precursor and mature cells. Therefore, during normal human hematopoietic differentiation, changes in gene subnuclear location relative to pericentromeric heterochromatin appear to be dictated by whether the gene will be permanently silenced or activated, rather than being predictive of commitment toward a given lineage.
Generation of T Lineage Cells from Human Embryonic Stem Cells in a Feeder Free System
Authors: Galić Zoran , Kitchen Scott G. , Subramanian Aparna , Bristol Greg , Marsden Matthew D. , Balamurugan Arumugam , Kacena Amelia , Yang Otto , Zack Jerome A.
Published: October 2008

Human embryonic stem cells (hESC) have the potential to revolutionize certain medical treatments, including T-cell-based therapies. However, optimal approaches to develop T cells from hESC are lacking. In this report, we show that T-cell progenitors can be derived from hESC cultured as embryoid bodies (EBs). These EB-derived T-cell progenitors give rise to phenotypically and functionally normal cells of the T lineage when transferred into human thymic tissue implanted in immunocompromised mice, suggesting that introduction of these progenitors into patients may also yield functional T cells. Moreover, hematopoietic progenitors demonstrating T-cell potential appeared to be CD45+/CD34+, resembling those found in normal bone marrow. In contrast to T cells developed from hESC cocultured on murine stromal cells, the EB-derived T cells also expressed normal levels of CD45. Importantly, the EB system eliminates the previous need for murine cocultures, a key impediment to developing a protocol for T-cell progenitor derivation suitable for clinical use. Furthermore, following lentiviral-mediated introduction of a vector expressing enhanced green fluorescent protein into hESC, stable transgene expression was maintained throughout differentiation, suggesting a potential for gene therapy approaches aimed at the augmentation of T-cell function or treatment of T-cell disorders.
Application and Evaluation of Tubing-Conveyed Perforating System Combined with Sucker Rod Pump Installation
Authors: Ghareeb Mohamed , Shedid Shedid A. , Amani Mahmood
Published: October 2008

Underbalanced tubing conveyed perofration (TCP) attained higher production and assured safety when applied with sucker-rod pump installation in wells in three different Egyptian oil fields. The TCP allowed more efficient operation because it does not require killing the well after perforation to run the downhole pump and sucker rod. The overbalanced perforation eliminates the risks of damaging the producing formation beyond the perforations.

The compared performance of wells using underbalanced TCP with that of other wells using tubing gun technique, casing gun technique eveals that the underbalanced TCP prevailed successful in all cases.
The Integrated Use of New Technology in the Development of the Sakhalin II Project
Authors: Gunningham Mike , Varley Chris
Published: October 2008

The Sakhalin II Project, the world’s largest E&P project, is currently developing 2 oil and gas fields, offshore Sakhalin Island off the east coast of mainland Russia. This is a challenging area for exploration and development, with 4.5 Billion BOE (675 Million tonnes oil equivalent) of oil and gas in place. This paper will outline how new technologies have assessed and realized the Project’s potential.

Integrated Reservoir Modeling, utilizing modern seismic processing and interpretation, to evaluate short, medium- and long-term subsurface uncertainties, and to support development planning and reservoir management. The results have been combined into a fully integrated production system model from each reservoir to the LNG plant and Oil Export Terminal.

The Lunskoye field, which is being developed with the highest capacity gas wells in Russia, has used the latest sand failure prediction software, which can quantify sand production, so that gas production is optimized, while minimizing sand production. Production performance is enhanced using the latest perforating optimization software.

In the Piltun-Astokh field, Smart Water Injectors are used to allocate water into multiple layers to optimize reservoir recovery. In addition, extended reach wells are tapping into undrained areas of the field, to recover additional reserves, reducing the environmental footprint. The field will also be developed with the latest in Smart Field technology for well and reservoir management, using tools such as Fieldware. Longer term, 4-D seismic, using whale friendly seismic, will be implemented to identify infill drilling locations.

For the future, in this sub-Arctic environment, the opportunities include acquiring seismic under ice, Arctic (ice resistant) jack-up drilling rigs for year-round drilling and developing low-cost facilities, which can withstand the ice or even be installed subsea, under ice.
Creative Production Enhancement Applications of Relative Permeability Modifiers in Mature Fields
Authors: Kalfayan Leonard , Qu Qi , Stolyarov Sergey
Published: October 2008

There is increasing emphasis on enhancing production and extending economic life of mature fields, especially including waterflood operations, globally. With that, it stands to reason that greater focus should be placed on controlling production of unwanted water relative to oil and gas production, as well as on improving the utilization of the large volumes of water to optimize waterflood sweep efficiency.

Mechanical and chemical treatment methods for shutting off or at least controlling, unwanted water production have existed for many years. Technologies and methods continue to evolve, albeit slowly. The same is true for injection well treatments for profile modification and improved oil reservoir sweep efficiency purposes. In the family of chemical treatments confined to production wells for controlling water rate are the so-called relative permeability modifiers (RPMs). Despite the long-standing (and continuing) skepticism of RPMs, in general, their implementation has increased in recent years – including uses in conjunction with oil and gas well stimulation treatments. Certainly, some of the criticism of RPMs is justified as they are often misapplied beyond their realistic physical and chemical capabilities. However, the creative application of RPM chemistry in production enhancement applications and in waterflood operations should not be generally dismissed or discouraged.

This paper discusses creative uses of RPM systems with properties conducive to application in both matrix and naturally-fractured sandstones and carbonates. Such applications include using RPM systems in hydraulic fracturing, acidizing, scale removal and inhibition, salt block inhibition, and waterflood injection profile modification. Both conceptual and field-proven applications are included. Results of laboratory studies and field case examples are presented.
Solving Linear Equations in Reservoir Simulation Using Multigrid Methods
Authors: Hammersley R. P. , Ponting D. K.
Published: October 2008

The sets of linear equations which arise in large scale reservoir simulation can present problems for traditional linear solution algorithms. These scale poorly as the number of cells increases, and convergence is limited by the use of permeability distributions from geological modelling, with correlated high permeability channels, and the modelling of long horizontal wells. In addition, there is a requirement that the solver runs well on computers with many parallel processors.

The use of multi-level methods offers the possibility of good scaling with problem size. A common approach has been to use an algebraic multigrid (AMG) method. The integration of such a technique into a parallel reservoir simulation code is described, and the performance of different coarsening and interpolation algorithms compared.

AMG methods generally perform well when solving for a scalar solution to a system of elliptic equations and are not as straightforward to generalize to vector solution variables as traditional grid-based solvers. However, in fully implicit reservoir simulation a solution change in terms of both pressures and saturations or molar densities is generally required. This has lead to the use of solvers which combine an AMG step with a secondary solver step. There can be advantages in selecting nonlinear variables and equation sets to suit this technique, rather than treating the linear solver as a self-contained black box. Such methods are described and compared with traditional methods for black oil and compositional simulation.
Utilize Manage Pressure Drilling Equipment and Technique to Cement a Severely Depleted HPHT Reservoir in the North Sea
Authors: Bjørkevoll Knut Steinar , Molde Dag Ove , Fjeldberg Helge
Published: October 2008

The paper describes the successful use of an advanced comprehensive managed pressure setup to run and cement a liner that covered reservoir layers with pressures ranging from no depletion to 130 bar depletion in the Kvitebjorn field in the North Sea. The setup, which was first used for drilling the same 8.5" section, included a rotary control head, use of Cs/K formate mud, automatic choke on return flow, and an advanced online dynamic flow and temperature model for calculation of choke pressure set-point. The model was also used for pre-calculations of various scenarios to be prepared for different eventualities.

The paper describes methods and setup, planning and execution of operations, analyzes calculations vs. measured data, and discusses training and organizational aspects of conducting such a complex operation.

The managed pressure setup was motivated by several occasions of losses, partly severe, in nearby wells, and a narrow drilling window.

This is, to the authors’ knowledge, the first time running and cementing a liner has been done with an automatic choke system controlled in real time by an online dynamic flow model. Managed pressure cementing has been done earlier on the Gullfaks field in the North Sea, but then with a manually operated rig choke based on pre-calculated pressures only.

After having resolved a number of technical issues and trained thoroughly personnel for using the actual set-up, running and cementing liner could be conducted with good pressure control, and with no significant losses of drilling fluid. Later logging confirmed that the cement job was good.

Important factors to ensure high probability of success included thoroughly tested equipment and model,good knowledge of limitations of the system,comprehensive preparations, including pre-simulations and training,detailed procedures, including contingencies,good communication during operations
Wax Modeling: There is Need for Alternatives
Authors: Bagatin R. , Busto C. , Correra S. , Margarone M. , Carniani C.
Published: October 2008

Wax deposition in pipelines is a constant concern in Flow Assurance studies. When the temperature along a pipeline falls below the so-called Wax Appearance Temperature (WAT) of the oil, various problems due to wax precipitation and deposition may happen: wax can deposit on pipewalls, wax particles can increase the viscosity, and, due to plant shut-down, wax can cause the crude oil to gel. To counter-act wax problems, two approaches are possible: prevention (like e.g. insulating the pipe or adding chemicals to the oil) or removal (like e.g. pigging the line). In order to correctly design pipelines and to implement proper strategies for prevention and removal, a reliable description of the phenomenon plays a key role: without such a model, every intervention has to be oversized, dramatically increasing costs and risks.

A number of commercial codes have been developed to describe the deposition process based on a number of mechanisms (molecular diffusion, shear dispersion, Brownian diffusion, gravity settling ...) that have been proposed to elucidate the evolution of wax deposits on cold pipe walls. The comparison of these different commercial codes to each other, and with field data, represents a first result of this study. The models still present limits, many of which relate to the practical reliability of model predictions and their impact on operations:

– The relative importance of the different and/or concomitant mechanisms proposed for wax deposition modelling is still not completely clarified. – The models present a number of arbitrary or not well defined values of parameters that are often used to adjust predictions with respect to a specific experimental result. – The models have been developed using gel deposition rates observed in the laboratory flow loops and the scale-up of the deposition usually leads to an over-prediction of the wax deposition in field pipelines, due to the unavailability of a reliable upscale criterion.

In addition, the lack of detailed field data makes the qualification of the different models difficult.

Due to the failure of available models, the consolidated proposed mechanisms of wax deposition have been critically analysed. It resulted that there is need for alternatives: molecular diffusion controls wax radial transport, but this is not the only process that counts. Convective axial transport brings enough waxes to form a gel on the wall, and this gel formation is the fast process responsible of the deposit geometry.

On these bases, a new approach has been developed founded on this physical picture of the process; the comparison of its results with field data is by far better than the other ones.
Squeezing Scale Inhibitors to Protect Electric Submersible Pumps in Highly Fractured, Calcium Carbonate Scaling Reservoirs
Authors: Poynton Neil , Miller Alan , Konyukhov Dmitry , Leontieff Andre , Ganiev Ilgiz , Voloshin Alexander
Published: October 2008

Rosneft has oil fields in Western Siberia producing fluids from a number of wells via Electric Submersible Pumps (ESP's). While production rates are increased using ESP's, run time can be compromised by the formation of scale within the inner workings of the pump. The deposition of scale can be detected by the pumps requiring increasing amounts of current to maintain the flow rates. Eventually the pumps fail (either mechanically or electrically) and have to be replaced. Typically examination of these pumps indicated the main failure mechanism to be the deposition of Calcium Carbonate scale within the pump. The actual run times achieved tend to be dependant on the severity of the scaling produced water, but were typically in the order of weeks. However in some extreme cases, pump failures had occurred in a matter of days from replacement and start up.

It was proposed that one treatment strategy to increase the pump run time by inhibiting scale formation was via a Scale Inhibitor Squeeze application treatment. The Squeeze process and inhibitor application is very well understood, but to get successful squeeze treatment you need to perform adequate laboratory selection tests, including inhibition efficiency testing and core flood evaluations. This data, together with the Heriot Watt University Squeeze VI modeling can get an approximation to the potential squeeze life.

This paper presents the testwork performed to identify and develop successful Scale Inhibitor Squeeze Chemistries suitable for application in Western Siberia. It details the laboratory testing, the coreflood evaluation and Squeeze VI modeling. The Squeeze application and performance of the first well squeezed is reviewed together with a summary of the current status of the wells squeezed. An economic evaluation of the squeeze is also performed together with a summary of all the wells treated which demonstrates that the squeeze application provided a very cost effective method of scale control to maximize pump run time and increase the net well value.
Model for Transient Temperature and Pressure Behavior in Commingled Vertical Wells
Authors: Sui W. , Zhu D. , Hill A. D. , Ehlig-Economides C. A.
Published: October 2008

Multilayer transient testing is designed for determining individual layer properties (permeability and skin) for multiple layers commingled in a well. Traditional multilayer transient testing requires a combination of rate profiles from production log and transient rate and pressure measurements acquired at multiple surface rates. This method can be time consuming and may involve significant errors depending on the accuracy of the transient flow rate measurements. Today, many wells are equipped with downhole sensors that provide distributed or multipoint temperature measurements along the wellbore. Using these data to determine formation properties can minimize time and disturbances in well production. This paper presents a forward model to investigate the possibility of evaluating formation properties from transient temperature and pressure measurements. The model couples wellbore and reservoir models for simulating transient temperature and pressure for single-phase flow.

The wellbore model was developed based on mass, momentum, and energy balance. The reservoir model consists of a reservoir thermal model and a pressure/flow-rate transient model. Besides heat conduction and convection, it considers viscous heating and temperature variation due to fluid and rock expansion/compression. Wellbore and reservoir models are solved numerically to predict transient temperature and pressure behavior.

Comprehensive experiments reveal the sensitivities of transient temperature to individual layer permeability and skin values in multilayer systems. The results indicate that there are two main mechanisms governing wellbore transient temperature behavior; formation heating/cooling and wellbore fluid mixing at entry points, and that permeability and skin affect transient temperature and pressure differently. Examples in the paper show that the transient temperature response can distinguish between low permeability and high skin factor as reasons for low productivity in any layer. Additionally, this work revealed that the transient temperature behavior is sensitive to the radius of the damaged zone, suggesting for the first time a mechanism to quantify the damaged radius. The observations show promise of using transient temperature and pressure to determine multilayer formation properties.
The Economics of Compressed Natural Gas Sea Transport
Authors: Marongiu-Porcu Matteo , Wang Xiuli , Economides Michael J.
Published: October 2008

Natural gas has come to the forefront of the international energy debate. The reasons include increasing demand in the United States, China and India and a changing worldwide preference in power generation because of environmental concerns. As a result, the transport of natural gas becomes important. Currently, 70 percent of gas is transported to market by pipeline and 30 percent as liquefied natural gas (LNG).

Pipelines are attractive but, offshore, their feasibility is greatly hindered by distance limits and terrain restrictions. On the other hand LNG facilities are expensive to construct and the process is complicated, costly and energy wasteful. It is applicable primarily for long distances and large volumes of gas.

Sea-going compressed natural gas (CNG) is an alternative that has been proposed in recent years but has not made substantial headway for two reasons: 1) the emphasis for investments by producers and large consumers has been primarily on LNG; 2) CNG boat designs and projects have been envisioned to eke a bite out of the LNG pie which is not necessarily a good approach.

CNG must make a niche in smaller markets and shorter distances. Here we present definitive economics by performing a specific case study for Sakhalin Island, Russia. Results delineate the landscape where this mode of transport is attractive and how it can be deployed with specific requirements of distance, market size and size distribution. Our studies show that for shorter distances (e.g., 500 km, about 300 miles) and even relatively large volumes, LNG cannot compete with CNG and at longer distances (e.g., 2,000 km, about 1,250 miles) CNG is far more attractive at small volumes, assuming that offshore pipelines are not feasible. For volumes such as 1 to 2 billion cubic meters per year (about 35 to 70 billion cubic feet per year), CNG is the only feasible solution to bring this energy source to many markets. These findings suggest that many parts of the world (such as the entire Mediterranean basin, the Scandinavian peninsula, Sakhalin Island, South-East Asia and the Caribbean) would be better served by CNG even if LNG projects have already been approved and under construction.

We also performed a sensitivity study on gas price (both at the source and at the market) impacts on the value of both CNG and LNG projects and determine the breakeven points under a given gas demand of e.g., 1.5 Bcm/yr (about 50 Bcf/yr) and a distance of 1,500 km (about 900 miles). For example if the source price is $6/MMBtu then the breakeven price for CNG is $10.05 whereas for LNG it will have to be $14.24, a 40% increase.
Well-Test Interpretation with Behind-the-Casing Crossflows
Authors: Kremenetskiy M. I. , Kokurina V. V
Published: October 2008

This study considers the potential use of well-testing for investigating cross-flows in production wells.

Using a numerical model, the authors detected pressure behavior patterns which may become informative characteristics for diagnosing a cross-flow. To increase diagnostic reliability, the optimization of measurement technologies and interpretation methods to manage pressure behavior pattern characteristics are substantiated. These testing techniques make it possible to distinguish behind-the-casing fluid movement where background interference is present.

One of the most interesting areas of application of the results obtained in this study is monitoring unsteady fracture creation in injection wells. Such fractures occur when the injection pressure exceeds reservoir fracturing pressure, and they break down shale layers between formations. When pressure is reduced, the fractures close up, and cross-flow stops. That is why the derivative behavior during the injection cycle significantly differs from that of the static state.

Numerous examples illustrate that well testing is considerably more successful when combined with downhole logging.
A Milestone for Smart MRC Wells in Saudi Arabia
Authors: Al-Umran Mohammed I. , Al-Shenqiti Mohammad S. , Zhou Shaohua , Al-Nasif Mohammad A.
Published: October 2008

Smart completions in maximum reservoir contact (MRC) wells have played a critical role in advanced reservoir management and production optimization in Saudi Aramco. Smart MRC wells are mostly completed along the motherbore in cased holes, and occasionally in open holes. The main smart completion equipment consists of hydraulically-controlled interval control valves (ICVs), isolation packers with feed-through control lines, and permanent downhole monitoring systems (PDHMS).

Due to the complexity of smart MRC well drilling and completion, it sometimes becomes necessary to have the option to retrieve the completion equipment. Examples of these situations include downhole equipment failure during the completion process, or less than optimal or poor wellbore placement. Previous field experiences show that it can be difficult – or at least challenging – to de-complete a smart MRC well.

This paper will present a technical milestone achieved in a workover operation in November 2007. Recently, Saudi Aramco decided to workover a smart MRC well first completed in July 2005, due to poor lateral placement. After the de-completion, the plan was to sidetrack the well to regain oil production. This paper will also discuss the planning and operational steps that led to a successful three-day rig time involved with a coiled tubing (CT) operation to shift sleeves and unset packers. This resulted in the first time that smart equipment had been completely retrieved without a problem. That successful de-completion paves the way for further workover requirements of smart MRC wells, if needed. This paper will also summarize key equipment requirements and lessons learned in order to achieve successful de-completion of smart MRC wells.
Application of Brown-Field Experimental Design Techniques to a Super Giant Carbonate Reservoir
Authors: Billiter Travis C. , Dagistanova Kymbat , King Greg R.
Published: October 2008

Brown-field experimental design techniques were applied to the Tengiz super-giant carbonate reservoir. This brown-field study combined experimental design, reservoir simulation, and available historical pressure and production data to develop proxies to predict the history match quality and oil recovery of equally probable reservoir realizations. The authors used experimental design techniques similar to those documented in Landa et. al.1 and King et al.2; however, the effort documented in this paper incorporated a much larger brown-field component and highly non-linear response surfaces required many more runs (control points) to generate reliable proxies.

The initial simulations runs included a folded Plackett-Burman design with a centerpoint run and sensitivity analysis runs which varied the input parameters that were known to affect the history match. The results from these runs were analyzed using regression analysis and ANOVA techniques to determine the most significant factors and to understand the complexity of the response surfaces. With this knowledge, D-optimal runs were designed and run to better understand the effect of the interaction of the significant factors on the response surfaces. Additional sensitivity analysis runs were also made to further define the effect of the two most important factors on the response surfaces: OOIP and reservoir transmissibility. With a total of 107 unique runs, the authors were able to develop five proxies to assess history match quality and one proxy to predict oil recovery.

With the developed proxies, the authors used Monte Carlo techniques to generate equally probable reservoir/development scenarios. By using the history match quality proxies the authors were able to filter out combinations of subsurface parameters that caused unacceptable deterioration in the history match. The use of the five unique filters allowed the authors to significantly reduce uncertainty relative to the unfiltered simulation results. The results from this work were supported by material balance studies.
Well Productivity and Oil Recovery Enhancement in East and West Siberian Fields as a Result of Inflow Control Technology and Application
Authors: Kudryashov Sergey , Zaikin Igor , Kempf Konstantin , Voll Benn , Budlov Sergey , Laidlaw Duncan
Published: October 2008

A major Russian operator ROSNEFT has encountered operational risks and challenges in oil production due to the highly diverse reservoir properties of Siberian fields. The majority of the operator's east and west Siberian fields include heterogeneous sandstones with low to high permeability, complicated geological and stratigraphic cross-sections and an active bottom water aquifer. In some areas, a gas cap is one of the drive mechanisms.

Horizontal wells tend to become more popular in both green and brown fields because of improved recovery efficiency due to increased reservoir drainage area. However, unbalanced inflow profiles along horizontal sections can result in early water/gas breakthrough which shortens well life and decreases overall profitability.

This paper will describe the application of inflow control technology in two Siberian fields, addressing early water and gas breakthrough caused by intensive water injection and a massive gas cap, as well as sand control issue. Production is optimized by ensuring uniform inflow profile along lateral sections and minimizing annular flow. The setting selection process for inflow control devices is detailed. The resulting delay of water/gas breakthrough and increased longevity in these horizontal wells lead to enhanced recovery efficiency and improved productivity.
Watercut versus Oil Displacement - Main Reasons of Different Behavior
Authors: Ivanova Irina S.
Published: October 2008

Most of oil fields are developed on waterflooding. In some regions there are many fields with strong water drive. In both cases oil production is accompanied by water production.

From economical point of view income is proportional to oil production but operating expenses are proportional to liquid production. So, excessive water production can decrease profitability of a project. In some economical software there is a dependency of watercut upon oil displacement. But in reality foregoing dependencies are drastically different from field to field. This paper is devoted to finding regularities and confirmation them by means of analytical and numerical calculations.

Several influencing parameters are considered – such as relative permeabilities, fluid viscosities, fluid densities, heterogeneity and permeability profile, permeability anisotropy, layer slope, fractures, aqufer size and activity, well distance and patterns, position of perforation intervals, pressure drawdown, maximum allowed watercut. Those factors could be divided into two global groups – geological and technological.

Ultimate fraction of mobile oil displaced (volume sweep efficiency) depends on many factors. That is why field ultimate recovery factor is always less then laboratory displacement factor. But even laboratory waterflooding experiments show wide range of watercut vs. sweep dependencies for core samples from the same field. For the same maximum watercut (e.g. 98%) we can get from 0.6 to 0.9 sweep.

The quantity of water produced per unit of produced oil depends both on geology and technology. It's impossible to change geological environment but we can chose a proper method to develop any field. Field examples and practical recommendations are presented in the paper.
Setting the Standard for Resin Coated Proppant Testing
Authors: Barmatov Evgeny , Abbott Jonathan , Golovin Alexander , Burukhin Alexander , Kalinin Sergey , Straz Evgenia , Usova Zinaida
Published: October 2008

This paper describes the performance evaluation of curable resin coated proppants currently used in Russian Oilfields. The performance of these RCPs is compared based on established API/ISO standards and standard resin coated proppant testing methods currently applied within Schlumberger. These methods investigate further fluid compatibility between fluid systems and resin, proppant pack integrity under a variety and combination of curing conditions and proppant pack integrity under well flowing conditions. In the paper we evaluate the material performance of resin coated proppants used in Russia, showcase new resin coated proppant testing methods and demonstrate the need for firm industry standards devoted to the testing of resin coated proppants.