bluuebunny/crossref_metadata_2025 huggingface dataset:
Negative Line Tension for an Ionic Liquid on a Hydrophobic Fluoroalkylsilane Coating
Authors: Furuta Tsutomu , Sakai Munetoshi , Isobe Toshihiro , Nakajima Akira
Published: October 2009

Contact angles were measured for sub-nanoliter-scale droplets of an ionic liquid on an extremely smooth and homogeneous hydrophobic fluoroalkylsilane coating. Subsequently, line tension values were calculated using a new model considering the direction of hydrostatic pressure. The sign of the line tension obtained from this system was negative. Surface hydrophobicity plays an important role in determining the line tension sign.
Empirically indistinguishable multidimensional IRT and locally dependent unidimensional item response models
Authors: Ip Edward Haksing
Published: October 2009

Multidimensionality is a core concept in the measurement and analysis of psychological data. In personality assessment, for example, constructs are mostly theoretically defined as unidimensional, yet responses collected from the real world are almost always determined by multiple factors. Significant research efforts have concentrated on the use of simulated studies to evaluate the robustness of unidimensional item response models when applied to multidimensional data with a dominant dimension. In contrast, in the present paper, I report the result from a theoretical investigation that a multidimensional item response model is empirically indistinguishable from a locally dependent unidimensional model, of which the single dimension represents the actual construct of interest. A practical implication of this result is that multidimensional response data do not automatically require the use of multidimensional models. Circumstances under which the alternative approach of locally dependent unidimensional models may be useful are discussed.
Acquiescence as a source of bias and model and person misfit: A theoretical and empirical analysis
Authors: Ferrando Pere J. , Lorenzo‐Seva Urbano
Published: October 2009

In personality and attitude measurement, the presence of acquiescent responding can have an impact on the whole process of item calibration and test scoring, and this can occur even when sensible procedures for controlling acquiescence are used. This paper considers a bidimensional (content acquiescence) factor‐analytic model to be the correct model, and assesses the effects of fitting unidimensional models to theoretically unidimensional scales when acquiescence is in fact operating. The analysis considers two types of scales: non‐balanced and fully balanced. The effects are analysed at both the calibration and the scoring stages, and are of two types: bias in the item/respondent parameter estimates and model/person misfit. The results obtained theoretically are checked and assessed by means of simulation. The results and predictions are then assessed in an empirical study based on two personality scales. The implications of the results for applied personality research are discussed.
Testing multivariate mean collinearity via latent variable modelling
Authors: Raykov Tenko , Penev Spiridon
Published: October 2009

A procedure for testing mean collinearity in multidimensional spaces is outlined, which is applicable in settings with missing data and can be used when examining group mean differences. The approach is based on non‐linear parameter restrictions and is developed within the framework of latent variable modelling. The method provides useful information about the constellation of multiple response centroids in the populations studied, and is illustrated with an example.
Disengagement in work‐role transitions
Authors: Niessen Cornelia , Binnewies Carmen , Rank Johannes
Published: October 2009

The present study examines whether disengagement from previous work‐roles positively predicts adaptation to a new work‐role (here, becoming self‐employed) by reducing negative consequences of psychological attachment to these previous roles. Disengagement involves an individual's effort to release attention from thoughts and behaviours related to the previous work‐role. A three‐wave longitudinal study investigated the relationship between psychological attachment (measured as affective commitment) to a prior work‐role, disengagement from the prior work‐role, and adaptation to a new work‐role [pursuit of learning, fit perceptions with self‐employment, task performance over time]. Participants included 131 persons who recently founded a small business. Results indicated that psychological attachment to the past work‐role was negatively related to pursuit of learning and fit with the new work‐role. Disengagement from the past work‐role was positively related to pursuit of learning in the new work‐role, and buffered the negative relationship between psychological attachment and fit as well as task performance.
Linking personality to interpersonal citizenship behaviour: The moderating effect of empathy
Authors: Taylor Shannon G. , Kluemper Donald H. , Mossholder Kevin W.
Published: October 2009

To account for generally low direct relationships between Big‐Five personality traits and interpersonal citizenship behaviour (ICB), researchers have suggested that Big‐Five traits are associated with such helping‐related behaviour in interactive rather than direct fashion. This study investigated empathy as a potential moderator of Big‐Five trait – ICB relations. Hypotheses were tested with data obtained from employees of a youth treatment facility and their supervisors. Results provided evidence that empathy interacts with three Big‐Five personality traits, suggesting traits functioning at conceptually different hierarchical levels may jointly explain specific behaviours. Empathy could play an important role in understanding connections between these Big‐Five traits and ICB.
Emotion suppression affects cardiovascular responses to initial and subsequent laboratory stressors
Authors: Quartana Phillip J. , Burns John W.
Published: October 2009

Objective.The study of anger suppression and risk for cardiovascular disease has relied predominately on inspection of correlations between trait anger‐in and cardiovascular risk factors and disease. This approach tells us little about whether inhibitory processes have anything to do with outcomes, and cannot speak to whether suppression of angerper seaffects cardiovascular parameters. Drawing on the broader emotion regulation literature, we examined the effects of experimentally induced anger and general negative emotion in the context of expressive and experiential suppression on cardiovascular responses to initial and subsequent laboratory stressors.

Design.Of all participants, 201 healthy participants were randomly assigned to one of six conditions formed by crossing emotion (anxiety, anger) and suppression (experiential, expressive, control) conditions.

Methods.Participants completed a mental arithmetic task with anxiety or anger induction under their respective suppression manipulation instructions, and subsequently were exposed to a cold pressor task. Systolic blood pressure (SBP), diastolic blood pressure, and heart rate values were obtained for each experimental epoch.

Results.More robust SBP responses to the initial stressor were evidenced for those in the expressive versus the control condition. In response to the subsequent stressor, those in the experiential suppression condition showed the most pronounced SBP responses, suggesting pronounceddelayedeffects of this type of suppression. Effects of suppression on SBP reactivity were indistinguishable across anxiety and anger conditions.

Conclusion.Effortful suppression of negative emotion has immediate and delayed consequences for stress‐induced cardiovascular reactivity. Theoretical and clinical significance of these findings are discussed.
Propensity Scores: Method for Matching on Multiple Variables in Down Syndrome Research
Authors: Blackford Jennifer Urbano
Published: October 2009

Confounding variables can affect the results from studies of children with Down syndrome and their families. Traditional methods for addressing confounders are often limited, providing control for only a few confounding variables. This study introduces propensity score matching to control for multiple confounding variables. Using Tennessee birth data as an example, newborns with Down syndrome were compared with a group of typically developing infants on birthweight. Three approaches to matching on confounders—nonmatched, covariate matched, and propensity matched—were compared using 8 potential confounders. Fewer than half of the newborns with Down syndrome were matched using covariate matching, and the matched group was differed from the unmatched newborns. Using propensity scores, 100% of newborns with Down syndrome could be matched to a group of comparison newborns, a decreased effect size was found on newborn birthweight, and group differences were not statistically significant.
Digital militainment by design: producing and playing SOCOM: U.S. Navy SEALs
Authors: Mirrlees Tanner
Published: October 2009

This article examines the nexus of global digital capitalism and US militarism in two popular war games: SOCOM I: Navy SEALs (SOCOM I) and SOCOM II: U.S. Navy SEALs (SOCOM II). SOCOM supports digital capitalism's economic interests and the US military's promotional goals
in four related contexts. In its production context, SOCOM is glocalized digital militainment that was synergistically co-produced by Sony Corporation (a media corporation, based in Tokyo, Japan), Zipper Interactive (a US game design firm based in Redmond, Washington) and US Naval Special
Warfare (an elite branch of the US Navy). In its development context, SOCOM is a hyperreal war game that was digitally designed to simulate Network Centric Warfare (NCW) and cyborg-soldiering; it serves PS2 branding functions and US Navy SEALs promotion and recruitment functions. In
its publishing/circulation context, SOCOM's marketing messages visually merge the home front and battle front and promote militarized play as hyper-masculine identity affirmation. In the context of play, SOCOM's design structures virtual cyborg-soldiering.
Writing the body: The hypertext of photography
Authors: Paakspuu Kalli
Published: October 2009

In Canada and the United States the transformative value of a photograph was quickly recognized for nation building, and this new invention soon served a purpose in public memory. Its uses expanded from surveying lands to promoting population growth, tourism, artistic expression and
to imagining virtual communities. Photography's narrative, however, offers readers a commentary on knowledge, identity and memory within an interactive space that is a dialogue between subject and photographer and a visual writing the body. A subject's presence and intentionality through this
writing the body is a significant locus for knowledge and alterity - the construction of cultural otherness. Indigenous people viewing early photographs of family members may glimpse past a genre's rhetoric and actually experience their people in a lived historical moment. This essay examines
the genre rhetoric of E.S. Curtis's photographs and Indigenous writing the body as a source of mnemonic knowledge. Photography addresses our senses and extends them while it gives form to a knowledge of being in a photographic hypertext that evokes public memory and references the personal,
social and political.
What's the story? Online news consumption in the 2005 UK election
Authors: Schifferes Steve , Lusoli Wainer , Ward Stephen
Published: October 2009

This article examines the role of online news consumption in the 2005 UK General Election. In particular, it uses public opinion survey data and log file data from the BBC News Election website to assess: (1) the growth and patterns in online news consumption; (2) the ways in which
website visitors' consume online news; (3) the potential links between online news consumption and political participation and voter turnout. The data indicates that although online news consumption is still a minority interest, it is growing rapidly but as part of a wider news diet. In terms
of the online news audience, a minority of politically interested and engaged citizens are using online sources to supplement and increase their political information. However the majority of online news surfers tend to either use it on a one-off occasion or for irregular monitoring of the
campaign.
Political authority as genuineness how to transgress new public spheres
Authors: Bang Henrik Paul , Jrgensen Signe Kjr
Published: October 2009

The article argues that the basis for identification for the politicians vis--vis the citizenry has changed and that this has had consequences for the Habermasian perception of public deliberation and legitimacy. We reconsider the concepts of identification and legitimacy and argue that they can be conceptualized by a special rhetorical figure, so-called formulations of genuineness. They help to legitimize proposals to heterogeneous audiences by means of ad hoc incorporation of different value-systems and frames of reference. We illustrate our thesis with quotations from nomination letters written by the current chairmen of the Danish Social Democratic Party and Socialist People's Party. We further elaborate on a concept of celebrity public sphere and we show how it is constituted by the media. We argue that such spheres empower lay people to enter the sphere for political action with immediate effects for society so-called good governance. By means of engaging lay-people in an ad hoc fashion we argue that participatory and deliberative ideals of democracy are met in a new fashion.
Parent- Versus Child-Reported Functional Health Status After the Fontan Procedure
Authors: Lambert Linda M. , Minich L. LuAnn , Newburger Jane W. , Lu Minmin , Pemberton Victoria L. , McGrath Ellen A. , Atz Andrew M. , Xu Mingfen , Radojewski Elizabeth , Servedio Darlene , McCrindle Brian W. ,   for the Pediatric Heart Network Investigators
Published: October 2009

OBJECTIVE: We sought to compare perceptions of functional health status between children who had undergone a Fontan procedure and their parents.

METHODS: Fontan procedure survivors 10 to 18 years of age were included in the study if the child completed the Child Health Questionnaire (CHQ) and the parent completed the parent form to assess the child's functional health status. Comparisons were made between raw domain scores for the parent- and child-completed CHQs.

RESULTS: Between March 2003 and April 2004, 1078 Fontan survivors were screened. Of the 546 eligible and consented patients, 354 were 10–18 years of age and 328 parent/child pairs completed the CHQs. Parents reported significantly lower scores (worse functioning) for their children than the children reported for themselves in the domains of physical functioning (P < .01), impact on school or activities from emotional and behavioral problems (P < .01), impact on school or activities from physical health issues (P < .01), general behavior (P < .01), mental health (P < .01), self-esteem (P < .01), and general health perceptions (P < .01). No significant differences were noted for the domains of bodily pain, family cohesiveness, or family activities. For the physical functioning domain, factors contributing to lower scores for parent versus child reports included pulmonary artery anomalies and fenestration at the time of the Fontan operation. Lower parent-reported scores also were associated with more noncardiac health problems in the child.

CONCLUSIONS: Parents' perceptions of the functional health status of their children after the Fontan procedure were worse than the children's perceptions.
Secondhand and Prenatal Tobacco Smoke Exposure
Authors: Best Dana ,   Committee on Environmental Health,   Committee on Native American Child Health,   Committee on Adolescence
Published: October 2009

This Technical Report was retired November 2017.

Secondhand tobacco smoke (SHS) exposure of children and their families causes significant morbidity and mortality. In their personal and professional roles, pediatricians have many opportunities to advocate for elimination of SHS exposure of children, to counsel tobacco users to quit, and to counsel children never to start. This report discusses the harms of tobacco use and SHS exposure, the extent and costs of tobacco use and SHS exposure, and the evidence that supports counseling and other clinical interventions in the cycle of tobacco use. Recommendations for future research, policy, and clinical practice change are discussed. To improve understanding and provide support for these activities, the harms of SHS exposure are discussed, effective ways to eliminate or reduce SHS exposure are presented, and policies that support a smoke-free environment are outlined.
Organosoluble Silicon and Germanium Nanoclusters
Authors: Watanabe Akira , Miyashita Tokuji
Published: October 2009

The organosilicon nanoclusters (OSI) and organogermanium nanocluster (OGE) which have a few nanometer sized silicon or germanium cluster and organic groups bonded to the nanocluster surfaces show solubility in common organic solvents and good film processability by solution coating method. Using the coating films as precursors, inorganic silicon and germanium films were prepared by heat treatment in vacuo and laser annealing. The structural changes of the Si and Ge skeletons of the OSI and OGE by heat treatment and laser annealing were investigated by Raman spectroscopy. The laser-annealed films showed Raman bands assigned to the polycrystalline structure. The micropatterning of polycrystalline Ge by laser direct writing method was demonstrated. The organosoluble OGE is expected to be applicable as a germanium ink which gives polycrystalline Ge film.
Loma Linda Guide: A Stereolithographically Designed Surgical Template: Technique Paper
Authors: Kleinman Alejandro , Leyva Francisco , Lozada Jaime , Patel Rishi D.
Published: October 2009

A new flapless technique based on a template fabricated from a stereolithographic maxillary model is presented in this article. The proposed concept can be used to accurately control the tridimensional position of the dental implant. The laboratory procedures involving the fabrication of the surgical template are described.
Management of Combined Ridge Defect and Osteotome Sinus Floor Elevation With Simultaneous Implant Placement—A 36-Month Follow-Up Case Report
Authors: AlGhamdi Ali Saad Thafeed
Published: October 2009

This report demonstrated the management of combined ridge defect and maxillary sinus pneumatization with simultaneous implant placement. One case with vertical and horizontal ridge deficiency and sinus pneumatization in the maxillary premolar area was indicated for ridge augmentation and sinus elevation before implant placement. Implant osteotomy was enlarged using a ridge expansion osteotome to 1 mm short of the sinus floor; sinus elevation was performed using sinus lift osteotomes; the implant was placed; bone graft and resorbable membrane were used to augment the remaining defect. The second stage was done after 6 months, followed by final restoration. The patient was reevaluated for 36 months following the final prosthesis. The surgical site healed without complication following implant placement. During the second stage, the implant was completely surrounded by bone, with bone covering the buccal aspect of the cover screw. The X-ray showed a 5 mm apical shift of the sinus floor at 6 months post surgery. At 12 months post loading, crestal bone loss to the level of the first thread was noted; no changes were observed at the sinus or surrounding teeth. Pocket depth ranged from 3–4 mm. No further bone loss or soft tissue contour change was noted at 18, 24, 30, and 36 months post loading. The combination of these three techniques with simultaneous implant placement as described in this report seems to be successful. Further research is needed to evaluate whether the combination of these techniques with simultaneous implant placement offers similar results when compared with the stage approach.
A Removable Snore Reduction Appliance for a Mandibular Edentulous Patient
Authors: Flanagan Dennis
Published: October 2009

A snore reduction appliance can be constructed for the atrophic mandibular edentulous patient. Two endosseous implants can be surgically placed that retain a complete mandibular denture and, in turn, an overlying bimaxillary removable snore reduction appliance. A dual laminate appliance is vacu-form fitted to the maxillary teeth and the mandibular denture and luted in a protrusive relation with cold cure acrylic. The appliance maintains the mandible in a protrusive position to open the upper airway to reduce snoring.
Platform Switching and Bone Platform Switching
Authors: Carinci Francesco , Brunelli Giorgio , Danza Matteo
Published: October 2009

Bone platform switching involves an inward bone ring in the coronal part of the implant that is in continuity with the alveolar bone crest. Bone platform switching is obtained by using a dental fixture with a reverse conical neck. A retrospective study was performed to evaluate the effectiveness of conventional vs reverse conical neck implants. In the period between May 2004 and November 2007, 86 patients (55 females and 31 males; median age, 53 years) were operated and 234 implants were inserted: 40 and 194 were conventional vs reverse conical neck implants, respectively. Kaplan-Meier algorithm and Cox regression were used to detect those variables associated with the clinical outcome. No differences in survival and success rates were detected between conventional vs reverse conical neck implants alone or in combination with any of the studied variables. Although bone platform switching leads to several advantages, no statistical difference in alveolar crest resorption is detected in comparison with reverse conical neck implants. We suppose that the proximity of the implant abutment junction to the alveolar crestal bone gives no protection against the microflora contained in the micrograph. Additional studies on larger series and a combination of platform switching and bone platform switching could lead to improved clinical outcomes.
Correlation for Prediction and Estimation of Capillary Pressure to Account for Wettability and Wettability Variations Within Reservoir—Part 2
Authors: Zahoor Muhammad Khurram , Derahman Mohd. Nawi , Yunan Mat Hussin
Published: October 2009

Wettability plays an influential role in fluid flow behavior within a reservoir. Despite of its importance, it is not usually given the required significance during simulation studies. Different types of wettability may exist or co-exist within a reservoir which may change with the passage of time, depending on the prevailing conditions within a reservoir and also on the fluids which are injected for the purpose of enhanced oil recovery. In order to account for the effect of such wettabiliy variations on fluid flow behavior, a set of correlations have been developed to estimate capillary pressure, when the data from the core at extremely water-wet conditions is known. In this paper the developed set of correlations are further modified, so that they can be used quite effectively, when the capillary pressure data for any wettability conditions is known.
Optimum Non Hydrocarbon Gas Injection Development Process and Ultimate Recovery Maximization
Authors: Abed Abdulla , Zekri Abdulrazzag Y.
Published: October 2009

A multi layered heterogeneous oil reservoir was selected for this study. The integrated reservoir characterization model and the pertinent transformed reservoir simulation history matched model were quality assured and quality checked.

The development scheme was identified and selected where the pattern and completion of the wells were defined to fit the heterogeneity of the reservoir characterization model. Lateral and maximum block contact holes were investigated.

The development processes studied were mainly hydrogen sulphide, carbon dioxide, nitrogen and rich hydrocarbon gas. The Water Alternating Gas/ Simultaneous Water Alternating Gas (WAG / SWAG) processes were also assured. In addition to the main gas and WAG/SWAG processes, many miscible and immiscible EOR processes were also investigated though the results are not presented but may be referred to.

Field development options based on the development and processes schemes as well as reservoir management and long-term business plans including phases of implementation were identified and assured. The development option that maximizes the ultimate recovery factor was evaluated and selected.

The main objective of this work was to define the development process that could give a maximum ultimate recovery factor of more than 70 %. This could increase the total technical reserves by 30 % over the reserves based on classical water flooding reserves. It may be said that the life of the field could be extended to be almost doubled. The best technically development process that gives a maximum ultimate recovery factor of more than 70 % was the H2S-WAG development process. The enriched-WAG development scheme can be designed to give an equivalent ultimate recovery factor by enriching the gas.

The N2-WAG development process gives a relatively poor recovery factor. This is the lowest of all the Non-hydrocarbon Gas Injection (NHGI-WAG) development processes investigated.
The Use of High Pressure MICP Data in Reservoir Characterization, Developing a New Model for Libyan Reservoirs
Authors: Aboujafar Sami Mo.
Published: October 2009

Mercury injection capillary pressure data have been widely used to charaterize reservoir rocks, evaluating sealing capacity for traps and to explain the locations of hydrocarbon accumulations and transition zones. This method can determine a broader pore size distribution more quickly and accurately than other methods. It can be used to characterize pores ranging from 0.003 pm to 360 μm using a single theoretical model. The data produced (mercury intrusion volume at various pressures) can be used to calculate numerous sample characteristics such as pore size distributions, total pore volume, total pore surface area, median pore diameter, and sample densities (bulk and skeletal).

In this study the application of the high pressure mercury porosimetry technique in determination of different reservoir parameters have been investigated and a comparison between clastic and non clastic reservoirs was made. This was done by using data obtained from forty core samples from sandstone and carbonate reservoirs in North Africa. The results of different measurements and techniques were processed and interpreted. Theses included calculating the capillary pressure curves for the two rock types, converting the air/mercury curves to subsurface conditions and making sensitivity analysis for different parameters such as interfacial tension and contact angle. The distribution of pore-throat sizes and thus understanding the structures of pore systems in the reservoir has also been investigated. Another petrophysical reservoir property which was examined by this method was the existence of different types of porosity, (micro, meso and macro), which can be derived from the pore size distributions and compared between the two rock types, and therefore an attempt was made to classify the different rock types present in the studied samples.

A set of Empirical relationships which relate absolute permeability to the pore throat size distribution, pore throats at different mercury saturations, were derived for each rock type, and then these relationships were more investigated by introducing the effect of porosity. Finally, an estimation of the pore size from routine core data was made and compared with the measured data. These empirical relationships were also compared with other available relatioships obtained by other authors such as Pittman and Winland.
Multi Component Mass Transfer in Multiple Contact Miscibility Test; Forward and Backward Method
Authors: Wan Nurul Adyani Wan Razak , Wan Daud Wan Ata , Faisal Ahmad Hisyam , Zakaria Nur Atiqah
Published: October 2009

Multiple contact miscibility test for both forward and backward technique was conducted on light live reservoir crude with the API value of 41.5°. The experiment was conducted in four stages. At each stage of the experiment, a small amount of liquid and gas were sampled out from the PVT cell for compositional analysis.The multiple contact miscibility test simulate the continuous multiple contact process when the injection gas Carbon Dioxide (CO2) is injected into the reservoir fluid. In this study, the injection gas was mixed with the crude oil to achieve equilibrium at reservoir pressure and temperature. Dynamic miscibility between oil and Carbon Dioxide, which was not miscible on first contact was achieved by in-situ mass transfer of components between phases. This mass transfer phenomena, however, is not the same for forward and backward method of multiple contact miscibility test. At each stages of the test, different component has been transferred between phases with different amount and rate.

The results indicate that the amount of methane in vapour phase had increased significantly, as the number of contacts increases for both forward and backward multiple contact tests. The intermediate fraction became lighter and lighter as the contact progress. While the heavier component that was left out in the liquid phase susceptible to flocculate and produce heavy deposit such as asphaltenes. The phase envelope for liquid phase was generated using PVTi software with compositional data as an input. The change in the phase envelope shape explained the process that happened at each stages of the experiment. Ternary diagram was build to explain the difference in extraction process between forward and backward multiple contact test.

In conclusion, for CO2, some period of immiscible displacement must occur before mass transfer between reservoir oil and the advancing gas front establishes dynamic miscibility. This phenomenon was observed for both backward and forwards multiple contact experiment.
Reservoir Rock Types Application - Kashagan
Authors: Francesconi A. , Bigoni F. , Balossino P. , Bona N. , Marchini F. , Cozzi M.
Published: October 2009

Kashagan is a world-class supergiant oil field located in Kazakhstan, in the offshore of Caspian Sea. The reservoir is an isolated carbonate platform, Devonian to Carboniferous in age.

Definition of petrophysically significant Reservoir Rock Types (RRT) is critical in the reservoir characterisation and the dual petrophysical-geological significance of these RRTs is fundamental in providing a link to geological model drivers.

Kashagan carbonate field core studies highlight no relationship between lithofacies and petrophysical characteristics because of the strong diagenetic overprint. A RRT classification has been therefore performed integrating petrophysical data, Phi-K-MICP, with sedimentological, diagenetical and petrographical data. This process has allowed the definition of 7 RRTs that have been propagated into the Log domain using the kNN algorithm.

The resulting Log RRTs have been analysed in term of spatial distribution and petrophysical meaning. Their main geological driver is the 4th order cyclicity with a link to the Environment of Deposition, Karst intervals and Diagenetic Reservoir Quality Maps. The 3D modelling of RRTs should be therefore driven by VPC per 4°order cycles, obtained for each 3° order System Tract, consistently with both EoD and RQ Maps.

Core plugs and whole cores, "labelled" according to Log RRT propagation, have been analysed and characterised in terms of both K vs. Phi and Sw vs. Height relationships. Whole cores RRT show, systematically, higher K vs. Phi trends. This fact has been interpreted as a scale factor. Whole core K/Phi relationships have been therefore utilized for the synthetic permeability estimation. The KH-RRTs vs. KH-Well-Test comparison shows a good agreement in Platform Interior where wells are mainly producing from matrix, while in the Rim a large gap, due to Fractures and Megakarst, has been recognized.
Structural Uncertainty Modelling and Updating by Production Data Integration
Authors: Seiler A. , Rivenæs J. C. , Aanonsen S. I. , Evensen G.
Published: October 2009

An integrated reservoir characterization workflow, for structural uncertainty assessment and continuous updating of the structural reservoir model, by assimilation of production data, is presented. An ensemble of reservoir models, expressing explicitly the uncertainty resulting from seismic interpretation and time-to-depth conversion, is created. The top and bottom reservoir-horizon uncertainties are considered as a parameter for assisted history matching and are updated by sequential assimilation of production data using the Ensemble Kalman Filter (EnKF). To avoid modifications in the grid architecture and thus ensure a fixed dimension of the state vector, an elastic grid approach is proposed. The geometry of a base-case simulation grid is deformed to match the reservoir top and bottom horizon realizations. The method is applied to a synthetic example. The result is an ensemble of history-matched structural models with reduced and quantified uncertainty. The updated ensemble of structures provides a more reliable characterization of the reservoir architecture and a better estimate of the field oil in place.
Modeling CO2 Injection in a Fractured Chalk Experiment
Authors: Alavian S. A. , Whitson C. H.
Published: October 2009

This paper presents a modeling study of CO2 injection in a chalk core based on experimental data reported by Karimaie (2007). The experiment consisted of a vertically-oriented 19.6 cm long chalk outcrop core initially saturated with reservoir synthetic oil consisting of C1 and n-C7 at a temperature of 85°C and pressure of 220 bar. After saturating the core with the oil mixture by displacement a small "fracture" volume surrounding the core was created by heating the solid Wood's metal which originally filled the volume between the core and core holder.

Gas injection was first conducted using an equilibrium C1-n-C7 gas at 220 bar, resulting in no recovery by (thermodynamic) mass transfer but only from immiscible displacement with Darcy flow driven by induced pressure gradients and a minor impact of gravity-capillary equilibrium. Once oil production ceased in this first displacement, a second period with pure CO2 gas injection followed.

Our modeling was conducted with a compositional reservoir simulator. The 2-dimensional r-z model used fine grids for the core matrix and surrounding fracture. Automated history matching is used to match experimental data. The match to reported production data gave a high degree of confidence in the model. Oil recovery improved significantly by CO2 injection.

Our model study indicates that the recovery mechanism in the Karimaie experiment was dominated by Darcy displacement because of a low conductivity in the surrounding fracture. Another observation made in our study was the strong influence of surface separator temperature on surface oil production. Finally, gas injection rate changes had a significant impact on recovery performance for CO2 injection. Gravity-capillary recovery mechanism was of minor importance in the Karimaie experiments.
Application of the Infrasoinic Passive Differential Spectroscopy (IPDS) for Hydrocarbon Direct Detection and Reservoir Monitoring in Fields of the North-Caspian Basin: Achievements and Challenges
Authors: Makhous Monzer , Rode Paul Ernest , Kaya Serdar
Published: October 2009

This technique is based on the principles that hydrocarbon reservoirs as a multi-fluids system in porous medium has an unconventional (non linear) transfer characteristics for acoustic waves. Hydrocarbon fluid in porous system can be detected as a characteristic deformation of the natural earth noise spectra in the acoustic low frequency range between 0.2 and 10 Hz. The anomalous absorption/emission of micro-seismic noise is used as source for direct detection of oil/gas accumulation (OGA) trapped in a porous matrix/reservoir.

In these conditions, the OGA passes in generation of its proper infra-acoustic waves. The mechanical energy of hydrodynamic nature is simply transforming in acoustic energy generating the IPDS waves/signals (downward conversion). The spectral amplitude of background micro-seismic emission above the OGA exceeds considerably that of outside the OGA in the frequency range of 0.1-30 Hz. Measuring and processing the characteristic spectral amplitude of this generated and amplified natural micro-seismic noise defines the presence or absence of OGA.

Applying this technology to three important fields in the North Caspian basin has shown that it provides a detailed spatial hydrocarbon distribution, reservoir delineation and monitoring and reliable estimation of hydrocarbon potential reserves or resting un-produced oils. Correlation of field production data with the passive seismic monitoring results shows an enough satisfactory output of the applied technology for reservoir monitoring. This technology could be also promising for EOR/IOR projects, as well as for horizontal and vertical well drilling projects.

However, in faulted disintegrated zones owing to increased heterogeneous stress as factor of both micro- and macro-seismic instability the IPDS signals are somewhat deformed. This fact implies some ambiguities, which have to be clarified and resolved.
Experimental K-value Prediction
Authors: Rahman Saifur
Published: October 2009

The Equilibrium ratios (K-values) depend on temperature, pressure and the overall composition of the reservoir fluid. Several correlations are being used and are considered accurate enough. But on close examining these correlations provide accurate results only at lower pressures. This is because at lower pressure the K-values are primarily dependent on pressure and temperature. The compositional dependence which is more complicated to model happens at higher pressures. The compositional dependence is believed to be only a function of convergence pressure. When we consider that predicting convergence pressure in itself is dependent on the correlations, we can fathom the cause of inaccurate prediction of K-values. We believe that there is not enough data available to generate accurate correlations. The inaccuracy of correlations in prediction of the K-values will be shown in this paper by comparison with the experimental data.

Introduction

Phase behavior data is one of the most important tools used to evolve reservoir development strategy. Knowledge of Vapor-Liquid-Equilibrium (VLE) data is essential for understanding the separation processes in the reservoir as well as in the surface equipment. This information helps in selection of equipment for flash separation at the well head, distillation columns and even for design of pipeline and unit operations. The thermodynamic equilibrium between vapor and liquid phases depend on equality of temperature, pressure, and fugacity of each component in both phases.
Akaike's Information Criterion in Packer Test Analysis
Authors: Rafiee M. M. , Haefner F. , Voigt H. D.
Published: October 2009

Gradient techniques are used predominantly in History Matching and Optimization. In this paper gradient technique was used in estimation of multiple packer test data (permeability distribution of very low permeable formations). A high pressure gas chamber has been released into the formation and pressure changes in this chamber and two nearby observation chambers have been measured.

A simulation model has been set up for this experiment and Eclipse black-oil simulator was used for simulation. By defining region multipliers close to packer tools and validating the model, the Gradient Optimization technique of SIMOPT-History Matching software has been used to find permeability multiplier in these regions.

Akaike's information criterion (AIC) concept which is the tradeoff between minimum of objective function and the necessary complexity of the reservoir description could be used plausibly to assess the uniqueness of the selected model. Although the Objective Function is reduced with increasing the number of parameters, AIC could estimate the most reliable unique solution avoiding an over-parameterization.

The proposed technique offers a way to estimate reservoir parameters at In-Situ reservoir conditions, accounting for heterogeneities and could prove reasonably the uniqueness of the selected model among different sets of identified solutions.
Rock Typing: An Integrated Reservoir Characterization Tool to Construct a Robust Geological Model in Abu Dhabi Carbonate Oil Field
Authors: Salman Salman M. , Bellah Sameer
Published: October 2009

Rock typing is an essential step in carbonate reservoir characterization and geological model building for reservoir simulation. A static rock type is defined as "a rock unit characterized by similar depositional and digenetic processes resulting in a typical and unique Ø-K relationship and capillary pressure curve at given wettability. Reservoir representative rock types lead to a better understanding of reservoir fluid movement and oil recovery.

This paper establishes a deterministic rock type scheme in a carbonate reservoir and presents a methodology to distribute these rock types vertically and laterally in the 3D geological model using wells data, conceptual model and reservoir structure map obtained from 3D seismic.
Co-optimization of CO2 EOR and Sequestration Process in a North Sea Chalk Reservoir
Authors: Forooghi A. , Hamouda A. A , Eilertsen T.
Published: October 2009

Traditional EOR approaches intend to minimize the injected CO2 to reduce the high cost of the purchased gas, while this approach does not satisfy the sequestration objective to maximize the CO2 stored in the reservoir by the end of the flooding period. In this paper, a new approach is presented where, a methodology is developed to optimize both EOR and sequestration processes.

CO2 injection into a North Sea chalk field is studied using a compositional reservoir simulator. We have investigated the effect of six parameters including injection scheme, injector and producer well type, well control mode, slug size and the WAG ratio on the coupled CO2 EOR and sequestration process. Three different injection strategies using either pure CO2 or a mixture of CO2 and hydrocarbon gas including WAG, continuous CO2 injection and soak alternating CO2 injection have been investigated.

Three well configurations are considered. It includes a vertical and two horizontal well options completed in the third and fifth layer of the reservoir. We have considered BHP and rate control as effective well control modes.

Experimental design is used to perform an efficient sensitivity analysis on the mentioned parameters. Two objective functions have been defined, aimed at co-optimization of EOR and sequestration processes while respecting the economy of the process through minimizing recycled CO2.

In this work a methodology / approach has been developed, which could be applied to other fields. In the case studied here, the results show that the water alternating gas injection scheme using a mixture of CO2 and hydrocarbon gas to be the optimum case (EOR and sequestration process).
Evaluating the Impact of Geophysical Uncertainties on Gross Rock Volume in a Low Relief Carbonate Field, offshore Abu Dhabi
Authors: Gazet S. , Chavanne E. , Khalaf A.
Published: October 2009

Quantifying the geophysical uncertainties is an important part of field evaluation because it has a direct impact on the extension of the oil pool and on the volumes in place. In low relief structures the uncertainty on Gross Rock Volume can be a major issue because small changes in the top reservoir depth map may drastically impact the closure area.

Our field, offshore Abu Dhabi, is an example where this uncertainty issue on gross rock volume is important. The reservoir levels are located in the Lower Cretaceous Formation. A high standard OBC survey recently acquired drastically improved the vision of the field compared to previous sparse 2D lines of various vintages. This new 3D dataset also emphasized the importance of overburden events effects on the top reservoir time map. Signal phase instability appears to be affecting the dataset and hence the top reservoir time map.

This paper presents the methodology followed to optimize the Gross Rock Volume estimation. Statistics as well as analytical methods are combined to assess carefully the uncertainties. The top reservoir time map is quality controlled with respect to key processing steps, overburden artifacts effects and picking uncertainty. The uncertainty related to time to depth conversion is assessed by scenarios around a selected base case. Multiple top reservoir map realizations are then computed, integrating all uncertainties. The objective of the study is to generate P10, P50 and P90 depth maps for the Top reservoir that fully integrate the whole range of geophysical uncertainties. These maps will then be implemented in the geological and reservoir models for further calculations to get P10, P50 and P90 reserves evaluation.
Discrete Element Erosion Modelling—A Grain-Scale Approach
Authors: Marrion M. C. , Woods A. W.
Published: October 2009

We report a conceptually simple and robust particle-scale model of hydrodynamic erosion. The model treats each particle of the granular matrix as a discrete element, and computes the erosive and cohesive forces acting upon it due to the oil flow and the surrounding particles. A stochastic erosion criterion is then used to determine if the particle is eroded, depending on the nett force acting upon it and the geometrical constraints imposed on it by the neighbouring particles. The erosion is allowed to progress particle-by-particle, and the pressure field is successively recalculated to take account of the modified particle matrix. The model predicts the formation of wormhole-like voids, which grow upstream into the particle matrix, and develop into a dendritic network. Wormhole growth does not begin until the ratio of erosive to cohesive force exceeds a critical value; as this ratio increases, the amount of erosion increases. The model also shows that non-uniform distributions of permeability, such as those due to localized geological features like intrusions, can significantly modify the characteristics of the erosion and reduce the total amount erosion. These findings are in agreement with previous experimental observations.
Poverty reduction and water governance: lessons from and problems in Northwestern China
Authors: Hu Desheng
Published: October 2009

Great achievements have been made in poverty reduction in Northwestern China, an area which contains a higher than average proportion of 55 different ethnic minority groups, with over half of the villagers being self-supporting, and where the main factors leading to poverty are adverse natural conditions, shortage of available water, weak infrastructure and backward social development. By analyzing the institutional framework relating to the water sector and the meeting of different water requirements (i.e., the human right to water, the environmental right to water, and economic development), as well as presenting case studies on two model villages and two kinds of important water infrastructures (i.e., the water split and silt dam), the role of good water governance in China's development-oriented poverty reduction process is identified, with particular focus on lessons that can be learned. In conclusion, lessons are drawn from the aspects of policy and management, balancing different and competitive water requirements as well as short-term and long-term benefits of the poor, and stakeholder participation.